Rare earth and trace elements of fossil vertebrate bioapatite as palaeoenvironmental and sedimentological proxies

NASA Astrophysics Data System (ADS)

Žigaitė, Živilė; Fadel, Alexandre; Pérez-Huerta, Alberto; Jeffries, Teresa

2015-04-01

Rare earth (REE) and trace element compositions of fossil vertebrate dental microremains have been studied in Silurian and Devonian vertebrate dental scales and spines in-situ, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Samples were selected from the well-known Silurian bone beds of Vesiku and Ohesaare in Saaremaa island of Estonia, and a number of Lower Devonian localities from Spitsbergen (Svalbard), Andrée Land group. Biomineral preservation was assessed using spot semi-quantitative elemental chemistry (SEM-EDS) and electron back-scatter difractometry (EBSD) for cristallinity imaging. The obtained PAAS shale-normalised REE concentrations were evaluated using basic geochemical calculations and quantifications. The REE patterns from the Lower Devonian vertebrate apatite from Andrée Land, Spitsbergen (Wood Bay and Grey Hœk formations) did not show any recognisable taxon-specific behavior, but had rather well expressed differences of REE compositions related to biomineral structure and sedimentary settings, suggesting REE instead to reflect burial environments and sedimentological history. The Eu anomaly recorded in two of the studied localities but not in the other indicate different taphonomic conditions and palaeoenvironment, while La/Sm, La/Yb ratios sugeest considerable influence of terrestrial freshwater during the early diagenesis. The La/Yb and La/Sm plots also agree with the average REE concentrations, reflecting domination of the adsoption over substitution as principal REE uptake mechanism in the fossils which had significantly lower overall REE concentrations, and vice versa. Vesiku (Homerian, Wenlock) microremains yielded very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with strong enrichment in middle REE and depletion in heavy REE. Negative Europium (Eu) anomaly was pronounced in all the profiles, but Cerium (Ce) anomalies were not detected suggesting possible suboxic to anoxic conditions of the bottom and pore waters during the formation of Vesiku bone bed. In Ohesaare (Pridoli), the REE compositions were nearly identical across all the morphotypes and histologies of acanthodian microremains showing flat REE patterns with slight depletion in HREE. There were no visible enrichment in MREE, indicating relatively good preservation of original bioapatite and likely absence of any pronounced fractionated REE incorporation during later stages of diagenesis. The shale normalised (La/Yb)SN and (La/Sm)SN REE ratio compilations showed addsorption as dominating REE uptake mechanism across all the studied microfossils. The absence of well-defined Ce anomaly suggest oxic palaeoseawater conditions, which agrees with existing interpretations of Ohesaare sequence as high-energy shoal and regressive open ocean sedimentary environment.

Rare earth elements (REE) as natural and applied tracers in the catchment area of Gessental valley, former uranium mining area of Eastern Thuringia, Germany

NASA Astrophysics Data System (ADS)

Buechel, G.; Merten, D.; Geletneky, J. W.; Kothe, E.

2003-04-01

Between 1947 and 1990 about 113.000 t of uranium were excavated at the former uranium mining site of Ronneburg (Eastern Thuringia, Germany). The legacy consists of more than 200 million m^3 of metasedimentary rocks rich in organic matter, sulfides and heavy metals originally deposited in mining heaps at the surface. The metasedimentary rocks formed under anoxic conditions about a 400 Mio. years ago are now exposed to oxic conditions. The oxidation of markasite and pyrite results in the formation of H_2SO_4. The formation of acid mine drainage (AMD) leads to high concentrations of uranium, rare earth elements (REE) and other heavy metals in surface water, seepage water and groundwater. This mobilization is due to alteration enhanced by high microbial activity and low pH. The tolerance mechanisms towards heavy metal pollution of soil substrate and surface/groundwater has allowed the selection of microbes which have, e.g. specific transporter genes and which are associated to plants in symbiotic interactions like mycorrhiza. In order to follow the processes linking alteration of metasedimentary rocks to biological systems the use of tracers is needed. One group of such tracers occuring in high concentrations in the water phase at the Ronneburg mining site are the REE (La-Lu) which are featured by very similar chemical behaviour. They show smooth but continuous variations of their chemical behaviour as a function of atomic number. For seepage water of the waste rock dump Nordhalde - sampled over a period of two years - the shale normalized REE patterns show enrichment of heavy REE and only minor variations, although the concentration differs. At sampling points in the surface water and in groundwater rather similar REE patterns were observed. Thus, REE can be used as tracers to identify diffuse inflow of REE-rich acid mine drainage of the dumps into the creek and the sediments. The absolute concentrations of REE in the creek and in ground water are up to 1000 times less than in seepage water due to mixing and (co)precipitation of REE. Lu/La and Sm/La relations show a significant decrease with increasing distance from the dump caused by preferential (co)precipitation of heavy REE with amorphous Fe-hydroxides along the Gessenbach. Thus, REE patterns can not only be used as tracers but also to study processes. In contrast to the patterns of the seepage, the REE patterns of the Silurian rocks as determined by LA-ICP-MS feature rather flat patterns with enrichment of middle REE (Sm - Dy). Results from batch experiments show preferentially leaching of heavy REE for all investigated source rocks. The highest absolute concentrations of REE appear in the eluates of the Silurian 'Ockerkalk'. Since the REE pattern closely reflects the pattern found in the seepage water it is assumed to be the most important source for the occurence of the REE pattern observed in seepage water. Studies of microbial heavy metal retention were performed by direct incubation of seepage water using well characterized fungal and bacterial strains. Using the bacterium Escherichia coli for incubation of seepage water sorption of heavy metals to biomass was observed. Use of the fungus Schizophyllum commune for incubation, however, has a much more pronounced effect including significant fractionation of REE pointing to the possibility of a specific active uptake mechanism. Bioextraction with bacteria and fungal mycelia might be an alternative to plant growth and phytoextraction and might be preferable for AMD water treatment since no soil substrate is necessary. Future research must be directed towards genes for active transport, intra- or extracellular storage proteins and their application. Biotechnological use of such genes in, e.g., strains of E. coli, might yield highly useful bioremediation strains that can help to reduce the ecological effects of pollution resulting from former mining activities.

Chemistry of the Apollo 11 highland component

NASA Technical Reports Server (NTRS)

Laul, J. C.; Papike, J. J.; Simon, S. B.; Shearer, C. K.

1983-01-01

Thirty-eight Apollo 11 lunar highland fragments from coarse fines 10085 have been subjected to petrologic and chemical study. Six major chemical groups are identified: (a) high-K KREEP; (b) anorthosite with a 10X chondrite positive Eu anomaly and anorthosite with 30X positive Eu anomaly; (c) ANT; (d) LKFM; (e) anorthositic gabbro with no Eu anomaly, with a positive Eu anomaly, and with a negative Eu anomaly; and (f) dominant Highland component, 2X-10X chondrite with a positive 10X-14X Eu anomaly. Newly recognized groups are presented based on the REE patterns: (a) ANT group with 5X La and a 22X positive Eu anomaly; (b) 10X flat with 14X positive Eu anomaly; and (c) 2-3X flat with a 10X positive Eu anomaly. The highland suite is very low in K and REE, and is overall quite similar to the Apollo 16 suite.

Rare earth elements in street dust and associated health risk in a municipal industrial base of central China.

PubMed

Sun, Guangyi; Li, Zhonggen; Liu, Ting; Chen, Ji; Wu, Tingting; Feng, Xinbin

2017-12-01

The content levels, distribution characteristics, and health risks associated with 15 rare earth elements (REEs) in urban street dust from an industrial city, Zhuzhou, in central China were investigated. The total REE content (∑REE) ranged from 66.1 to 237.4 mg kg -1 , with an average of 115.9 mg kg -1 , which is lower than that of Chinese background soil and Yangtze river sediment. Average content of the individual REE in street dust decreased in the order Ce > La > Nd > Y > Pr > Sm > Gd > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The chondrite-normalized REE pattern indicated light REE (LREE) enrichment, a relatively steep LREE trend, heavy REE (HREE) depletion, a flat HREE trend, a Eu-negative anomaly and a Ce-positive anomaly. Foremost heavy local soil and to less degree anthropogenic pollution are the main sources of REE present in street dust. Health risk associated with the exposure of REE in street dust was assessed based on the carcinogenic and non-carcinogenic effect and lifetime average daily dose. The obtained cancer and non-cancer risk values prompt for no augmented health hazard. However, children had greater health risks than that of adults.

REE partitioning between apatite and melt in a peralkaline volcanic suite, Kenya Rift Valley

USGS Publications Warehouse

Macdonald, R.; Baginski, B.; Belkin, H.E.; Dzierzanowski, P.; Jezak, L.

2009-01-01

Electron microprobe analyses are presented for fluorapatite phenocrysts from a benmoreite-peralkaline rhyolite volcanic suite from the Kenya Rift Valley. The rocks have previously been well characterized petrographically and their crystallization conditions are reasonably well known. The REE contents in the M site increase towards the rhyolites, with a maximum britholite component of ~35 mol.%. Chondrite-normalized REE patterns are rather flat between La and Sm and then decrease towards Yb. Sodium and Fe occupy up to 1% and 4%, respectively, of the M site. The major coupled substitution is REE3+ + Si4+ ??? Ca2+ + P5+. The substitution REE3+ + Na+ ??? 2Ca2+ has been of minor importance. The relatively large Fe contents were perhaps facilitated by the low fo2 conditions of crystallization. Zoning is ubiquitous and resulted from both fractional crystallization and magma mixing. Apatites in some rhyolites are relatively Y-depleted, perhaps reflecting crystallization from melts which had precipitated zircon. Mineral/glass (melt) ratios for two rhyolites are unusually high, with maxima at Sm (762, 1123). ?? 2008 The Mineralogical Society.

U, Th, Pb and REE abundances and Pb 207/Pb 206 ages of individual minerals in returned lunar material by ion microprobe mass analysis.

NASA Technical Reports Server (NTRS)

Andersen, C. A.; Hinthorne, J. R.

1972-01-01

Results of ion microprobe analyses of Apollo 11, 12 and 14 material, showing that U, Th, Pb and REE are concentrated in accessory minerals such as apatite, whitlockite, zircon, baddeleyite, zirkelite, and tranquillityite. Th/U ratios are found to vary by over a factor of 40 in these minerals. K, Ba, Rb and Sr have been localized in a K rich, U and Th poor glass phase that is commonly associated with the U and Th bearing accessory minerals. Li is observed to be fairly evenly distributed between the various accessory phases. The phosphates have been found to have REE abundance patterns (normalized to the chondrite abundances) that are fairly flat, while the Zr bearing minerals have patterns that rise steeply, by factors of ten or more, from La to Gd. All the accessory minerals have large negative Eu anomalies. Radiometric age dates (Pb 207/Pb 206) of the individual U and Th bearing minerals compare favorably with the Pb 207/Pb 206 age of the bulk rocks.

Possible impact-induced refractory-lithophile fractionations in EL chondrites

NASA Astrophysics Data System (ADS)

Rubin, Alan E.; Huber, Heinz; Wasson, John T.

2009-03-01

Literature data show that refractory-lithophile elements in most chondrite groups are unfractionated relative to CI chondrites; the principal exception is the EL-chondrite group whose observed falls (all of which are type 6) are depleted in Ca and light REE. In contrast, literature data and our new INAA data on EL3 PCA 91020, EL3 MAC 88136 and EL4 Grein 002 show that some replicates of these samples have nearly flat REE patterns (unlike those of EL6 chondrites); other replicates exhibit fractionated REE patterns similar to those of EL6 chondrites. Petrographic examination shows that many EL6 (and some EL3 and EL4) chondrites are impact-melt breccias or contain impact-melted portions. We suggest that the same impact processes that formed these breccias and produced melt are responsible for the observed bulk compositional fractionations in refractory-lithophile elements, i.e., EL6 chondrites were produced from initially unequilibrated EL3 material. When large amounts of impact heat were deposited, plagioclase and/or oldhamite (CaS) (the major REE carriers in enstatite chondrites) may have been melted and then transported appreciable (>10 cm) distances. EL6 chondrites represent the residuum that is depleted in REE (particularly in LREE) and Ca. Unlike the case for EL chondrites, our new INAA data on ALH 84170, EET 87746 and SAH 97096 (all EH3) show some scatter but are consistent with the EH group having uniform refractory-lithophile abundances.

Transfer of rare earth elements from natural metalliferous (copper and cobalt rich) soils into plant shoot biomass of metallophytes from Katanga (Democratic Republic of Congo)

NASA Astrophysics Data System (ADS)

Pourret, Olivier; Lange, Bastien; Jitaru, Petru; Mahy, Grégory; Faucon, Michel-Pierre

2014-05-01

The geochemical behavior of rare earth elements (REE) is generally assessed for the characterization of the geological systems where these elements represent the best proxies of processes involving the occurrence of an interface between different media. REE behavior is investigated according to their concentrations normalized with respect to the upper continental crust. In this study, the geochemical fingerprint of REE in plant shoot biomass of an unique metallicolous flora (i.e., Crepidorhopalon tenuis and Anisopappus chinensis) was investigated. The plants originate from extremely copper and cobalt rich soils, deriving from Cu and Co outcrops in Katanga, Democratic Republic of Congo. Some of the species investigated in this study are able to accumulate high amounts of Cu and Co in shoot hence being considered as Cu and Co hyperaccumulators. Therefore, assessing the behavior of REE may lead to a better understanding of the mechanisms of metal accumulation by this flora. The data obtained in this study indicate that REE uptake by plants is not primarily controlled by their concentration and speciation in the soil as previously shown in the literature (Brioschi et al. 2013). Indeed, the REE patterns in shoots are relatively flat whereas soils patterns are Middle REE enriched. In addition, it is worth noting that Eu enrichments occur in aerial parts of the plants. These positive Eu anomalies suggest that Eu3 + can form stable organic complexes replacing Ca2 + in several biological processes as in xylem fluids associated with the general nutrient flux. Therefore, is is possible that the Eu mobility in these fluids is enhanced by its reductive speciation as Eu2 +. Eventually, the geochemical behavior of REE illustrates that metals accumulation in aerial parts of C. tenuis and A. chinensis is mainly driven by dissolved complexation. Brioschi, L., Steinmann, M., Lucot, E., Pierret, M., Stille, P., Prunier, J., Badot, P., 2013. Transfer of rare earth elements (REE) from natural soil to plant systems: implications for the environmental availability of anthropogenic REE. Plant and Soil, 366, 143-163.

Rare earth element fingerprints in Korean coastal bay sediments: Association with provenance discrimination

NASA Astrophysics Data System (ADS)

Kang, Jeongwon; Woo, Han Jun; Jang, Seok; Jeong, Kap-Sik; Jung, Hoi-Soo; Hwang, Ha Gi; Lee, Jun-Ho; Cho, Jin Hyung

2016-09-01

Rare earth elements (REEs: La-Lu) in surface sediments collected from the mouth and middle tidal flats of Gomso Bay, South Korea, in August 2011 and May 2012 were analyzed to investigate the fine-grained sediment provenance. The upper continental crust (UCC)-normalized light REEs (LREEs: La to Nd) were more enriched than the middle REEs (MREEs: Sm to Dy) and heavy REEs (HREEs: Ho to Lu), resulting in large (La/Yb)UCC (1.9 ± 0.4) to (Gd/Yb)UCC (1.4 ± 0.2) ratios. The monthly (La/Yb)UCC values differed between the mouth and middle tidal flats due to deposition of fine-grained sediments that originated from distant rivers (the Geum and Yeongsan) and the Jujin Stream, located on the southern shore of the inner bay. We observed relative reductions in the (La/Yb)UCC value and REE content in the sediments from the mouth of the bay compared with those from Jujin Stream sediments. Confined to the middle tidal flat around the KH Line of Jujin Stream, the sediments, most enriched in LREEs but depleted in Eu, were distributed in August as strong Jujin Stream runs. Here, we suggest that an increase in LREE/HREE and decrease in MREE/LREE ratios can be used as a proxy to identify the Jujin Stream provenance in mixed riverine sediments and to trace Jujin Stream sediments within the Gomso Bay tidal flat, especially in the summer rainy season.

Multistage metasomatism in lithospheric mantle beneath V. Grib pipe (Arkhangelsk diamondiferous province, Russia): evidence from REE patterns in garnet xenocrysts.

NASA Astrophysics Data System (ADS)

Shchukina, Elena; Alexei, Agashev; Nikolai, Pokhilenko

2015-04-01

150 garnet xenocrysts from V. Grib kimberlite pipe were analyzed for major and trace elements compositions. 70 % of garnet belong to lherzolite field; 14 % - megacrysts and pyroxenites; 11 % - eclogites; 4 % - harzburgite; 1 % (1- wehrlite defined by Sobolev (1973). Harzburgite garnets: sinusoidal REE patterns Smn/Ern > 5 (5.2 - 19.8). low Y (0.5 - 3.9 ppm), Zr (1.1 - 44.6 ppm), Ti (54 - 1322 ppm). Wehrlite garnetd: close to sinusoidal REE patterns, Smn/Ern - 1.8. Megacrysts and pyroxenites garnets: normal REE patterns Smn/Ern < 1 (0.2 - 0.6), high TiO2 (0.9 - 1.3 wt %). Lherzolite garnets 70 % show four groups of REE patterns similar to peridotite xenoliths (Shchukina et al., 2013, 2015). 1-st contains MREE at С1 level, Sm/Ern - 0.03, La/Ybn - 0.002. increasing La -Yb range, low Y, Zr, Ti indicating residual nature. 2-nd: MREE at 2 - 13 chondrite units, Smn/Ern (0.16 - 0.98), La/Ybn - 0.001 - 0.040 and flat pattern from MREE to HREE. 3-rd -MREE at 5 - 14 chondrite units, Sm/Ern > 1 (1.05 - 4.81) La/Ybn - 0.010-0.051 increasing an hump at MREE decreasing to HREE. 4-th: sinusoidal REE, Sm/Ern 4.2 - 27.2. and harzburgite Y, Zr, Ti . Average Cr2O3 content increases from 2-nd to the 3-rd group (3.3 to 5.7 wt%) and 4th (7.9 wt %). Average Y/Zr decreases from 2-nd (0.6) to 3rd (0.2) and 4th group (0.08). REE and Y, Zr, Ti indicate the metasomatic origin of garnets of 2, 3. 4 groups. Modeling of TREfor equilibrated melts and fractional crystallization 2nd group close to Turyino field basalts and 3-rd - to Izmozero field picrites of Arkhangelsk diamondiferous province (ADP). Basing on geochemical data of garnet xenocrysts and garnets and clinopyroxenes in peridotites (Shchukina et al., 2013, 2015) we suppose at least 3 stage of high-temperature metasomatic enrichment. 1st stage - is enrichment of residual garnets (found only in peridotite garnets) in LREE by the influence of carbonatite melt close to the Mela field carbonatites of ADP. REE patterns in clinopyroxenes from these peridotite samples and the geochemical modeling results show that clinopyroxenes are also in equilibrium with carbonatite melt. Formation of garnet with the sinusoidal REE pattern could also occurs during carbonatite stage of mantle metasomatism. The 2- nd stage - is formation of garnets of group 3 from the melt of composition close to Izhmozero field picrites. Garnets of group 3 are of lherzolite paragenesis on the content of CaO and Cr2O3, but their REE patterns are close to sinusoidal patterns. The final stage of mantle metasomatism is the formation of garnets of group 2 exposed to the melt of composition close to Turyino field basalts. Garnets of group 2 have low Cr2O3 that indicate the significant amounts of basaltic component in the resulting melt composition or direct crystallization from the melt in case of most low-chromium garnets and megacrysts garnets. Modeling results show that the formation of the garnets of group 2 in peridotites associated with crystallization of the clinopyroxenes. At this stage of mantle metasomatism garnets have typical major and trace element lherzolite composition.

Eclogites and garnet pyroxenites from Kimberley, Kaapvaal craton, South Africa: their diverse origins and complex metasomatic signatures

NASA Astrophysics Data System (ADS)

Shu, Qiao; Brey, Gerhard P.; Pearson, D. Graham

2018-06-01

We describe the petrography and mineral chemistry of sixteen eclogite and garnet pyroxenite xenoliths from the reworked Boshof road dump (Kimberley) and define three groups that stem from different depths. Group A, the shallowest derived, has low HREE (heavy rare earth element) abundances, flat middle to heavy REE patterns and high Mg# [= 100·Mg/(Mg + Fe)]. Their protoliths probably were higher pressure cumulates ( 0.7 GPa) of mainly clinopyroxene (cpx) and subordinate orthopyroxene (opx) and olivine (ol). Group B1 xenoliths, derived from the graphite/diamond boundary and below show similarities to present-day N-MORB that were modified by partial melting (higher Mg# and positively inclined MREE (middle REE) and HREE (heavy REE) patterns of calculated bulk rocks). Group B2 samples from greatest depth are unique amongst eclogites reported so far worldwide. The calculated bulk rocks have humped REE patterns with very low La and Lu and prominent maxima at Sm or Eu and anomalously high Na2O (up to 5 wt%) which makes protolith identification difficult. The complex trace element signatures of the full spectrum of Kimberley eclogites belie a multi-stage history of melt depletion and metasomatism with the introduction of new phases especially of phlogopite (phlog). Phlogopite appears to be characteristic for Kimberley eclogites and garnet peridotites. Modelling the metasomatic overprint indicates that groups A and B1 were overprinted by volatile- and potassium-rich melts probably by a process of chromatographic fractionation. Using constraints from other metasomatized Kimberley mantle rocks suggest that much of the metasomatic phlogopite in the eclogites formed during an intense episode of metasomatism that affected the mantle beneath this region 1.1 Gyr ago.

Geochemistry of loess-paleosol sediments of Kashmir Valley, India: Provenance and weathering

NASA Astrophysics Data System (ADS)

Ahmad, Ishtiaq; Chandra, Rakesh

2013-04-01

Middle to Late Pleistocene loess-paleosol sediments of Kashmir Valley, India, were analyzed for major, trace and REE elements in order to determine their chemical composition, provenance and intensity of palaeo-weathering of the source rocks. These sediments are generally enriched with Fe2O3, MgO, MnO, TiO2, Y, Ni, Cu, Zn, Th, U, Sc, V and Co while contents of SiO2, K2O, Na2O, P2O5, Sr, Nb and Hf are lower than the UCC. Chondrite normalized REE patterns are characterized by moderate enrichment of LREEs, relatively flat HREE pattern (GdCN/YbCN = 1.93-2.31) and lack of prominent negative Eu anomaly (Eu/Eu* = 0.73-1.01, average = 0.81). PAAS normalized REE are characterized by slightly higher LREE, depleted HREE and positive Eu anomaly. Various provenance discrimination diagrams reveal that the Kashmir Loess-Paleosol sediments are derived from the mixed source rocks suggesting large provenance with variable geological settings, which apparently have undergone weak to moderate recycling processes. Weathering indices such as CIA, CIW and PIA values (71.87, 83.83 and 80.57 respectively) and A-CN-K diagram imply weak to moderate weathering of the source material.

Metal loading levels influence on REE distribution on humic acid: Experimental and Modelling approach

NASA Astrophysics Data System (ADS)

Marsac, R.; Davranche, M.; Gruau, G.; Dia, A.

2009-04-01

In natural organic-rich waters, rare earth elements (REE) speciation is mainly controlled by organic colloids such as humic acid (HA). Different series of REE-HA complexation experiments performed at several metal loading (REE/C) displayed two pattern shapes (i) at high metal loading, a middle-REE (MREE) downward concavity, and (ii) at low metal loading, a regular increase from La to Lu (e.g. Sonke and Salters, 2006; Pourret et al., 2007). Both REE patterns might be related to REE binding with different surface sites on HA. To understand REE-HA binding, REE-HA complexation experiments at various metals loading were carried out using ultrafiltration combined with ICP-MS measurements, for the 14 REE simultaneously. The patterns of the apparent coefficients of REE partition between HA and the inorganic solution (log Kd) evolved regularly according to the metal loading. The REE patterns presented a MREE downward concavity at low loading and a regular increase from La to Lu at high loading. The dataset was modelled with Model VI by adjusting two specific parameters, log KMA, the apparent complexation constant of HA low affinity sites and DLK2, the parameter increasing high affinity sites binding strength. Experiments and modelling provided evidence that HA high affinity sites controlled the REE binding with HA at low metal loading. The REE-HA complex could be as multidentate complexes with carboxylic or phenolic sites or potentially with sites constituted of N, P or S as donor atoms. Moreover, these high affinity sites could be different for light and heavy REE, because heavy REE have higher affinity for these sites, in low density, and could saturate them. These new Model VI parameter sets allowed the prediction of the REE-HA pattern shape evolution on a large range of pH and metal loading. According to the metal loading, the evolution of the calculated REE patterns was similar to the various REE pattern observed in natural acidic organic-rich waters (pH<7 and DOC>10 mg L-1). As a consequence, the metal loading could be the key parameter controlling the REE pattern in organic-rich waters.

Rare earth patterns in shergottite phosphates and residues

NASA Technical Reports Server (NTRS)

Laul, J. C.

1987-01-01

Leaching experiments with 1M HCl on ALHA 77005 powder show that rare earth elements (REE) are concentrated in accessory phosphate phases (whitlockite, apatite) that govern the REE patterns of bulk shergottites. The REE patterns of whitlockite are typically light REE-depleted with a negative Eu anomaly and show a hump at the heavy REE side, while the REE pattern of apatite (in Shergotty) is light REE-enriched. Parent magmas are calculated from the modal compositions of residues of ALHA 77005, Shergotty, and EETA 79001. The parent magmas lack a Eu anomaly, indicating that plagioclase was a late-stage crystallizing phase and that it probably crystallized before the phosphates. The parent magmas of ALHA 77005 and Shergotty have similar REE patterns, with a subchondritic Nd/Sm ratio. However, the Sm/Nd isotopoics require a light REE-depleted source for ALHA 77005 (if the crystallization age is less than 600 Myr) and a light REE-enriched source for Shergotty. Distant Nd and Sr isotopic signatures may suggest different source regions for shergottites.

Geochemistry and structure of the Hawley Formation: Northwestern Massachusetts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, J.; Jacobi, R.

1993-03-01

The Hawley Formation in northwestern Massachusetts is composed of mafic and felsic, (trondhjemitic) igneous units and black sulfidic schists and quartzites. The dominant lithology is a thinly foliated hbd-plag.-chi-qtz.-Fe carbonate schist with or without hornblende fasicules. Locally, this schist has alternating folia of chl/hbd and plag. and probably has a volcaniclastic protolith. Distinct pillows and tuffs are observed locally. In general, these schists have flat REE patterns at 10X chondrite and plot as IABs on discrimination diagrams. In the eastern part of the Hawley, some amphibolites show concave upward REE patterns, plot in the IAT or boninite field on discriminationmore » diagrams, and appear to have boninitic affinities. The felsic lithologies are trondhjemitic and are intrusive into the IAT/boninite amphibolites. The intrusive nature is based on the presence of mafic xenoliths and intruded rafts of country rock in the trondhjemite as well as the occurrence of thin tabular trondhjemite bodies in sharp contact with the surrounding amphibolite. The trondhjemite varies from coarse-grained weakly foliated qtz-plag.-biotite gneiss with probable relict igneous zoned plagioclases to finer-grained well foliated qtz-plag.-garnet-hbd gneiss. REE patterns for the trondhjemites are weakly U-shaped with moderate to pronounced negative Eu anomalies. The trondhjemites, surrounding amphibolites, and black sulfidic schists and quartzites of the eastern part of the Hawley are intruded by massive, granular, medium grained, plagioclase phenocryst amphibolites with chilled margins. These intrusive sills predate or are coeval with the dominant foliation in the Hawley. Both sills and country rock contain a contact-parallel foliation as well as a later foliation at a low angle to the earlier foliation. The sill amphibolites are high TiO2 high Zr varieties that plot as MORBs to WPBs on discrimination diagrams and exhibit slightly LREE enriched MORB-like to T-MORB REE patterns.« less

The impact of transport processes on rare earth element patterns in marine authigenic and biogenic phosphates

NASA Astrophysics Data System (ADS)

Auer, Gerald; Reuter, Markus; Hauzenberger, Christoph A.; Piller, Werner E.

2017-04-01

Rare earth elements (REEs) are commonly used proxies to reconstruct water chemistry and oxygen saturation during the formation of authigenic and biogenic phosphates in marine environments. In the modern ocean REEs exhibit a distinct pattern with enrichment of heavy REEs and strong depletion in cerium (Ce). The wide range of REE enrichment patterns found in ancient marine phosphates lead to the proposition that water chemistry has been very different in the Earth's past. However, both early and late diagenesis are known to affect REE signatures in phosphates altering primary marine signals. Herein we present a dataset of REE signatures in 38 grain specific LA-ICP-MS measurements of isolated phosphate and carbonate grains in three discrete rock samples. The phosphates mainly consist of authigenic phosphates and phosphatized microfossils that formed in a microbially mediated micro-milieu. In addition, isolated biogenic and reworked phosphatic grains are also present. The phosphates are emplaced in bioclastic grain- to packstones deposited on a carbonate ramp setting in the central Mediterranean Sea during the middle Miocene Monterey event. The results reveal markedly different REE patterns (normalized to the Post Archean Australian Shale standard) in terms of total enrichment and pattern shape. Analyses of REE diagenesis proxies show that diagenetic alteration affected the samples only to a minor degree. Grain shape and REE patterns together indicate that authigenic, biogenic and reworked phosphates have distinct REE patterns irrespective of the sample. Our study shows that while REE patterns in phosphates do reflect water chemistry during authigenesis, they are often already heavily altered during reworking, a process, which can occur in geologically negligible timespans. REE patterns are therefore more likely to reflect complex enrichment processes after their formation. Similarities in the REE patterns of reworked and biogenic phosphate further suggest that the frequently observed hat-shaped pattern in biogenic phosphates can result from increased middle REE (Neodymium to Holmium) scavenging during taphonomic processes prior to final deposition. Cluster analysis coupled with sedimentological and previously published geochemical data (bulk carbon isotope and X-ray fluorescence spectrometry) allowed the characterization of REE patterns of phosphates in terms of their formation conditions and depositional history, such as the distinction of phosphates formed in situ from reworked and transported phosphate grains.

Source and mobility of Rare Earth Elements in a sedimentary aquifer system: Aquitaine basin (Southern France)

NASA Astrophysics Data System (ADS)

Negrel, P. J.; Petelet-Giraud, E.; Millot, R.; Malcuit, E.

2011-12-01

The study of rare earth elements (REEs) in natural waters initially involved an examination of their occurrence and behavior in seawater and coastal waters such as estuaries. Since the 1990s, REE geochemistry has been applied to continental waters such as rivers and lakes and groundwaters. Rare earth elements) are of great interest because of their unique characteristics and have been used in the study of many geological processes like weathering and water-rock interaction processes, provenance of sediments, etc... With the evolution of analytical techniques like new generation ICP-MS, much attention had been paid towards the water geochemistry of REEs. However, there is a need of more investigations devoted to REEs in large groundwater systems, especially on the understanding of the distribution of REEs and their evolution in such systems. In this frame, large sedimentary aquifer systems often constitute strategic water resources for drinking water supply, agriculture irrigation and industry, but can also represent an energetic resource for geothermal power. Large water abstractions can induce complete modification of the natural functioning of such aquifer systems. These large aquifer systems thus require water management at the basin scale in order to preserve both water quantity and quality. The large Eocene Sand aquifer system of the Aquitaine sedimentary basin was studied through various hydrological, chemical and isotopic tools. This system extends over 116,000 km2 in the South west part of the French territory. The aquifer being artesian in the west of the district and confined with piezometric levels around 250-m depth in the east. The 'Eocene Sands', composed of sandy Tertiary sediments alternating with carbonate deposits, is a multi-layer system with high permeability and a thickness of several tens of metres to a hundred metres. The Eocene Sand aquifer system comprises at least five aquifers: Paleocene, Eocene infra-molassic sands (IMS), early Eocene, middle Eocene, and late Eocene. One important feature, in these confined systems isolated from anthropogenic influence, is the range in salinities by a factor of 10, from 250 mg/L up to 2.5 g/L. The ΣREE, in the range 2-54 ng/L, with a dependence on salinity when expressed in % HCO3 or SO4, reflect the carbonate or evaporite source of REEs. The UCC normalized-REE patterns show a large variability as exemplified by the REE flat patterns-low SREE associated with salinity controlled by HCO3. In the present work, the REEs are investigated in terms of saturation indices, speciation modelling, REE patterns in order to recognize the aquifer type hosting groundwater and decipher the origin of the salinity of the groundwater as some part of the aquifer display in the groundwater concentration of chemical element exceeding the drinking water standard (SO4, F...). Such high concentrations of naturally-occurring substances (e.g. unaffected by human activities) can have negative impacts on groundwater thresholds and deciphering their origin by means of geochemical tools like REE is a remaining challenge.

Rare earth and trace element geochemistry of a fragment of Jurassic seafloor, Point Sal, California

NASA Technical Reports Server (NTRS)

Menzies, M.; Blanchard, D.; Brannon, J.; Korotev, R.

1977-01-01

Rocks from an ophiolite suite once on the seafloor were analyzed for rare earth elements (REE), Sc, Co, Na2O, Cr, Zn and FeO. Strontium isotope exchange noted in some of the lavas is attributed to basalt-seawater interaction; the Ce abundance in smectite- and zeolite-bearing lavas may also be due to prolonged exposure to seawater. The higher grades of metamorphic rock, however, show no variation from the usual flat or slightly light REE depleted profiles. Plutonic igneous rock, all light REE depleted, have total REE abundances varying by a factor of 100 between the dunites and diorites. In order of decreasing REE abundance are hornblende, clinopyroxene, plagioclase, orthopyroxene and olivine. Calculations of REE contents of liquids in equilibrium with early cumulative clinopyroxenes suggest that the parent to the stratiform sequence was more depleted in light REE than the parent to the lava pile.

Average sedimentary rock rare Earth element patterns and crustal evolution: Some observations and implications from the 3800 Ma ISUA supracrustal belt, West Greenland

NASA Technical Reports Server (NTRS)

Dymek, R. F.; Boak, J. L.; Gromet, L. P.

1983-01-01

Rare earth element (REE) data is given on a set of clastic metasediments from the 3800 Ma Isua Supracrustal belt, West Greenland. Each of two units from the same sedimentary sequence has a distinctive REE pattern, but the average of these rocks bears a very strong resemblance to the REE pattern for the North American Shale Composite (NASC), and departs considerably from previous estimates of REE patterns in Archaean sediments. The possibility that the source area for the Isua sediments resembled that of the NASC is regarded as highly unlikely. However, REE patterns like that in the NASC may be produced by sedimentary recycling of material yielding patterns such as are found at Isua. The results lead to the following tentative conclusions: (1) The REE patterns for Isua Seq. B MBG indicate the existence of crustal materials with fractionated REE and negative Eu anomalies at 3800 Ma, (2) The average Seq. B REE pattern resembles that of the North American Shale Composite (NASC), (3) If the Seq. B average is truly representative of its crustal sources, then this early crust could have been extensively differentiated. In this regard, a proper understanding of the NASC pattern, and its relationship to post-Archaean crustal REE reservoirs, is essential, (4) The Isua results may represent a local effect.

LA-ICP-MS analysis of isolated phosphatic grains indicates selective rare earth element enrichment during reworking and transport processes

NASA Astrophysics Data System (ADS)

Auer, Gerald; Reuter, Markus; Hauzenberger, Christoph A.; Piller, Werner E.

2016-04-01

Rare earth elements (REE) are a commonly used proxy to reconstruct water chemistry and oxygen saturation during the formation history of authigenic and biogenic phosphates in marine environments. In the modern ocean REE exhibit a distinct pattern with enrichment of heavy REE and strong depletion in Cerium. Studies of ancient phosphates and carbonates, however, showed that this 'modern' pattern is only rarely present in the geological past. Consequently, the wide range of REE enrichment patterns found in ancient marine phosphates lead to the proposition that water chemistry had to have been radically different in the earth's past. A wealth of studies has already shown that both early and late diagenesis can strongly affect REE signatures in phosphates and severely alter primary marine signals. However, no previous research was conducted on how alteration processes occurring prior to final deposition affect marine phosphates. Herein we present a dataset of multiple LA-ICP-MS measurements of REE signatures in isolated phosphate and carbonate grains deposited in a carbonate ramp setting in the central Mediterranean Sea during the middle Miocene "Monterey event". The phosphates are represented by authigenic, biogenic and detrital grains emplaced in bioclastic grain- to packstones dominated by bryozoan and echinoderm fragments, as well as abundant benthic and planktic foraminifers. The results of 39 grain specific LA-ICP-MS measurements in three discrete rock samples reveals four markedly different REE patterns (normalized to the Post Archean Australian Shale standard) in terms of total enrichment and pattern shape. Analyses of REE diagenesis proxies show that diagenetic alteration affected the samples only to a minor degree. Considering grain shape and REE patterns together indicate that authigenic, detrital and biogenic phosphates have distinct REE patterns irrespective of the sample. Our results show that the observed REE patterns in phosphates only broadly reflect water chemistry under certain well constrained circumstances of primary authigenesis. Are these conditions not met, REE patterns are more likely to reflect complex enrichment processes that likely already started to occur during reworking over geologically relatively short time frames. Similarities in the REE patterns of clearly detrital and biogenic phosphate further suggest that the often observed 'hat-shaped' pattern in biogenic phosphates can easily result from increased middle REE (Neodymium to Holmium) scavenging during taphonomic processes prior to final deposition. Finally, cluster analysis coupled with sedimentological considerations proved a valuable tool for the characterization of REE patterns of phosphates in terms of their formation conditions and depositional history, such as the distinction of phosphates formed in situ from reworked and transported phosphate grains.

Geochemical characteristics of aluminum depleted and undepleted komatiites and HREE-enriched low-Ti tholeiites, western Abitibi greenstone belt: A heterogeneous mantle plume-convergent margin environment

NASA Astrophysics Data System (ADS)

Fan, J.; Kerrich, R.

1997-11-01

A compositionally diverse suite of komatiites, komatiitic basalts, and basalts coexist in the Tisdale volcanic assemblage of the late-Archean (˜2.7 Ga) Abitibi greenstone belt. The komatiites are characterized by a spectrum of REE patterns, from low total REE contents (9 ppm) and pronounced convex-up patterns to greater total REE (18 ppm) and approximately flat-distributions. Thorium and niobium are codepleted with LREE. Komatiites with the most convex-up patterns have low Al 2O 3 (4.7 wt%) contents and Al 2O 3/TiO 2(12) ratios; they are interpreted to be the Al-depleted variety of komatiite derived from a depleted mantle source. Those komatiites and komatiitic basalts with flatter REE patterns are characterized by greater Al 2O 3 (7.0 wt%) and near chondritic Al 2O 3/TiO 2 (20) ratios; they are interpreted to be Al-undepleted komatiites generated from trace element undepleted mantle. For the komatiites and komatiitic basalts collectively, Gd/Ybn ratios are negatively correlated with La/Smn, but positively with MgO and Ni. The spectrum of patterns is interpreted as mixing between Al, HREE, Y-depleted, and Sc-depleted komatiites and Al-undepleted komatiites in a heterogeneous mantle plume. Auminum-depleted komatiites are characterized by negative Zr and Hf anomalies, consistent with majorite garnet-liquid D's for HFSE and REEs, signifying melt segregation at depths of >400 km. Tisdale Al-undepleted komatiites and komatiitic basalts have small negative to zero Zr(Hf)/MREE fractionation, signifying melt segregation in or above the garnet stability field. Collectively, the komatiites have correlations of Zr/Zr∗ and Hf/Hf ∗ with Gd/Ybn, and hence the Zr(Hf)/MREE fractionations are unlikely to have stemmed from alteration or crustal contamination. Two types of basalts are present. Type I basalts are Mg-tholeiites with near flat REE and primitive mantle normalized patterns, compositionally similar to abundant Mg-tholeiites associated with both Al-undepleted and Al-depleted komatiites in the Abitibi belt. They have absolute concentrations and ratios of most moderately and highly compatible elements comparable to N- MORB (Zr ˜79 vs. 74, Y ˜30 vs. 28, and Zr/Y = 2.4-2.9 vs. 2.6 ), but are relatively less depleted in highly incompatible elements and lack positive Nb or P anomalies. Type II basalts are relatively aluminous (Al 2O 3 ˜ 16 wt%), with high Al 2O 3/TiO 2 (24-28) ratios. They are characterized by low Th, Nb, and LREE contents at eight to ten times chondrite, with slightly convex-up LREE patterns ( La/Smn = 0.86-0.99 ), but strongly fractionated and enriched HREEs, Y, and Sc, where Gd/Ybn = 0.50-0.55 and consistently positive Zr(Hf)/MREEs anomalies. These basalts are tentatively interpreted as low-Ti tholeiites formed in a convergent margin setting with second stage melting, induced by fluids and melts enriched in incompatible elements and Zr(Hf) relative to MREEs, of a mantle source depleted during first stage melting. They are analogous to the Phanerozoic low-Ti tholeiite - boninite association. Accordingly the Tisdale volcanic sequence records a plume-convergent margin interaction. New analyses of Al-undepleted komatiites from the classical locality at Pyke Hill in Munro Township confirm the presence of small positive anomalies of P, Zr, and Hf, with Zr/Hf ratios generally < 36. These signatures are similar in spinifex and cumulate zones signifying that they are unlikely to have resulted from alteration. The data were generated by INAA and ICP-MS using both HFHNO 3 dissolution and Na 2O 2 sinter. The lack of LREE enrichment with negative Nb, Ta, P, and Ti anomalies in any of the Tisdale or Munro komatiites confirms an intraoceanic setting for the volcanic stage of the Western Abitibi greenstone belt.

The rare-earth elements: Vital to modern technologies and lifestyles

USGS Publications Warehouse

Van Gosen, Bradley S.; Verplanck, Philip L.; Long, Keith R.; Gambogi, Joseph; Seal, Robert R.

2014-01-01

Until recently, the rare-earth elements (REEs) were familiar to a relatively small number of people, such as chemists, geologists, specialized materials scientists, and engineers. In the 21st century, the REEs have gained visibility through many media outlets because of (1) the public has recognized the critical, specialized properties that REEs contribute to modern technology, as well as (2) China's dominance in production and supply of the REEs and (3) international dependence on China for the majority of the world's REE supply.Since the late 1990s, China has provided 85–95 percent of the world’s REEs. In 2010, China announced their intention to reduce REE exports. During this timeframe, REE use increased substantially. REEs are used as components in high technology devices, including smart phones, digital cameras, computer hard disks, fluorescent and light-emitting-diode (LED) lights, flat screen televisions, computer monitors, and electronic displays. Large quantities of some REEs are used in clean energy and defense technologies. Because of the many important uses of REEs, nations dependent on new technologies, such as Japan, the United States, and members of the European Union, reacted with great concern to China’s intent to reduce its REE exports. Consequently, exploration activities intent on discovering economic deposits of REEs and bringing them into production have increased.

Provenance and paleoweathering reconstruction of the Mesoproterozoic Hongshuizhuang Formation (1.4 Ga), northern North China

NASA Astrophysics Data System (ADS)

Luo, Qingyong; Zhong, Ningning; Wang, Yannian; Ma, Ling; Li, Min

2015-10-01

This is the first study presenting major and trace elemental data from the Mesoproterozoic Hongshuizhuang Formation shales in Yanshan basin, North China, in order to reconstruct its provenance and chemical weathering history. The shales are strongly depleted in Na2O and Sr and enriched in Y and transition metal elements relative to upper continental crust. Low Zr concentrations and various discriminant plots (e.g., Th/Sc-Zr/Sc and Al2O3-TiO2-Zr) indicate insignificant mineral sorting or recycling of these shales. The rocks show light rare earth element (REE) enrichment (La/YbCN = 3.99-6.92), flat heavy REE, and significantly negative Eu anomalies (Euan = 0.57-0.68) in chondrite-normalized REE patterns, similar to post-Archean Australian average shales. The fairly uniform REE patterns and trace element ratios indicate that the Hongshuizhuang Formation shales were derived from a felsic source area with granodiorite as the dominant contributor. Mixing calculations suggest a mixture of 30 % granite porphyry, 5 % basalt, and 65 % granodiorite as the possible source of the shales, also supporting that granodiorite was the predominant source. Intense chemical weathering of the source terrain is indicated by high values of the premetasomatized chemical index of alteration, plagioclase index of alteration, Rb/Sr, a strong positive correlation between TiO2 and Al2O3, depletion of CaO, Na2O, and Sr, and mineral compositions. Such strong chemical weathering suggests a warm and wet paleoclimate, perhaps due to high atmospheric CO2 and CH4 concentrations, and a near-equatorial location of the North China Craton in the Columbia supercontinent at 1.4 Ga.

Age and duration of eclogite-facies metamorphism, North Qaidam HP/UHP terrane, Western China

USGS Publications Warehouse

Mattinson, C.G.; Wooden, J.L.; Liou, J.G.; Bird, D.K.; Wu, C.L.

2006-01-01

Amphibolite-facies para-and orthogneisses near Dulan, at the southeast end of the North Qaidam terrane, enclose minor eclogite and peridotite which record ultra-high pressure (UHP) metamorphism associated with the Early Paleozoic continental collision of the Qilian and Qaidam microplates. Field relations and coesite inclusions in zircons from paragneiss suggest that felsic, mafic, and ultramafic rocks all experienced UHP metamorphism and a common amphibolite-facies retrogression. SHRIMP-RG U-Pb and REE analyses of zircons from four eclogites yield weighted mean ages of 449 to 422 Ma, and REE patterns (flat HREE, no Eu anomaly) and inclusions of garnet, omphacite, and rutile indicate these ages record eclogite-facies metamorphism. The coherent field relations of these samples, and the similar range of individual ages in each sample suggests that the ???25 m.y. age range reflects the duration of eclogite-facies conditions in the studied samples. Analyses from zircon cores in one sample yield scattered 433 to 474 Ma ages, reflecting partial overlap on rims, and constrain the minimum age of eclogite protolith crystallization. Inclusions of Th + REE-rich epidote, and zircon REE patterns are consistent with prograde metamorphic growth. In the Lu??liang Shan, approximately 350 km northwest in the North Qaidam terrane, ages interpreted to record eclogite-facies metamorphism of eclogite and garnet peridotite are as old as 495 Ma and as young as 414 Ma, which suggests that processes responsible for extended high-pressure residence are not restricted to the Dulan region. Evidence of prolonged eclogite-facies metamorphism in HP/UHP localities in the Northeast Greenland eclogite province, the Western Gneiss Region of Norway, and the western Alps suggests that long eclogite-facies residence may be globally significant in continental subduction/collision zones.

Climatic and hydrological control on trace element variations in a speleothem from the Chauvet Cave, France

NASA Astrophysics Data System (ADS)

Bourdin, C.; Genty, D.; Douville, E.

2009-04-01

An ICPMS quantitative analysis of Ca, Mg, Ba, Sr, U, Mn, Y and 14 Rare Earth Elements (REE) has been performed on a speleothem from the Chauvet cave (south-east of France). The Chau-stm-6 stalagmite that grew from 33 ky to 11.5 ky before present had been previously dated by U-Th series method and the published d13C and d18O profile is used as a paleoclimatic benchmark. Chau-stm-6 recorded that major element Ca ratios (Mg, Ba, Sr), U and REY (REE + Y) responded to early deglaciation (15 ky). Their concentrations show relative variations of 40% to 75%. Ba and Sr profiles are significantly correlated (r = 0.85) and show a two-step increase during early deglaciation. Mg and U are weakly correlated and display a decreasing trend from 15 ky to 11.5 ky. REY concentrations decrease during early deglaciation (15 ky to 14.5 ky). The clear onset of Younger Dryas as recorded by both d13C and d18O profiles is not well marked by any of these trace elements though the averaged Sr concentration is slightly lower in the more recent part of the profile. Sr and Ba increase is best explained by the tenfold rise of the growth rate rather than changes in water residence time in the karst which would also increase Mg. The incongruent dissolution of dolomite upstream is invalidated by the absence of reported dolomite in the Chauvet karst system. No correlation was found between REY and Mn (an element strongly bound with colloidal and particular phases in water), suggesting that REY were mainly dissolved (and likely to be complexed) in groundwater. Due to the poorly developed soil above the cave, REY are thought to come mainly from the dissolution of the limestone bedrock. Bedrock samples display a rather flat pattern, only slightly depleted in LREE (light REE) and with a weak cerium (Ce) anomaly (0.6 to 1). In comparison Chau-stm-6 patterns show a marked depletion in LREE and a more pronounced Ce anomaly (0.3 to 0.75). This shale-normalized pattern is construed as coming from REY fractionation during mobilization or transport of the elements in seepage water rather than from the mixing of several REY sources. Preferential removal of LREE may come from their stronger affinity with particles and from a weaker carbonate complexation. The different climatic and environmental conditions don't seem to have affected REY fractionation - LREE/HREE (light REE on heavy REE) remained quite constant, although the ratio peaks or fall sharply at the climatic transitions. This could be the result of brief periods of intense leaching of colloids or particles. A weak anticorrelation was found between the Y/REE ratio and Ce anomaly. Moreover glacial conditions correspond to a high Y/REE-low Ce pattern whereas milder climate correspond to the opposite situation. The probable higher concentration of particles during the warmer period could explain both the better transport of REE relative to Y that has a slower particle-reactivity and larger scavenging of all REE that smoothes Ce anomaly. pH and Eh could also control the selective removal of Ce. Again no significant difference between Bolling-Allerod and Younger Dryas samples could be observed on REY patterns. This study is one of the first steps towards the use of REY as paleohydrologic and paleoclimatic proxies in continental environments.

Chemical fluxes and origin of a manganese carbonate-oxide-silicate deposit in bedded chert

USGS Publications Warehouse

Huebner, J.S.; Flohr, M.J.K.; Grossman, J.N.

1992-01-01

Lens-like rhodochrosite-rich bodies within interbedded chert and shale are associated with basalt and/or graywacke in ophiolitic and orogenic zones. The Buckeye manganese mine in the Franciscan Complex of the California Coast Ranges is associated with metagraywacke. Despite blueschist-facies metamorphism, this deposit preserves the compositions and some textural features of its sedimentary protoliths. For this reason, it is a suitable deposit with which to compare more intensely altered deposits, or deposits originating in different paleoenvironments. Six Mn-rich and three Mn-poor minerals form monomineralic layers and mixtures: rhodochrosite, gageite, Mn-oxides (hausmannite, braunite), divalent Mn-silicates (caryopilite, taneyamalite), chlorite, quartz (metachert) and aegirine-augite. The Mn-rich protoliths have high Mn/Fe combined with relatively low concentrations of Ca, Al, Ti, Co, Ni, Cu, Th and REE. REE patterns of various protoliths are distinct. Rhodochrosite and gageite layers are depleted (seawater ?? 5 ?? 104) and flat, whereas patterns of metachert and the Mn-silicate-rich layers mimic the patterns of metashale and metagraywacke (seawater ?? 106). Hausmannite layers have flat patterns (seawater ?? 7 ?? 104) whereas braunite-rich layers are more enriched (seawater ?? 2 ?? 105) and show a distinct positive Ce anomaly. Factor analysis reveals components and fluxes attributed to sub-seafloor fluids (Ni, As, Zn, Sb, W, Mn), seawater (Mg, Au, V, Mo), detritus and veins (Ca, Ba, Sr). Silica is negatively correlated with the sub-seafloor factor. The observed variances indicate that water from the sediment column mixed with seawater, that deposition occurred near the sediment-seawater interface before mixtures of subsurface fluid and seawater homogenized, and that the system was not entirely closed during metamorphism. The variations in REE enrichment can be related to kinetics of deposition: rhodochrosite and gageite were precipitated most rapidly, and therefore were the protoliths that most effectively diluted the REE-rich background resulting from fine clastic material (derived from distal turbidites). The variation of the Ce anomaly and U/Th among diverse lithologies and the differences in Mn oxidation states are consistent with progressive dilution of reduced subsurface fluids with oxidized seawater. By this scheme, rhodochrosite, gageite and hausmannite were deposited from the most reduced fluids, braunite from intermediate mixtures, and Mn-silicates from the sub-seafloor fluids most diluted with fresh seawater. Comparison of the Buckeye with other lens-like and sheet-like deposits having high Mn/Fe and containing Mn3+ and/or Mn2+ suggests that each had three essential fluxes: a sub-seafloor source of Mn, a local source of very soluble silica and a source of relatively fresh, oxygenated water. Additional fluxes, such as clastics, appear to be more characteristic of the paleoenvironment than the three essential fluxes. ?? 1992.

Petrography and the REE-composition of apatite in the Paleoproterozoic Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia

NASA Astrophysics Data System (ADS)

Joosu, Lauri; Lepland, Aivo; Kreitsmann, Timmu; Üpraus, Kärt; Roberts, Nick M. W.; Paiste, Päärn; Martin, Adam P.; Kirsimäe, Kalle

2016-08-01

The first globally significant phosphorous-rich deposits appear in the Paleoproterozoic at around 2 Ga, however, the specific triggers leading to apatite precipitation are debated. We examine phosphorous-rich rocks (up to 8 wt% P2O5) in 1.98-1.92 Ga old Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia. Phosphates in these rocks occur as locally derived and resedimented sand-to-gravel/pebble sized grains consisting of apatite-cemented muddy sediments. Phosphatic grains can be subdivided into four petrographic types (A-D), each has a distinct REE signature reflecting different early-to-late diagenetic conditions and/or metamorphic overprint. Pyrite containing petrographic type D, which typically has a flat REE pattern, negative Ce anomaly and positive Eu anomaly, is the best preserved of the four types and best records conditions present during apatite precipitation. Type D phosphatic grains precipitated under (sub)oxic basinal conditions with a significant hydrothermal influence. These characteristics are similar to Zaonega Formation phosphates of NW Russia's Onega Basin, and consistent with phosphogenesis triggered by the development of anoxic(sulfidic)-(sub)oxic redoxclines at shallow sediment depth during the Paleoproterozoic.

Examination of rare earth element concentration patterns in freshwater fish tissues.

PubMed

Mayfield, David B; Fairbrother, Anne

2015-02-01

Rare earth elements (REEs or lanthanides) were measured in ten freshwater fish species from a reservoir in Washington State (United States). The REE distribution patterns were examined within fillet and whole body tissues for three size classes. Total concentrations (ΣREE) ranged from 0.014 to 3.0 mg kg(-1) (dry weight) and averaged 0.243 mg kg(-1) (dry weight). Tissue concentration patterns indicated that REEs accumulated to a greater extent in organs, viscera, and bone compared to muscle (fillet) tissues. Benthic feeding species (exposed to sediments) exhibited greater concentrations of REEs than pelagic omnivorous or piscivorous fish species. Decreasing REE concentrations were found with increasing age, total length or weight for largescale and longnose suckers, smallmouth bass, and walleye. Concentration patterns in this system were consistent with natural conditions without anthropogenic sources of REEs. These data provide additional reference information with regard to the fate and transport of REEs in freshwater fish tissues in a large aquatic system. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ligand extraction of rare earth elements from aquifer sediments: Implications for rare earth element complexation with organic matter in natural waters

NASA Astrophysics Data System (ADS)

Tang, Jianwu; Johannesson, Karen H.

2010-12-01

The ability of organic matter as well as carbonate ions to extract rare earth elements (REEs) from sandy sediments of a Coastal Plain aquifer was investigated for unpurified organic matter from different sources (i.e., Mississippi River natural organic matter, Aldrich humic acid, Nordic aquatic fulvic acid, Suwannee River fulvic acid, and Suwannee River natural organic matter) and for extraction solutions containing weak (i.e., CH 3COO -) or strong (i.e., CO32-) ligands. The experimental results indicate that, in the absence of strong REE complexing ligands in solution, the amount of REEs released from the sand is small and the fractionation pattern of the released REEs appears to be controlled by the surface stability constants for REE sorption with Fe(III) oxides/oxyhydroxides. In the presence of strong solution complexing ligands, however, the amount and the fractionation pattern of the released REEs reflect the strength and variation of the stability constants of the dominant aqueous REE species across the REE series. The varying amount of REEs extracted by the different organic matter employed in the experiments indicates that organic matter from different sources has different complexing capacity for REEs. However, the fractionation pattern of REEs extracted by the various organic matter used in our experiments is remarkable consistent, being independent of the source and the concentration of organic matter used, as well as solution pH. Because natural aquifer sand and unpurified organic matter were used in our experiments, our experimental conditions are more broadly similar to natural systems than many previous laboratory experiments of REE-humic complexation that employed purified humic substances. Our results suggest that the REE loading effect on REE-humic complexation is negligible in natural waters as more abundant metal cations (e.g., Fe, Al) out-compete REEs for strong binding sites on organic matter. More specifically, our results indicate that REE complexation with organic matter in natural waters is dominated by REE binding to weak sites on dissolved organic matter, which subsequently leads to a middle REE (MREE: Sm-Ho)-enriched fractionation pattern. The experiments also indicate that carbonate ions may effectively compete with fulvic acid in binding with dissolved REEs, but cannot out compete humic acids for REEs. Therefore, in natural waters where low molecular weight (LMW) dissolved organic carbon (DOC) is the predominant form of DOC (e.g., lower Mississippi River water), REEs occur as "truly" dissolved species by complexing with carbonate ions as well as FA, resulting in heavy REE (HREE: Er-Lu)-enriched shale-normalized fractionation patterns. Whereas, in natural terrestrial waters where REE speciation is dominated by organic complexes with high molecular weight DOC (e.g., "colloidal" HA), only MREE-enriched fractionation patterns will be observed because the more abundant, weak sites preferentially complex MREEs relative to HREEs and light REEs (LREEs: La-Nd).

The effect of tissue structure and soil chemistry on trace element uptake in fossils

NASA Astrophysics Data System (ADS)

Hinz, Emily A.; Kohn, Matthew J.

2010-06-01

Trace element profiles for common divalent cations (Sr, Zn, Ba), rare-earth elements (REE), Y, U, and Th were measured in fossil bones and teeth from the c. 25 ka Merrell locality, Montana, USA, by using laser-ablation ICP-MS. Multiple traverses in teeth were transformed into 2-D trace element maps for visualizing structural influences on trace element uptake. Trace element compositions of different soils from the fossil site were also analyzed by solution ICP-MS, employing progressive leaches that included distilled H 2O, 0.1 M acetic acid, and microwave digestion in concentrated HCl-HNO 3. In teeth, trace element uptake in enamel is 2-4 orders of magnitude slower than in dentine, forming an effective trace element barrier. Uptake in dentine parallel to the dentine-enamel interface is enhanced by at least 2 orders of magnitude compared to transverse, causing trace element "plumes" down the tooth core. In bone, U, Ba and Sr are nearly homogeneous, implying diffusivities ˜5 orders of magnitude faster than in enamel and virtually complete equilibration with host soils. In contrast all REE show strong depletions inward, with stepwise linear segments in log-normal or inverse complementary error function plots; these data require a multi-medium diffusion model, with about 2 orders of magnitude difference in slowest vs. fastest diffusivities. Differences in REE diffusivities in bone (slow) vs. dentine (fast) reflect different partition coefficients ( Kd's). Although acid leaches and bulk digestion of soils yield comparable fossil-soil Kd's among different elements, natural solutions are expected to be neutral to slightly basic. Distilled H 2O leachates instead reveal radically different Kd's in bone for REE than for U-Sr-Ba, suggest orders of magnitude lower effective diffusivities for REE, and readily explain steep vs. flat profiles for REE vs. U-Sr-Ba, respectively. Differences among REE Kd's and diffusivities may explain inward changes in Ce anomalies. Acid washes and bulk soil compositions yield misleading Kd's for many trace elements, especially the REE, and H 2O-leaches are preferred. Patterns of trace element distributions indicate diagenetic alteration at all scales, including enamel, and challenge the use of trace elements in paleodietary studies.

Large sedimentary aquifer systems functioning. Constraints by classical isotopic and chemical tools, and REE in the Eocene sand aquifer, SW France

NASA Astrophysics Data System (ADS)

Petelet-Giraud, E.; Negrel, P. J.; Millot, R.; Guerrot, C.; Brenot, A.; Malcuit, E.

2010-12-01

Large sedimentary aquifer systems often constitute strategic water resources for drinking water supply, agriculture irrigation and industry, but can also represent an energetic resource for geothermal power. Large water abstractions can induce complete modification of the natural functioning of such aquifer systems, e.g. with seepage between aquifer layers that can lead to water quality degradation. These large aquifer systems thus require rational water management at the sedimentary basin scale in order to preserve both water quantity and quality. In addition to hydrogeological modelling mainly dealing with water quantity, chemical and isotopic methods were applied to evidence the spatial variability of water characteristics and to turn this into better understanding of hydrosystems functioning. The large Eocene Sand aquifer system of the Adour-Garonne sedimentary basin was studied through various hydrological, chemical and isotopic tools. This system extends over 116,000 km2 (one-fifth of the French territory, located in the South west part). The aquifer being artesian in the west of the district and confined with piezometric levels around 250-m depth in the east. The ‘Eocene Sands’, composed of sandy Tertiary sediments alternating with carbonate deposits, is a multi-layer system with high permeability and a thickness of several tens of metres to a hundred metres..The Eocene Sand aquifer system comprises at least five aquifers: Paleocene, Eocene infra-molassic sands (IMS), early Eocene, middle Eocene, and late Eocene. According to δ18O and δ2H values and estimated 14C ages, both present-day recharge (mainly located in the north of the area) and old recharge (16-35 ky) can be evidenced. High spatial variability was evidenced within a same aquifer layer, with temporal variability over one hydrological cycle limited to a few points located in the recharge areas. These results and especially the very old waters recharged under colder climate combined with the continuous decrease of water levels in the IMS aquifer for instance constitute major indicators to be taken into account for water management at the aquifer system scale. Major elements variability was interpreted in terms of water-rock interactions in these confined systems isolated from anthropogenic influence, with the main role played by evaporites on the water salinity (up to 2.5 g.L-1). Rare Earth Elements (REE) were also analysed in some groundwater samples, resulting in a large variability of UCC normalized-REE patterns, ΣREE ranging from 1.9 to 50.6 µg.L-1, with no dependence on TDS. For instance, interaction with carbonates delivers REE flat patterns and highest ΣREE. The REE patterns and control by key parameters are investigated in order to test REE as a potential supplementary geochemical tracer to recognize the aquifer type hosting groundwater.

Characterization of metal binding sites onto biochar using rare earth elements as a fingerprint.

PubMed

Pourret, Olivier; Houben, David

2018-02-01

The ability of biochar to immobilize metals relies on the amount of functional groups at its surface but the contribution of each functional groups (e.g. carboxylic, phenolic) to metal bonding is poorly known. Using a new approach based on previous works on rare earth element (REE) interactions with humic substances, we aim at elucidating the relative contribution of these binding sites to metal sorption under various conditions (i.e. pH and ionic strengths, IS). Using batch experiments, REE sorption onto biochar was analyzed from pH 3 to 9 and IS 10 -1 mol/L to 10 -3 mol/L. Rare earth element patterns show a Middle REE (MREE) downward concavity at acidic pH and low ionic strength. These patterns are in good agreement with existing datasets quantifying REE binding with humic substances. Indeed, the MREE downward concavity displayed by REE-biochar complexation pattern compares well with REE patterns with various organic compounds. This similarity in the REE complexation pattern shapes suggests that carboxylic groups are the main binding sites of REE in biochar. Overall, our results indicate that the strength of the metal bonding with biochar increases when pH and IS increase, suggesting that biochar is more efficient for long-term metal immobilization at near neutral pH and high ionic strength.

REE Distribution in Cultivated and No Cultivated Soils in Two Viticultural Areas of Central Chile: Mineralogical, Pedological and Anthropic Influences

NASA Astrophysics Data System (ADS)

Castillo, P.; Townley, B.; Aburto, F.

2017-12-01

Within the scope of a Corfo-Innova Project (I+D Wines of Chile-University of Chile) we have recognized remarkable REE patterns in soils of two vineyards located in traditional vinicultural areas: Casablanca and Santa Cruz. Both vineyards have granitic parent rock, with similar petrographic features and REE patterns. We studied REE distribution on twelve cultivated soil profiles at each vineyard, where a full mineralogical, geochemical and pedogenic sampling and characterization was performed. To establish the effect of management no cultivated soil profiles were included from each vineyard location. REE in soil samples were measured by ICP-MS using two digestion methods: lithium metaborate/tetraborate fusion to obtain REE contents in total soil and MMI® partial extraction technique for REE contents on bioavailable phases.Soils display similar signatures of REEs respect to the rock source at both vineyards, but showing relative enrichments in soils of Casablanca and depletion in soils of Santa Cruz. Bioavailable phase data indicates a relative depletion of LREEs compared to HREEs and different anomalies for Ce (positive vs negative) in different areas of the same vineyard. Similar patterns of soils and parent rock suggest that REEs are adequate tracers of lithological source. Enrichments and/or depletions of REE patterns in soils respect to the rock source and Ce anomalies, evidence differential pedogenetic processes occurring at each sampled site. Results of bioavailable phase are coherent with the immobilization and fractionation of LREEs by stable minerals within soils as clays and Fe oxides. Mineralogical results in soil thin sections of Casablanca evidence the occurrence of Ti phases as sphene, ilmenite and rutile, which probably control the relative REE enrichment, since these minerals are considered more stable under pedogenic conditions.Finally, cultivated soils show a depleted but analogous pattern of REE regarding to no cultivated soil, indicating the REEs loss due to agricultural land use. Our preliminary hypothesis is the existence of organometallic complexes that retain REEs in natural soils, which are degraded with vinicultural management. However other factors as differential weathering rates of minerals, clays mineralogy and fractionation of REE by plants must be considered.

Geochemical and Geochronologic Investigations of Zircon-hosted Melt Inclusions in Rhyolites from the Mesoproterozoic Pea Ridge IOA-REE Deposit, St. Francois Mountains, Missouri

NASA Astrophysics Data System (ADS)

Watts, K. E.; Mercer, C. N.; Vazquez, J. A.

2015-12-01

Silicic volcanic and plutonic rocks of an eroded Mesoproterozoic caldera complex were intruded and replaced by iron ore, and cross-cut by REE-enriched breccia pipes (~12% total REO) to form the Pea Ridge iron-oxide-apatite-REE (IOA-REE) deposit. Igneous activity, iron ore formation, and REE mineralization overlapped in space and time, however the source of REEs and other metals (Fe, Cu, Au) integral to these economically important deposits remains unclear. Melt inclusions (MI) hosted in refractory zircon phenocrysts are used to constrain magmatic components and processes in the formation of the Pea Ridge deposit. Homogenized (1.4 kbar, 1000°C, 1 hr) MI in zircons from rhyolites ~600 ft (PR-91) and ~1200 ft (PR-12) laterally from the ore body were analyzed for major elements by EPMA and volatiles and trace elements (H2O, S, F, Cl, REEs, Rb, Sr, Y, Zr, Nb, U, Th) by SHRIMP-RG. Metals (including Cu, Au) will be measured in an upcoming SHRIMP-RG session. U-Pb ages, Ti and REE were determined by SHRIMP-RG for a subset of zircon spots adjacent to MI (1458 ± 18 Ma (PR-12); 1480 ± 45 Ma (PR-91)). MI glasses range from fresh and homogeneous dacite-rhyolite (65-75 wt% SiO2) to heterogeneous, patchy mixtures of K-spar and quartz (PR-12, 91), and more rarely mica, albite and/or anorthoclase (PR-91). MI are commonly attached to monazite and xenotime, particularly along re-entrants and zircon rims (PR-91). Fresh dacite-rhyolite glasses (PR-12) have moderate H2O (~2-2.5 wt%), Rb/Sr ratios (~8) and U (~5-7 ppm), and negative (chondrite-normalized) Eu anomalies (Eu ~0.4-0.7 ppm) (typical of rhyolites), whereas HREEs (Tb, Ho, Tm) are elevated (~2-3 ppm). Patchy K-spar and quartz inclusions (PR-12, 91) have flat LREE patterns, and positive anomalies in Tb, Ho, and Tm. One K-spar inclusion (PR-91) has a ~5-50 fold increase in HREEs (Tb, Dy, Ho, Er, Tm) and U (35 ppm) relative to other MI. U-Pb and REE analyses of its zircon host are not unusual (1484 ± 21 Ma); its irregular shape surrounded by a CL-bright zone (Ti-in-zircon = 713°C) is a commonly observed texture and suggests resorption. Silicic magmatism at Pea Ridge was complex, with zircons trapping both pristine melt and poly-phase mixtures that span a range of REE contents. Most MI have lower REE contents than would be expected for significant magmatic REE contribution to the Pea Ridge IOA-REE deposit.

REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes

USGS Publications Warehouse

Foley, Nora K.; Ayuso, Robert A.; Simandl, G.J.; Neetz, M.

2015-01-01

The Southeastern United States contains numerous anorogenic, or A-type, granites, which constitute promising source rocks for REE-enriched ion adsorption clay deposits due to their inherently high concentrations of REE. These granites have undergone a long history of chemical weathering, resulting in thick granite-derived regoliths, akin to those of South China, which supply virtually all heavy REE and Y, and a significant portion of light REE to global markets. Detailed comparisons of granite regolith profiles formed on the Stewartsville and Striped Rock plutons, and the Robertson River batholith (Virginia) indicate that REE are mobile and can attain grades comparable to those of deposits currently mined in China. A REE-enriched parent, either A-type or I-type (highly fractionated igneous type) granite, is thought to be critical for generating the high concentrations of REE in regolith profiles. One prominent feature we recognize in many granites and mineralized regoliths is the tetrad behaviour displayed in REE chondrite-normalized patterns. Tetrad patterns in granite and regolith result from processes that promote the redistribution, enrichment, and fractionation of REE, such as late- to post- magmatic alteration of granite and silicate hydrolysis in the regolith. Thus, REE patterns showing tetrad effects may be a key for discriminating highly prospective source rocks and regoliths with potential for REE ion adsorption clay deposits.

Alteration geochemistry of the volcanic-hosted Dedeninyurdu, Yergen and Fındıklıyar Cu-Fe mineralization, Northern part of Gökçedoǧan Village, Çorum-Kargi Region, Turkey: Implications for the rare earth elements geochemical characteristics

NASA Astrophysics Data System (ADS)

Ozturk, Sercan; Gumus, Lokman; Abdelnasser, Amr; Yalçin, Cihan; Kumral, Mustafa; Hanilçi, Nurullah

2016-04-01

This study deals with the rare earth element (REE) geochemical behavior the alteration zonesassociated with the volcanic-hosted Cu-Femineralization at the northern part of Gökçedoǧan village, Çorum-Kargi region (N Turkey) which are Dedeninyurdu, Yergen and Fındıklıyar mineralization. The study areacomprises Bekirli Formation, Saraycık Formation, Beşpınar Formation, and Ilgaz Formation. Saraycık Formation consists ofUpper Cretaceous KargıOphiolites, pelagic limestone, siltstone, chert and spilitic volcanic rocks. Fe-Cu mineralization occurred in the spiliticvolcanic rocks of Saraycık Formation representing the host rockand is related with the silicification and sericitizationalteration zones. Dedeninyurdu and Yergen mineralization zone directed nearly N75-80oEis following structural a line but Fındıklıyar mineralization zone has nearly NW direction. The ore mineralogy in these zonesinclude pyrite, chalcopyrite, covellite, hematite with malachite, goethite and a limonite as a result of oxidation. The geochemical characteristics of REE of the least altered spiliticbasalt show flat light and heavy REE with slight positive Eu- and Sr-anomalies according to their chondrite-, N-type MORB, and primitive mantle-normalized REE patterns. While the REE geochemical features of the altered rocks collected from the different alteration zones show that there are negative Eu and Sr anomalies as a result of leaching during the alteration processes.There are positive and negative correlations between K2O index with LREE and HREE, respectively. This is due to the additions of K and La during the alteration processes referring to the pervasive sericitization alteration is the responsible for the Cu-Fe mineralization at the study area. Keywords: Cu-Fe mineralization, Spilitic volcanic rocks, alteration, Rare earth elements (REE) geochemistry.

Lanthanide and actinide chemistry at high C/O ratios in the solar nebula

NASA Technical Reports Server (NTRS)

Lodders, Katharina; Fegley, Bruce, Jr.

1993-01-01

Chemical equilibrium calculations were performed to study the condensation chemistry of the REE and actinides under the highly reducing conditions which are necessary for the formation of the enstatite chondrites. Our calculations confirm that the REE and actinides condensed into oldhamite (CaS), the major REE and actinide host phase in enstatite chondrites, at a carbon-oxygen (C/O) ratio not less than 1 in an otherwise solar gas. Five basic types of REE abundance patterns, several of which are analogous to REE abundance patterns observed in the Ca, Al-rich inclusions in carbonaceous chondrites, are predicted to occur in meteoritic oldhamites. All of the reported REE patterns in oldhamites in enstatite chondrites can be interpreted in terms of our condensation calculations. The observed patterns fall into three of the five predicted categories. The reported Th and U enrichments and ratios in meteoritic oldhamites are also consistent with predictions of the condensation calculations. Pure REE sulfides are predicted to condense in the 10 exp -6 to 10 exp -9 bar range and may be found in enstatite chondrites if they formed in this pressure range.

Hydroxylamine hydrochloride-acetic acid-soluble and -insoluble fractions of pelagic sediment: Readsorption revisited

USGS Publications Warehouse

Piper, D.Z.; Wandless, G.A.

1992-01-01

The extraction of the rare earth elements (REE) from deep-ocean pelagic sediment, using hydroxylamine hydrochloride-acetic acid, leads to the separation of approximately 70% of the bulk REE content into the soluble fraction and 30% into the insoluble fraction. The REE pattern of the soluble fraction, i.e., the content of REE normalized to average shale on an element-by-element basis and plotted against atomic number, resembles the pattern for seawater, whereas the pattern, as well as the absolute concentrations, in the insoluble fraction resembles the North American shale composite. These results preclude significant readsorption of the REE by the insoluble phases during the leaching procedure.

Rare earth element behavior during groundwater – seawater mixing along the Kona Coast of Hawaii

USGS Publications Warehouse

Johannesson, Karen H.; Palmore, C. Dianne; Fackrell, Joseph; Prouty, Nancy G.; Swarzenski, Peter W.; Chevis, Darren A.; Telfeyan, Katherine; White, Christopher D.; Burdige, David J.

2017-01-01

Groundwater and seawater samples were collected from nearshore wells and offshore along the Kona Coast of the Big Island of Hawaii to investigate rare earth element (REE) behavior in local subterranean estuaries. Previous investigations showed that submarine groundwater discharge (SGD) is the predominant flux of terrestrial waters to the coastal ocean along the arid Kona Coast of Hawaii. Groundwater and seawater samples were filtered through 0.45 μm and 0.02 μm pore-size filters to evaluate the importance of colloidal and soluble (i.e., truly dissolved ionic species and/or low molecular weight [LMW] colloids) fractions of the REEs in the local subterranean estuaries. Mixing experiments using groundwater collected immediately down gradient from a wastewater treatment facility (WWTF) proximal to the Kaloko-Hanokohau National Historic Park, and more “pristine” groundwater from a well constructed in a lava tube at Kiholo Bay, were mixed with local seawater to study the effect of solution composition (i.e., pH, salinity) on the concentrations and fractionation behavior of the REEs as groundwater mixes with seawater in Kona Coast subterranean estuaries. The mixed waters were also filtered through 0.45 or 0.02 μm filters to ascertain the behavior of colloidal and soluble fractions of the REEs across the salinity gradient in each mixing experiment. Concentrations of the REEs were statistically identical (two-tailed Student t-test, 95% confidence) between the sequentially filtered sample aliquots, indicating that the REEs occur as dissolved ionic species and/or LMW colloids in Kona Coast groundwaters. The mixing experiments revealed that the REEs are released to solution from suspended particles or colloids when Kona Coast groundwater waters mix with local seawater. The order of release that accompanies increasing pH and salinity follows light REE (LREE) > middle REE (MREE) > heavy REE (HREE). Release of REEs in the mixing experiments is driven by decreases in the free metal ion activity in solution and the concomitant increase in the amount of each REE that occurs in solution as dicarbonato complexes [i.e., Ln(CO3)2-] as pH increases across the salinity gradient. Input-normalized REE patterns of Kona Coast groundwater and coastal seawater are nearly identical and relatively flat compared to North Pacific seawater, indicating that SGD is the chief source of these trace elements to the ocean along the Kona Coast. Additionally, REE concentrations of the coastal seawater are between 10 and 50 times higher than previously reported open-ocean seawater values from the North Pacific, further demonstrating the importance of SGD fluxes of REEs to these coastal waters. Taken together, these observations indicate that large-scale removal of REEs, which characterizes the behavior of REEs in the low salinity reaches of many surface estuaries, is not a feature of the subterranean estuary along the Kona Coast. A large positive gadolinium (Gd) anomaly characterizes groundwater from the vicinity of the WWTF. The positive Gd anomaly can be traced to the coastal ocean, providing further evidence of the impact of SGD on the coastal waters. Estimates of the SGD fluxes of the REEs to the coastal ocean along the Kona Coast (i.e., 1.3 – 2.6 mmol Nd day-1) are similar to recent estimates of SGD fluxes of REEs along Florida’s east coast and to Rhode Island Sound, all of which points to the importance of SGD as significant flux of REEs to the coastal ocean.

Rare earth element behavior during groundwater–seawater mixing along the Kona Coast of Hawaii

DOE PAGES

Johannesson, Karen H.; Palmore, C. Dianne; Fackrell, Joseph; ...

2016-11-14

Groundwater and seawater samples were collected from nearshore wells and offshore along the Kona Coast of the Big Island of Hawaii to investigate rare earth element (REE) behavior in local subterranean estuaries. Previously we saw that submarine groundwater discharge (SGD) is the predominant flux of terrestrial waters to the coastal ocean along the arid Kona Coast of Hawaii. Groundwater and seawater samples were filtered through 0.45 μm and 0.02 μm pore-size filters to evaluate the importance of colloidal and soluble (i.e., truly dissolved ionic species and/or low molecular weight [LMW] colloids) fractions of the REEs in the local subterranean estuaries.more » Mixing experiments using groundwater collected immediately down gradient from a wastewater treatment facility (WWTF) proximal to the Kaloko-Hanokohau National Historic Park, and more “pristine” groundwater from a well constructed in a lava tube at Kiholo Bay, were conducted with local seawater to study the effect of solution composition (i.e., pH, salinity) on the concentrations and fractionation behavior of the REEs as groundwater mixes with seawater in Kona Coast subterranean estuaries. The mixed waters were also filtered through 0.45 or 0.02 μm filters to ascertain the behavior of colloidal and soluble fractions of the REEs across the salinity gradient in each mixing experiment. Concentrations of the REEs were statistically identical (two-tailed Student t-test, 95% confidence) between the sequentially filtered sample aliquots, indicating that the REEs occur as dissolved ionic species and/or LMW colloids in Kona Coast groundwaters. The mixing experiments revealed that the REEs are released to solution from suspended particles or colloids when Kona Coast groundwater waters mix with local seawater. The order of release that accompanies increasing pH and salinity follows light REE (LREE) > middle REE (MREE) > heavy REE (HREE). Release of REEs in the mixing experiments is driven by decreases in the free metal ion activity in solution and the concomitant increase in the amount of each REE that occurs in solution as dicarbonato complexes [i.e., Ln(CO 3) 2 -] as pH increases across the salinity gradient. Input-normalized REE patterns of Kona Coast groundwater and coastal seawater are nearly identical and relatively flat compared to North Pacific seawater, indicating that SGD is the chief source of these trace elements to the ocean along the Kona Coast. Additionally, REE concentrations of the coastal seawater are between 10 and 50 times higher than previously reported open-ocean seawater values from the North Pacific, further demonstrating the importance of SGD fluxes of REEs to these coastal waters. Altogether, these observations indicate that large-scale removal of REEs, which characterizes the behavior of REEs in the low salinity reaches of many surface estuaries, is not a feature of the subterranean estuary along the Kona Coast. A large positive gadolinium (Gd) anomaly characterizes groundwater from the vicinity of the WWTF. The positive Gd anomaly can be traced to the coastal ocean, providing further evidence of the impact of SGD on the coastal waters. Estimates of the SGD fluxes of the REEs to the coastal ocean along the Kona Coast (i.e., 1.3–2.6 mmol Nd day -1) are similar to recent estimates of SGD fluxes of REEs along Florida’s east coast and to Rhode Island Sound, all of which points to the importance of SGD as significant flux of REEs to the coastal ocean.« less

Rare earth element behavior during groundwater–seawater mixing along the Kona Coast of Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johannesson, Karen H.; Palmore, C. Dianne; Fackrell, Joseph

Groundwater and seawater samples were collected from nearshore wells and offshore along the Kona Coast of the Big Island of Hawaii to investigate rare earth element (REE) behavior in local subterranean estuaries. Previously we saw that submarine groundwater discharge (SGD) is the predominant flux of terrestrial waters to the coastal ocean along the arid Kona Coast of Hawaii. Groundwater and seawater samples were filtered through 0.45 μm and 0.02 μm pore-size filters to evaluate the importance of colloidal and soluble (i.e., truly dissolved ionic species and/or low molecular weight [LMW] colloids) fractions of the REEs in the local subterranean estuaries.more » Mixing experiments using groundwater collected immediately down gradient from a wastewater treatment facility (WWTF) proximal to the Kaloko-Hanokohau National Historic Park, and more “pristine” groundwater from a well constructed in a lava tube at Kiholo Bay, were conducted with local seawater to study the effect of solution composition (i.e., pH, salinity) on the concentrations and fractionation behavior of the REEs as groundwater mixes with seawater in Kona Coast subterranean estuaries. The mixed waters were also filtered through 0.45 or 0.02 μm filters to ascertain the behavior of colloidal and soluble fractions of the REEs across the salinity gradient in each mixing experiment. Concentrations of the REEs were statistically identical (two-tailed Student t-test, 95% confidence) between the sequentially filtered sample aliquots, indicating that the REEs occur as dissolved ionic species and/or LMW colloids in Kona Coast groundwaters. The mixing experiments revealed that the REEs are released to solution from suspended particles or colloids when Kona Coast groundwater waters mix with local seawater. The order of release that accompanies increasing pH and salinity follows light REE (LREE) > middle REE (MREE) > heavy REE (HREE). Release of REEs in the mixing experiments is driven by decreases in the free metal ion activity in solution and the concomitant increase in the amount of each REE that occurs in solution as dicarbonato complexes [i.e., Ln(CO 3) 2 -] as pH increases across the salinity gradient. Input-normalized REE patterns of Kona Coast groundwater and coastal seawater are nearly identical and relatively flat compared to North Pacific seawater, indicating that SGD is the chief source of these trace elements to the ocean along the Kona Coast. Additionally, REE concentrations of the coastal seawater are between 10 and 50 times higher than previously reported open-ocean seawater values from the North Pacific, further demonstrating the importance of SGD fluxes of REEs to these coastal waters. Altogether, these observations indicate that large-scale removal of REEs, which characterizes the behavior of REEs in the low salinity reaches of many surface estuaries, is not a feature of the subterranean estuary along the Kona Coast. A large positive gadolinium (Gd) anomaly characterizes groundwater from the vicinity of the WWTF. The positive Gd anomaly can be traced to the coastal ocean, providing further evidence of the impact of SGD on the coastal waters. Estimates of the SGD fluxes of the REEs to the coastal ocean along the Kona Coast (i.e., 1.3–2.6 mmol Nd day -1) are similar to recent estimates of SGD fluxes of REEs along Florida’s east coast and to Rhode Island Sound, all of which points to the importance of SGD as significant flux of REEs to the coastal ocean.« less

Mineralogical controls on mobility of rare earth elements in acid mine drainage environments.

PubMed

Soyol-Erdene, T O; Valente, T; Grande, J A; de la Torre, M L

2018-08-01

Rare earth elements (REE) were analyzed in river waters, acid mine waters, and extracts of secondary precipitates collected in the Iberian Pyrite Belt. The obtained concentrations of the REE in river water and mine waters (acid mine drainage - AMD) were in the range of 0.57 μg/L (Lu) and 2579 μg/L (Ce), which is higher than previously reported in surface waters from the Iberian Pyrite Belt, but are comparable with previous findings from AMD worldwide. Total REE concentrations in river waters were ranged between 297 μg/L (Cobica River) and 7032 μg/L (Trimpancho River) with an average of 2468 μg/L. NASC (North American Shale Composite) normalized REE patterns for river and acid mine waters show clear convex curvatures in middle-REE (MREE) with respect to light- and heavy-REE. During the dissolution experiments of AMD-precipitates, heavy-REE and middle-REE generate the most enriched patterns in the solution. A small number of precipitates did not display MREE enrichment (an index Gd n /Lu n  < 1.0) in NASC normalized pattern and produced relatively lower REE concentrations in extracts. Additionally, very few samples, which mainly contained aluminum sulfates, e.g., pickeringite and alunogen, displayed light-REE enrichment relative to heavy-REE (HREE). In general, the highest retention of REE occurs in samples enriched in magnesium (epsomite or hexahydrite) and aluminum sulfates, mainly pickeringite. Copyright © 2018 Elsevier Ltd. All rights reserved.

Recovery and Separation of Rare Earth Elements Using Salmon Milt

PubMed Central

Takahashi, Yoshio; Kondo, Kazuhiro; Miyaji, Asami; Watanabe, Yusuke; Fan, Qiaohui; Honma, Tetsuo; Tanaka, Kazuya

2014-01-01

Recycling rare earth elements (REEs) used in advanced materials such as Nd magnets is important for the efficient use of REE resources when the supply of several REEs is limited. In this work, the feasibility of using salmon milt for REE recovery and separation was examined, along with the identification of the binding site of REEs in salmon milt. Results showed that (i) salmon milt has a sufficiently high affinity to adsorb REEs and (ii) the adsorption capacity of the milt is 1.04 mEq/g, which is comparable with that of commercial cation exchange resin. Heavier REEs have higher affinity for milt. A comparison of stability constants and adsorption patterns of REEs discussed in the literature suggests that the phosphate is responsible for the adsorption of REE in milt. The results were supported by dysprosium (Dy) and lutetium (Lu) LIII-edge extended x-ray absorption fine structure (EXAFS) spectroscopy. The REE-P shell was identified for the second neighboring atom, which shows the importance of the phosphate site as REE binding sites. The comparison of REE adsorption pattern and EXAFS results between the milt system and other adsorbent systems (cellulose phosphate, Ln-resin, bacteria, and DNA-filter hybrid) revealed that the coordination number of phosphate is correlated with the slope of the REE pattern. The separation column loaded with milt was tested to separate REE for the practical use of salmon milt for the recovery and separation of REE. However, water did not flow through the column possibly because of the hydrophobicity of the milt. Thus, sequential adsorption–desorption approach using a batch-type method was applied for the separation of REE. As an example of the practical applications of REE separation, Nd and Fe(III) were successfully separated from a synthetic solution of Nd magnet waste by a batch-type method using salmon milt. PMID:25490035

Rare earth element compositions of core sediments from the shelf of the South Sea, Korea: Their controls and origins

NASA Astrophysics Data System (ADS)

Jung, Hoi-Soo; Lim, Dhongil; Choi, Jin-Yong; Yoo, Hae-Soo; Rho, Kyung-Chan; Lee, Hyun-Bok

2012-10-01

Rare earth elements (REEs) of bulk sediments and heavy mineral samples of core sediments from the South Sea shelf, Korea, were analyzed to determine the constraints on REE concentrations and distribution patterns as well as to investigate their potential applicability for discriminating sediment provenance. Bulk sediment REEs showed large variation in concentrations and distribution patterns primarily due to grain size and carbonate dilution effects, as well as due to an abundance of heavy minerals. In the fine sandy sediments (cores EZ02-15 and 19), in particular, heavy minerals (primarily monazite and titanite/sphene) largely influenced REE compositions. Upper continental crust-normalized REE patterns of these sand-dominated sediments are characterized by enriched light REEs (LREEs), because of inclusion of heavy minerals with very high concentrations in LREEs. Notably, such a strong LREE enrichment is also observed in Korean river sediments. So, a great care must be taken when using the REE concentrations and distribution patterns of sandy and coarse silty shelf sediments as a proxy for discriminating sediment provenance. In the fine-grained muddy sediments with low heavy mineral abundance, in contrast, REE fractionation ratios and their UCC-normalized patterns seem to be reliable proxies for assessing sediment provenance. The resultant sediment origin suggested a long lateral transportation of some fine-grained Chinese river sediments (probably the Changjiang River) to the South Sea of Korea across the shelf of the northern East China Sea.

Seasonal sedimentary processes of the macrotidal flat in Gomso Bay, west coast of Korea

NASA Astrophysics Data System (ADS)

Woo, H.; Kang, J.; Choi, J.

2012-12-01

The tidal flats on the west coast of Korea have broad zones with gentle slopes and a macrotidal setting with 4 to 10 meters of tidal ranges. They are directly influenced by monsoons and heavily affected by waves in winter and tidal currents in summer. As a result, most western tidal flats show the seasonal changes of sedimentary features comprising sedimentation and/or erosion of sediments. Gomso bay in the mid-west of Korea is a funnel-shaped embayment with a wide entrance to the west. Tides are semidiurnal and macrotidal, with a mean tidal range of 433.8 cm. Digital elevation model (DEM) showed that the landward inner bay had mainly high elevations and the seaward outer bay had relatively low elevations. In particular, there are considerable gradients in the outer bay from area of high-water line to area of low-water line. The sedimentary analysis and monitoring short-term sedimentation rates were investigated to understand seasonal sedimentary processes of tidal flats in Gomso bay. The surface sediments in the bay were classified into five sedimentary facies in spring 2011. Generally, sandy sediments were dominated in the outer bay, whereas sandy mud sediments were distributed on the inner bay. The middle bay mainly consisted of muddy sand sediments. The percentages of sand decreased from outer to inner bay. The short-term sedimentation rates were obtained from three lines by burying a plate at sub-bottom depth and periodically measuring the changing sediment depth from February 2011 to February 2012. In the tidal flat at inner bay (KB- Line), the annual sedimentation rates were ranged -8.87 to 74.69 mm/year with the net deposition rate of 40.90 mm/year. The deposition occurred on KB-Line in spring, autumn and winter. The erosion was dominated on the tidal flats at middle (KH-Line) and outer bay (KM-Line) during autumn and winter with an annual erosion rate of -29.86 mm/year and -9.92 mm/year, respectively. The seasonal variations of sedimentation on these tidal flats showed that the deposition occurred with an inflow of muddy sediments in summer, whereas the erosion was dominated in autumn and winter. In August 2011, the distribution patterns of rare earth elements (REEs) relative to the upper continental crust (UCC) showed the enrichment of light REEs (LREEs: La-Nd), together with an apparent depletion of Eu in the KH- and KM-Lines. This pattern was more pronounced in the middle bay sediments (KH-Line) due to influence of muddy sediment transport from Jujin Stream during the rainy period (July and August). On the other hand, the outer bay sediments in the KM-Line were reflected more inflow of second sediment source, the Geum River. The major control factors for seasonal variations of sediments on the tidal flat could be heavy rainfall and tidal currents during summer and strong waves during winter. The net sedimentation showed that the deposition occurred in the inner tidal flat and erosion occurred in the middle and outer tidal flat of the bay.

Trace-element abundances in several new ureilites

NASA Technical Reports Server (NTRS)

Boynton, William V.; Hill, Dolores H.

1993-01-01

Four new ureilites are analyzed for trace-element abundances. Frontier Mountain (FRO) 90054 is an augite-rich ureilite and has high rare earth element (REE) abundances with a pattern expected of augite. FRO 90036 and Acfer 277 have REE patterns similar to the V-shape pattern of other ureilites. Nuevo Mercurio (b) has very high REE abundances, but they look like they are due to terrestrial alteration. The siderophile-element pattern of these ureilites are similar to those of known ureilites.

Thermal effects on rare earth element and strontium isotope chemistry in single conodont elements

NASA Astrophysics Data System (ADS)

Armstrong, H. A.; Pearson, D. G.; Griselin, M.

2001-02-01

A low-blank, high sensitivity isotope dilution, ICP-MS analytical technique has been used to obtain REE abundance data from single conodont elements weighing as little as 5 μg. Sr isotopes can also be measured from the column eluants enabling Sr isotope ratios and REE abundance to be determined from the same dissolution. Results are comparable to published analyses comprising tens to hundreds of elements. To study the effects of thermal metamorphism on REE and strontium mobility in conodonts, samples were selected from a single bed adjacent to a basaltic dyke and from the internationally used colour alteration index (CAI) "standard set." Our analyses span the range of CAI 1 to 8. Homogeneous REE patterns, "bell-shaped" shale-normalised REE patterns are observed across the range of CAI 1 to 6 in both sample sets. This pattern is interpreted as the result of adsorption during early diagenesis and could reflect original seawater chemistry. Above CAI 6 REE patterns become less predictable and perturbations from the typical REE pattern are likely to be due to the onset of apatite recrystallisation. Samples outside the contact aureole of the dyke have a mean 87Sr/ 86Sr ratio of 0.708165, within the broad range of published mid-Carboniferous seawater values. Our analysis indicates conodonts up to CAI 6 record primary geochemical signals that may be a proxy for ancient seawater.

Rare earth elements distribution in grapevine varieties grown on volcanic soils: an example from Mount Etna (Sicily, Italy).

PubMed

D'Antone, Carmelisa; Punturo, Rosalda; Vaccaro, Carmela

2017-04-01

A geochemical and statistical approach has allowed identifying in rare earth elements (REEs) absorption a good fingerprinting mark for determining the territoriality and the provenance of Vitis vinifera L. in the district of Mount Etna (southern Italy). Our aim is to define the REEs distribution in different parts of the plants which grow in the same volcanic soil and under the same climate conditions, and therefore to assess whether REEs distribution may reflect the composition of the provenance soil or if plants can selectively absorb REEs in order to recognize the fingerprint in the Etna Volcano soils as well as the REEs pattern characteristic of each cultivar of V. vinifera L. The characteristic pattern of REEs has been determined by ICP-MS analyses in the soils and in the selected grapevine varieties for all the following parts: leaves, seeds, juice, skin, and berries. These geochemical criteria, together with the multivariate statistical analysis of the principal component analysis (PCA) and of the linear discriminant analysis (LDA) that can be summarized with the box plot, suggest that leaves mostly absorb REEs than the other parts of the plant. This work investigates the various parts of the plant in order to verify if each grape variety presents a characteristic geochemical pattern in the absorption of REEs in relationship with the geochemical features of the soil so to highlight the individual compositional fingerprint. Based on REE patterns, our study is a useful tool that allows characterizing the differences among the grape varieties and lays the foundation for the use of REEs in the geographic origin of the Mount Etna wine district.

Time-resolved interaction of seawater with gabbro: An experimental study of rare-earth element behavior up to 475 °C, 100 MPa

NASA Astrophysics Data System (ADS)

Beermann, Oliver; Garbe-Schönberg, Dieter; Bach, Wolfgang; Holzheid, Astrid

2017-01-01

High metal and rare-earth element (REE) concentrations with unusual ('atypical') normalized REE patterns are documented in fluids from active hydrothermal vent fields on the Mid-Atlantic Ridge, 5°S and the East Scotia Ridge. Those fluids show relative enrichment of middle heavy REEs and almost no Eu anomalies in chondrite-normalized patterns. To understand the processes that produce such atypical REE patterns we ran a series of experiments, in which natural bottom seawater or aqueous solutions (NaCl, NaCl-MgCl2, or NaCl-CaCl2) were reacted with gabbro and gabbro mineral assemblages from 300 to 475 °C and 40 and 100 MPa. These P-T conditions are representative for water-rock interactions in hydrothermal root and discharge zones. Fluid flux variability and kinetics were addressed in the experiments by varying the water-to-rock mass ratio (w/r) from 0.5-10 and using different run durations from 3-720 h. Only seawater and synthetic MgCl2-bearing fluid mobilized significant amounts of REEs, Si, Ca, Fe, and Mn from gabbro, from clinopyroxene, and from plagioclase. At 425 °C and 40 MPa, fluids were initially acidic with pH (25 °C) of ∼2 increasing to values between ∼4 and 7 upon progressing reactions. Rare earth element and Fe contents peaked within 3-6 h after interaction with gabbroic mineral grains (125-500 μm) at w/r of 5 (REEs) and 2-5 (Fe) but decreased with continuing reaction without strong REE fractionation. Most of the REEs that were leached from primary minerals and dissolved in the fluids early became redeposited into solid reaction products after 720 h. Contents of dissolved SiO2 were pressure-dependent, being about twofold higher at 100 MPa than at 40 MPa (425 °C) and were below quartz saturation with gabbro and clinopyroxene as solid starting material and close to quartz saturation with plagioclase reactant. However, Si in fluids from the rock-dominated experiments at 100 MPa with gabbro (w/r 0.5-1) dropped to very low contents. A concomitant decrease in chlorinity suggests that these changes may be due to the breakdown of olivine and the formation of serpentine and Fe-hydroxy chlorides. Regardless of the starting solid reactants, fluid REE patterns were dominantly controlled by w/r. Atypical fluid REE patterns and high fluid REE contents were obtained at high w/r (⩾5). Whereas typical REE patterns known from many mid-ocean ridge vent fluids, showing relative enrichments of light REEs and a positive Eu anomaly, were obtained at low w/r of 0.5-1. Our results hence clearly show that REE contents and patterns of vent fluids are sensitive to variations in the w/r.

Rare earth element geochemistry of oceanic ferromanganese nodules and associated sediments

NASA Astrophysics Data System (ADS)

Elderfield, H.; Hawkesworth, C. J.; Greaves, M. J.; Calvert, S. E.

1981-04-01

Analyses have been made of REE contents of a well-characterized suite of deep-sea (> 4000 m.) principally todorokite-bearing ferromanganese nodules and associated sediments from the Pacific Ocean. REE in nodules and their sediments are closely related: nodules with the largest positive Ce anomalies are found on sediments with the smallest negative Ce anomalies; in contrast, nodules with the highest contents of other rare earths (3 + REE) are found on sediments with the lowest 3 + REE contents and vice versa. 143Nd /144Nd ratios in the nodules (˜0.51244) point to an original seawater source but an identical ratio for sediments in combination with the REE patterns suggests that diagenetic reactions may transfer elements into the nodules. Analysis of biogenic phases shows that the direct contribution of plankton and carbonate and siliceous skeletal materials to REE contents of nodules and sediments is negligible. Inter-element relationships and leaching tests suggest that REE contents are controlled by a P-rich phase with a REE pattern similar to that for biogenous apatite and an Fe-rich phase with a pattern the mirror image of that for sea water. It is proposed that 3 + REE concentrations are controlled by the surface chemistry of these phases during diagenetic reactions which vary with sediment accumulation rate. Processes which favour the enrichment of transition metals in equatorial Pacific nodules favour the depletion of 3 + REE in nodules and enrichment of 3 + REE in associated sediments. In contrast, Ce appears to be added both to nodules and sediments directly from seawater and is not involved in diagenetic reactions.

Origin of the anomalies in light and middle REE in sediments of an estuary affected by phosphogypsum wastes (south-western Spain).

PubMed

Borrego, J; López-González, N; Carro, B; Lozano-Soria, O

2004-12-01

Sc, Y, Th, Cu and rare earth elements (REE) concentrations have been analyzed in 14 samples of surface sediments and in two gravity cores by means of ICP-MS. Mean concentrations of Sc, Y and Th in surface sediments are 6.23, 4.76 and 16.30 ppm, respectively, lower than those present in the Upper Continental Crust (UCC). Cu concentration in these sediments is very high, 1466 ppm, and is caused by inputs from the Odiel and Tinto rivers, affected by acid mine drainage. SigmaREE mean concentration is 106.8 ppm, lower than that observed in other rivers and estuaries. In the cores, Sc, Y and Th concentrations show a significant increase in the intermediate levels, between 10 and 40 cm depth. The same pattern exists with Cu, where concentrations of 4440 ppm can be reached. Vertical evolution patterns for Sc, Y, Cu and heavy REE (HREE) are similar, and contrary to those shown by Th, light REE (LREE) and middle REE (MREE). Plots of North American Shale Composite (NASC)-normalized REE data of surface sediments show a slight depletion in REE concentrations. Most samples present with middle REE enrichment relative to light REE and heavy REE. Conversely, samples of the intermediate levels of the cores show significant enrichment of REE relative to NASC and high values in the (La/Gd)NASC and (La/Yb)NASC ratios. These anomalies in the fractionation patterns caused by enrichments in LREE and MREE concentrations is related to the presence of high concentrations of Th. They were generated by effluents from fertilizer factories between 1968 and 1998 which used phosphorite as source material.

A first report of rare earth elements in northwestern Mediterranean seaweeds.

PubMed

Squadrone, Stefania; Brizio, Paola; Battuello, Marco; Nurra, Nicola; Sartor, Rocco Mussat; Benedetto, Alessandro; Pessani, Daniela; Abete, Maria Cesarina

2017-09-15

The concentrations of rare earth elements (REE) were determined by ICP-MS in dominant seaweed species, collected from three locations of the northwestern Mediterranean Sea. This is the first study to define levels and patterns of REE in macro algae from these coastal areas. Rare elements are becoming emerging inorganic contaminants in marine ecosystems, due to their worldwide increasing applications in industry, technology, medicine and agriculture. Significant inter-site and interspecies differences were registered, with higher levels of REE in brown and green macro algae than in red seaweeds. Levels of light REE were also observed to be greater compared to heavy REE in all samples. One of the investigated locations (Bergeggi, SV) had higher REE and ΣREE concentrations, probably due to its proximity to an important commercial and touristic harbor, while the other two sites were less affected by anthropogenic contaminations, and showed comparable REE patterns and lower concentrations. Rare earth elements in seaweeds. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Northeast Kingdom batholith, Vermont: magmatic evolution and geochemical constraints on the origin of Acadian granitic rocks

USGS Publications Warehouse

Ayuso, R.A.; Arth, Joseph G.

1992-01-01

Five Devonian plutons (West Charleston, Echo Pond, Nulhegan, Derby, and Willoughby) that constitute the Northeast Kingdom batholith in Vermont show wide ranges in elemental abundances and ratios consistent with major crustal contributions during their evolution. The batholith consists of metaluminous quartz gabbro, diorite and quartz monzodiorite, peraluminous granodiorite and granite, and strongly peraluminous leucogranite. Contents of major elements vary systematically with increasingSiO40) and have small negative Eu anomalies. The strongly peraluminous Willoughby leucogranite has unique trace-element abundances and ratios relative to the rest of the batholith, including low contents of Hf, Zr, Sr, and Ba, low values of K/Rb (80-164), Th/Ta (<9), Rb/Cs (7-40), K/Cs (0.1-0.5), Ce/Pb (0.5-4), high values of Rb/Sr (1-18) low to moderate REE contents and light-REE enriched patterns (with small negative Eu anomalies). Flat REE patterns (with large negative Eu anomalies) are found in a small, hydrothermally-altered area characterized by high abundances of Sn (up to 26 ppm), Rb (up to 670 ppm), Li (up to 310 ppm), Ta (up to 13.1 ppm), and U (up to 10 ppm). There is no single mixing trend, fractional crystallization assemblage, or assimilationscheme that accounts for all trace elementvariations from quartz gabbro to granite in the Northeast Kingdom batholith. The plutons originated by mixing mantle-derived components and crustal melts generated at different levels in the heterogeneous lithosphere in a continental collisional environment. Hybrid rocks in the batholith evolved by fractional crystallization and assimilation of country rocks (<50% by mass), and some of the leucogranitic rocks were subsequently disturbed by a mild hydrothermal event that resulted in the deposition of small amounts of sulfide minerals. ?? 1992 Springer-Verlag.

Mineralogy, geochemistry, and radiocarbon ages of deep sea sediments from the Gulf of Mexico, Mexico

NASA Astrophysics Data System (ADS)

Armstrong-Altrin, John S.; Machain-Castillo, María Luisa

2016-11-01

The mineralogy, geochemistry, and radiocarbon ages of two sediment cores (GMX1 and GMX2) collected from the deep sea area of the Southwestern Gulf of Mexico (∼876-1752 m water depth) were studied to infer the sedimentation rate, provenance, heavy metal contamination, and depositional environment. The sediments are dominated by silt and clay fractions. The mineralogy determined by X-Ray diffractometry for the sediment cores reveals that montmorillonite and muscovite are the dominant clay minerals. The sections between 100 and 210 cm of the sediment cores GMX1 and GMX2, respectively, are characterized by the G. menardii group and G. Inflata planktonic foraminiferal species, which represent the Holocene and Pleistocene, respectively. The radiocarbon-age measurements of mixed planktonic foraminifera varied from ∼268 to 45,738 cal. years B.P and ∼104 to 25,705 cal. years B.P, for the sediment cores GMX1 and GMX2, respectively. The variation in age between the two sediment cores is due to a change in sediment accumulation rate, which was lowest at the location GMX1 (0.006 cm/yr) and highest at the location GMX2 (0.017 cm/yr). The chemical index of alteration (CIA), chemical index of weathering (CIW), and index of chemical maturity (ICV) values indicated a moderate intensity of weathering in the source area. The total rare earth element concentrations (∑REE) in the cores GMX1 and GMX2 vary from ∼94 to 171 and ∼78 to 151, respectively. The North American Shale Composite (NASC) normalized REE patterns showed flat low REE (LREE), heavy REE (HREE) depletion with low negative to positive Eu anomalies, which suggested that the sediments were likely derived from intermediate source rocks. The enrichment factor of heavy metals indicated that the Cd and Zn concentrations in the sediment cores were impacted by an anthropogenic source. The redox-proxy trace element ratios such as V/Cr, Ni/Co, Cu/Zn, (Cu + Mo)/Zn, and Ce/Ce* indicated that the sediments were deposited under an oxic depositional environment. The similarity in major element concentrations, REE content, and the NASC normalised REE patterns between the cores GMX1 and GMX2 revealed that the provenance of sediments remained relatively uniform or constant during deposition for ∼4.5 Ma. The major and trace element based multidimensional discrimination diagrams showed a rift setting for the core sediments, which is consistent with the geology of the Gulf of Mexico.

Determination of zircon/melt trace element partition coefficients from SIMS analysis of melt inclusions in zircon

NASA Astrophysics Data System (ADS)

Thomas, J. B.; Bodnar, R. J.; Shimizu, N.; Sinha, A. K.

2002-09-01

Partition coefficients ( zircon/meltD M) for rare earth elements (REE) (La, Ce, Nd, Sm, Dy, Er and Yb) and other trace elements (Ba, Rb, B, Sr, Ti, Y and Nb) between zircon and melt have been calculated from secondary ion mass spectrometric (SIMS) analyses of zircon/melt inclusion pairs. The melt inclusion-mineral (MIM) technique shows that D REE increase in compatibility with increasing atomic number, similar to results of previous studies. However, D REE determined using the MIM technique are, in general, lower than previously reported values. Calculated D REE indicate that light REE with atomic numbers less than Sm are incompatible in zircon and become more incompatible with decreasing atomic number. This behavior is in contrast to most previously published results which indicate D > 1 and define a flat partitioning pattern for elements from La through Sm. The partition coefficients for the heavy REE determined using the MIM technique are lower than previously published results by factors of ≈15 to 20 but follow a similar trend. These differences are thought to reflect the effects of mineral and/or glass contaminants in samples from earlier studies which employed bulk analysis techniques. D REE determined using the MIM technique agree well with values predicted using the equations of Brice (1975), which are based on the size and elasticity of crystallographic sites. The presence of Ce 4+ in the melt results in elevated D Ce compared to neighboring REE due to the similar valence and size of Ce 4+ and Zr 4+. Predicted zircon/meltD values for Ce 4+ and Ce 3+ indicate that the Ce 4+/Ce 3+ ratios of the melt ranged from about 10 -3 to 10 -2. Partition coefficients for other trace elements determined in this study increase in compatibility in the order Ba < Rb < B < Sr < Ti < Y < Nb, with Ba, Rb, B and Sr showing incompatible behavior (D M < 1.0), and Ti, Y and Nb showing compatible behavior (D M > 1.0). The effect of partition coefficients on melt evolution during petrogenetic modeling was examined using partition coefficients determined in this study and compared to trends obtained using published partition coefficients. The lower D REE determined in this study result in smaller REE bulk distribution coefficients, for a given mineral assemblage, compared to those calculated using previously reported values. As an example, fractional crystallization of an assemblage composed of 35% hornblende, 64.5% plagioclase and 0.5% zircon produces a melt that becomes increasingly more enriched in Yb using the D Yb from this study. Using D Yb from Fujimaki (1986) results in a melt that becomes progressively depleted in Yb during crystallization.

Origin of middle rare earth element enrichments in acid waters of a Canadian high Arctic lake.

NASA Astrophysics Data System (ADS)

Johannesson, Kevin H.; Zhou, Xiaoping

1999-01-01

-Middle rare earth element (MREE) enriched rock-normalized rare earth element (REE) patterns of a dilute acidic lake (Colour Lake) in the Canadian High Arctic, were investigated by quantifying whole-rock REE concentrations of rock samples collected from the catchment basin, as well as determining the acid leachable REE fraction of these rocks. An aliquot of each rock sample was leached with 1 N HNO 3 to examine the readily leachable REE fraction of each rock, and an additional aliquot was leached with a 0.04 M NH 2OH · HCl in 25% (v/v) CH 3COOH solution, designed specifically to reduce Fe-Mn oxides/oxyhydroxides. Rare earth elements associated with the leachates that reacted with clastic sedimentary rock samples containing petrographically identifiable Fe-Mn oxide/oxyhydroxide cements and/or minerals/amorphous phases, exhibited whole-rock-normalized REE patterns similar to the lake waters, whereas whole-rock-normalized leachates from mafic igneous rocks and other clastic sedimentary rocks from the catchment basin differed substantially from the lake waters. The whole-rock, leachates, and lake water REE data support acid leaching or dissolution of MREE enriched Fe-Mn oxides/oxyhydroxides contained and identified within some of the catchment basin sedimentary rocks as the likely source of the unique lake water REE patterns. Solution complexation modelling of the REEs in the inflow streams and lake waters indicate that free metal ions (e.g., Ln 3+, where Ln = any REE) and sulfate complexes (LnSO 4+) are the dominant forms of dissolved REEs. Consequently, solution complexation reactions involving the REEs during weathering, transport to the lake, or within the lake, cannot be invoked to explain the MREE enrichments observed in the lake waters.

Rare earth elements in river waters

NASA Technical Reports Server (NTRS)

Goldstein, Steven J.; Jacobsen, Stein B.

1988-01-01

To characterize the input to the oceans of rare earth elements (REE) in the dissolved and the suspended loads of rivers, the REE concentrations were measured in samples of Amazon, Indus, Mississippi, Murray-Darling, and Ohio rivers and in samples of smaller rivers that had more distinct drainage basin lithology and water chemistry. It was found that, in the suspended loads of small rivers, the REE pattern was dependent on drainage basin geology, whereas the suspended loads in major rivers had relatively uniform REE patterns and were heavy-REE depleted relative to the North American Shale composite (NASC). The dissolved loads in the five major rivers had marked relative heavy-REE enrichments, relative to the NASC and the suspended material, with the (La/Yb)N ratio of about 0.4 (as compared with the ratio of about 1.9 in suspended loads).

Rare earth elements in freshwater, marine, and terrestrial ecosystems in the eastern Canadian Arctic.

PubMed

MacMillan, Gwyneth Anne; Chételat, John; Heath, Joel P; Mickpegak, Raymond; Amyot, Marc

2017-10-18

Few ecotoxicological studies exist for rare earth elements (REEs), particularly field-based studies on their bioaccumulation and food web dynamics. REE mining has led to significant environmental impacts in several countries (China, Brazil, U.S.), yet little is known about the fate and transport of these contaminants of emerging concern. Northern ecosystems are potentially vulnerable to REE enrichment from prospective mining projects at high latitudes. To understand how REEs behave in remote northern food webs, we measured REE concentrations and carbon and nitrogen stable isotope ratios (∂ 15 N, ∂ 13 C) in biota from marine, freshwater, and terrestrial ecosystems of the eastern Canadian Arctic (N = 339). Wildlife harvesting and tissue sampling was partly conducted by local hunters through a community-based monitoring project. Results show that REEs generally follow a coherent bioaccumulation pattern for sample tissues, with some anomalies for redox-sensitive elements (Ce, Eu). Highest REE concentrations were found at low trophic levels, especially in vegetation and aquatic invertebrates. Terrestrial herbivores, ringed seal, and fish had low total REE levels in muscle tissue (∑REE for 15 elements <0.1 nmol g -1 ), yet accumulation was an order of magnitude higher in liver tissues. Age- and length-dependent REE accumulation also suggest that REE uptake is faster than elimination for some species. Overall, REE bioaccumulation patterns appear to be species- and tissue-specific, with limited potential for biomagnification. This study provides novel data on the behaviour of REEs in ecosystems and will be useful for environmental impact assessment of REE enrichment in northern regions.

Rare earths in the Leadville Limestone and its marble derivates

USGS Publications Warehouse

Jarvis, J.C.; Wildeman, T.R.; Banks, N.G.

1975-01-01

Samples of unaltered and metamorphosed Leadville Limestone (Mississippian, Colorado) were analyzed by neutron activation for ten rare-earth elements (REE). The total abundance of the REE in the least-altered limestone is 4-12 ppm, and their distribution patterns are believed to be dominated by the carbonate minerals. The abundances of the REE in the marbles and their sedimentary precursors are comparable, but the distribution patterns are not. Eu is enriched over the other REE in the marbles, and stratigraphically upward in the formation (samples located progressively further from the heat source), the light REE become less enriched relative to the heavy REE. The Eu anomaly is attributed to its ability, unique among the REE, to change from the 3+ to 2+ oxidation state. Whether this results in preferential mobilization of the other REE or whether this reflects the composition of the pore fluid during metamorphism is unknown. Stratigraphically selective depletion of the heavy REE may be attributed to more competition for the REE between fluid and carbonate minerals in the lower strata relative to the upper strata. This competition could have been caused by changes in the temperature of the pore fluid or to the greater resistance to solution of the dolomite in the lower parts of the formation than the calcite in the upper parts. ?? 1975.

Rare Earth Element Measurements of Melilite and Fassaite in Allende Cai by Nanosims

NASA Technical Reports Server (NTRS)

Ito, M.; Messenger, Scott

2009-01-01

The rare earth elements (REEs) are concentrated in CAIs by approx. 20 times the chondritic average [e.g., 1]. The REEs in CAIs are important to understand processes of CAI formation including the role of volatilization, condensation, and fractional crystallization [1,2]. REE measurements are a well established application of ion microprobes [e.g., 3]. However the spatial resolution of REE measurements by ion microprobe (approx.20 m) is not adequate to resolve heterogeneous distributions of REEs among/within minerals. We have developed methods for measuring REE with the NanoSIMS 50L at smaller spatial scales. Here we present our initial measurements of REEs in melilite and fassaite in an Allende Type-A CAI with the JSC NanoSIMS 50L. We found that the key parameters for accurate REE abundance measurements differ between the NanoSIMS and conventional SIMS, in particular the oxide-to-element ratios, the relative sensitivity factors, the energy distributions, and requisite energy offset. Our REE abundance measurements of the 100 ppm REE diopside glass standards yielded good reproducibility and accuracy, 0.5-2.5 % and 5-25 %, respectively. We determined abundances and spatial distributions of REEs in core and rim within single crystals of fassaite, and adjacent melilite with 5-10 m spatial resolution. The REE abundances in fassaite core and rim are 20-100 times CI abundance but show a large negative Eu anomaly, exhibiting a well-defined Group III pattern. This is consistent with previous work [4]. On the other hand, adjacent melilite shows modified Group II pattern with no strong depletions of Eu and Yb, and no Tm positive anomaly. REE abundances (2-10 x CI) were lower than that of fassaite. These patterns suggest that fassaite crystallized first followed by a crystallization of melilite from the residual melt. In future work, we will carry out a correlated study of O and Mg isotopes and REEs of the CAI in order to better understand the nature and timescales of its formation process and subsequent metamorphic history.

REE controls in ultramafic hosted MOR hydrothermal systems: An experimental study at elevated temperature and pressure

NASA Astrophysics Data System (ADS)

Allen, Douglas E.; Seyfried, W. E.

2005-02-01

A hydrothermal experiment involving peridotite and a coexisting aqueous fluid was conducted to assess the role of dissolved Cl - and redox on REE mobility at 400°C, 500 bars. Data show that the onset of reducing conditions enhances the stability of soluble Eu +2 species. Moreover, Eu +2 forms strong aqueous complexes with dissolved Cl - at virtually all redox conditions. Thus, high Cl - concentrations and reducing conditions can combine to reinforce Eu mobility. Except for La, trivalent REE are not greatly affected by fluid speciation under the chemical and physical condition considered, suggesting control by secondary mineral-fluid partitioning. LREE enrichment and positive Eu anomalies observed in fluids from the experiment are remarkably similar to patterns of REE mobility in vent fluids issuing from basalt- and peridotite-hosted hydrothermal systems. This suggests that the chondrite normalized REE patterns are influenced greatly by fluid speciation effects and secondary mineral formation processes. Accordingly, caution must be exercised when using REE in hydrothermal vent fluids to infer REE sources in subseafloor reaction zones from which the fluids are derived. Although vent fluid patterns having LREE enrichment and positive Eu anomalies are typically interpreted to suggest plagioclase recrystallization reactions, this need not always be the case.

Tectonic Origin of Serpentinites on Syros, Greece: Geochemical Signatures of Seafloor Serpentinization Preserved in the HP/LT Subduction Complex

NASA Astrophysics Data System (ADS)

Raia, N. H.; Cooperdock, E. H. G.; Barnes, J.; Stockli, D. F.; Schwarzenbach, E. M.

2016-12-01

Serpentinized ultramafic rocks are commonly found in exhumed HP/LT subduction complexes, but their tectonic origins (i.e., setting of serpentinization) are difficult to decipher due to extensive alteration. Growing literature and geochemical datasets demonstrate that immobile elements (REE, HFSE) in serpentinites can retain magmatic signatures indicative of the tectonic setting of parent peridotite, while fluid-mobile elements and stable isotopic signatures shed light on the fluids causing serpentinization. This study combines whole-rock trace and major element geochemistry, stable isotope (δD and δO) analyses with petrographic observation to determine the tectonic origin of ultramafic rocks in the HP/LT Aegean subduction complex. The best-preserved HP rocks of the Cycladic Blueschist Unit (CBU) are found on Syros, Greece, where serpentinized ultramafic rocks within the CBU are closely associated with metamorphosed remnants of subducted oceanic crust. All samples are completely serpentinized, lacking relict pyroxene or spinel grains, with typical assemblages consisting of serpentine, talc, chlorite, magnetite, and minor carbonate. The serpentinizing fluid was characterized using stable isotopes. δD and δO values of bulk-rock serpentinite powders and chips, respectively, suggest seafloor serpentinites hydrated by seawater at low T, typical of alteration at mid-ocean ridges and hyper-extended margins (δD = -64 to -33‰ and δO = 5.2 to 9.0‰). To fingerprint a tectonic origin, whole rock serpentinite REE patterns are compared to a global database of whole rock serpentinite analyses from fore-arc mantle wedge, mid-ocean ridge, and hyper-extended margin tectonic settings. Whole rock major element, trace element, and REE analyses are consistent with limited melt extraction, flat REE patterns (LaN/SmN = 0.2-2.6, SmN/YbN = 0.3-3.5; N= C1 normalized), and do not show pronounced Eu anomalies. These data are consistent with abyssal peridotites derived from hyper-extended margin settings, although some overlap with mid-ocean ridge serpentinites makes it difficult to rule out. In any case, the geochemical signatures retained in these serpentinites indicate they are unlikely sourced from the mantle wedge, as has been historically speculated.

Leaching of rare earth elements from fluorescent powder using the tea fungus Kombucha.

PubMed

Hopfe, Stefanie; Flemming, Katrin; Lehmann, Falk; Möckel, Robert; Kutschke, Sabine; Pollmann, Katrin

2017-04-01

In most modern technologies such as flat screens, highly effective magnets and lasers, as well as luminescence phosphors, Rare Earth Elements (REE) are used. Unfortunately no environmentally friendly recycling process exists so far. In comparison to other elements the interaction of microorganisms with REE has been studied to a less extent. However, as REE are ubiquitously present in nature it can be assumed that microorganisms play an important role in the biogeochemistry of REE. This study investigates the potential of organic acid-producing microbes for extracting REE from industrial waste. In Germany, 175 tons of fluorescent phosphor (FP) are collected per year as a distinct fraction from the recycling of compact fluorescent lamps. Because the FP contains about 10% of REE-oxides bound in the so-called triband dyes it is a readily accessible secondary resource of REE. Using the symbiotic mixed culture Kombucha, consisting of yeasts and acetic acid bacteria, REE were leached at a significant rate. The highest leaching-rates were observed in shake cultures using the entire Kombucha-consortium or its supernatant as leaching agent compared to experiments using the isolates Zygosaccharomyces lentus and Komagataeibacter hansenii as leaching organisms. During the cultivation, the pH decreased as a result of organic acid production (mainly acetic and gluconic acid). Thus, the underlying mechanism of the triband dye solubilisation is probably linked to the carboxyl-functionality or a proton excess. In accordance with the higher solubility of REE-oxides compared to REE-phosphates and -aluminates, the red dye Y 2 O 3 :Eu 2+ containing relatively expensive REE was shown to be preferentially solubilized. These results show that it is possible to dissolve the REE-compounds of FP with the help of microbial processes. Moreover, they provide the basis for the development of an eco-friendly alternative to the currently applied methods that use strong inorganic acids or toxic chemicals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rare earth elements in Hamersley BIF minerals

NASA Astrophysics Data System (ADS)

Alibert, Chantal

2016-07-01

Minerals from the Hamersley banded iron formation, Western Australia, were analyzed for Y and rare earth elements (YREEs) by laser ablation ICP-MS to investigate diagenetic pathways, from precursor phases to BIF minerals. One group of apatites carries the seawater REE signature, giving evidence that P and REEs, thoroughly scavenged from the water column by Si-ferrihydrite particles, were released upon microbial Fe3+ reductive dissolution of Si-ferrihydrite in pore-water and finally sequestered mainly in authigenic apatite. The absence of fractionation between apatite and seawater suggests that REE were first incorporated into an amorphous calcium phosphate as fully hydrated cations, i.e. as outer-sphere complexes. The iron oxides and carbonates carry only a small fraction of the whole-rock REE budget. Their REE patterns are distinctly enriched in Yb and show some M-type tetrad effect consistent with experimental Kd(REE) between solid and saline solution with low carbonate ion concentrations. It is deduced that hematite formed at an incipient stage of Fe2+-catalyzed dissolution of Si-ferrihydrite, via a dissolution-reprecipitation pathway. The REE pattern of greenalite, found as sub-micron particles in quartz in a chert-siderite sample, is consistent with its authigenic origin by precipitation in pore-water after dissolution of a small amount of Si-ferrihydrite. Magnetite carries very low YREEs (ppb-level), has an homogeneous pattern distinctly enriched in the mid-REEs compared to hematite, and includes a late population depleted in light-REEs, Ba and As. Magnetite forming aggregates and massive laminae is tentatively interpreted as reflecting some fluid-aided hematite-magnetite re-equilibration or transformation at low-grade metamorphic temperatures.

Rare earth elements geochemistry in springs from Taftan geothermal area SE Iran

NASA Astrophysics Data System (ADS)

Shakeri, Ata; Ghoreyshinia, Sayedkazem; Mehrabi, Behzad; Delavari, Morteza

2015-10-01

Concentrations of rare earth elements (REEs) were determined in springs and andesitic-dacitic rocks of Taftan geothermal field. Hydrochemical results of major ions indicate that thermal springs are Na-SO4-Cl and Ca-SO4-Cl types. Concentrations of REEs are in ranges of 10- 4 to 1.2 and 49 to 62 times of chondrite for springwater and rock samples, respectively. The thermal (STS and TTS) and the cold (APS) springs with low pH values exhibit a very high REE contents (0.64 to 3.15 mg/l). Saturation index indicates that Fe and Al phases can control dissolved REE concentration in FTS and PF cold springs. The speciation of REE complexes indicates dominant presence of LnSO4+ and free ion in the Taftan thermal springs. In APS cold spring with pH 4, fluoride complexes are dominate over the free ion and sulfate species, while in PF and FTS cold springs with pH 6.4 and 7, respectively, carbonate complexes (LnCO3+) are predominant species. Chondrite-normalized pattern for the low-pH waters show very distinctive gull-wing patterns, characteristic feature of acid-sulfate geothermal systems, and are similar to those of the host rocks. Chemical characteristics of rare earth elements in spring and volcanic rock samples indicate that REEs are originated from the andesitic-dacitic host rocks. Whole-rock-normalized REE patterns and petrographic evidences show that rare earth elements leached mainly from marginal alteration of minerals and matrix decomposition in volcanic rocks. In chondrite-normalized REE patterns, significant negative Eu anomaly in the cold springs compare to the thermal and acidic springs indicates that alteration of plagioclase is more intense in the later, corresponding to increasing in temperature and acidic state of reactant water.

Rare earth element metasomatism in hydrothermal systems: The Willsboro-Lewis wollastonite ores, New York, USA

USGS Publications Warehouse

Whitney, P.R.; Olmsted, J.F.

1998-01-01

Wollastonite ores and garnet-pyroxene skarns in the Willsboro-Lewis district, New York, USA were formed in a complex hydrothermal system associated with the emplacement of a large anorthosite pluton. Contact-metamorphic marbles were replaced by wollastonite, garnet, and clinopyroxene during infiltration metasomatism involving large volumes of water of chiefly meteoric origin. Rare earth elements (REE) in these rocks show large departures from the protolith REE distribution, indicative of substantial REE mobility. Three types of chondrite-normalized REE distribution patterns are present. The most common, found in ores and skarns containing andradite-rich garnet, is convex-up in the light REE (LREE) with a maximum at Pr and a positive Eu anomaly. Europium anomalies and Pr/Yb ratios are correlated with X(Ad) in garnet. This pattern (type C) results from uptake of REE from hydrothermal fluids by growing crystals of calcsilicate minerals, principally andradite, with amounts of LREE controlled by the difference in ionic radius between Ca++ and REE3+ in garnet X sites. The Eu anomaly results either from prior interaction of the fluids with plagioclase-rich, Eu-positive anorthositic rocks in and near the ore zone, or by enrichment of divalent Eu on growth surfaces of garnet followed by entrapment, or both. Relative enrichment in heavy REE (type H) occurs in ores and skarn where calcsilicates, including grossularitic garnet, in contact-metamorphic marble have been concentrated by dissolution of calcite. In most cases a negative Eu anomaly is inherited from the marble protolith. Skarns containing titanite and apatite exhibit high total REE, relative light REE enrichment, and negative Eu anomalies (type L). These appear to be intrusive igneous rocks (ferrodiorites or anorthositic gabbros) that have been converted to skarn by Ca metasomatism. REE, sequestered in titanite, apatite, and garnet, preserve the approximate REE distribution pattern of the igneous protolith. Post-ore granulite facies metamorphism homogenized zoned mineral grains without causing complete intergranular reequilibration and does not appear to have significantly affected the whole-rock REE distributions. These results demonstrate that extensive REE metasomatism can occur in hydrothermal systems at shallow to intermediate depths and that REE geochemistry may be useful in discerning the origin of skarns and skarn-related ore deposits.

Weathering behavior of REE-Y in a granitic soil profile (Case of Strengbach watershed)

NASA Astrophysics Data System (ADS)

Gangloff, Sophie; Stille, Peter; Chabaux, François

2017-04-01

Rare earth elements and yttrium (REE-Y) can be used as tracers of bedrock weathering and soil formation. One of the aims of this study is to better understand the different phenomena which impact the REE-Y mobilization and modify the REE-Y pattern along a soil profile. Our study has been performed on a granitic soil profile and soil solutions corresponding, sampled in a forest parcel covered with spruces from the Strengbach catchment. The behavior of the REE-Y pattern are compared with previously published results. The samples were collected from 2009 to 2013 and ultra-filtered to determine the spatial and temporal influence as well as that of the colloidal and dissolved fractions on the evolution of the REE-Y patterns. The EFTi of the soil indicates that during alteration process, phosphate minerals and zircon might be dissolved and induce the formation of secondary mineral phase like xenotime in the deeper soil horizons. The ultra-filtered soil solutions from humic horizon show that the REE-Y are principally enriched in the colloidal fraction controlling the REE-Y dynamic while in the deeper soil solutions colloidal and dissolved fractions influence the REE-Y. The mobility of REE-Y is controlled by the dissolution of the zircon and phosphate minerals, the precipitation of the REE-Y(PO4) and the evolution of OC with depth. The comparative study of the soil profile, soil water extracts and soil solutions show that (Eu*/Eu)DS anomaly reflects weathering of plagioclase in the micropores and the migration of the released Eu to the macropores, the (Ce*/Ce) anomaly, is stabilized by the electron shuttling of the humic acid (aromaticity) and provides information on the redox conditions only in the deeper soil horizons depleted in humic acid and finally the HREE enrichment in the deeper soil solutions results from the partial dissolution of secondary minerals in the upper soil horizons (above 30 cm depth).

Geochemistry of pillow lavas and sheeted dikes from Nain and Ashin ophiolites (Central Iran)

NASA Astrophysics Data System (ADS)

Saccani, Emilio; Pirnia Naeini, Tahmineh; Torabi, Ghodrat

2017-04-01

An extensive, worldwide database on the geochemistry of basalts from well-known tectonic settings is available. Knowing the chemistry of basalts on one hand, and the tectonic setting of their origin on the other hand, resulted in the development of tectonic discrimination diagrams. Recently developed discrimination diagrams allow us to determine the tectonic setting of volcanics with almost neglectable probability of misclassification (<1%). One major application of these diagrams lies in discriminating the tectonic setting of formation of ophiolites, particularly in poorly-known areas. A good example is the Inner ophiolite belt of Iran, located in Central Iran. The geodynamic significance of the inner ophiolites is still poorly known. From the Inner ophiolites, either no volcanic section is reported, or, the data are highly limited and poorly-reliable due the high degree of alteration of the studied samples. We have been able to overcome this problem by spotting relatively well-preserved outcrops of pillow lavas and sheeted dikes from two ophiolite mélanges of Central Iran, Nain and Ashin ophiolites. The two mélanges are located in the west of Central-East Iranian microplate. In total, 28 samples have been collected from the pillow lavas and sheeted dikes outcrops. The studied volcanic rocks consist mainly of basalts and minor ferrobasalts and basaltic andesites, all showing a clear subalkaline nature (e.g., Nb/Y = 0.03-0.21). Two samples from the Nain ophiolite are characterized by N-MORB normalized incompatible element patterns showing marked Th positive anomalies and Ta, Nb, Ti negative anomalies. Chondrite-normalized REE patterns show LREE/HREE (light REE/heavy REE) enrichment, with LaN/YbN=3.2-4.3. These rocks are chemically similar to the calc-alkaline basalts (CAB), as also highlighted by many discrimination diagrams. These rocks are interpreted to have generated in a cordilleran-type volcanic arc setting. All other samples from both the Nain and Ashin ophiolites display a wide range of chemical composition. However, the relatively less fractionated basalts are characterized by low TiO2 (0.60-1 wt%), P2O5 (0.03-0.08 wt%), Zr (23-75 ppm) and Y (9-27) contents. Cr (38-619 ppm) and Ni (22-220 ppm) contents show a wide range of variation. N-MORB normalized incompatible element patterns show rather flat trends and a general depletion (from 0.4 to 0.8 times N-MORB composition) coupled with a slight Th enrichment (1-3 times N-MORB). Chondrite-normalized REE patterns are generally flat and are characterized by either a slight depletion or a slight enrichment in LREE compared to HREE (LaN/YbN=0.7-1.2). These overall chemical features resemble those of island arc tholeiites from many ophiolitic complexes. The depletion in incompatible elements compared to N-MORB suggest that these rocks were derived from partial melting of a depleted mantle source. Th enrichment with respect to Nb (ThN/NbN = 2.6-12.4) suggests that mantle sources underwent enrichment in subduction-derived chemical components prior melting. Our data suggest that the Nain and Ashin ophiolites were formed in a subduction-related tectonic setting during the Late Cretaceous. The chemistry of the studied rocks is compatible with transition zone either from forearc to arc or from arc to backarc.

Proterozoic Eastern Sayan ophiolites (Central Asian Orogenic Belt) record subduction initiation in vicinity of continental block

NASA Astrophysics Data System (ADS)

Belyaev, Vasilii; Gornova, Marina; Medvedev, Alexander; Dril, Sergey; Karimov, Anas

2017-04-01

Geochemical study of cumulate and volcanic rocks from ˜ 1020 Ma Eastern Sayan ophiolites1 (Siberia, Russia) is used to provide a correlation between two ophiolitic belts and link them to subduction initiation setting. Studied areas include Ospin and Ilchir massifs to the East and Dunzhugur to the West of Early Precambrian Gargan block. Ophiolitic cumulates represent peridotite-pyroxenite-gabbro-norite suite with crystallization orders of Cr-Sp - Ol - Cpx - Opx - Plag, and Cr-Sp - Ol - Opx - Amph - (Cpx) - Plag. Clinopyroxene is augite-diopside with Mg# 85-95, low Al2O3 (1-2.5%) and TiO2 (0.05-0.2%). Amph is Mg-hornblende to edenite (Mg# 84-86, 5-8% Al2O3, 0.3-0.6% TiO2). Cr-Sp has Cr# 65-83 and 0.05-0.3% TiO2 in cumulates with high Opx proportion, while in Cpx-dominating pyroxenites chemistry of Cr-Sp is variable (Cr# 40-75, 0.05-0.5% TiO2). Due to alteration, Ol and Opx chemistry is available only for some samples (Ol: Mg# 88, 0.2-0.3% NiO; Opx: Mg# 89, 1.6% Al2O3). Whole-rock MgO ranges 9 to 38%. Amph-free pyroxenites and gabbro-norites show flat to slightly depleted REE pattern with negative HFSE anomalies. Amph-pyroxenites have fractionated trace-element pattern with LREE enrichment, Nb-Ti minima at slightly higher HFSE abundances. In-situ LA-ICP-MS analysis of Cpx in Amph-free pyroxenites and gabbro-norites revealed moderately depleted to flat REE and Nb-Zr-Hf-Ti depletion, with low trace element abundances (La/SmPM = 0.14-0.9, Zr 0.6-2.3, Nd = 0.2-1.1, Yb = 0.2-0.7 ppm). Melts calculated to be in equilibrium with Cpx using distribution coefficients2 are REE-flat to slightly LREE-enriched (La/SmPM = 1-4) at low HREE abundances (0.5-1.5 ppm Yb). Overall, crystallization orders, mineral and whole-rock chemistry suggest origin of ophiolitic cumulates from low-Ca boninites or primitive andesites (higher Opx or Amph proportion) to high-Ca boninites or primitive island arc tholeiites (Cpx-dominating, Amph-free associations with subordinate Opx). Ophiolitic volcanics and dikes are low-Ca and intermediate-Ca boninites, andesite-basalts, andesites, dacites of calc-alkaline (CA) affinity with rare evolved island-arc tholeiitic (IAT) andesite-basalts. They resemble appropriate rocks of intraoceanic island arcs, forearcs, and ophiolites. Boninites and CA-andesites are LREE-enriched (La/SmPM 1.2-3.8) at low HREE (0.5-1.6 ppm Yb) contents while evolved IAT show flat REE (La/SmPM = 1.1) and higher abundances (2.4-2.8 ppm Yb), and both have negative Nb anomalies. Nd-isotopic data expressed as epsilon Nd(1020Ma) values are -2.3 to +4.1 in cumulates, -2.8 to +0.4 in boninites and andesites, and +2.3 to +2.7 in IAT (compared to epsilon Nd(1020Ma) +7.8 in depleted mantle). The ophiolites obducted on the Gargan continental block, which contains Archean gneisses with epsilon Nd(1020) = -20 to -281. Subduction and recycling of sediments derived from these gneisses could explain enriched Nd isotopic characteristics of the studied ophiolitic rocks. The boninite-andesite-IAT association is usually found in subduction initiation settings recorded by modern forearc regions and forearc ophiolites. The difference of the Eastern Sayan ophiolites is their supposed formation close to ancient continental block which supplied recycled material into newly formed subduction zone. 1. Sklyarov et al (2016) Russ Geol Geophys 57, 127-140 2. Sobolev et al (1996) Petrology 3, 326-336.

Genesis of iron-apatite ores in Posht-e-Badam Block (Central Iran) using REE geochemistry

NASA Astrophysics Data System (ADS)

Mokhtari, Mir Ali Asghar; Zadeh, Ghader Hossein; Emami, Mohamad Hashem

2013-06-01

Rare earth elements in apatites of different ore types show characteristic patterns which are related to different modes of formation of the ores. Most of the apatite-bearing iron ores are associated with alkaline magmas with LREE/HREE fractionation varying from moderate to steep. Iron-apatite deposits in Posht-e-Badam Block (Central Iran) have a high concentration of REE (more than 1000 ppm up to 2.5%), and show a strong LREE/HREE ratio with a pronounced negative Eu anomaly. This REE pattern is typical of magmatic apatite and quiet distinct from sedimentary apatites (phosphorites) which have a low REE contents and Ce negative anomalies. On the other hand, they are comparable to the REE patterns of apatites in Kiruna-type iron ores in different parts of the world. The REE patterns of apatites, iron-apatite ores and iron ores are similar and only have different REE contents. This similarity indicates a genetic relation for these rocks. Most of the iron-apatite deposits in Central Iran have similar REE patterns too, which in turn show a genetic relation for all of these deposits. This similarity indicates a similar origin and processes in their genesis. There are some small intrusions around some of the iron-apatite deposits that are petrographically identified as syenite and gabbro. These intrusions also have REE patterns similar to that of iron-apatite ores. This demonstrates a genetic relation between these intrusions and iron-apatite ores. The REE patterns of apatites in different deposits of Posht-e-Badam Block iron-apatite ores show an affinity to alkaline to sub-alkaline magmas and rifting environment. The alkaline host rocks of Central Iran iron-apatite ores are clearly related to an extensional setting where rifting was important (SSE-NNW fault lines). A probable source for this large scale ore forming processes is relatively low partial melting of mantle rocks. The ores have originated by magmatic differentiation as a late phase in the volcanic cycle forming sub-surface injections or surface flows. These ores have formed during magmatism as immiscible liquids (silicate and Fe-P-rich magmatic liquids) which separated from strongly differentiated magmas aided by a large volatile and alkali element content. Separation of an iron oxide melt and the ensuing hydrothermal processes dominated by alkali metasomatism were both involved to different degrees in the formation of Posht-e-Badam Block iron-apatite deposits. We proposed that the separation of an iron oxide melt and the ensuing hydrothermal processes dominated by alkali metasomatism were both involved to different degrees in the formation of Posht-e-Badam Block iron-apatite deposits.

Rare earth elements in apatite: Uptake from H{sub 2}O-bearing phosphate-fluoride melts and the role of volatile components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fleet, M.E.; Pan, Yuanming

The partitioning of rare earth elements (REEs) between fluorapatite (FAp) and H{sub 2}O- bearing phosphate-fluoride melts has been studied at about 700 and 800{degrees}C and 0.10-0.15 GPa. REE uptake patterns, i.e., plots of D(REE:FAp/melt), are convex upwards and peak near Nd for single-REE substituted FAp at minor (0.03-0.25 wt% REE{sub 2}O{sub 3}) abundances, and binary (LREE + HREE)-substituted FAp, and hexa-REE-substituted FAp at minor to major (0.25-7.8 wt% REE{sub 2}O{sub 3}) abundances. Partition coefficients for minor abundances of REE and depolymerized phosphate melts are about 5, 8, and 1 for La, Nd, and Lu, respectively and broadly comparable to thosemore » for early fluorapatite in the fractionation of melts of basaltic composition. The Ca2 site exerts marked control on the selectivity of apatite for REE because it preferentially incorporates LREE and its effective size varies with substitution of the A-site volatile anion component (F, Cl, OH). Using simple crystal-chemical arguments, melt(or fluid)-normalized REE patterns are predicted to peak near Nd for fluorapatite and be more LREE-enriched for chlorapatite. These predictions are consistent with data from natural rocks and laboratory experiments. The wide variation in D(REE:apatite/melt) in nature (from <1 for whitlockite-bearing lunar rocks to about 100 for evolved alkalic rocks) is attributed largely to the influence of the volatile components. 49 refs., 8 figs., 3 tabs.« less

Distribution characteristics of rare earth elements in children's scalp hair from a rare earths mining area in southern China.

PubMed

Tong, Shi-Lu; Zhu, Wang-Zhao; Gao, Zhao-Hua; Meng, Yu-Xiu; Peng, Rui-Ling; Lu, Guo-Cheng

2004-01-01

In order to demonstrate the validity of using scalp hair rare earth elements (REEs) content as a biomarker of human REEs exposure, data were collected on REEs exposure levels from children aged 11-15 years old and living in an ion-adsorptive type light REEs (LREEs) mining and surrounding areas in southern China. Sixty scalp hair samples were analyzed by ICP-MS for 16 REEs (La Lu, Y and Sc). Sixteen REEs contents in the samples from the mining area (e.g., range: La: 0.14-6.93 microg/g; Nd: 0.09-5.27 microg/g; Gd: 12.2-645.6ng/g; Lu: 0.2-13.3 ng/g; Y: 0.03-1.27 microg/g; Sc: 0.05-0.30 microg/g) were significantly higher than those from the reference area (range: La: 0.04-0.40 microg/g; Nd: 0.04-0.32 microg/g; Gd: 8.3-64.6 ng/g; Lu: 0.4-3.3ng/g; Y: 0.03-0.29 microg/g; Sc: 0.11-0.36 microg/g) and even much higher than those published in the literature. The distribution pattern of REEs in scalp hair from the mining area was very similar to that of REEs in the mine and the atmosphere shrouding that area. In conclusion, the scalp hair REEs contents may indicate not only quantitatively but also qualitatively (distribution pattern) the absorption of REEs from environmental exposure into human body. The children living in this mining area should be regarded as a high-risk group with REEs (especially LREEs) exposure, and their health status should be examined from a REEs health risk assessment perspective.

Complementary rare earth element patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the earth

NASA Technical Reports Server (NTRS)

Ma, M.-S.; Schmitt, R. A.; Laul, J. C.

1982-01-01

Abundances of major, minor, and trace elements are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare earth element (REE) abundances of ALHA 77005 reveal a unique chondritic normalized pattern; that is, the REEs are nearly unfractionated from La to Pr at approximately 1.0X chondrites, monotonically increased from Pr to Gd at approximately 3.4X with no Eu anomaly, nearly unfractionated from Gd and Ho and monotonically decreased from Ho to Lu at approximately 2.2X. It is noted that this unique REE pattern of ALHA 77005 can be modeled by a melting process involving a continuous melting and progressive partial removal of melt from a light REE enriched source material. In a model of this type, ALHA 77005 could represent either a crystallized cumulate from such a melt or the residual source material. Calculations show that the parent liquids for the shergottites could also be derived from a light REE enriched source material similar to that for ALHA 77005.

High contents of rare earth elements (REEs) in stream waters of a Cu-Pb-Zn mining area.

PubMed

Protano, G; Riccobono, F

2002-01-01

Stream waters draining an old mining area present very high rare earth element (REE) contents, reaching 928 microg/l as the maximum total value (sigmaREE). The middle rare earth elements (MREEs) are usually enriched with respect to both the light (LREEs) and heavy (HREEs) elements of this group, producing a characteristic "roof-shaped" pattern of the shale Post-Archean Australian Shales-normalized concentrations. At the Fenice Capanne Mine (FCM), the most important base metal mine of the study area, the REE source coincides with the mine tailings, mostly the oldest ones composed of iron-rich materials. The geochemical history of the REEs released into Noni stream from wastes in the FCM area is strictly determined by the pH, which controls the REE speciation and in-stream processes. The formation of Al-rich and mainly Fe-rich flocs effectively scavenges the REEs, which are readily and drastically removed from the solution when the pH approaches neutrality. Leaching experiments performed on flocs and waste materials demonstrate that Fe-oxides/oxyhydroxides play a key role in the release of lanthanide elements into stream waters. The origin of the "roof-shaped" REE distribution pattern as well as the peculiar geochemical behavior of some lanthanide elements in the aqueous system are discussed.

Trace elements and REE geochemistry of Middle Devonian carbonate mounds (Maïder Basin, Eastern Anti-Atlas, Morocco): Implications for early diagenetic processes

NASA Astrophysics Data System (ADS)

Franchi, Fulvio; Turetta, Clara; Cavalazzi, Barbara; Corami, Fabiana; Barbieri, Roberto

2016-08-01

Trace and rare earth elements (REEs) have proven their utility as tools for assessing the genesis and early diagenesis of widespread geological bodies such as carbonate mounds, whose genetic processes are not yet fully understood. Carbonates from the Middle Devonian conical mud mounds of the Maïder Basin (eastern Anti-Atlas, Morocco) have been analysed for their REE and trace element distribution. Collectively, the carbonates from the Maïder Basin mud mounds appear to display coherent REE patterns. Three different geochemical patterns, possibly related with three different diagenetic events, include: i) dyke fills with a normal marine REE pattern probably precipitated in equilibrium with seawater, ii) mound micrite with a particular enrichment of overall REE contents and variable Ce anomaly probably related to variation of pH, increase of alkalinity or dissolution/remineralization of organic matter during early diagenesis, and iii) haematite-rich vein fills precipitated from venting fluids of probable hydrothermal origin. Our results reinforce the hypothesis that these mounds were probably affected by an early diagenesis induced by microbial activity and triggered by abundance of dispersed organic matter, whilst venting may have affected the mounds during a later diagenetic phase.

Dating high-grade metamorphism: constraints from zircon and garnet REE compositions

NASA Astrophysics Data System (ADS)

Whitehouse, M. J.; Platt, J. P.

2001-12-01

We present high spatial resolution ion microprobe REE analyses of zircon and garnet from pelitic granulite adjacent to the Ronda peridotite, Betic Cordillera, southern Spain. The zircons exhibit polyphase growth, with thick structureless (in cathodoluminescence) overgrowths over detrital cores. These overgrowths yield a U-Pb age of 21.3 +/- 0.3 Ma [1, unpublished data] which we intepret as dating an episode of zircon growth during the Alpine orogeny. REE analyses of the dated portions of these zircons reveal profound differences between cores and rims. Cores show patterns typical of magmatic zircon (steep upward slopes from La to Lu with marked positive Ce anomaly), while the overgrowths are characterised by flat or even negatively sloping HREE profiles (Gd - Lu). Garnet, which occupies ca. 30 % by volume of the rock, is the most likely phase to host the HREEs in the rock and has been the subject of further ion-microprobe REE, textural and trace element investigations. The garnets are themselves zoned, with dominant central regions that are relatively free of inclusions overgrown by inclusion-rich, more calcic rims. Inclusions of kyanite +rutile in the central regions and sillimanite +ilmenite in the rims suggests that the garnets grew during decompression, and the Ca-enrichment in the rims suggests that their growth coincided with the initiation of partial melting. The presence of rimmed zircons only in the garnet rims and the matrix further suggests that the zircons also grew during this late decompressional history. An REE traverse of the garnet from core to rim reveals marked HREE depletion in the rims relative to the cores which we suggest is consistent with the textural evidence and probably results from early garnet core growth strongly depleting the HREEs available to subsequent growth. This mechanism can also be invoked to explain depletion in the zircon rims and more closely ties their formation to this stage of garnet growth. We therefore interpret the 21.3 +/- 0.3 Ma U-Pb age from the zircon rims as dating a point on the decompressional path rather than peak metamorphic pressure. [1] Platt, J.P. and Whitehouse, M.J. (1999) EPSL 171, 591-605.

Isotope U-Pb age on single zircon and REE distribution in rocks and zircon from paleoproterozoic Kandalaksha-Kolvitsa complex Baltic shield

NASA Astrophysics Data System (ADS)

Steshenko, Ekaterina; Bayanova, Tamara; Drogobuzhskaya, Svetlana; Lyalina, Ludmila; Serov, Pavel; Chashchin, Viktor; Elizarov, Dmitriy

2017-04-01

Kandalaksha-Kolvitsa paleoproterozoic complex located in the N-E part of Baltic shield and consists of three zones. Marginal zone (mesocratic metanorite) lies at the base of the massif. Main zone is composed of leucocratic metagabbro. The upper zone is alteration of mataanorthosite and leucocratic metagabbro. All rocks were subjected to granulate and anorthositic metamorphism. Age of magmatic crystallization of the massif was determined for the first time, using the U-Pb isotope method for single zircon grains. Three fractions of single zircons from anorthosite of the Kandalaksha massif gave precise U-Pb age of 2435.5 ± 4.8 Ma. For the first time REE concentration (WR) was determined using a quadrupole mass spectrometer (Agilent 7500 ce ICP-MS) in the main varieties of rocks of the Kandalaksha-Kolvitsa paleoproterozoic complex. Anorthosite and leucocratic metagabbros (main zone) are characterized by a flat spectrum distribution of HREE, which were normalized by [1]. The REE pattern is characterized by significant positive anomalies of Eu ((Eu / Eu *)n = 3.72-3.91) in anorthosite and leucogabbros and 7.26 - in ortoamfibolitah. General content of individual elements that are common for this type of rocks: Cen = 5.82-8.54, Ybn = 1.54-1.58, which indicates that the process of crystallization of the rock occurred with predominant accumulation of plagioclase. According to geochemical and Nd-Sr isotopic data (ISr=0.702 - 0.706, ɛNd(T) = +1 - (-3)) Kandalaksha Kolvitsa complex, appear to have a general plume source with Paleoproterozoic layered intrusions of the Baltic Shield [2] Distribution of REE (ELAN-9000 ICP-MS) in zircon have a typical magmatic species: a positive Ce, negative Eu anomaly and HREE flat spectrum. Titanium content in zircons were measured for the calculation of their crystallization temperature with 8350C. These data are evidence of magmatic origin of zircon [3]. The scientific researches are supported by RFBR (projects № 15-35-20501, № 16-05-00305, 16-05-00367, 16-05-00427) and theme of state assignment № 0231-2015-0005. References: 1. Boynton W.V. Cosmochemistry of the rare earth elements: meteorite studies // Ed. Henderson P. Rare earth element geochemistry. Amsterdam: Elsevier. 1984. P. 63-114. 2. Watson E. B., Wark D.A., Thomas J.B. Crystallization thermometers for zircon and rutile // Contrib. Miner. Petrol. 2006. V. 151. P. 413-433. 3. Hoskin P.W.O. and Schaltegger U. The Composition of zirconand igneous and metamorphic petrogenesis // Reviews in mineralogy & geochemistry. 2003. V. 53. P. 27-62.

Source and path identification of metals pollution in a mining area by PMF and rare earth element patterns in road dust.

PubMed

Tian, Shuhan; Liang, Tao; Li, Kexin; Wang, Lingqing

2018-08-15

To better assess pollution and offer efficient protection for local residents, it is necessary to both conduct an exhaustive investigation into pollution levels and quantify its contributing sources and paths. As it is the biggest light rare earth element (REE) reserve in the world, Bayan Obo deposit releases large amounts of heavy metals into the surrounding environment. In this study, road dust from zones located at different distances to the mining area was collected and sieved using seven sizes. This allowed for subsequent analysis of size-dependent influences of mining activities. A receptor model was used to quantitatively assess mine contributions. REE distribution patterns and other REE parameters were compared with those in airborne particulates and the surrounding soil to analyze pollution paths. Results showed that 27 metals were rated as moderately to extremely polluted (2

Geochemical, oxygen, and neodymium isotope compositions of metasediments from the Abitibi greenstone belt and Pontiac Subprovince, Canada: Evidence for ancient crust and Archean terrane juxtaposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, R.; Kerrich, R.; Maas, R.

1993-02-01

The Abitibi greenstone belt (AGB) and Pontiac Subprovince (PS) in the southwestern Superior Province are adjacent greenstone-plutonic and metasedimentary-dominated terranes, respectively, separated by a major fault zone. Metasediments from these two contrasting terranes are compared in terms of major- and trace-element and O- and Nd-isotope compositions, and detrital zircon ages. The following two compositional populations of metasediments are present in the low-grade, Abitibi southern volcanic zone: (1) a mafic-element-enriched population (MEP) characterized by flat, depleted REE patterns; enhanced Mg, Cr, Co, Ni, and Sc; low-incompatible-element contents; and minor or absent normalized negative troughs at Nb, Ta, and Ti; and (2)more » a low-mafic-element population (LMEP) featuring LREE-enriched patterns; enhanced Rb, Cs, Ba, Th, and U contents; and pronounced normalized negative troughs at Nb, Ta, and Ti. These geochemical features are interpreted to indicate that the MEP sediments were derived from an ultramafic- and mafic-dominated oceanic provenance, whereas the LMEP sediments represent mixtures of mafic and felsic are source rocks. The PS metasediments are essentially indistinguishable from Abitibi LMEP on the basis of major-element and transition metal abundances, suggesting comparable types of source rocks and degrees of maturity, but are distinct in terms of some trace elements and O-isotope compositions. The Pontiac metasediments are depleted in [sup 18]O and enriched in Cs, Ba, Pb, Th, U, Nb, Ta, Hf, Zr, and total REE and also have higher ratios of Rb/K, Cs/Rb, Ba/Rb, Ta/Nb, Th/La, and Ba/La relative to the Abitibi LMEP. Two subtypes of REE patterns have been identified in PS metasediments. The first subtype is interpreted to be derived from provenances of mixed mafic and felsic volcanic rocks, whereas the Eu-depleted type has features that are typical of post-Archean sediments or Archean K-rich granites and volcanic equivalents. 100 refs., 9 figs., 4 tabs.« less

Trace element mobility in dolomitic argillites of the Mesoproterozoic Belt-Purcell Supergroup, Western North America

NASA Astrophysics Data System (ADS)

González-Álvarez, Ignacio; Kerrich, Robert

2011-04-01

The Belt-Purcell Supergroup comprises dolomite-rich stratigraphic units in a dominantly siliciclastic succession, where sedimentation spans 1400-1470 Ma. Dolomitic units are variable mixtures of co-sedimented argillite and primary carbonate post-depositionally converted to secondary dolomite. Based on rare earth element (REE) relationships three distinct REE patterns are identified in the dolomite-rich units: Type 1 (T1d; d = dolomitic sample) with REE patterns parallel to post-Archean Upper Continental Crust (PA-UCC), albeit at lower absolute abundances due to dilution by carbonate content; Type 2 (T2d) with Heavy REE (HREE) enrichment but Light REE (LREE) depletion relative to T1d; and Type 3 (T3d) with enrichment in LREE and HREE relative to T1d, but erratic Middle REE (MREE) patterns. There is a progressive increase of ΣREE from T1d through T2d to T3d, whereas for ΣLREE/ΣHREE T2d < T1d < T3d. T1d-T2d and T3d represent three different "snapshots" of a continuous process. In terms of timing, dolomitization of calcite primary sediment in all samples likely took place broadly during burial diagenesis, as inferred for most Proterozoic dolomites. T1d is easily explained by provenance: however, T2d and T3d cannot be related to provenance, weathering or sedimentary sorting processes to explain higher concentrations of HREE referenced to PA-UCC and consequently developed in the sediment from a T1d precursor. The same three REE signatures have been described in previous studies in counterpart siliciclastic counterparts throughout the Belt-Purcell Supergroup at three different locations. Mobility of normally stable REE is accompanied by mobility of normally isochemical high field strength elements (HFSE) in T2d and T3d to give REE/REE, HFSE/HFSE, REE/HFSE and Y/HREE fractionations. No specific REE-HFSE signatures are apparent in the carbonate-rich units as compared to their non-dolomitic siliciclastic counterparts. This unusual mobility of REE and HFSE reflected in T2d and T3d is attributed to alkaline oxidizing post-depositional brines. Salinity was derived from seawater-sediment reactions, dissolution of evaporite minerals, and the smectite-illite transformation, whereas alkaline oxidizing conditions were promoted by groundwater interaction with mafic units in the basin, CO 2 introduced into the system during episodic rifting with mantle degassing, and interaction of syn-sedimentary mafic intrusions with carbonate units at early stages of BPS deposition. Intermittent brine activity, inducing T2d and T3d patterns, spanned >1 Ga as recorded by secondary monazite grains with age distributions that correspond to large scale tectono-thermal events in Laurentia. Post-depositional processes and redistribution of carbonate can have an impact on transitional stratigraphic contacts between dolomitic and siliciclastic units which may have been incorrectly described as primary due to sedimentary environment changes.

Rare earth elements in the phosphatic-enriched sediment of the Peru shelf

USGS Publications Warehouse

Piper, D.Z.; Baedecker, P.A.; Crock, J.G.; Burnett, W.C.; Loebner, B.J.

1988-01-01

Apatite-enriched materials from the Peru shelf have been analyzed for their major oxide and rare earth element (REE) concentrations. The samples consist of (1) the fine fraction of sediment, mostly clay material, (2) phosphatic pellets and fish debris, which are dispersed throughout the fine-grained sediment, (3) tabular-shaped phosphatic crusts, which occur within the uppermost few centimeters of sediment, and (4) phosphatic nodules, which occur on the seafloor. The bulk REE concentrations of the concretions suggest that these elements are partitioned between the enclosed detrital material and the apatite fraction. Analysis of the fine-grained sediment with which the samples are associated suggested that this detrital fraction in the concretions should have shale REE values; the analysis of the fish debris suggested that the apatite fraction might have seawater values. The seawater contribution of REE's is negligible in the nodules and crust, in which the apatite occurs as a fine-grained interstitial cement. That is, the concentration of REE's and the REE patterns are predominantly a function of the amount of enclosed fine-grained sediment. By contrast, the REE pattern of the pelletal apatite suggests a seawater source and the absolute REE concentrations are relatively high. The REE P2O5 ratios of the apatite fraction of these samples thus vary from approximately zero (in the case of the crust and nodules) to as much as approximately 1.2 ?? 10-3 (in the case of the pellets). The range of this ratio suggests that rather subtle variations in the depositional environment might cause a significant variation in the REE content of this authigenic fraction of the sediment. Pelletal glauconite was also recovered from one sediment core. Its REE concentrations closely resemble those of the fish debris. ?? 1988.

Geochemical characteristics of dissolved rare earth elements in acid mine drainage from abandoned high-As coal mining area, southwestern China.

PubMed

Li, Xuexian; Wu, Pan

2017-09-01

Acid mine drainage (AMD) represents a major source of water pollution in the small watershed of Xingren coalfield in southwestern Guizhou Province. A detailed geochemical study was performed to investigate the origin, distribution, and migration of REEs by determining the concentrations of REEs and major solutes in AMD samples, concentrations of REEs in coal, bedrocks, and sediment samples, and modeling REEs aqueous species. The results highlighted that all water samples collected in the mining area are identified as low pH, high concentrations of Fe, Al, SO 4 2- and distinctive As and REEs. The spatial distributions of REEs showed a peak in where it is nearby the location of discharging of AMD, and then decrease significantly with distance away from the mining areas. Lots of labile REEs have an origin of coal and bedrocks, whereas the acid produced by the oxidation of pyrite is a prerequisite to cause the dissolution of coal and bedrocks, and then promoting REEs release in AMD. The North American Shale Composite (NASC)-normalized REE patterns of coal and bedrocks are enriched in light REEs (LREEs) and middle REEs (MREEs) relative to heavy REEs (HREEs). Contrary to these solid samples, AMD samples showed slightly enrichment of MREEs compared with LREEs and HREEs. This behavior implied that REEs probably fractionate during acid leaching, dissolution of bedrocks, and subsequent transport, so that the MREEs is primarily enriched in AMD samples. Calculation of REEs inorganic species for AMD demonstrated that sulfate complexes (Ln(SO 4 ) + and Ln(SO 4 ) 2 - ) predominate in these species, accounting for most of proportions for the total REEs species. The high concentrations of dissolved SO 4 2- and low pH play a decisive role in controlling the presence of REEs in AMD, as these conditions are necessary for formation of stable REEs-sulfate complexes in current study. The migration and transportation of REEs in AMD are more likely constrained by adsorption and co-precipitation of Fe-Al hydroxides/hydroxysulfate. In addition, the MREEs is preferentially captured by poorly crystalline Fe-Al hydroxides/hydroxysulfate, which favors that sediments also preserve NASC-normalized patterns with MREEs enrichment in the stream.

Rare Earth Element Behavior During Incongruent Weathering and Varying Discharge Conditions in Silicate Dominated River Systems: The Australian Victorian Alps

NASA Astrophysics Data System (ADS)

Hagedorn, K. B.; Cartwright, I.

2008-12-01

The distribution of rare earth elements (REE) and trace elements was measured by ICP-MS on fresh, slightly weathered and weathered granite and surface water samples from a network of 11 pristine rivers draining the Australian Victorian Alps during (i) high and (ii) low discharge conditions. River water REE concentrations are largely derived from atmospheric precipitation (rain, snow), as indicated by similar Chondrite normalized REE patterns (higher LREE over HREE; negative Ce anomalies, positive Eu anomalies) and similar total REE concentrations during both dry and wet seasons. Calculations based on the covariance between REE and Cl concentrations and oxygen and hydrogen isotopes indicate precipitation input coupled with subsequent evaporation may account for 30% o 100% of dissolved REE in stream waters. The dissolved contribution to the granitic substratum to stream water comes mainly from the transformation of plagioclase to smectite, kaolinite and gibbsite and minor apatite dissolution. However, since most REE of the regional granite are present in accessory minerals (titanite, zircon, etc.) they do not significantly contribute to the river REE pool. REE concentrations drop sharply downstream as a result of dilution and chemical attenuation. A trend of downstream enrichment of the heavier REE is due to selective partitioning of the lighter REE (as both free REE or REECO3 complexes) to hydrous oxides of suspended Al which, in turn, is controlled by a downstream increase of pH to values > 6.1 (for free REE) and > 7.3 (for REECO3 complexes). Although most circumneutral waters were supersaturated with REE phosphate compounds, precipitation of LnPO4 is not believed to have been a dominant process because the predicted phosphate fractionation pattern is inconsistent with the observed trends. Negative saturation indices of hydrous ferric oxides also militate against surface complexation onto goethite. Instead, REE attenuation most likely resulted from adsorption onto hydrous aluminium oxide. Seasonally, higher total REE concentrations during the dry season are due to longer residence time of water within rock fractures as well as high rainfall REE concentrations which, for the summer of 2007, might be related to organic carbon rich dust released after bushfires in the region. Lower pH values and low oxidation potentials at that time also contribute to raise REE concentrations through desorption.

The potential of sedimentary foraminiferal rare earth element patterns to trace water masses in the past

NASA Astrophysics Data System (ADS)

Osborne, Anne H.; Hathorne, Ed C.; Schijf, Johan; Plancherel, Yves; Böning, Philipp; Frank, Martin

2017-04-01

Dissolved rare earth element (REE) concentration data from intermediate and deep seawater form an array characterized by higher middle-REE enrichments (MREE/MREE*) in the North Atlantic and a progressive increase in heavy-to-light REE ratios (HREE/LREE) as water masses age. The REEs in foraminifera are fractionated toward higher MREE/MREE* and lower HREE/LREE relative to seawater. Calculations based on a scavenging model show that the REE patterns in uncleaned core-top foraminifera resemble those adsorbed onto calcite, particulate organic material, and hydrous ferric oxides but the full extent of the REE fractionation measured in foraminifera was not reproduced by the model. However, differences in the HREE/LREE and MREE/MREE* ratios and the cerium anomaly between ocean basins are preserved and are in agreement with the seawater REE distribution. Under oxic conditions, the HREE/LREE and MREE/MREE* compositions of uncleaned foraminifera at the sediment/seawater boundary are preserved during burial but the cerium anomaly is sensitive to burial depth. In suboxic sedimentary environments, all uncleaned foraminiferal REE concentrations are elevated relative to core-top values indicating addition of REEs from pore waters. The HREE/LREE ratio is highest when sedimentation rates were greatest and when high Fe/Ca ratios in the uncleaned foraminifera indicate that Fe was mobile. In sediments that have not experienced suboxic conditions during burial, uncleaned foraminifera preserve the seawater signal taken up at the sediment/seawater interface and are therefore suggested to be a suitable archive of changes in the REE signal of past bottom waters.

Fish debris record the hydrothermal activity in the Atlantis II deep sediments (Red Sea)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oudin, E.; Cocherie, A.

1988-01-01

The REE and U, Th, Zr, Hf, Sc have been analyzed in samples from Atlantis II and Shaban/Jean Charcot Deeps in the Red Sea. The high Zr/Hf ratio in some sediments indicates the presence of fish debris or of finely crystallized apatite. The positive ..sigma..REE vs P/sub 2/O/sub 5/ and ..sigma..REE vs Zr/Hf correlations show that fish debris and finely crystallized apatite are the main REE sink in Atlantis II Deep sediments as in other marine environments. The hydrothermal sediments and the fish debris concentrates have similar REE patterns, characterized by a LREE enrichment and a large positive Eu anomaly.more » This REE pattern is also observed in E.P.R. hydrothermal solutions. Fish debris from marine environments acquire their REE content and signature mostly from sea water during early diagenesis. The hydrothermal REE signature of Atlantis II Deep fish debris indicate that they probably record the REE signature of their hydrothermal sedimentation and diagenetic environment. The different REE signatures of the Shaban/Jean Charcot and Atlantis II Deep hydrothermal sediments suggest a sea water-dominated brine in the Shaban/Jean Charcot Deep as opposed to the predominantly hydrothermal brine in Atlantis II Deep. Atlantis II Deep fish debris are also characterized by their high U but low Th contents. Their low Th contents probably reflect the low Th content of the various possible sources (sea water, brine, sediments). Their U contents are probably controlled by the redox conditions of sedimentation.« less

Magnesium and Titanium Isotopic Compositions of an Unusual Hibonite-Perovskite Refractory Inclusion from Allende: It Is Fun

NASA Technical Reports Server (NTRS)

Liu, M.-C.; Keller, L. P.; McKeegan, K. D.

2016-01-01

Introduction: Hibonite-rich refractory inclusions are among the first solids that formed in the solar nebula, and thus provide constraints on the earliest environment in the Solar System. An unusual hibonite-perovskite inclusion from Allende, SHAL, consists of a large (approximately 500 by 200 microns) single hibonite crystal and coexisting blocky perovskite (approximately 200 microns in size). The hibonite is characterized by chemical and oxygen isotopic compositions similar to those in the FUN (Fractionated and Unknown Nuclear anomalies) inclusion HAL. However, the rare earth element (REE) patterns measured at different spots of SHAL hibonite are highly variable, ranging from Group II-like (light REEs enriched relative to heavy REEs) to Group III-like (relatively flat with slight Eu depletions), but overall contrast largely with that of HAL, especially in the Ce and Yb abundances. This implies that SHAL hibonite formed and underwent distillation processes under more reducing conditions. Interestingly, the accompanying perovskite has uniform, unfractionated oxygen isotopic compositions (averaging delta (sup 17) O equals delta (sup 18) O equals -7 per mille) and REE abundances that are completely different from those of SHAL hibonite. This has been interpreted that perovskite and hibonite may not be co-genetic. Here we performed Al-Mg and Ti isotopic measurements of SHAL hibonite and perovskite to determine if the FUN characteristics are observed in these two isotope systems, and to further constrain the origin and evolution of SHAL. Results: Isotopic measurements of Al-Mg and Ti in SHAL were performed on the UCLA CAMECA ims-1290 ion microprobe by following the analytical protocols described in [1]. The Al-Mg and Ti data obtained in both terrestrial standards and SHAL hibonite and perovskite are shown below. Both SHAL hibonite and perovskite, despite very high (sup 27) Al to (sup 24) Mg ratios, are devoid of (sup 26) Mg excesses that can be attributed to the decay of (sup 26) Al. Delta (sup 25) Mg (mass-dependent fractionation) in hibonite is approximately -5 per mille per atomic mass unit relative to Madagascar hibonite, but is not well constrained for perovskite due to very large uncertainties owing to extremely low Mg contents. Similar to Mg isotopes, SHAL hibonite and perovskite show essentially the same Ti isotopic compositions, with anomalies in (sup 50) Ti of approximately 14 per mille, but the former shows greater Ti isotope fractionation than the latter (2.5 per mille per atomic mass unit versus 0 per mille). Discussion and Conclusions: The Al-Mg and Ti isotopic compositions of SHAL hibonite are consistent with those of HAL, suggesting that SHAL hibonite is a FUN inclusion and likely formed prior to homogenization of (sup 26) Al and Ti isotope variations in the solar nebula. However, the formation mechanisms for SHAL and HAL differ, given the differences in the REE patterns and degrees of oxygen mass-dependent fractionation. The Group-II to Group-III like REE patterns, the Yb depletions, and negative delta (sup 25) Mg observed in SHAL hibonite are all consistent with condensation of the hibonite precursor in a reducing environment.. The lack of large Ce depletions in SHAL hibonite implies that distillation processes that fractionated hibonite's oxygen isotopes must have taken place under a reducing condition, but the extent to which SHAL hibonite was distilled appears to be less than HAL because of the smaller degree of oxygen mass-dependent fractionation. The perovskite shares essentially the same Ti and Mg isotopic compositions as hibonite and probably formed in the same reservoir.. The ultrarefractory REE pattern seen in perovskite likely resulted from gas-solid fractionation which depleted HREEs in this reservoir. This process also explains why SHAL hibonite is generally depleted in HREEs relative to LREEs.

[Rare earth elements contents and distribution characteristics in nasopharyngeal carcinoma tissue].

PubMed

Zhang, Xiangmin; Lan, Xiaolin; Zhang, Lingzhen; Xiao, Fufu; Zhong, Zhaoming; Ye, Guilin; Li, Zong; Li, Shaojin

2016-03-01

To investigate the rare earth elements(REEs) contents and distribution characteristics in nasopharyngeal carcinoma( NPC) tissue in Gannan region. Thirty patients of NPC in Gannan region were included in this study. The REEs contents were measured by tandem mass spectrometer inductively coupled plasma(ICP-MS/MS) in 30 patients, and the REEs contents and distribution were analyzed. The average standard deviation value of REEs in lung cancer and normal lung tissues was the minimum mostly. Light REEs content was higher than the medium REEs, and medium REEs content was higher than the heavy REEs content. REEs contents changes in nasopharyngeal carcinoma were variable obviously, the absolute value of Nd, Ce, Pr, Gd and other light rare earth elements were variable widely. The degree of changes on Yb, Tb, Ho and other heavy rare earth elements were variable widely, and there was presence of Eu, Ce negative anomaly(δEu=0. 385 5, δCe= 0. 523 4). The distribution characteristic of REEs contents in NPC patients is consistent with the parity distribution. With increasing atomic sequence, the content is decline wavy. Their distribution patterns were a lack of heavy REEs and enrichment of light REEs, and there was Eu , Ce negative anomaly.

Eocene to Oligocene volcanism in the Mariana fore-arc and crustal melting

NASA Astrophysics Data System (ADS)

Hartman, B.; Reagan, M.; Hickey-Vargas, R.; Hanan, B.; Blichert-Toft, J.

2003-04-01

Recently collected volcanic rocks from the Mariana fore-arc islands of Saipan and Rota provide evidence that the genesis of silicic magmas in the IBM system involves extensive crustal melting. Rhyolites from the island of Saipan are unusually high in silica for an oceanic island arc setting. They also are unique in the Izu-Bonin-Mariana (IBM) system in that they erupted during the earliest stages of subduction (45--46 Ma), but have "mature arc" major element, trace element, and isotopic compositions. For example, the rhyolites have flat REE patterns and pronounced negative Nb anomalies. These trace element patterns are nearly identical to those Oligocene (36--32 Ma) "early arc" andesites and dacites on Saipan, Guam, and Rota. All of the aforementioned lavas also have similar 207Pb/204Pb and 208Pb/204Pb values that plot along a trend that stretches from West Philippine basin basalt compositions toward those Pacific siliceous sediments. In contrast, Eocene volcanic rocks from other locations in the IBM arc are basaltic to boninitic and have U-shaped REE patterns and small to nonexistent Nb anomalies. The Pb isotopic compositions of these samples are similar to Pacific basin volcanics and volcanogenic sediments. Mathematical modeling suggests that the Saipan rhyolites were most likely derived by partial melting of an arc-like amphibolite crust and not through crystal fractionation of a "protoarc" boninite series magma. The data and these modelings suggest that a piece of preexisting arc-like amphibolite crust was trapped in the Mariana fore-arc early in its evolution. The Saipan rhyolites were produced by melting this crust at relatively shallow depths.

Lunar Ferroan Anorthosite Petrogenesis: Clues from Trace Element Distributions in FAN Subgroups

NASA Astrophysics Data System (ADS)

Floss, Christine; James, Odette B.; McGee, James J.; Crozaz, Ghislaine

1998-04-01

The rare earth elements (REE) and selected other trace elements were measured in plagioclase and pyroxene from nine samples of the lunar ferroan anorthosite (FAN) suite of rocks. Samples were selected from each of four FAN subgroups previously defined by James et al. (1989). Plagioclase compositions are homogeneous within each sample, but high- and low-Ca pyroxenes from lithic clasts typically have different REE abundances from their counterparts in the surrounding granulated matrices. Measured plagioclase/low-Ca pyroxene concentration ratios for the REE have steeper patterns than experimentally determined plagioclase/low-Ca pyroxene partition coefficients in most samples. Textural and trace element evidence suggest that, although subsolidus equilibration may be responsible for some of the discrepancy, plagioclase compositions in most samples have been largely unaffected by intermineral redistribution of the REE. The REE systematics of plagioclase from the four subgroups are broadly consistent with their derivation through crystallization from a single evolving magma. However, samples from some of the subgroups exhibit a decoupling of plagioclase and pyroxene compositions that probably reflects the complexities inherent in crystallization from a large-scale magmatic system. For example, two anorthosites with very magnesian mafic minerals have highly evolved trace element compositions; major element compositions in plagioclase also do not reflect the evolutionary sequence recorded by their REE compositions. Finally, a noritic anorthosite breccia with relatively ferroan mafic minerals contains several clasts with high and variable REE and other trace element abundances. Although plagioclase REE compositions are consistent with their derivation from a magma with a KREEPy trace element signature, very shallow REE patterns in the pyroxenes suggest the addition of a component enriched in the light REE.

Comparing REE distribution in GEMAS agricultural soils and FOREGS topsoils-subsoils in Italy and Sweden

NASA Astrophysics Data System (ADS)

Petrosino, Paola; Sadeghi, Martiya; Andersson, Madelen; Albanese, Stefano; Dinelli, Enrico; Valera, Paolo; Ladenberger, Anna; Morris, George; Uhlbäck, Jo; Lima, Annamaria; De Vivo, Benedetto

2014-05-01

Scientific interest on Rare Earth Elements (REEs)-bearing media is increasing as a consequence of the rapidly growing demand of these important chemical resources, which are currently used in a large number of technical applications. In this study, Italian and Swedish REE data from the FOREGS database on topsoil and subsoils samples have been compared to the distribution of REEs in the GEMAS samples of agricultural soil (Ap), pertaining to regularly ploughed land to a depth of 20 cm. Principal Component Analysis (PCA) was carried out to identify patterns within both data sets. Investigation of the spatial distribution of REEs in FOREGS topsoil-subsoil and GEMAS Ap media for both countries revealed the prominent role of the geogenic component in the general REE geochemical pattern of the three solid media. Despite a similar REE content in the underlying parent material or bedrocks (alkaline igneous rocks, both intrusive and effusive in Italy, alkaline granites and pegmatites in Sweden), several distinct differences emerged between the two countries driven by climate, topography, age of the rock units and sediments, presence of mineralisations, type of soils and presence of glacial deposits. GEMAS agricultural soils form both countries show higher REEs contents than the corresponding subsoils and topsoils, which could be ascribed to the analytical method specifically set for REEs and the last generation ICP-MS instrument used by SGS Lab to analyze REEs in Ap soils. The REE content in Italian topsoil and subsoil is similar and there is a good agreement between the topsoils and Ap soils, which were collected from similar depth. Swedish subsoil is on the contrary more enriched in REEs with respect to topsoil, and Ap soils even display REE contents higher than subsoils. This anomalous REE concentrations in agricultural soil may originate from the fact that most of the arable land in Sweden has been located on glacial and postglacial deposits, rich in clay which has tendency to accumulate secondary REEs. We concluded that the fingerprints of anthropic activity due to agricultural activities does not influence the geogenic signal. Both in Italy and Sweden, in fact, REE trends in GEMAS agricultural soils are well comparable with those obtained for FOREGS soils sampled from unoccupied and undisturbed regions.

Fractionation in the solar nebula - Condensation of yttrium and the rare earth elements

NASA Technical Reports Server (NTRS)

Boynton, W. V.

1975-01-01

The condensation of Y and the rare earth elements (REE) from the solar nebula may be controlled by thermodynamic equilibrium between gas and condensed solids. Highly fractionated REE patterns may result if condensates are removed from the gas before condensation is complete. It is found that the fractionation is not a smooth function of REE ionic radius but varies in an extremely irregular pattern. Both Yb and Eu are predicted to be extremely depleted in the early condensate without the requirement of condensation in the divalent state. The model is discussed with respect to a highly fractionated pattern observed by Tanaka and Masuda (1973), in a pink Ca-Al-rich inclusion from the Allende meteorite and can account for the abundances of each REE determined. According to the model this inclusion represents a condensate from a previously fractionated gas rather than from a gas of solar composition. Before the condensation of this inclusion, an earlier condensate was formed and was removed from equilibrium with the gas.

The formation and trace elements of garnet in the skarn zone from the Xinqiao Cu-S-Fe-Au deposit, Tongling ore district, Anhui Province, Eastern China

NASA Astrophysics Data System (ADS)

Xiao, Xin; Zhou, Tao-fa; White, Noel C.; Zhang, Le-jun; Fan, Yu; Wang, Fang-yue; Chen, Xue-feng

2018-03-01

Xinqiao is a large copper-gold deposit and consists of two major mineralization types: stratabound and skarn. The skarn occurs along the contact between a quartz diorite intrusion and Carboniferous-Triassic limestone. Xinqiao has a strongly developed skarn zone, including endoskarn and exoskarn; the exoskarn is divided into proximal and distal exoskarn. We present systematic major, trace and rare earth element (REE) concentrations for garnets from the skarn zone, discuss the factors controlling the incorporation of trace elements into the garnets, and constrain the formation and evolution of the garnet from skarn zone in Xinqiao deposit. Grossular (Adr20-44Grs56-80) mostly occurs in endoskarn and has typical HREE-enriched and LREE-depleted patterns, with small Eu anomalies and low ∑REE. Garnets from the exoskarn show complex textures and chemical compositions. The composition of garnets range from Al-rich andradite (Adr63-81Grs19-47) to andradite (Adr67-98Grs2-33). Garnet in endoskarn has typical HREE-enriched and LREE-depleted patterns. Al-rich andradite in proximal skarn has small Eu anomalies and moderate ∑REE. Andradite from distal exoskarn shows strong positive Eu anomalies and has variable ∑REE. The U, Y, Fe and Al relationship with ∑REE shows that two mechanisms controlled incorporation of REE into the garnets: crystal chemistry (substitution and interstitial solid solution) mainly controlled in the endoskarn garnet (grossular) and the proximal exoskarn (Al-rich andradite), and fluid and rock chemistry (surface adsorption and occlusion) controlled REEs in the distal exoskarn. Furthermore, Al has a negative relationship with ∑REE indicating that REE3+ did not follow a coupled, YAG-type substitution into the garnets. Variations in textures and trace and rare earth elements of garnets suggest that the garnets in the endoskarn formed by slow crystal growth at low W/R ratios and near-neutral pH in a closed system during periods of diffusive metasomatism. The garnets in the exoskarn formed rapidly from externally derived fluids during advective metasomatism, and adsorption had a major control on the REE patterns in distal exoskarn. With the end of water-rock reaction, the contents of REE decreased in the hydrothermal fluid, and the system became nearly closed.

Rare earth element patterns in Archean high-grade metasediments and their tectonic significance

NASA Technical Reports Server (NTRS)

Taylor, Stuart Ross; Rudnick, Roberta L.; Mclennan, Scott M.; Eriksson, Kenneth A.

1986-01-01

REE data on metasedimentary rocks from two different types of high-grade Archean terrains are presented and analyzed. The value of REEs as indicators of crustal evolution is explained; the three geologic settings (in North America, Southern Africa, and Australia) from which the samples were obtained are described; and the data are presented in extensive tables and graphs and discussed in terms of metamorphic effects, the role of accessory phases, provenance, and tectonic implications (recycling, the previous extent of high-grade terrains, and a model of Archean crustal growth). The diversity of REE patterns in shallow-shelf metasediments is attributed to local provenance, while the Eu-depleted post-Archean patterns are associated with K-rich plutons from small, stable early Archean terrains.

Rare earth element variations resulting from inversion of pigeonite and subsolidus reequilibration in lunar ferroan anorthosites

USGS Publications Warehouse

James, O.B.; Floss, C.; McGee, J.J.

2002-01-01

We present results of a secondary ion mass spectrometry study of the rare earth elements (REEs) in the minerals of two samples of lunar ferroan anorthosite, and the results are applicable to studies of REEs in all igneous rocks, no matter what their planet of origin. Our pyroxene analyses are used to determine solid-solid REE distribution coefficients (D = CREE in low-Ca pyroxene/CREE in augite) in orthopyroxene-augite pairs derived by inversion of pigeonite. Our data and predictions from crystal-chemical considerations indicate that as primary pigeonite inverts to orthopyroxene plus augite and subsolidus reequilibration proceeds, the solid-solid Ds for orthopyroxene-augite pairs progressively decrease for all REEs; the decrease is greatest for the LREEs. The REE pattern of solid-solid Ds for inversion-derived pyroxene pairs is close to a straight line for Sm-Lu and turns upward for REEs lighter than Sm; the shape of this pattern is predicted by the shapes of the REE patterns for the individual minerals. Equilibrium liquids calculated for one sample from the compositions of primary phases, using measured or experimentally determined solid-liquid Ds, have chondrite-normalized REE patterns that are very slightly enriched in LREEs. The plagioclase equilibrium liquid is overall less rich in REEs than pyroxene equilibrium liquids, and the discrepancy probably arises because the calculated plagioclase equilibrium liquid represents a liquid earlier in the fractionation sequence than the pyroxene equilibrium liquids. "Equilibrium" liquids calculated from the compositions of inversion-derived pyroxenes or orthopyroxene derived by reaction of olivine are LREE depleted (in some cases substantially) in comparison with equilibrium liquids calculated from the compositions of primary phases. These discrepancies arise because the inversion-derived and reaction-derived pyroxenes did not crystallize directly from liquid, and the use of solid-liquid Ds is inappropriate. The LREE depletion of the calculated liquids is a relic of formation of these phases from primary LREE-depleted minerals. Thus, if one attempts to calculate the compositions of equilibrium liquids from pyroxene compositions, it is important to establish that the pyroxenes are primary. In addition, our data suggest that experimental studies have underestimated solid-liquid Ds for REEs in pigeonite and that REE contents of liquids calculated using these Ds are overestimates. Our results have implications for Sm-Nd age studies. Our work shows that if pigeonite inversion and/or subsolidus reequilibration between augite and orthopyroxene occured significantly after crystallization, and if pyroxene separates isolated for Sm-Nd studies do not have the bulk composition of the primary pyroxenes, then the Sm-Nd isochron age and ??Nd will be in error. Copyright ?? 2002 Elsevier Science Ltd.

Geochemistry of the suspended sediment in the estuaries of the Mandovi and Zuari rivers, central west coast of India.

PubMed

Kessarkar, Pratima M; Shynu, R; Rao, V Purnachandra; Chong, Feng; Narvekar, Tanuja; Zhang, Jing

2013-05-01

The geochemistry of the suspended particulate matter (SPM) collected during the monsoon was determined to identify the sources of SPM and to understand the physicochemical processes in the Mandovi and Zuari river estuaries. The concentrations of SPM decrease seaward in both estuaries, but are relatively high at bay stations. Kaolinite is the most dominant clay mineral in the upstream of both rivers. Smectite increases seaward in both estuaries and is abundant in the bay. Upstream stations of Mandovi, where ore deposits are stored on the shore, exhibit high Fe, Mn, total rare earth elements (∑REE), and middle REE- and heavy REE-enriched patterns. Channel stations of both estuaries exhibit middle REE- and light REE-enriched patterns, which gradually changed seaward to middle REE- and heavy REE-enriched patterns. Canal stations exhibit the highest concentrations of major and trace metals. High metal/Al ratios occur at stations in the upstream of Zuari and at the confluence of canals in the Mandovi estuary. Enrichment factors of metals indicate that Mn is significantly polluted while other metals are moderately polluted. The δ(13)C and δ(15)N of organic matter indicate that the terrigenous organic matter at the upstream is diluted seaward by marine organic matter. Organic matter at bay stations is largely marine and altered-type. The compositions of SPM are controlled by the particulates from ore dust, the geology of the drainage basins, and the physicochemical processes in the estuaries. Particulates resuspended from the bay are dominated by ore dust, which are advected into the channels of both estuaries during the lull periods of the monsoon.

Geochemistry of the Archean Yellowknife Supergroup

NASA Astrophysics Data System (ADS)

Jenner, G. A.; Fryer, B. J.; McLennan, S. M.

1981-07-01

The Archean Yellowknife Supergroup (Slave Structural Province. Canada) is composed of a thick sequence of supracrustal rocks, which differs from most Archean greenstone belts in that it contains a large proportion ( ~ 80%) of sedimentary rocks. Felsic volcanics of the Banting Formation are characterized by HREE depletion without Eu-anomalies, indicating an origin by small degrees of partial melting of a mafic source, with minor garnet in the residua. Granitic rocks include synkinematic granites [HREE-depleted; low ( 87Sr /86Sr ) I], post-kinematic granites [negative Eu-anomalies, high ( 87Sr /86Sr ) I] and granitic gneisses with REE patterns similar to the post-kinematic granites. Sedimentary rocks (turbidites) of the Burwash and Walsh Formations have similar chemical compositions and were derived from 20% mafic-intermediate volcanics, 55% felsic volcanics and 25% granitic rocks. Jackson Lake Formation lithic wackes can be divided into two groups with Group A derived from 50% mafic-intermediate volcanics and 50% felsic volcanics and Group B, characterized by HREE depletion, derived almost exclusively from felsic volcanics. REE patterns of Yellowknife sedimentary rocks are similar to other Archean sedimentary REE patterns, although they have higher La N/Yb N. These patterns differ significantly from typical post-Archean sedimentary REE patterns, supporting the idea that Archean exposed crust had a different composition than the present day exposed crust.

The rare earth element geochemistry on surface sediments, shallow cores and lithological units of Lake Acıgöl basin, Denizli, Turkey

NASA Astrophysics Data System (ADS)

Budakoglu, Murat; Abdelnasser, Amr; Karaman, Muhittin; Kumral, Mustafa

2015-11-01

The sediments in Lake Acıgöl, located in SW Anatolia, Turkey, were formed under tectono-sedimentary events. REE geochemical investigations of the Lake Acıgöl sediments, from surface and shallow core sediments at different depths (0-10 cm, 10-20 cm and 20-30 cm) are presented to clarify the characteristics of REE and the nature of source rocks in the lake sediments' and to deduce their paleoenvironmental proxies. The chondrite-normalized REE patterns of these sediments are shown as light enrichment in LREE and flat HREE with a negative Eu anomaly that is close to the continental collision basin (CCB) in its profile; this is not comparable with PAAS and UCC. Inorganic detrital materials control the REE characteristics of the Lake Acıgöl sediments and these sediments were accumulated in oxic and dysoxic depositional conditions and/or at passive margins derived from oceanic island arc rocks. They were affected by low chemical weathering, either at the original source or during transport, before deposition under arid or subtropical humid climatic conditions. In addition, we used GIS techniques (such as Inverse Distance Weighted (IDW) and Geographically Weighted Regression (GWR)) to investigate the spatial interpolation and spatial correlation of the REEs from the lake surface sediments in Lake Acıgöl and its surrounding lithological units. GIS techniques showed that the lithological units (e.g., Hayrettin Formation) north of Lake Acıgöl have high REE contents; however, Eu/Eu∗ values were higher in some lake surface sediments than in lithological units, and that refers to a negative Eu-anomaly. Therefore, Lake Acıgöl sediments are derived from the weathered products, mainly from local, highly basic bedrock around the lake from the Archean crust. The chronology of Lake Acıgöl sediment was conducted using the Constant Rate of Supply (CRS) model. Using the CRS methods for the calculation of sedimentation rate, we obtained a 0.012 g/cm2/year value which is an average value for the first 20 cm depth of this lake. The core activity profiles of 210Pb and 137Cs were measured to estimate the age of the sediments; we observed activities of 8.08 ± 5.5 Bq/kg for 210Pb and 0.86 ± 0.6 Bq/kg for 137Cs.

An impact of moss sample cleaning on uncertainty of analytical measurement and pattern profiles of rare earth elements.

PubMed

Dołęgowska, Sabina; Gałuszka, Agnieszka; Migaszewski, Zdzisław M

2017-12-01

The main source of rare earth elements (REE) in mosses is atmospheric deposition of particles. Sample treatment operations including shaking, rinsing or washing, which are made in a standard way on moss samples prior to chemical analysis, may lead to removing particles adsorbed onto their tissues. This in turn causes differences in REE concentrations in treated and untreated samples. For the present study, 27 combined moss samples were collected within three wooded areas and prepared for REE determinations by ICP-MS using both manual cleaning by shaking and triple rinsing with deionized water. Higher concentrations of REE were found in manually cleaned samples. The comparison of REE signatures and shale-normalized REE concentration patterns showed that the treatment procedure did not lead to fractionation of REE. All the samples were enriched in medium rare earth elements, and the δMREE factor remained practically unchanged after rinsing. Positive anomalies of Nd, Sm, Eu, Gd, Er and Yb were observed in both, manually cleaned and rinsed samples. For all the elements examined, analytical uncertainty was below 3.0% whereas sample preparation uncertainty computed with ANOVA, RANOVA, modified RANOVA and range statistics methods varied from 3.5 to 29.7%. In most cases the lowest s rprep values were obtained with the modified RANOVA method. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rare earth and other elements in components of the Abee enstatite chondrite

NASA Technical Reports Server (NTRS)

Frazier, R. M.; Boynton, W. V.

1985-01-01

Radiochemical and instrumental neutron activation analyses of REEs and other elements have been conducted for Abee clast samples, a matrix sample, a dark inclusion, magnetic and nonmagnetic samples, and bulk samples. Correlations of the REEs and oldhamite abundance for both the clasts and dark inclusions indicate that the REEs chiefly occur in oldhamite. The similar REE patterns for clasts and dark inclusions, and the similar mineral composition of oldhamite in clast and dark inclusions, suggest that the oldhamite in both the clasts and dark inclusions is of a common origin.

Generation of felsic rocks of bimodal volcanic suites from thinned and rifted continental margins: Geochemical and Nd, Sr, Pb-isotopic evidence from Haida Gwaii, British Columbia, Canada

NASA Astrophysics Data System (ADS)

Dostal, Jaroslav; Hamilton, Tark S.; Shellnutt, J. Gregory

2017-11-01

The compositionally bimodal volcanic rocks of the Eocene-Miocene Masset Formation from Queen Charlotte basin, Haida Gwaii, British Columbia, Canada, underlie an area greater than 5000 km2 where their exposed sections are up to 1.6 km thick. The suite of mafic and felsic rocks (dacites and rhyolites) that erupted closely spaced in time, in both submarine and subaerial conditions, was associated with significant crustal extension and thin continental crust ( 19-24 km thick), with volcanism persisting for 35 Ma (from 46 to 11 Ma). Predominant mafic types (mafic:felsic 2:1) are moderately enriched mid-ocean-ridge-like basalts that were derived by a partial melting of a heterogeneous spinel peridotite source. Felsic rocks are plagioclase-phyric, two pyroxene-bearing, mainly peraluminous types which have Nd, Pb and Sr isotopic compositions overlapping those of basalts including high positive ƐNd(t) values (up to >+6). The chondrite-normalized REE patterns show light REE enrichment but flat heavy REE along with a variable negative Eu anomaly. Mineralogy, major and trace elements, Nd-Sr-Pb isotopic data and model calculations using MELTS are consistent with a derivation of felsic rocks from the basalts by fractional crystallization. The intercalation of basaltic and felsic rocks suggests the existence of separate, simultaneously active plumbing and feeder systems and relatively stable magma chamber(s) to generate large volumes of differentiated felsic magmas by fractional crystallization. The Masset rocks provide an example for the generation of felsic magmas of bimodal volcanic suites during rifting along a thinned continental margin. Appendix 1b Representative analyses of minerals of the Masset Formation felsic rocks

Chemical and oxygen isotopic properties of ordinary chondrites (H5, L6) from Oman: Signs of isotopic equilibrium during thermal metamorphism

NASA Astrophysics Data System (ADS)

Ali, Arshad; Nasir, Sobhi J.; Jabeen, Iffat; Al Rawas, Ahmed; Banerjee, Neil R.; Osinski, Gordon R.

2017-10-01

Mean bulk chemical data of recently found H5 and L6 ordinary chondrites from the deserts of Oman generally reflect isochemical features which are consistent with the progressive thermal metamorphism of a common, unequilibrated starting material. Relative differences in abundances range from 0.5-10% in REE (Eu = 14%), 6-13% in siderophile elements (Co = 48%), and >10% in lithophile elements (exceptions are Ba, Sr, Zr, Hf, U = >30%) between H5 and L6 groups. These differences may have accounted for variable temperature conditions during metamorphism on their parent bodies. The CI/Mg-normalized mean abundances of refractory lithophile elements (Al, Ca, Sm, Yb, Lu, V) show no resolvable differences between H5 and L6 suggesting that both groups have experienced the same fractionation. The REE diagram shows subtle enrichment in LREE with a flat HREE pattern. Furthermore, overall mean REE abundances are 0.6 × CI with enriched La abundance ( 0.9 × CI) in both groups. Precise oxygen isotope compositions demonstrate the attainment of isotopic equilibrium by progressive thermal metamorphism following a mass-dependent isotope fractionation trend. Both groups show a slope-1/2 line on a three-isotope plot with subtle negative deviation in Δ17O associated with δ18O enrichment relative to δ17O. These deviations are interpreted as the result of liberation of water from phyllosilicates and evaporation of a fraction of the water during thermal metamorphism. The resultant isotope fractionations caused by the water loss are analogous to those occurring between silicate melt and gas phase during CAI and chondrule formation in chondrites and are controlled by cooling rates and exchange efficiency.

Water Content in the SW USA Mantle Lithosphere: FTIR Analysis of Dish Hill and Kilbourne Hole Pyroxenites

NASA Technical Reports Server (NTRS)

Gibler, Robert; Peslier, Anne H.; Schaffer, Lillian Aurora; Brandon, Alan D.

2014-01-01

Kilbourne Hole (NM, USA) and Dish Hill (CA, USA) mantle xenoliths sample continental mantle in two different tectonic settings. Kilbourne Hole (KH) is located in the Rio Grande rift. Dish Hill (DH) is located in the southern Mojave province, an area potentially affected by subduction of the Farallon plate beneath North America. FTIR analyses were obtained on well characterized pyroxenite, dunite and wehrlite xenoliths, thought to represent crystallized melts at mantle depths. PUM normalized REE patterns of the KH bulk-rocks are slightly LREE enriched and consistent with those of liquids generated by < 5% melting of a spinel peridotite source. Clinopyroxenes contain from 272 to 313 ppm weight H2O similar to the lower limit of KH peridotite clinopyroxenes (250-530 ppm H2O). This is unexpected as crystallized melts like pyroxenites should concentrate water more than residual mantle-like peridotites, given that H is incompatible. PUM normalized bulk REE of the DH pyroxenites are characterized by flat to LREE depleted REE profiles consistent with > 6% melting of a spinel peridotite source. Pyroxenite pyroxenes have no detectable water but one DH wehrlite, which bulk-rock is LREE enriched, has 4 ppm H2O in orthopyroxene and <1ppm in clinopyroxene. The DH pyroxenites may thus come from a dry mantle source, potentially unaffected by the subduction of the Farallon plate. These water-poor melts either originated from shallow oceanic lithosphere overlaying the Farallon slab or from continental mantle formed > 2 Ga. The Farallon subduction appears to have enriched in water the southwestern United States lithospheric mantle further east than DH, beneath the Colorado plateau.

Rare earth element distribution in some hydrothermal minerals: evidence for crystallographic control

USGS Publications Warehouse

Morgan, J.W.; Wandless, G.A.

1980-01-01

Rare earth element (REE) abundances were measured by neutron activation analysis in anhydrite (CaSO4), barite (BaSO4), siderite (FeCO3) and galena (PbS). A simple crystal-chemical model qualitatively describes the relative affinities for REE substitution in anhydrite, barite, and siderite. When normalized to 'crustal' abundances (as an approximation to the hydrothermal fluid REE pattern), log REE abundance is a surprisingly linear function of (ionic radius of major cation-ionic radius of REE)2 for the three hydrothermal minerals, individually and collectively. An important exception, however, is Eu, which is anomalously enriched in barite and depleted in siderite relative to REE of neighboring atomic number and trivalent ionic radius. In principle, REE analyses of suitable pairs of co-existing hydrothermal minerals, combined with appropriate experimental data, could yield both the REE content and the temperature of the parental hydrothermal fluid. The REE have only very weak chalcophilic tendencies, and this is reflected by the very low abundances in galena-La, 0.6 ppb; Sm, 0.06 ppb; the remainder are below detection limits. ?? 1980.

Mobility of rare earth element in hydrothermal process and weathering product: a review

NASA Astrophysics Data System (ADS)

Lintjewas, L.; Setiawan, I.

2018-02-01

The Rare Earth Element (REE), consists of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Lu, Ho, Er, Tm, Yb, are important elements to be used as raw materials of advanced technology such as semiconductors, magnets, and lasers. The research of REE in Indonesia has not been done. Several researches were conducted on granitic rocks and weathering product such as Bangka, Sibolga, West Kalimantan, West Sulawesi and Papua. REE can be formed by hydrothermal processes such as Bayan Obo, South China. The REE study on active hydrothermal system (geothermal) in this case also has the potential to produce mineral deposits. The purpose of this review paper is to know the mobility of REE on hydrothermal process and weathering products. Mobility of REE in the hydrothermal process can change the distribution patterns and REE content such as Ce, Eu, La, Lu, Nd, Sm, and Y. Another process besides the hydrothermal is weathering process. REE mobility is influenced by weathering products, where the REE will experience residual and secondary enrichment processes in heavier minerals.

Xenotime-(Y) formation from zircon dissolution-precipitation and HREE fractionation: an example from a metamorphosed phosphatic sandstone, Espinhaço fold belt (Brazil)

NASA Astrophysics Data System (ADS)

Franz, Gerhard; Morteani, Giulio; Rhede, Dieter

2015-10-01

We present an example where xenotime-(Y) together with metamorphic zircon replaces detrital zircon in a phosphatic sandstone from the Mesoproterozoic Espinhaço fold belt, Brazil, in a dissolution-precipitation reaction: {{zircon}}1 ( {{relict}} ) + {{P-}}{{bearing fluid}} = {{zircon}}2 ( {{metamorphic}} ) + {{xenotime}}. During the Brasiliano orogeny at 634 ± 19 Ma, the rocks experienced amphibolite facies metamorphism at ≥0.6 GPa/ 550 ± 37 °C (Southern Espinhaço) and ≥0.6 GPa/ 570 ± 35 °C (Northern Espinhaço), constrained by Zr-in-rutile and Ti-in-quartz thermometry and the presence of kyanite + muscovite + quartz. Many of the rocks show unusual rare earth element (REE) patterns with a hump at Gd-Tb-Dy and depletion in light REE. Detrital zircons (with relict ages between 1.5 and 3.3 Ga) show varying degrees of replacement as indicated by the presence of xenotime and associated porosity, from almost pristine to complete alteration. Textural evidence indicates local mobility of Zr and REE at the scale of the thin section. Xenotime-(Y) occurs together with other phosphates, mainly augelite, lazulite, and minerals of the svanbergite-crandallite-goyacite-florencite group. Xenotime-(Y) is very heterogeneous and reaches unusually high contents of up to 14 wt% Gd2O3, 13 wt% Dy2O3, and 3 wt% Tb2O3, corresponding to ≤0.36 REE atoms per formula unit due to the exchange Y = REE. The heavy REE patterns of xenotime-(Y) therefore show variable enrichment in individual elements, which explains the characteristic hump at Gd-Tb-Dy in the REE patterns of the whole rock. Although the rocks reached amphibolite facies conditions, textures indicate that formation of xenotime likely occurred during the early stages of diagenesis—metamorphism. Comparison with REE concentrations in xenotime-(Y) from the literature shows that selective REE incorporation into xenotime-(Y) is controlled by interaction with P-bearing hydrous fluids.

Excess europium content in Precambrian sedimentary rocks and continental evolution

NASA Technical Reports Server (NTRS)

Jakes, P.; Taylor, S. R.

1974-01-01

It is proposed that the europium excess in Precambrian sedimentary rocks, relative to those of younger age, is derived from volcanic rocks of ancient island arcs, which were the source materials for the sediments. Precambrian sedimentary rocks and present-day volcanic rocks of island arcs have similar REE patterns, total REE abundances, and excess Eu, relative to the North American shale composite. The present upper crustal REE pattern, as exemplified by that of sediments, is depleted in Eu, relative to chondrites. This depletion is considered to be a consequence of development of a granodioritic upper crust by partial melting in the lower crust, which selectively retains europium.

Geochemistry of rare earth elements in minesoils from São Domingos mining district (Iberian Pyrite Belt)

NASA Astrophysics Data System (ADS)

Delgado, Joaquin; Perez-Lopez, Rafael; Nieto, Jose Miguel; Ayora, Carles

2010-05-01

The São Domingos mine is one of the most emblematic mining districts in the lower part of the Guadiana River Basin (SW of Iberian Peninsula). It is located in Portugal (about 5 km from the Spanish border), in the northern sector of the Iberian Pyrite Belt (IPB), one of the largest metallogenetic provinces of massive sulphides in the world. Although mining activity has ceased at present, the large-scale exploitation of this deposit between the second half of the XIX century and the first half of the XX century, has favoured the production of enormous waste dumps, where oxidation of pyrite and associated sulphides is resulting in the production of acid mine drainage (AMD). Mining wastes, minesoils, and acid mine drainage have been analyzed for their major ions and rare earth elements (REE) with the aim of understanding the REE mobility during sulphide weathering so that lanthanoid series can be used both as a proxy for the extent of water-rock interaction and as a tool for identifying impacts of AMD on natural ecosystems. Chemical speciation of REE in extracts from minesoils indicates that REE sulphate complexes (mainly LnSO4+) are the primary aqueous form (60-90%), and free ionic species (Ln3+, 10-40%) are the next most abundant form of soil water-soluble fraction and controls the REE speciation model. The REE from this fraction have NASC-normalized patterns with middle-REE (MREE) enriched signature compared to the light-REE (LREE) and heavy-REE (HREE), showing convex MREE-signatures and convexity index values of +1.29 +/- 1.13. These results are consistent with the typical REE fractionation patterns reported for AMD. Poorly crystalline iron oxyhydroxysulphates act as a source of labile MREE by dissolution and/or desorption processes and could explain the MREE-enriched signatures in solution.

Using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to explore geochemical taphonomy of vertebrate fossils in the upper cretaceous two medicine and Judith River formations of Montana

USGS Publications Warehouse

Rogers, R.R.; Fricke, H.C.; Addona, V.; Canavan, R.R.; Dwyer, C.N.; Harwood, C.L.; Koenig, A.E.; Murray, R.; Thole, J.T.; Williams, J.

2010-01-01

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to determine rare earth element (REE) content of 76 fossil bones collected from the Upper Cretaceous (Campanian) Two Medicine (TMF) and Judith River (JRF) Formations of Montana. REE content is distinctive at the formation scale, with TMF samples exhibiting generally higher overall REE content and greater variability in REE enrichment than JRF samples. Moreover, JRF bones exhibit relative enrichment in heavy REE, whereas TMF bones span heavy and light enrichment fields in roughly equal proportions. TMF bones are also characterized by more negative Ce anomalies and greater U enrichment than JRF bones, which is consistent with more oxidizing diagenetic conditions in the TMF. Bonebeds in both formations show general consistency in REE content, with no indication of spatial or temporal mixing within sites. Previous studies, however, suggest that the bonebeds in question are attritional assemblages that accumulated over considerable time spans. The absence of geochemical evidence for mixing is consistent with diagenesis transpiring in settings that remained chemically and hydrologically stable during recrystallization. Lithology-related patterns in REE content were also compared, and TMF bones recovered from fluvial sandstones show relative enrichment in heavy REE when compared with bones recovered from fine-grained floodplain deposits. In contrast, JRF bones, regardless of lithologic context (sandstone versus mudstone), exhibit similar patterns of REE uptake. This result is consistent with previous reconstructions that suggest that channel-hosted microfossil bonebeds of the JRF developed via the reworking of preexisting concentrations embedded in the interfluve. Geochemical data further indicate that reworked elements were potentially delivered to channels in a recrystallized condition, which is consistent with rapid adsorption of REE postmortem. Copyright ?? 2010, SEPM (Society for Sedimentary Geology).

Growth Failure in Children with Intractable Epilepsy Is Not Due to Increased Resting Energy Expenditure

ERIC Educational Resources Information Center

Bergqvist, A. G. Christina; Trabulsi, Jillian; Schall, Joan I.; Stallings, Virginia A.

2008-01-01

The aim of this study was to evaluate the resting energy expenditure (REE) of children with intractable epilepsy (IE) compared with healthy children, and to determine factors that contribute to the pattern of REE. REE, growth status, and body composition were assessed in 25 prepubertal children with IE (15 males, 10 females; mean age 5y 5mo [SD 2y…

Mesosiderite clasts with the most extreme positive europium anomalies among solar system rocks

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Rubin, Alan E.; Davis, Andrew M.

1992-01-01

Pigeonite-plagioclase gabbros that occur as clasts in mesosiderites (brecciated stony-iron meteorites) show extreme fractionations of the rare-earth elements (REEs) with larger positive europium anomalies than any previously known for igneous rocks from the earth, moon, or meteorite parent bodies and greater depletions of light REEs relative to heavy REEs than known for comparable cumulate gabbros. The REE pattern for merrillite in one of these clasts is depleted in light REEs and has a large positive europium anomaly as a result of metamorphic equilibration with the silicates. The extreme REE ratios exhibited by the mesosiderite clasts demonstrate that multistage igneous processes must have occurred on some asteroids in the early solar system. Melting of the crust by large-scale impacts or electrical induction from an early T-Tauri-phase sun may be responsible for these processes.

The group separation of the rare-earth elements and yttrium from geologic materials by cation-exchange chromatography

USGS Publications Warehouse

Crock, J.G.; Lichte, F.E.; Wildeman, T.R.

1984-01-01

Demand is increasing for the determination of the rare-earth elements (REE) and yttrium in geologic materials. Due to their low natural abundance in many materials and the interferences that occur in many methods of determination, a separation procedure utilizing gradient strong-acid cation-exchange chromatography is often used to preconcentrate and isolate these elements from the host-rock matrix. Two separate gradient strong-acid cation-exchange procedures were characterized and the major elements as well as those elements thought to provide the greatest interference for the determination of the REE in geologic materials were tested for separation from the REE. Simultaneous inductively coupled argon plasma-atomic emission spectroscopy (ICAP-AES) measurements were used to construct the chromatograms for the elution studies, allowing the elution patterns of all the elements of interest to be determined in a single fraction of eluent. As a rock matrix, U.S. Geological Survey standard reference BCR-1 basalt was digested using both an acid decomposition procedure and a lithium metaborate fusion. Hydrochloric and nitric acids were tested as eluents and chromatograms were plotted using the ICAP-AES data; and we observed substantial differences in the elution patterns of the REE and as well as in the solution patterns of Ba, Ca, Fe and Sr. The nitric acid elution required substantially less eluent to elute the REE and Y as a group when compared to the hydrochloric acid elution, and provided a clearer separation of the REE from interfering and matrix elements. ?? 1984.

Rare earth elements in fine-grained sediments of major rivers from the high-standing island of Taiwan

NASA Astrophysics Data System (ADS)

Li, Chuan-Shun; Shi, Xue-Fa; Kao, Shuh-Ji; Liu, Yan-Guang; Lyu, Hua-Hua; Zou, Jian-Jun; Liu, Sheng-Fa; Qiao, Shu-Qing

2013-06-01

Thirty-eight sediment samples from 15 primary rivers on Taiwan were retrieved to characterize the rare earth element (REE) signature of fluvial fine sediment sources. Compared to the three large rivers on the Chinese mainland, distinct differences were observed in the REE contents, upper continental crust normalized patterns and fractionation factors of the sediment samples. The average REE concentrations of the Taiwanese river sediments are higher than those of the Changjiang and Huanghe, but lower than the Zhujiang. Light rare earth elements (LREEs) are enriched relative to heavy rare earth elements (HREEs) with ratios from 7.48 to 13.03. We found that the variations in (La/Lu)UCC-(Gd/Lu)UCC and (La/Yb)UCC-(Gd/Yb)UCC are good proxies for tracing the source sediments of Taiwanese and Chinese rivers due to their distinguishable values. Our analyses indicate that the REE compositions of Taiwanese river sediments were primarily determined by the properties of the bedrock, and the intensity of chemical weathering in the drainage areas. The relatively high relief and heavy rainfall also have caused the REEs in the fluvial sediments from Taiwan to be transported to the estuaries down rivers from the mountains, and in turn delivered nearly coincidently to the adjacent seas by currents and waves. Our studies suggest that the REE patterns of the river sediments from Taiwan are distinguishable from those from the other sources of sediments transported into the adjacent seas, and therefore are useful proxies for tracing the provenances and dispersal patterns of sediments, as well as paleoenvironmental changes in the marginal seas.

Production and precipitation of rare earth elements in acidic to alkaline coal mine discharges, Appalachian Basin, USA

NASA Astrophysics Data System (ADS)

Stewart, B. W.; Capo, R. C.; Hedin, B. C.; Wallrich, I. L. R.; Hedin, R. S.

2016-12-01

Abandoned coal mine discharges are a serious threat to ground and surface waters due to their high metal content and often high acidity. However, these discharges represent a potential source of rare earth elements (REE), many of which are considered to be critical resources. Trace element data from 18 coal mine drainage (CMD) sites within the Appalachian Basin suggest CMD is enriched in total REE by 1-4 orders of magnitude relative to concentrations expected in unaffected surface or ground waters. When normalized to the North American Shale Composite (NASC), the discharges generally show a pattern of enrichment in the middle REE, including several identified as critical resources (Nd, Eu, Dy, Tb). In contrast, shale, sandstone and coal samples from Appalachian Basin coal-bearing units have concentrations and patterns similar to NASC, indicating that the REE in CMD are fractionated during interaction with rock in the mine pool. The highest total REE contents (up to 2800 mg/L) are found in low-pH discharges (acid mine drainage, or AMD). A precipitous drop in REE concentration in CMD with pH ≥6.6 suggests adsorption or precipitation of REE in the mine pool at circumneutral pH. Precipitated solids from 21 CMD active and passive treatment sites in the Appalachian Basin, including Fe oxy-hydroxides, Ca-Mg lime slurries, and Si- and Al-rich precipitates, are enriched in total REE content relative to the average CMD discharges by about four orders of magnitude. Similar REE trends in the discharges and precipitates, including MREE enrichment, suggest minimal fractionation of REE during precipitation; direct comparisons over multiple seasonal cycles are needed to confirm this. Although the data are limited, Al-rich precipitates generally have high REE concentrations, while those in iron oxy-hydroxides tend to be lower. Based on the area of mined coal in the Appalachian Basin, estimated infiltration rates, and the mean REE flux from discharges analyzed in this study and that of Cravotta and Brady (2015, Appl. Geochem. 62, 108-130), we estimate that coal mine drainage outflows in this region generate approximately 450 metric tons of dissolved REE per year, a portion of which could be targeted for resource recovery during CMD treatment.

Recovering the primary geochemistry of Jack Hills zircons through quantitative estimates of chemical alteration

NASA Astrophysics Data System (ADS)

Bell, Elizabeth A.; Boehnke, Patrick; Harrison, T. Mark

2016-10-01

Despite the robust nature of zircon in most crustal and surface environments, chemical alteration, especially associated with radiation damaged regions, can affect its geochemistry. This consideration is especially important when drawing inferences from the detrital record where the original rock context is missing. Typically, alteration is qualitatively diagnosed through inspection of zircon REE patterns and the style of zoning shown by cathodoluminescence imaging, since fluid-mediated alteration often causes a flat, high LREE pattern. Due to the much lower abundance of LREE in zircon relative both to other crustal materials and to the other REE, disturbance to the LREE pattern is the most likely first sign of disruption to zircon trace element contents. Using a database of 378 (148 new) trace element and 801 (201 new) oxygen isotope measurements on zircons from Jack Hills, Western Australia, we propose a quantitative framework for assessing chemical contamination and exchange with fluids in this population. The Light Rare Earth Element Index is scaled on the relative abundance of light to middle REE, or LREE-I = (Dy/Nd) + (Dy/Sm). LREE-I values vary systematically with other known contaminants (e.g., Fe, P) more faithfully than other suggested proxies for zircon alteration (Sm/La, various absolute concentrations of LREEs) and can be used to distinguish primary compositions when textural evidence for alteration is ambiguous. We find that zircon oxygen isotopes do not vary systematically with placement on or off cracks or with degree of LREE-related chemical alteration, suggesting an essentially primary signature. By omitting zircons affected by LREE-related alteration or contamination by mineral inclusions, we present the best estimate for the primary igneous geochemistry of the Jack Hills zircons. This approach increases the available dataset by allowing for discrimination of on-crack analyses (and analyses with ambiguous or no information on spot placement or zircon internal structures) that do not show evidence for chemical alteration. It distinguishes between altered and unaltered samples in ambiguous cases (e.g., relatively high Ti), identifying small groups with potentially differing provenance from the main Jack Hills population. Finally, filtering of the population using the LREE-I helps to more certainly define primary correlations among trace element variables, potentially relatable to magmatic compositional evolution.

Geochemistry of rare earth elements within waste rocks from the Montviel carbonatite deposit, Québec, Canada.

PubMed

Edahbi, Mohamed; Plante, Benoît; Benzaazoua, Mostafa; Pelletier, Mia

2018-04-01

Several rare earth element (REE) mine projects around the world are currently at the feasibility stage. Unfortunately, few studies have evaluated the contamination potential of REE and their effects on the environment. In this project, the waste rocks from the carbonatites within the Montviel proterozoic alkaline intrusion (near Lebel-sur-Quévillon, Quebec, Canada) are assessed in this research. The mineralization is mainly constituted by light REE (LREE) fluorocarbonates (qaqarssukite-Ce, kukharenkoite-Ce), LREE carbonates (burbankite, Sr-Ba-Ca-REE, barytocalcite, strontianite, Ba-REE-carbonates), and phosphates (apatite, monazite). The gangue minerals are biotites, chlorite, albite, ankerite, siderite, and calcite. The SEM-EDS analyses show that (i) the majority of REE are associated with the fine fraction (< 106 μm), (ii) REE are mainly associated with carbonates, (iii) all analyzed minerals preferably contain LREE (La, Ce, Pr, Nd, Sm, Eu), (iv) the sum of LREE in each analyzed mineral varies between ~ 3 and 10 wt%, (v) the heavy REE (HREE) identified are Gd and Yb at < 0.4 wt%, and (vi) three groups of carbonate minerals were observed containing variable concentrations of Ca, Na, and F. Furthermore, the mineralogical composition of REE-bearing minerals, REE mobility, and REE speciation was investigated. The leachability and geochemical behavior of these REE-bearing mine wastes were tested using normalized kinetic testing (humidity cells). Leachate results displayed higher LREE concentrations, with decreasing shale-normalized patterns. Thermodynamical equilibrium calculations suggest that the precipitation of secondary REE minerals may control the REE mobility.

Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation.

PubMed

Prudêncio, Maria Isabel; Valente, Teresa; Marques, Rosa; Sequeira Braga, Maria Amália; Pamplona, Jorge

2015-11-01

Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD. Copyright © 2015 Elsevier Ltd. All rights reserved.

Formation of the world's largest REE deposit through protracted fluxing of carbonatite by subduction-derived fluids

PubMed Central

Ling, Ming-Xing; Liu, Yu-Long; Williams, Ian S.; Teng, Fang-Zhen; Yang, Xiao-Yong; Ding, Xing; Wei, Gang-Jian; Xie, Lu-Hua; Deng, Wen-Feng; Sun, Wei-Dong

2013-01-01

Rare Earth Elements (REE) are essential to modern society but the origins of many large REE deposits remain unclear. The U-Th-Pb ages, chemical compositions and C, O and Mg isotopic compositions of Bayan Obo, the world's largest REE deposit, indicate a protracted mineralisation history with unusual chemical and isotopic features. Coexisting calcite and dolomite are in O isotope disequilibrium; some calcitic carbonatite samples show highly varied δ26Mg which increases with increasing Si and Mg; and ankerite crystals show decreases in Fe and REE from rim to centre, with highly varied REE patterns. These and many other observations are consistent with an unusual mineralisation process not previously considered; protracted fluxing of calcitic carbonatite by subduction-released high-Si fluids during the closure of the Palaeo-Asian Ocean. The fluids leached Fe and Mg from the mantle wedge and scavenged REE, Nb and Th from carbonatite, forming the deposit through metasomatism of overlying sedimentary carbonate.

Rare earth element and uranium-thorium variations in tufa deposits from the Mono Basin, CA

NASA Astrophysics Data System (ADS)

Wilcox, E. S.; Tomascak, P. B.; Hemming, N.; Hemming, S. R.; Rasbury, T.; Stine, S.; Zimmerman, S. R.

2009-12-01

Samples of fossil tufa deposits from several localities in the Mono Basin, eastern California, were analyzed for trace element concentrations in order to better understand changes in lake composition in the past. These deposits were formed during the last glacial cycle, mostly during deglaciation (Benson et al., 1990, PPP). Three elevations are represented by the analyses. Samples from near Highway 167 were sampled between 2063 and 2069 m asl. Samples from near Thompson Road were sampled between 2015 and 2021 m. One layered mound was sampled at 1955 m. Concentrations of the lanthanide rare earth elements (REE), in particular the heavy/light (HREE/LREE) distributions, have been shown to be sensitive to alkalinity in modern saline lakes (e.g., Johannesson et al., 1994, GRL, 21, 773-776), and the same has been suggested for U/Th (Anderson et al., 1982, Science, 216, 514-516). Holocene to near-modern tufa towers exist in shallow water and around the current shoreline (1945 m). Tufa towers above 2000 m include a characteristic morphology termed thinolite, interpreted to represent pseudomorphs after the very cold water mineral ikaite. Most lower elevation towers do not have the thinolite morphology, but some layered tufa mounds at low elevations include several layers of thinolite, such as the one sampled for this project. Analyses were made on millimeter-scale bulk samples from tufa towers. Measurements were made on sample solutions with a Varian 820MS quadrupole ICP-MS. Mono Basin tufa samples have total REE concentrations ranging from 0.029 to 0.77 times average shales. Samples have flat to moderately HREE-enriched shale-normalized patterns with limited overall variability ([La/Lu]SN of 1.8 to 9.6) but with some variability in the slope of the HREE portion of the patterns. Tufa towers sampled from three elevations have (Gd/Lu)SN of 0.40 to 1.5. The REE patterns of most samples have small positive Ce anomalies, but a minority of samples, all from the layered tufa mound, have small negative Ce anomalies. Concentrations of U and Th range from 0.5 to 12 ppm and from 0.2 to 12 ppm, respectively, with substantial variability in U/Th (0.08 to 20). Relative to modern Mono Lake water (Johannesson and Lyons, 1994, Limn. Oc., 39, 1141-1154) the tufa samples have 29 to 144000 times the total REE contents, but the water has HREE/LREE nearly twice as high as the most HREE-enriched fossil tufa. There is a general trend in which samples from higher elevation have lower average total REE, (Gd/Lu)SN and Th and higher average U and U/Th, the latter ranging from 0.52 in the locality at lowest elevation to 10.5 at the highest. In general the results show promise for the application of this approach to paleo-alkalinity, although analyses of modern precipitates as well as laboratory precipitation experiments are needed to fully address the processes.

Recovery and separation of rare earth elements using columns loaded with DNA-filter hybrid.

PubMed

Takahashi, Yoshio; Kondo, Kazuhiro; Miyaji, Asami; Umeo, Miyuki; Honma, Tetsuo; Asaoka, Satoshi

2012-01-01

Given that the supply of several rare earth elements (REEs) is sometimes limited, recycling REEs used in various advanced materials, such as Nd magnets, is important for realizing efficient use of REE resources. In the present work, the feasibility of using DNA for REE recovery and separation was examined, along with the identification of the binding site of REEs in DNA. In particular, a DNA-cellulose filter paper hybrid was prepared so that DNA-based materials can be used for the separation of REEs using columns loaded with DNA. N,N'-Disuccinimidyl was used as a cross-linker reagent for the fixation of DNA onto a fibrous cellulose filter. The results showed that (i) the DNA-filter hybrid has a sufficiently high affinity to adsorb REEs; (ii) the adsorption capacity was 0.182 mg/g for Nd; and (iii) the affinity of REEs for DNA was stronger for REEs with larger atomic numbers. The difference of the affinity among REEs in the third result was compared with the adsorption patterns of REEs discussed in the literature. The comparison suggests that phosphate in the DNA-filter paper hybrid was responsible for REE adsorption onto the hybrid. The results were supported by the Nd, Dy, and Lu L(III)-edge EXAFS; the REE-P shell was identified for the second neighboring atom, showing the importance of the phosphate site as REE binding sites. The difference in the affinity among REEs suggest that group separation of REEs (such as La, Ce, (Pr and Nd), (Ho, Dy, and Er), (Tb and Gd), (Sm, Eu), Tm, Yb, and Lu) is possible, although complete isolation of each REE from a solution containing all REEs may be difficult. For practical applications, Nd and Fe(III) were successfully separated from a synthetic solution of Nd magnet waste using columns loaded with the DNA-filter hybrid.

A Detailed Geochemical Study of Island Arc Crust: The Talkeetna Arc Section, South-central Alaska

NASA Astrophysics Data System (ADS)

Greene, A. R.; Debari, S. M.; Kelemen, P. B.; Clift, P. D.; Blusztajn, J.

2002-12-01

The Talkeetna arc section in south-central Alaska is recognized as the exposed upper mantle and crust of an accreted, Late Triassic to Middle Jurassic island arc. Detailed geochemical studies of layered gabbronorite from the middle and lower crust of this arc and a diverse suite of volcanic and plutonic rocks from the middle and upper crust provide crucial data for understanding arc magma evolution. We also present new data on parental magma compositions for the arc. The deepest level of the arc section consists of residual mantle and ultramafic cumulates adjacent to garnet gabbro and basal gabbronorite interlayered with pyroxenite. The middle crust is primarily layered gabbronorite, ranging from anorthosite to pyroxenite in composition, and is the most widespread plutonic lithology. The upper mid crust is a heterogenous assemblage of dioritic to tonalitic rocks mixed with gabbro and intruded by abundant mafic dikes and chilled pillows. The upper crust of the arc is comprised of volcanic rocks of the Talkeetna Formation ranging from basalt to rhyolite. Most of these volcanic rocks have evolved compositions (<5% MgO, Mg# <60) and overlap the composition of intermediate to felsic plutonic rocks (<3.5% MgO, Mg# <45). However, several chilled mafic rocks and one basalt have primitive characteristics (>8% MgO, Mg# >60). Ion microprobe analyses of clinopyroxene in mid-crustal layered gabbronorites have parallel REE patterns with positive-sloping LREE segments (La/Sm(N)=0.05-0.17; mean 0.11) and flat HREE segments (5-25xchondrite; mean 10xchondrite). Liquids in REE equilibrium with the clinopyroxene in these gabbronorite cumulates were calculated in order to constrain parental magmas. These calculated liquids(La/Sm(N)=0.77-1.83; mean 1.26) all fall within the range of dike and volcanic rock(La/Sm(N)=0.78-2.12; mean 1.23) compositions. However, three lavas out of the 44 we have analyzed show strong HREE depletion, which is not observed in any of the liquid compositions calculated from clinopyroxene in the gabbronorite samples. Three lavas have Mg# 50-63 (49-57 % SiO2) and two of these are in REE equilibrium with calculated liquids of cumulate gabbronorites. Five chilled samples (three dikes and two mafic inclusions) have Mg# 54-64 (48-52 % SiO2) and lie just below the calculated liquid REE patterns. The most primitive mafic dike (SiO2 =48.1; MgO =8.1 ; Mg# =62.0; Ni =73) represents a well-constrained potential parental magma to the gabbroic cumulates in the mid-crust of the arc, although, like the three primitive basalts, it is not in Fe/Mg equilibrium with the gabbros.The Mg# is too high. Presumably, this parent has lost Ni and MgO to fractionation of ultramafic cumulates at deeper levels of the arc. The average dike REE pattern is nearly identical to the calculated primary magma composition of DeBari and Sleep(1991) for the Talkeetna arc, as are the REE patterns for the chilled pillows. Least-squares mass-balance calculations of mid-crustal gabbronorites indicate pl + cpx + opx + mgt + amph represent the bulk of removed solids. Fractionation of these phases using the most primitive mafic dike described above as the parental composition can produce many of the more evolved volcanic rocks. Fe-Ti oxide accounts for 0.05-12.3 wt% (mean 5.92 wt%) of the sampled cumulates and amphibole represents 0.97-40.1 wt% (mean 16.4 wt%). Fractionation of the observed phases in the cumulate gabbronorite is reflected by TiO2 depletion in the volcanic and intermediate to felsic plutonic rocks of the middle and upper crust.

Reaction of seawater with fresh mid-ocean ridge gabbro creates ';atypical' REE pattern and high REE fluid fluxes: Experiments at 425 and 475 °C, 400 and 1000 bar

NASA Astrophysics Data System (ADS)

Beermann, O.; Garbe-Schönberg, D.; Holzheid, A. D.

2013-12-01

High-temperature MOR hydrothermalism significantly affects ocean chemistry. The Sisters Peak (SP) hydrothermal field at 5°S on the slow-spreading Mid-Atlantic Ridge (MAR) emanates fluids >400°C [1] that have high concentrations of H2, transition metals, and rare earth elements (REE) exhibiting ';atypical' REE pattern characterized by depletions of LREE and HREE relative to MREE and no Eu anomaly [2]. This is in contrast to the ';typical' LREE enrichment and strong positive Eu anomaly known from many MOR vent fluids observed world-wide [e.g., 3]. Besides temperature, the seawater-to-rock ratio (w/r ratio) has significant control on the fluid chemistry [e.g., 4, 5]. To understand how vent fluid REE-signatures are generated during water-rock interaction processes we reacted unaltered gabbro with natural bottom seawater at 425 °C and 400 bar and at 425 and 475 °C at 1000 bar at variable w/r (mass) ratios ranging from 0.5-10 by using cold seal pressure vessels (CSPV). The run durations varied from 3-72 h. Reacted fluids were analysed for major and trace elements by ICP-OES and ICP-MS. In our experiments, ';atypical' REE fluid pattern similar to those of SP fluids were obtained at high w/r ratio (5 and 10) that might be characteristic for focused fluid-flow along e.g., detachment faults at slow-spreading MOR [6]. In contrast, more ';typical'-like REE pattern with elevated LREE and slightly positive Eu anomalies have been reproduced at low w/r ratio (0.5-1). Results of numerical simulations imply that strong positive Eu anomalies of fluids and altered gabbro from high temperature MOR hydrothermal systems can be created by intense rock leaching processes at high w/r ratio (5-10). This suggests that hydrothermal circulation through the ocean crust creates ';typical' REE fluid pattern with strong positive Eu anomalies if seawater reacts with gabbroic host rock that has been already leached in REE at high fluid fluxes. Simulations of the temporal chemical evolution of high temperature MOR hydrothermal systems reveal that rock and fluid REE contents can rapidly decrease within several months particularly at high fluid fluxes. In contrast, the reaction with ';fresh', unaltered rock is evident from the high REE concentration of SP fluids. Both, fluid access to fresh rock and the fluid flux should therefore significantly control chemical fluxes to the ocean. Thus, high chemical fluxes can be expected in particular from early stage high-temperature MOR hydrothermal systems that are assumed to be not uncommon along the slow-spreading MAR. [1] Koschinsky A., Garbe-Schönberg D., Sander S., Schmidt K., Gennerich H.-H., and Strauss H. (2008) Geology 36, 615-618. [2] Schmidt K., Garbe-Schönberg D., Bau M., and Koschinsky A. (2010) Geochim. Cosmochim. Acta 74, 4058-4077. [3] Douville E., Bienvenu P., Charlou J. L., Donval J. P., Fouquet Y., Appriou P., and Gamo T. (1999). Geochim. Cosmochim. Acta 63, 627-643. [4] Seyfried [Jr.] W. E. and Bischoff J. L. (1977) Earth. Planet. Sci. Lett. 34, 71-77. [5] Hajash A. and Chandler G. W. (1981) Contrib. Mineral. Petrol. 78, 240-254. [6] McCaig A.M. and Harris M. (2012) Geology 40, 367-370.

The Parent Magmas of the Cumulate Eucrites: A Mass Balance Approach

NASA Technical Reports Server (NTRS)

Treiman, Allan H.

1996-01-01

The cumulate eucrite meteorites are gabbros that are related to the eucrite basalt meteorites. The eucrite basalts are relatively primitive (nearly flat REE patterns with La approx. 8-30 x CI), but the parent magmas of the cumulate eucrites have been inferred as extremely evolved (La to greater than 100 x CI). This inference has been based on mineral/magma partitioning, and on mass balance considering the cumulate eucrites as adcumulates of plagioclase + pigeonite only; both approaches have been criticized as inappropriate. Here, mass balance including magma + equilibrium pigeonite + equilibrium plagiociase is used to test a simple model for the cumulate eucrites: that they formed from known eucritic magma types, that they consisted only of magma + crystals in chemical equilibrium with the magma, and that they were closed to chemical exchange after the accumulation of crystals. This model is tested for major and Rare Earth Elements (REE). The cumulate eucrites Serra de Mage and Moore County are consistent, in both REE and major elements, with formation by this simple model from a eucrite magma with a composition similar to the Nuevo Laredo meteorite: Serra de Mage as 14% magma, 47.5% pigeonite, and 38.5% plagioclase; Moore County as 35% magma, 37.5% pigeonite, and 27.5% plagioclase. These results are insensitive to the choice of mineral/magma partition coefficients. Results for the Moama cumulate eucrite are strongly dependent on choice of partition coefficients; for one reasonable choice, Moama's composition can be modeled as 4% Nuevo Laredo magma, 60% pigeonite, and 36% plagioclase. Selection of parent magma composition relies heavily on major elements; the REE cannot uniquely indicate a parent magma among the eucrite basalts. The major element composition of Y-791195 can be fit adequately as a simple cumulate from any basaltic eucrite composition. However, Y-791195 has LREE abundances and La/Lu too low to be accommodated within the model using any basaltic eucrite composition and any reasonable partition coefficients. Postcumulus loss of incompatible elements seems possible. It is intriguing that Serra de Mage, Moore County, and Moama are consistent with the same parental magma; could they be from the same igneous body on the eucrite parent asteroid (4 Vesta)?

Mantle Water Contents Beneath the Rio Grande Rift (NM, USA): FTIR Analysis of Rio Puerco and Kilbourne Hole Peridotite Xenoliths

NASA Technical Reports Server (NTRS)

Schaffer, L. A.; Peslier, A. H.; Brandon, A.; Selverstone, J.

2015-01-01

Peridotite xenoliths from the Rio Grande Rift (RGR) are being analyzed for H (sub 2) O contents by FTIR (Fourier Transform Infrared) as well as for major and trace element compositions. Nine samples are from the Rio Puerco Volcanic Field (RP) which overlaps the central RGR and southeastern Colorado Plateau; seventeen samples are from Kilbourne Hole (KH) in the southern RGR. Spinel Cr# (Cr/(Cr+Al)) (0.08-0.46) and olivine Mg# (Mg/(Mg plus Fe)) (0.883-0.911) of all RGR samples fall within the olivine-spinel mantle array from [1], an indicator that peridotites are residues of partial melting. Pyroxene H (sub 2) O in KH correlate with bulk rock and pyroxene Al (sub 2) O (sub 3).The KH clinopyroxene rare earth element (REE) variations fit models of 0-13 percent fractional melting of a primitive upper mantle. Most KH peridotites have bulk-rock light REE depleted patterns, but five are enriched in light REEs consistent with metasomatism. Variation in H (sub 2) O content is unrelated to REE enrichment. Metasomatism is seen in RP pyroxenite xenoliths [2] and will be examined in the peridotites studied here. Olivine H (sub 2) O contents are low (less than or equal to 15 parts per million), and decrease from core to rim within grains. This is likely due to H loss during xenolith transport by the host magma [3]. Diffusion models of H suggest that mantle H (sub 2) O contents are still preserved in cores of KH olivine, but not RP olivine. The average H (sub 2) O content of Colorado Plateau clinopyroxene (670 parts per million) [4] is approximately 300 parts per million higher than RGR clinopyroxene (350 parts per million). This upholds the hypothesis that hydration-induced lithospheric melting occurred during flat-slab subduction of the Farallon plate [5]. Numerical models indicate hydration via slab fluids is possible beneath the plateau, approximately 600 kilometers from the paleo-trench, but less likely approximately 850 kilometers away beneath the rift [6].

Fate and Trophic Transfer of Rare Earth Elements in Temperate Lake Food Webs.

PubMed

Amyot, Marc; Clayden, Meredith G; MacMillan, Gwyneth A; Perron, Tania; Arscott-Gauvin, Alexandre

2017-06-06

Many mining projects targeting rare earth elements (REE) are in development in North America, but the background concentrations and trophic transfer of these elements in natural environments have not been well characterized. We sampled abiotic and food web components in 14 Canadian temperate lakes unaffected by mines to assess the natural ecosystem fate of REE. Individual REE and total REE concentrations (sum of individual element concentrations, ΣREE) were strongly related with each other throughout different components of lake food webs. Dissolved organic carbon and dissolved oxygen in the water column, as well as ΣREE in sediments, were identified as potential drivers of aqueous ΣREE. Log 10 of median bioaccumulation factors ranged from 1.3, 3.7, 4.0, and 4.4 L/kg (wet weight) for fish muscle, zooplankton, predatory invertebrates, and nonpredatory invertebrates, respectively. [ΣREE] in fish, benthic macroinvertebrates, and zooplankton declined as a function of their trophic position, as determined by functional feeding groups and isotopic signatures of nitrogen (δ 15 N), indicating that REE were subject to trophic dilution. Low concentrations of REE in freshwater fish muscle compared to their potential invertebrate prey suggest that fish fillet consumption is unlikely to be a significant source of REE to humans in areas unperturbed by mining activities. However, other fish predators (e.g., piscivorous birds and mammals) may accumulate REE from whole fish as they are more concentrated than muscle. Overall, this study provides key information on the baseline concentrations and trophic patterns for REE in freshwater temperate lakes in Quebec, Canada.

Environmental tracers for elucidating the weathering process in a phosphogypsum disposal site: Implications for restoration

NASA Astrophysics Data System (ADS)

Pérez-López, Rafael; Nieto, José M.; de la Rosa, Jesús D.; Bolívar, Juan P.

2015-10-01

This study provides geochemical data with the aim of identifying and tracing the weathering of phosphogypsum wastes stack-piled directly on salt-marshes of the Tinto River (Estuary of Huelva, SW Spain). With that purpose, different types of highly-polluted acid solutions were collected in the stack. Connection between these solutions and the estuarine environment was studied by geochemical tracers, such as rare earth elements (REE) and their North American Shale Composite (NASC)-normalized patterns and Cl/Br ratios. Phosphogypsum-related wastewaters include process water stored on the surface, pore-water contained in the phosphogypsum profile and edge outflow water emerging from inside the stack. Edge outflow waters are produced by waterlogging at the contact between phosphogypsum and the nearly impermeable marsh surface and discharge directly into the estuary. Process water shows geochemical characteristics typical of phosphate fertilizers, i.e. REE patterns with an evident enrichment of heavy-REE (HREE) with respect to middle-REE (MREE) and light-REE (LREE). By contrast, REE patterns of deeper pore-water and edge outflows are identical to those of Tinto River estuary waters, with a clear enrichment of MREE relative to LREE and HREE denoting influence of acid mine drainage. Cl/Br ratios of these solutions are very close to that of seawater, which also supports its estuarine origin. These findings clearly show that process water is not chemically connected with edge outflows through pore-waters, as was previously believed. Phosphogypsum weathering likely occurs by an upward flow of seawater from the marsh because of overpressure and permeability differences. Several recommendations are put forward in this study to route restoration actions, such as developing treatment systems to improve the quality of the edge outflow waters before discharging to the receiving environment.

The Redox Dynamics of Iron in a Seasonally Waterlogged Forest Soil (Chaux Forest, Eastern France) Traced with Rare Earth Element Distribution Patterns

NASA Astrophysics Data System (ADS)

Steinmann, M.; Floch, A. L.; Lucot, E.; Badot, P. M.

2014-12-01

The oxyhydroxides of iron are common soil minerals and known to control the availability of various major and trace elements essential for biogeochemical processes. We present a study from acidic natural forest soils, where reducing redox conditions due to seasonal waterlogging lead to the dissolution of Fe-oxyhydroxides, and to the release of Fe to soil water. In order to study in detail the mechanism of redox cycling of Fe, we used Rare Earth Element (REE) distribution patterns, because an earlier study has shown that they are a suitable tool to identify trace metal sources during soil reduction in wetland soils (Davranche et al., 2011). The REE patterns of soil leachates obtained with the modified 3-step BCR extraction scheme of Rauret et al., (1999) were compared with those of natural soil water. The adsorbed fractions (F1 leach), the reducible fraction of the deepest soil horizon H4 (F2 leach, 50-120 cm), and the oxidizable fractions of horizons H2 to H4 (F3 leachs, 24-120 cm) yielded REE patterns almost identical to soil water (see figure), showing that the REE and trace metal content of soil water was mainly derived from the F1 pool, and from the F2 and F3 pools of the clay mineral-rich deep soil horizons. In contrast, the F2 leach mobilized mainly Fe-oxyhydroxides associated with organic matter of the surface soil and yielded REE patterns significantly different from those of soil water. These results suggest that the trace metal content of soil water in hydromorphic soils is primarily controlled by the clay fraction of the deeper soil horizons and not by organic matter and related Fe-oxyhydroxides of the surface soil. Additional analyses are in progress in order to verify whether the REE and trace metals of the deeper soil horizons were directly derived from clay minerals or from associated Fe-oxyhydroxide coatings. Refs cited: Davranche et al. (2011), Chem. Geol. 284; Rauret et al. (1999), J. Environ. Monit. 1.

Reassessing the Formation of CK7 Northwest Africa (NWA) 8186

NASA Technical Reports Server (NTRS)

Srinivasan, P.; McCubbin, F. M.; Lapen, T. J.; Righter, M.; Agee, C. B.

2017-01-01

The classification of meteorites is commonly determined using isotopes, modal mineralogy, and bulk compositions [1]. Bulk rare earth elements (REEs) in meteorites are additionally utilized to understand parent body processes. Numerous authors have shown that chondritic groups exhibit REE patterns that may be attributable to their parent bodies [e.g. 2-4], and variations in abundances and concentrations of REEs may reflect early nebular processes, thermal metamorphism, and aqueous alteration on the parent body [5-6].

Rare earth elements in the sedimentary cycle - A pilot study of the first leg

NASA Technical Reports Server (NTRS)

Basu, A.; Blanchard, D. P.; Brannon, J. C.

1982-01-01

The effects of source rock composition and climate on the natural abundances of rare elements (REE) in the first leg of the sedimentary cycle are evaluated using a study with Holocene fluvia sands. The medium grained sand fraction of samples collected from first order streams exclusively draining granitic plutons in Montana (semi-arid), Georgia (humid), and South Carolina (humid) are analyzed. It is found that the REE distribution patterns (but not the total absolute abundances) of the daughter sands are very similar, despite compositional differences between parent plutons. Averages of the three areas are determined to have a La/Lu ratio of about 103, showing a depletion of heavy REE with respect to an average granite (La/Lu = 79) or the composition of North American Shales (La/Lu = 55). However, the Eu/Sm ratio in sands from these areas is about 0.22, which is very close to this ratio in North American Shales (0.21), although the overall REE distribution of these sands is not similar to that of the North American Shales in any way. It is concluded that the major rock type, but neither its minor subdivisions nor the climate, controls the REE distribution patterns in first cycle daughter sands, although the total and the parent rock-normalized abundances of REE in sands from humid areas are much lower than those in sands from arid areas.

Geochemistry of rare earth elements in Permian coals from the Huaibei Coalfield, China

USGS Publications Warehouse

Zheng, Lingyun; Liu, Gaisheng; Chou, C.-L.; Qi, C.; Zhang, Y.

2007-01-01

The rare earth elements (REEs) in coals are important because of: (a) REE patterns can be an indicator of the nature of source rocks of the mineral matter as well as sedimentary environments; (b) REEs abundance in coal may have industrial-significance. In this study, a total of thirty-four samples of Permian coal, partings, roof, and floor were collected from the Huaibei Coalfield, Anhui Province, China. Abundances of rare earth elements (REEs) and other elements in the samples were determined by inductively coupled-plasma mass spectrometry (ICP-MS) and inductively coupled-plasma atomic emission spectrometry (ICP-AES). The results show that the REEs are enriched in coals in the Huaibei Coalfield as compared with Chinese and U.S. coals and the world coal average. Coals in the Lower Shihezi Formation (No. 7, 5, and 4 Coals) and Upper Shihezi Formation (No. 3) have higher REE abundances than the coals in Shanxi Formation (No. 10). Magmatic intrusion resulted in high enrichment of REEs concentrations in No. 5 and 7 Coals. The REE abundances are positively correlated with the ash content. The mineral matter in these coals is mainly made up of clay minerals and carbonates. The REEs are positively correlated with lithophile elements including Si, Al, Ti, Fe, and Na, which are mainly distributed in clay minerals, indicating that REEs are contained mainly in clay minerals. The REE abundances in coals normalized by the ash are higher than that in partings. REEs abundances of coals cannot be accounted for by the REE content in the mineral matter, and some REEs associated with organic matter in coals. ?? 2007 Elsevier Ltd. All rights reserved.

Al-26, Pu-244, Ti-50, REE, and trace element abundances in hibonite grains from CM and CV meteorites

NASA Technical Reports Server (NTRS)

Fahey, A. J.; Mckeegan, K. D.; Zinner, E.; Goswami, J. N.

1987-01-01

Hibonites from the CM meteorites Murchison, Murray, and Cold Bokkeveld, and hibonites and Ti-rich pyroxene from the CV chondrite Allende are studied. Electron microprobe measurements of major element concentrations and track and ion probe measurements of Mg and Ti isotopic ratios, rare earth elements (REEs), and trace element abundances are analyzed. Correlations between isotopic anomalies in Ti, Al-26, Pu-244, and Mg-26(asterisk) are examined. Ti isotopic anomalies are compared with REE and trace element abundance patterns. Reasons for the lack of Al-26 in the hibonites are investigated and discussed. It is observed that there is no correlation between the Ti isotopic compositions, and the presence of Mg-26(asterisk), Pu-244, and REE and trace element patterns in individual hibonite samples. The data reveal that hibonites are not interstellar dust grains but formed on a short time scale and in localized regions of the early solar system.

Spatial variability and geochemistry of rare earth elements in soils from the largest uranium-phosphate deposit of Brazil.

PubMed

Cunha, Cleyton Saialy Medeiros; da Silva, Ygor Jacques Agra Bezerra; Escobar, Maria Eugenia Ortiz; do Nascimento, Clístenes Williams Araújo

2018-02-22

The Itataia uranium-phosphate deposit is the largest uranium reserve in Brazil. Rare earth elements (REEs) are commonly associated with phosphate deposits; however, there are no studies on the concentrations of REEs in soils of the Itataia deposit region. Thus, the objective of the research was to evaluate the concentration and spatial variability of REEs in topsoils of Itataia phosphate deposit region. In addition, the influence of soil properties on the geochemistry of REEs was investigated. Results showed that relatively high mean concentrations (mg kg -1 ) of heavy REEs (Gd 6.01; Tb 1.25; Ho 1.15; Er 4.05; Tm 0.64; Yb 4.61; Lu 0.65) were found in surface soils samples. Soil properties showed weak influence on the geochemical behavior of REEs in soils, except for the clay content. On the other hand, parent material characteristics, such as P and U, had strong influence on REEs concentrations. Spatial distribution patterns of REEs in soils are clearly associated with P and U contents. Therefore, geochemical surveys aiming at the delineation of ore-bearing zones in the region can benefit from our data. The results of this work reinforce the perspective for co-mining of P, U and REEs in this important P-U reserve.

Rare earth element geochemistry of outcrop and core samples from the Marcellus Shale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noack, Clinton W.; Jain, Jinesh C.; Stegmeier, John

In this paper, we studied the geochemistry of the rare earth elements (REE) in eleven outcrop samples and six, depth-interval samples of a core from the Marcellus Shale. The REE are classically applied analytes for investigating depositional environments and inferring geochemical processes, making them of interest as potential, naturally occurring indicators of fluid sources as well as indicators of geochemical processes in solid waste disposal. However, little is known of the REE occurrence in the Marcellus Shale or its produced waters, and this study represents one of the first, thorough characterizations of the REE in the Marcellus Shale. In thesemore » samples, the abundance of REE and the fractionation of REE profiles were correlated with different mineral components of the shale. Namely, samples with a larger clay component were inferred to have higher absolute concentrations of REE but have less distinctive patterns. Conversely, samples with larger carbonate fractions exhibited a greater degree of fractionation, albeit with lower total abundance. Further study is necessary to determine release mechanisms, as well as REE fate-and-transport, however these results have implications for future brine and solid waste management applications.« less

Rare earth element geochemistry of outcrop and core samples from the Marcellus Shale

DOE PAGES

Noack, Clinton W.; Jain, Jinesh C.; Stegmeier, John; ...

2015-06-26

In this paper, we studied the geochemistry of the rare earth elements (REE) in eleven outcrop samples and six, depth-interval samples of a core from the Marcellus Shale. The REE are classically applied analytes for investigating depositional environments and inferring geochemical processes, making them of interest as potential, naturally occurring indicators of fluid sources as well as indicators of geochemical processes in solid waste disposal. However, little is known of the REE occurrence in the Marcellus Shale or its produced waters, and this study represents one of the first, thorough characterizations of the REE in the Marcellus Shale. In thesemore » samples, the abundance of REE and the fractionation of REE profiles were correlated with different mineral components of the shale. Namely, samples with a larger clay component were inferred to have higher absolute concentrations of REE but have less distinctive patterns. Conversely, samples with larger carbonate fractions exhibited a greater degree of fractionation, albeit with lower total abundance. Further study is necessary to determine release mechanisms, as well as REE fate-and-transport, however these results have implications for future brine and solid waste management applications.« less

Timing and duration of Variscan high-pressure metamorphism in the French Massif Central: A multimethod geochronological study from the Najac Massif

NASA Astrophysics Data System (ADS)

Lotout, Caroline; Pitra, Pavel; Poujol, Marc; Anczkiewicz, Robert; Van Den Driessche, Jean

2018-05-01

Accurate dating of eclogite-facies metamorphism is of paramount importance in order to understand the tectonic evolution of an orogen. An eclogite sample from the Najac Massif (French Massif Central, Variscan belt) displays a zircon-bearing garnet-omphacite-amphibole-rutile-quartz peak assemblage. Pseudosection modeling suggests peak pressure conditions of 15-20 kbar, 560-630 °C. Eclogite-facies garnet displays Lu-enriched cores and Sm-rich rims and yields a Lu-Hf age of 382.8 ± 1.0 Ma and a Sm-Nd age of 376.7 ± 3.3 Ma. The ages are interpreted as marking the beginning of the prograde garnet growth during the initial stages of the eclogite-facies metamorphism, and the high-pressure (and temperature) peak reached by the rock, respectively. Zircon grains display chondrite-normalized REE spectra with variably negative, positive or no Eu anomalies and are characterized by either enriched or flat HREE patterns. However, they yield a well constrained in situ LA-ICP-MS U-Pb age of 385.5 ± 2.3 Ma, despite this REE pattern variability. Zr zonation in garnet, Y content in zircon and the diversity of zircon HREE spectra may suggest that zircon crystallized prior to and during incipient garnet growth on the prograde P-T path, recording the initial stages of the eclogite-facies conditions. Consequently, the zircon age of 385.5 ± 2.3 Ma, comparable within error with the Lu-Hf age obtained on garnet, is interpreted as dating the beginning of the eclogite-facies metamorphism. Accordingly, the duration of the prograde part of the eclogite-facies event is estimated at 6.1 ± 4.3 Myr. Subsequent exhumation is constrained by an apatite U-Pb age at 369 ± 13 Ma.

The Mineralogical Record of Oxygen Fugacity Variation and Alteration in Northwest Africa 8159: Evidence for Interaction Between a Mantle Derived Martian Basalt and a Crustal Component(s)

NASA Technical Reports Server (NTRS)

Shearer, Charles K.; Burger, Paul V.; Bell, Aaron S.; McCubbin, Francis M.; Agee, Carl; Simon, Justin I.; Papike, James J.

2015-01-01

A prominent geochemical feature of basaltic magmatism on Mars is the large range in initial Sr isotopic ratios (approx. 0.702 - 0.724) and initial epsilon-Nd values (approx. -10 to greater than +50). Within this range, the shergottites fall into three discreet subgroups. These subgroups have distinct bulk rock REE patterns, mineral chemistries (i.e. phosphate REE patterns, Ni, Co, V in olivine), oxygen fugacity of crystallization, and stable isotopes, such as O. In contrast, nakhlites and chassignites have depleted epsilon-Nd values (greater than or equal to +15), have REE patterns that are light REE enriched, and appear to have crystallized near the FMQ buffer. The characteristics of these various martian basalts have been linked to different reservoirs in the martian crust and mantle, and their interactions during the petrogenesis of these magmas. These observations pose interesting interpretive challenges to our understanding of the conditions of the martian mantle (e.g. oxygen fugacity) and the interaction of mantle derived magmas with the martian crust and surface. Martian meteorite NWA 8159 is a unique fine-grained augite basalt derived from a highly depleted mantle source as reflected in its initial epsilon-Nd value, contains a pronounced light REE depleted pattern, and crystallized presumably under very oxidizing conditions. Although considerably older than both shergottites and nahklites, it has been petrogenetically linked to both styles of martian magmatism. These unique characteristics of NWA 8159 may provide an additional perspective for deciphering the petrogenesis of martian basalts and the nature of the crust of Mars.

Rare earth element mobility in vesicular lava during low-grade metamorphism

NASA Astrophysics Data System (ADS)

Nyström, Jan Olov

1984-12-01

A geochemical comparison of basaltic relicts and spilitic domains from two burial metamorphosed flows in central Chile, of similar original composition and rich and poor in amygdules, respectively, demonstrates a relationship between initial vesicularity and rare earth element (REE) mobility. During spilitization the REE were partly leached from permeable parts of the flows and precipitated in voids, now amygdules and veinlets. The REE (excluding Eu) moved coherently in the highly amygdaloidal flow: spilitic domains and amygdules inherited the basaltic REE pattern. Besides being characterized by a positive Eu anomaly, epidotes separated from amygdules have a REE distribution which mimics that of the basalt; the absolute contents range widely, suggesting local and/or temporal REE variations in the metamorphic fluids. Pumpellyite differs by being strongly enriched in heavy REE. Similar ratios of Th, Hf and Ta in samples as contrasting as relict basalt and a geode are consistent with coherent leaching. Coherent mobility, when established for a rock system, can be used to elucidate, for example, whether minerals in cross-cutting veins were formed by local redistribution or from introduced material.

Rare earth element carriers in the Shergotty meteorite and implications for its chronology

NASA Technical Reports Server (NTRS)

Lundberg, Laura L.; Crozaz, Ghislaine; Zinner, Ernst; Mckay, Gordon

1988-01-01

This paper reports on the results of ion-probe measurements of REE concentrations in individual grains of the Shergotty meteorite. The phases analyzed included whitlockite, apatite, baddeleyite, augite, pigeonite, maskelynite, and K-rich glass; the whitlockite and apatite phases were also analyzed for U. Results indicate that whitlockite contains the bulk of the REE in Shergotty, with no evidence for distinct light-REE patterns in texturally different whitlockites. The results on the evolution of the REE abundances in the Shergotty late-stage interstitial melt, inferred from the analysis of whitlockite, are consistent with closed system crystallization. No metasomatic alteration is required to explain the REE data. It is concluded that there is no compelling reason to attribute chronological significance to the Sm-Nd array, as was done by Jagoutz and Waenke (1986).

Rare earth elements minimal harvest year variation facilitates robust geographical origin discrimination: The case of PDO "Fava Santorinis".

PubMed

Drivelos, Spiros A; Danezis, Georgios P; Haroutounian, Serkos A; Georgiou, Constantinos A

2016-12-15

This study examines the trace and rare earth elemental (REE) fingerprint variations of PDO (Protected Designation of Origin) "Fava Santorinis" over three consecutive harvesting years (2011-2013). Classification of samples in harvesting years was studied by performing discriminant analysis (DA), k nearest neighbours (κ-NN), partial least squares (PLS) analysis and probabilistic neural networks (PNN) using rare earth elements and trace metals determined using ICP-MS. DA performed better than κ-NN, producing 100% discrimination using trace elements and 79% using REEs. PLS was found to be superior to PNN, achieving 99% and 90% classification for trace and REEs, respectively, while PNN achieved 96% and 71% classification for trace and REEs, respectively. The information obtained using REEs did not enhance classification, indicating that REEs vary minimally per harvesting year, providing robust geographical origin discrimination. The results show that seasonal patterns can occur in the elemental composition of "Fava Santorinis", probably reflecting seasonality of climate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mineralogical Features and REE Distribution in Ortho- and Clinopyroxenes of the HaH 317 Enstatite Chondrite

NASA Astrophysics Data System (ADS)

Moggi-Cecchi, V.; Pratesi, G.

2004-03-01

SEM, EMPA and LA-ICP-MS analyses have been performed on HaH 317, an EL4 enstatite chondrite. Phases detected are En, Kam, Tro, Dio, Pla, Nin, Old. Diopside and enstatite grains display similar REEs patterns with marked Ce and LREE enrichments.

a Dual Proxy of Oceanic Weathering Inputs: Rare Earth Element Patterns and nd Isotopes from Metalliferous Sediment Cores

NASA Astrophysics Data System (ADS)

Sherrell, R. M.; Wright, J. D.; Hamelin, B.; Michard, A.

2002-12-01

Recent interest in reconstructing Nd isotopic distributions in the past ocean using Fe-Mn crusts, oxide coatings on sediment particles, foraminifera shells and fish teeth has raised questions about relative influence of water mass mixing vs. variations in weathering input. We have explored the utility of hydrothermal metalliferous sediments for generating high-resolution records of both Nd isotopes and rare earth element (REE) patterns in deepwater. We present a 135kyr record of high precision REE data, preliminary Nd isotope ratios, and δ18O from a 2.3 m core collected at 3180m at 11S on the East Pacific Rise (EPR). REEs are dominated (\\>96%) by seawater REEs adsorbed to Fe particles in these metalliferous carbonates; the hydrothermal REE source itself is negligible. Downcore variations in Nd/Er (proxy for light/heavy pattern fractionation) are not large (10%) but are easily quantified by our ICP-MS method (precision 1%), and reproducibly correspond to δ18O shifts. The largest Nd/Er excusions occur during deglaciations, e.g. Nd/Er=5.1 to 4.4 mol/mol between glacial MIS 6 and interglacial MIS 5e. If these variations reflect composition of ambient deepwater, then the results are opposite those expected by reduced influence of Atlantic component water (high Nd/Er) during glacials. Prelimininary ɛNd values for samples taken at Nd/Er extrema in MIS 1, 2, 5e and 6 are nearly invarient at -3.5+/-0.4, in excellent agreement with modern water column ɛNd for Pacific deepwater at this depth. Thus, while paleo-ɛNd shows virtually no change over 135kyr, REE pattern does carry information, but not, we believe, about water mass mixing changes. We suggest instead that Nd/Er reflects climatically-influenced weathering inputs to the Pacific REE pool. We propose a sea-level-driven mechanism: glacial low sea-stand reduces the extent of estuarine environments in which the light-REE-depleted seawater pattern is imparted, causing 1) more direct input of unfractionated crustal REE sources, and 2) release of REEs during erosion of high Nd/Er shelf sediments. This mechanism, unlike tectonically-driven shifts in weathering sources, can occur on glacial/interglacial timescales, and is expected to result in negligible change in Nd isotopic input, consistent with observations. Alternative mechanisms could involve temporal variations in the flux and composition of water column particles. In a first application to longer timescales, a low-resolution Cenozoic record from DSDP Leg 92, shows much larger but smooth variation of 50% in Nd/Er between 28 and 1.5 Ma, with high values from 28 to 20 Ma, decreasing during the mid-Miocene to values similar to modern at <8 Ma. ɛNd varies from -3 (near present deepwater value) to ~-6, but does not co-vary simply with Nd/Er. The combination of Nd/Er and ɛNd constitutes a new tandem proxy that may reveal changes in the style and/or source of weathering inputs to the past ocean, not interpretable from ɛNd alone. The results may have implications for climate-linked changes in the oceanic supply of biogeochemically important elements such as Fe and P.

A New Dual Proxy of Oceanic Weathering Inputs: Rare Earth Element Patterns and Nd Isotopes From Metalliferous Sediment Cores

NASA Astrophysics Data System (ADS)

Sherrell, R.; Wright, J.; Michard, A.; Hamelin, B.

Recent interest in reconstructing Nd isotopic distributions in the past ocean using Fe- Mn crusts, oxide coatings on sediment particles, foraminifera shells and fish teeth has raised questions about relative influence of water mass mixing vs. variations in weath- ering input. We have explored the utility of hydrothermal metalliferous sediments for generating high-resolution records of both Nd isotopes and rare earth element (REE) patterns in deepwater. We present a 135kyr record of high precision REE data, pre- liminary Nd isotope ratios, and 18O from a 2.3 m core collected at 3180m at 11S on the East Pacific Rise (EPR). REEs are dominated ( 96%) by seawater REEs adsorbed to Fe particles in these metalliferous carbonates; the hydrothermal REE source itself is negligible. Downcore variations in Nd/Er (proxy for light/heavy pattern fractiona- tion) are not large (10%) but are easily quantified by our ICP-MS method (precision 1%), and reproducibly correspond to 18O shifts. The largest Nd/Er excusions occur during deglaciations, e.g. Nd/Er=5.1 to 4.4 mol/mol between glacial MIS 6 and inter- glacial MIS 5e. If these variations reflect composition of ambient deepwater, then the results are opposite those expected by reduced influence of Atlantic component water (high Nd/Er) during glacials. Prelimininary Nd values for samples taken at Nd/Er ex- trema in MIS 1, 2, 5e and 6 are nearly invarient at -3.5+/-0.4, in excellent agreement with modern water column Nd for Pacific deepwater at this depth. Thus, while paleo- Nd shows virtually no change over 135kyr, REE pattern does carry information, but not, we believe, about water mass mixing changes. We suggest instead that Nd/Er re- flects climatically-influenced weathering inputs to the Pacific REE pool. We propose a sea-level-driven mechanism: glacial low sea-stand reduces the extent of estuarine environments in which the light-REE-depleted seawater pattern is imparted, causing 1) more direct input of unfractionated crustal REE sources, and 2) release of REEs during erosion of high Nd/Er shelf sediments. This mechanism, unlike tectonically- driven shifts in weathering sources, can occur on glacial/interglacial timescales, and is expected to result in negligible change in Nd isotopic input, consistent with ob- servations. Alternative mechanisms could involve temporal variations in the flux and composition of water column particles. In a first application to longer timescales, a low-resolution Cenozoic record from DSDP Leg 92, shows much larger but smooth variation of 50% in Nd/Er between 28 and 1.5 Ma, with high values from 28 to 20 Ma, decreasing during the mid-Miocene to values similar to modern at <8 Ma. Nd varies from -3 (near present deepwater value) to -6, but does not co-vary simply with Nd/Er. The combination of Nd/Er and Nd constitutes a new tandem proxy that may reveal changes in the style and/or source of weathering inputs to the past ocean, not interpretable from Nd alone. The results may have implications for climate-linked changes in the oceanic supply of biogeochemically important elements such as Fe and P.

Ecosystem Composition Controls the Fate of Rare Earth Elements during Incipient Soil Genesis

NASA Astrophysics Data System (ADS)

Zaharescu, Dragos G.; Burghelea, Carmen I.; Dontsova, Katerina; Presler, Jennifer K.; Maier, Raina M.; Huxman, Travis; Domanik, Kenneth J.; Hunt, Edward A.; Amistadi, Mary K.; Gaddis, Emily E.; Palacios-Menendez, Maria A.; Vaquera-Ibarra, Maria O.; Chorover, Jon

2017-02-01

The rare earth elements (REE) are increasingly important in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. However, REE distribution in early rock-microbe-plant systems has remained elusive. We tested the hypothesis that REE mass-partitioning during incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, vascular plants (Buffalo grass), and arbuscular mycorrhiza. Pore-water element abundances revealed a rapid transition from abiotic to biotic signatures of weathering, the latter associated with smaller aqueous loss and larger plant uptake. Abiotic dissolution was 39% of total denudation in plant-microbes-mycorrhiza treatment. Microbes incremented denudation, particularly in rhyolite, and this resulted in decreased bioavailable solid pools in this rock. Total mobilization (aqueous + uptake) was ten times greater in planted compared to abiotic treatments, REE masses in plant generally exceeding those in water. Larger plants increased bioavailable solid pools, consistent with enhanced soil genesis. Mycorrhiza generally had a positive effect on total mobilization. The main mechanism behind incipient REE weathering was carbonation enhanced by biotic respiration, the denudation patterns being largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate and mobilization: solid pool ratios, and in the pattern of denudation and uptake.

Rare earth element scavenging in seawater

NASA Astrophysics Data System (ADS)

Byrne, Robert H.; Kim, Ki-Hyun

1990-10-01

Examinations of rare earth element (REE) adsorption in seawater, using a variety of surface-types, indicated that, for most surfaces, light rare earth elements (LREEs) are preferentially adsorbed compared to the heavy rare earths (HREEs). Exceptions to this behavior were observed only for silica phases (glass surfaces, acid-cleaned diatomaceous earth, and synthetic SiO 2). The affinity of the rare earths for surfaces can be strongly affected by thin organic coatings. Glass surfaces which acquired an organic coating through immersion in Tampa Bay exhibited adsorptive behavior typical of organic-rich, rather than glass, surfaces. Models of rare earth distributions between seawater and carboxylate-rich surfaces indicate that scavenging processes which involve such surfaces should exhibit a strong dependence on pH and carbonate complexation. Scavenging models involving carboxylate surfaces produce relative REE abundance patterns in good general agreement with observed shale-normalized REE abundances in seawater. Scavenging by carboxylate-rich surfaces should produce HREE enrichments in seawater relative to the LREEs and may produce enrichments of lanthanum relative to its immediate trivalent neighbors. Due to the origin of distribution coefficients as a difference between REE solution complexation (which increases strongly with atomic number) and surface complexation (which apparently also increases with atomic number) the relative solution abundance patterns of the REEs produced by scavenging reactions can be quite complex.

Ecosystem Composition Controls the Fate of Rare Earth Elements during Incipient Soil Genesis

PubMed Central

Zaharescu, Dragos G.; Burghelea, Carmen I.; Dontsova, Katerina; Presler, Jennifer K.; Maier, Raina M.; Huxman, Travis; Domanik, Kenneth J.; Hunt, Edward A.; Amistadi, Mary K.; Gaddis, Emily E.; Palacios-Menendez, Maria A.; Vaquera-Ibarra, Maria O.; Chorover, Jon

2017-01-01

The rare earth elements (REE) are increasingly important in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. However, REE distribution in early rock-microbe-plant systems has remained elusive. We tested the hypothesis that REE mass-partitioning during incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, vascular plants (Buffalo grass), and arbuscular mycorrhiza. Pore-water element abundances revealed a rapid transition from abiotic to biotic signatures of weathering, the latter associated with smaller aqueous loss and larger plant uptake. Abiotic dissolution was 39% of total denudation in plant-microbes-mycorrhiza treatment. Microbes incremented denudation, particularly in rhyolite, and this resulted in decreased bioavailable solid pools in this rock. Total mobilization (aqueous + uptake) was ten times greater in planted compared to abiotic treatments, REE masses in plant generally exceeding those in water. Larger plants increased bioavailable solid pools, consistent with enhanced soil genesis. Mycorrhiza generally had a positive effect on total mobilization. The main mechanism behind incipient REE weathering was carbonation enhanced by biotic respiration, the denudation patterns being largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate and mobilization: solid pool ratios, and in the pattern of denudation and uptake. PMID:28230202

Trace elements in Gem-Quality Diamonds - Origin and evolution of diamond-forming fluid inclusions

NASA Astrophysics Data System (ADS)

Pearson, Graham; Krebs, Mandy; Stachel, Thomas; Woodland, Sarah; Chinn, Ingrid; Kong, Julie

2017-04-01

In the same way that melt inclusions in phenocrysts have expanded our idea of melt formation and evolution in basalts, studying fluids trapped in diamonds is providing important new constraints on the nature of diamond-forming fluids. Fibrous and cloudy diamonds trap a high but variable density of fluid inclusions and so have been extensively studied using major and trace element compositions. In contrast, constraining the nature of the diamond-forming fluid for high purity gem-quality diamonds has been restricted by the rarity of available high quality trace element data. This is due to the extremely low concentrations of impurities that gem diamonds contain - often in the ppt range. The recent discovery of fluids in gem diamonds showing similar major element chemistry to fluid-rich diamonds suggest that many diamonds may share a common spectrum of parental fluids. Here we test this idea further. Recent advances in analytical techniques, in particular the development of the "off-line" laser ablation pre-concentration approach, have allowed fully quantitative trace element data to be recovered from "fluid-poor", high quality gem diamonds. We present trace element data for gem diamonds from a variety of locations from Canada, S. Africa and Russia, containing either silicate or sulphide inclusions to examine possible paragenetic or genetic differences between fluids. REE abundance in the "gem" diamonds vary from 0.1 to 0.0001 x chondrite. To a first order, we observe the same spectrum of trace element compositions in the gem diamonds as that seen in fluid-rich "fibrous" diamonds, supporting a common origin for the fluids. REE patterns range from extremely flat (Ce/Yb)n 2.5 to 5 (commonly in sulphide-bearing diamonds) to >70, the latter having significantly greater inter-element HFSE/LILE fractionation. In general, the fluids from the sulphide-bearing diamonds are less REE-enriched than the silicate-bearing diamonds, but the ranges overlap significantly. The very large range in REE fractionation mimics very closely that produced in high pressure (5-6 GPa) experimental melts of CO2-H2O fluxed peridotite. Hence, the elemental characteristics of the fluids could be reconciled by the diamonds growing from such melts over a range of T and hence F, with the sulphide-bearing diamonds generally being produced by larger fraction (higher T) melts that have reacted less with their wall rocks. It is also possible that the less REE enriched fluids are consistent with derivation from more reduced CH4-bearing fluids that have lower solute capacity than oxidised fluids. This option is being evaluated.

Ion-adsorption REEs in regolith of the Liberty Hill pluton, South Carolina, USA: An effect of hydrothermal alteration

USGS Publications Warehouse

Bern, Carleton R.; Yesavage, Tiffany; Foley, Nora K.

2017-01-01

Ion-adsorbed rare earth element (REE) deposits supply the majority of world heavy REE production and substantial light REE production, but relatively little is known of their occurrence outside Southeast Asia. We examined the distribution and forms of REEs on a North American pluton located in the highly weathered and slowly eroding South Carolina Piedmont. The Hercynian Liberty Hill pluton experiences a modern climate that includes ~ 1500 mm annual rainfall and a mean annual temperature of 17 °C. The pluton is medium- to coarse-grained biotite-amphibole granite with minor biotite granite facies. REE-bearing phases are diverse and include monazite, zircon, titanite, allanite, apatite and bastnäsite. Weathered profiles were sampled up to 7 m-deep across the ~ 400 km2 pluton. In one profile, ion-adsorbed REEs plus yttrium (REE + Y) ranged up to 581 mg/kg and accounted for up to 77% of total REE + Y in saprolite. In other profiles, ion-adsorbed REE + Y ranged 12–194 mg/kg and only accounted for 3–37% of totals. The profile most enriched in ion-adsorbed REEs was located along the mapped boundary of two granite facies and contained trioctahedral smectite in the saprolite, evidence suggestive of hydrothermal alteration of biotite at that location. Post-emplacement deuteric alteration can generate easily weathered REE phases, particularly fluorocarbonates. In the case of Liberty Hill, hydrothermal alteration may have converted less soluble to more soluble REE minerals. Additionally, regolith P content was inversely correlated with the fraction ion-adsorbed REEs, and weathering related secondary REE-phosphates were found in some regolith profiles. Both patterns illustrate how low P content aids in the accumulation of ion-adsorbed REEs. The localized occurrence at Liberty Hill sheds light on conditions and processes that generate ion-adsorbed REEs.

Rare earth element contents of the Lusi mud: An attempt to identify the environmental origin of the hot mudflow in East Java - Indonesia

NASA Astrophysics Data System (ADS)

Agustawijaya, Didi Supriadi; Karyadi, Karyadi; Krisnayanti, Baiq Dewi; Sutanto, Sutanto

2017-12-01

The Sidoarjo mudflow in East Java, Indonesia, has been erupting since May 29th, 2006. The eruption has been known as the Lusi (lumpur Sidoarjo), which was previously considered as a remote seismic event consequence, but current geyser-like activities show an association with a geothermal phenomenon. A method of characterizing rare earth elements (REE) is commonly an effective tool for recognizing a geothermal system, and here it is adapted to particularly indicate the environmental origin of the Lusi mud. Results show that the Lusi hot mud is made of a porous smectite structure of a shale rock type, which becomes an ideal tank for trapping the REE, especially the light REE. Volcanic activities seem to be an important influence in the eruption; however, since there is a lack of significant isotopic evidences in the mobilization of the REE during the eruption, the chloride neutral pH water of the Lusi may hardly contain the REE. The moderate Ce and Eu anomalies found in the REE patterns of the mud strongly indicate a sea-floor basin as the most probable environment for the REE fractionation during the sedimentary rock formation, in which the weathering processes of volcanic rock origin enriched the Lusi shale with the REE.

An investigation into heterogeneity in a single vein-type uranium ore deposit: Implications for nuclear forensics.

PubMed

Keatley, A C; Scott, T B; Davis, S; Jones, C P; Turner, P

2015-12-01

Minor element composition and rare earth element (REE) concentrations in nuclear materials are important as they are used within the field of nuclear forensics as an indicator of sample origin. However recent studies into uranium ores and uranium ore concentrates (UOCs) have shown significant elemental and isotopic heterogeneity from a single mine site such that some sites have shown higher variation within the mine site than that seen between multiple sites. The elemental composition of both uranium and gangue minerals within ore samples taken along a single mineral vein in South West England have been measured and reported here. The analysis of the samples was undertaken to determine the extent of the localised variation in key elements. Energy Dispersive X-ray spectroscopy (EDS) was used to analyse the gangue mineralogy and measure major element composition. Minor element composition and rare earth element (REE) concentrations were measured by Electron Probe Microanalysis (EPMA). The results confirm that a number of key elements, REE concentrations and patterns used for origin location do show significant variation within mine. Furthermore significant variation is also visible on a meter scale. In addition three separate uranium phases were identified within the vein which indicates multiple uranium mineralisation events. In light of these localised elemental variations it is recommended that representative sampling for an area is undertaken prior to establishing the REE pattern that may be used to identify the originating mine for an unknown ore sample and prior to investigating impact of ore processing on any arising REE patterns. Copyright © 2015 Elsevier Ltd. All rights reserved.

The assessment of REE patterns and 143Nd/ 144Nd ratios in fish remains

NASA Astrophysics Data System (ADS)

Grandjean, Patricia; Cappetta, Henri; Michard, Annie; Albarède, Francis

1987-07-01

The REE content and isotopic composition of Sr and Nd have been determined in fish teeth ranging in age from the Trias to the present and from various localities mostly around the Atlantic. These measurements have been carried out on Selachian and Teleost remains from the same locality in Togo and show no appreciable difference, which suggests, with the help of a mass balance calculation of the Ce anomaly, that diagenetic effects are not responsible for the REE enrichment of biogenic phosphates. One group of fossil teeth has about 3 times the REE abundances of shale and a shale-normalized pattern with a minimum at Sm: it is thought to reflect deposition in the open-sea environment. A second group has REE concentration about 10 times higher than the first group with either a regular light REE enrichment or, more frequently, a maximum in the middle REE, both being probably indicative of deposition in estuarine or near-shore conditions. The shape of the REE spectra and the size of the Ce anomaly can be used semi-quantitatively to determine the depth of deposition. The results presented here on Late Cretaceous/Eocene fish teeth samples from Morocco reflect an increasing influx of deep waters with a lowLa/Yb ratio and strong negative Ce anomaly, which agrees well with the evolution of sediment chemistry and microfauna associations. In contrast, ɛ Nd is typical of the water mass in which the fish debris decayed. Examples of nearly isolated basins identified with Nd isotopes include the South Atlantic prior to the Lutetian (ɛ Nd ≈ -13.5), the Miocene Persian Gulf (ɛ Nd = -3.1), and Bolivia during the Late Cretaceous (ɛ Nd = -12.8). Togo and Guinea-Bissau results suggest that, in the South Atlantic, the meridional oceanic circulation had not started before 45 Ma ago. Combination of REE andɛ Nd data suggests that the assignment of Jurassic-Cretaceous samples measured so far to open-sea water masses is still ambiguous.

Rare earth elements (REE) and yttrium in stream waters, stream sediments, and Fe Mn oxyhydroxides: Fractionation, speciation, and controls over REE + Y patterns in the surface environment

NASA Astrophysics Data System (ADS)

Leybourne, Matthew I.; Johannesson, Karen H.

2008-12-01

We have collected ˜500 stream waters and associated bed-load sediments over an ˜400 km 2 region of Eastern Canada and analyzed these samples for Fe, Mn, and the rare earth elements (REE + Y). In addition to analyzing the stream sediments by total digestion (multi-acid dissolution with metaborate fusion), we also leached the sediments with 0.25 M hydroxylamine hydrochloride (in 0.05 M HCl), to determine the REE + Y associated with amorphous Fe- and Mn-oxyhydroxide phases. We are thus able to partition the REE into "dissolved" (<0.45 μm), labile (hydroxylamine) and detrital sediment fractions to investigate REE fractionation, and in particular, with respect to the development of Ce and Eu anomalies in oxygenated surface environments. Surface waters are typically LREE depleted ([La/Sm] NASC ranges from 0.16 to 5.84, average = 0.604, n = 410; where the REE are normalized to the North America Shale Composite), have strongly negative Ce anomalies ([Ce/Ce ∗] NASC ranges from 0.02 to 1.25, average = 0.277, n = 354), and commonly have positive Eu anomalies ([Eu/Eu ∗] NASC ranges from 0.295 to 1.77, average = 0.764, n = 84). In contrast, the total sediment have flatter REE + Y patterns relative to NASC ([La/Sm] NASC ranges from 0.352 to 1.12, average = 0.778, n = 451) and are slightly middle REE enriched ([Gd/Yb] NASC ranges from 0.55 to 3.75, average = 1.42). Most total sediments have negative Ce and Eu anomalies ([Ce/Ce ∗] NASC ranges from 0.097 to 2.12, average = 0.799 and [Eu/Eu ∗] NASC ranges from 0.39 to 1.43, average = 0.802). The partial extraction sediments are commonly less LREE depleted than the total sediments ([La/Sm] NASC ranges from 0.24 to 3.31, average = 0.901, n = 4537), more MREE enriched ([Gd/Yb] NASC ranges from 0.765 to 6.28, average = 1.97) and Ce and Eu anomalies (negative and positive) are more pronounced. The partial extraction recovered, on average ˜20% of the Fe in the total sediment, ˜80% of the Mn, and 21-29% of the REEs (Ce = 19% and Y = 32%). Comparison between REEs in water, partial extraction and total sediment analyses indicates that REEs + Y in the stream sediments have two primary sources, the host lithologies (i.e., mechanical dispersion) and hydromorphically transported (the labile fraction). Furthermore, Eu appears to be more mobile than the other REE, whereas Ce is preferentially removed from solution and accumulates in the stream sediments in a less labile form than the other REEs + Y. Despite poor statistical correlations between the REEs + Y and Mn in either the total sediment or partial extractions, based on apparent distribution coefficients and the pH of the stream waters, we suggest that either sediment organic matter and/or possibly δ-MnO 2/FeOOH are likely the predominant sinks for Ce, and to a lesser extent the other REE, in the stream sediments.

Rare earth elements mobility processes in an AMD-affected estuary: Huelva Estuary (SW Spain).

PubMed

Lecomte, K L; Sarmiento, A M; Borrego, J; Nieto, J M

2017-08-15

Huelva Estuary is a transition zone where REE-rich acidic waters interact with saline-alkaline seawater. This mixing process influences the geochemical and mineralogical characteristics of particulate and dissolved fractions. The Tinto River has >11,000μgL -1 dissolved REE (pH=1.66), whereas seawater only reaches 8.75·10 -2 μgL -1 dissolved REE (pH=7.87). REE-normalized patterns in "pH<6 solutions" are parallel and show similarities, diminishing their concentration as pH increases. Sequential extraction performed on the generated precipitates of mixed solutions indicates that most REE are associated to the residual phase. In a second order, REE are associated with soluble salts at pH3 and 3.5 whereas in sediments generated at pH4 and 5, they are distributed in salts (1° extraction), poorly crystallized Fe-bearing minerals (schwertmannite, 3° extraction) and well crystallized Fe-bearing minerals (goethite - hematite, 4° extraction). Finally, precipitated REE are highest at pH6 newly formed minerals with a release to solution in higher pH. Copyright © 2017 Elsevier Ltd. All rights reserved.

Garnet clinopyroxenite layers from the mantle sequences of the Northern Apennine ophiolites (Italy): Evidence for recycling of crustal material

NASA Astrophysics Data System (ADS)

Montanini, A.; Tribuzio, R.; Thirlwall, M.

2012-10-01

This study aims to define the origin of garnet clinopyroxenite layers from the mantle sequences of the External Ligurian ophiolites. These mantle sequences retain a subcontinental origin and were exposed at a Jurassic ocean-continent transition. The garnet clinopyroxenites are mafic rocks with Mg# values of 66-71. Their chondrite-normalised REE patterns are characterised by severe LREE depletion (CeN/SmN=0.1-0.2) and nearly flat (Type-A pyroxenites) to moderately enriched HREE (Type-B pyroxenites). In addition, Type-A pyroxenites display a small positive Eu anomaly. The whole-rock REE variations are paralleled by the garnet REE compositions. We attribute the major and trace element characteristics of the garnet clinopyroxenites to recycling of gabbroic protoliths that underwent partial melting under eclogite facies conditions. The garnet clinopyroxenites may represent variably evolved garnet+clinopyroxene cumulates formed by eclogite-derived melts. In an alternative hypothesis, Type-A and -B pyroxenites are residual rocks after eclogite melting and cumulates derived from the eclogite melts, respectively. The high pressure fractionation event that gave rise to the garnet clinopyroxenites is considered of Triassic age on the basis of Sm-Nd and Lu-Hf isotope correlations. The Nd-Hf isotopic compositions of the garnet clinopyroxenites in the Triassic (ɛNd=+4.7 to +7.6, ɛHf=+4.4 to +12.8) lie below the mantle array, in agreement with recycled ancient MOR-type material. The oxygen isotopic composition of garnet and clinopyroxene from the garnet clinopyroxenites (δ18O=+4.9‰ to +5.2‰) may be reconciled with subduction-related recycling of the lowermost oceanic crust, or delamination and foundering of underplated gabbros from the continental lithosphere. The potential involvement of the garnet clinopyroxenites in the melting processes that gave rise to the MOR-type oceanic crust in the Jurassic would account for the moderate Nd isotope variability and the garnet geochemical signature of the ophiolitic basalts.

Water content in the SW USA mantle lithosphere: FTIR analysis of Dish Hill and Kilbourne Hole pyroxenites

NASA Astrophysics Data System (ADS)

Gibler, R.; Peslier, A. H.; Schaffer, L. A.; Brandon, A. D.

2014-12-01

Kilbourne Hole (NM, USA) and Dish Hill (CA, USA) mantle xenoliths sample continental mantle in two different tectonic settings. Kilbourne Hole (KH) is located in the Rio Grande rift. Dish Hill (DH) is located in the southern Mojave province, an area potentially affected by subduction of the Farallon plate beneath North America [1]. FTIR analyses were obtained on well characterized pyroxenite, dunite and wehrlite xenoliths, thought to represent crystallized melts at mantle depths. PUM normalized REE patterns of the KH bulk-rocks are slightly LREE enriched and consistent with those of liquids generated by < 5% melting of a spinel peridotite source [2]. Clinopyroxenes contain from 272 to 313 ppm weight H2O similar to the lower limit of KH peridotite clinopyroxenes (250-530 ppm H2O, [3]). This is unexpected as crystallized melts like pyroxenites should concentrate water more than residual mantle-like peridotites, given that H is incompatible. PUM normalized bulk REE of the DH pyroxenites are characterized by flat to LREE depleted REE profiles consistent with > 6% melting of a spinel peridotite source. Pyroxenite pyroxenes have no detectable water but one DH wehrlite, which bulk-rock is LREE enriched, has 4 ppm H2O in orthopyroxene and <1ppm in clinopyroxene. The DH pyroxenites may thus come from a dry mantle source, potentially unaffected by the subduction of the Farallon plate. These water-poor melts either originated from shallow oceanic lithosphere overlaying the Farallon slab [4] or from continental mantle formed > 2 Ga [5]. The Farallon subduction appears to have enriched in water the southwestern United States lithospheric mantle further east than DH, beneath the Colorado plateau [6]. [1] Atwater, 1970 Tectonophysics 31, 145-165. [2] Shaw, 2000 CM 38, 1041-1064. [3] Schaffer et al, 2013 AGU Fall Meeting. [4] Luffi et al, 2009 JGR 114, 1-36. [5] Armytage et al, 2013 GCA 137, 113-133. [6] Li et al, 2008 JGR 113, 1-22.

Iridium anomalies and fractionated siderophile element patterns in impact ejecta, Brockman Iron Formation, Hamersley Basin, Western Australia: evidence for a major asteroid impact in simatic crustal regions of the early Proterozoic earth

NASA Astrophysics Data System (ADS)

Glikson, Andrew; Allen, Charlotte

2004-04-01

A stratigraphically consistent <20-cm-thick unit of microkrystite spherule and microtektite-bearing impact fallout ejecta overlying volcanic tuff of the 4th Shale Macroband (DGS4) of the Dales Gorge Member (2.47-2.50 Ga), Brockman Iron Formation, Hamersley Group, Western Australia, displays anomalous platinum group element (PGE) and other trace metal patterns. The unit has high Ir (13 ppb) and Pt (35 ppb), and low Pd (2.7 ppb) and Au (1.55-1.88 ppb). The low Pd/Ir ratios and low Cr/V suggest depletion in volatile PGE and metals relative to refractory PGE and V, contrasted to the ubiquitous high Pd/Ir of most terrestrial rocks. Marked depletion in the volatile Rare Earth Element (REE) abundances in stilpnomelane spherule cores is consistent with this model. The loss of volatile PGE, analogous to relations in 3.24 Ga impact fallout units of the Barberton greenstone belt (S3 and S4), suggests fractionation related to atmospheric spherule condensation. The microkrystite spherule unit locally incorporate fragments and up to meter-scale boulders of banded chert and stromatolite carbonate, suggesting tsunami transport postdating spherule deposition. DGS4 microkrystite spherules are dominated by stilpnomelane mantled by K-feldspar shells, which consist of inward-radiating fibrous feldspar aggregates suggestive of devitrification. The K and REE enrichment of spherule margins are contrasted to flat REE patterns of the stilpnomelane cores, suggesting adsorption of lithophile elements during settling of the spherules through the hydrosphere. K-feldspar shells contain submicron-scale Ni metal, oxide, sulfide and arsenide grains and euhedral needles of feldspar-exsolved ilmenite. Associated magnetite may have high nickel (<1.25% NiO). The generally mafic composition of the spherules and high Ni/Cr and Ni/Co are consistent with a target mafic-ultramafic crust, consistent with the lack of shock-metamorphosed quartz. Mixing calculations suggest a contribution of 2.5-3% projectile component to the impact-generated volatile cloud. Conservative mass balance estimates derived from the Ir and Pt flux, assuming global extent of a 10-cm-thick spherule unit and chondritic projectile composition, suggest an asteroid diameter on the scale of ˜30 km. Similar estimates are obtained from spherule sizes, which in DGS4 reach a mean diameter of ˜2.0 mm in aerodynamically elongate spherules. The evidence implies formation of an impact basin on the scale of 400 km in simatic/oceanic regions of the early Proterozoic crust.

Neodymium isotopic study of rare earth element sources and mobility in hydrothermal Fe-oxide (Fe-P-REE) systems

NASA Astrophysics Data System (ADS)

Gleason, James D.; Marikos, Mark A.; Barton, Mark D.; Johnson, David A.

2000-03-01

Rare earth element (REE)-enriched, igneous-related hydrothermal Fe-oxide hosted (Fe-P-REE) systems from four areas in North America have been analyzed for their neodymium isotopic composition to constrain REE sources and mobility in these systems. The Nd isotopic results evidence a common pattern of REE concentration from igneous sources despite large differences in age (Proterozoic to Tertiary), tectonic setting (subduction vs. intraplate), and magmatic style (mafic vs. felsic). In the Middle Proterozoic St. Francois Mountains terrane of southeastern Missouri, ɛ Nd for Fe-P-REE (apatite, monazite, xenotime) deposits ranges from +3.5 to +5.1, similar to associated felsic to intermediate igneous rocks of the same age (ɛ Nd = +2.6 to +6.2). At the mid-Jurassic Humboldt mafic complex in western Nevada, ɛ Nd for Fe-P-REE (apatite) mineralization varies between +1.1 and +2.4, similar to associated mafic igneous rocks (-1.0 to +3.5). In the nearby Cortez Mountains in central Nevada, mid-Jurassic felsic volcanic and plutonic rocks (ɛ Nd = -2.0 to -4.4) are associated with Fe-P-REE (apatite-monazite) mineralization having similar ɛ Nd (-1.7 to -2.4). At Cerro de Mercado, Durango, Mexico, all assemblages analyzed in this Tertiary rhyolite-hosted Fe oxide deposit have identical isotopic compositions with ɛ Nd = -2.5. These data are consistent with coeval igneous host rocks being the primary source of REE in all four regions, and are inconsistent with a significant contribution of REE from other sources. Interpretations of the origin of these hydrothermal systems and their concomitant REE mobility must account for nonspecialized igneous sources and varied tectonic settings.

Neodymium isotopic study of rare earth element sources and mobility in hydrothermal Fe oxide (Fe-P-REE) systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gleason, J.D.; Marikos, M.A.; Barton, M.D.

2000-03-01

Rare earth element (REE)-enriched, igneous-related hydrothermal Fe-oxide hosted (Fe-P-REE) systems from four areas in North America have been analyzed for their neodymium iosotopic composition to constrain REE sources and mobility in these systems. The Nd isotopic results evidence a common pattern of REE concentration from igneous sources despite large differences in age (Proterozoic to Tertiary), tectonic setting (subduction vs. intraplate), and magmatic style (mafic vs. felsic). In the Middle Proterozoic St. Francois Mountains terrane of southeastern Missouri, {epsilon}{sub Nd} for Fe-P-REE (apatite, monazite, xenotime) deposits ranges from +3.5 to +5.1, similar to associated felsic to intermediate igneous rocks of themore » same age ({epsilon}{sub Nd} = +2.6 to +6.2). At the mid-Jurassic Humboldt mafic complex in western Nevada, {epsilon}{sub Nd} for Fe-P-REE (apatite) mineralization varies between +1.1 and +2.4, similar to associated mafic igneous rocks ({minus}1.0 to +3.5). In the nearby Cortez Mountains in central Nevada, mid-Jurassic felsic volcanic and plutonic rocks ({epsilon}{sub Nd} = {minus}2.0 to {minus}4.4) are associated with Fe-P-REE (apatite-monazite) mineralization having similar {epsilon}{sub Nd}({minus}1.7 to {minus}2.4). At Cerro de Mercado, Durango, Mexico, all assemblages analyzed in this Tertiary rhyolite-hosted Fe oxide deposit have identical isotopic compositions with {epsilon}{sub Nd} = {minus}2.5. These data are consistent with coeval igneous host rocks being the primary source of REE in all four regions, and are inconsistent with a significant contribution of REE from other sources. Interpretations of the origin of these hydrothermal systems and their concomitant REE mobility must account for nonspecialized igneous sources and varied tectonic settings.« less

Rare Earth Element Partitioning in Lunar Minerals: An Experimental Study

NASA Technical Reports Server (NTRS)

McIntosh, E. C.; Rapp, J. F.; Draper, D. S.

2016-01-01

The partitioning behavior of rare earth elements (REE) between minerals and melts is widely used to interpret the petrogenesis and geologic context of terrestrial and extra-terrestrial samples. REE are important tools for modelling the evolution of the lunar interior. The ubiquitous negative Eu anomaly in lunar basalts is one of the main lines of evidence to support the lunar magma ocean (LMO) hypothesis, by which the plagioclase-rich lunar highlands were formed as a flotation crust during differentiation of a global-scale magma ocean. The separation of plagioclase from the mafic cumulates is thought to be the source of the Eu depletion, as Eu is very compatible in plagioclase. Lunar basalts and volcanic glasses are commonly depleted in light REEs (LREE), and more enriched in heavy REEs (HREE). However, there is very little experimental data available on REE partitioning between lunar minerals and melts. In order to interpret the source of these distinctive REE patterns, and to model lunar petrogenetic processes, REE partition coefficients (D) between lunar minerals and melts are needed at conditions relevant to lunar processes. New data on D(sub REE) for plagioclase, and pyroxenes are now available, but there is limited available data for olivine/melt D(sub REE), particularly at pressures higher than 1 bar, and in Fe-rich and reduced compositions - all conditions relevant to the lunar mantle. Based on terrestrial data, REE are highly incompatible in olivine (i.e. D much less than 1), however olivine is the predominant mineral in the lunar interior, so it is important to understand whether it is capable of storing even small amounts of REE, and how the REEs might be fractionatied, in order to understand the trace element budget of the lunar interior. This abstract presents results from high-pressure and temperature experiments investigating REE partitioning between olivine and melt in a composition relevant to lunar magmatism.

The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin

USGS Publications Warehouse

Kim, Ji-Hoon; Torres, Marta E.; Haley, Brian A.; Kastner, Miriam; Pohlman, John W.; Riedel, Michael; Lee, Young-Joo

2012-01-01

Analytical challenges in obtaining high quality measurements of rare earth elements (REEs) from small pore fluid volumes have limited the application of REEs as deep fluid geochemical tracers. Using a recently developed analytical technique, we analyzed REEs from pore fluids collected from Sites U1325 and U1329, drilled on the northern Cascadia margin during the Integrated Ocean Drilling Program (IODP) Expedition 311, to investigate the REE behavior during diagenesis and their utility as tracers of deep fluid migration. These sites were selected because they represent contrasting settings on an accretionary margin: a ponded basin at the toe of the margin, and the landward Tofino Basin near the shelf's edge. REE concentrations of pore fluid in the methanogenic zone at Sites U1325 and U1329 correlate positively with concentrations of dissolved organic carbon (DOC) and alkalinity. Fractionations across the REE series are driven by preferential complexation of the heavy REEs. Simultaneous enrichment of diagenetic indicators (DOC and alkalinity) and of REEs (in particular the heavy elements Ho to Lu), suggests that the heavy REEs are released during particulate organic carbon (POC) degradation and are subsequently chelated by DOC. REE concentrations are greater at Site U1325, a site where shorter residence times of POC in sulfate-bearing redox zones may enhance REE burial efficiency within sulfidic and methanogenic sediment zones where REE release ensues. Cross-plots of La concentrations versus Cl, Li and Sr delineate a distinct field for the deep fluids (z > 75 mbsf) at Site U1329, and indicate the presence of a fluid not observed at the other sites drilled on the Cascadia margin. Changes in REE patterns, the presence of a positive Eu anomaly, and other available geochemical data for this site suggest a complex hydrology and possible interaction with the igneous Crescent Terrane, located east of the drilled transect.

Nd-Sr isotopic and geochemical systematics in Cambrian boninites and tholeiites from Victoria, Australia

NASA Astrophysics Data System (ADS)

Nelson, D. R.; Crawford, A. J.; McCulloch, M. T.

1984-11-01

Rocks with boninitic affinities have been recognised in a number of “ophiolites”, including the Cambrian Heathcote and Mt Wellington Greenstone Belts of Victoria. Boninites and high-Mg andesites from the Heathcote Greenstone Belt show a restricted range of initial ɛ Nd values of between +3.3 to +5.8. Extremely refractory boninites from the Mt Wellington Greenstone Belt have ɛ Nd ranging from +1.3 to -9. Ti/Zr is positively correlated with Sm/Nd with the Heathcote lavas generally possessing greater depletion of Ti and enrichment of Zr relative to the middle and heavy REE with increasing LREE/HREE. These data are consistent with the generation of boninites by partial melting of refractory peridotite following invasion by LREE- and Zr-enriched, low ɛ Nd fluids. Tholeiites overlying the boninites in both greenstone belts have flat REE patterns and ɛ Nd˜+5, lower than that anticipated for lavas derived from depleted MORB source reservoirs in the Cambrian, suggesting that their source was also contaminated by a LREE-enriched, low ɛ Nd component similar to that involved in the generation of the Howqua boninites. The added components have characteristics compatible with their derivation from subducted altered oceanic crust and/or from wet subducted sediments. The identification of boninites and other low-Ti lavas in the Victorian greenstone belts is strong evidence for island arc development in southeastern Australia during the Lower Cambrian and provides further support for a subduction-related origin for many ophiolites.

Using rare earth elements for the identification of the geographic origin of food

NASA Astrophysics Data System (ADS)

Meisel, T.; Bandoniene, D.; Joebstl, D.

2009-04-01

The European Union defined regimes within the Protected Geographical Status (PGS) framework to protect names of regional food specialities. Thus only food produced in a specific geographical area with a specific way of production or quality can be protected by a protected geographical indication (PGI) label. As such Styrian Pumpkin Seed Oil has been approved with this label, but as with many other high priced regional specialities, fraud cannot be excluded or nor identified. Thus the aim of this work is, to develop an analytical method for the control of the geographic origin of pumpkin seed oil and also to test the method for other protected products. The development of such a method is not only of interest for scientists, but also of importance for the consumer wanting to know the origin of the food products and the assurance of the purity and quality. The group of rare earth elements (REE) in plants also have a characteristic distribution pattern similar to upper crustal REE distributions. Since the REE concentrations are extremely low in pumpkin seed oil (ppt to low ppb), ICP-MS was the only sensitive tool able to produce validated results. The carrier of the REE are most likely small particles distributed within the pumpkin seed oil. Unlike, e.g., olive oil, pumpkin seed oil is bottled and sold unfiltered, which makes this Styrian speciality an interesting sampling target. As pumpkin seed oils from different geographic origin show variable trace element and rare earth distribution patterns, is should possible to trace the origin of these oils. In the current project pumpkin seeds from different regions in Austria and from abroad were sampled. The trace element patterns in the extracted oil of these seeds were determined and a preliminary classification with discriminate analysis was successfully done on a statistical basis. In addition to the study of the geographic origin it was demonstrated that REE distribution patterns can also be used for the identification of adulteration of high priced pumpkin seed oil with cheap neutral tasting refined oils. Interestingly enough, the variations of the REE patterns between oils from different regions are much more pronounced than their host soils. Thus we assume that microbiological processes in the rhizosphere are in control of the REE uptake into the plant. Regional variations of the microbiological composition of the soils and probably not only a priori the bulk soil composition of the minerals in the soil are the cause of the regional variations making it possible to identify the geographic origin of pumpkin seeds and as a consequence the pumpkin seed oil.

Geochemistry and tectonic setting of the Paleoproterozoic metavolcanic rocks from the Chirano Gold District, Sefwi belt, Ghana

NASA Astrophysics Data System (ADS)

Senyah, Gloria A.; Dampare, Samuel B.; Asiedu, Daniel K.

2016-10-01

Major and trace elements, including rare earth elements (REEs) data are presented for metavolcanic rocks of the Paleoproterozoic Birimian Sefwi belt to determine the geochemical characteristics as well as the possible tectonic setting of emplacement of these rocks. In order to accomplish the aim of the study, the petrographical characteristics of the rocks were examined coupled with analysis of the rocks for their whole-rock major and trace elements contents by ICP-AES and ICP-MS methods respectively. The rocks have been classified as basalt/basaltic andesites and dolerites based on their textural and mineralogical compositions. It is observed that the rocks have suffered various degrees of alteration evident in the overprinting of primary minerals such as pyroxenes and plagioclase by chlorite, epidote, sericite and others. Generally, the rocks are moderately deformed and may have experienced at least greenschist metamorphism. The basalt/basaltic andesites are derivative magmas [Mg# (20-51), Cr (10-220 ppm) and Ni (5-137 ppm)], and show flat REE to fractionated REE patterns with (La/Sm)N = 1.36-3.90, (La/Yb)N = 1.17-5.32 and strong negative to non-existent Eu anomalies (Eu/Eu* = 0.51-1.03). N-MORB-normalised multi-element diagrams show that the rocks have geochemical patterns characterised by enrichment in LILE relative to HFSE and in LREE relative to HREE. The basalt/basaltic andesites exhibit characteristics of subduction zone-related magmas, such as pronounced negative Nb-Ta anomalies, slightly negative Hf and variable negative Ti anomalies. The dolerites do not vary much from the basalts and basaltic andesites. The MgO and Fe2O3 values of the dolerite range from 2.97 to 6.93 and 5.98 to 14.35 wt.% respectively, corresponding to Mg#s of 38-62. LREEs enrichment over HREEs with (La/Sm)N ranging from 0.61 to 4.61 and (Gd/Yb)N ranging from 0.99 to 2.91 is also typical of these rocks. The dolerites also exhibit quite invariable Eu anomalies (Eu/Eu* = 0.81-1.00) and display a pronounced Nb-Ta trough and a minor negative Ti anomaly, suggesting arc characteristics. The metavolcanic rocks from the study area generally exhibit subduction-related setting characteristics with evidence of a sub-lithospheric contamination.

Mantle water contents beneath the Rio Grande Rift (NM, USA): FTIR analysis of Rio Puerco and Kilbourne Hole peridotite xenoliths

NASA Astrophysics Data System (ADS)

Schaffer, L. A.; Peslier, A. H.; Brandon, A. D.; Selverstone, J.

2015-12-01

Peridotite xenoliths from the Rio Grande Rift (RGR) are being analyzed for H2O contents by FTIR as well as for major and trace element compositions. Nine samples are from the Rio Puerco Volcanic Field (RP) which overlaps the central RGR and southeastern Colorado Plateau; seventeen samples are from Kilbourne Hole (KH) in the southern RGR. Spinel Cr# (Cr/(Cr+Al) = 0.08-0.46) and olivine Mg# (Mg/(Mg+Fe) = 0.883-0.911) of samples fall within the olivine-spinel mantle array from [1], an indicator that these are residues of partial melting. Pyroxene H2O contents in KH correlate with bulk rock and pyroxene Al2O3 contents. The KH clinopyroxene rare earth element (REE) variations fit models of 0-13% fractional melting of a primitive upper mantle. Most KH peridotites have bulk-rock light REE depleted patterns, but five are enriched in light REEs consistent with metasomatism. Variation in H2O content seems unrelated to REE enrichment. Metasomatism is seen in RP pyroxenite xenoliths [2] and will be examined in the peridotites studied here. Olivine H2O contents are low (≤20 ppm), and decrease from core to rim within grains. This is likely due to H loss during xenolith transport by the host magma [3]. Diffusion models of H suggest that mantle H2O contents are still preserved in cores of KH olivine, but not those of RP olivine. The average H2O content of Colorado Plateau clinopyroxene (670 ppm) [4] is ~300 ppm higher than RGR clinopyroxene (350 ppm). This upholds the hypothesis that hydration-induced lithospheric melting occurred during flat-slab subduction of the Farallon plate [5]. Numerical models indicate hydration via slab fluids is possible beneath the plateau, ~600 km from the paleo-trench, but less likely ~850 km away beneath the rift [6]. [1]Arai, 1994 CG 113, 191-204.[2]Porreca et al., 2006 Geosp 2, 333-351.[3]Peslier and Luhr, 2006 EPSL 242, 302-319.[4]Li et al., 2008 JGR 113, 1978-2012.[5]Humphreys et al., 2003 Int Geol Rev 45, 575-595.[6]English et al., 2003 EPSL 214, 619-632.

Rare earth element distributions in the West Pacific: Trace element sources and conservative vs. non-conservative behavior

NASA Astrophysics Data System (ADS)

Behrens, Melanie K.; Pahnke, Katharina; Paffrath, Ronja; Schnetger, Bernhard; Brumsack, Hans-Jürgen

2018-03-01

Recent studies suggest that transport and water mass mixing may play a dominant role in controlling the distribution of dissolved rare earth element concentrations ([REE]) at least in parts of the North and South Atlantic and the Pacific Southern Ocean. Here we report vertically and spatially high-resolution profiles of dissolved REE concentrations ([REE]) along a NW-SE transect in the West Pacific and examine the processes affecting the [REE] distributions in this area. Surface water REE patterns reveal sources of trace element (TE) input near South Korea and in the tropical equatorial West Pacific. Positive europium anomalies and middle REE enrichments in surface and subsurface waters are indicative of TE input from volcanic islands and fingerprint in detail small-scale equatorial zonal eastward transport of TEs to the iron-limited tropical East Pacific. The low [REE] of North and South Pacific Tropical Waters and Antarctic Intermediate Water are a long-range (i.e., preformed) laterally advected signal, whereas increasing [REE] with depth within North Pacific Intermediate Water result from release from particles. Optimum multiparameter analysis of deep to bottom waters indicates a dominant control of lateral transport and mixing on [REE] at the depth of Lower Circumpolar Deep Water (≥3000 m water depth; ∼75-100% explained by water mass mixing), allowing the northward tracing of LCDW to ∼28°N in the Northwest Pacific. In contrast, scavenging in the hydrothermal plumes of the Lau Basin and Tonga-Fiji area at 1500-2000 m water depth leads to [REE] deficits (∼40-60% removal) and marked REE fractionation in the tropical West Pacific. Overall, our data provide evidence for active trace element input both near South Korea and Papua New Guinea, and for a strong lateral transport component in the distribution of dissolved REEs in large parts of the West Pacific.

Residual levels of rare earth elements in freshwater and marine fish and their health risk assessment from Shandong, China.

PubMed

Yang, Luping; Wang, Xining; Nie, Hongqian; Shao, Lijun; Wang, Guoling; Liu, Yongjun

2016-06-15

The total concentrations of rare earth elements (ΣREE) were quantified in 251 samples from 10 common species of freshwater and marine fish in seventeen cities of Shandong, China. ΣREE obtained from the freshwater fish ranged from 34.0 to 37.9ngg(-1) (wet weight) and marine fish from 12.7 to 37.6ngg(-1). The ratio of LREE to HREE was 13.7:1 and 10:1 for freshwater and marine fish, respectively. This suggests that freshwater fish exhibit greater REE concentrations than marine fish and the biological effects of LREE are higher than HREE. Results revealed a similar REE distribution pattern between those fish and coastal sediments, abiding the "abundance law". The health risk assessment demonstrated the EDIs of REEs in fish were significantly lower than the ADI, indicating that the consumption of these fish presents little risk to human health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geochemical Study on an Abandoned Copper Smelting Plant Using Rare Earth Elements

NASA Astrophysics Data System (ADS)

Sun, S. H.

2017-12-01

The Shuei Nan Dong Copper Smelting Plant smelting is located on the northern coast of New Taipei City, Taiwan. The plant built in 1906 for but has been shut down since 1987. However, the watershed is continuing to discharge acid mine water into the sea; and, the acid mine drainage releases high amounts of sulfate, heavy metals without any treatment. In this study, the water samples were sequentially collected along the main channel and its tributaries in the watershed. The results of hydrochemical analysis show that the untreated inflow water can be characterized with low pH value of <3 and enriched sulfate, copper and arsenic. However, the water is much less contaminated in the upstream area until a major tributary converge. The results of principal component analysis (PCA) demonstrate that the first principal component (PC) can explain >80% of the total variance and almost all chemical components have high loadings in the PC. Therefore, the hydrochemical properties in the watershed are mainly dominated by the mixing process between main channel and the major tributary but the geochemical reactions during flow down the channel is insignificant. Rare earth elements (REE) are an excellent tracer, which can indicate sources of chemical components and geochemical reactions in water. The analysis results demonstrate two distinct REE patterns. The water with low REE can be characterized by prominent Eu positive anomaly and Ce negative anomaly, which may result from the alteration of Na-plagioclase in sandstone and oxidation reaction when contact with air, respectively. On the contrary, the water with high REE shows only minor Ce negative anomaly and insignificant Eu positive anomaly. In addition, there is an enrichment of middle REE in high-REE water, which is quite different with the REE pattern of pyrite. According to the Grawunder's study (2014), it corresponds to the complexation to sulphite during pyrite oxidation. It is worth noting that REE show no considerable fractionation along the channel and confirms the results from PCA. It can be derived that the water may not reached equilibrium condition. A simple aerated retention pool could dramatically reduce the pollutants due to coprecipitation of iron oxide and aluminum oxide.

Trace element evaluation of a suite of rocks from Reunion Island, Indian Ocean

USGS Publications Warehouse

Zielinski, R.A.

1975-01-01

Reunion Island consists of an olivine-basalt shield capped by a series of flows and intrusives ranging from hawaiite through trachyte. Eleven rocks representing the total compositional sequence have been analyzed for U, Th and REE. Eight of the rocks (group 1) have positive-slope, parallel, chondrite-normalized REE fractionation patterns. Using a computer model, the major element compositions of group 1 whole rocks and observed phenocrysts were used to predict the crystallization histories of increasingly residual liquids, and allowed semi-quantitative verification of origin by fractional crystallization of the olivine-basalt parent magma. Results were combined with mineral-liquid distribution coefficient data to predict trace element abundances, and existing data on Cr, Ni, Sr and Ba were also successfully incorporated in the model. The remaining three rocks (group 2) have nonuniform positive-slope REE fractionation patterns not parallel to group 1 patterns. Rare earth fractionation in a syenite is explained by partial melting of a source rich in clinopyroxene and/or hornblende. The other two rocks of group 2 are explained as hybrids resulting from mixing of syenite and magmas of group 1. ?? 1975.

Dissolved rare earth elements in the central-western sector of the Ross Sea, Southern Ocean: Geochemical tracing of seawater masses.

PubMed

Turetta, Clara; Barbaro, Elena; Capodaglio, Gabriele; Barbante, Carlo

2017-09-01

The present essay contributes to the existing literature on rare earth elements (REEs) in the southern hemisphere by presenting the first data, to our knowledge, on the vertical profiles of dissolved REEs in 71 samples collected in the central-western sector of the Ross Sea (Southern Ocean-SO). The REEs were measured in the water samples collected during the 2002-2003 and 2005-2006 austral summers. 4 samples were collected and analysed in the framework of a test experiment, as part of the WISSARD Project (Whillans Ice Stream Subglacial Access Research Drilling). Our results show significant differences between the REE patterns of the main water masses present in the SO: we could observe specific signature in the High Salinity Shelf Water (HSSW), Ice Shelf Water (ISW) and Low Salinity Shelf Water (LSSW). A significant increase in Terbium (Tb) concentration was observed in the HSSW and ISW, the two principal water masses contributing to the formation of Antarctic Bottom Water (AABW) in the Ross Sea area, and in LSSW. Some of the HSSW samples show enrichment in Neodymium (Nd). Dissolved REE could therefore be used as tracers to understand the deep circulation of the SO (Pacific sector). We hypothesize that: (I) the characteristic dissolved REE pattern may derive from the composition of source area and from the hydrothermal activity of the central-western area of the Ross Sea; (II) the Tb anomaly observed in the AABW on the South Australian platform could be partially explained by the contribution of AABW generated in the Ross Sea region. Copyright © 2017 Elsevier Ltd. All rights reserved.

Diel behavior of rare earth elements in a mountain stream with acidic to neutral pH

USGS Publications Warehouse

Gammons, C.H.; Wood, S.A.; Nimick, D.A.

2005-01-01

Diel (24-h) changes in concentrations of rare earth elements (REE) were investigated in Fisher Creek, a mountain stream in Montana that receives acid mine drainage in its headwaters. Three simultaneous 24-h samplings were conducted at an upstream station (pH = 3.3), an intermediate station (pH = 5.5), and a downstream station (pH = 6.8). The REE were found to behave conservatively at the two upstream stations. At the downstream station, REE partitioned into suspended particles to a degree that varied with the time of day, and concentrations of dissolved REE were 2.9- to 9.4-fold (190% to 830%) higher in the early morning vs. the late afternoon. The decrease in dissolved REE concentrations during the day coincided with a corresponding increase in the concentration of REE in suspended particles, such that diel changes in the total REE concentrations were relatively minor (27% to 55% increase at night). Across the lanthanide series, the heavy REE partitioned into the suspended solid phase to a greater extent than the light REE. Filtered samples from the downstream station showed a decrease in shale-normalized REE concentration across the lanthanide series, with positive anomalies at La and Gd, and a negative Eu anomaly. As the temperature of the creek increased in the afternoon, the slope of the REE profile steepened and the magnitude of the anomalies increased. The above observations are explained by cyclic adsorption of REE onto suspended particles of hydrous ferric and aluminum oxides (HFO, HAO). Conditional partition coefficients for each REE between the suspended solids and the aqueous phase reached a maximum at 1700 hours and a minimum at 0700 hours. This pattern is attributed to diel variations in stream temperature, possibly reinforced by kinetic factors (i.e., slower rates of reaction at night than during the day). Estimates of the enthalpy of adsorption of each REE onto suspended particles based on the field results averaged +82 kJ/mol and are similar in magnitude to estimates in the literature for adsorption of divalent metal cations onto clays and hydrous metal oxides. The results of this study have important implications to the use of REE as hydrogeochemical tracers in streams. Copyright ?? 2005 Elsevier Ltd.

Transport and transformation of riverine neodymium isotope and rare earth element signatures in high latitude estuaries: A case study from the Laptev Sea

NASA Astrophysics Data System (ADS)

Laukert, Georgi; Frank, Martin; Bauch, Dorothea; Hathorne, Ed C.; Gutjahr, Marcus; Janout, Markus; Hölemann, Jens

2017-11-01

Marine neodymium (Nd) isotope and rare earth element (REE) compositions are valuable tracers for present and past ocean circulation and continental inputs. Yet their supply via high latitude estuaries is largely unknown. Here we present a comprehensive dissolved Nd isotope (expressed as εNd values) and REE data set together with seawater stable oxygen isotope (δ18O) compositions of samples from the Laptev Sea recovered in two Arctic summers and one winter. The Laptev Sea is a shallow Siberian Shelf sea characterized by extensive river-runoff, sea-ice production and ice transport into the Arctic Ocean. The large variability in εNd (-6 to -17), REE concentrations (16 to 600 pmol/kg for Nd) and REE patterns is controlled by freshwater supply from distinct riverine sources and open ocean Arctic Atlantic Water. Strikingly and contrary to expectations, except for cerium no evidence for significant release of REEs from particulate phases is found, which is attributed to low amounts of suspended particulate matter and high dissolved organic carbon concentrations present in the contributing rivers. Essentially all shelf waters are depleted in light (L)REEs, while the distribution of the heavy REEs shows a deficiency at the surface and a pronounced excess in the bottom layer. This distribution is consistent with REE removal through coagulation of riverine nanoparticles and colloids starting at salinities near 10 and resulting in a drop of all REE concentrations by ∼30%. With increasing salinity preferential LREE removal is observable reaching ∼75% for Nd at a salinity of 34. Although the delayed onset of dissolved REE removal contrasts with most previous observations from other estuarine environments, it agrees remarkably well with results from recent experiments simulating estuarine mixing of seawater with organic-rich river waters. In addition, melting and formation of sea ice leads to further REE depletion at the surface and strong REE enrichment near the shelf bottom as a function of ice melting and brine transfer, respectively. The ice-related processes significantly affect the distribution of dissolved REEs in high-latitude estuaries and likely also similarly contribute to the redistribution of other dissolved seawater constituents.

Trace Element Inputs to the Upper West Pacific from Nd Isotopes and Rare Earth Elements

NASA Astrophysics Data System (ADS)

Behrens, M. K.; Pahnke, K.; Schnetger, B.; Brumsack, H. J.

2015-12-01

Neodymium isotopes (143Nd/144Nd, expressed as ɛNd) and rare earth element (REE) concentrations in the ocean trace water mass transport and margin-seawater exchange processes. The distinct ɛNd and REE signatures of the lithogenic components of margin sediments of the West Pacific allow characterization of trace element inputs to the Pacific Ocean. We present dissolved ɛNdand REE concentrations from twelve vertical profiles of a transect from South Korea to Fiji. Near South Korea, surface waters are marked by unradiogenic ɛNd (as low as -7.3), high REE concentrations (e.g., Nd = 15.3 pmol/kg) and low salinity. Towards the open ocean, these parameters gradually change towards typical Pacific open ocean values (ɛNd = -3.3, [Nd] = 5.55 pmol/kg). Subsurface waters show REE depletions, followed by the typical REE increase with increasing water depth. These distributions indicate trace element input near South Korea and enhanced subsurface scavenging, as indicated by strong heavy REE to light REE fractionation. In the tropical West Pacific (10°N-15°S), high surface and subsurface water ɛNd values (+0.7) and positive Eu anomalies trace the influence of volcanic islands. Yet, absolute REE concentrations are extremely low at these depths (e.g., Nd = 2.77 pmol/kg). Using shale-normalized Nd/Er and Ho/Dy ratios, that show a much stronger surface to subsurface decrease in coastal waters compared to the open ocean, we suggest enhanced scavenging in this area. Eastward flowing intermediate waters (NPIW, AAIW) have ɛNd values up to +1.9 (NPIW) and +3.7 (AAIW) higher than those entering the tropical West Pacific from north and south, respectively. Modified ɛNd at intermediate depths and no change in REE patterns suggest that boundary exchange along volcanic island margins modifies the seawater ɛNd without changing the REE budget.

In situ U-Th-Pb ages of the Miaoya carbonatite complex in the South Qinling orogenic belt, central China

NASA Astrophysics Data System (ADS)

Ying, Yuancan; Chen, Wei; Lu, Jue; Jiang, Shao-Yong; Yang, Yueheng

2017-10-01

The Miaoya carbonatite complex in the South Qinling orogenic belt hosts one of the largest rare earth element (REE)-Nb deposits in China that is composed of carbonatite and syenite. The emplacement age of the complex and the geochronological relationship between the carbonatite and syenite have long been debated. In this study, in situ U-Th-Pb ages have been obtained for the constituent minerals zircon, monazite and columbite from carbonatite and syenite of the Miaoya complex, together with their chemical and isotopic compositions. In situ trace element compositions for zircon from carbonatite and syenite are highly variable. The zircon displays slightly heavy REE (HREE)-enriched chondrite-normalized patterns with no Eu anomaly and various light REE (LREE) contents. In situ Th-Pb dating for zircon from the Miaoya complex by laser ablation ICP-MS yields ages of 442.6 ± 4.0 Ma (n = 53) for syenite and 426.5 ± 8.0 Ma (n = 23) for carbonatite. Monazite from carbonatite and syenite shows similar chondrite-normalized REE patterns and yields a consistent Th-Pb age of 240 Ma. Based on petrographic and chemical composition, columbite from the carbonatite can be identified into two groups. The columbite dispersed within carbonatite is characterized by slightly LREE-enriched chondrite-normalized REE patterns, whereas columbite associated with apatite is characterized by LREE-depleted trends. Columbite has been further determined to have a weighted mean 206Pb/238U age of 232.8 ± 4.5 Ma (n = 9) using LA-ICP-MS. Detailed geochronological and chemical investigations suggest that there were two major episodes of magmatic/metasomatic activities in the formational history of the Miaoya carbonatite complex. The early alkaline magmatism emplaced in the Silurian was related to the opening of the Mianlue Ocean, whereas the late metasomatism or hydrothermal overprint occurred during the Triassic South Qinling orogeny. The latter serves as the major ore formation period for both REE (e.g., monazite) and Nb (e.g., columbite).

Rare earth element abundances in presolar SiC

NASA Astrophysics Data System (ADS)

Ireland, T. R.; Ávila, J. N.; Lugaro, M.; Cristallo, S.; Holden, P.; Lanc, P.; Nittler, L.; Alexander, C. M. O'D.; Gyngard, F.; Amari, S.

2018-01-01

Individual isotope abundances of Ba, lanthanides of the rare earth element (REE) group, and Hf have been determined in bulk samples of fine-grained silicon carbide (SiC) from the Murchison CM2 chondrite. The analytical protocol involved secondary ion mass spectrometry with combined high mass resolution and energy filtering to exclude REE oxide isobars and Si-C-O clusters from the peaks of interest. Relative sensitivity factors were determined through analysis of NIST SRM reference glasses (610 and 612) as well as a trace-element enriched SiC ceramic. When normalised to chondrite abundances, the presolar SiC REE pattern shows significant deficits at Eu and Yb, which are the most volatile of the REE. The pattern is very similar to that observed for Group III refractory inclusions. The SiC abundances were also normalised to s-process model predictions for the envelope compositions of low-mass (1.5-3 M⊙) AGB stars with close-to-solar metallicities (Z = 0.014 and 0.02). The overall trace element abundances (excluding Eu and Yb) appear consistent with the predicted s-process patterns. The depletions of Eu and Yb suggest that these elements remained in the gas phase during the condensation of SiC. The lack of depletion in some other moderately refractory elements (like Ba), and the presence of volatile elements (e.g. Xe) indicates that these elements were incorporated into SiC by other mechanisms, most likely ion implantation.

Anthropogenic rare earth elements and their spatial distributions in the Han River, South Korea.

PubMed

Song, Hyeongseok; Shin, Woo-Jin; Ryu, Jong-Sik; Shin, Hyung Seon; Chung, Heesun; Lee, Kwang-Sik

2017-04-01

Rare earth elements (REE) consist of lanthanides (from La to Lu), together with yttrium and scandium, in which anthropogenic REE, such as gadolinium (Gd), lanthanum (La), and samarium (Sm), has emerged as micro-contaminants in natural waters in highly developed countries. Here, we collected water samples in the Han River (HR) and its tributaries flowing through Seoul Capital Area, the world's second largest metropolitan area in order to examine how and to what extent anthropogenic REE anomalies may occur. Water samples show higher light REE concentrations than heavy REE concentrations, while wastewater treatment plant (WWTP) samples display much higher heavy REE concentrations due to high Gd concentration. The PAAS-normalized REE patterns indicate that WWTP samples display the pronounced positive Gd anomalies, in which anthropogenic Gd from magnetic resonance imaging (MRI) diagnostic system occurs as a form of Gd complexation with either Cl - or SO 4 2- . Due to the WWTP, both the HR and tributaries show also positive Gd anomalies and the anthropogenic Gd concentrations increase as a function of the distance from the Paldang dam. This result indicates a positive correlation between populaton, number of MRI instruments, and positive Gd anomaly. Similarly, positive La and Sm anomalies exist in the HR, indicating that the HR is also affected by their point sources. Based on the discharge rate and anthropogenic REE concentrations, their fluxes are estimated to be 952 ± 319 kg/yr, suggesting that this amount of fluxes could disturb REE distribution in the Yellow Sea, and pose harmful effects on aquatic ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tectonic origin of serpentinites on Syros, Greece: Geochemical signatures of abyssal origin preserved in a HP/LT subduction complex

NASA Astrophysics Data System (ADS)

Cooperdock, Emily H. G.; Raia, Natalie H.; Barnes, Jaime D.; Stockli, Daniel F.; Schwarzenbach, Esther M.

2018-01-01

This study combines whole rock trace and major element geochemistry, and stable isotope (δD and δ18O) analyses with petrographic observations to deduce the origin and tectonic setting of serpentinization of ultramafic blocks from the exhumed HP/LT Aegean subduction complex on Syros, Greece. Samples are completely serpentinized and are characterized by mineral assemblages that consist of variable amounts of serpentine, talc, chlorite, and magnetite. δD and δ18O values of bulk rock serpentinite powders and chips (δD = - 64 to - 33‰ and δ18O = + 5.2 to + 9.0‰) reflect hydration by seawater at temperatures < 250 °C in an oceanic setting pre-subduction, or by fluids derived from dehydrating altered oceanic crust during subduction. Fluid-mobile elements corroborate the possibility of initial serpentinization by seawater, followed by secondary fluid-rock interactions with a sedimentary source pre- or syn-subduction. Whole rock major element, trace element, and REE analyses record limited melt extraction, exhibit flat REE patterns, and do not show pronounced Eu anomalies. The geochemical signatures preserved in these serpentinites argue against a mantle wedge source, as has been previously speculated for ultramafic rocks on Syros. Rather, the data are consistent with derivation from abyssal peridotites in a hyper-extended margin setting or mid-ocean ridge and fracture zone environment. In either case, the data suggest an extensional and/or oceanic origin associated with the Cretaceous opening of the Pindos Ocean and not a subduction-related derivation from the mantle wedge.

Preferred-rupture propagation to the hangingwall of the shallow part of the out-of-sequence thrust: Ishido Fault in Boso Peninsula, central Japan

NASA Astrophysics Data System (ADS)

Yamamoto, Y.; Fukuyama, M.; Ujiie, K.; Hirose, T.; Hamada, Y.; Kitamura, M.; Kamiya, N.

2016-12-01

Although earthquake ruptures in shallow portion of plate boundary have recently been identified (e.g. Tohoku, Nankai, etc.), their mechanisms why the shallow portion of plate boundary composed mainly of clay minerals can accumulate strain and make seismic slip are under controversial. An ancient out-of-sequence thrust which divided the early and late Miocene accretionary complexes in the Boso Peninsula, central Japan records rupture propagation to the shallow portion of accretionary prism (< 2 km). The fault core is composed of black-colored thin (<1 mm) pseudotachylite and fluidized fault gouge. The former is characterized by homogeneous glassy matrix including fragments of quartz/feldspar, submicron-sized Fe-rich spherules, and vesicles. Based on the mineralogy of the host rock and EDS analyses of matrices, origin of the pseudotachylite was apparently frictional melting of smectite containing Fe. Fe-rich spherules formed by rapid cooling of pseudotachylite. On the other hand, overturned fault-related drag fold developed in the footwall, within about 30 m. Although some Riedel sheared normal faults developed in the overturned footwall, no other brittle deformations were identified. These occurrences imply coexistence of low- and high-speed slips along the same thrust fault. The whole-rock major and trace elemental analyses using XRF and ICP-MS show that mudstone in the hangingwall has similar chemical composition to those of pseudotachylite and fluidized fault gouge with REE enriched patterns, whereas the footwall has different chemical characteristics with relatively flat REE pattern and low LOI. Therefore, the protolith of pseudotachylite and fluidized fault gouge is mudstone in the hangingwall. These data imply that rupture propagation preferably occurred in the hangingwall along the fault zone. The footwall was also deformed apparently during slow-slip deformation leading to formation of the overturn, whereas only the hangingwall, just side of the fault zone, slipped under high-speed shear.

Trace element distribution in peridotite xenoliths from Tok, SE Siberian craton: A record of pervasive, multi-stage metasomatism in shallow refractory mantle

NASA Astrophysics Data System (ADS)

Ionov, Dmitri A.; Chazot, Gilles; Chauvel, Catherine; Merlet, Claude; Bodinier, Jean-Louis

2006-03-01

Spinel peridotite xenoliths in alkali basalts at Tok, SE Siberian craton range from fertile lherzolites to harzburgites and wehrlites; olivine-rich (70-84%) rocks are dominant. REE patterns in the lherzolites range from nearly flat for fertile rocks (14-17% cpx) to LREE-enriched; the enrichments are positively correlated with modal olivine, consistent with high-permeability of olivine-rich rocks during melt percolation. Clinopyroxene in olivine-rich Tok peridotites typically has convex-upward trace element patterns (La/Nd PM < 1 and Nd/Yb PM ≫ 1), which we consider as evidence for equilibration with evolved silicate liquids (with higher REE and lower Ti contents than in host basalts). Whole-rock patterns of the olivine-rich xenoliths range from convex-upward to LREE-enriched (La/Nd PM > 1); the LREE-enrichments are positively correlated with phosphorus abundances and are mainly hosted by accessory phosphates and P-rich cryptocrystalline materials. In addition to apatite, some Tok xenoliths contain whitlockite (an anhydrous, halogen-poor and Na-Mg-rich phosphate), which is common in meteorites and lunar rocks, but has not been reported from any terrestrial mantle samples. Some olivine-rich peridotites have generations of clinopyroxene with distinct abundances of Na, LREE, Sr and Zr. The mineralogical and trace element data indicate that the lithospheric mantle section represented by the xenoliths experienced a large-scale metasomatic event produced by upward migration of mafic silicate melts followed by percolation of low- T, alkali-rich melts and fluids. Chromatographic fractionation and fractional crystallisation of the melts close to the percolation front produced strong LREE-enrichments, which are most common in the uppermost mantle and are related to carbonate- and P 2O 5-rich derivatives of the initial melt. Reversal and gradual retreat of the percolation front during thermal relaxation to ambient geotherm ("retrograde" metasomatism) caused local migration and entrapment of small-volume residual fluids and precipitation of volatile-rich accessory minerals. A distinct metasomatic episode, which mainly produced "anhydrous" late-stage interstitial materials was concomitant with the alkali basaltic magmatism, which brought the xenoliths to the surface.

Determination and distribution of rare earth elements in beach rock samples using instrumental neutron activation analysis (INAA)

NASA Astrophysics Data System (ADS)

Ravisankar, R.; Manikandan, E.; Dheenathayalu, M.; Rao, Brahmaji; Seshadreesan, N. P.; Nair, K. G. M.

2006-10-01

Beach rocks are a peculiar type of formation when compared to other types of rocks. Rare earth element (REE) concentrations in beach rock samples collected from the South East Coast of Tamilnadu, India, have been measured using the instrumental neutron activation analysis (INAA) single comparator K0 method. The irradiations were carried out using a thermal neutron flux of ˜10 11 n cm -2 s -1 at 20 kW power using the Kalpakkam mini reactor (KAMINI), IGCAR, Kalpakkam, Tamilnadu. Accuracy and precision were evaluated by assaying irradiated standard reference material (SRM 1646a estuarine sediment). The results being found to be in good agreement with certified values. REE elements have been determined from 15 samples using high-resolution gamma spectrometry. The geochemical behavior of REE in beach rock, in particular REE (chondrite-normalized) pattern has been studied.

Rare earth elements in minerals of the ALHA77005 shergottite and implications for its parent magma and crystallization history

NASA Technical Reports Server (NTRS)

Lundberg, Laura L.; Crozaz, Ghislaine; Mcsween, Harry Y., Jr.

1990-01-01

Analyses of mineral REE and selected minor and trace elements were carried out on individual grains of pyroxenes, whitlockite, maskelynite, and olivine of the Antarctic shergottite ALHA77005, and the results are used to interpret its parent magma and crystallization history. The results of mineral compositions and textural observations suggest that ALHA77005 is a cumulate with about half cumulus material (olivine + chromite) and half postcumulus phases. Most of the REEs in ALHA77005 reside in whitlockite whose modal concentration is about 1 percent. Mineral REE data support previous suggestions that plagioclase and whitlockite crystallized late, and that low-Ca pyroxene initiated crystallization before high-Ca pyroxene. The REE patterns for the intercumulus liquid, calculated from distribution coefficients for ALHA77005 pyroxene, plagioclase, and whitlockite, are in very good agreement and are similar to that of Shergotty.

Crystallization process of zircon and fergusonite during hydrothermal alteration in Nechalacho REE deposit, Thor Lake, Canada

NASA Astrophysics Data System (ADS)

Hoshino, M.; Watanabe, Y.; Murakami, H.; Kon, Y.; Tsunematsu, M.

2012-04-01

The core samples of two drill holes, which penetrate sub-horizontal mineralized horizons at Nechalacho REE deposit in the Proterozoic Thor Lake syenite, Canada, were studied in order to clarify magmatic and hydrothermal processes that enriched HFSE (e.g. Zr, Nb, Y and REE). Zircon is the most common REE minerals in Nechalacho REE deposit. The zircon is divided into five types as follows: Type-1 zircon occurs as single grain in phlogopite and the chondrite-normalized REE pattern is characterized by a steeply-rising slope from the LREE to the HREE with a positive Ce-anomaly and negative Eu-anomaly. This chemical characteristic is similar to that of igneous zircon. Type-2 zircon consists of HREE-rich magmatic porous core and LREE-Nb-F-rich hydrothermal rim. This type zircon is mostly included in phlogopite and fluorite, and occasionally in microcline. Type-3 zircon is characterized by euhedral to anhedral crystal, occurring in a complex intergrowth with REE fluorocarbonates. Type-3 zircons have high contents of REE, Nb and fluorine. Type-4 zircon consists of porous-core and -rim zones, but their chemical compositions are similar to each other. This type zircon is a subhedral crystal rimmed by fergusonite. Type-5 zircon is characterized by smaller, porous and subhedral to anhedral crystals. The interstices between small zircons are filled by fergusonite. Type-4 and -5 zircons show low REE and Nb contents. Occurrences of these five types of zircon are different according to the depth and degree of the alteration by hydrothermal solutions rich in F- and CO3 of the two drill holes, which permit a model for evolution of the zircon crystallization in Nechalacho REE deposit as follows: (1) type-1 (single magmatic zircon) is formed in miaskitic syenite. (2) LREE-Nb-F-rich hydrothermal zircon formed around HREE-rich magmatic zircon (type-2 zircon); (3) type-3 zircon crystallized thorough F and CO3-rich hydrothermal alteration of type-2 zircon which formed the complex intergrowth with REE fluorocarbonates; (4) the CO3-rich hydrothermal fluid corroded type-3, forming Nb-REE-poor zircons (type-3). Niobium and REE was no longer stable in the zircon structure and crystallized as fergusonite around the REE-Nb-leached zircon (type-4); (5) type-5 zircons are formed from more CO3-rich hydrothermal alteration of type-3 zircon. Therefore, type-4 and -5 zircons are often included in ankerite. Type 3-5 zircons at Nechalacho REE deposit were formed by leaching and/or dissolution of type-2 zircon in the presence of F- and/or CO3-rich hydrothermal fluid. The above mineral association indicates that three hydrothermal stages were present and related to HFSE enrichment in the Nechalacho REE deposit: (1) F-rich hydrothermal stage caused the crystallization of REE-Nb-rich zircon (type-2 rim and type-3), with abundant formation of phlogophite and fluorite, (2) F-CO3-rich hydrothermal stage led to the replacement of a part of REE-Nb-F-rich zircon by REE fluorocarbonate and (3) hydrothermal stage rich in CO3 resulted in crystallization of REE-Nb-F-poor zircon and fergusonite, with ankerite. Increases of HFSE contents, REE-Nb-F-poor zircon (type-4 and -5) and fergusonite contents during progress of hydrothermal alteration show that REE and Nb in hydrothermal fluid in the Nechalacho REE deposit were finally concentrated into fergusonite by way of zircon.

Rare earth elements in weathering profiles and sediments of Minnesota: Implications for provenance studies

USGS Publications Warehouse

Morey, G.B.; Setterholm, D.R.

1997-01-01

The relative abundance of rare earth elements in sediments has been suggested as a tool for determining their source rocks. This correlation requires that weathering, erosion, and sedimentation do not alter the REE abundances, or do so in a predictable manner. We find that the rare earth elements are mobilized and fractionated by weathering, and that sediments derived from the weathered materials can display modifications of the original pattern of rare earth elements of some due to grain-size sorting of the weathered material. However, the REE distribution pattern of the provenance terrane can be recognized in the sediments.

Nature of parent rocks, mineralization styles and ore genesis of regolith-hosted REE deposits in South China: An integrated genetic model

NASA Astrophysics Data System (ADS)

Li, Yan Hei Martin; Zhao, Wen Winston; Zhou, Mei-Fu

2017-10-01

Regolith-hosted rare earth element (REE) deposits, also called ion-adsorption or weathered crust elution-deposited REE deposits are distributed over Jiangxi, Guangdong, Fujian, Hunan, Guangxi and Yunnan provinces in South China. In general, these deposits can be categorized into the HREE-dominated type, for example the famous Zudong deposit in southern Jiangxi province and the LREE-dominated type, such as the Heling and Dingnan deposits in southern Jiangxi province. Most of these deposits form from weathering of biotite and muscovite granites, syenites, monzogranites, granodiorites, granite porphyries, and rhyolitic tuffs. The parent rocks are generally peraluminous, siliceous, alkaline and contain a variety of REE-bearing minerals. Mostly, REE patterns of regolith are inherited from the parent rocks, and therefore, characteristics of the parent rocks impose a significant control on the ore formation. Data compilation shows that autometasomatism during the latest stage of granite crystallization is likely essential in forming the HREE-enriched granites, whereas LREE-enriched granites could form through magmatic differentiation. These deposits are normally two- to three-fold, but could be up to ten-fold enrichment in REE compared to the parent granites, where the maximum enrichment usually occurs from the lower B to the upper C horizon. Ce shows different behavior with the other REEs. Strongly positive Ce anomalies commonly occur at the upper part of weathering profiles, likely due to oxidation of Ce3+ to Ce4+ and removal of Ce from soil solutions through precipitation of cerianite. Vertical pH and redox gradients in weathering crusts facilitate dissolution of REE-bearing minerals at shallow level and fixation of REE at depth through either adsorption on clay minerals or precipitation of secondary minerals. At the same time, mass removal of major elements plays an important role in concentrating REE in regolith. Combination of mass removal and eluviation-illuviation dynamics is the main mechanism for REE accumulation in weathering crusts. Favorable exogenetic factors facilitate the accumulation of REE in regolith and preservation of the ore bodies. These include quasi-equilibrium between denudation and exhumation at regional scales, local geomorphology dominated by low-lying gentle slopes, adequate rainfall, and favorable groundwater conditions. Continuous operation of such a dynamic weathering system is essential in the formation of regolith-hosted REE deposits.

Does sediment geochemistry (based on selective extractions of Al and Fe and REE) provide a record of soil evolution?

NASA Astrophysics Data System (ADS)

Mourier, B.; Poulenard, J.; Blarquez, O.; Williamson, D.; Arnaud, F.; Carcaillet, C.

2009-04-01

Soil is a natural body occurring at the interface between the lithosphere, atmosphere and biosphere. As a result, the physical and chemical properties of soils evolve with time, and the reconstruction of their history represents a key to understand past environmental changes. Palaeolimnological techniques such as sediment geochemistry can be used to investigate changes in catchment history by providing information about soil development. However, due to the lack of conservative pedosignatures (soil proxies), only few paleoecological studies have attempted to reconstruct the history of soil genesis using geochemical analyses of lacustrine sediments. Here we present a multidisciplinary study which aims to use pedosignatures, defined by a previous soil study, in order to characterize the history of soil genesis, podzolization and chemical weathering processes in two sediment sequences. Moreover, we aim to compare the timing of soil evolution with other paleoenvironmental markers (macroremains, charcoals…) in order to infer the role of climate, vegetation and possible human activities as forcing factors. In a first step, the geochemical investigation of eight subalpine soil profiles from the inner Alps allowed to define relevant proxies of two major soil processes. Parent material normalized REE patterns provide a precise tracer of chemical weathering whereas the proportions of secondary Al- and Fe-bearing phases provide a tracer of the podzolisation process. Then, the same tracers were assessed on two lacustrine and peat sediment sequences (Loup and Thyl lakes) from the subalpine domain. The proxy records, spanning ca. 4.500 yr at the Thyl lake and ca. 13.500 yr at the Loup lake, indicate that both progressive and regressive pedogenesis occurred after the deglaciation. The Thyl record is highly contrasted: the progressive setting of the mixed cembra pine ecosystem is associated to the podzolisation process (secondary Al- and Fe-bearing phases are maximal) and the increase of chemical weathering (enrichments of specific REE's fractions) that lasted totally ca. 1500 to 2000 years. Then, these progressive pathways are followed by abrupt and rapid secondary processes that could result from drastic transformation of the plant cover. The flat normalized REE patterns associated with low secondary Al and Fe values suggest a decrease of chemical weathering and podzolization. Moreover, the higher variability in cembra pine and the enrichment in sedge and other herbs remains in the lake suggest the setting of semi-open vegetation associated to the evidence of regressive soil processes. On the other hand, Loup environment and soil history are characterized by a progressive and stable evolution leading to present day old growing forests and Podzol soil type. Whereas the major sedimentological changes are sensitive to climate, the soil proxy records may be more triggered by the natural dynamic of the plant cover. At this site, human disturbances seem to have lower importance than at the Thyl site.

Rare earth elements and neodymium isotopes in sedimentary organic matter

NASA Astrophysics Data System (ADS)

Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

2014-09-01

We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter (inferred from the analysis of local surface seawater). A notable exception is the case of organic matter (OM) fractions leached from cold seep sediment samples, which sometimes exhibit εNd values markedly different from both terrigenous and surface seawater signatures. This suggests that a significant fraction of organic compounds in these sediments may be derived from chemosynthetic processes, recycling pore water REE characterized by a distinct isotopic composition. Overall, our results confirm that organic matter probably plays an important role in the oceanic REE budget, through direct scavenging and remineralization within the water column. Both the high REE abundances and the shape of shale-normalized patterns for leached SOM also suggest that OM degradation in sub-surface marine sediments during early diagenesis could control, to a large extent, the distribution of REE in pore waters. Benthic fluxes of organic-bound REE could hence substantially contribute to the exchange processes between particulates and seawater that take place at ocean margins. Neodymium isotopes could provide useful information for tracing the origin (terrestrial versus marine) and geographical provenance of organic matter, with potential applications in paleoceanography. In particular, future studies should further investigate the potential of Nd isotopes in organic compounds preserved in sedimentary records for reconstructing past variations of surface ocean circulation.

Trace Element Abundances in Refractory Inclusions from Antarctic Micrometeorites

NASA Astrophysics Data System (ADS)

Greshake, A.; Hoppe, P.; Bischoff, A.

1995-09-01

Refractory inclusions are charcteristic components in carbonaceous chondrites. Therefore, refractory inclusions found in micrometeorites can give important hints about the relationship between micrometeorites and carbonaceous chondrites. So far, only a few inclusions were found in micrometeorites [1-4]. In this study we report the first trace element analysis of perovskite and fassaite found in micrometeorites. We studied two Antarctic micrometeorites by ASEM, EMP, and SIMS. The first particle is 120 micrometers in size mainly consisting of a fine-grained matrix of dehydrated former phyllosilikates that enclose a 5 micrometers sized perovskite [5]. The perovskite is surrounded by a 1 micrometers thick rim of ilmenite and contains up to 1.3 wt% FeO as determined by EMP. The trace element abundances were determined by SIMS following the procedure described by [6]. The REE pattern of the perovskite is shown in Fig. 1. The pattern is closely related to the Group II pattern with its typical depletion of the more refractory REEs [7]. It is also very similar to the REE abundances of perovskite from Murchison (CM) [8] and CH-chondrites [9]. This may indicate a relationship between this micrometeorite and components in carbonaceous chondrites. The second micrometeorite is 100 micrometers in size consisting of a fine-grained (20 micrometers across) and a coarse-grained (80 micrometers across) area. Both areas contain fassaite with different chemical compositions. The particle was previously analyzed by Lindstrom and Kloeck [1] without knowing the mineralogy. We carried out SIMS analysis of each area of the micrometeorite separately. The TEE patterns of these two areas are similar and show in general a Group III pattern (20-30x CI) in which the more refractory REEs are not fractionated. The negative Eu anomaly is much more apparent in the coarse-grained area and no Yb anomaly is apparent in one of the areas. This is the first CAI of a micrometeorite showing a Group III REE pattern. References: [1] Lindstrom D. J. and Kloeck W. (1992) Meteoritics, 27, 250. [2] Kurat G. et al. (1994) Meteoritics, 29, 487-488. [3] Kurat G. et al. (1995) LPS XXV, 763-764. [4] Hoppe P. et al. (1995) LPS XXVI, 623-624. [5] Beckerling W. et al. (1992) Meteoritics, 27, 200-201. [6] Zinner E. and Crozaz G. (1986) Int. J. Mass. Spectr. Ion Processes, 69, 17-38. [7] Martin P. and Mason B. (1974) Nature, 249, 333-334. [8] Ireland T. et al. (1988) GCA, 52, 2841-2854. [9] Weber et al. (1995) GCA, 59, 803-823.

Archean greenstone belt magmatism and the continental growth-mantle evolution connection: constraints from Th-U-Nb-LREE systematics of the 2.7 Ga Wawa subprovince, Superior Province, Canada

NASA Astrophysics Data System (ADS)

Polat, Ali; Kerrich, Robert

2000-01-01

An extensive database, including Th-;U-Nb-REE systematics, for diverse magmatic and sedimentary lithologies of 2.7 Ga Wawa greenstone belts provide new constraints on the mechanism of crustal growth in the southern Superior Province, and controls on its composition. The greenstone belts are characterized by collages of oceanic plateaus, oceanic island arcs, and trench turbidites; these lithotectonic fragments were tectonically assembled in a large subduction-accretion complex. Following juxtaposition, these diverse lithologies were collectively intruded by syn-kinematic TTG (tonalite-trondhjemite-granodiorite) plutons and ultramafic to felsic dykes and sills, with subduction zone geochemical signatures. Intra-oceanic basalts are characterized by near-flat REE patterns, and Nb/U and Nb/Th ratios generally greater than primitive mantle values, consistent with positive ɛNd values. They are associated with komatiites, the association being interpreted as an ocean plateau sequence erupted from a mantle plume. Bimodal arc volcanic sequences, trench turbidites, and contemporaneous TTG suites are characterized by fractionated REE, with Nb/U and Nb/Th ratios less than primitive mantle values. Mixing hyperbolae between oceanic plateau and magmatic arc sequences pass through the estimated composition of bulk continental crust, suggesting that crustal growth in the late Archean was by tectonic, sedimentary, and chemical mixing of oceanic plateau and arc sequences at convergent plate boundaries. Mixing calculations suggest that oceanic plateau and subduction zone components in the Wawa continental crust are represented by 6-12% and 88-94%, respectively. High Nb/U and Nb/Th ratios of plateau tholeiitic basalts are interpreted as a complementary reservoir to arc magmatism (low Nb/U and Nb/Th), hundreds of millions of years prior to recycling of oceanic lithosphere through a subduction zone (high Nb/U, Nb/Th), and its incorporation into a mantle plume from which 2.7 Ga plateau tholeiites erupted. The variably high Nb/U ratios of the plateau basalts are consistent with early extraction of large quantities of the protoliths (magmatic precursor) of continental crust from the southern Superior Province asthenospheric mantle.

Zircon U-Pb chronology, geochemistry and Sr-Nd-Pb isotopic compositions of the Volcanic Rocks in the Elashan area, NW China: petrogenesis and tectonic implications

NASA Astrophysics Data System (ADS)

Zhou, H.; Wei, J.; Shi, W.; Li, P.; Chen, M.; Zhao, X.

2017-12-01

Elashan area is located in the intersection of the East Kunlun Orogenic Belt (EKOB) and the West Qinling Orogenic (WQOB). We present petrology, zircon U-Pb ages, whole-rock geochemistry and Sr-Nd-Pb isotopic compositions from the andesite and felsic volcanic rocks (rhyolite and rhyolitic tuffs) in Elashan group volcanic rock. The LA-ICP-MS zircon U-Pb age data indicate that the volcanic rocks are emplaced at 250 247 Ma. The volcanic rocks have high -K and aluminum - peraluminous characteristics, A/CNK = 1.07 1.82, δ ranges from 1.56 2.95, the main body is calc-alkaline rock. They are enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) and depleted in some high field strength elements (HFSEs, e.g., Nb, Ta, P and Ti), while having a flat heavy REE (HREEs) pattern. The ∑REE values of 178.68 to 298.11 ppm, average 230.50 ppm. The LREE/HREE values of 4.39 to 11.78 ppm, average 6.77 ppm. REE fractionation is obvious, REE distribution curve was right smooth, and have slightly negative Eu anomalies (Eu/Eu*=0.44-0.80, average 0.60), which as similar to the island arc volcanic rocks. The volcanic rocks have initial 87Sr/86Sr ratios of 0.71028-0.71232, ɛNd(t) values of -6.7 to -7.6, with T2DM-Nd ranging from 1561 to 1640 Ma. Pb isotopic composition (206 Pb / 204 Pb)t = 18.055 18.330, (207 Pb / 204 Pb)t = 15.586 15.618, (208 Pb / 204 Pb)t = 37.677 38.332. Geochemical and Sr-Nd-Pb isotopes indicates that Elashan group volcanic magma derived mainly from the lower crust. Elashan group volcanic rocks is the productive East Kunlun block and West Qinling block collision, which makes the thicken crust caused partial melting in the study area. The source rocks is probably from metamorphic sandstone of Bayankala. But with Y-Nb and Rb-(Y+Nb), R1-R2 and Rb/10-Hf-Ta*3 diagrams showing that intermediate-acid rocks mainly formed in volcanic arc-collision environment, probably the collision event is short , therefore rocks retain the original island arc properties. The formation age of intermediate -acidic volcanic rock can represent the time in which the end of transgressive and the beginning of intercontinental evolution in the northeastern Tibetan Plateau.

Temporal changes in Ce-anomalies in biogenic apatite from the Upper Cretaceous-Lower Eocene phosphate beds of Morocco. Is there a link to global paleoceanography?

NASA Astrophysics Data System (ADS)

Kocsis, L.; Gheerbrant, E.; Mouflih, M.; Cappetta, H.; Ulianov, A.

2012-12-01

Shallow marine phosphorites are widespread along the western coast of Morocco. These sediments were deposited in three, first order transgressive-regressive cycles during the late Cretaceous-early Eocene. The layers are exceptionally rich in marine vertebrate fossils and three periods - Maastrichtian, Danian-Thanetian and Ypresian - can be distinguished by the especially abundant selachian fauna. A comprehensive geochemical study is carried out on these biogenic apatite fossils, and here we present trace element data analyzed on enameloid and dentin of shark teeth, coprolites, and bones coming from the Ouled Abdoun and Ganntour Basins. A clear separation is apparent between enameloid and the other archives in terms of the former has lower Cu, Ba, rare earth elements (REE) and U, and higher Zn and Sr concentrations. The REE and U in phosphatic fossils originate almost entirely from early diagenetic pore fluid and thus they can be used as a fingerprint of burial conditions. The above observed differences in the trace element concentrations relate to the originally different structure of these fossils, which means the better crystallized and denser enameloid interacted less with the burial fluid than the other remains. All the fossils revealed very similar shale normalized REE patterns, with negative Ce-anomaly and heavy REE enrichment, which mimics the REE distribution of typical modern seawater. This would indicate that the early diagenetic pore fluid was dominated by seawater, when these fossils gained their REE composition. However, the patterns show small differences with lower La/Sm, and higher La/Yb and Sm/Yb ratios in the coprolites, dentine and bones, which would appear as slight flattening of the patterns on the heavy REE end. This signifies again that these latter archives are more susceptible to interaction with the pore fluid. In contrast, the Ce-anomaly does not vary among the different remains and the values are very similar in a given layer. However, more interestingly a gradual shift towards lower Ce/Ce* values from older to younger beds is evident. Three major causes could be responsible for this temporal Ce-anomaly shift. First is enhanced REE uptake with time and gradually less oxygenated early diagenetic environment in the deeper and older beds. This would predict higher total REE content in the older fossils, which is not observable in our record. Second is varying water depth in the basins that may relate to alternation in redox conditions in the burial environment. Clearly, sea-level fluctuation had an impact on the sedimentation in these shallow marine basins. However, Ce-anomaly appears to change before major sedimentary gaps. Third and our preferred interpretation is the negative Ce-anomaly shift indicates the presence of more oxygenated seawater in the basins. This region was controlled by upwelling currents from the Atlantic Ocean, hence the observed changes are presumed to be in this source. This would point to development of more oxygenated deepwater in the North Atlantic by the end of the Paleocene, which may link to the extended opening of the North Atlantic and its connection to the South Atlantic.

Rare earth element evidence for the petrogenesis of the banded series of the Stillwater Complex, Montana, and its anorthosites

USGS Publications Warehouse

Loferski, P.J.; Arculus, R.J.; Czamanske, G.K.

1994-01-01

A rare earth element (REE) study was made by isotope-dilution mass spectrometry of plagioclase separates from a variety of cumulates stratigraphically spanning the Banded series of the Stillwater Complex, Montana. Evaluation of parent liquid REE patterns, calculated on the basis of published plagioclase-liquid partition coefficients, shows that the range of REE ratios is too large to be attributable to fractionation of a single magma type. At least two different parental melts were present throughout the Banded series. This finding supports hypotheses of previous workers that the Stillwater Complex formed from two different parent magma types, designated the anorthosite- or A-type liquid and the ultramafic- or U-type liquid. -from Authors

The surface sediment types and their rare earth element characteristics from the continental shelf of the northern south China sea

NASA Astrophysics Data System (ADS)

Wang, Shuhong; Zhang, Nan; Chen, Han; Li, Liang; Yan, Wen

2014-10-01

The grain size as well as some major and trace elements, including rare earth element (REE), for 273 surface sediment samples collected from the continental shelf of the northern South China Sea were analyzed in this study. The sediment types are mainly sandy silt and silt, making up 60% of the whole samples, and secondly are mud, sandy mud, muddy sand and silty sand, making up 28% of the whole samples, based on grain-size in which the Folk's classification was used. The total REE content (ΣREE) show a wide variation from 21 ppm to 244 ppm with an average value of 155 ppm, which similar to the average ΣREE of the China loess, but much different from that in deep-sea clay, showing a significant terrigenous succession. The REE contents in different sediment types vary greatly, mainly enriching in silt, sandy silt, mud and sandy mud. The REE distribution contours parallel to the coastal, presenting like strips and their contents gradually reduce with increasing distance from the coast. The high content of the western Pearl River Mouth, Shang/Xiachuan Islands and Hailing Bay might be regarded to the coastal current developed from the east to the west along to the Pearl River Mouth in the northern South China Sea. But the chondrite-normalized REE patterns in various sediment types have no difference, basically same as those of coastal rivers and upper crust. They all show relative enrichments in light rare earth element (LREE), noticeable negative Eu anomaly and no Ce anomaly, indicating that those sediments are terrigenous sediments and from the same source region. Further analysis suggest that the sedimentary environment in the study area is relatively stable and granite widely distributed in the South China mainland is the main source of REE, which are transported mainly by the Pearl River. The late diagenesis has little effect on the REE.

Anthropogenic gadolinium anomalies and rare earth elements in the water of Atibaia River and Anhumas Creek, Southeast Brazil.

PubMed

de Campos, Francisco Ferreira; Enzweiler, Jacinta

2016-05-01

The concentrations of rare earth elements (REE), measured in water samples from Atibaia River and its tributary Anhumas Creek, Brazil, present excess of dissolved gadolinium. Such anthropogenic anomalies of Gd in water, already described in other parts of the world, result from the use of stable and soluble Gd chelates as contrast agents in magnetic resonance imaging. Atibaia River constitutes the main water supply of Campinas Metropolitan area, and its basin receives wastewater effluents. The REE concentrations in water samples were determined in 0.22-μm pore size filtered samples, without and after preconcentration by solid-phase extraction with bis-(2-ethyl-hexyl)-phosphate. This preconcentration method was unable to retain the anthropogenic Gd quantitatively. The probable reason is that the Gd chelates dissociate slowly in acidic media to produce the free ion that is retained by the phosphate ester. Strong correlations between Gd and constituents or parameters associated with effluents confirmed the source of most Gd in water samples as anthropogenic. The shale-normalized REE patterns of Atibaia River and Anhumas Creek water samples showed light and heavy REE enrichment trends, respectively. Also, positive Ce anomalies in many Atibaia River samples, as well as the strong correlations of the REE (except Gd) with terrigenous elements, imply that inorganic colloidal particles contributed to the REE measured values.

Anomalous abundance and redistribution patterns of rare earth elements in soils of a mining area in Inner Mongolia, China.

PubMed

Wang, Lingqing; Liang, Tao

2016-06-01

The Bayan Obo Mine, the largest rare earth element (REE) deposit ever found in the world, has been mined for nearly 60 years for iron and rare earth elements. To assess the influences of mining activities on geochemical behavior of REEs in soils, 27 surface soil samples and three soil profile samples were collected from different directions in the vicinity of the mine area. The total concentrations of REEs in surface soils varied from 149.75 to 18,891.81 mg kg(-1) with an average value of 1906.12 mg kg(-1), which was apparently higher than the average values in China (181 mg kg(-1)). The order of the average concentrations of individual REEs in surface soils was similar to that in Bayan Obo ores, which confirmed that the concentration and distribution of REEs in the soils was influenced by the mining activities. The concentrations of single REE in the soil profiles showed a similar trend with depth with an increase at 0-25 cm section, then decreased and remained relatively stable in the deep part. The normalized curves inclined to the right side, showing the conspicuous fractionation between the light and heavy REEs, which supported by the North American Shale Composite (NASC) and Post-Archean Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La N /Yb N , La N /Sm N , Gd N /Yb N ). Slight positive Ce anomaly and negative Eu anomaly were also observed.

African Dust Transport Captured by Rare Earth Elemental Concentrations in Coral Microatolls

NASA Astrophysics Data System (ADS)

Ouellette, G., Jr.; DeLong, K.; Herrmann, A.; Huang, C. Y.; Shen, C. C.

2017-12-01

Winds are integral components of the climate system; unfortunately, windsare also among the climate variables that are most difficult to study prior to the instrumentalrecord. Paleoclimatologists use sedimentary dust records (e.g., lake and ocean cores) tounderstand past wind circulation conditions; however, these types of records typically are notamenable to sub-annual interpretation due to their limited temporal resolution. Here wedeveloped a coral-based dust-wind proxy to overcome these temporal limitations by usingtrace (nmol/mol) rare earth elemental concentrations recorded in the skeletons of coralmicroatolls. The rare earth elements (REE; the lanthanides as well as scandium and yttrium)behave similarly in geologic and geochemical systems, and have served as useful proxies ofgeological processes in both deep and shallow time. Corals incorporate REE as they deposittheir exoskeletons that extend incrementally with time forming annual density band couplets.Coral microatolls grow at or near the sea surface, where coral REE concentrations are mostsensitive to dust deposition. Our study site off the west coast of Haiti is down stream of light-REE depleted bedrock whereas REE in African dust, transported by the easterly trade winds,reflect average crustal abundances. This unique "upstream" source signature allows forterrestrial contamination of the dust-wind signal to be ruled out. Light REE concentrations (esp.Nd and Pr) demonstrate an order of magnitude increase within coral aragonite coincident withmajor African dust plume events throughout the past decade, with Nd/Ca and Pr/Ca increasingfrom an average of 27 nmol/mol to an average 144 nmol/mol and an average of 5 nmol/mol toan average of 37 nmol/mol, respectively, during major African dust plume events. Monthly-resolved REE analysis shows these REE peaks coincide with the summer dust season rather thanHaiti's two wet seasons in spring and autumn. Regression of our coral REE dust proxy tosatellite records of African dust aerosol optical depth (AOD) provides a significant transferfunction [(REE)=3.00(AOD)-3.11, R 2 = 0.72, p ≤ 0.0005, df= 24]. Our results suggest coral REErecords have the potential to robustly reconstruct past African dust plume transport, thusproviding insight into the regional easterly trade wind patterns driving them.

Aqueous Rare Earth Element Patterns and Concentration in Thermal Brines Associated With Oil and Gas Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nye, Charles; Quillinan, Scott Austin; Neupane, Ghanashyam

This study is part of a joint effort by the University of Wyoming (UW) School of Energy Resources (SER), the UW Engineering Department, Idaho National Laboratories (INL), and the United States Geological Survey (USGS) to describe rare earth element concentrations in oil and gas produced waters and in coal-fired power station ash ponds. In this work we present rare earth element (REE) and trace metal behavior in produced water from four Wyoming oil and gas fields and surface ash pond water from two coal-fired power stations. The concentration of REEs in oil and gas produced waters is largely unknown. Formore » example, of the 150,000 entries in the USGS National Produced Waters Geochemical Database less than 5 include data for REEs. Part of the reason for this scarcity is the analytical challenge of measuring REEs in high salinity, hydrocarbon-bearing waters. The industry standard for water analysis struggles to detect REEs in natural waters under ideal conditions. The detection of REEs in oil and gas field samples becomes all but impossible with the background noise and interferences caused by high concentrations of non-REE ions and residual hydrocarbons. The INL team members have overcome many of these challenges (e.g. McLing, 2014), and continue to develop their methods. Using the methods of the INL team members we measured REEs in high salinity oil and gas produced waters. Our results show that REEs exist as a dissolved species in all waters measured for this project, typically within the parts per trillion range. The samples may be grouped into two broad categories analytically, and these categories match their genesis: Wyoming oil and gas brines contain elevated levels of Europium, and Wyoming industrial pond waters show elevation in heavy REEs (HREEs). While broadly true, important variations exist within both groups. In the same field Europium can vary by more than an order of magnitude, and likewise HREEs in industrial ponds at the same site can vary by more than an order of magnitude. Future work will investigate the reasons for these variations.« less

Petrography, geochemistry and U-Pb zircon age of the Matongo carbonatite Massif (Burundi): Implication for the Neoproterozoic geodynamic evolution of Central Africa

NASA Astrophysics Data System (ADS)

Midende, Gilbert; Boulvais, Philippe; Tack, Luc; Melcher, Frank; Gerdes, Axel; Dewaele, Stijn; Demaiffe, Daniel; Decrée, Sophie

2014-12-01

The Matongo carbonatite intrusion belongs to the Neoproterozoic Upper Ruvubu alkaline plutonic complex (URAPC), that is located in Burundi along the western branch of the East African Rift. Beside the Matongo carbonatite, the URAPC alkaline complex comprises feldspathoidal syenites, diorites, quartz-bearing syenites and granites. Three main facies have been recognized in the Matongo carbonatite: (1) Sövites represent the dominant facies. Two varieties have been recognized. A scarce coarse-grained sövite (sövite I), which is altered and poorly enriched in REE (4 < ΣREE < 8 ppm), is encountered in highly fractured zones. A fine-grained sövite (sövite II), which is made of saccharoidal calcite, commonly associated with apatite, aegirine and amphibole, is abundant in the intrusion. Sövite II is enriched in LREE (442 < ΣREE < 1550 ppm, 49 < LaN/YbN < 175). (2) Ferrocarbonatites, that form decimeter-wide veins crosscutting the sövites, are characterized by a LREE enriched patterns (225 < ΣREE < 1048 ppm, 17 < LaN/YbN < 64). (3) K-feldspar and biotite-rich fenite facies (silicocarbonatites) have been recognized at the contact between the carbonatites and the country rock. They are likewise LREE-enriched (134 < ΣREE < 681 ppm, 25 < LaN/YbN < 46). Additionaly, "late" hydrothermal MREE-rich carbonatite veinlets can be found in sövite I. They are characterized by moderate enrichment in REE (ΣREE = 397 ppm), with a MREE-humped pattern (LaN/YbN = 3.7). The different facies represent the typical magmatic evolution of a carbonatite, while the silicocarbonatites are interpreted as resulting from the fenitisation of the country host-rocks. In addition, the most REE-depleted and fractionated facies, i.e. the coarse-grained sövite facies and the "late" calcite veinlets testify for hydrothermal processes that occurred after carbonatite emplacement and result from REE mobilization and redistribution. Large idiomorphic zircon crystals (megacrysts), found in the vicinity of the carbonatite can directly be related to the carbonatite evolution. They have been dated at 705.5 ± 4.5 Ma (U-Pb concordant age, LA-ICP-MS). Similar zircon megacrysts of the Lueshe carbonatite (DRCongo) have been dated and give a concordant age at 798.5 ± 4.9 Ma (U-Pb, LA-ICP-MS). Considering that an extensional tectonic regime occured at that time in Central Africa - what remains debated - both ages could relate to different stages of Rodinia breakup, with uprise of mantle-derived magmas along Palaeoproterozoic lithospheric zones of weakness.

An ion microprobe study of the intra-crystalline behavior of REE and selected trace elements in pyroxene from mare basalts with different cooling and crystallization histories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shearer, C.K.; Papike, J.J.; Simon, S.B.

1989-05-01

To study the effects of crystallization sequence and rate on trace element zoning characteristics of pyroxenes, the authors used combined electron microprobe-ion microprobe techniques on four nearly isochemical Apollo 12 and 15 pigeonite basalts with different cooling rates and crystallization histories. Major and minor element zoning characteristics are nearly identical to those reported in the literature. All the pyroxenes have similar chondrite-normalized REE patterns: negative Eu anomalies, positive slopes as defined by Yb/Ce, and slopes of REE patterns from Ce to Sm much steeper than from Gd to Yb. These trace element zoning characteristics in pyroxene and the partitioning ofmore » trace elements between pyroxene and the melt are intimately related to the interplay among the efficiency of the crystallization process, the kinetics at the crystal-melt interface, the kinetics of plagioclase nucleation and the characteristics of the crystal chemical substitutions within both the pyroxene and the associated crystallizing phases (i.e. plagioclase).« less

Quantification of diagenesis in Cenozoic sharks: Elemental and mineralogical changes

NASA Astrophysics Data System (ADS)

Labs-Hochstein, Joann; MacFadden, Bruce J.

2006-10-01

Diagenesis of bone during fossilization is pervasive, however, the extent of this process varies with depositional environment. This study quantifies diagenesis of shark vertebral centra through analysis of a suite of physical and chemical characters including crystallinty index (CI), carbonate content, and elemental concentrations. Although shark skeletons are initially cartilaginous, the soft cartilage of the vertebral centra is replaced with carbonate hydroxyapatite during growth. Nine vertebral centra are analyzed from lamnoid (Lamnoidea) sharks ranging in age from the cretaceous to recent using Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma mass spectrometry (ICPMS). The variables CI, carbonate content, rare earth element (REE) concentrations, Ca/P, Ba/Ca, Sr/Ba, (La/Yb) N, (La/Y) N, (La/Yb) N vs. (La/Sm) N, La/Yb, and Ce anomalies elucidate the diagenetic and depositional environments of the seven fossil vertebral centra. The two extant centra demonstrate the initial, unaltered end-member conditions for these variables. Two fossil vertebral centra ( Carcharodon megalodon and Isurus hastalis) demonstrate a strong terrestrial influence during diagenesis (distinctive flattening of shale-normalized REE patterns) that masked the seawater signal. Three centra ( Carcharodon auriculatus, Carcharodon angustidens, and Creotxyrhina mantelli) have indications of some terrestrial influx evident by some flattening of the REE patterns relative to seawater. The terrestrial influence in these five shark centra ( C. megalodon, I. hastalis, C. auriculatus, C. angustidens and C. mantelli) are interpreted to represent a primarily nearshore habitat for these species. In contrast, the two Otodus obliquus centra have REE patterns that represent the original seawater signal and have no indications of terrigenous input. These results indicate that fossil shark vertebral centra have the potential to understand diagenesis and reconstruct paleooceanographic environments.

Do Leached Authigenic Fractions Reflect the Neodymium Seawater Composition?

NASA Astrophysics Data System (ADS)

Pimbert, A.; Gourlan, A. T.; Chauvel, C.

2016-12-01

Leaching of marine sediment is often used to recover past Nd seawater composition and reconstruct past ocean circulation. It is assumed to reliably extract REE from the authigenic fraction of sediment [1]. However, while most studies assume that the recovered signal is that of past seawater, very few report complete isotopic and trace element data that clearly demonstrate it is the case. We present new ɛNd values and REE contents measured on leachates of sediments from two Cretaceous marine sections deposited at shallow water depth (Taghazoute in Morocco) and at greater depth in the Atlantic (DSDP Site 367). REE patterns of leachates vary according to lithology: bell-shaped patterns or positive Ce anomalies for organic-poor samples and seawater-like patterns (negative Ce anomaly, low Nd/Yb ratio) for black shales. ɛNd values also vary: between -5.6 and -9.6 at Taghazoute and between -10 and -8.1 at Site 367. Interestingly, ɛNd values correlate with Ce anomalies for Taghazoute black shales. Samples with the largest Ce negative anomalies have the highest ɛNd while samples with no Ce anomalies have much lower ɛNd. This suggests the presence in the leached material of detritus mixed up with the authigenic fraction for sediments deposited in shallow environment. This confirms the findings made by Huck et al. [2] for fish teeth in a similar environment. In such environment, recovering the pristine seawater signal requires (a) the acquisition of both Nd isotopes and trace element contents, and (b) selection of the only Nd isotopic compositions associated to clear seawater trace element characteristics. For sediments deposited in open-ocean setting (Site 367), no detrital contamination affects leached fractions. The REE patterns vary depending on the nature of authigenic fraction but ɛNd remains constant. Here, ɛNd values can be used to discuss oceanic reconstructions. [1] Martin et al. (2010), Chem. Geol, 269, 414-431. [2] Huck et al. (2016), G3, 17, 679-698.

Porites corals as recorders of mining and environmental impacts: Misima Island, Papua New Guinea

NASA Astrophysics Data System (ADS)

Fallon, Stewart J.; White, Jamie C.; McCulloch, Malcolm T.

2002-01-01

In 1989 open-cut gold mining commenced on Misima Island in Papua New Guinea (PNG). Open-cut mining by its nature causes a significant increase in sedimentation via the exposure of soils to the erosive forces of rain and runoff. This increased sedimentation affected the nearby fringing coral reef to varying degrees, ranging from coral mortality (smothering) to relatively minor short-term impacts. The sediment associated with the mining operation consists of weathered quartz feldspar, greenstone, and schist. These rocks have distinct chemical characteristics (rare earth element patterns and high abundances of manganese, zinc, and lead) and are entering the near-shore environment in considerably higher than normal concentrations. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we analyzed eight colonies (two from high sedimentation, two transitional, two minor, and two unaffected control sites) for Y, La, Ce, Mn, Zn, and Pb. All sites show low steady background levels prior to the commencement of mining in 1988. Subsequently, all sites apart from the control show dramatic increases of Y, La, and Ce associated with the increased sedimentation as well as rapid decreases following the cessation of mining. The elements Zn and Pb exhibit a different behavior, increasing in concentration after 1989 when ore processing began and one year after initial mining operations. Elevated levels of Zn and Pb in corals has continued well after the cessation of mining, indicating ongoing transport into the reef of these metals via sulfate-rich waters. Rare earth element (REE) abundance patterns measured in two corals show significant differences compared to Coral Sea seawater. The corals display enrichments in the light and middle REEs while the heavy REEs are depleted relative to the seawater pattern. This suggests that the nearshore seawater REE pattern is dominated by island sedimentation. Trace element abundances of Misima Island corals clearly record the dramatic changes in the environmental conditions at this site and provide a basis for identifying anthropogenic influences on corals reefs.

Non-CI refractory lithophile abundances in bulk planetary materials

NASA Astrophysics Data System (ADS)

Dauphas, N.

2015-12-01

Refractory inclusions in meteorites show evidence for fractionation of refractory lithophile elements relative to one another. For bulk planetary materials, it is most often assumed that refractory lithophile elements (e.g., Ca, Al, Ti, REEs) are in proportions similar to CI carbonaceous chondrites, which is taken to be a proxy for solar composition. A diagnostic feature of REE patterns in refractory inclusions in meteorites is the presence of thulium anomalies, arising from the fact that this heavy REE is more volatile than the highly refractory HREEs surrounding it (Tm/Tm* is defined relative to either Er-Yb or Er-Lu). Tm anomalies thus represent an excellent diagnostic tool to test the assumption that refractory lithophile elements have uniform relative abundances at a bulk planetary scale. Prior to this work, high precision Tm measurements were lacking because it is mono-isotopic and as such is not amenable to high-precision single spike measurements. We have developed a multi-collector REE abundance measurement technique to measure all REEs at high precision, including the mono-isotopic ones. This technique was used to revise the abundance of CI and PAAS REE abundances (Pourmand et al. 2012) and the CI composition agrees well with an independent study (Barrat et al. 2012). The same technique was applied to measure REE patterns in 41 chondrites as well as terrestrial rocks (Dauphas and Pourmand, 2015). Our results reveal the presence of Tm anomalies of about -4.5 % in terrestrial rocks, enstatite and ordinary chondrites, relative to carbonaceous chondrites including CIs. This demonstrates that the assumption that refractory lithophile elements are in constant proportions among planetary bodies is unwarranted. It also shows that carbonaceous chondrites cannot be a major constituent of the Earth. The presence of Tm anomalies in meteorites and terrestrial rocks suggests that either (i) the material in the inner part of the solar system was formed from a gas reservoir that had been depleted in refractory dust or (ii) CI are enriched in refractory dust and are not representative of solar composition for refractory elements. Barrat J.A. et al. (2012) GCA 83, 79-92. Dauphas N., Pourmand A. (2015) GCA 163, 234-261. Pourmand et al. (2012) Chem. Geol. 291, 38-54.

Audre's daughter: Black lesbian steganography in Dee Rees' Pariah and Audre Lorde's Zami: A New Spelling of My Name.

PubMed

Kang, Nancy

2016-01-01

This article argues that African-American director Dee Rees' critically acclaimed debut Pariah (2011) is a rewriting of lesbian poet-activist Audre Lorde's iconic "bio-mythography" Zami: A New Spelling of My Name (1982). The article examines how Rees' work creatively and subtly re-envisions Lorde's Zami by way of deeply rooted and often cleverly camouflaged patterns, resonances, and contrasts. Shared topics include naming, mother-daughter bonds, the role of clothing in identity formation, domestic abuse, queer time, and lesbian, gay, bisexual, and transgender legacy discourse construction. What emerges between the visual and written texts is a hidden language of connection--what may be termed Black lesbian steganography--which proves thought-provoking to viewers and readers alike.

The effect of the water-to-rock ratio on REE distribution in hydrothermal fluids: An experimental study

NASA Astrophysics Data System (ADS)

Beermann, Oliver; Garbe-Schönberg, Dieter; Holzheid, Astrid

2013-04-01

High-temperature submarine MOR hydrothermalism creates high elemental fluxes into, and out of, oceanic lithosphere significantly affecting ocean chemistry. The Turtle Pits hydrothermal system discovered at 5° S on the slow-spreading Mid-Atlantic Ridge (MAR) in water depths of ~3000 m (~300 bar) emanates 'ultrahot' fluids > 400 ° C [1] with high concentrations of dissolved gases (e.g., H2), transition metals, and rare earth elements (REE). The normalised REE patterns of these 'ultrahot' fluids are uncommon as they exhibit depletions of LREE and no Eu-anomaly ('special' REE-signature in [2]), which is in contrast to the "typical" LREE enrichment and pronounced positive Eu-anomaly known from many MOR vent fluids observed world-wide [e.g., 3]. Although hydrothermal fluid REE-signatures may play a key role in understanding processes during water-rock interaction, only few experimental data have been published on REE distribution in seawater-like fluids reacted with rocks from the ocean crust [e.g., 4, 5]. Besides temperature, the seawater-to-rock ratio (w/r ratio) strongly affects water-rock reaction processes and, thus, has significant control on the fluid chemistry [e.g., 6, 7]. To understand how vent fluid REE-signatures are generated during water-rock interaction processes we designed a series of experiments reacting different fluid types with mineral assemblages from fresh, unaltered gabbro at 425 ° C and 400 bar using cold seal pressure vessels (CSPV). Mixtures of 125-500 μm-sized hand-picked plagioclase and clinopyroxene grains separated from unaltered gabbro reacted in gold capsules with 3.2 wt.% NaCl(aq) fluid (similar to seawater salinity), or with natural seawater. The w/r (mass) ratio ranged from 1 to 100 and the run durations were varied from 3 to 30 d in the NaCl(aq) experiments, and was 3 d in the seawater experiments. The reacted fluids were extracted after quenching and analysed by ICP-OES and ICP-MS. Only in the seawater experiments, the gabbro reacted considerably with the liquid resulting in a strong REE enrichment relative to the original seawater. Increasing w/r ratios gave rise to decreasing pH of the quench fluid and enforced the enrichment of HREE in the fluid with relative depletion of LREE and no Eu-anomaly. The 'special' REE-signatures observed in Turtle Pits vent fluids at 5° S MAR could be reproduced in our experiments at a w/r ratio of 5 (pH = ~6), whereas at a w/r ratio of 1 (pH = ~7) the fluid exhibited the "typical" REE pattern with a positive Eu-anomaly. Fluids from experiments with w/r ratios ×10 (pH ~6 to ~2) showed higher HREE enrichment than observed in natural MOR vent fluids so far. Concluding, elevated REE concentrations in hydrothermal fluids exhibiting the 'special' REE pattern with relative enrichment of HREE and no Eu anomaly are indicative for leaching processes under high w/r ratios (~5-10) that might be more common in slow-spreading oceanic crust with focused hydrothermal fluid-flow along e.g., detachment faults [8]. References: [1] Koschinsky A., Garbe-Schönberg D., Sander S., Schmidt K., Gennerich H.-H., and Strauss H. (2008) Geology 36, 615-618. [2] Schmidt K., Garbe-Schönberg D., Bau M., and Koschinsky A. (2010) GCA 74, 4058-4077. [3] Douville E., Bienvenu P., Charlou J. L., Donval J. P., Fouquet Y., Appriou P., and Gamo T. (1999). GCA 63, 627-643. [4] You C.-F., Castillo P. R., Gieskes J. M., Chan L. H., and Spivak A. J. (1996) EPSL 140, 41-52. [5] Allen D. E. and Seyfried [Jr.] W. E.(2005) GCA 69, 675-683. [6] Seyfried [Jr.] W. E. and Bischoff J. L. (1977) EPSL 34, 71-77. [7] Hajash A. and Chandler G. W. (1981) Contrib Mineral Petrol 78, 240-254. [8] McCaig A.M. and Harris M. (2012) Geology 40, 367-370.

REE concentration processes in ion adsorption deposits: Evidence from Madagascar and China.

NASA Astrophysics Data System (ADS)

Smith, Martin; Estrade, Guillaume; Marquis, Eva; Goodenough, Kathryn; Nasun, Peter; Cheng, Xu; Kynicky, Jindrich

2017-04-01

Lateritic clay deposits, where the rare earth elements (REE) occur adsorbed to clay mineral surfaces, are the world's dominant supply of heavy REE (Gd-Lu). These deposits are currently only mined in China where there is a reported heavy REE enrichment, but other deposits are currently under exploration in Brazil, the Philippines and Madagascar. Concentration of REE within IADs has been proposed to be a dominantly supergene process, where easily degradable REE-minerals (e.g. REE-fluorcarbonates) break down and release REE that are then adsorbed to clay minerals resulting in HREE enrichment. Here we present data from the Ambohimirahavavy Complex, Madagascar, and compare them to data from mineralised profiles in China, with the aim of further constraining the formation and REE enrichment processes in ion adsorption deposits. Bulk rock total REE contents from Madagascar vary from 400-5000ppm, with the HREE varying from 10 to 20% of the TREE. Ammonium Sulphate leaches (designed to remove clay-adsorbed REE) of laterite show leachable TREE from 130-500ppm, with no preferential HREE adsorption. Within the sequential extraction procedure the reducible fraction (hydroxylammonium chloride leach) showed the highest REE, but this is largely attributable to Ce4+ in oxide layers. Analysis of laterite profiles show that the REE distribution is heterogeneous, with control from both bedrock heterogeneity, and the hydrological variation between pedolith and saprolith. Similar patterns are seen in Chinese profiles from Jiangxi province. X-ray diffraction shows the clay fraction in all sites is dominated by kaolinite and halloysite. These data are consistent with experimental data which show that kaolinite is only HREE selective in high ionic strength solutions (Coppin et al., 2002), and suggest that HREE enrichment in lateritic deposits may be a function of exceptional bed rock conditions. Petrographic investigation of the Zhaibei granite, immediately underlying HREE enriched weathering profiles in Jiangxi province has identified the presence of HREE-enriched secondary phases associated with carbonate-rich areas (Xu et al., In press). Neodymium isotope data from primary granitic minerals (ɛNd(t)=-11.5±0.5) contrasts dramatically with data from HREE-enriched minerals (ɛNd(t)=0.9±0.8) indicating that pre-weathering metasomatism from fluids derived from outside the granite system may be critical in the HREE enrichment process of mineralised laterites. This may be important in determining the viability of ion adsorption deposits as HREE resources. Coppin et al. (2002) Sorption of lanthanides on smectite and kaolinite. Chem. Geol. 182, 57-68 Xu et al., (In press) Origin of heavy rare earth mineralization in South China. Nature Comms.

Geochemistry of ferromanganese nodule-sediment pairs from Central Indian Ocean Basin

NASA Astrophysics Data System (ADS)

Pattan, J. N.; Parthiban, G.

2011-01-01

Fourteen ferromanganese nodule-sediment pairs from different sedimentary environments such as siliceous ooze (11), calcareous ooze (two) and red clay (one) from Central Indian Ocean Basin (CIOB) were analysed for major, trace and rare earth elements (REE) to understand the possible elemental relationship between them. Nodules from siliceous and calcareous ooze are diagenetic to early diagenetic whereas, nodule from red clay is of hydrogenetic origin. Si, Al and Ba are enriched in the sediments compared to associated nodules; K and Na are almost in the similar range in nodule-sediment pairs and Mn, Fe, Ti, Mg, P, Ni, Cu, Mo, Zn, Co, Pb, Sr, V, Y, Li and REEs are all enriched in nodules compared to associated sediments (siliceous and calcareous). Major portion of Si, Al and K in both nodules and sediments appear to be of terrigenous nature. The elements which are highly enriched in the nodules compared to associated sediments from both siliceous and calcareous ooze are Mo - (307, 273), Ni - (71, 125), Mn - (64, 87), Cu - (43, 80), Co - (23, 75), Pb - (15, 24), Zn - (9, 11) and V - (8, 19) respectively. These high enrichment ratios of elements could be due to effective diagenetic supply of metals from the underlying sediment to the nodule. Enrichment ratios of transition metals and REEs in the nodule to sediment are higher in CIOB compared to Pacific and Atlantic Ocean. Nodule from red clay, exhibit very small enrichment ratio of four with Mn and Ce while, Al, Fe, Ti, Ca, Na, K, Mg, P, Zn, Co, V, Y and REE are all enriched in red clay compared to associated nodule. This is probably due to presence of abundant smectite, fish teeth, micronodules and phillipsite in the red clay. The strong positive correlation ( r ⩾ 0.8) of Mn with Ni, Cu, Zn and Mo and a convex pattern of shale-normalized REE pattern with positive Ce-anomaly of siliceous ooze could be due to presence of abundant manganese micronodules. None of the major trace and REE exhibits any type of inter-elemental relationship between nodule and sediment pairs. Therefore, it may not be appropriate to correlate elemental behaviour between these pairs.

Aegirine-melt element partitioning and implications for the formation of nepheline syenite REE deposits

NASA Astrophysics Data System (ADS)

Beard, Charles; van Hinsberg, Vincent; Stix, John; Wilke, Max

2017-04-01

Sodic clinopyroxene is a key fractionating phase in alkaline magmatic systems but its impact on metal enrichment processes, and the formation of REE + HFSE mineralizations in particular, is not fully understood. Sodic pyroxenes appear to more readily incorporate REE than their calcic equivalents1. Despite this, melts in evolved alkaline systems can attain high REE contents, even up to economic levels (e.g. the Nechalacho layered suite in Canada2). To constrain the control of pyroxene on REE + HFSE behaviour in alkaline magmas, a series of internally heated pressure vessel experiments was performed to determine pyroxene-melt element partitioning systematics. Synthetic trachy-andesite to phonolite compositions were run water saturated at 650-825°C with fO2 buffered by ca. 1 bar of H2 (QFM + 1) or by Hm-Mt (QFM +5). Fluorine was added to selected experiments (0.3 to 2.5 wt %) to ascertain its effect on element partitioning. Run products were analysed by EMP for major elements and LA-ICP-MS for trace elements. Mineral and glass compositions bracket the compositions of natural alkaline systems, allowing for direct application of our experimental results to nature. Our results indicate that REE partitioning systematics vary strongly with pyroxene composition: Diopside-rich pyroxenes (Aeg5-25) prefer the MREE, medium aegirine pyroxenes (Aeg25-50) preferentially incorporate the LREE, whereas high aegirine pyroxenes (Aeg55-95) strongly prefer HREE. REE partitioning coefficients are 0.3-40, typically 2-6, with minima for high aegirine pyroxenes. Melt composition (e.g. (Na+K)/Al) also impacts partitioning although to a lesser extent, except for the F-content, which shows no impact at all. The composition of fractionating pyroxene has a major impact on the REE pattern of the residual melt, and thus on the ability of a system to develop economic concentrations of the REE. Element partitioning systematics suggest that late-crystallising aegirine-rich cumulates would be HREE-rich, in accord with the composition of mineralised intrusions, such as Nechalacho2. 1 - Marks, M., Halama, R., Wenzel, T. & Markl, G., 2004. Chem. Geol. 211, 185-215. 2 - Möller, V. & Williams-Jones, A. E., 2016. J. Petrology 57, 229-276.

[Geochemical characteristics and sources of atmospheric particulates in Shanghai during dust storm event].

PubMed

Qian, Peng; Zheng, Xiang-min; Zhou, Li-min

2013-05-01

Atmospheric particulates were sampled from three sampling sites of Putuo, Minhang and Qingpu Districts in Shanghai between Oct. , 2009 and Oct. , 2010. In addition, particulate samples were also collected from Nantong, Zhengzhou, Xi'an, and Beijing city where dust storm dust transported along during spring. Element compositions of atmospheric particulates were determined by XRF and ICP-MS. The concentrations of major and trace elements in atmospheric particulates from Putuo, Minhang and Qingpu Districts were similar, indicating their common source. The UCC standardization distribution map showed that the major element composition of dust storm samples was similar to that of loess in northwestern China, indicating that the dust storm dust was mainly derived from Western desert and partly from local area. The REE partition patterns of dust storm dusts among different cities along dust transport route were similar to each other, as well as to those of northern loess, which indicates that the dust storm samples may have the same material source as loess, which mainly comes from crust material. However, the REE partition patterns of non-dust storm particulates were different among the studied cities, and different from those of loess, which suggests that the non-dust storm samples may be mixed with non-crust source material, which is different from dust storm dust and loess. The major element composition and REE partition pattern are effective indicators for source tracing of dust storm dust.

Magmatic geochemistry and relict textures in blueschist-eclogite facies rocks on the island of Syros, Greece

NASA Astrophysics Data System (ADS)

Schumacher, J. C.; Brady, J. B.; Prinkey, D. R.; Walton, A. J.; Able, L. M.; Sinitsin, A. G.; Cheney, J. T.

2004-05-01

The island of Syros is part of the Attic-Cycladic blueschist belt and high-P mineral assemblages indicating peak metamorphic conditions of at least 15-16 kbar and 500 C are common. Two main marble units, which locally contain Mississippian fossils, are partly dolomitic, contain abundant calcite pseudomorphs after aragonite (Dixon, 1969), and are intercalated with the glaucophane (Glau)-schists, retrograde greenschists, and minor quartzites and Mn-cherts. Discrete, fault-bounded packages of blueschist/eclogite-facies mafic rocks with minor serpentinite are also present. The mineral compositions and assemblages in marbles and associated rocks tightly constrain the metamorphic P, T and the fluid compositions and suggest X(H2O) in the range 0.97-0.99. In general, the mafic rocks have a variety of textures and modes, but most are either fine-grained, blueschists with a well-developed fabric (S approx.=L) or coarse-grained (>1 cm), massive omphacite- or Glau-rich rocks. Based on textures, mineralogy and field relations, previous workers (Dixon and Ridley, 1987) have interpreted the mafic rocks as meta-basalt and metagabbros. Evidence of pillow structures, as well as metamorphosed alteration zones which are interpreted as evidence of ocean-floor metamorphism (?) have survived locally. We obtained whole-rock XRF and INAA analyses for fine- and coarse-grained mafic and felsic rocks and some mica-rich samples. Low chemical index of alteration (CIA) for most samples suggest very minor weathering. On a TAS diagram, mafic rocks span the basalt - basaltic andesite - trachy-basalt - basaltic trachy-andesite fields. REE patterns generally fall between 10-100 times chondrite and show flat to moderately LREE-enriched patterns. Coarse-grained rocks have positive Eu anomalies, consistent with their interpretation by other investigators as fractionally crystallized gabbros. Felsic rocks (now epidote-mica-schists) that are associated with the metamorphosed gabbros have negative Eu anomalies, and modeling of the REEs suggests that the felsic rocks represent residual melts during the crystallization of the gabbros. The low CIA-values indicate that the mica-schist precursors lacked significant clay material. The presence of abundant epidote (Zo) is consistent with a feldspar-rich (magmatic) protolith for the mica-schists.

Rare Earth Elements of the Permian-Triassic Conodonts from Shelf Basin to Shallow Platform: Implications for Oceanic Redox Conditions immediately After the End-Permian Mass Extinction

NASA Astrophysics Data System (ADS)

Li, Y.; Zhao, L.; Chen, Z.; Chen, J.; Chen, Y.

2013-12-01

Rare-earth elements (REEs) can provide information regarding the influence of weathering fluxes and hydrothermal inputs on seawater chemistry as well as processes that fractionate REEs between solid and aqueous phases. Of these, cerium (Ce) distributions may provide information about variations in dissolved oxygen in seawater, and thus assess the redox conditions. The short residence times of REEs in seawater (~300-1,000 yr) can result in unique REE signatures in local watermasses. REE patterns preserved in biogenic apatite such as conodonts are ideal proxies for revealing original seawater chemistry. Here, we measured the REE content of in-situ, single albid crowns using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in combination with an ArF (λ=193 nm) excimer laser (Lambda Physiks GeoLas 2005) and quadrupole ICP-MS (Agilent 7500a). LA-ICP-MS is ideally suited for analyzing conodonts due to its ability to measure compositional variation within single conodont elements. It has the capability to determine, with high spatial resolution, continuous compositional depth profiles through the concentric layered structure of component histologies. To evaluate paleoceanographic conditions immediately after the Permian-Triassic (P-Tr) mass extinction in various depositional settings, we sampled a nearly contemporaneous strata unit, the P-Tr boundary bed, just above the extinction horizon from six sections in South China. They represent various depositional settings from shelf basin (Chaohu and Daxiakou sections), lower part of ramp (Meishan section), normal shallow platform (Yangou section), and platform microbialite (Chongyang and Xiushui sections). The sampled unit is constrained by conodonts Hindeodus changxingensis, H. parvus, and H. staeschei Zones in Meishan. REE results obtained from conodont albid crowns show that the seawater in lower ramp and shelf basin settings contains much higher REE concentrations than that in shallow platform. Ce/Ce* ratios in shelf basin and lower ramp are similar to one another, ranging from 0.7-1.0. The same ratios, however, are much lower in shallow platform and microbialite settings, ranging from 0.17-0.22 and 0.2-0.45, respectively. Eu/Eu+ ratios also show similar patterns: 0.7-1.0 in shelf basin and lower ramp and 0.3-0.7 in shallow platform. If the Ce/Ce* was truly influenced by environmental redox conditions, then Ce/Ce* values of 0.7-1.0 in shelf basin and lower ramp settings are indicative of a suboxic to anoxic depositional system, while the same proxy of 0.17-0.45 in shallow platform and microbialite points to a well-oxygenated setting immediately after the P-Tr mass extinction.

Major, trace and REE geochemistry of recent sediments from lower Catumbela River (Angola)

NASA Astrophysics Data System (ADS)

Vinha, Manuela; Silva, M. G.; Cabral Pinto, Marina M. S.; Carvalho, Paula Cristina S.

2016-03-01

The mineralogy, texture, major, trace and rare earth elements, from recent sediment samples collected in the lower Catumbela River, were analysed in this study to characterize and discuss the factors controlling its geochemistry and provide data that can be used as tracers of Catumbela River inputs to the Angolan continental shelf. The sediments are mainly sands and silty-sands, but sandy-silt also occurs and the mineralogy is composed of quartz, feldspar, phyllosilicates, magnetite, ilmenite and also carbonates when the river crosses limestones and marls in the downstream sector. The hydraulic sorting originates magnetite-ilmenite and REE-enriched minerals placers. The mineralogy of the sediments is controlled by the source rocks and the degree of chemical weathering is lower than erosion. The texture is mainly controlled by location. There is enrichment in all the analysed trace elements in the fine grained, clay minerals and Fe-oxy-hydroxides rich sediments, compared to the coarse grained and quartz plus feldspar rich ones. The coarse grained sediments (without the placers) are impoverished in ΣREE when compared with UCC and NASC compositions, while the fine grained sediments have ΣREE contents similar to UCC and NASC. The placers have ΣREE contents up to 959.59 mg/kg. The source composition is the dominant factor controlling the REE geochemistry of the analysed sediments as there is no difference in the (La/Yb)N, (La/Sm)N and (Gd/Yb)N ratios in coarse and fine grained sediments. The sorting of magnetite, ilmenite, zircon, throrite, thorianite, rutile and titanite explain the HREE/LREE enriched patterns of the coarse grained sediments.

Sediment Sources, Depositional Environment, and Diagenetic Alteration of the Marcellus Shale, Appalachian Basin, USA: Nd, Sr, Li and U Isotopic Constraints

NASA Astrophysics Data System (ADS)

Phan, T. T.; Capo, R. C.; Gardiner, J. B.; Stewart, B. W.

2017-12-01

The organic-rich Middle Devonian Marcellus Shale in the Appalachian Basin, eastern USA, is a major target of natural gas exploration. Constraints on local and regional sediment sources, depositional environments, and post-depositional processes are essential for understanding the evolution of the basin. In this study, multiple proxies, including trace metals, rare earth elements (REE), the Sm-Nd and Rb-Sr isotope systems, and U and Li isotopes were applied to bulk rocks and authigenic fractions of the Marcellus Shale and adjacent limestone/sandstone units from two locations separated by 400 km. The range of ɛNd values (-7.8 to -6.4 at 390 Ma) is consistent with a clastic sedimentary component derived from a well-mixed source of fluvial and eolian material of the Grenville orogenic belt. The Sm-Nd isotope system and bulk REE distributions appear to have been minimally affected by post-depositional processes, while the Rb-Sr isotope system shows evidence of limited post-depositional redistribution. While REE are primarily associated with silicate minerals (80-95%), REE patterns of sequentially extracted fractions reflect post-depositional alteration at the intergranular scale. Although the chemical index of alteration (CIA = 54 to 60) suggests the sediment source was not heavily weathered, Li isotope data are consistent with progressively increasing weathering of the source region during Marcellus Shale deposition. δ238U values in bulk shale and reduced phases (oxidizable fraction) are higher than those of modern seawater and upper crust. The isotopically heavy U accumulated in these authigenic phases can be explained by the precipitation of insoluble U in anoxic/euxinic bottom water. Unlike carbonate cement within the shale, the similarity between δ238U values and REE patterns of the limestone units and those of modern seawater indicates that the limestone formed under open ocean (oxic) conditions.

Aqueous stability of gadolinium in surface waters receiving sewage treatment plant effluent Boulder Creek, Colorado

USGS Publications Warehouse

Verplanck, P.L.; Taylor, Howard E.; Nordstrom, D. Kirk; Barber, L.B.

2005-01-01

In many surface waters, sewage treatment plant (STP) effluent is a substantial source of both regulated and unregulated contaminants, including a suite of complex organic compounds derived from household chemicals, pharmaceutical, and industrial and medical byproducts. In addition, STP effluents in some urban areas have also been shown to have a positive gadolinium (Gd) anomaly in the rare earth element (REE) pattern, with the Gd derived from its use in medical facilities. REE concentrations are relatively easy to measure compared to many organic wastewater compounds and may provide a more widely utilized tracer of STP effluents. To evaluate whether sewage treatment plant-associated Gd is a useful tracer of treatment plant effluent, an investigation of the occurrence, fate, and transport of rare earth elements was undertaken. The rare earth element patterns of four of five STP effluents sampled display positive Gd anomalies. The one site that did not have a Gd anomaly serves a small community, population 1200, with no medical facilities. Biosolids from a large metropolitan STP are not enriched in Gd even though the effluent is, suggesting that a substantial fraction of Gd remains in the aqueous phase through routine treatment plant operation. To evaluate whether STP-derived Gd persists in the fluvial environment, a 14-km study reach downstream of an STP was sampled. Gadolinium anomalies were present at all five downstream sites, but the magnitude of the anomaly decreased. Effluent from STPs is a complex mixture of organic and inorganic constituents, and to better understand the chemical interactions and their effect on REEs, the aqueous speciation was modeled using comprehensive chemical analyses of water samples collected downstream of STP input. These calculations suggest that the REEs will likely remain dissolved because phosphate and carbonate complexes dominate over free REE ions. This study supports the application of Gd anomalies as a useful tracer of urban wastewater.

Aqueous stability of gadolinium in surface waters receiving sewage treatment plant effluent, Boulder Creek, Colorado.

PubMed

Verplanck, Philip L; Taylor, Howard E; Nordstrom, D Kirk; Barber, Larry B

2005-09-15

In many surface waters, sewage treatment plant (STP) effluent is a substantial source of both regulated and unregulated contaminants, including a suite of complex organic compounds derived from household chemicals, pharmaceuticals, and industrial and medical byproducts. In addition, STP effluents in some urban areas have also been shown to have a positive gadolinium (Gd) anomaly in the rare earth element (REE) pattern, with the Gd derived from its use in medical facilities. REE concentrations are relatively easy to measure compared to many organic wastewater compounds and may provide a more widely utilized tracer of STP effluents. To evaluate whether sewage treatment plant-associated Gd is a useful tracer of treatment plant effluent, an investigation of the occurrence, fate, and transport of rare earth elements was undertaken. The rare earth element patterns of four of five STP effluents sampled display positive Gd anomalies. The one site that did not have a Gd anomaly serves a small community, population 1200, with no medical facilities. Biosolids from a large metropolitan STP are not enriched in Gd even though the effluent is, suggesting that a substantial fraction of Gd remains in the aqueous phase through routine treatment plant operation. To evaluate whether STP-derived Gd persists in the fluvial environment, a 14-km study reach downstream of an STP was sampled. Gadolinium anomalies were present at all five downstream sites, but the magnitude of the anomaly decreased. Effluent from STPs is a complex mixture of organic and inorganic constituents, and to better understand the chemical interactions and their effect on REEs, the aqueous speciation was modeled using comprehensive chemical analyses of water samples collected downstream of STP input. These calculations suggest that the REEs will likely remain dissolved because phosphate and carbonate complexes dominate over free REE ions. This study supports the application of Gd anomalies as a useful tracer of urban wastewater.

The use of decision tree induction and artificial neural networks for recognizing the geochemical distribution patterns of LREE in the Choghart deposit, Central Iran

NASA Astrophysics Data System (ADS)

Zaremotlagh, S.; Hezarkhani, A.

2017-04-01

Some evidences of rare earth elements (REE) concentrations are found in iron oxide-apatite (IOA) deposits which are located in Central Iranian microcontinent. There are many unsolved problems about the origin and metallogenesis of IOA deposits in this district. Although it is considered that felsic magmatism and mineralization were simultaneous in the district, interaction of multi-stage hydrothermal-magmatic processes within the Early Cambrian volcano-sedimentary sequence probably caused some epigenetic mineralizations. Secondary geological processes (e.g., multi-stage mineralization, alteration, and weathering) have affected on variations of major elements and possible redistribution of REE in IOA deposits. Hence, the geochemical behaviors and distribution patterns of REE are expected to be complicated in different zones of these deposits. The aim of this paper is recognizing LREE distribution patterns based on whole-rock chemical compositions and automatic discovery of their geochemical rules. For this purpose, the pattern recognition techniques including decision tree and neural network were applied on a high-dimensional geochemical dataset from Choghart IOA deposit. Because some data features were irrelevant or redundant in recognizing the distribution patterns of each LREE, a greedy attribute subset selection technique was employed to select the best subset of predictors used in classification tasks. The decision trees (CART algorithm) were pruned optimally to more accurately categorize independent test data than unpruned ones. The most effective classification rules were extracted from the pruned tree to describe the meaningful relationships between the predictors and different concentrations of LREE. A feed-forward artificial neural network was also applied to reliably predict the influence of various rock compositions on the spatial distribution patterns of LREE with a better performance than the decision tree induction. The findings of this study could be effectively used to visualize the LREE distribution patterns as geochemical maps.

Cytokines and metabolic patterns in pediatric patients with critical illness.

PubMed

Briassoulis, George; Venkataraman, Shekhar; Thompson, Ann

2010-01-01

It is not known if cytokines, which are cell-derived mediators released during the host immune response to stress, affect metabolic response to stress during critical illness. The aim of this prospective study was to determine whether the metabolic response to stress is related to the inflammatory interleukin-6 (IL-6), 10 (IL-10), and other stress mediators' responses and to assess their relationships with different feeding patterns, nutritional markers, the severity of illness as assessed by the Multiple Organ System Failure (MOSF), the Pediatric Risk of Mortality Score (PRISM), systemic inflammatory response syndrome (SIRS), and mortality in critically ill children. Patients were classified as hypermetabolic, normometabolic, and hypometabolic when the measured resting energy expenditures (REE) were >110%, 90-110% and, <90% of the predicted basal metabolic rate, respectively. The initial predominance of the hypometabolic pattern (48.6%) declined within 1 week of acute stress (20%), and the hypermetabolic patterns dominated only after 2 weeks (60%). Only oxygen consumption (VO(2)) and carbon dioxide production (VCO(2)) (P < .0001) but none of the cytokines and nutritional markers, were independently associated with a hypometabolic pattern. REE correlated with the IL-10 but not PRISM. In the presence of SIRS or sepsis, CRP, IL-6, IL-10, Prognostic Inflammatory and Nutritional Index (NI), and triglycerides--but not glucose, VO(2), or VCO(2) increased significantly. High IL-10 levels (P = .0000) and low measured REE (P = .0000) were independently associated with mortality (11.7%), which was higher in the hypometabolic compared to other metabolic patterns (P < .005). Our results showed that only VO(2) and VCO(2), but not IL-6 or IL-10, were associated with a hypometabolic pattern which predominated the acute phase of stress, and was associated with increased mortality. Although in SIRS or sepsis, the cytokine response was reliably reflected by increases in NI and triglycerides, it was different from the metabolic (VO(2), VCO(2)) or glucose response.

Cytokines and Metabolic Patterns in Pediatric Patients with Critical Illness

PubMed Central

Briassoulis, George; Venkataraman, Shekhar; Thompson, Ann

2010-01-01

It is not known if cytokines, which are cell-derived mediators released during the host immune response to stress, affect metabolic response to stress during critical illness. The aim of this prospective study was to determine whether the metabolic response to stress is related to the inflammatory interleukin-6 (IL-6), 10 (IL-10), and other stress mediators' responses and to assess their relationships with different feeding patterns, nutritional markers, the severity of illness as assessed by the Multiple Organ System Failure (MOSF), the Pediatric Risk of Mortality Score (PRISM), systemic inflammatory response syndrome (SIRS), and mortality in critically ill children. Patients were classified as hypermetabolic, normometabolic, and hypometabolic when the measured resting energy expenditures (REE) were >110%, 90–110% and, <90% of the predicted basal metabolic rate, respectively. The initial predominance of the hypometabolic pattern (48.6%) declined within 1 week of acute stress (20%), and the hypermetabolic patterns dominated only after 2 weeks (60%). Only oxygen consumption (VO2) and carbon dioxide production (VCO2) (P < .0001) but none of the cytokines and nutritional markers, were independently associated with a hypometabolic pattern. REE correlated with the IL-10 but not PRISM. In the presence of SIRS or sepsis, CRP, IL-6, IL-10, Prognostic Inflammatory and Nutritional Index (NI), and triglycerides—but not glucose, VO2, or VCO2 increased significantly. High IL-10 levels (P = .0000) and low measured REE (P = .0000) were independently associated with mortality (11.7%), which was higher in the hypometabolic compared to other metabolic patterns (P < .005). Our results showed that only VO2 and VCO2, but not IL-6 or IL-10, were associated with a hypometabolic pattern which predominated the acute phase of stress, and was associated with increased mortality. Although in SIRS or sepsis, the cytokine response was reliably reflected by increases in NI and triglycerides, it was different from the metabolic (VO2, VCO2) or glucose response. PMID:20490277

Evaluation of carbonate diagenesis: A comparative study of minor elements, trace elements, and rare-earth elements (REE + Y) between Pleistocene corals and matrices from Grand Cayman, British West Indies

NASA Astrophysics Data System (ADS)

Li, Rong; Jones, Brian

2014-12-01

On Grand Cayman, the Pleistocene Ironshore Formation consists of six unconformity-bounded units of limestones that have been partially or completely altered to calcite by post-depositional meteoric diagenesis. In order to examine the diagenetic history from the perspective of geochemical elements, the concentrations of minor element (Sr, Na, Mg), trace elements (Ba, Fe, Mn, Al, Si), and rare-earth elements (REE) and yttrium (Y) were determined for 105 corals and 84 matrices collected from the Rogers Wreck Point (RWP), Western Onshore area (WO), and offshore George Town (GT) areas. With the transformation of aragonite to calcite, the Sr, Na, and Ba values decreased, but Mg increased, which are indicative of diagenetic alteration in an open water system. Due to intrinsic "vital effects" and the extrinsic diagenetic environment, the variations of Sr, Na, Ba, and Mg concentrations between Acropora and Montastrea from the GT area are different to those of their counterparts from RWP and WO. The signatures of Sr, Na, Ba, and Mg are in good agreement with the diagenetic history as determined from petrographic and stable isotopic criteria. The REE + Y (REY) concentrations (ΣREY) are higher in the matrices (0.2-6.9 ppm, average 2.6 ppm) than in the associated corals (0.1-5.4 ppm, average 0.6 ppm). Shale-normalized REY patterns of the Pleistocene Ironshore Formation are similar to those of oxygenated seawater, which are characterized by (1) light REE depletion relative to heavy REE (average DySN/SmSN = 1.7, n = 35), (2) positive La anomalies (average Pr/Pr* = 1.17, n = 53), and (3) negative Ce anomalies (average Ce/Ce* = 0.49, n = 53). The preserved seawater-like REY distribution pattern, the lack of correlation between ΣREY and mineralogy, and the lack of correlation between ΣREY and diagenesis-sensitive stable oxygen isotope (δ18O) indicate that meteoric diagenesis did not have a major impact on the REY distribution patterns. The matrices and corals in the GT area, compared to their counterparts from RWP and WO, have relatively less depleted LREE and lower Y in REY distribution pattern, suggesting contamination by minor amounts of detrital sediments. This is supported by the fact that limestones from the GT area contain abnormally high contents of detrital elements (Al, Si). The variations in ΣREY in carbonate rocks from locality to locality probably reflect variations that existed in the local depositional environments where these deposits originally formed.

Hydrothermal barite mineralization at Chenarvardeh deposit, Markazi Province, Iran: Evidences from REE geochemistry and fluid inclusions

NASA Astrophysics Data System (ADS)

Ehya, Farhad; Mazraei, Shaghayegh Moalaye

2017-10-01

Barite mineralization occurs at Chenarvardeh deposit as layers and lenses in Upper Eocene volcanic and pyroclastic rocks. The host rocks are intensely saussuritized in most places. Barite is accompanied by calcite, Mn-oxides, galena and malachite as subordinate minerals. The amount of Sr in barites is low and varies between 0.11 and 0.30 wt%. The concentration of Rb, Zr, Y, Ta and Hf is also low (<5 ppm) in barite samples. The amount of total REEs (∑REE) is low in barites, ranging from 7.51 to 30.50 ppm. Chondrite-normalized REE patterns reveal LREE enrichment with respect to HREE, and positive Ce anomalies. Fluid inclusions are common in barite samples, being dominantly from liquid-rich two phase (L + V) type. Salinity values in fluid inclusions range from 9.41 to 18.69 wt% NaCl equivalent with most frequent salinities falling in the range of 10-15 wt% NaCl equivalent. Homogenization temperatures (Th) range between 160 and 220 °C, being the 180-200 °C range as the most common Th interval. A combination of factors, including geologic setting, host rock, mineral assemblages, REE geochemistry and fluid inclusion data are consistent with a submarine volcanic hydrothermal model for barite formation at the Chenarvardeh deposit. Mineral-forming fluids originated from solutions related to submarine hydrothermal activities deposited barite on seafloor as they encountered sulfate-bearing seawater.

Dissolved indium and rare earth elements in three Japanese rivers and Tokyo Bay: Evidence for anthropogenic Gd and In

NASA Astrophysics Data System (ADS)

Nozaki, Yoshiyuki; Lerche, Dorte; Alibo, Dia Sotto; Tsutsumi, Makoto

2000-12-01

New data on the dissolved (<0.04 μm) rare earth elements (REEs) and In in the Japanese Ara, Tama, and Tone river-estuaries and Tokyo Bay are presented. Unique shale-normalized REE patterns with a distinct positive Gd anomalies and a strong heavy-REE enrichment were seen throughout the data. The dissolved Gd anomaly is caused by local anthropogenic input mainly due to recent use of Gado-pentetic acid as a medical agent for magnetic resonance imaging (MRI) in hospitals. The heavy-REE enrichment may be attributed to fractionation during weathering and transport in the upstream of the rivers, and only partially to removal of light- and middle-REE enriched river colloids by the use of a new ultrafiltration technique. Dissolved In concentrations in the Japanese rivers are extraordinarily high as compared to those in the pristine Chao Phraya river of Thailand reported elsewhere (Nozaki et al., in press). Like Gd, the high dissolved In in the study area can also be ascribed to recent use of In-containing organic compound, In(DTPA) 2- in medical diagnosis. Thus, in the highly populated and industrialized area, dissolved heavy metal concentrations in rivers and estuaries may be significantly perturbed by human activities and the fate of those anthropogenic soluble substances in the marine environment needs to be investigated further.

Robustness of fossil fish teeth for seawater neodymium isotope reconstructions under variable redox conditions in an ancient shallow marine setting

NASA Astrophysics Data System (ADS)

Huck, Claire E.; van de Flierdt, Tina; Jiménez-Espejo, Francisco J.; Bohaty, Steven M.; Röhl, Ursula; Hammond, Samantha J.

2016-03-01

Fossil fish teeth from pelagic open ocean settings are considered a robust archive for preserving the neodymium (Nd) isotopic composition of ancient seawater. However, using fossil fish teeth as an archive to reconstruct seawater Nd isotopic compositions in different sedimentary redox environments and in terrigenous-dominated, shallow marine settings is less proven. To address these uncertainties, fish tooth and sediment samples from a middle Eocene section deposited proximal to the East Antarctic margin at Integrated Ocean Drilling Program Site U1356 were analyzed for major and trace element geochemistry, and Nd isotopes. Major and trace element analyses of the sediments reveal changing redox conditions throughout deposition in a shallow marine environment. However, variations in the Nd isotopic composition and rare earth element (REE) patterns of the associated fish teeth do not correspond to redox changes in the sediments. REE patterns in fish teeth at Site U1356 carry a typical mid-REE-enriched signature. However, a consistently positive Ce anomaly marks a deviation from a pure authigenic origin of REEs to the fish tooth. Neodymium isotopic compositions of cleaned and uncleaned fish teeth fall between modern seawater and local sediments and hence could be authigenic in nature, but could also be influenced by sedimentary fluxes. We conclude that the fossil fish tooth Nd isotope proxy is not sensitive to moderate changes in pore water oxygenation. However, combined studies on sediments, pore waters, fish teeth, and seawater are needed to fully understand processes driving the reconstructed signature from shallow marine sections in proximity to continental sources.

Sphene (Titanite) as Both Monitor and Driver of Evolution of Felsic Magma: Miocene Volcanic Plutonic and Rocks of the Colorado River Region, NV-AZ, USA

NASA Astrophysics Data System (ADS)

Miller, C. F.; Colombini, L. L.; Wooden, J. L.; Mazdab, F. K.; Gualda, G. A.; Claiborne, L. E.; Ayers, J. C.

2009-05-01

Sphene is commonly the most abundant accessory mineral in metaluminous to weakly peraluminous igneous rocks. Its relatively large crystals preserve a wide array of zoning patterns and inclusions - notably, abundant other accessories and melt inclusions - and it is a major host for REE, U, Th, and HFSE. Thus it is a valuable repository of information about the history of the magmas from which it forms. Recent development of a Zr-in- sphene thermometer (Hayden et al CMP 155:529 2008) and of sensitive and precise in situ trace element analysis by SHRIMP-RG (Mazdab et al GSA abst 39:6:406 2007) permit more powerful exploitation of this repository. We have initiated a study of sphene in Miocene intrusive and extrusive rocks of the Colorado River extensional corridor for which extensive field, geochemical, and geochronological data provide context. Sphene is present as a late interstitial phase in some gabbros and diorites and common in quartz monzonites and granites. Among extrusive rocks, it occurs as phenocrysts in rhyolite lavas and tuffs that are products of small to giant eruptions (Peach Spring Tuff, >600 km3). Glasses that host sphene in the rhyolites are highly evolved (>76 wt% SiO2). Applying the Zr-in-sphene thermometer (TZr), SHRIMP-RG analyses indicate crystallization T between 730 and 810 C in both plutonic and volcanic rocks. This range is narrower than T estimates for zircon growth (Ti thermometry) for the same suite, which extend to somewhat lower and considerably higher values; zircons also tend to record more events and, evidently, longer histories. Ranges of REE patterns are variable and to some extent sample-specific, but all reveal common characteristics: (1) extremely high concentrations, especially for middle REE (maximum Sm in interiors 10-40x103 x chondrite); (2) deep negative Eu anomalies (Eu/Eu* ca. 0.1-0.2); (3) TZr and REE dropping toward rims - especially pronounced for MREE. Estimated Kds for REE from sphene rims and rhyolite glass or phenocryst- poor whole rocks are very high, especially for middle REE: LREE Kds ca. 50-100, MREE ~500-600 (Eu ca. 300- 400), HREE ca. 100. Late REE fractionation trends that are evident in both plutonic and volcanic sequences are clearly controlled for the most part by sphene: aplites, some leucogranites, and high-Si rhyolite whole rocks and glasses reveal extreme MREE depletion and suppressed development of Eu anomalies, a trend that is also expressed in core-to-rim REE depletion patterns in sphene crystals. Results suggest that sphene saturation in these magmas occurred in melts that were already evolved but that it had a dramatic effect on final stages of fractionation. The sphene 'fingerprint' is similar to that proposed by Glazner et al. (Geology 36:183 2008) for Sierra Nevada aplites and as they suggest it marks a late-stage process, but in contrast to their inference we demonstrate that it is evident in volcanic as well as comagmatic plutonic rocks. A better understanding of the controls of sphene saturation will lead to refined interpretation of its presence (or absence), onset of growth, and geochemical fingerprint with respect to magmatic-tectonic environments (cf. Bachmann & Bergantz JPet 49:2277 2008). We intend to address these issues further with saturation experiments and tomographic and geochemical studies of sphene and its inclusions and associated phases.

Lanthanide, yttrium, and zirconium anomalies in the Fire Clay coal bed, Eastern Kentucky

USGS Publications Warehouse

Hower, J.C.; Ruppert, L.F.; Eble, C.F.

1999-01-01

The Fire Clay coal bed in the Central Appalachian basin region contains a laterally-persistent tonstein that is found in the coal throughout most of its areal extent. The tonstein contains an array of minerals, including sanidine, ??-quartz, anatase and euhedral zircon, thhat constitutes strong evidence for a volcanic origin of the parting. For this study, five samples of the tonstein and four sets of coal samples underlying the tonstein were collected from five sites in eastern Kentucky. Inductively coupled plasma-mass spectroscopy (ICP-MS) analysis of the tonstein and underlying coal collected from four sites in eastern Kentucky show that although Zr concentrations are high in the tonstein (570-1820 ppm on a coal-ash basis (cab)), they are highest in the coal directly underlying the tonstein (2870-4540 ppm (cab)). A similar enrichment pattern is observed in the concentration of Y plus the sum of the rare earth elements (Y + ??REE): total Y + ??REE concentrations in the five tonstein samples range from 511 to 565 ppm (cab). However, Y + ??REE contents are highest in the coals directly underlying the tonsteins: values range from 1965 to 4198 ppm (cab). Scanning electron microscopy of samples from coal which directly underlies two of the tonstein samples show that REE-rich phosphate, tentatively identified as monazite, commonly infills cracks in clays and cells in clarain and vitrain. Zircon is rare and commonly subhedral. On the basis of coal chemistry and grain morphology, we suggest that volcanic components in the tonstein were leached by ground water. The leachate, rich in Y and REE precipitated as authigenic mineral phases in the underlying coal.The Fire Clay coal bed in the Central Appalachian basin region contains a laterally-persistent tonstein that is found in the coal throughout most of its areal extent. The tonstein contains an array of minerals, including sanidine, ??-quartz, anatase and euhedral zircon, that constitutes strong evidence for a volcanic origin of the parting. For this study, five samples of the tonstein and four sets of coal samples underlying the tonstein were collected from five sites in eastern Kentucky. Inductively coupled plasma-mass spectroscopy (ICP-MS) analysis of the tonstein and underlying coal collected from four sites in eastern Kentucky show that although Zr concentrations are high in the tonstein (570-1820 ppm on a coal-ash basis (cab)), they are highest in the coal directly underlying the tonstein (2870-4540 ppm (cab)). A similar enrichment pattern is observed in the concentration of Y plus the sum of the rare earth elements (Y+???REE): total Y+???REE concentrations in the five tonstein samples range from 511 to 565 ppm (cab). However, Y+???REE contents are highest in the coals directly underlying the tonsteins: values range from 1965 to 4198 ppm (cab). Scanning electron microscopy of samples from coal which directly underlies two of the tonstein samples show that REE-rich phosphate, tentatively identified as monazite, commonly infills cracks in clays and cells in clarain and vitrain. Zircon is rare and commonly subhedral. On the basis of coal chemistry and grain morphology, we suggest that volcanic components in the tonstein were leached by ground water. The leachate, rich in Y and REE precipitated as authigenic mineral phases in the underlying coal.

Rare earth elements in pore waters from Cabo Friós western boundary upwelling system

NASA Astrophysics Data System (ADS)

Smoak, J. M.; Silva-Filho, E. V.; Rousseau, T.; Albuquerque, A. L.; Caldeira, P. P.; Moreira, M.

2015-12-01

Rare earth elements (REE) are a group of reactive trace elements in aqueous media, they have a coherent chemical behavior with however a subtle and gradual shift in physicochemical properties allowing their use as tracers of sources and processes. Uncertainties on their oceanic inputs and outputs still remains [Arsouze et al., 2009; Siddall et al., 2008; Tachikawa et al., 2003]. The water-sediment interface were early on identified as a relevant REE source due to the high distribution coefficient between sediments and pore waters [Elderfield and Sholkovitz, 1987] and substantially higher concentration then the water column [Abbott et al., 2015; Haley et al., 2004; Sholkovitz et al., 1989; Soyol-Erdene and Huh, 2013]. Here we present a cross shelf transect of 4 short pore waters REE profiles on a 680 km2 mud bank located in the region of Cabo Frio, Brazil. This study reveals similar trends at the four sites: a REE production zone reflected by a maximum in concentration at the top of the sediment evolving with depth toward a REE consumption zone reflected by a minimum in REE concentrations. PAAS normalized patterns shows 1) a progressive depletion in LREE with depth with HREE/LREE ratios comprised between 1.1 and 1.6 in the 2 first centimeters evolving gradually to ratios comprised between 2.8 and 4.7 above 7 cm 2) A sharp gradient in negative Ce anomaly with Ce/Ce* values reaching 0.3. With maximum Nd concentrations comprised between 780 and 1200 pmol.kg and considering that seawater Nd concentrations of Brazilian shelf bottom waters are comprised between 24 and 50 pmol.Kg-1 we apply the Fick´s First Law of diffusion and estimate that 340 +/- 90 nmol. m-2 Y-1 of Nd is released in the Cabo frio´s mudbank. This flux is in the same order of magnitude of recent estimates by [Abbott et al., 2015] in the slope of Oregon´s margin. Unraveling processes responsible for the REE production zone will help to refine the global REE fluxes estimates.

Direct determination of europium valence state by XANES in extraterrestrial merrillite: Implications for REE crystal chemistry and martian magmatism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shearer, C.K.; Papike, J.J.; Burger, P.V.

2012-03-15

The relative proportion of divalent and trivalent Eu has proven to be a useful tool for estimating f{sub O{sub 2}} in various magmatic systems. However, in most cases, direct determination of the Eu valence state has not been made. In this study, direct determination of Eu valence by XANES and REE abundance in merrillite provide insights into the crystal chemistry of these phosphates and their ability to record conditions of magmatism. Merrillite strongly prefers Eu{sup 3+} to Eu{sup 2+}, with the average valence state of Eu ranging between 2.9 and 3 over approximately six orders of magnitude in f{sub O{submore » 2}}. The dramatic shift in the REE patterns of merrillite in martian basaltic magmas, from highly LREE-depleted to LREE-enriched, parallels many other trace element and isotopic variations and reflects the sources for these magmas. The behavior of REE in the merrillite directly reflects the relationship between the eightfold-coordinated Ca1 site and adjacent sixfold Na and tetrahedral P sites that enables charge balancing through coupled substitutions.« less

Peering Through a Martian Veil: ALHA84001 Sm-Nd Age Revisited

NASA Technical Reports Server (NTRS)

Nyquist, Laurence E.; Shih, Chi-Yu

2013-01-01

The ancient Martian orthopyroxenite ALH84001experienced a complex history of impact and aqueous alteration events. Here we summarize Sm-147-Nd-143 and Sm-146-Nd-142 analyses performed at JSC. Further, using REE data, we model the REE abundance pattern of the basaltic magma parental to ALH84001 cumulus orthopyroxene. We find the Sm-146-Nd-142 isotopic data to be consistent with isotopic evolution in material having the modeled Sm/Nd ratio from a time very close to the planet's formation to igneous crystallization of ALH84001 as inferred from the Sm-Nd studies.

Stability constants for mono- and dioxalato-complexes of Y and the REE, potentially important species in groundwaters and surface freshwaters

NASA Astrophysics Data System (ADS)

Schijf, J.; Byrne, R. H.

2001-04-01

We present the first measured set of stability constants for mono- and dioxalato-complexes of yttrium and all rare earths except Pm (Y+REE), Oxβ n = [MOx n3-2n] [M 3+] -1 [Ox 2-] -n(where [ ] ≡ concentrations, M ≡ Y+REE, and Ox 2- ≡ C 2O 42-). Aqueous solutions of Y+REE were titrated with oxalic acid in the presence of a cation-exchange resin, and Y+REE concentrations in the solution phase were measured by ICP-MS. This method allows investigation of all Y+REE simultaneously under identical conditions and is thus very sensitive to subtle inter-element variations in log Oxβ n. Experiments were performed at a single ionic strength ( I = 0.05 M), but at two values of pH. Patterns of log Oxβ 1 and log Oxβ 2, determined from our experiments, are similar in shape and reminiscent of those for carbonato-complexes. The average ratio of stepwise stability constants K 2/K 1 = Oxβ 2/( Oxβ 1) 2 is 0.05 ± 0.02 for Y+REE excluding La and Ce. Literature values of Oxβ 1(Eu) for 0.03 mol/L ≤ I ≤ 1 mol/L were used to derive the relation log Oxβ 1(Eu) = log Oxβ 10(Eu) - 6.132√ I/(1 + 1.47√ I) + 0.902 I, where log Oxβ 10(Eu) is the stability constant at infinite dilution. Applying this relation to all Y+REE, the following values of log Oxβ 10 (at zero ionic strength) were found: 6.66 (Y), 5.87 (La), 5.97 (Ce), 6.25 (Pr), 6.31 (Nd), 6.43 (Sm), 6.52 (Eu), 6.53 (Gd), 6.63 (Tb), 6.74 (Dy), 6.77 (Ho), 6.83 (Er), 6.89 (Tm), 6.95 (Yb), 6.96 (Lu). These values, which are based on direct measurements for each individual Y+REE, agree quite well with published extrapolations that are mostly based on linear free-energy relationships. Total oxalate concentrations of 10 -5-10 -3 M have been reported for soil solutions. Free oxalate ions persist at much lower pH than free carbonate ions and a simple speciation model demonstrates that oxalato-complexes can dominate Y+REE speciation in mildly acidic groundwaters of low-to-moderate alkalinity.

A new method for the determination of Gadolinium in ppq levels

NASA Astrophysics Data System (ADS)

Brünjes, Robert; Bichler, Andrea; Hofmann, Thilo

2015-04-01

The use of Gadolinium (Gd) complexes as a contrast agent in Magnetic Resonance Imaging (MRI) results in an enhanced Gd input in the aquatic environment. Gd-complexes are excreted by humans unmetabolized within 12h after application. Passing the sewage systems with almost no degradation taking place, they successively reach surface waters, which make Gd a capable tracer for surface water/groundwater (SW/GW) interactions. The natural background concentration of Gd and other rare earth elements (REE) occur at ultratrace levels [low ng/L]. Crust-normalized REE patterns show positive Gd-anomalies in surface water, groundwater, and recently also in tap water. The difference between the total concentration and its natural background concentration estimated by the REE pattern is the anthropogenic Gd. Not only densely populated areas are affected by the presence of anthropogenic Gd. Studies have shown that even in rural areas without MRI facilities, anthropogenic Gd can be detected, since people are sent home after treatment. However, low input concentrations and mixing with natural waters lead to a decrease of Gd concentration below the current limit of quantification (LOQ) [1-5ng/L]. Often anthropogenic Gd cannot be calculated, although it is present, because natural background concentration cannot be determined with current methods, in particular in areas with low waste water load (e.g. headwater catchments). A new method using an on-line preconcentration system "SeaFAST" (Elemental Scientific Inc., USA), in combination with a desolvation system "Apex Q" (Elemental Scientific Inc., USA) and a QQQ-ICP-MS instrument (Agilent Technologies, Japan) does lower the LOQ for REE by a factor of 10 to 20. The SeaFAST-system uses a resin with ethylenediaminetriacetic acid and iminodiacetic acid functional groups to preconcentrate specifically REE as they are exclusively trivalent while anions, alkali and alkaline earth cations are washed out. The Apex Q interface is also supposed to significantly lower oxide interferences. We also evaluate a pretreatment in order to degrade the complexes and reach high recoveries of anthropogenic Gd. Our method will provide a determination of REE in ppq-levels, that significantly improves the differentiation between naturally and anthropogenic Gd. This will allow the detection of less than 1% waste water in SW and GW and finally increase the areas where studies of anthropogenic Gd could be conducted. A first application of our method was conducted during a field study in November 2014.

Fusion Bead Procedure for Nuclear Forensics Employing Synthetic Enstatite to Dissolve Uraniferous and Other Challenging Materials Prior to Laser Ablation Inductively Coupled Plasma Mass Spectrometry.

PubMed

Reading, David G; Croudace, Ian W; Warwick, Phillip E

2017-06-06

There is an increasing demand for rapid and effective analytical tools to support nuclear forensic investigations of seized or suspect materials. Some methods are simply adapted from other scientific disciplines and can effectively be used to rapidly prepare complex materials for subsequent analysis. A novel sample fusion method is developed, tested, and validated to produce homogeneous, flux-free glass beads of geochemical reference materials (GRMs), uranium ores, and uranium ore concentrates (UOC) prior to the analysis of 14 rare earth elements (REE) via laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The novelty of the procedure is the production of glass beads using 9 parts high purity synthetic enstatite (MgSiO 3 ) as the glass former with 1 part of sample (sample mass ∼1.5 mg). The beads are rapidly prepared (∼10 min overall time) by fusing the blended mixture on an iridium strip resistance heater in an argon-purged chamber. Many elements can be measured in the glass bead, but the rare earth group in particular is a valuable series in nuclear forensic studies and is well-determined using LA-ICP-MS. The REE data obtained from the GRMs, presented as chondrite normalized patterns, are in very good agreement with consensus patterns. The UOCs have comparable patterns to solution ICP-MS methods and published data. The attractions of the current development are its conservation of sample, speed of preparation, and suitability for microbeam analysis, all of which are favorable for nuclear forensics practitioners and geochemists requiring REE patterns from scarce or valuable samples.

Cerium anomaly at microscale in fossils.

PubMed

Gueriau, Pierre; Mocuta, Cristian; Bertrand, Loïc

2015-09-01

Patterns in rare earth element (REE) concentrations are essential instruments to assess geochemical processes in Earth and environmental sciences. Excursions in the "cerium anomaly" are widely used to inform on past redox conditions in sediments. This proxy resources to the specificity of cerium to adopt both the +III and +IV oxidation states, while most rare earths are purely trivalent and share very similar reactivity and transport properties. In practical terms, the level of cerium anomaly is established through elemental point quantification and profiling. All these models rely on a supposed homogeneity of the cerium oxidation state within the samples. However, this has never been demonstrated, whereas the cerium concentration can significantly vary within a sample, as shown for fossils, which would vastly complicate interpretation of REE patterns. Here, we report direct micrometric mapping of Ce speciation through synchrotron X-ray absorption spectroscopy and production of local rare earth patterns in paleontological fossil tissues through X-ray fluorescence mapping. The sensitivity of the approach is demonstrated on well-preserved fishes and crustaceans from the Late Cretaceous (ca. 95 million years (Myr) old). The presence of Ce under the +IV form within the fossil tissues is attributed to slightly oxidative local conditions of burial and agrees well with the limited negative cerium anomaly observed in REE patterns. The [Ce(IV)]/[Ce(tot)] ratio appears remarkably stable at the microscale within each fossil and is similar between fossils from the locality. Speciation maps were obtained from an original combination of synchrotron microbeam X-ray fluorescence, absorption spectroscopy, and diffraction, together with light and electron microscopy. This work also highlights the need for more systematic studies of cerium geochemistry at the microscale in paleontological contexts, in particular across fossil histologies.

Tracking the depleted mantle signature in melt inclusions and host glass of basaltic martian shergottites using secondary ionization mass spectrometry

NASA Astrophysics Data System (ADS)

Peters, T. J.; Simon, J. I.; Jones, J. H.; Usui, T.; Economos, R. C.; Schmitt, A. K.; McKeegan, K. D.

2013-12-01

Trace element abundances of depleted shergottite magmas recorded by olivine-hosted melt inclusions (MI) and interstitial mesostasis glass were measured using the CAMECA ims-1270 ion microprobe. Two meteorites: Tissint, an olivine-phyric basaltic shergottite which fell over Morocco July 18th 2001; and the Antarctic meteorite Yamato 980459 (Y98), an olivine-phyric basaltic shergottite with abundant glassy mesostasis have been studied. Chondrite-normalized REE patterns for MI in Tissint and Y98 are characteristically LREE depleted and, within analytical uncertainty, parallel those of their respective whole rock composition; supporting each meteorite to represent a melt composition that has experienced closed-system crystallization. REE profiles for mesostasis glass in Y98 lie about an order of magnitude higher than those from the MI; with REE profiles for Tissint MI falling in between. Y98 MI have the highest average Sm/Nd and Y/Ce ratios, reflecting their LREE depletion and further supporting Y98 as one of our best samples to probe the depleted shergotitte mantle. In general, Zr/Nb ratios overlap between Y98 and Tissint MI, Ce/Nb ratios overlap between Y98 MI and mesostasis glass, and Sm/Nd ratios overlap between Y98 mesostasis glass and Tissint MI. These features support similar sources for both, but with subtle geochemical differences that may reflect different melting conditions or fractionation paths during ascent from the mantle. Interestingly, the REE patterns for all analyses in Y98 and possibly for those from Tissint as well display a flattening of the LREE that suggests an early crustal contribution to the shergottite mantle.

Tracking the Depleted Mantle Signature in Melt Inclusions and Residual Glass of Basaltic Martian Shergottites using Secondary Ionization Mass Spectrometry

NASA Technical Reports Server (NTRS)

Peters, Timothy J.; Simon, Justin I.; Jones, John H.; Usui, Tomohiro; Economos, Rita C.; Schmitt, Axel K.; McKeegan, Kevin D.

2013-01-01

Trace element abundances of depleted shergottite magmas recorded by olivine-hosted melt inclusions (MI) and interstitial mesostasis glass were measured using the Cameca ims-1270 ion microprobe. Two meteorites: Tissint, an olivine-­phyric basaltic shergottite which fell over Morocco July 18th 2001; and the Antarctic meteorite Yamato 980459 (Y98), an olivine-phyric basaltic shergottite with abundant glassy mesostasis have been studied. Chondrite-­normalized REE patterns for MI in Tissint and Y98 are characteristically LREE depleted and, within analytical uncertainty, parallel those of their respective whole rock composition; supporting each meteorite to represent a melt composition that has experienced closed-­system crystallization. REE profiles for mesostasis glass in Y98 lie about an order of magnitude higher than those from the MI; with REE profiles for Tissint MI falling in between. Y98 MI have the highest average Sm/Nd and Y/Ce ratios, reflecting their LREE depletion and further supporting Y98 as one of our best samples to probe the depleted shergotitte mantle. In general, Zr/Nb ratios overlap between Y98 and Tissint MI, Ce/Nb ratios overlap between Y98 MI and mesostasis glass, and Sm/Nd ratios overlap between Y98 mesostasis glass and Tissint MI. These features support similar sources for both, but with subtle geochemical differences that may reflect different melting conditions or fractionation paths during ascent from the mantle. Interestingly, the REE patterns for both Y98 bulk and MI analyses display a flattening of the LREE that suggests a crustal contribution to the Y98 parent melt. This observation has important implications for the origins of depleted and enriched shergottites.

Data availability and the need for research to localize, quantify and recycle critical metals in information technology, telecommunication and consumer equipment.

PubMed

Chancerel, Perrine; Rotter, Vera Susanne; Ueberschaar, Maximilian; Marwede, Max; Nissen, Nils F; Lang, Klaus-Dieter

2013-10-01

The supply of critical metals like gallium, germanium, indium and rare earths elements (REE) is of technological, economic and strategic relevance in the manufacturing of electrical and electronic equipment (EEE). Recycling is one of the key strategies to secure the long-term supply of these metals. The dissipation of the metals related to the low concentrations in the products and to the configuration of the life cycle (short use time, insufficient collection, treatment focusing on the recovery of other materials) creates challenges to achieve efficient recycling. This article assesses the available data and sets priorities for further research aimed at developing solutions to improve the recycling of seven critical metals or metal families (antimony, cobalt, gallium, germanium, indium, REE and tantalum). Twenty-six metal applications were identified for those six metals and the REE family. The criteria used for the assessment are (i) the metal criticality related to strategic and economic issues; (ii) the share of the worldwide mine or refinery production going to EEE manufacturing; (iii) rough estimates of the concentration and the content of the metals in the products; (iv) the accuracy of the data already available; and (v) the occurrence of the application in specific WEEE groups. Eight applications were classified as relevant for further research, including the use of antimony as a flame retardant, gallium and germanium in integrated circuits, rare earths in phosphors and permanent magnets, cobalt in batteries, tantalum capacitors and indium as an indium-tin-oxide transparent conductive layer in flat displays.

Exercise Training and Energy Expenditure following Weight Loss

PubMed Central

Hunter, Gary R.; Fisher, Gordon; Neumeier, William H.; Carter, Stephen J.; Plaisance, Eric P.

2015-01-01

Purpose Determine the effects of aerobic or resistance training on activity related energy expenditure (AEE, kcal/d) and physical activity index (ARTE) following weight loss. It was hypothesized that weight loss without exercise training would be accompanied by a decrease in AEE, ARTE, and non-training physical activity energy expenditure (NEAT) and that exercise training would prevent decreases in free living energy expenditure. Methods 140 pre-menopausal women underwent an average of 25 pound weight loss during an 800 kcal/day diet of furnished food. One group aerobically trained 3 times/wk (40 min/d), another resistance trained 3 times/wk (10 exercises/2 sets x10 repetitions) and the third group did not exercise. DXA was used to measure body composition, indirect calorimetry to measure resting (REE) and walking energy expenditure, and doubly labeled water to measure total energy expenditure (TEE). AEE, ARTE, and non-training physical activity energy expenditure (NEAT) were calculated. Results TEE, REE, and NEAT all decreased following weight loss for the no exercise group, but not for the aerobic and resistance trainers. Only REE decreased in the two exercise groups. The resistance trainers increased ARTE. Heart rate and oxygen uptake while walking on the flat and up a grade were consistently related to TEE, AEE, NEAT, and ARTE. Conclusion Exercise training prevents a decrease in energy expenditure, including free living energy expenditure separate from the exercise training, following weight loss. Resistance training increased physical activity, while ease and economy in walking associates with increased TEE, AEE, NEAT, and ARTE. PMID:25606816

A survey of the selenochemistry of major, minor and trace elements.

NASA Technical Reports Server (NTRS)

Schmitt, R. A.; Laul, J. C.

1973-01-01

Average data for igneous and/or metaigneous rocks and soils from seven lunar sites are presented. There are compositional similarities between Apollo 11 and Luna 16 eastern maria, Ap 12 and 15 western maria, and between Ap 16 and L 20 highlands. Subtle differences do exist between the paired mare sites and the two highland sites and striking differences between the eastern and western maria. Chondritic normalized REE (rare earth element) patterns for igneous rocks and soils from all sites range from 7-350 generally with negative Eu anomalies. Anorthositic gabbroes to anorthosites, presumably highland material, exhibit a positive Eu anomaly. The REE patterns or Sr isotopic ratios suggest two lava flows each for the L 16 and Ap 14 sites, at least four lava flows for the Ap 11 and 12 site and about six for the Ap 15 site.

Geochemical Evidence for Recent Hydrothermal Alteration of Marine Sediments in Mid-Okinawa Trough, Southwest Japan

NASA Astrophysics Data System (ADS)

Tanaka, A.; Abe, G.; Yamaguchi, K. E.

2014-12-01

Recent studies have shown that submarine hydrothermal system supports diverse microbial life. Bio-essential metals supporting such microbial communities were released from basalts by high-temperature water-rock interaction in deeper part of the oceanic crust and carried by submarine fluid flow. Its total quantity in global hydrothermal settings has been estimated to be on the order of ~1019 g/yr, which is surprisingly on the same order of the total river flows (Urabe et al., 2011). Therefore, it is important to explore how submarine river system works, i.e., to understand mechanism and extent of elemental transport, which should lead to understanding of the roles of hydrothermal circulation in oceanic crust in controlling elemental budget in the global ocean and geochemical conditions to support deep hot biosphere. 　We performed REE analysis of marine sediments influenced by submarine hydrothermal activity in Mid-Okinawa Trough. The sediment samples used in this study are from IODP site at Iheya North region and JADE site at Izena region. The samples show alternation between volcanic and clastic sediments. Hydrothermal fluids of this area contain elevated concentrations of volatile components such as H2, CO2, CH4, NH4+, and H2S, supporting diverse chemoautotrophic microbial community (Nakagawa et al., 2005). The purpose of this study is to examine the effect of hydrothermal activity on the REE signature of the sediments. Chondrite-normalized REE patterns of the samples show relative enrichment of light over heavy REEs, weak positive Ce anomalies, and variable degrees of negative Eu anomalies. The REE patterns suggest the sediments source was mainly basalt, suggesting insignificant input of continental materials. Negative Eu anomalies found in the IODP site become more pronounced with increasing depth, suggesting progressive increase of hydrothermal alteration where Eu was reductively dissolved into fluids by decomposition of feldspars. Contrary, at the JADE site, magnitude of negative Eu anomalies was variable independent of the sediment depth. This suggests changes in the redox conditions, most likely due to occasional invasions of O2-bearing seawater into sediments. Different regimes of hydrothermal fluid flows govern the chemical environments of marine sediments in active hydrothermal areas.

Neodymium Isotope associated with planktonic foraminifera as a proxy of deglacial changes in Pacific ocean circulation

NASA Astrophysics Data System (ADS)

Hu, R.

2015-12-01

Neodymium isotopes of ferromanganese oxide coatings precipitated on planktonic foraminifera have been intensively used as a proxy for water mass reconstruction in the deep Atlantic and Indian Ocean, but their suitability is not well constrained in the Pacific and may be affected by enhanced inputs and scavenging relative to advection. In this study, Nd isotopes and Rare Earth Element (REE) concentrations of planktonic foraminifera from ~60 sites widely distributed throughout the Pacific are presented. We found that the REE pattern associated with planktonic foraminifera in our study and Fe-Mn oxides/coatings in the global ocean have a common heavy REE depleted pattern when normalized to their ambient seawater due to preferential removal of light REEs onto particles relative to heavy REEs during scavenging. The core-top ɛNd results agree with the proximal seawater compositions, indicating that planktonic foraminiferal coatings can give a reliable record of past changes in bottom water Nd isotopes in the Pacific. A good correlation between foraminifera Nd isotopes and seawater phosphate suggests that Nd with a predominantly radiogenic isotopic composition was probably added gradually along continental boundaries so that the Nd isotopic composition change paralleled the accumulation of nutrients in the deep Pacific. By confirming Nd isotopes as a reliable water mass tracer in the Pacific Ocean, this proxy is then applied to reconstruct how the water mass circulation changes during the Last Glacial Maximum (LGM). Most of the cores in deep North Pacific show essentially invariant Nd isotopic compositions during the LGM compared with core-top values, suggesting that Nd isotope of Pacific end-member did not change during glacial times. However, the LGM Southwest Pacific cores have more radiogenic ɛNd than core-tops corroborating the previous findings of reduced inflow of North Atlantic Deep Water. The Eastern Equatorial Pacific cores above ~2 km showed consistently lower LGM ɛNd values, which might suggest a reduced influence of more radiogenic North Pacific Deep Water return flow. Taken together, our results indicate a slower Pacific overturning circulation during the glacial times, and the inflow and return flow of the Pacific meridional overturning were closely linked in the glacial-interglacial cycles.

Application of unsupervised pattern recognition approaches for exploration of rare earth elements in Se-Chahun iron ore, central Iran

NASA Astrophysics Data System (ADS)

Sarparandeh, Mohammadali; Hezarkhani, Ardeshir

2017-12-01

The use of efficient methods for data processing has always been of interest to researchers in the field of earth sciences. Pattern recognition techniques are appropriate methods for high-dimensional data such as geochemical data. Evaluation of the geochemical distribution of rare earth elements (REEs) requires the use of such methods. In particular, the multivariate nature of REE data makes them a good target for numerical analysis. The main subject of this paper is application of unsupervised pattern recognition approaches in evaluating geochemical distribution of REEs in the Kiruna type magnetite-apatite deposit of Se-Chahun. For this purpose, 42 bulk lithology samples were collected from the Se-Chahun iron ore deposit. In this study, 14 rare earth elements were measured with inductively coupled plasma mass spectrometry (ICP-MS). Pattern recognition makes it possible to evaluate the relations between the samples based on all these 14 features, simultaneously. In addition to providing easy solutions, discovery of the hidden information and relations of data samples is the advantage of these methods. Therefore, four clustering methods (unsupervised pattern recognition) - including a modified basic sequential algorithmic scheme (MBSAS), hierarchical (agglomerative) clustering, k-means clustering and self-organizing map (SOM) - were applied and results were evaluated using the silhouette criterion. Samples were clustered in four types. Finally, the results of this study were validated with geological facts and analysis results from, for example, scanning electron microscopy (SEM), X-ray diffraction (XRD), ICP-MS and optical mineralogy. The results of the k-means clustering and SOM methods have the best matches with reality, with experimental studies of samples and with field surveys. Since only the rare earth elements are used in this division, a good agreement of the results with lithology is considerable. It is concluded that the combination of the proposed methods and geological studies leads to finding some hidden information, and this approach has the best results compared to using only one of them.

Partial melting under conditions of filter pressing: field and geochemical evidence from the migmatites of NE Minnesota

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheehan, T.J.; Bauer, R.L.; Nabelek, P.I.

1985-01-01

Amphibolite-grade Archean migmatites in the southern Vermilion Granitic Complex with well-defined paleosome-melanosome and melanosome-leucosome boundaries and with exceptionally wide melanosomes (on the order of centimeters) were studied to elucidate granite-forming processes during high-grade metamorphism. Metagreywacke paleosomes containing 50% plag, 28% qtz, 20% biot and minor hbld, and apat, have (Ce/Yb)/sub N/ = 13.5 to 21 with 650-960 ppm Ba, 42-110 ppm Rb, and 982-1159 ppm Sr. Melanosomes containing 45% plag, 35% biot, 20% hbld and minor qtz and apat, have (Ce/Yb)/sub N/ = 6.8 to 9.3 and have 950-1750 ppm Ba, 41-194 ppm Rb, and 1020-1926 ppm Sr. Leucosomes containingmore » 82% plag, 13% qtz, 5% biot and minor hbld and apat, have overall depleted REE patterns with positive Eu anomalies and 460-750 ppm Ba, 41-43 ppm Rb, and 1876-2106 ppm Sr, suggesting cumulate plagioclase. Mass balance calculations preclude formation of the melanosome from mixing the paleosomes and leucosomes. However, major and trace element modeling suggest that the leucosome formed by in situ partial melting followed by fractional crystallization and filter pressing which resulted in the removal of the residual liquid. Model REE patterns for the melt drive off by this process are REE enriched with a negative Eu anomaly. Such patterns which have been found in some low Sr granites are difficult to produce by simple belting models. Partial melting under conditions of tectonic stress may thus provide an explanation for such granites.« less

Whisker Formation on SAC305 Soldered Assemblies

NASA Astrophysics Data System (ADS)

Meschter, S.; Snugovsky, P.; Bagheri, Z.; Kosiba, E.; Romansky, M.; Kennedy, J.; Snugovsky, L.; Perovic, D.

2014-11-01

This article describes the results of a whisker formation study on SAC305 assemblies, evaluating the effects of lead-frame materials and cleanliness in different environments: low-stress simulated power cycling (50-85°C thermal cycling), thermal shock (-55°C to 85°C), and high temperature/high humidity (85°C/85% RH). Cleaned and contaminated small outline transistors, large leaded quad flat packs (QFP), plastic leaded chip carrier packages, and solder balls with and without rare earth elements (REE) were soldered to custom designed test boards with Sn3Ag0.5Cu (SAC305) solder. After assembly, all the boards were cleaned, and half of them were recontaminated (1.56 µg/cm2 Cl-). Whisker length, diameter, and density were measured. Detailed metallurgical analysis on components before assembly and on solder joints before and after testing was performed. It was found that whiskers grow from solder joint fillets, where the thickness is less than 25 µm, unless REE was present. The influence of lead-frame and solder ball material, microstructure, cleanliness, and environment on whisker characteristics is discussed. This article provides detailed metallurgical observations and select whisker length data obtained during this multiyear testing program.

Use of arsenic and REE in black shales as potential environmental tracers in hydraulic fracturing operations

NASA Astrophysics Data System (ADS)

Yang, J.; Torres, M. E.; Haley, B. A.; McKay, J. L.; Algeo, T. J.; Hakala, A.; Joseph, C.; Edenborn, H. M.

2013-12-01

Black shales commonly targeted for shale gas development were deposited under low oxygen concentrations, and typically contain high As levels. The depositional environment governs its solid-phase association in the sediment, which in turn will influence degree of remobilization during hydraulic fracturing. Organic carbon (OC), trace element (TE) and REE distributions have been used as tracers for assessing deep water redox conditions at the time of deposition in the Midcontinent Sea of North America (Algeo and Heckel, 2008), during large-scale oceanic anoxic events (e.g., Bunte, 2009) and in modern OC-rich sediments underlying coastal upwelling areas (e.g., Brumsack, 2006). We will present REE and As data from a collection of six different locations in the continental US (Kansas, Iowa, Oklahoma, Kentucky, North Dakota and Pennsylvania), ranging in age from Devonian to Upper Pennsylvanian, and from a Cretaceous black shale drilled on the Demerara Rise during ODP Leg 207. We interpret our data in light of the depositional framework previously developed for these locations based on OC and TE patterns, to document the mechanisms leading to REE and As accumulation, and explore their potential use as environmental proxies and their diagenetic remobilization during burial, as part of our future goal to develop a predictive evaluation of arsenic release from shales and transport with flowback waters. Total REE abundance (ΣREE) ranged from 35 to 420 ppm in an organic rich sample from Stark shale, KS. PAAS-normalized REE concentrations ranged from 0.5 to 7, with the highest enrichments observed in the MREE (Sm to Ho). Neither the ΣREE nor the MREE enrichments correlated with OC concentrations or postulated depositional redox conditions, suggesting a principal association with aluminosilicates and selective REE fractionation during diagenesis. In the anoxic reducing environments in which black shales were deposited, sulfide minerals such as FeS2 trap aqueous arsenic in the crystal lattice, but As is also known to bind to the charged surfaces of clay minerals. Our arsenic concentration data show that the highest abundances (up to 70 ppm) are found in sediments with the highest total sulfur concentration (to 2.6 ppm), but there was no clear correlation with organic carbon or aluminosilicate content. We compare our results with preliminary data from a series of flowback waters sampled from ten producing wells in Pennsylvania and from high-pressure high-temperature experimental leaching of Marcellus shale samples.

Occurrence of Two Different Types of Paleoarchean TTGs in Singhbhum craton, Eastern India: Insight from Geochemistry and Zircon Saturation Thermometry

NASA Astrophysics Data System (ADS)

Mitra, A.; Dey, S.

2017-12-01

Paleoarchean era is marked as an active period of continental crust genesis. A large part of the paleoarchean crust is made up of grey sodic granitoids collectively referred as Tonalite Trondjhemite Granodiorite (TTG). Generation and evolution of TTGs are still highly debated, though researchers agree on their generation through partial melting of hydrated basalt at garnet or amphibole stability field. Discrete remnants of paleoarchean TTGs are exposed in several parts of the Singhbhum craton, eastern India. Our study exhibits occurrence of two different types of TTGs based on REE pattern in a chondrite normalized REE diagram. Accordingly, TTGs have been grouped into two different types, namely (1) High HREE TTG [low SiO2; high HREE avg. (Gd/Er)n=2.23; less fractionated REE avg. (La/Yb)n=27.9 and relatively low Sr/Y avg. Sr/Y=53.59] and Low HREE TTG [high SiO2; depleted HREE avg. (Gd/Er)n=3.23; steeply fractionated REE avg. (La/Yb)n=46.11 and relatively high Sr/Y avg. Sr/Y= 95.49]. The two types of TTGs mainly differ in pressure sensitive signatures like Sr/Y and (La/Yb)n ratio. Considering the major element composition both the types are consistent with a low-K mafic source. This indicates, melting occurred at different crustal levels from a same/similar source. Moderate Al2O3, high Sr contents coupled with depleted HREE and Y are linked to the presence of garnet in either residual or fractionating phase. However, HREE variation is controlled by the amount of Garnet retained in the restite. Thus, in spite of melting of the source rock in garnet stability field, only the minor change in depth of melting and in turn different amount of retention of garnet in the source caused the difference in HREE pattern. Zircon saturation temperature (TZr) calculated on the basis of whole rock Zr concentration ranges from 735˚C to 760 ˚C (avg. 749˚C) for high HREE TTG and 750 ˚C to 802˚C (avg. 773˚C) for low HREE TTG. Absence of zircon xenocryst depicts zircon undersaturated melt, thus calculated TZr provides minimum estimate of the real magma temperature. High temperature magmas (Low HREE) formed at deeper level retained more garnet in source compare to low temperature magma (High HREE). Hence, temperature difference in TTG magmas is consistent with differences in REE pattern and grouping of TTGs, considering a normal geothermal gradient.

Rare Earth Element Concentrations and Fractionation Patterns Along Groundwater Flow Paths in Two Different Aquifer Types (i.e., Sand vs. Carbonate)

NASA Astrophysics Data System (ADS)

Johannesson, K. H.; Tang, J.

2003-12-01

Groundwater samples were collected in two different types of aquifer (i.e., Carrizo Sand Aquifer, Texas and Upper Floridan carbonate Aquifer, west-central Florida) to study the concentrations, fractionation, and speciation of rare earth elements (REE) along groundwater flow paths in each aquifer. Major solutes and dissolved organic carbon (DOC) were also measured in these groundwaters. The Carrizo Sand aquifer was sampled in October 2002 and June 2003, whereas, to date, we have only sampled the Floridan once (i.e., June 2003). The data reveal no significant seasonal differences in major solute and REE concentrations for the Carrizo. In Carrizo sand aquifer, groundwaters from relatively shallow wells (i.e., less than 167 m) in the recharge zone are chiefly Ca-Na-HCO3-Cl type waters. With flow down-gradient the groundwaters shift composition to the Na-HCO3 waters. pH and alkalinity initially decrease with flow away from the recharge zone before increasing again down-gradient. DOC is generally low (0.65 mg/L) along the flow path. REE concentrations are highest in groundwaters from the recharge zone (Nd 40.5 pmol/kg), and decrease substantially with flow down-gradient reaching relatively low and stable values (Nd 4.1-8.6 pmol/kg) roughly 10 km from the recharge zone. Generally, Carrizo groundwaters exhibit HREE-enriched shale-normalized patterns. The HREE enrichments are especially strong for waters from the recharge zone [(Yb/Nd)SN =1.7-5.6], whereas down-gradient (deep) groundwaters have flatter patterns [(Yb/Nd)SN =0.7-2.5]. All groundwaters have slightly positive Eu anomalies (Eu/Eu* 0.09-0.14) and negative Ce anomalies (Ce/Ce* -0.85 - -0.07). In the Upper Floridan Aquifer, Ca, Mg, SO4, and Cl concentrations generally increase along groundwater flow path, whereas pH and alkalinity generally decrease. DOC is higher (0.64 - 2.29 mg/L) than in the Carrizo and initially increases along the flow path and then decreases down-gradient. LREE (Nd) concentrations generally increase along groundwater flow path, however, MREE (Gd) exhibit little change and HREE (Yb) concentrations tend to decreases along the flow path. Floridan groundwaters have HREE enriched shale-normalized patterns, although (Yb/Nd)SN values decrease along groundwater flow path. Thus, REE patterns of Floridan groundwaters tend to flatten with flow down-gradient. All groundwaters show positive Eu anomalies (0.06 - 0.17) and negative Ce anomalies (-0.12 - -0.63).

Geochemistry of the Upper Triassic black mudstones in the Qiangtang Basin, Tibet: Implications for paleoenvironment, provenance, and tectonic setting

NASA Astrophysics Data System (ADS)

Wang, Zhongwei; Wang, Jian; Fu, Xiugen; Zhan, Wangzhong; Armstrong-Altrin, John S.; Yu, Fei; Feng, Xinglei; Song, Chunyan; Zeng, Shengqiang

2018-07-01

The Qiangtang Basin is the largest Mesozoic marine basin in the Tibetan Plateau. The Upper Triassic black mudstones are among the most significant hydrocarbon source rocks in this basin. Here, we present geochemical data for the Upper Triassic black mudstones to determine their paleoenvironment conditions, provenance, and tectonic setting. To achieve these, 30 black mudstones formed in various sedimentary environments were collected from the Zangxiahe, Zana, and Bagong formations. The results show that the total REE concentrations of mudstones from these formations range from 169 to 214 ppm, 204 to 220 ppm, and 141 to 194 ppm, respectively. All samples have chondrite-normalized REE patterns with enrichment of LREE, depletion of HREE and negative Eu and Ce anomalies. Specifically, mudstones from the Bagong Formation exhibit higher negative Eu anomalies and lower REE contents than those from the Zangxiahe and Zana formations. Mudstones from the Zangxiahe and Zana formations with low Sr/Ba and Sr/Cu ratios indicate the humid climate, whereas the high Sr/Ba and Sr/Cu ratios of rocks from the Bagong Formation suggest the arid climate. The low U/Th, (Cu + Mo)/Zn, V/Cr and Ni/Co ratios of rocks from the Zangxiahe, Zana, and Bagong formations are indicators of oxidized conditions. The bivariate diagrams (TiO2 vs. Al2O3, TiO2 vs. Zr, La/Th vs. Hf, and Co/Th vs. La/Sc) reveal that mudstones from the Zangxiahe and Zana formations were potentially derived from intermediate igneous rocks, whereas mudstones from the Bagong Formation were probably sourced from felsic igneous rocks. Their source rocks are mostly deposited in the collisional setting. REE of mudstones from the Zangxiahe, Zana, and Bagong formations were possibly originated from terrigenous detritus, with minor non-terrigenous contributions into the Zana samples. The REE contents of these mudstones are controlled mainly by terrigenous detrital minerals, rather than by the paleoclimate, paleoredox conditions, or organic matter. However, calcite minerals could dilute REE. Therefore, the REE contents of the Bagong Formation mudstones are significant lower than those of the Zangxiahe and Zana formations mudstones.

Dissolved Rare Earth Elements in the US GEOTRACES North Atlantic Section

NASA Astrophysics Data System (ADS)

Shiller, A. M.

2016-12-01

The rare earth elements (REEs) are a unique chemical set wherein there are systematic changes in geochemical behavior across the series. Furthermore, while most REEs are in the +III oxidation state, Ce and Eu can be in other oxidation states leading to distinct characteristics of those elements. Thus, the geochemical properties of the REEs make them particularly useful tools for inquiring into various geochemical processes. As part of the US GEOTRACES effort, we determined dissolved REEs and Y at 32 stations across the North Atlantic during US cruises GT10 and GT11 along a meridional transect from Lisbon to the Cape Verde Islands and a zonal transect from Cape Cod to the Mauritanian coast. While profiles are similar to previous reports, the high spatial resolution of the section allows for better elucidation of processes. Light rare earths (LREEs) show removal in the upper water column with a minimum at the chlorophyll maximum. LREE concentrations then increase into the oxygen minimum followed by a slight decrease and fairly constant concentrations in the mid-water column followed by an increase into the deep and bottom waters. Heavy rare earths (HREEs) show a more monotonic increase with depth. We also take advantage of a previously published water mass analysis for the section to estimate that most of the deep water changes can be explained by conservative mixing of waters with different pre-formed REE concentrations. Nonetheless, the pattern of LREE shallow water removal followed by regeneration, possible re-scavenging, and then deep water input is still preserved. Other features of note include an increase in LREEs in the strong oxygen minimum zone off Mauritania, consistent with an association of REE cycling with the redox cycles of Fe and Mn. Also along the eastern margin, but below the oxygen minimum, a small but distinct increase in the cerium and europium anomalies is observed, consistent with terrigenous input. In hydrothermally influenced waters along the mid-Atlantic Ridge, there are increases in Ce/Ce*, Eu/Eu*, and Y/Ho but a decrease in Nd/Yb and in REE concentrations. Surface water distributions are more consistent with elements influenced by margin inputs than with atmospheric input.

Submarine groundwater discharge of rare earth elements: Evidence of an important trace element flux to coastal waters

NASA Astrophysics Data System (ADS)

Johannesson, K. H.; Chevis, D.; Burdige, D. J.; Cable, J. E.; Martin, J. B.; Roy, M.

2008-12-01

Johannesson and Burdige [2007, EPSL 253, 129] suggested that submarine groundwater discharge (SGD) represents a substantial, unrecognized source of Nd to the oceans. Based on a globally averaged terrestrial SGD flux equal to 6 percent of the global river discharge and mean groundwater Nd concentrations obtained from the literature, we estimated a global SGD Nd flux that was within a factor of 2 of the previously proposed missing global Nd flux. To test our hypothesis that SGD is an important source of Nd to the oceans, rare earth element (REE) concentrations were measured in SGD samples collected beneath a coastal lagoon on the Florida Atlantic coast (Indian River Lagoon). Shale (PAAS)-normalized REE patterns for all SGD samples exhibit substantial enrichments in the heavy REEs (HREE) compared to the light REEs (LREE) as shown by their PAAS-normalized Yb/Nd ratios, which range from 5 to 73 (mean = 16). SGD from piezometers located 10 m and 22.5 m from shore exhibit PAAS-normalized REE plots that are most similar to the patterns of the overlying lagoon (surface) water. For example, mean PAAS-normalized Yb/Nd ratios for groundwaters sampled from the 10 m and 22.5 m piezometers are 6.7 and 8.3, which compare well with the PAAS- normalized Yb/Nd ratio of water column samples (8.7). In contrast, the mean PAAS-normalized Yb/Nd ratio of terrestrial-derived groundwater from the piezometer at the shoreline is 41. Neodymium concentrations of the SGD samples range from 230 to 2400 pmol/kg (mean = 507 pmol/kg), and thus are substantially higher than reported for open ocean seawater (typical Nd = 20 pmol/kg). Based on SGD fluxes previously determined with seepage meters, porewater Cl concentrations, and Rn-222 deficiencies of porewaters [Martin et al., 2007, Water Resour. Res. 43, W0544, doi: 10.1029/2006WR005266], we estimate daily inputs of Nd to the Indian River Lagoon of 50 to 2100 umoles for the terrestrial-derived component of SGD, and 171 mmoles for the marine component of SGD (81 to 3400 times greater). Residence times of Nd in the portion of the lagoon studied are estimated to range from 6 to more than 250 years based on the terrestrial-derived SGD flux of Nd, compared to 26 days using the marine-derived SGD flux of Nd. The substantially shorter residence time determined using the marine-derived SGD component compares well with the estimated flushing time for this portion of the estuary (~3 weeks). The similarity between SGD and lagoon water Nd concentrations and PAAS-normalized REE patterns, in conjunction with the larger, marine-derived SGD flux of Nd, strongly suggests that recirculation of lagoon water and subsequent SGD exerts the principal control on Nd concentrations in the lagoon. The elevated Nd concentration for deep groundwater (186 cmbsf) located 22.5 m from shore also agrees well with another study that reported recirculated, marine SGD as a source of REEs to coastal waters [Duncan and Shaw, 2003, Aquatic Geochem. 9, 233]. Thus, our observations demonstrate the importance of recirculated, marine SGD to these lagoon surface waters, and further support our hypothesis that SGD contributes substantial fluxes of Nd to the coastal oceans.

Accumulation and fractionation of rare earth elements (REEs) in the naturally grown Phytolacca americana L. in southern China.

PubMed

Yuan, Ming; Liu, Chang; Liu, Wen-Shen; Guo, Mei-Na; Morel, Jean Louis; Huot, Hermine; Yu, Hong-Jie; Tang, Ye-Tao; Qiu, Rong-Liang

2018-04-16

The widespread use of rare earth elements (REEs) has resulted in problems for soil and human health. Phytolacca americana L. is a herbaceous plant widely distributed in Dingnan county of Jiangxi province, China, which is a REE mining region (ion absorption rare earth mine) and the soil has high levels of REEs. An investigation of REE content of P. americana growing naturally in Dingnan county was conducted. REE concentrations in the roots, stems, and leaves of P. americana and in their rhizospheric soils were determined. Results showed that plant REEs concentrations varied among the sampling sites and can reach 1040 mg/kg in the leaves. Plant REEs concentrations decreased in the order of leaf > root > stem and all tissues were characterized by a light REE enrichment and a heavy REE depletion. However, P. americana exhibited preferential accumulation of light REEs during the absorption process (from soil to root) and preferential accumulation of heavy REEs during the translocation process (from stem to leaf). The ability of P. americana to accumulate high REEs in the shoot makes it a potential candidate for understanding the absorption mechanisms of REEs and for the phytoremediation of REEs contaminated soil.

The southwestern extension of the Jiao-Liao-Ji belt in the North China Craton: Geochronological and geochemical evidence from the Wuhe Group in the Bengbu area

NASA Astrophysics Data System (ADS)

Liu, Chaohui; Zhao, Guochun; Liu, Fulai; Cai, Jia

2018-04-01

The Wuhe complex is located at the southeastern margin of the North China Craton. The complex consists of metamorphosed Paleoproterozoic potassic granitoids and supracrustal rocks, of which the latter include the Fengyang and Wuhe groups. Meta-mafic rocks from the lower Wuhe Group have igneous zircon U-Pb ages of 2126 ± 37 Ma with εHf(t) values of -6.22 to +8.38, and xenocrystic zircons of 2.39-2.36 Ga, 2.55-2.54 Ga and 2.77-2.69 Ga. Geochemically, the meta-mafic rocks can be classified into two groups. Group 1 island arc tholeiites display flat to slightly right declined REE patterns and moderately negative Nb, Ta, Zr, and Ti anomalies. Group 2 mature arc calcalkaline basalts display strongly fractionated chondrite-normalized REE patterns and evidently negative Nb, Ta and Ti anomalies. These meta-mafic rocks formed by partial melting of sub-arc depleted mantle wedge which had been modified by slab-derived melts at an active continental margin. Depositional age of the group can be constrained in the period of 2.16-2.10 Ga based on ages of the youngest detrital zircons and latter intrusions. U-Pb ages of detrital zircons yield major age peaks of 2.69 Ga and 2.52 Ga, with minor peaks at 2.88 Ga, 2.78 Ga, 2.35 Ga and 2.17 Ga, most of which are derived from the late Mesoarchean to early Paleoproterozoic granitoids in the Wuhe complex and the Jiaodong Terrane. Metamorphic zircons in the marbles coexisting with garnet amphibolites or granulites occur as either single grains or overgrowth (or recrystallization) rims surrounding magmatic zircon cores and yield ages of 1882 ± 19 Ma to 1844 ± 15 Ma. The comparable ca. 2.1 Ga potassic granites with A-type granite affinity, the ca. 2.1 Ga meta-mafic rocks with arc-like geochemical features, the 2.1-1.9 Ga meta-sedimentary units and the 1.9-1.8 Ga subduction- and collision-related granulite-facies metamorphism suggest that the Wuhe complex and the Jiao-Liao-Ji Belt share the same late Paleoproterozoic tectonic evolution process and the former is the southwestern extension of the latter.

Factor Structure of the Air Force Officer Qualifying Test Form S: Analysis and Comparison with Previous Forms

DTIC Science & Technology

2008-10-01

training grades, and class rank (Carretta, in press; Carretta & Ree, 2003; Olea & Ree, 1994), and several non-aviation officer jobs (Arth, 1986...series of papers, Ree and colleagues ( Olea & Ree, 1994; Ree, Carretta, & Teachout, 1996; Ree, & Earles, 1991; Ree, Earles, & Teachout, 1994) showed...Report No. 4. Washington, DC: U.S. Government Printing Office. Olea , M. M., Ree, M. J. (1994). Predicting pilot and navigator criteria: Not much

Exercise Training and Energy Expenditure following Weight Loss.

PubMed

Hunter, Gary R; Fisher, Gordon; Neumeier, William H; Carter, Stephen J; Plaisance, Eric P

2015-09-01

This study aims to determine the effects of aerobic or resistance training on activity-related energy expenditure (AEE; kcal·d(-1)) and physical activity index (activity-related time equivalent (ARTE)) following weight loss. It was hypothesized that weight loss without exercise training would be accompanied by decreases in AEE, ARTE, and nontraining physical activity energy expenditure (nonexercise activity thermogenesis (NEAT)) and that exercise training would prevent decreases in free-living energy expenditure. One hundred forty premenopausal women had an average weight loss of 25 lb during a diet (800 kcal·d(-1)) of furnished food. One group aerobically trained 3 times per week (40 min·d(-1)), another group resistance-trained 3 times per week (10 exercises/2 sets × 10 repetitions), and the third group did not exercise. Dual-energy x-ray absorptiometry was used to measure body composition, indirect calorimetry was used to measure resting energy expenditure (REE) and walking energy expenditure, and doubly labeled water was used to measure total energy expenditure (TEE). AEE, ARTE, and nontraining physical activity energy expenditure (NEAT) were calculated. TEE, REE, and NEAT all decreased following weight loss for the no-exercise group, but not for aerobic and resistance trainers. Only REE decreased in the two exercise groups. Resistance trainers increased ARTE. HR and oxygen uptake while walking on the flat and up a grade were consistently related to TEE, AEE, NEAT, and ARTE. Exercise training prevents a decrease in energy expenditure, including free-living energy expenditure separate from exercise training, following weight loss. Resistance training increases physical activity, whereas economy/ease of walking is associated with increased TEE, AEE, NEAT, and ARTE.

The nature and history of the Qilian Block in the context of the development of the Greater Tibetan Plateau

NASA Astrophysics Data System (ADS)

Huang, Hui; Niu, Yaoling; Nowell, Geoff; Zhao, Zhidan; Yu, Xuehui; Mo, Xuanxue

2013-04-01

The Greater Tibetan Plateau is a geological amalgamation formed by several continental collision events from northeast in the Early Palaeozoic towards southwest in the Cenozoic. Compared to the youngest India-Asia collision event (~ 55 Ma), the earlier events to the north are not well understood, especially the earliest Qilian-Qaidam system at the northern margin. Understanding the petrogenesis of the Paleozoic granitoids in the Qilian Block (QB) helps understand the nature and history of the block, while also offering new perspectives on its sutures to the north (the North Qilian Orogenic Belt) and to the South (the North Qaidam Ultra-High Pressure Metamorphic Belt). Granitoids in the QB were sampled from several intrusions in two areas: Huangyuan (HY) and Gangcha (GC). All the samples are calc-alkaline varying from mafic-diorite to granite. Most of the HY samples are peraluminous containing Al-rich phases. The GC samples can be divided into two groups (fine-grained group with amphibole and coarse-grained without amphibole). Most HY samples are enriched in LREEs with flat HREE patterns (Group A). A garnet-bearing HY sample has elevated HREEs. Another three adakitic samples are depleted in HREEs with negative ?Hf(t) (-12~-11), indicating a deep crustal origin. The coarse-grained GC samples have similar REE patterns to HY group A while fine-grained samples have flat REE patterns with a stronger negative Eu anomaly. Zircons in all these samples are of magmatic origin but age data scatter along the Concordia and do not give "well-constrained" crystallization ages within a single sample. We adopt the histogram and identify the crystallization age with a peak at ~450 Ma. The ages of inherited zircons range from ~ 500 Ma to ~ 2600 Ma. The more peraluminous samples tend to have older inherited zircons, pointing to the greater old crust contribution. The older Proterozoic and Archean ages recorded in inherited zircons reveal the complex histories of the QB, which is likely a micro-continent or fragment of an ancient continent probably drifted from the Yangtze Craton. The initial whole-rock Sr-Nd-Pb-Hf isotopes of these samples vary significantly, e.g., ?Hf(t) (-15~+3), ?Nd(t)(-14.6~+2.6), radiogenic Pbi(206Pb/204Pbi: 18.20~20.63) and ISr (0.7051~0.7606). ?Hf(t) is negatively correlate with A/CNK indicating more peraluminous samples have more crustal contributions. Taken all the data together, we conclude that these granitoids are genetically associated with continental collision with varying amount of mantle input and contributions of heterogeneous basement rocks of the QB. Furthermore, the significantly correlated ?Hf(t) - ?Nd(t) variation is consistent with these granitoids being formed as the result of melting-induced mixing process. The crustal melting is most likely accomplished through heating by mantle derived basaltic melts, which in this context may be associated with seafloor subduction. Varying extents of melting of the crustal rocks with varying age/isotopic composition will give the observed compositional variability of the granitoids and the ?Hf(t) - ?Nd(t) correlation also reflects the mantle melt contributions as well as the different crustal lithologies of varying histories. As discussed above, the QB has the affinity of the Yangtze Craton and underwent ~450 Ma magmatism in a subduction/collision environment.

Slab and Sediment Melting during Subduction Initiation: Mantle Plagiogranites from the Oman Ophiolite

NASA Astrophysics Data System (ADS)

Rollinson, H. R.

2014-12-01

Granitoid dykes up to several hundred metres wide and 2 km long are found in depleted harzburgites in the mantle section of the Oman ophiolite. They vary in composition from tonalite to potassic granite and are generally more potassic than the crustal plagiogranites found within the sheeted dyke complex higher up within the ophiolite stratigraphy. Some granites are strongly peraluminous and contain garnet and andalusite. They are geochemically variable, some with REE that are relatively unfractionated ((La/Yb)n= 3.5-6.0, flat middle to heavy REE, steep light REE) to those which are highly fractionated ((La/Yb)n= 28-220). On primitive-mantle normalised plots some have very high concentrations of fluid-mobile elements - Cs, Rb, Th, U and Pb. Few have significant Ta-Nb anomalies. On the Ca-Fe-Mg-Ti discrimination diagram of Patino Douce (J. Petrol., 1999) whole-rock compositions define a spectrum between felsic-pelite derived melts and amphibolite-derived melts. There is a chemical similarity between the least REE fractionated plagiogranites (generally tonalites and granodiorites) and melts of an amphibolitic parent. This is supported by the occurrence of mafic xenoliths in some dykes, the presence of hornblende and highly calcic cores (up to An85) in some plagioclase grains. Trace element modelling using Oman Geotimes lavas as the starting composition indicates that melting took place in the garnet stability field, although enrichment in the melt in Cs, Rb, Ba and Pb suggests that there was another component present in addition to the mafic parent. Other plagiogranites (trondhjemites and granites) have a strongly peraluminous chemistry and mineralogy and geochemical similarities with the Himalayan leucogranites implying that they were derived from a sedimentary protolith. These mantle plagiogranites are more prevalent in the northern outcrops of the ophiolite. The volume of granitoid melt and the depth of melting preclude their derivation from the sole of the ophiolite, rather they were derived during subduction by the partial melting of the slab and associated sediment and emplaced into the overlying mantle wedge. Current subduction-initiation models for supra-subduction ophiolites should integrate this process into their thinking.

High-Mg subduction-related Tertiary basalts in Sardinia, Italy

NASA Astrophysics Data System (ADS)

Morra, V.; Secchi, F. A. G.; Melluso, L.; Franciosi, L.

1997-03-01

The Oligo-Miocene volcanics (32-15 Ma), which occur in the Oligo-Miocene Sardinian Rift, were interpreted in the literature as an intracontinental volcanic arc built upon continental crust about 30 km thick. They are characterized by a close field association of dominantly andesites and acid ignimbrites, with subordinate basalts. In this paper we deal with the origin and evolution of recently discovered high-magnesia basalts aged ca. 18 Ma occurring in the Montresta area, northern Sardinia, relevant to the petrogenesis of the Cenozoic volcanics of Sardinia. The igneous rocks of the Montresta area form a tholeiitic, subduction-related suite. Major-element variation from the high-magnesia basalts (HMB) to high-alumina basalts (HAB) are consistent with crystal/liquid fractionation dominated by olivine and clinopyroxene. Proportions of plagioclase and titanomagnetite increase from HAB to andesites. Initial {87Sr }/{86Sr } ratios increase with differentiation from 0.70398 for the HMB to 0.70592 for the andesites. This suggests concomitant crustal contamination. The geochemical characteristics of the high-magnesia basalts are typical of subduction-related magmas, with negative Nb, Zr and Ti spikes in mantle-normalized diagrams. It is proposed that these high-magnesia basalts were produced by partial melting of a mantle source characterized by large-ion lithophile elements (LILE) enrichment related principally to dehydration of subducted oceanic crust. Chondrite-normalized rare earth elements (REE) patterns indicate that the lavas are somewhat enriched in light rare earth elements (LREE), with flat heavy rare earth elements (HREE) patterns. This evidence is consistent with a spinel-bearing mantle source. The sub-parallel chondrite-normalized patterns show enrichment with differentiation, with a greater increase of LREE than HREE. The occurrence of high-magnesia basalts at 18 Ma in Sardinia appears to be correlated with and favoured by pronounced extensional tectonics at that time.

Sources and distribution of yttrium and rare earth elements in surface sediments from Tagus estuary, Portugal.

PubMed

Brito, Pedro; Prego, Ricardo; Mil-Homens, Mário; Caçador, Isabel; Caetano, Miguel

2018-04-15

The distribution and sources of yttrium and rare-earth elements (YREE) in surface sediments were studied on 78 samples collected in the Tagus estuary (SW Portugal, SW Europe). Yttrium and total REE contents ranged from 2.4 to 32mg·kg -1 and 18 to 210mg·kg -1 , respectively, and exhibited significant correlations with sediment grain-size, Al, Fe, Mg and Mn, suggesting a preferential association to fine-grained material (e.g. aluminosilicates but also Al hydroxides and Fe oxyhydroxides). The PAAS (Post-Archean Australian Shale) normalized patterns display three distinct YREE fractionation pattern groups along the Tagus estuary: a first group, characterized by medium to coarse-grained material, a depleted and almost flat PAAS-normalized pattern, with a positive anomaly of Eu, representing one of the lithogenic components; a second group, characterized mainly by fine-grained sediment, with higher shale-normalized ratios and an enrichment of LREE relative to HREE, associated with waste water treatment plant (WWTP) outfalls, located in the northern margin; and, a third group, of fine-grained material, marked by a significant enrichment of Y, a depletion of Ce and an enrichment of HREE over LREE, located near an inactive chemical-industrial complex (e.g. pyrite roast plant, chemical and phosphorous fertilizer industries), in the southern margin. The data allow the quantification of the YREE contents and its spatial distribution in the surface sediments of the Tagus estuary, identifying the main potential sources and confirming the use of rare earth elements as tracers of anthropogenic activities in highly hydrodynamic estuaries. Copyright © 2017 Elsevier B.V. All rights reserved.

Gender- and Age-Specific REE and REE/FFM Distributions in Healthy Chinese Adults

PubMed Central

Cheng, Yu; Yang, Xue; Na, Li-Xin; Li, Ying; Sun, Chang-Hao

2016-01-01

Basic data on the resting energy expenditure (REE) of healthy populations are currently rare, especially for developing countries. The aims of the present study were to describe gender- and age-specific REE distributions and to evaluate the relationships among glycolipid metabolism, eating behaviors, and REE in healthy Chinese adults. This cross-sectional survey included 540 subjects (343 women and 197 men, 20–79 years old). REE was measured by indirect calorimetry and expressed as kcal/day/kg total body weight. The data were presented as the means and percentiles for REE and the REE to fat-free mass (FFM) ratio; differences were described by gender and age. Partial correlation analysis was used to analyze the correlations between REE, tertiles of REE/FFM, and glycolipid metabolism and eating behaviors. In this study, we confirmed a decline in REE with age in women (p = 0.000) and men (p = 0.000), and we found that men have a higher REE (p = 0.000) and lower REE/FFM (p = 0.021) than women. Furthermore, we observed no associations among glycolipid metabolism, eating behaviors, and REE in healthy Chinese adults. In conclusion, the results presented here may be useful to clinicians and nutritionists for comparing healthy and ill subjects and identifying changes in REE that are related to aging, malnutrition, and chronic diseases. PMID:27598192

Gender- and Age-Specific REE and REE/FFM Distributions in Healthy Chinese Adults.

PubMed

Cheng, Yu; Yang, Xue; Na, Li-Xin; Li, Ying; Sun, Chang-Hao

2016-09-01

Basic data on the resting energy expenditure (REE) of healthy populations are currently rare, especially for developing countries. The aims of the present study were to describe gender- and age-specific REE distributions and to evaluate the relationships among glycolipid metabolism, eating behaviors, and REE in healthy Chinese adults. This cross-sectional survey included 540 subjects (343 women and 197 men, 20-79 years old). REE was measured by indirect calorimetry and expressed as kcal/day/kg total body weight. The data were presented as the means and percentiles for REE and the REE to fat-free mass (FFM) ratio; differences were described by gender and age. Partial correlation analysis was used to analyze the correlations between REE, tertiles of REE/FFM, and glycolipid metabolism and eating behaviors. In this study, we confirmed a decline in REE with age in women (p = 0.000) and men (p = 0.000), and we found that men have a higher REE (p = 0.000) and lower REE/FFM (p = 0.021) than women. Furthermore, we observed no associations among glycolipid metabolism, eating behaviors, and REE in healthy Chinese adults. In conclusion, the results presented here may be useful to clinicians and nutritionists for comparing healthy and ill subjects and identifying changes in REE that are related to aging, malnutrition, and chronic diseases.

Abdominal fat sub-depots and energy expenditure: Magnetic resonance imaging study.

PubMed

Serfaty, Dana; Rein, Michal; Schwarzfuchs, Dan; Shelef, Ilan; Gepner, Yftach; Bril, Nitzan; Cohen, Noa; Shemesh, Elad; Sarusi, Benjamin; Kovsan, Julia; Kenigsbuch, Shira; Chassidim, Yoash; Golan, Rachel; Witkow, Shula; Henkin, Yaakov; Stampfer, Meir J; Rudich, Assaf; Shai, Iris

2017-06-01

We aimed to assess the association between the distinct abdominal sub-depots and resting energy expenditure (REE). We performed magnetic resonance imaging (MRI) to quantify abdominal visceral-adipose-tissue (VAT), deep-subcutaneous-adipose-tissue (deep-SAT), and superficial-subcutaneous-adipose-tissue (superficial-SAT). We measured REE by indirect-calorimetry. Non-exercise activity thermogenesis (NEAT) [1-3 metabolic equivalents (METs)] and exercise thermogenesis (activities of 4+MET S ) were estimated based on 6-days of accelerometry to assess total physical activity energy expenditure (PAEE). We studied 282 participants: 249 men [mean age = 47.4 years, body-mass-index (BMI) = 31 kg/m 2 , mean VAT proportion from total abdominal fat = 34.5%, mean superficial-SAT proportion from total abdominal fat = 24.3%] and 33 women (mean age = 51.2 years, BMI = 30.1 kg/m 2 , mean VAT proportion from total abdominal fat = 22.8%, mean superficial-SAT proportion from total abdominal fat = 37.8%). As expected, women had lower REE [by 32.4% (1488 ± 234 kcal/day vs. 1971 ± 257 kcal/day; p < 0.01)] and lower REE/kg [by 8% (19.6 ± 3 kcal/kg vs. 21.2 ± 2 kcal/kg; p < 0.01)] than men. Exercise and total PAEE were positively associated with REE/kg (p < 0.01 for both) and a positive correlation between NEAT and REE/kg was borderline (p = 0.056). Participants, in whom abdominal VAT was the dominant proportional depot, had higher REE (1964 ± 297 kcal/day vs. 1654 ± 352 kcal/day; p < 0.01) and higher REE∖kg (22.2 ± 2.3 kcal/kg/day vs. 19.6 ± 2.5 kcal/kg/day; p < 0.01) than participants in whom superficial-SAT was the largest proportional depot. In multivariate models, adjusted for age, gender and residual BMI, increased VAT proportion was independently associated with higher REE (β = 0.181; p = 0.05). Likewise, increased VAT proportion (β = 0.482; p < 0.01) remained independently associated with higher REE/kg. In this model younger age (β = -0.329; p < 0.01) was associated with higher REE/kg. Abdominal fat distribution patterns are associated with varying levels of resting energy expenditure, potentially reflecting different metabolic rates of adipose sub-depots and providing an anatomic/anthropometric link to physiological obese sub-phenotypes. Copyright © 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Rare earth elements in sedimentary phosphate deposits: Solution to the global REE crisis?

USGS Publications Warehouse

Emsbo, Poul; McLaughlin, Patrick I.; Breit, George N.; du Bray, Edward A.; Koenig, Alan E.

2015-01-01

The critical role of rare earth elements (REEs), particularly heavy REEs (HREEs), in high-tech industries has created a surge in demand that is quickly outstripping known global supply and has triggered a worldwide scramble to discover new sources. The chemical analysis of 23 sedimentary phosphate deposits (phosphorites) in the United States demonstrates that they are significantly enriched in REEs. Leaching experiments using dilute H2SO4 and HCl, extracted nearly 100% of their total REE content and show that the extraction of REEs from phosphorites is not subject to the many technological and environmental challenges that vex the exploitation of many identified REE deposits. Our data suggest that phosphate rock currently mined in the United States has the potential to produce a significant proportion of the world's REE demand as a byproduct. Importantly, the size and concentration of HREEs in some unmined phosphorites dwarf the world's richest REE deposits. Secular variation in phosphate REE contents identifies geologic time periods favorable for the formation of currently unrecognized high-REE phosphates. The extraordinary endowment, combined with the ease of REE extraction, indicates that such phosphorites might be considered as a primary source of REEs with the potential to resolve the global REE (particularly for HREE) supply shortage.

Petrogenesis of Early Cretaceous dioritic dikes in the Shanyang-Zhashui area, South Qinling, central China: Evidence for partial melting of thickened lower continental crust

NASA Astrophysics Data System (ADS)

Chen, Lei; Yan, Zhen; Wang, Zongqi; Wang, Kunming

2018-06-01

The dioritic dikes distributed in the Shanyang-Zhashui area of the South Qinling region play an important role in understanding the deep magmatic processes and tectonic evolution during the orogenic process. The zircon Usbnd Pb ages of the dioritic dikes indicate that they were emplaced at ∼144 Ma and therefore postdate the dikes that formed in the intracontinental orogenic background after the continental collision between the North China Block (NCB) and the South China Block (SCB). The dioritic dikes have SiO2 contents of 56.86-64.93 wt%; K2O contents of 1.65-3.21 wt%; low MgO (1.50-2.66 wt%), Y (14.4-25.5 ppm) and heavy rare earth element (HREE) contents; low Mg# values (39.9-49); high Sr contents (528-4833 ppm); and high Sr/Y ratios (32.8-189). They exhibit highly fractionated REE and flat HREE patterns, strong enrichment in large ion lithophile elements (LILEs; e.g., Rb, Ba, and U) and depletion in high field strength elements (HFSEs) (e.g., Nb), as well as positive Sr and negative Ti anomalies. Furthermore, these dioritic dikes exhibit (87Sr/86Sr)i ratios ranging from 0.7048 to 0.7083, εNd(t) values ranging from -3.3 to -1.4, and εHf(t) values ranging from -4.1 to 1.6. The geochemical patterns of the dioritic dikes indicate that they possess adakitic characteristics. Moreover, the low MgO contents, Mg# values, Ni contents, Th/Ce ratios, and Srsbnd Ndsbnd Hf isotopic features all indicate that these dioritic dikes were generated by the partial melting of thickened mafic lower crust. The high La/Yb and Sr/Y ratios, low Y and Yb contents, absence of significant Eu anomalies, flat HREE patterns, and low Nb/Ta ratios of these rocks suggest that the adakitic melts were derived from the melting of garnet-bearing amphibolite. The geochronologic, elemental and isotopic evidence suggests that the dioritic dikes may have formed in a locally extensional environment within an overall N-S compressional setting or during the transition from compressional to extensional environments in the Early Cretaceous. This process resulted in the upwelling of the asthenospheric or lithospheric mantle, causing partial melting of the mafic lower crust and forming the adakitic dioritic melts.

Health effects and toxicity mechanisms of rare earth elements-Knowledge gaps and research prospects.

PubMed

Pagano, Giovanni; Guida, Marco; Tommasi, Franca; Oral, Rahime

2015-05-01

In the recent decades, rare earth elements (REE) have undergone a steady spread in several industrial and medical applications, and in agriculture. Relatively scarce information has been acquired to date on REE-associated biological effects, from studies of bioaccumulation and of bioassays on animal, plant and models; a few case reports have focused on human health effects following occupational REE exposures, in the present lack of epidemiological studies of occupationally exposed groups. The literature is mostly confined to reports on few REE, namely cerium and lanthanum, whereas substantial information gaps persist on the health effects of other REE. An established action mechanism in REE-associated health effects relates to modulating oxidative stress, analogous to the recognized redox mechanisms observed for other transition elements. Adverse outcomes of REE exposures include a number of endpoints, such as growth inhibition, cytogenetic effects, and organ-specific toxicity. An apparent controversy regarding REE-associated health effects relates to opposed data pointing to either favorable or adverse effects of REE exposures. Several studies have demonstrated that REE, like a number of other xenobiotics, follow hormetic concentration-related trends, implying stimulatory or protective effects at low levels, then adverse effects at higher concentrations. Another major role for REE-associated effects should be focused on pH-dependent REE speciation and hence toxicity. Few reports have demonstrated that environmental acidification enhances REE toxicity; these data may assume particular relevance in REE-polluted acidic soils and in REE mining areas characterized by concomitant REE and acid pollution. The likely environmental threats arising from REE exposures deserve a new line of research efforts. Copyright © 2015 Elsevier Inc. All rights reserved.

Systematic Investigation of REE Mobility and Fractionation During Continental Shale Weathering Along a Climate Gradient

NASA Astrophysics Data System (ADS)

Jin, L.; Ma, L.; Dere, A. L. D.; White, T.; Brantley, S. L.

2014-12-01

Rare earth elements (REE) have been identified as strategic natural resources and their demand in the United States is increasing rapidly. REE are relatively abundant in the Earth's crust, but REE deposits with minable concentrations are uncommon. One recent study has pointed to the deep-sea REE-rich muds in the Pacific Ocean as a new potential resource, related to adsorption and concentration of REE from seawater by hydrothermal iron-oxyhydroxides and phillipsite (Kato et al., 2010). Finding new REE deposits will be facilitated by understanding global REE cycles: during the transformation of bedrock into soils, REEs are leached into natural waters and transported to oceans. At present, the mechanisms and factors controlling release, transport, and deposition of REE - the sources and sinks - at Earth's surface remain unclear. Here, we systematically studied soil profiles and bedrock in seven watersheds developed on shale bedrock along a climate transect in the eastern USA, Puerto Rico and Wales to constrain the mobility and fractionation of REE during chemical weathering processes. In addition, one site on black shale (Marcellus) bedrock was included to compare behaviors of REEs in organic-rich vs. organic-poor shale end members under the same environmental conditions. Our investigation focused on: 1) the concentration of REEs in gray and black shales and the release rates of REE during shale weathering, 2) the biogeochemical and hydrological conditions (such as redox, dissolved organic carbon, and pH) that dictate the mobility and fractionation of REEs in surface and subsurface environments, and 3) the retention of dissolved REEs on soils, especially onto secondary Fe/Al oxyhydroxides and phosphate mineral phases. This systematic study sheds light on the geochemical behaviors and environmental pathways of REEs during shale weathering along a climosequence.

Bacterial dissolution of fluorapatite as a possible source of elevated dissolved phosphate in the environment

NASA Astrophysics Data System (ADS)

Feng, Mu-hua; Ngwenya, Bryne T.; Wang, Lin; Li, Wenchao; Olive, Valerie; Ellam, Robert M.

2011-10-01

In order to understand the contribution of geogenic phosphorus to lake eutrophication, we have investigated the rate and extent of fluorapatite dissolution in the presence of two common soil bacteria ( Pantoea agglomerans and Bacillus megaterium) at T = 25 °C for 26 days. The release of calcium (Ca), phosphorus (P), and rare earth elements (REE) under biotic and abiotic conditions was compared to investigate the effect of microorganism on apatite dissolution. The release of Ca and P was enhanced under the influence of bacteria. Apatite dissolution rates obtained from solution Ca concentration in the biotic reactors increased above error compared with abiotic controls. Chemical analysis of biomass showed that bacteria scavenged Ca, P, and REE during their growth, which lowered their fluid concentrations, leading to apparent lower release rates. The temporal evolution of pH in the reactors reflected the balance of apatite weathering, solution reactions, bacterial metabolism, and potentially secondary precipitation, which was implied in the variety of REE patterns in the biotic and abiotic reactors. Light rare earth elements (LREE) were preferentially adsorbed to cell surfaces, whereas heavy rare earth elements (HREE) were retained in the fluid phase. Decoupling of LREE and HREE could possibly be due to preferential release of HREE from apatite or selective secondary precipitation of LREE enriched phosphates, especially in the presence of bacteria. When corrected for intracellular concentrations, both biotic reactors showed high P and REE release compared with the abiotic control. We speculate that lack of this correction explains the conflicting findings about the role of bacteria in mineral weathering rates. The observation that bacteria enhance the release rates of P and REE from apatite could account for some of the phosphorus burden and metal pollution in aquatic environments.

Geochemistry of Zr, Hf, and REE in a wide spectrum of Eh and water composition: The case of Dead Sea Fault system (Israel)

NASA Astrophysics Data System (ADS)

Censi, P.; Raso, M.; Yechieli, Y.; Ginat, H.; Saiano, F.; Zuddas, P.; Brusca, L.; D'Alessandro, W.; Inguaggiato, C.

2017-03-01

Along the Jordan Valley-Dead Sea Fault area several natural waters in springs, wells, and catchments occur. The chemical-physical characters of the studied waters allowed for the first time the investigation of the Zr and Hf geochemical behavior, apart from REE, extended to a wide range of Eh, temperature, salinity, and pH conditions. The results of this study indicate that the dissolved Zr and Hf distribution in natural waters is strongly influenced by redox conditions since these in turn drive the deposition of Fe-oxyhydroxides or pyrite. In oxidizing waters saturated or oversaturated in Fe-oxyhydroxides (Group 1), superchondritic Zr/Hf values are measured. On the contrary, in waters where Eh < 0 values occur (Group 2), chondritic Zr/Hf values are found. Superchondritic Zr/Hf values are produced by the preferential Hf scavenging onto Fe-oxyhydroxides that is inhibited under reducing conditions consistent with the water oversaturation relative to pyrite. Redox conditions also influence the amplitude of Ce and Eu anomalies. Oxidized Group-1 waters show negative Ce anomalies related to the oxidative Ce scavenging as CeO2 onto Fe-oxyhydroxide. Reduced Group-2 waters show positive Eu anomaly values consistent with the larger Eu2+ concentration relative to Eu3+ in these waters suggested by model calculations. The higher stability of Eu2+ with respect to its trivalent neighbors along the REE series can explain the above mentioned positive Eu anomaly values. The middle-REE enrichment observed in shale-normalized REE patterns of studied waters can be ascribed to carbonate and/or gypsum dissolution.

Comparative toxicities of selected rare earth elements: Sea urchin embryogenesis and fertilization damage with redox and cytogenetic effects.

PubMed

Pagano, Giovanni; Guida, Marco; Siciliano, Antonietta; Oral, Rahime; Koçbaş, Fatma; Palumbo, Anna; Castellano, Immacolata; Migliaccio, Oriana; Thomas, Philippe J; Trifuoggi, Marco

2016-05-01

Broad-ranging adverse effects are known for rare earth elements (REE), yet only a few studies tested the toxicity of several REE, prompting studies focusing on multi-parameter REE toxicity. Trichloride salts of Y, La, Ce, Nd, Sm, Eu and Gd were tested in Paracentrotus lividus sea urchin embryos and sperm for: (1) developmental defects in either REE-exposed larvae or in the offspring of REE-exposed sperm; (2) fertilization success; (3) mitotic anomalies in REE-exposed embryos and in the offspring of REE-exposed sperm, and (4) reactive oxygen species (ROS) formation, and malondialdehyde (MDA) and nitric oxide (NO) levels. REEs affected P. lividus larvae with concentration-related increase in developmental defects, 10(-6) to 10(-4)M, ranking as: Gd(III)>Y(III)>La(III)>Nd(III)≅Eu(III)>Ce(III)≅Sm(III). Nominal concentrations of REE salts were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). Significant increases in MDA levels, ROS formation, and NO levels were found in REE-exposed embryos. Sperm exposure to REEs (10(-5) to 10(-4)M) resulted in concentration-related decrease in fertilization success along with increase in offspring damage. Decreased mitotic activity and increased aberration rates were detected in REE-exposed embryos and in the offspring of REE-exposed sperm. REE-associated toxicity affecting embryogenesis, fertilization, cytogenetic and redox endpoints showed different activities of tested REEs. Damage to early life stages, along with redox and cytogenetic anomalies should be the focus of future REE toxicity studies. Copyright © 2016 Elsevier Inc. All rights reserved.

Hydrothermal transport and deposition of the rare earth elements by fluorine-bearing aqueous liquids

NASA Astrophysics Data System (ADS)

Migdisov, Art A.; Williams-Jones, A. E.

2014-12-01

New technologies, particularly those designed to address environmental concerns, have created a great demand for the rare earth elements (REE), and focused considerable attention on the processes by which they are concentrated to economically exploitable levels in the Earth's crust. There is widespread agreement that hydrothermal fluids played an important role in the formation of the world's largest economic REE deposit, i.e. Bayan Obo, China. Until recently, many researchers have assumed that hydrothermal transport of the REE in fluorine-bearing ore-forming systems occurs mainly due to the formation of REE-fluoride complexes. Consequently, hydrothermal models for REE concentration have commonly involved depositional mechanisms based on saturation of the fluid with REE minerals due to destabilization of REE-fluoride complexes. Here, we demonstrate that these complexes are insignificant in REE transport, and that the above models are therefore flawed. The strong association of H+ and F- as HF° and low solubility of REE-F solids greatly limit transport of the REE as fluoride complexes. However, this limitation does not apply to REE-chloride complexes. Because of this, the high concentration of Cl- in the ore fluids, and the relatively high stability of REE-chloride complexes, the latter can transport appreciable concentrations of REE at low pH. The limitation also does not apply to sulphate complexes and in some fluids, the concentration of sulphate may be sufficient to transport significant concentrations of REE as sulphate complexes, particularly at weakly acidic pH. This article proposes new models for hydrothermal REE deposition based on the transport of the REE as chloride and sulphate complexes.

Chemical systematics of the Shergotty meteorite and the composition of its parent body (Mars)

NASA Technical Reports Server (NTRS)

Laul, J. C.; Smith, M. R.; Waenke, H.; Jagoutz, E.; Dreibus, G.

1986-01-01

Sixty elements in two bulk samples of Shergotty meteorite and 30 elements in various mineral separates of Shergotty were identified, using mainly INAA and RNAA techniques. In addition, elements leached out from powdered samples of Shergotty and EETA 79001 meteorites by 0.1 N HCl, as well as the elements of their residues, were analyzed. The results have indicated that Shergotty meteorite is homogeneous in its major element composition, but heterogeneous with respect to large-ion lithophile elements, such as K, Ba, Sr, Zr, Hf, Ta, Th, and rare-earth elements (REEs). It is even more heterogeneous with respect to volatile elements, such as Cd, Te, Tl, and Bi, and the siderophiles Au and Ag. The REE patterns of the Shergotty and EETA 79001 residues are identical, indicating that the parent magmas of both meteorites are compositionally similar. However, their leachate (phosphate) patterns are different, suggesting two components for the Shergotty, one of which is similar to the EETA 79001 leachate.

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

PubMed

Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R

2015-08-18

The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

Source Evolution After Subduction Initiation as Recorded in the Izu-Bonin-Mariana Fore-arc Crust

NASA Astrophysics Data System (ADS)

Shervais, J. W.; Reagan, M. K.; Pearce, J. A.; Shimizu, K.

2015-12-01

Drilling in the Izu-Bonin-Mariana (IBM) fore-arc during IODP Expedition 352 and DSDP Leg 60 recovered consistent stratigraphic sequences of volcanic rocks reminiscent of those found in many ophiolites. The oldest lavas in these sections are "fore-arc basalts" (FAB) with ~51.5 Ma ages. Boninites began eruption approximately 2-3 m.y. later (Ishizuka et al., 2011, EPSL; Reagan et al., 2013, EPSL) and further from the trench. First results from IODP Expedition 352 and preliminary post-cruise data suggest that FAB at Sites U1440 and U1441 were generated by decompression melting during near-trench sea-floor spreading, and that fluids from the subducting slab were not involved in their genesis. Temperatures appear to have been unusually high and pressures of melting appear to have been unusually low compared to mid-ocean ridges. Spreading rates at this time appear to have been robust enough to maintain a stable melt lens. Incompatible trace element abundances are low in FAB compared to even depleted MORB. Nd and Hf Isotopic compositions published before the expedition suggest that FAB were derived from typical MORB source mantle. Thus, their extreme deletion resulted from unusually high degrees of melting immediately after subduction initiation. The oldest boninites from DSDP Site 458 and IODP Sites U1439 and U1442 have relatively high concentrations of fluid-soluble elements, low concentrations of REE, and light depleted REE patterns. Younger boninites, have even lower REE concentrations, but have U-shaped REE patterns. Our first major and trace element compositions for the FAB through boninite sequence suggests that melting pressures and temperatures decreased through time, mantle became more depleted though time, and spreading rates waned during boninite genesis. Subduction zone fluids involved in boninite genesis appear to have been derived from progressively higher temperatures and pressures over time as the subducting slab thermally matured.

Geochemical and multi-isotopic (87Sr/86Sr, 143Nd/144Nd, 238U/235U) perspectives of sediment sources, depositional conditions, and diagenesis of the Marcellus Shale, Appalachian Basin, USA

NASA Astrophysics Data System (ADS)

Phan, Thai T.; Gardiner, James B.; Capo, Rosemary C.; Stewart, Brian W.

2018-02-01

We investigate sediment sources, depositional conditions and diagenetic processes affecting the Middle Devonian Marcellus Shale in the Appalachian Basin, eastern USA, a major target of natural gas exploration. Multiple proxies, including trace metal contents, rare earth elements (REE), the Sm-Nd and Rb-Sr isotope systems, and U isotopes were applied to whole rock digestions and sequentially extracted fractions of the Marcellus shale and adjacent units from two locations in the Appalachian Basin. The narrow range of εNd values (from -7.8 to -6.4 at 390 Ma) is consistent with derivation of the clastic sedimentary component of the Marcellus Shale from a well-mixed source of fluvial and eolian material of the Grenville orogenic belt, and indicate minimal post-depositional alteration of the Sm-Nd system. While silicate minerals host >80% of the REE in the shale, data from sequentially extracted fractions reflect post-depositional modifications at the mineralogical scale, which is not observed in whole rock REE patterns. Limestone units thought to have formed under open ocean (oxic) conditions have δ238U values and REE patterns consistent with modern seawater. The δ238U values in whole rock shale and authigenic phases are greater than those of modern seawater and the upper crust. The δ238U values of reduced phases (the oxidizable fraction consisting of organics and sulfide minerals) are ∼0.6‰ greater than that of modern seawater. Bulk shale and carbonate cement extracted from the shale have similar δ238U values, and are greater than δ238U values of adjacent limestone units. We suggest these trends are due to the accumulation of chemically and, more likely, biologically reduced U from anoxic to euxinic bottom water as well as the influence of diagenetic reactions between pore fluids and surrounding sediment and organic matter during diagenesis and catagenesis.

Comparative toxicities of selected rare earth elements: Sea urchin embryogenesis and fertilization damage with redox and cytogenetic effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagano, Giovanni, E-mail: gbpagano@tin.it; Guida, Marco; Siciliano, Antonietta

Background: Broad-ranging adverse effects are known for rare earth elements (REE), yet only a few studies tested the toxicity of several REE, prompting studies focusing on multi-parameter REE toxicity. Methods: Trichloride salts of Y, La, Ce, Nd, Sm, Eu and Gd were tested in Paracentrotus lividus sea urchin embryos and sperm for: (1) developmental defects in either REE-exposed larvae or in the offspring of REE-exposed sperm; (2) fertilization success; (3) mitotic anomalies in REE-exposed embryos and in the offspring of REE-exposed sperm, and (4) reactive oxygen species (ROS) formation, and malondialdehyde (MDA) and nitric oxide (NO) levels. Results: REEs affectedmore » P. lividus larvae with concentration-related increase in developmental defects, 10{sup −6} to 10{sup −4} M, ranking as: Gd(III)>Y(III)>La(III)>Nd(III)≅Eu(III)>Ce(III)≅Sm(III). Nominal concentrations of REE salts were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). Significant increases in MDA levels, ROS formation, and NO levels were found in REE-exposed embryos. Sperm exposure to REEs (10{sup −5} to 10{sup −4} M) resulted in concentration-related decrease in fertilization success along with increase in offspring damage. Decreased mitotic activity and increased aberration rates were detected in REE-exposed embryos and in the offspring of REE-exposed sperm. Conclusion: REE-associated toxicity affecting embryogenesis, fertilization, cytogenetic and redox endpoints showed different activities of tested REEs. Damage to early life stages, along with redox and cytogenetic anomalies should be the focus of future REE toxicity studies. - Highlights: • Seven rare earth elements exerted different effects on sea urchin early life stages. • Embryo-, spermio- and mitotoxicity, and oxidative/ nitrosative stress were found. • Nominal vs. analytical REE concentrations were checked. • Comparative toxicities were evaluated for the different REE.« less

Rare earth elements in human and animal health: State of art and research priorities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagano, Giovanni, E-mail: gbpagano@tin.it; Aliberti, Francesco; Guida, Marco

Background: A number of applications have been developed using rare earth elements (REE), implying several human exposures and raising unsolved questions as to REE-associated health effects. Methods: A MedLine survey was retrieved from early reports (1980s) up to June 2015, focused on human and animal exposures to REE. Literature from animal models was selected focusing on REE-associated health effects. Results: Some REE occupational exposures, in jobs such as glass polishers, photoengravers and movie projectionists showed a few case reports on health effects affecting the respiratory system. No case-control or cohort studies of occupational REE exposures were retrieved. Environmental exposures havemore » been biomonitored in populations residing in REE mining areas, showing REE accumulation. The case for a iatrogenic REE exposure was raised by the use of gadolinium-based contrast agents for nuclear magnetic resonance. Animal toxicity studies have shown REE toxicity, affecting a number of endpoints in liver, lungs and blood. On the other hand, the use of REE as feed additives in livestock is referred as a safe and promising device in zootechnical activities, possibly suggesting a hormetic effect both known for REE and for other xenobiotics. Thus, investigations on long-term exposures and observations are warranted. Conclusion: The state of art provides a limited definition of the health effects in occupationally or environmentally REE-exposed human populations. Research priorities should be addressed to case-control or cohort studies of REE-exposed humans and to life-long animal experiments. - Highlights: • An extensive number of activities have been developed utilizing rare earth elements (REE). • The literature of REE-associated health effects in humans, and on animal studies is reviewed. • The main literature gaps are discussed, in epidemiological and in animal studies. • Prospects studies are suggested, aimed at evaluating long-term effects of REE exposures. • The relevance of REE-related hormesis, speciation and acidic pollution are discussed.« less

Petrology and Geochemistry of Tethyan Mélange and Flysch Units Adjacent to the Yarlung Zangbo Suture Zone (YZSZ), Southern Tibet

NASA Astrophysics Data System (ADS)

Dupuis, C.; Hebert, R.; Wang, C.; Li, Y.; Li, Z.

2004-05-01

Located north of the Himalayas, the E-W trending YZSZ is mainly composed of remnants of the Neo-Tethys ocean-floor and marks the suture between Indian and Eurasian plates. This project aims to define geological units immediately South of the YZSZ ophiolites : the serpentinized ophiolitic mélange, the Jurassic-Cretaceous wildflysch and the Triassic flysch. The ophiolitic mélange is characterized by ultramafic rocks, which can be divided into 3 groups. Cpx-harzburgites contain brownish aluminous spinels with Mg# of 0.7-0.75 and Cr# of 0.15-0.27. They resemble fertile abyssal peridotites with generally smooth LREE-depleted and fairly flat MREE-HREE profiles. Transitional harzburgites contain reddish spinels with Mg# of 0.57-0.66 and Cr# of 0.35-0.46. They resemble depleted abyssal or supra-subduction zone peridotites in that MREE-HREE profiles have positive slopes indicative of high degrees of partial melting. LREE profiles vary from depleted to slightly enriched, consistent with some trapped or interacting melt or aqueous fluids. Harzburgites and dunites contain dark reddish spinels with Mg# of 0.47-0.68 and Cr# of 0.40-0.63. They have U-shaped profiles characteristics of interaction between LREE-enriched melt and REE-depleted mantle residues. Spinel compositions and fractional melting modelling indicate that Cpx-harburgites may be the residues from 5-15% melting, transitional harzburgites from 15-23% melting, and harzburgites and dunites from 22-29% melting. The South Sandwich arc-basin system is considered a modern analog of initial geodynamic setting. Mafic rocks (gabbros, diabases and basalts) are ubiquitous and can be geochemically subdivided according to their source unit. LREE-depleted profiles with average (La/Yb)N of 0.5 and slight negative Nb-Ta and Ti anomalies indicate that rocks from the ophiolitic mélange formed in a back-arc basin, such as back-arc-basin mafic rocks of the Izu-Bonin Arc. REE patterns of rocks from the wildflysch are LREE-enriched with average (La/Yb)N of 5.3. These rocks are of intraplate affinity and are geochemically similar to volcanic rocks of the South Tethyan suture zone of Pakistan, which are interpreted to represent an early expression of the Réunion hotspot. Rocks from the flysch show the most LREE-enriched profiles with average (La/Yb)N of 6.9 and slight negative Nb-Ta and Ti anomalies, which suggest continental lithospheric assimilation. Similarly to volcanic rocks of the Deccan Traps, these rocks are thus interpreted to derive from an enriched mantle source of intraplate type (Réunion hotspot?), with additional contamination from the Indian continental crust (ICC). The geochemical signature of greywackes, red and black shales from the wildflysch and flysch units are all concordant with a continental passive margin setting. Despite fairly important chemical weathering, the signature was not affected by significant sedimentary recycling nor heavy-mineral accumulation. REE patterns show a LREE enrichment typical of shales and indicate an old upper CC provenance for the turbidites. Multi-element patterns indicate both mafic and felsic contributions to the source. The mafic contribution (slight positive Ti anomalies) could originate from mafic blocks of enriched intraplate geochemical affinity found in the sedimentary units, whereas the felsic contribution (slight LREE enrichment and negative NB-Ta anomalies) probably derives from remnants of evolved migmatitic batholith of the ICC.

Provenance, Source Rock Characteristics And Paleoweathering Conditions Of The Nearshore Continental Sediments Off Pondicherry, South East Coast Of India

NASA Astrophysics Data System (ADS)

Natarajan, T.; Seshachalam, S.; Ponniah, J.; Varadhan, R.; M, S.

2008-05-01

Geochemical studies, comprising major elements and trace elements, including the Rare Earth Elements (REE), have been carried out on the modern sediments of inner continental shelf representing nearshore marine environments. Concentrations were normalized with Chondrite and PAAS show LREE enriched and flat HREE patterns with slight positive Eu anomaly which is due to the influence of feldspar rich source materials. The LREE enriched and flat HREE patterns with positive Eu anomaly have been considered as the typical character of post- Archaean Sediments. The La/Th ratio ranges from 1.66 to 8.84 with an average value of 4.09, which indicates a heterogenitic source for the sediments of the study area. The La-Th-Sc ternary plot suggests all the samples fall close to the field dominated by tonalite to granite and away from the basalt and komatiite compositions and appear to be derived from sources enriched in felsic components. The transition metal ratios such as Cr/V, Ni/CO and V/Ni indicate both Archaean and Post-Archaean nature to the sediments indicating that the sediments have been derived from heterogenitic sources. The ternary diagram plot of Th-Hf-Co and La-Th-Sc falls in the field of upper continental crust of post Archaean age. This clearly indicates the terrestrial source for the sediments from the nearby landmass. The data are slightly offset from the upper crustal composition away from the Hf apex. This is probably a result of Zircon concentration. Geochemical data have also helped in ascertaining the weathering trends. The Chemical Index of Alteration (CIA) has been used to quantify the degree of weathering. The calculated CIA values for sediments demonstrate both low CIA values of less than 50 percent (low silicate weathering) and intermediate CIA values (60-70 percent) indicating that the sediments are possibly the product of sedimentary and metasedimentary rocks that have undergone intermediate chemical weathering. On an A—CN—K diagram, the data fall closer to the trend parallel to Al2O3 (CaO*+Na2O) join, suggesting that the sediments represent weathered products from granite and charnockite.

Green glass vitrophyre 78526 - An impact of very low-Ti mare basalt composition

NASA Technical Reports Server (NTRS)

Warner, R. D.; Taylor, G. J.; Kiel, K.; Planner, H. H.; Nehru, C. E.; Ma, M.-S.; Schmitt, R. A.

1978-01-01

Rake sample 78526 is an 8.77 g rock consisting primarily of vitrophyric pale green glass with subordinate mineral and lithic relics. Petrographic and compositional evidence leads to the following conclusions: (1) the bulk composition represents that of a mixture formed by impact melting of at least two different textural and compositional varieties of VLT mare basalt that are now present in the rock as lithic relics and a poorly defined low-Ti mare basalt component observed in thin section only in the form of isolated mineral relics; (2) the admixed VLT mare basalts had REE abundances lower than those found in other mare basalts (but probably higher than emerald green glass) and REE patterns showing significant enrichment of the heavy relative to light REE's, suggesting that they were derived by comparatively high degrees of partial melting of a clinopyroxene-rich source region; and (3) the impact melt supercooled to produce the vitrophyre, with rather sharply contrasting textural domains present in the vitrophyre resulting from differences in nucleation kinetics and degrees of supercooling in various portions of the sample.

Experimental mineral/liquid partition coefficients of the rare earth elements /REE/, Sc and Sr for perovskite, spinel and melilite

NASA Technical Reports Server (NTRS)

Nagasawa, H.; Schreiber, H. D.; Morris, R. V.

1980-01-01

Experimental determinations of the mineral/liquid partition coefficients of REE (La, Sm, Eu, Gd, Tb, Yb and Lu), Sc and Sr are reported for the minerals perovskite, spinel and melilite in synthetic systems. Perovskite concentrates light REE with respect to the residual liquid but shows no preference for heavy REE. Spinel greatly discriminates against the incorporation of REE, especially light REE, into its crystal structure. The partition of REE into melilite from a silicate liquid is quite dependent upon both the bulk melt and melilite solid-solution (gehlenite and akermanite components) compositions. As such, melilite can be enriched in REE or will reject REE with corresponding strong negative or strong positive Eu anomalies, respectively.

Geology and market-dependent significance of rare earth element resources

NASA Astrophysics Data System (ADS)

Simandl, G. J.

2014-12-01

China started to produce rare earth elements (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare earth element export quotas first introduced by the Chinese government in the early 2000s were severely reduced in 2010 and 2011. This led to strong government-created disparity between prices within China and the rest of the world. Industrialized countries identified several REEs as strategic metals. Because of rapid price increases of REE outside of China, we have witnessed a world-scale REE exploration rush. The REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, monazite ± apatite veins, ion adsorption clays, placers, and some deep ocean sediments. REE could also be derived as a by-product of phosphate fertilizer production, U processing, mining of Ti-Zr-bearing placers, and exploitation of Olympic Dam subtype iron oxide copper gold (IOCG) deposits. Currently, REEs are produced mostly from carbonatite-related deposits, but ion adsorption clay deposits are an important source of heavy REE (HREE). Small quantities of REE are derived from placer deposits and one peralkaline intrusion-related deposit. The ideal REE development targets would be located in a politically stable jurisdiction with a pro-mining disposition such as Canada and Australia. REE grade, HREE/light REE (LREE) ratio of the mineralization, tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen potential development projects. As REEs are considered strategic metals from economic, national security, and environmental points of view, technical and economic parameters alone are unlikely to be used in REE project development decision-making. Recycling of REE is in its infancy and unless legislated, in the short term, it is not expected to contribute significantly to the supply of REE.

Bacterial Cell Surface Adsorption of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Jiao, Y.; Park, D.; Reed, D.; Fujita, Y.; Yung, M.; Anderko, A.; Eslamimanesh, A.

2015-12-01

Rare earth elements (REE) play a critical role in many emerging clean energy technologies, including high-power magnets, wind turbines, solar panels, hybrid/electric vehicle batteries and lamp phosphors. In order to sustain demand for such technologies given current domestic REE shortages, there is a need to develop new approaches for ore processing/refining and recycling of REE-containing materials. To this end, we have developed a microbially-mediated bioadsorption strategy with application towards enrichment of REE from complex mixtures. Specifically, the bacterium Caulobacter crescentus was genetically engineered to display lanthanide binding tags (LBTs), short peptides that possess high affinity and specificity for rare earth elements, on its cell surface S-layer protein. Under optimal conditions, LBT-displayed cells adsorbed greater than 5-fold more REE than control cells lacking LBTs. Competition binding experiments with a selection of REEs demonstrated that our engineered cells could facilitate separation of light- from heavy- REE. Importantly, binding of REE onto our engineered strains was much more favorable compared to non-REE metals. Finally, REE bound to the cell surface could be stripped off using citrate, providing an effective and non-toxic REE recovery method. Together, this data highlights the potential of our approach for selective REE enrichment from REE containing mixtures.

Fulvic acid like organic compounds control nucleation of marine calcite under suboxic conditions

NASA Astrophysics Data System (ADS)

Neuweiler, Fritz; D'Orazio, Valeria; Immenhauser, Adrian; Geipel, Gerhard; Heise, Karl-Heinz; Cocozza, Claudio; Miano, Teodoro M.

2003-08-01

Intracrystalline organic compounds, enclosed within in situ precipitated marine microcrystalline calcite (automicrite), might represent either an inclusion or the catalyst of such precipitation. We use evidence from a Lower Cretaceous deep-water carbonate mound to show (1) the original source, (2) the degree of condensation, (3) the redox conditions involved, and (4) the catalytic role of natural organic matter for the precipitation of automicrite. Fluorescence spectrometry of the intracrystalline organic fraction extracted from these carbonates identifies a marine fulvic acid like organic compound with a low degree of polycondensation. This finding points to a temporal correlation of the initial stage of geopolymer formation with the precipitation of automicrite. Furthermore, the rare earth element (REE) distribution patterns in the mineral show a consistent positive Ce anomaly, suggesting an episode of reductive dissolution of iron-manganese oxyhydroxides during automicrite formation. In general, a relative enrichment of middle-weight REEs is observed, resulting in a convex distribution pattern typical for, e.g., phosphate concretions or humic acid material. By merging the results of spectrometry and REE geochemistry we thus conclude that the marine calcite precipitation was catalyzed by marine fulvic acid like compounds during the early stages of humification under suboxic conditions. This indicates that humification, driven by the presence of a benthic biomass, is more important for calcite authigenesis than any site-specific microbial metabolism. The Neoproterozoic rise of carbonate mounds supports this hypothesis; there is molecular evidence for early metazoan divergence then, but not for a major evolutionary episode of microorganisms.

Partitioning in REE-saturating minerals - Theory, experiment, and modelling of whitlockite, apatite, and evolution of lunar residual magmas

NASA Technical Reports Server (NTRS)

Jolliff, Bradley L.; Haskin, Larry A.; Colson, Russell O.; Wadhwa, Meenakshi

1993-01-01

Compositions, including REEs determined by ion microprobe, of apatite and whitlockite in lunar rock assemblages rich in incompatible trace elements, are presented. Concentrations of REEs in lunar whitlockites are high, ranging from about 1.2 to 2.1 REEs (lanthanides + Y) per 56 oxygens. This slightly exceeds the level of two REE atoms per 56 oxygens at which the dominant substitution theoretically becomes saturated. This saturation effect leads to whitlockite REE(3+) D values at typical lunar whitlockite REE concentrations which are 30-40 percent lower than the D values at low concentrations. The halogen-to-phosphorous ratio in lunar melts is a key factor determining the REE distribution with crystalline assemblages. As long as P and REE concentrations of melts are in KREEP-like proportions, one or both of the phosphates will saturate in melts at similar REE concentrations.

Joint Use of the MAB-II and MicroCog for Improvements in the Clinical and Neuropsychological Screening and Aeromedical Waiver Process of Rated USAF Pilots

DTIC Science & Technology

2010-01-01

medical flight screening and the aeromedical waiver process ( Olea & Ree, 1994; Ree & Carretta, 1996; Ree, Carretta, & Teachout, 1995). Currently, the...Student pilots with high scores on ability tests are more likely to complete training ( Olea & Ree, 1994; Ree & Carretta, 1996; Ree, Carretta, & Teachout...Matrix differential calculus with applications in statistics and econometrics. New York, NY: John Wiley. Olea , M., & Ree, M.J. (1994

Origins of mass-dependent and mass-independent Ca isotope variations in meteoritic components and meteorites

NASA Astrophysics Data System (ADS)

Bermingham, K. R.; Gussone, N.; Mezger, K.; Krause, J.

2018-04-01

The Ca isotope composition of meteorites and their components may vary due to mass-dependent and/or -independent isotope effects. In order to evaluate the origin of these effects, five amoeboid olivine aggregates (AOAs), three calcium aluminum inclusions (CAIs), five chondrules (C), a dark inclusion from Allende (CV3), two dark fragments from North West Africa 753 (NWA 753; R3.9), and a whole rock sample of Orgueil (CI1) were analyzed. This is the first coupled mass-dependent and -independent Ca isotope dataset to include AOAs, a dark inclusion, and dark fragments. Where sample masses permit, Ca isotope data are reported with corresponding petrographic analyses and rare earth element (REE) relative abundance patterns. The CAIs and AOAs are enriched in light Ca isotopes (δ44/40Ca -5.32 to +0.72, where δ44/40Ca is reported relative to SRM 915a). Samples CAI 5 and AOA 1 have anomalous Group II REE patterns. These REE and δ44/40Ca data suggest that the CAI 5 and AOA 1 compositions were set via kinetic isotope fractionation during condensation and evaporation. The remaining samples show mass-dependent Ca isotope variations which cluster between δ44/40Ca +0.53 and +1.59, some of which are coupled with unfractionated REE abundance patterns. These meteoritic components likely formed through the coaccretion of the evaporative residue and condensate following Group II CAI formation or their chemical and isotopic signatures were decoupled (e.g., via nebular or parent-body alteration). The whole rock sample of Orgueil has a δ44/40Ca +0.67 ± 0.18 which is in agreement with most published data. Parent-body alteration, terrestrial alteration, and variable sampling of Ca-rich meteoritic components can have an effect on δ44/40Ca compositions in whole rock meteorites. Samples AOA 1, CAI 5, C 2, and C 4 display mass-independent 48/44Ca anomalies (ε48/44Ca +6 to +12) which are resolved from the standard composition. Other samples measured for these effects (AOA 5, CAI 1, CAI 2, C 3, D 1, D 2, D 3) possess the same 48/44Ca isotope composition as the standard within analytical uncertainty. These data indicate a heterogeneous distribution of 48Ca in the early solar nebula during formation of CAIs, AOAs, and chondrules. In a ε48/44Ca vs. δ44/40Ca plot, no strong correlation is evident which suggests that the thermal processing event which caused a heterogeneous distribution of ε48/44Ca in the solar nebula is unlikely to be directly related to the thermal processing event that caused coupled REE and Ca mass-dependent isotopic fractionation in meteoritic components.

Compositional heterogeneity of the Sugarloaf melilite nephelinite flow, Honolulu Volcanics, Hawai'i

NASA Astrophysics Data System (ADS)

Clague, David A.; Frey, Frederick A.; Garcia, Michael O.; Huang, Shichun; McWilliams, Michael; Beeson, Melvin H.

2016-07-01

The Sugarloaf flow is a melilite nephelinite erupted from the Tantalus rift during rejuvenated-stage volcanism on O'ahu, the Honolulu Volcanics. The flow ponded in Mānoa Valley forming a ∼15 m thick flow which was cored and sampled in a quarry. Nepheline from a pegmatoid segregation in the flow yielded a 40Ar-39Ar age of 76 ka. This age, combined with others, indicates that the Tantalus rift eruptions are some of the youngest on O'ahu. Honolulu Volcanics erupt on average about every 35-40 ka indicating that future eruptions are possible. We evaluated the compositional variability of 19 samples from the flow, including 14 from the core. Twelve samples are representative of the bulk flow, four are dark- or light-colored variants, one is a heavy rare earth element (REE)-enriched pegmatoid, and two visually resemble the bulk flow, but have chemical characteristics of the dark and light variants. Our objective was to determine intraflow heterogeneity in mineralogy and composition. Variable abundances of Na2O, K2O, Sr, Ba, Rb, Pb and U in the flow were caused by post-eruptive mobility in a vapor phase, most likely during or soon after flow emplacement, and heterogeneous deposition of secondary calcite and zeolites. Relative to fine-grained samples, a pegmatoid vein that crosscuts the flow is enriched in incompatible trace elements except Sr and TiO2. Element mobility after eruption introduced scatter in trace element ratios including light-REE/heavy-REE, and all ratios involving mobile elements K, Rb, Ba, Sr, Pb, and U. Lavas from some of the 37 Honolulu Volcanics vents have crosscutting REE patterns in a primitive mantle-normalized plot. Such patterns have been interpreted to reflect variable amounts of residual garnet during partial melting. Previous studies of lavas from different vents concluded that garnet, phlogopite, amphibole, and Fe-Ti oxides were residual phases of the partial melting processes that created the Honolulu Volcanics (Clague and Frey, 1982; Yang et al., 2003). However post-eruptive processes in the Sugarloaf flow also produced crossing REE patterns. Eruptions on the Tantalus rift, including the Sugarloaf flow, produced volatile- and crystal-rich ash with interstitial glass and melt inclusions in olivine containing 4.2-6.4 wt% MgO compared to the flow average of 11.8 wt%. This flow erupted as a partially crystallized viscous magma at least 100 °C below its liquidus. The slow advance and cooling of the 15-m thick 'a' ā low promoted the segregation of pegmatoids, formation of light and dark bands with differing proportions of melilite and clinopyroxene, and induced volatile-enhanced mobility of incompatible elements.

The Evolution of the Protoplanetary Disk Recorded by Nucleosynthetic Isotope Variations of Variable Stellar Origin in Refractory Inclusions

NASA Astrophysics Data System (ADS)

Schönbächler, M.; Lai, Y.-J.; Henshall, T.; Fehr, M. A.; Cook, D. L.; Bullock, E. S.

2017-07-01

New CAI data confirm the homogeneous distribution of the short-lived p-process isotope 92Nb in the early solar system with the exception of CAIs with group II REE pattern that show increased 92Nb abundances.

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction

DOE PAGES

Kim, Daejin; Powell, Lawrence E.; Delmau, Lætitia H.; ...

2015-06-24

In this paper, the rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acidmore » solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. Finally, the resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.« less

REE in the Great Whale River estuary, northwest Quebec

NASA Technical Reports Server (NTRS)

Goldstein, Steven J.; Jacobsen, Stein B.

1988-01-01

A report on REE concentrations within the estuary of the Great Whale River in northwest Quebec and in Hudson Bay is given, showing concentrations which are less than those predicted by conservative mixing of seawater and river water, indicating removal of REE from solution. REE removal is rapid, occurring primarily at salinities less than 2 percent and ranges from about 70 percent for light REE to no more than 40 percent for heavy REE. At low salinity, Fe removal is essentially complete. The shape of Fe and REE vs. salinity profiles is not consistent with a simple model of destabilization and coagulation of Fe and REE-bearing colloidal material. A linear relationship between the activity of free ion REE(3+) and pH is consistent with a simple ion-exchange model for REE removal. Surface and subsurface samples of Hudson Bay seawater show high REE and La/Yb concentrations relative to average seawater, with the subsurface sample having a Nd concentration of 100 pmol/kg and an epsilon(Nd) of -29.3; characteristics consistent with river inputs of Hudson Bay. This indicates that rivers draining the Canadian Shield are a major source of nonradiogenic Nd and REE to the Atlantic Ocean.

Are Predictive Equations for Estimating Resting Energy Expenditure Accurate in Asian Indian Male Weightlifters?

PubMed

Joseph, Mini; Gupta, Riddhi Das; Prema, L; Inbakumari, Mercy; Thomas, Nihal

2017-01-01

The accuracy of existing predictive equations to determine the resting energy expenditure (REE) of professional weightlifters remains scarcely studied. Our study aimed at assessing the REE of male Asian Indian weightlifters with indirect calorimetry and to compare the measured REE (mREE) with published equations. A new equation using potential anthropometric variables to predict REE was also evaluated. REE was measured on 30 male professional weightlifters aged between 17 and 28 years using indirect calorimetry and compared with the eight formulas predicted by Harris-Benedicts, Mifflin-St. Jeor, FAO/WHO/UNU, ICMR, Cunninghams, Owen, Katch-McArdle, and Nelson. Pearson correlation coefficient, intraclass correlation coefficient, and multiple linear regression analysis were carried out to study the agreement between the different methods, association with anthropometric variables, and to formulate a new prediction equation for this population. Pearson correlation coefficients between mREE and the anthropometric variables showed positive significance with suprailiac skinfold thickness, lean body mass (LBM), waist circumference, hip circumference, bone mineral mass, and body mass. All eight predictive equations underestimated the REE of the weightlifters when compared with the mREE. The highest mean difference was 636 kcal/day (Owen, 1986) and the lowest difference was 375 kcal/day (Cunninghams, 1980). Multiple linear regression done stepwise showed that LBM was the only significant determinant of REE in this group of sportspersons. A new equation using LBM as the independent variable for calculating REE was computed. REE for weightlifters = -164.065 + 0.039 (LBM) (confidence interval -1122.984, 794.854]. This new equation reduced the mean difference with mREE by 2.36 + 369.15 kcal/day (standard error = 67.40). The significant finding of this study was that all the prediction equations underestimated the REE. The LBM was the sole determinant of REE in this population. In the absence of indirect calorimetry, the REE equation developed by us using LBM is a better predictor for calculating REE of professional male weightlifters of this region.

Uptake of Germanium and Rare Earth Elements (La, Gd, Er, Nd) by white mustard (Brassica alba L.) and common millet (Panicum milliaceum L.) as affected by Phosphorus Nutrition

NASA Astrophysics Data System (ADS)

Zill, Juliane; Wiche, Oliver

2015-04-01

The effect of phosphate nutrition is important due to the future usage of fertilizer treatment in phytomining experiments e.g. in accumulation of the economically important rare earth elements (REE). It is expected that the trivalent charge of REE will result in complexation with phosphate and REEs could be immobilized and not further bioavailable for plants which would cause losses of REE concentration in biomass. To investigate this influence on lanthanum, neodymium, gadolinium and erbium two plant species Brassica alba (white mustard) and Panicum miliaceum (common millet) were cultured in a greenhouse study. The plants were cultivated onto two different substrates and were poured with modified REE and phosphate solutions within an eight-week period. The concentrations of REE in soil, soil solution and plant samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results show an increase of concentration of REE with increasing levels of element solution applied for both species. REE accumulations are elevated in roots and decrease in the order of roots> leaves> stem> fruit/blossom. Brassica accumulated more REE in root whereas Panicum showed higher REE concentrations in leaves. Exposure to increased phosphate addition did not significantly change the concentrations of REE in both plant species yet the REE concentrations in leaves slightly decreased with increasing phosphate addition. For root and stem no precise trend could be determined. It is most likely that REEs precipitate with phosphate on root surfaces and in the roots. The bioavailability of REE to plants is affected by complexation processes of REEs with phosphate in the rhizosphere. The results indicate that phosphate application plays an important role on REE uptake by roots and accumulation in different parts of a plant and it might have an influence on translocation of REE within the plant.

Assessing trace element diffusion models in fossil and sub-fossil bone

NASA Astrophysics Data System (ADS)

Suarez, C. A.; Kohn, M. J.

2012-12-01

Three different diffusion models have been proposed to explain trace element uptake during fossilization of bone: diffusion-adsorption (DA), diffusion-recrystallization (DR), and double-medium diffusion (DMD). Theoretically, differences in trace element profiles, particularly the rare earth elements (REE) and U, can discriminate among these possibilities. In this study, we tested which model best explains natural samples by analyzing trace element profiles in natural bone using laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Fossil bones ranging in age from a few ka to over 100 Ma were analyzed along traverses from the outer cortical edge to the inner marrow cavity margin. Forty major, minor and trace elements were analyzed, notably Ca, P, transition metals, Sr, Ba, REE, U, Th and Pb. Spatial and analytical resolutions were ~10 μm and ~100 ppb respectively. Many specimens show commonly observed exponential decreases in REE from the outer edge and marrow cavity, with relatively homogeneous U distributions. Yet, most significantly, specimens from American Falls (last interglacial) and Duck Point (last glacial maximum) show distinctive U plateaus adjacent to the outer and inner cortical bone margins. Whereas exponential profiles can be produced by different uptake processes, such plateaus are diagnostic of a DR mechanism. Our work is consistent with recent investigation of trace element diffusivities in modern fresh and deproteinated bone. These studies show similar diffusion rates for REE and U, so the profound disparity in U vs. REE profiles in most fossils cannot result solely from differences in volume diffusion within the context of DA and DMD. Rather, as a recrystallization front propagates into bone, the bone appears to encode changing soil water compositions with earlier vs. later compositions reflected in the bone margin vs. interior. Soil water U concentrations apparently remain nearly fixed during fossilization, whereas REE are rapidly stripped from the surrounding matrix, leading to nearly homogeneous U vs. steep REE profiles. However in our Pleistocene bones (American Falls and Duck Point), changes to U concentrations on the bone margin reveal more complex changes to boundary compositions, and eliminate both DA and DMD (alone) as the dominant mechanisms of trace element uptake. Our work reconciles disparate zoning patterns observed in fossil bone, and simplifies interpretations of soil or sediment water chemistry, but complicates U-series dating of fossils.

Rare earth elements in human and animal health: State of art and research priorities.

PubMed

Pagano, Giovanni; Aliberti, Francesco; Guida, Marco; Oral, Rahime; Siciliano, Antonietta; Trifuoggi, Marco; Tommasi, Franca

2015-10-01

A number of applications have been developed using rare earth elements (REE), implying several human exposures and raising unsolved questions as to REE-associated health effects. A MedLine survey was retrieved from early reports (1980s) up to June 2015, focused on human and animal exposures to REE. Literature from animal models was selected focusing on REE-associated health effects. Some REE occupational exposures, in jobs such as glass polishers, photoengravers and movie projectionists showed a few case reports on health effects affecting the respiratory system. No case-control or cohort studies of occupational REE exposures were retrieved. Environmental exposures have been biomonitored in populations residing in REE mining areas, showing REE accumulation. The case for a iatrogenic REE exposure was raised by the use of gadolinium-based contrast agents for nuclear magnetic resonance. Animal toxicity studies have shown REE toxicity, affecting a number of endpoints in liver, lungs and blood. On the other hand, the use of REE as feed additives in livestock is referred as a safe and promising device in zootechnical activities, possibly suggesting a hormetic effect both known for REE and for other xenobiotics. Thus, investigations on long-term exposures and observations are warranted. The state of art provides a limited definition of the health effects in occupationally or environmentally REE-exposed human populations. Research priorities should be addressed to case-control or cohort studies of REE-exposed humans and to life-long animal experiments. Copyright © 2015 Elsevier Inc. All rights reserved.

Rare earth element selenochemistry of immiscible liquids and zircon at Apollo 14 - An ion probe study of evolved rocks on the moon

NASA Technical Reports Server (NTRS)

Snyder, Gregory A.; Taylor, Lawrence A.; Crozaz, Ghislaine

1993-01-01

Results are presented of trace-element analyses of three lunar zircons. The major-element and REE compositions were determined using electron microprobes, and a correction was made for zircon for Zr-Si-O molecular interferences in the La to Pr mass region. The three zircons were found to exhibit similar REE abundances and patterns. Results of the analyses confirm earlier studies (Hess et al., 1975; Watson, 1976; Neal and Taylor, 1989) on the partitioning behavior of trace elements in immiscible liquid-liquid pairs. The results also support the postulated importance of silicate liquid immiscibility in the differentiation of the upper mantle and crust of the moon.

Predictive Validity of the Air Force Officer Qualifying Test for USAF Air Battle Manager Training Performance

DTIC Science & Technology

2008-09-01

performance criteria including passing/failing training, training grades, class rank (Carretta & Ree, 2003; Olea & Ree, 1994), and several non...are consistent with prior validations of the AFOQT versus academic performance criteria in pilot (Carretta & Ree, 1995; Olea & Ree, 1994; Ree...Carretta, & Teachout, 1995)) and navigator ( Olea & Ree, 1994) training. Subsequent analyses took three different approaches to examine the

Rare earth elements in human hair from a mining area of China.

PubMed

Wei, Binggan; Li, Yonghua; Li, Hairong; Yu, Jiangping; Ye, Bixiong; Liang, Tao

2013-10-01

Rare earth minerals have been mined for more than 50 years in Inner Mongolia of China. In the mining area rare earth elements (REE) may be significantly accumulated in humans. Therefore, the aim of this paper is to characterize the REE concentrations in hair of local residents. REE concentrations in hair of 118 subjects were determined. The results showed that the mean concentrations of the determined REE in the hair of both females and males were usually higher from mining area than from control area. The mean concentrations of all the fifteen REE were much higher in hair of males than in hair of females from mining area. This suggested that males might be more sensitive to REE than females. In addition, the mean contents of the REE in hair of miners, particularly light REE (La, Ce, Pr and Nd), were usually much higher than the values in hair of non-miners from both mining area and control area, indicating that the miners were exposed to higher concentrations of REE in occupational environment. Among age groups, the relationships between REE concentrations and age groups showed that more and more concentrations of light REE accumulated in body of both females and males with age until 60 years, while heavy REE concentrations decreased with age in males who were exposed to low concentrations of heavy REE. Copyright © 2013 Elsevier Inc. All rights reserved.

Calcite and dolomite in intrusive carbonatites. II. Trace-element variations

NASA Astrophysics Data System (ADS)

Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Couëslan, Christopher; Yang, Panseok

2016-04-01

The composition of calcite and dolomite from several carbonatite complexes (including a large set of petrographically diverse samples from the Aley complex in Canada) was studied by electron-microprobe analysis and laser-ablation inductively-coupled-plasma mass-spectrometry to identify the extent of substitution of rare-earth and other trace elements in these minerals and the effects of different igneous and postmagmatic processes on their composition. Analysis of the newly acquired and published data shows that the contents of rare-earth elements (REE) and certain REE ratios in magmatic calcite and dolomite are controlled by crystal fractionation of fluorapatite, monazite and, possibly, other minerals. Enrichment in REE observed in some samples (up to ~2000 ppm in calcite) cannot be accounted for by coupled substitutions involving Na, P or As. At Aley, the REE abundances and chondrite-normalized (La/Yb)cn ratios in carbonates decrease with progressive fractionation. Sequestration of heavy REE from carbonatitic magma by calcic garnet may be responsible for a steeply sloping "exponential" pattern and lowered Ce/Ce* ratios of calcite from Magnet Cove (USA) and other localities. Alternatively, the low levels of Ce and Mn in these samples could result from preferential removal of these elements by Ce4+- and Mn3+-bearing minerals (such as cerianite and spinels) at increasing f(O2) in the magma. The distribution of large-ion lithophile elements (LILE = Sr, Ba and Pb) in rock-forming carbonates also shows trends indicative of crystal fractionation effects (e.g., concomitant depletion in Ba + Pb at Aley, or Sr + Ba at Kerimasi), although the phases responsible for these variations cannot be identified unambiguously at present. Overall, element ratios sensitive to the redox state of the magma and its complexing characteristics (Eu/Eu*, Ce/Ce* and Y/Ho) are least variable and in both primary calcite and dolomite, approach the average chondritic values. In consanguineous rocks, calcite invariably has higher REE and LILE levels than dolomite. Hydrothermal reworking of carbonatites does not produce a unique geochemical fingerprint, leading instead to a variety of evolutionary trends that range from light-REE and LILE enrichment (Turiy Mys, Russia) to heavy-REE enrichment and LILE depletion (Bear Lodge, USA). These differences clearly attest to variations in the chemistry of carbonatitic fluids and, consequently, their ability to mobilize specific trace elements from earlier-crystallized minerals. An important telltale indicator of hydrothermal reworking is deviation from the primary, chondrite-like REE ratios (in particular, Y/Ho and Eu/Eu*), accompanied by a variety of other compositional changes depending on the redox state of the fluid (e.g., depletion of carbonates in Mn owing to its oxidation and sequestration by secondary oxides). The effect of supergene processes was studied on a single sample from Bear Lodge, which shows extreme depletion in Mn and Ce (both due to oxidation), coupled with enrichment in Pb and U, possibly reflecting an increased availability of Pb2+ and (UO2)2+ species in the system. On the basis of these findings, several avenues for future research can be outlined: (1) structural mechanisms of REE uptake by carbonates; (2) partitioning of REE and LILE between cogenetic calcite and dolomite; (3) the effects of fluorapatite, phlogopite and pyrochlore fractionation on the LILE budget of magmatic carbonates; (4) the cause(s) of coupled Mn-Ce depletion in some primary calcite; and (5) relations between fluid chemistry and compositional changes in hydrothermal carbonates.

Spinifex-textured komatiites in the south border of the Carajas ridge, Selva Greenstone belt, Carajás Province, Brazil

NASA Astrophysics Data System (ADS)

Siepierski, Lincoln; Ferreira Filho, Cesar Fonseca

2016-03-01

Spinifex-textured komatiites in the Selva greenstone belt are the first unequivocal examples of komatiites in the Transition Subdomain of the Carajás Mineral Province. Outcrops of spinifex-textured komatiites, located ∼1.5 km to the south of the Carajás ridge, were discovered during regional exploration for Ni-Cu-(PGE) sulfide deposits by VALE. They are associated with a 3.8 km long unit consisting of variable types of ultramafic rocks (talc schist, serpentinite and spinifex-textured komatiite). This ultramafic unit follows the steep dipping NW-SE trending Selva greenstone belt composed mainly by quartz-chlorite schists (interpreted as metasediments) and chlorite-actinolite schists (interpreted as metabasalts). Greenschist facies metamorphic parageneses characterize all rock types in the Selva greenstone belt. The komatiitic rocks in the Selva belt comprise a sequence of flows consisting of an upper spinifex-textured layer and a lower olivine cumulate layer. Although the spinifex and cumulus textures are well preserved in the field, the primary mineralogy of the komatiites has been completely replaced by greenschist facies metamorphic minerals. Platy olivine spinifex texture, consisting of an array of roughly parallel olivine plates, and random spinifex texture, consisting of randomly oriented olivine plates, are the most common primary volcanic textures in komatiites in the Selva greenstone belt. Platy and random spinifex texture is defined by former plates of olivine replaced by serpentine with minor actinolite, chlorite and magnetite, alternating with former matrix replaced by abundant actinolite and minor chlorite, talc, serpentine, and magnetite. The domains between olivine plates in both platy and random spinifex-textured rocks contain irregular arrays of fine-grained parallel crystals, representing primary fine-grained "quench" clinopyroxene crystals replaced by actinolite. Spinifex-textured komatiites have MgO contents bracket between 22.8 and 26.9 wt.%, and cumulate textured komatiites have MgO contents up to 40.6 wt.%. When plotted vs MgO contents, most major and minor elements fall on well-defined linear trends indicating control by olivine fractionation or accumulation. Komatiites from the Selva and Seringa (located in the Rio Maria Domain) belts are Al-undepleted with Al2O3/TiO2 ratios close to 20. Results for CaO, Na2O, and REE suggest that these elements were mobile and their abundances have been modified during metasomatic alteration. REE contents in some samples are very high (up to 40 times primitive mantle values) and REE patterns vary from flat (La/YbMN ∼ 1) to highly enriched in LREE (La/YbMN up to ∼ 10). The REE mobility may be related to hydrothermal alteration associated to Cu-Au mineralization in the region. The identification of spinifex-textured komatiites close to the Carajás Basin suggests the continuation of 3.0-2.9 Ga greenstone belts of the Rio Maria Domain within the Transition Subdomain, and enlarges the area with potential to host komatiite-associated Ni-Cu-PGE deposits.

Evaluating crustal contributions to enriched shergottites from the petrology, trace elements, and Rb-Sr and Sm-Nd isotope systematics of Northwest Africa 856

NASA Astrophysics Data System (ADS)

Ferdous, J.; Brandon, A. D.; Peslier, A. H.; Pirotte, Z.

2017-08-01

The origin of the incompatible trace element (ITE) characteristics of enriched shergottites has been critical for examining two contradicting scenarios to explain how these Martian meteorites form. The first scenario is that it reflects ITE enrichment in an early-formed mantle reservoir whereas the second scenario attributes it to assimilation of ancient Martian crust (∼4-4.5 Ga) by ITE-depleted magmas. Strongly differentiated shergottite magmas may yield added constraints for determining which scenario can best explain this signature in enriched shergottites. The meteorite Northwest Africa (NWA) 856 is a basaltic shergottite that, unlike many enriched shergottites, lacks olivine and has undergone extensive differentiation from more primitive parent magma. In similarity to other basaltic shergottites, NWA 856 is comprised primarily of compositionally zoned clinopyroxenes (45% pigeonite and 23% augite), maskelynite (23%) and accessory minerals such as ulvöspinel, merrillite, Cl-apatite, ilmenite, pyrrhotite, baddeleyite and silica polymorph. The CI-chondrite normalized rare earth element (REE) abundance patterns for its maskelynite, phosphates, and its whole rock are flat with corresponding light-REE depletions in clinopyroxenes. The 87Rb-87Sr and 147Sm-143Nd internal isochron ages are 162 ± 14 (all errors are ±2σ) Ma and 162.7 ± 5.5 Ma, respectively, with an initial εNdI = -6.6 ± 0.2. The Rb-Sr isotope systematics are affected by terrestrial alteration resulting in larger scatter and a less precise internal isochron age. The whole rock composition is used in MELTS simulations to model equilibrium and fractional crystallization sequences to compare with the crystallization sequence from textural observations and to the mineral compositions. These models constrain the depth of initial crystallization to a pressure range of 0.4-0.5 GPa (equivalent to 34-42 km) in anhydrous conditions at the Fayalite-Magnetite-Quartz buffer, and consistently reproduce the observed mineralogy throughout the sequence with progressive crystallization. The Ti/Al ratios in the clinopyroxenes are consistent with initial crystallization occurring at these depths followed by polybaric crystallization as the parent magma ascended to the surface. The REE abundances in the clinopyroxenes and maskelynite are consistent with progressive crystallization in a closed system. The new results for NWA 856 are combined with other shergottite data and are compared to mixing and assimilation and fractional crystallization (AFC) models using depleted shergottite magmas and ancient Martian crust as end-members. The models indicate that the range of REE abundances and ratios, when taken in isolation, can be successfully explained for all shergottites by crustal contamination. However, no successful crustal contamination model can explain the restricted εNdI of -6.8 ± 0.2 over the wide range of Mg# (0.65-0.25), and corresponding trace element variations from enriched shergottites to depleted shergottites. The findings indicate that the origin of the long-term ITE-enriched signature in enriched shergottites and the geochemical variability seen in shergottites is not a result of crustal contamination but instead reflects ancient mantle heterogeneity.

Petrology of the Rainy Lake area, Minnesota, USA-implications for petrotectonic setting of the archean southern Wabigoon subprovince of the Canadian Shield

NASA Astrophysics Data System (ADS)

Day, Warren C.

1990-08-01

The Rainy Lake area in northern Minnesota and southwestern, Ontario is a Late Archean (2.7 Ga) granite-greenstone belt within the Wabigoon subprovince of the Canadian Shield. In Minnesota the rocks include mafic and felsic volcanic rocks, volcaniclastic, chemical sedimentary rocks, and graywacke that are intrucded by coeval gabbro, tonalite, and granodiorite. New data presented here focus on the geochemistry and petrology of the Minnesota part of the Rainy Lake area. Igneous rocks in the area are bimodal. The mafic rocks are made up of three distinct suites: (1) low-TiO2 tholeiite and gabbro that have slightly evolved Mg-numbers (63 49) and relatively flat rare-earth element (REE) patterns that range from 20 8 x chondrites (Ce/YbN=0.8 1.5); (2) high-TiO2 tholeiite with evolved Mg-numbers (46 29) and high total REE abundances that range from 70 40 x chondrites (Ce/YbN=1.8 3.3), and (3) calc-alkaline basaltic andesite and geochemically similar monzodiorite and lamprophyre with primitive Mg-numbers (79 63), enriched light rare-earth elements (LREE) and depleted heavy rare-earth elements (HREE). These three suites are not related by partial melting of a similar source or by fractional crystallization of a common parental magma; they resulted from melting of heterogeneous Archean mantle. The felsic rocks are made up of two distinct suites: (1)low-Al2O3 tholeiitic rhyolite, and (2) high-Al2O3 calc-alkaline dacite and rhyolite and consanguineous tonalite. The tholeiitic felsic rocks are high in Y, Zr, Nb, and total REE that are unfractionated and have pronounced negative Eu anomalies. The calcalkaline felsic rocks are depleted in Y, Zr, and Nb, and the REE that are highly fractionated with high LREE and depleted HREE, and display moderate negative Eu anomalies. Both suites of felsic rocks were generated by partial melting of crustal material. The most reasonable modern analog for the paleotectonic setting is an immature island arc. The bimodal volcanic rocks are intercalated with sedimentary rocks and have been intruded by pre- and syntectonic granitoid rocks. However, the geochemistry of the mafic rocks does not correlate fully with that of mafic rocks in modern are evvironments. The low-TiO2 tholeiite is similar to both N-type mid-ocean-ridge basalt (MORB) and low-K tholeiite from immature marginal basins. The calc-alkaline basaltic andesite is like that of low-K calc-alkaline mafic volcanic rocks from oceanic volcanic arcs; however, the high-TiO2 tholeiite is most similar to modern E-type MORB, which occurs in oceanic rifts. The conundrum may be explained by: (1) rifting of a pre-existing immature arc system to produce the bimodal volcanic rocks and high-TiO2 tholeiite; (2) variable enrichment of a previously depleted Archean mantle, to produce both the low- and high-TiO2 tholeiite and the calc-alkaline basaltic andesite, and/or (3) enrichment of the parental rocks of the high-TiO2 tholeiite by crustal contamination.

Petrology of the Rainy Lake area, Minnesota, USA-implications for petrotectonic setting of the archean southern Wabigoon subprovince of the Canadian Shield

USGS Publications Warehouse

Day, W.C.

1990-01-01

The Rainy Lake area in northern Minnesota and southwestern, Ontario is a Late Archean (2.7 Ga) granite-greenstone belt within the Wabigoon subprovince of the Canadian Shield. In Minnesota the rocks include mafic and felsic volcanic rocks, volcaniclastic, chemical sedimentary rocks, and graywacke that are intrucded by coeval gabbro, tonalite, and granodiorite. New data presented here focus on the geochemistry and petrology of the Minnesota part of the Rainy Lake area. Igneous rocks in the area are bimodal. The mafic rocks are made up of three distinct suites: (1) low-TiO2 tholeiite and gabbro that have slightly evolved Mg-numbers (63-49) and relatively flat rare-earth element (REE) patterns that range from 20-8 x chondrites (Ce/YbN=0.8-1.5); (2) high-TiO2 tholeiite with evolved Mg-numbers (46-29) and high total REE abundances that range from 70-40 x chondrites (Ce/YbN=1.8-3.3), and (3) calc-alkaline basaltic andesite and geochemically similar monzodiorite and lamprophyre with primitive Mg-numbers (79-63), enriched light rare-earth elements (LREE) and depleted heavy rare-earth elements (HREE). These three suites are not related by partial melting of a similar source or by fractional crystallization of a common parental magma; they resulted from melting of heterogeneous Archean mantle. The felsic rocks are made up of two distinct suites: (1)low-Al2O3 tholeiitic rhyolite, and (2) high-Al2O3 calc-alkaline dacite and rhyolite and consanguineous tonalite. The tholeiitic felsic rocks are high in Y, Zr, Nb, and total REE that are unfractionated and have pronounced negative Eu anomalies. The calcalkaline felsic rocks are depleted in Y, Zr, and Nb, and the REE that are highly fractionated with high LREE and depleted HREE, and display moderate negative Eu anomalies. Both suites of felsic rocks were generated by partial melting of crustal material. The most reasonable modern analog for the paleotectonic setting is an immature island arc. The bimodal volcanic rocks are intercalated with sedimentary rocks and have been intruded by pre- and syntectonic granitoid rocks. However, the geochemistry of the mafic rocks does not correlate fully with that of mafic rocks in modern are evvironments. The low-TiO2 tholeiite is similar to both N-type mid-ocean-ridge basalt (MORB) and low-K tholeiite from immature marginal basins. The calc-alkaline basaltic andesite is like that of low-K calc-alkaline mafic volcanic rocks from oceanic volcanic arcs; however, the high-TiO2 tholeiite is most similar to modern E-type MORB, which occurs in oceanic rifts. The conundrum may be explained by: (1) rifting of a pre-existing immature arc system to produce the bimodal volcanic rocks and high-TiO2 tholeiite; (2) variable enrichment of a previously depleted Archean mantle, to produce both the low- and high-TiO2 tholeiite and the calc-alkaline basaltic andesite, and/or (3) enrichment of the parental rocks of the high-TiO2 tholeiite by crustal contamination. ?? 1990 Springer-Verlag.

Off-line separation and determination of rare earth elements associated with chloroplast pigments of hyperaccumulator Dicranopteris dichotoma by normal-phase liquid chromatography and ICP-MS.

PubMed

Wei, Z G; Hong, F S; Yin, M; Li, H X; Hu, F; Zhao, G W; Wong, J W C

2004-10-01

An off-line normal-phase liquid chromatography-ICP-MS method has been used for separation and determination of the rare earth elements (REE) associated with chloroplast pigments of Dicranopteris dichotoma. The stability of REE-bound pigments was tested, and almost no destruction of REE-bound pigments occurred during the so-called normal-phase liquid chromatography. The accumulated free REE ions on the microcrystalline cellulose column were cleaned by elution with 5 mmol L(-1) 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (P507), to avoid exchange of these free ions with metals from the pigments. When these precautions were taken, the method was applied to the study of REE-bound pigments in D. dichotoma. ICP-MS results showed REE were present in chlorophylls and lutein, although REE concentrations in carotene and pheophytin were both below procedural blank levels. By careful analysis of the eluate fractions containing chlorophyll a it was found that REE-bound chlorophyll a in D. dichotoma was slightly enriched in the fractions with relatively short retention time. Results indicated that the retention time of REE-bound chlorophyll a might be slightly less than that of magnesium chlorophyll a, and REE-bound chlorophylls might be of relatively low polarity in comparison with magnesium bound chlorophylls. This phenomenon could be explained by the special double-decker sandwich-structure of REE-bound chlorophylls, as was reported by us and other authors. On the basis of these results we preferred to consider that REE can replace magnesium in chlorophyll a of D. dichotoma, and that the role of REE-bound chlorophylls in photosynthesis cannot be neglected. These data might be useful for understanding of both the properties of REE-bound pigments and the effect of REE on plant photosynthesis.

Effects of rare earth elements and REE-binding proteins on physiological responses in plants.

PubMed

Liu, Dongwu; Wang, Xue; Chen, Zhiwei

2012-02-01

Rare earth elements (REEs), which include 17 elements in the periodic table, share chemical properties related to a similar external electronic configuration. REEs enriched fertilizers have been used in China since the 1980s. REEs could enter the cell and cell organelles, influence plant growth, and mainly be bound with the biological macromolecules. REE-binding proteins have been found in some plants. In addition, the chlorophyll activities and photosynthetic rate can be regulated by REEs. REEs could promote the protective function of cell membrane and enhance the plant resistance capability to stress produced by environmental factors, and affect the plant physiological mechanism by regulating the Ca²⁺ level in the plant cells. The focus of present review is to describe how REEs and REE-binding proteins participate in the physiological responses in plants.

Steric hindrance and the enhanced stability of light rare-earth elements in hydrothermal fluids

USGS Publications Warehouse

Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2009-01-01

A series of X-ray absorption spectroscopy (XAS) experiments were made to determine the structure and stability of aqueous REE (La, Nd, Gd, and Yb) chloride complexes to 500 ??C and 520 MPa. The REE3+ ions exhibit inner-sphere chloroaqua complexation with a steady increase of chloride coordination with increasing temperature in the 150 to 500 ??C range. Furthermore, the degree of chloride coordination of REE3+ inner-sphere chloroaqua complexes decreases significantly from light to heavy REE. These results indicate that steric hindrance drives the reduction of chloride coordination of REE3+ inner-sphere chloroaqua complexes from light to heavy REE. This results in greater stability and preferential transport of light REE3+ over heavy REE3+ ions in saline hydrothermal fluids. Accordingly, the preferential mobility of light REE directly influences the relative abundance of REE in rocks and minerals and thus needs to be considered in geochemical modeling of petrogenetic and ore-forming processes affected by chloride-bearing hydrothermal fluids.

Rare-earth elements

USGS Publications Warehouse

Van Gosen, Bradley S.; Verplanck, Philip L.; Seal, Robert R.; Long, Keith R.; Gambogi, Joseph; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

The rare-earth elements (REEs) are 15 elements that range in atomic number from 57 (lanthanum) to 71 (lutetium); they are commonly referred to as the “lanthanides.” Yttrium (atomic number 39) is also commonly regarded as an REE because it shares chemical and physical similarities and has affinities with the lanthanides. Although REEs are not rare in terms of average crustal abundance, the concentrated deposits of REEs are limited in number.Because of their unusual physical and chemical properties, the REEs have diverse defense, energy, industrial, and military technology applications. The glass industry is the leading consumer of REE raw materials, which are used for glass polishing and as additives that provide color and special optical properties to the glass. Lanthanum-based catalysts are used in petroleum refining, and cerium-based catalysts are used in automotive catalytic converters. The use of REEs in magnets is a rapidly increasing application. Neodymium-iron-boron magnets, which are the strongest known type of magnets, are used when space and weight are restrictions. Nickel-metal hydride batteries use anodes made of a lanthanum-based alloys.China, which has led the world production of REEs for decades, accounted for more than 90 percent of global production and supply, on average, during the past decade. Citing a need to retain its limited REE resources to meet domestic requirements as well as concerns about the environmental effects of mining, China began placing restrictions on the supply of REEs in 2010 through the imposition of quotas, licenses, and taxes. As a result, the global rare-earth industry has increased its stockpiling of REEs; explored for deposits outside of China; and promoted new efforts to conserve, recycle, and substitute for REEs. New mine production began at Mount Weld in Western Australia, and numerous other exploration and development projects noted in this chapter are ongoing throughout the world.The REE-bearing minerals are diverse and often complex in composition. At least 245 individual REE-bearing minerals are recognized; they are mainly carbonates, fluorocarbonates, and hydroxylcarbonates (n = 42); oxides (n = 59); silicates (n = 85); and phosphates (n = 26).Many of the world’s significant REE deposits occur in carbonatites, which are carbonate igneous rocks. The REEs also have a strong genetic association with alkaline magmatism. The systematic geologic and chemical processes that explain these observations are not well understood. Economic or potentially economic REE deposits have been found in (a) carbonatites, (b) peralkaline igneous systems, (c) magmatic magnetite-hematite bodies, (d) iron oxide-copper-gold (IOCG) deposits, (e) xenotime-monazite accumulations in mafic gneiss, (f) ion-absorption clay deposits, and (g) monazite-xenotime-bearing placer deposits. Carbonatites have been the world’s main source for the light REEs since the 1960s. Ion-adsorption clay deposits in southern China are the world’s primary source of the heavy REEs. Monazite-bearing placer deposits were important sources of REEs before the mid-1960s and may be again in the future. In recent years, REEs have been produced from large carbonatite bodies mined at the Mountain Pass deposit in California and, in China, at the Bayan Obo deposit in Nei Mongol Autonomous Region, the Maoniuping deposit in Sichuan Province, the Daluxiang deposit in Sichuan Province, and the Weishan deposit in Anhui Province. Alkaline igneous complexes have recently been targeted for exploration because of their enrichments in the heavy REEs.Information relevant to the environmental aspects of REE mining is limited. Little is known about the aquatic toxicity of REEs. The United States lacks drinking water standards for REEs. The concentrations of REEs in environmental media are influenced by their low abundances in crustal rocks and their limited solubility in most groundwaters and surface waters. The scarcity of sulfide minerals, including pyrite, minimizes or eliminates concerns about acid-mine drainage for carbonatite-hosted deposits and alkaline-intrusion-related REE deposits. For now, insights into environmental responses of REE mine wastes must rely on predictive models.

REE Incorporation into Calcite Individual Crystals as One Time Spike Addition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gabitov, Rinat; Sadekov, Aleksey; Migdisov, Artas

Experiments on the incorporation of trace elements into calcite were performed, and rare earth elements (REE) were used to mark the growth zones of individual crystals. Experiments were conducted at different pH (7.7 to 8.8) and temperatures (2 °C to 24.6 °C) in NH 4Cl + CaCl 2 solutions, where REE were rapidly consumed by growing calcite. LA-ICP-MS line-scans yielded the distribution of (REE/Ca) calcite within individual crystals in a manner consistent with the addition of REE into fluid. A sharp decrease of (REE/Ca) calcite toward the crystal edge suggests the fast depletion of (REE/Ca) fluid due to strong REEmore » consumption by growing calcite. An attempt was made to estimate the lower limit of the partition coefficients between calcite and fluid using selected REE/Ca data within individual calcite crystals and the amount of REE added into fluid.« less

REE Incorporation into Calcite Individual Crystals as One Time Spike Addition

DOE PAGES

Gabitov, Rinat; Sadekov, Aleksey; Migdisov, Artas

2017-10-26

Experiments on the incorporation of trace elements into calcite were performed, and rare earth elements (REE) were used to mark the growth zones of individual crystals. Experiments were conducted at different pH (7.7 to 8.8) and temperatures (2 °C to 24.6 °C) in NH 4Cl + CaCl 2 solutions, where REE were rapidly consumed by growing calcite. LA-ICP-MS line-scans yielded the distribution of (REE/Ca) calcite within individual crystals in a manner consistent with the addition of REE into fluid. A sharp decrease of (REE/Ca) calcite toward the crystal edge suggests the fast depletion of (REE/Ca) fluid due to strong REEmore » consumption by growing calcite. An attempt was made to estimate the lower limit of the partition coefficients between calcite and fluid using selected REE/Ca data within individual calcite crystals and the amount of REE added into fluid.« less

A supported liquid membrane system for the selective recovery of rare earth elements from neodymium-based permanent magnets

DOE PAGES

Kim, Daejin; Powell, Lawrence; Delmau, Lætitia H.; ...

2016-04-04

We present that the rare earth elements (REEs) play a vital role in the development of green energy and high-tech industries. In order to meet the fast-growing demand and to ensure sufficient supply of the REEs, it is essential to develop an efficient REE recovery process from post-consumer REE-containing products. In this research effort, we have developed a supported liquid membrane system utilizing polymeric hollow fiber modules to extract REEs from neodymium-based magnets with neutral extractants such as tetraoctyl digylcol amide (TODGA). The effect of process variables such as REE concentration, molar concentration of acid, and membrane area on REEmore » recovery was investigated. We have demonstrated the selective extraction and recovery of REEs such as Nd, Pr, and Dy without co-extraction of non-REEs from permanent NdFeB magnets through the supported liquid membrane system. The extracted REEs were then recovered by precipitation followed by the annealing step to obtain crystalline REE powders in nearly pure form. Finally, the recovered REE oxides were characterized by X-ray diffraction, scanning electron microscope coupled with energy-dispersive X-ray spectroscopy, and inductively coupled plasma–optical emission spectroscopy.« less

Comparison of respiratory quotient and resting energy expenditure in two regimens of enteral feeding – continuous vs. intermittent in head-injured critically ill patients

PubMed Central

Maurya, Indubala; Pawar, Mridula; Garg, Rakesh; Kaur, Mohandeep; Sood, Rajesh

2011-01-01

Introduction: Measurement of respiratory quotient (RQ) and resting energy expenditure (REE) has been shown to be helpful in designing nutritional regimens. There is a paucity of the literature describing the impact of a feeding regimen on the energy expenditure patterns. Therefore, we studied the effect of continuous vs. intermittent feeding regimen in head-injured patients on mechanical ventilation on RQ and REE. Methods: After institutional ethical approval, this randomized study was conducted in 40 adult male patients with head injury requiring controlled mode of ventilation. Patients were randomly allocated into two groups. Group C: Feeds (30 kcal/kg/day) were given for 18 h/day, with night rest for 6 h. Group I: Six bolus feeds (30 kcal/kg/day) were given three hourly for 18 h with night rest for 6 h. RQ and REE were recorded every 30 min for 24 h. Blood sugar was measured 4 hourly. Other adverse effects such as feed intolerance, aspiration were noted. Results: Demographic profile and SOFA score were comparable in the two groups. Base line RQ (0.8 vs. 0.86) and REE (1527 vs. 1599 kcal/day) were comparable in both the groups (P>0.05). RQ was comparable in both groups during the study period at any time of the day (P>0.05). Base line RQ was compared with all other RQ values measured every half hour and fluctuation from the base line value was insignificant in both groups (P>0.05). REE was comparable in both the groups throughout the study period (P>0.5). Adequacy of feeding as assessed by EI/MREE was 105.7% and 105.3% in group C and group I, respectively. There was no significant difference in the blood sugar levels between the two groups (P>0.05). Conclusion: We found from our study that RQ, REE, and blood sugar remain comparable with two regimens of enteral feeding – continuous vs. intermittent in neurosurgical patients on ventilator support in a ICU setup. PMID:21804803

Comparison of respiratory quotient and resting energy expenditure in two regimens of enteral feeding - continuous vs. intermittent in head-injured critically ill patients.

PubMed

Maurya, Indubala; Pawar, Mridula; Garg, Rakesh; Kaur, Mohandeep; Sood, Rajesh

2011-04-01

Measurement of respiratory quotient (RQ) and resting energy expenditure (REE) has been shown to be helpful in designing nutritional regimens. There is a paucity of the literature describing the impact of a feeding regimen on the energy expenditure patterns. Therefore, we studied the effect of continuous vs. intermittent feeding regimen in head-injured patients on mechanical ventilation on RQ and REE. After institutional ethical approval, this randomized study was conducted in 40 adult male patients with head injury requiring controlled mode of ventilation. Patients were randomly allocated into two groups. Group C: Feeds (30 kcal/kg/day) were given for 18 h/day, with night rest for 6 h. Group I: Six bolus feeds (30 kcal/kg/day) were given three hourly for 18 h with night rest for 6 h. RQ and REE were recorded every 30 min for 24 h. Blood sugar was measured 4 hourly. Other adverse effects such as feed intolerance, aspiration were noted. Demographic profile and SOFA score were comparable in the two groups. Base line RQ (0.8 vs. 0.86) and REE (1527 vs. 1599 kcal/day) were comparable in both the groups (P>0.05). RQ was comparable in both groups during the study period at any time of the day (P>0.05). Base line RQ was compared with all other RQ values measured every half hour and fluctuation from the base line value was insignificant in both groups (P>0.05). REE was comparable in both the groups throughout the study period (P>0.5). Adequacy of feeding as assessed by EI/MREE was 105.7% and 105.3% in group C and group I, respectively. There was no significant difference in the blood sugar levels between the two groups (P>0.05). We found from our study that RQ, REE, and blood sugar remain comparable with two regimens of enteral feeding - continuous vs. intermittent in neurosurgical patients on ventilator support in a ICU setup.

REE mobility during the alteration of Carbonatite and their economic potential.

NASA Astrophysics Data System (ADS)

Marien, Christian; Dijkstra, Arjan; Wilkins, Colin

2016-04-01

The supply risk of Rare Earth Elements is an unpredictable economic factor for the future application and development of modern technology for the EU. Therefore a better understanding of REE mobilisation during hydrothermal alteration of Carbonatites is essential for a safer supply of REE in general. The hydrothermal alteration of Carbonatite within the Fen Complex (Norway) forms a fine grained red hematized rock type, called Rødbergite, which is partially enriched in REE. The variation of REE within the Rødbergite is poorly understood and problematic for any future REE exploitation from Rødbergite. A genetic model of the formation of Rødbergite will provide more information about the economic potential of Rødbergite. The gradual transformation of carbonatite to Rødbergite is not easily observable due to sparse outcrop in the Fen Complex. A fresh road cut near the Bjørndallen farm (Fen Complex) provides a unique insight to the progressive hydrothermal alteration from carbonatite to Rødbergite and is therefore crucial for a genetic model of the formation of Rødbergite. 14 Samples were taken along the profile. The mineralogical, geochemical and textural characterization of the samples using the SEM as well as major-, trace- and isotopic elemental data revealed the breakdown of the primary minerals due to the infiltration of an oxidizing fluid along grain boundaries. The primary REE-minerals in unaltered Carbonatite are REE fluorocarbonates. With the increasing alteration to Rødbergite REE fluorocarbonates are progressively replaced by hematite. In contrast, monazite - a REE-phosphate - is the dominant REE mineral species in the Rødbergite. A transitional Rødbergite sample shows apatite aggregates with a strong preferential concentration of monazite along the rim of the apatite aggregates. This observation provides strong evidence for the solution of REE in the primary rock (carbonatite) by fluids and later precipitation of REE along phosphate bearing minerals (e.g. apatite) in order to form monazite. The latest results of the mineralogical investigation on the structural control of the REE mineralization, different generations of REE minerals and the potential concentration of REE in distinct zones in the profile, will also be presented. Future work will contribute to a better understanding of the REE mineralization process and therefore help to identify economically promising areas for a potential REE exploitation within the Fen Complex.

Energy Expenditure in Critically Ill Elderly Patients: Indirect Calorimetry vs Predictive Equations.

PubMed

Segadilha, Nara L A L; Rocha, Eduardo E M; Tanaka, Lilian M S; Gomes, Karla L P; Espinoza, Rodolfo E A; Peres, Wilza A F

2017-07-01

Predictive equations (PEs) are used for estimating resting energy expenditure (REE) when the measurements obtained from indirect calorimetry (IC) are not available. This study evaluated the degree of agreement and the accuracy between the REE measured by IC (REE-IC) and REE estimated by PE (REE-PE) in mechanically ventilated elderly patients admitted to the intensive care unit (ICU). REE-IC of 97 critically ill elderly patients was compared with REE-PE by 6 PEs: Harris and Benedict (HB) multiplied by the correction factor of 1.2; European Society for Clinical Nutrition and Metabolism (ESPEN) using the minimum (ESPENmi), average (ESPENme), and maximum (ESPENma) values; Mifflin-St Jeor; Ireton-Jones (IJ); Fredrix; and Lührmann. Degree of agreement between REE-PE and REE-IC was analyzed by the interclass correlation coefficient and the Bland-Altman test. The accuracy was calculated by the percentage of male and/or female patients whose REE-PE values differ by up to ±10% in relation to REE-IC. For both sexes, there was no difference for average REE-IC in kcal/kg when the values obtained with REE-PE by corrected HB and ESPENme were compared. A high level of agreement was demonstrated by corrected HB for both sexes, with greater accuracy for women. The best accuracy in the male group was obtained with the IJ equation but with a low level of agreement. The effectiveness of PEs is limited for estimating REE of critically ill elderly patients. Nonetheless, HB multiplied by a correction factor of 1.2 can be used until a specific PE for this group of patients is developed.

Towards the challenging REE exploration in Indonesia

NASA Astrophysics Data System (ADS)

Setiawan, Iwan

2018-02-01

Rare earth elements (REE) are the seventeen elements, including fifteen from 57La to 71Lu, in addition to 21Sc and 39Y. In rock-forming minerals, rare earth elements typically occur in compounds as trivalent cations in carbonates, oxides, phosphates, and silicates. The REE occur in a wide range of rock types: igneous, sedimentary and metamorphic rocks. REE are one of the critical metals in the world. Their occurrences are important to supply the world needs on high technology materials. Indonesia has a lot of potential sources of REE that are mainly from residual tin mining processes in Bangka islands, which are associated with radioactive minerals e.g. monazite and xenotime. However, the REE from monazite and xenotime are difficult to extract and contain high radioactivity. Granitoids are widely distributed in Sumatra, Sulawesi, Kalimantan and Papua. They also have a very thick weathering crusts. Important REE-bearing minerals are allanite and titanite. Their low susceptibilities during weathering result an economically potential REE concentration. I-/A- type granitoids and their weathered crusts are important REE sources in Indonesia. Unfortunately, their distribution and genesis have not been deeply studied. Future REE explorations challenge are mainly of the granitoids their weathered crusts. Geochemical and mineralogical characterization of type of granitoids and their weathered crusts, the hydrothermally altered rocks, and clear REE regulation will help discover REE deposits in Indonesia.

Analytical fingerprint for tantalum ores from African deposits

NASA Astrophysics Data System (ADS)

Melcher, F.; Graupner, T.; Sitnikova, M.; Oberthür, T.; Henjes-Kunst, F.; Gäbler, E.; Rantitsch, G.

2009-04-01

Illegal mining of gold, diamonds, copper, cobalt and, in the last decade, "coltan" has fuelled ongoing armed conflicts and civil war in a number of African countries. Following the United Nations initiative to fingerprint the origin of conflict materials and to develop a traceability system, our working group is investigating "coltan" (i.e. columbite-tantalite) mineralization especially in Africa, also within the wider framework of establishing certified trading chains (CTC). Special attention is directed towards samples from the main Ta-Nb-Sn provinces in Africa: DR Congo, Rwanda, Mozambique, Ethiopia, Egypt and Namibia. The following factors are taken into consideration in a methodological approach capable of distinguishing the origin of tantalum ores and concentrates with the utmost probability: (1) Quality and composition of coltan concentrates vary considerably. (2) Mineralogical and chemical compositions of Ta-Nb ores are extremely complex due to the wide range of the columbite-tantalite solid solution series and its ability to incorporate many additional elements. (3) Coltan concentrates may contain a number of other tantalum-bearing minerals besides columbite-tantalite. In our approach, coltan concentrates are analyzed in a step-by-step mode. State-of-the-art analytical tools employed are automated scanning electron microscopy (Mineral Liberation Analysis; MLA), electron microprobe analysis (major and trace elements), laser ablation-ICP-MS (trace elements, isotopes), and TIMS (U-Pb dating). Mineral assemblages in the ore concentrates, major and trace element concentration patterns, and zoning characteristics in the different pegmatites from Africa distinctly differ from each other. Chondrite-normalized REE distribution patterns vary significantly between columbite, tantalite, and microlite, and also relative to major element compositions of columbites. Some locations are characterized by low REE concentrations, others are highly enriched. Samples with Kibaran age either show flat patterns for most tantalites, rising values from the LREE to the HREE, or trough-like patterns. Eu anomalies are strongly negative in columbite-tantalite from the Alto Ligonha Province in Mozambique, from the Namaqualand Province (Namibia, South Africa), and from Zimbabwe. Four main age populations of coltan deposits in Africa were revealed: (1) Archean (>2.5 Ga), (2) Paleoproterozoic (2.1-1.9 Ga), (3) early Neoproterozoic ("Kibaran", 1.0-0.9 Ga), and (4) late Neoproterozoic to early Paleozoic (Pan-African; ca. 0.6-0.4 Ga). Currently, we focus on the resolution of the fingerprinting system from region via ore province down to deposit scale, establishing a large and high-quality analytical data base, and developing fast-screening and low-cost methods. Analytical flow-charts and identification schemes for coltan ores will be presented at the Conference. The analytical results obtained so far indicate that a certification scheme including fingerprinting of sources of coltan ores is feasible. The methodology developed is capable to assist in the establishment of a control instrument in an envisaged certification of the production and trade chain of coltan.

Rare earth and trace element signatures for assessing an impact of rock mining and processing on the environment: Wiśniówka case study, south-central Poland.

PubMed

Migaszewski, Zdzisław M; Gałuszka, Agnieszka; Dołęgowska, Sabina

2016-12-01

A detailed hydrogeochemical study was performed in the Wiśniówka mining area (south-central Poland). This covered three acid pit bodies, historic tailings acid ponds, acid pools, and additionally two neighboring rivers. All these acid mine drainage (AMD) waters are characterized by the pH in the range of 1.7 (pools) to 3.5 (tailings ponds). The most interesting is the Podwiśniówka acid pit lake that shows a very low pH (2.2-2.5) and very high concentrations of SO 4 2- (2720-5460 mg/L), Fe (545-1140 mg/L), Al (86.2 mg/L), As (9603-24,883 μg/L), Co (1317-3458 μg/L), Cr (753-2047 μg/L), Cu (6307-18,879 μg/L), Ni (1168-3127 μg/L), and rare earth element (REE) (589-1341 μg/L). In addition, seeps that drain the Podwiśniówka mine tailings and partly aggregate piles form strong acid pools in the mining area. Along with these pools, in which As and REE contents reach 369,726 and 6288 μg/L, respectively, these waters are among the most distinctive As- and REE-rich AMD surface waters across the world. It is noteworthy that the Podwiśniówka acid pit lake and Wiśniówka Duża acid pit sump exhibit different element signatures and REE concentration patterns normalized to North American Composite Shale (NASC): the Podwiśniówka acid pit lake always shows a characteristic roof-shaped medium REE (MREE) profile with distinct enrichments in Gd, Eu, and Tb whereas the other one displays a step-shaped heavy REE (HREE) profile with positive Tb and Gd anomalies. The REE undergo fractionation during weathering and the subsequent leaching of dissolved and suspended fractions from rocks to acid water bodies where these and other elements are further fractionated by geochemical processes. This study shows that the individual REE have greater affinities for Mn, HREE for Fe and SO 4 2- , and only La and Ce for Al. This specific water geochemistry has enabled us to (i) pinpoint the location of AMD "hot spots" originated from quartzite mining and processing operations conducted by current and previous mining companies, (ii) predict the directions and effects of future strip mining for quartzites in the Wiśniówka Duża and Podwiśniówka open pits, and (iii) evaluate the potential impact of mining and processing effluents on the quality of rivers.

High REE and Y concentrations in Co-Cu-Au ores of the Blackbird district, Idaho

USGS Publications Warehouse

Slack, J.F.

2006-01-01

Analysis of 11 samples of strata-bound Co-Cu-Au ore from the Blackbird district in Idaho shows previously unknown high concentrations of rare earth elements (REE) and Y, averaging 0.53 wt percent ???REE + Y oxides. Scanning electron microscopy indicates REE and Y residence in monazite, xenotime, and allanite that form complex intergrowths with cobaltite, suggesting coeval Co and REE + Y mineralization during the Mesoproterozoic. Occurrence of high REE and Y concentrations in the Blackbird ores, together with previously documented saline-rich fluid inclusions and Cl-rich biotite, suggest that these are not volcanogenic massive sulfide or sedimentary exhalative deposits but instead are iron oxide-copper-gold (IOCG) deposits. Other strata-bound Co deposits of Proterozoic age in the North American Cordillera and elsewhere in the world may have potential for REE and Y resources. IOCG deposits with abundant light REE should also be evaluated for possible unrecognized heavy REE and Y mineralization. ?? 2006 by Economic Geology.

Origin of heavy rare earth mineralization in South China

PubMed Central

Xu, Cheng; Kynický, Jindřich; Smith, Martin P.; Kopriva, Antonin; Brtnický, Martin; Urubek, Tomas; Yang, Yueheng; Zhao, Zheng; He, Chen; Song, Wenlei

2017-01-01

Heavy rare earth elements (HREE) are dominantly mined from the weathering crusts of granites in South China. Although weathering processes occur globally, no economic HREE resources of this type have yet been found outside China. Here, we report the occurrence of unidentified REE minerals in the granites from South Chinese deposits. They contain high levels of both HREE and light REE, but are strongly depleted in Ce, implying high oxidation state. These REE minerals show higher initial Nd isotope than primary REE-rich minerals (ɛNd(t)=0.9±0.8 versus −11.5±0.5). The mineralized weathering crusts inherited REE signature of the granites, but show more Ce depletion and more overall concentration of the REE. We propose, therefore, that highly oxidized, REE-rich fluids, derived from external, isotopically depleted sources, metasomatized the granites, which resulted in Ce depletion as Ce4+ and enrichment of the remaining REE, especially the HREE, contributing to formation of a globally important REE resource. PMID:28220784

The Hydrogeochemistry of Qingshui Geothermal Field, Northeastern Taiwan.

NASA Astrophysics Data System (ADS)

Yu-Wen, Chen; Cheng-Kuo, Lin; Wayne, Lin; Yu-Te, Chang; Pei-Shan, Hsieh

2015-04-01

The Qingshui geothermal field is located at the upstream valley of Lanyang Creek, northeastern Taiwan. It is renowned as a geothermal field. The previous studies demonstrated a higher geothermal gradient, 100oC/km warmer than a normal geotherm. However, Qingshui geothermal field has not been well developed due to the higher mining costs. In the recent years, the Taiwan government has been focusing on developing alternative and renewable energy and initiated a 10 year project, Nation Energy Program. This study is part of this project In general, it is very difficult to collect deep downhole samples without considerable change of hydro- and gas- chemistry of water under high temperature and pressure. A new sampling tool, GTF Sampler, was designed by the research team, Green Energy and Environment Laboratories, Industrial Technology Research Institute. This tool can simultaneously collect high quality geothermal water and gas sample and moreover, the sampling depth can reach up to 800 meters. Accordingly, a more accurate measurements can be conducted in the laboratory. In this study, 10 geothermal samples were collected and measured. The results demonstrate that geothermal water samples are characterized with Na(K)-HCO3 water type and located at the mature water area in Giggenbach Na-K-Mg diagram. Several geothermometers, including silica and cation geothermometry, were used to estimate potential temperature in the geothermal reservoir systems. In general, the geothermoters of Na-K and Na-K-Ca obtain reservoir temperatures between 120-190oC and 130-210oC, respectively, but the silica geothermometer indicates a lower reservoir temperature between 90 and 170oC. There is no big difference among them. It is worth to note that all calculated temperatures are lower than those of in-situ downhole measurements; therefore, more detailed and advanced researches would be needed for the inconsistency. To examine the argument about igneous heat source in the previous studies, rare earth elements (REEs) were also measured in this study. The results normalized by North America Shale REEs (NASC) show a flat pattern and a distinct europium positive anomaly. It possibly indicates a chemical interaction between meteoric water and sedimentary rock, which excludes the possibility of an igneous source.

Trace-element patterns of fibrous and monocrystalline diamonds: Insights into mantle fluids

NASA Astrophysics Data System (ADS)

Rege, S.; Griffin, W. L.; Pearson, N. J.; Araujo, D.; Zedgenizov, D.; O'Reilly, S. Y.

2010-08-01

During their growth diamonds may trap micron-scale inclusions of the fluids from which they grew, and these "time capsules" provide insights into the metasomatic processes that have modified the subcontinental lithospheric mantle. LAM-ICPMS analysis of trace elements in > 500 fibrous and monocrystalline diamonds worldwide has been used to understand the nature of these fluids. Analyses of fibrous diamonds define two general types of pattern, a "fibrous-high" (FH) one with high contents of LREE, Ba and K, and a "fibrous-low" (FL) pattern characterized by depletion in LREE/MREE, Ba and K, negative anomalies in Sr and Y, and subchondritic Zr/Hf and Nb/Ta. Both types may be found in fibrous diamonds from single deposits, and in three Yakutian pipes some diamonds show abrupt transitions from inclusion-rich cores with FH patterns to clearer rims with FL patterns. Most monocrystalline diamonds show FL-type patterns, but some have patterns that resemble those of FH fibrous diamonds. Peridotitic and eclogitic monocrystalline diamonds may show either patterns with relatively flat REE, or patterns with more strongly depleted LREE. Kimberlites that contain peridotitic diamonds with "high" patterns also contain eclogitic diamonds with "high" patterns. Strong similarities in the patterns of these two groups of diamonds may suggest high fluid/rock ratios. Many diamonds of the "superdeep" paragenesis have trace-element patterns similar to those of other monocrystalline diamonds. This may be evidence that the trace-element compositions of deep-seated fluids are generally similar to those that form diamonds in the subcontinental lithospheric mantle. The element fractionations observed between the FH and FL patterns are consistent with the immiscible separation of a silicic fluid from a carbonatite-silicate fluid, leaving a residual carbonatitic fluid strongly enriched in LREE, Ba and alkalies. This model would suggest that most monocrystalline diamonds crystallized from the more silicic fraction. Comparison with studies of single fluid inclusions in fibrous diamonds suggests that the FH patterns reflect trapped inclusions of high-Mg and low-Mg carbonatitic high-density fluids. In terms of the rock-forming elements, the fluids that precipitated the rims of some fibrous diamonds (FL pattern) and most monocrystalline diamonds are broadly similar to some hydro-silicic high-density fluids found in fibrous diamonds. However, there are still significant differences between the trace-element patterns of most monocrystalline diamonds and known high-density fluids, and further research is required to understand the formation and growth of these diamonds.

Using Rare Earth Elements (REE) to determine wind-driven soil dispersal from a point source

USDA-ARS?s Scientific Manuscript database

Although erosion of soil by water is a predictably directional process, the erosion of soil by wind is determined by wind direction on an event-wise basis. The wind-driven dispersal patterns of chemical constituents including natural soil components and anthropogenic contaminants are not well under...

Chondrule heritage and thermal histories from trace element and oxygen isotope analyses of chondrules and amoeboid olivine aggregates

NASA Astrophysics Data System (ADS)

Jacquet, Emmanuel; Marrocchi, Yves

2017-12-01

We report combined oxygen isotope and mineral-scale trace element analyses of amoeboid olivine aggregates (AOA) and chondrules in ungrouped carbonaceous chondrite, Northwest Africa 5958. The trace element geochemistry of olivine in AOA, for the first time measured by LA-ICP-MS, is consistent with a condensation origin, although the shallow slope of its rare earth element (REE) pattern is yet to be physically explained. Ferromagnesian silicates in type I chondrules resemble those in other carbonaceous chondrites both geochemically and isotopically, and we find a correlation between 16O enrichment and many incompatible elements in olivine. The variation in incompatible element concentrations may relate to varying amounts of olivine crystallization during a subisothermal stage of chondrule-forming events, the duration of which may be anticorrelated with the local solid/gas ratio if this was the determinant of oxygen isotopic ratios as proposed recently. While aqueous alteration has depleted many chondrule mesostases in REE, some chondrules show recognizable subdued group II-like patterns supporting the idea that the immediate precursors of chondrules were nebular condensates.

Geochemical and multi-isotopic ( 87Sr/ 86Sr, 143Nd/ 144Nd, 238U/ 235U) perspectives of sediment sources, depositional conditions, and diagenesis of the Marcellus Shale, Appalachian Basin, USA

DOE PAGES

Phan, Thai T.; Gardiner, James B.; Capo, Rosemary C.; ...

2017-10-25

Here, we investigate sediment sources, depositional conditions and diagenetic processes affecting the Middle Devonian Marcellus Shale in the Appalachian Basin, eastern USA, a major target of natural gas exploration. Multiple proxies, including trace metal contents, rare earth elements (REE), the Sm-Nd and Rb-Sr isotope systems, and U isotopes were applied to whole rock digestions and sequentially extracted fractions of the Marcellus shale and adjacent units from two locations in the Appalachian Basin. The narrow range of εNd values (from –7.8 to –6.4 at 390 Ma) is consistent with derivation of the clastic sedimentary component of the Marcellus Shale from amore » well-mixed source of fluvial and eolian material of the Grenville orogenic belt, and indicate minimal post-depositional alteration of the Sm-Nd system. While silicate minerals host >80% of the REE in the shale, data from sequentially extracted fractions reflect post-depositional modifications at the mineralogical scale, which is not observed in whole rock REE patterns.« less

Geochemical and multi-isotopic ( 87Sr/ 86Sr, 143Nd/ 144Nd, 238U/ 235U) perspectives of sediment sources, depositional conditions, and diagenesis of the Marcellus Shale, Appalachian Basin, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phan, Thai T.; Gardiner, James B.; Capo, Rosemary C.

Here, we investigate sediment sources, depositional conditions and diagenetic processes affecting the Middle Devonian Marcellus Shale in the Appalachian Basin, eastern USA, a major target of natural gas exploration. Multiple proxies, including trace metal contents, rare earth elements (REE), the Sm-Nd and Rb-Sr isotope systems, and U isotopes were applied to whole rock digestions and sequentially extracted fractions of the Marcellus shale and adjacent units from two locations in the Appalachian Basin. The narrow range of εNd values (from –7.8 to –6.4 at 390 Ma) is consistent with derivation of the clastic sedimentary component of the Marcellus Shale from amore » well-mixed source of fluvial and eolian material of the Grenville orogenic belt, and indicate minimal post-depositional alteration of the Sm-Nd system. While silicate minerals host >80% of the REE in the shale, data from sequentially extracted fractions reflect post-depositional modifications at the mineralogical scale, which is not observed in whole rock REE patterns.« less

Sharp transition from ripple patterns to a flat surface for ion beam erosion of Si with simultaneous co-deposition of iron

NASA Astrophysics Data System (ADS)

Zhang, K.; Brötzmann, M.; Hofsäss, H.

2012-09-01

We investigate pattern formation on Si by sputter erosion under simultaneous co-deposition of Fe atoms, both at off-normal incidence, as function of the Fe surface coverage. The patterns obtained for 5 keV Xe ion irradiation at 30° incidence angle are analyzed with atomic force microscopy. Rutherford backscattering spectroscopy of the local steady state Fe content of the Fe-Si surface layer allows a quantitative correlation between pattern type and Fe coverage. With increasing Fe coverage the patterns change, starting from a flat surface at low coverage (< 2×1015 Fe/cm2) over dot patterns (2-8×1015 Fe/cm2), ripples patterns (8-17×1015 Fe/cm2), pill bug structures (1.8×1016 Fe/cm2) and a rather flat surface with randomly distributed weak pits at high Fe coverage (>1.8×1016 Fe/cm2). Our results confirm the observations by Macko et al. for 2 keV Kr ion irradiation of Si with Fe co-deposition. In particular, we also find a sharp transition from pronounced ripple patterns with large amplitude (rms roughness ˜ 18 nm) to a rather flat surface (rms roughness ˜ 0.5 nm). Within this transition regime, we also observe the formation of pill bug structures, i.e. individual small hillocks with a rippled structure on an otherwise rather flat surface. The transition occurs within a very narrow regime of the steady state Fe surface coverage between 1.7 and 1.8×1016 Fe/cm2, where the composition of the mixed Fe-Si surface layer of about 10 nm thickness reaches the stoichiometry of FeSi2. Phase separation towards amorphous iron silicide is assumed as the major contribution for the pattern formation at lower Fe coverage and the sharp transition from ripple patterns to a flat surface.

Scarcity of rare earth elements.

PubMed

de Boer, M A; Lammertsma, K

2013-11-01

Rare earth elements (REEs) are important for green and a large variety of high-tech technologies and are, therefore, in high demand. As a result, supply with REEs is likely to be disrupted (the degree of depends on the REE) in the near future. The 17 REEs are divided into heavy and light REEs. Other critical elements besides REEs, identified by the European Commission, are also becoming less easily available. Although there is no deficiency in the earth's crust of rare earth oxides, the economic accessibility is limited. The increased demand for REEs, the decreasing export from China, and geopolitical concerns on availability contributed to the (re)opening of mines in Australia and the USA and other mines are slow to follow. As a result, short supply of particularly terbium, dysprosium, praseodymium, and neodymium is expected to be problematic for at least the short term, also because they cannot be substituted. Recycling REEs from electronic waste would be a solution, but so far there are hardly any established REE recycling methods. Decreasing the dependency on REEs, for example, by identifying possible replacements or increasing their efficient use, represents another possibility. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The behavior of rare earth elements in naturally and anthropogenically acidified waters

USGS Publications Warehouse

Wood, Scott A.; Gammons, Christopher H.; Parker, Stephen R.

2006-01-01

In this paper, the behavior of rare earth elements (REE) in a watershed impacted by acid-mine drainage (Fisher Creek, Montana) is compared to that in a volcanically acidified watershed (Rio Agrio and Lake Caviahue, Argentina). The REE behave conservatively in acidic waters with pH values less than approximately 5.5. However, above pH 5.5, REE concentrations are controlled by adsorption onto or co-precipitation with a variety of Fe or Al oxyhydroxides. The heavy REE partition to a greater extent into the solid phase than the light REE as pH rises above 6. Concentrations of REE exhibit diel (24-h) cycling in waters that were initially acidic, but have become neutralized downstream. In Fisher Creek, at the most downstream sampling station investigated (pH 6.8), concentrations of dissolved REE were 190–840% higher in the early morning versus the late afternoon. This cycling can be related to temperature-dependent, cyclic adsorption–desorption of REE onto hydrous ferric or aluminum oxide or both. Similar but gentler diel cycling of the REE was found at Rio Agrio. The existence of such cycling has important ramifications for the study of REE in natural waters.

Characteristics and genesis of Rare Earth Element (REE) in western Indonesia

NASA Astrophysics Data System (ADS)

Handoko, A. D.; Sanjaya, E.

2018-02-01

Rare Earth Element (REE) has unique properties that have been used in many hightech applications. The demand of REE increased recently in the world due to its special properties. Although REE concentration in the crust is higher than gold, economically viable deposits are still rare. Reduction of REE exports by China cause increased prices of REE. Due to this condition, exploration of potential REE mines emerged. Indonesia also participates in this phenomenon, and explore the possibility of REE mines in its area. This review will discuss the characteristics and genesis of REE and its occurrence in western Indonesia; focused in Sumatera, Tin Island, and Kalimantan. The review is done based on literature research from several resources about characteristics of rare earth element in general and in the given area. The research shows that the potential REE mines can be found in several different locations in Indonesia, such as Tin Island, Sumatera, and Kalimantan. Most of them are composed of monazite, zircon, and xenotime as rare earth minerals. Monazite iss known for its elevated number of radioactive elements, so study about radioactive content and more environment friendly ore processing becomes compulsory.

Resting Energy Expenditure in Adults with Becker’s Muscular Dystrophy

PubMed Central

Jacques, Matthew F.; Orme, Paul; Smith, Jonathon; Morse, Christopher I.

2017-01-01

Purpose The purpose of this study was: 1) To compare Resting energy expenditure (REE) in adult males with Becker’s Muscular Dystrophy (BeMD, n = 21, 39 ±12 years) and healthy controls (CTRL, n = 12, 37 ±12 years) 2) Determine whether other physiological parameters correlate with REE in BeMD, and 3) Compare current prediction methods of REE with measured REE. Methods REE was calculated via indirect calorimetry using continuous, expired gas analysis following an overnight fast. Fat free mass (FFM) and fat mass were measured by bioelectrical impedance. B-mode ultrasound measured Tibialis Anterior (TA) and Gastrocnemius Medialis (GM) anatomical cross sectional area (ACSA). The Bone Specific Physical Activity Questionnaire measured physical activity. Results No difference in REE was found between CTRL and BeMD groups (1913 ±203 & 1786 ±324 Kcal respectively). Other physiological comparisons showed increased fat mass (+54%), decreased TA ACSA (-42%), increased GM ACSA (+25%) as well as reduced respiratory function (FVC -28%; FEV1−27%) in BeMD adults compared to controls. REE estimated from prediction equations (Schofield’s) in Muscular Dystrophy were different from measured REE (P<0.05, bias = -728kcal), while the Mifflin equation was no different from measured REE (r2 = 0.58, Bias = -8kcal). Within the present BeMD, REE predicted from FFM (REE = FFM x 34.57–270; r2 = 0.85) and body mass (REE = BM x 15.65 + 421.5; r2 = 0.66), were not different from measured REE (bias equals 0 and 0.2kcals, respectively) Conclusions Despite no differences in REE between CTRL and BeMD adults, increased fat masses highlights the requirement for explicit nutritional guidelines, as well as maintenance of physical activity levels, where possible. Prediction equations are frequently used in clinical settings, however these have been shown to be less accurate in BeMD; therefore, the equations proposed here should be used where possible. PMID:28060911

Sources, behaviour, and environmental and human health risks of high-technology rare earth elements as emerging contaminants.

PubMed

Gwenzi, Willis; Mangori, Lynda; Danha, Concilia; Chaukura, Nhamo; Dunjana, Nothando; Sanganyado, Edmond

2018-04-26

Recent studies show that high-technology rare earth elements (REEs) of anthropogenic origin occur in the environment including in aquatic systems, suggesting REEs are contaminants of emerging concern. However, compared to organic contaminants, there is a lack of comprehensive reviews on the anthropogenic sources, environmental behaviour, and public and ecological health risks of REEs. The current review aims to: (1) identify anthropogenic sources, transfer mechanisms, and environmental behaviour of REEs; (2) highlight the human and ecological health risks of REEs and propose mitigation measures; and (3) identify knowledge gaps and future research directions. Out of the 17 REEs, La, Gd, Ce and Eu are the most studied. The main sources of anthropogenic REE include; medical facilities, petroleum refining, mining and technology industries, fertilizers, livestock feeds, and electronic wastes and recycling plants. REEs are mobilized and transported in the environment by hydrological and wind-driven processes. Ecotoxicological effects include reduced plant growth, function and nutritional quality, genotoxicity and neurotoxicity in animals, trophic bioaccumulation, chronic and acute toxicities in soil organisms. Human exposure to REEs occurs via ingestion of contaminated water and food, inhalation, and direct intake during medical administration. REEs have been detected in human hair, nails, and biofluids. In humans, REEs cause nephrogenic systemic fibrosis and severe damage to nephrological systems associated with Gd-based contrast agents, dysfunctional neurological disorder, fibrotic tissue injury, oxidative stress, pneumoconiosis, cytotoxicity, anti-testicular effects, and male sterility. Barring REEs in medical devices, epidemiological evidence directly linking REEs in the environment to human health conditions remains weak. To minimize health risks, a conceptual framework and possible mitigation measures are highlighted. Future research is needed to better understand sources, environmental behaviour, ecotoxicology, and human epidemiology. Moreover, research on REEs in developing regions, including Africa, is needed given prevailing conditions predisposing humans to health risks (e.g., untreated drinking water). Copyright © 2018 Elsevier B.V. All rights reserved.

Lateritic, supergene rare earth element (REE) deposits

USGS Publications Warehouse

Cocker, Mark D.

2014-01-01

Intensive lateritic weathering of bedrock under tropical or sub-tropical climatic conditions can form a variety of secondary, supergene-type deposits. These secondary deposits may range in composition from aluminous bauxites to iron and niobium, and include rare earth elements (REE). Over 250 lateritic deposits of REE are currently known and many have been important sources of REE. In southeastern China, lateritic REE deposits, known as ion-adsorption type deposits, have been the world’s largest source of heavy REE (HREE). The lateritized upper parts of carbonatite intrusions are being investigated for REE in South America, Africa, Asia and Australia, with the Mt. Weld deposit in Australia being brought into production in late 2012. Lateritic REE deposits may be derived from a wide range of primary host rocks, but all have similar laterite and enrichment profiles, and are probably formed under similar climatic conditions. The weathering profile commonly consists of a depleted zone, an enriched zone, and a partially weathered zone which overlie the protolith. Lateritic weathering may commonly extend to depths of 30 to 60 m. REE are mobilized from the breakdown of primary REE-bearing minerals and redeposited in the enriched zone deeper in the weathering horizon as secondary minerals, as colloids, or adsorbed on other secondary minerals. Enrichment of REE may range from 3 to 10 times that of the source lithology; in some instances, enrichment may range up to 100 times.

Validity of Predictive Equations for Resting Energy Expenditure Developed for Obese Patients: Impact of Body Composition Method

PubMed Central

Achamrah, Najate; Jésus, Pierre; Grigioni, Sébastien; Rimbert, Agnès; Petit, André; Déchelotte, Pierre; Folope, Vanessa; Coëffier, Moïse

2018-01-01

Predictive equations have been specifically developed for obese patients to estimate resting energy expenditure (REE). Body composition (BC) assessment is needed for some of these equations. We assessed the impact of BC methods on the accuracy of specific predictive equations developed in obese patients. REE was measured (mREE) by indirect calorimetry and BC assessed by bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA). mREE, percentages of prediction accuracy (±10% of mREE) were compared. Predictive equations were studied in 2588 obese patients. Mean mREE was 1788 ± 6.3 kcal/24 h. Only the Müller (BIA) and Harris & Benedict (HB) equations provided REE with no difference from mREE. The Huang, Müller, Horie-Waitzberg, and HB formulas provided a higher accurate prediction (>60% of cases). The use of BIA provided better predictions of REE than DXA for the Huang and Müller equations. Inversely, the Horie-Waitzberg and Lazzer formulas provided a higher accuracy using DXA. Accuracy decreased when applied to patients with BMI ≥ 40, except for the Horie-Waitzberg and Lazzer (DXA) formulas. Müller equations based on BIA provided a marked improvement of REE prediction accuracy than equations not based on BC. The interest of BC to improve REE predictive equations accuracy in obese patients should be confirmed. PMID:29320432

Submarine groundwater discharge is an important source of REEs to the coastal ocean

NASA Astrophysics Data System (ADS)

Johannesson, K. H.; Chevis, D. A.; Palmore, C. D.; Telfeyan, K.; Burdige, D.; Cable, J. E.; Hemming, S. R.; Rasbury, T.; Moran, S. B.; Prouty, N.; Swarzenski, P. W.

2014-12-01

Rare earth element (REE) concentrations of submarine groundwater discharge (SGD) were measured in three subterranean estuaries (i.e., Indian River Lagoon, Florida; Pettaquamscutt estuary, Rhode Island; Kona Coast, Hawaii). Using site-specific SGD estimates previously obtained by a variety of techniques (e.g., seepage meters, Ra, and Rn), we estimated SGD-derived fluxes of REEs to the coastal ocean using simple, one-dimensional modeling techniques. Our results indicate that the SGD fluxes of REEs are either of the same magnitude as riverine REE fluxes (Indian River Lagoon; Pettaquamscutt estuary), or far exceed surface runoff sources of REEs to the coastal ocean (Kona Coast). At each site important biogeochemical reactions occurring in the subterranean estuary, such as redox reactions, sediment bioirrigation, mineral dissolution and re-precipitation, and salt-induced mobilization from "nano-colloids", appear to facilitate release of REEs into solution, which are then advected to the coastal ocean via SGD. Neodymium isotope analysis of SGD and aquifer sediment are consistent with sediment diagenesis and redox transformations of Fe(III) oxides/oxyhydroxides, as well as preferential weathering of REE-bearing minerals like apatite, as being important sources of REEs to coastal seawater. Our investigations demonstrate that geochemical reactions occurring in the studied subterranean estuaries represent a net source of light and middle REEs to coastal seawater, whereas the heavy REEs appear to be sequestered in the subterranean estuary sediment.

Evaluation of photomask flatness compensation for extreme ultraviolet lithography

NASA Astrophysics Data System (ADS)

Ballman, Katherine; Lee, Christopher; Zimmerman, John; Dunn, Thomas; Bean, Alexander

2016-10-01

As the semiconductor industry continues to strive towards high volume manufacturing for EUV, flatness specifications for photomasks have decreased to below 10nm for 2018 production, however the current champion masks being produced report P-V flatness values of roughly 50nm. Write compensation presents the promising opportunity to mitigate pattern placement errors through the use of geometrically adjusted target patterns which counteract the reticle's flatness induced distortions and address the differences in chucking mechanisms between e-beam write and electrostatic clamping during scan. Compensation relies on high accuracy flatness data which provides the critical topographical components of the reticle to the write tool. Any errors included in the flatness data file are translated to the pattern during the write process, which has now driven flatness measurement tools to target a 6σ reproducibility <1nm. Using data collected from a 2011 Sematech study on the Alpha Demo Tool, the proposed methodology for write compensation is validated against printed wafer results. Topographic features which lack compensation capability must then be held to stringent specifications in order to limit their contributions to the final image placement error (IPE) at wafer. By understanding the capabilities and limitations of write compensation, it is then possible to shift flatness requirements towards the "non-correctable" portion of the reticle's profile, potentially relieving polishers from having to adhere to the current single digit flatness specifications.

Fractionations of rare earth elements in plants and their conceptive model.

PubMed

Ding, ShiMing; Liang, Tao; Yan, JunCai; Zhang, ZiLi; Huang, ZeChun; Xie, YaNing

2007-02-01

Fractionations of rare earth elements (REEs) and their mechanisms in soybean were studied through application of exogenous mixed REEs under hydroponic conditions. Significant enrichment of middle REEs (MREEs) and heavy REEs (HREEs) was observed in plant roots and leaves respectively, with slight fractionation between light REEs (LREEs) and HREEs in stems. Moreover, the tetrad effect was observed in these organs. Investigations into REE speciation in roots and in the xylem sap using X-ray absorption spectroscopy (XAS) and nanometer-sized TiO2 adsorption techniques, associated with other controlled experiments, demonstrated that REE fractionations should be dominated by fixation mechanism in roots caused by cell wall absorption and phosphate precipitation, and by the combined effects of fixation mechanism and transport mechanism in aboveground parts caused by solution complexation by intrinsic organic ligands. A conceptive model was established for REE fractionations in plants based on the above studies.

Pyroxene Pallasites: A New Pallasite Grouplet

NASA Astrophysics Data System (ADS)

Boesenberg, J. S.; Prinz, M.; Weisberg, M. K.; Davis, A. M.; Clayton, R. N.; Mayeda, T. K.; Wasson, J. T.

1995-09-01

A new pallasite grouplet, the pyroxene pallasites, consisting of the meteorites Vermillion and Y8451, has been identified by petrologic, trace element, and oxygen isotopic data. Vermillion is a new 27 kg find from central Kansas with a texture that differs from main group (MG) and Eagle Station (ES) pallasites and consists of about (vol. %) 86 FeNi metal and 14 silicates. The silicates are interspersed with metal along bands up to 1.5 cm wide within the metal host. These bands contain micron to cm-sized silicates, including rounded to subrounded olivine (up to 1.5 cm), as well as orthopyroxene, chromite, and merrillite. Y8451, previously described in [1], is texturally similar to MG pallasites and consists of FeNi metal, rounded to subangular olivine (up to 1 cm), pyroxene, chromite, and merrillite. Modally, Vermillion silicates consist of (vol. %) about 93 olivine, 5 opx, 1.5 chromite, 0.5 merrillite, while Y8451 silicates consist of about 94 olivine, 4.8 opx, 1.1 cpx, and 0.1 merrillite. Vermillion olivine (Fo(sub)(87.0-88.9)) is comparable to MG pallasite olivine [2], while that of Y8451 (Fo(sub)(88.8-89.8)) is slightly more magnesian than MG [1]. Vermillion pyroxene (En(sub)(86-88.5) Wo(sub)(0.5-2.5)) typically occurs along the rims of smaller olivine grains, although larger pyroxene inclusions (up to 1 mm) of the same composition are sometimes found within olivine grains. Y8451 has two types of opx, a lower-Ca opx (En(sub)(89.1) Wo(sub)(0.6)) with 0.3 wt% CaO, and a higher-Ca opx (En(sub)(87.6-88.1) Wo(sub)(1.9-2.3)) with 1 wt% CaO; the lower-Ca opx coexists with cpx (En(sub)(51.5-51.8) Wo(sub)(43.7-44.1)). The higher-Ca opx has a smoothly fractionated REE pattern increasing from 0.3 x CI for La to 2.5 x CI for Lu, with no Eu anomaly, and does not appear to be in equilibrium with cpx, which has a fairly flat REE pattern at about 5 x CI (Fig. 1). The lower-Ca opx, however, is in equilibrium with cpx. Merrillites in Y8451 and Vermillion have relatively flat LREE (2 x CI) patterns, with HREE increasing to near 100 x CI in Lu, and do not appear to be in equilibrium with the higher-Ca opx or cpx. FeNi metal in Vermillion has a fine octahedrite texture and contains 65 micrograms/g Cr, 4.9 mg/g Co, 75 mg/g Ni, 130 micrograms/g Cu, 44 micrograms/g Ga, 13 micrograms/g As, 0.7 micrograms/g W, 1.9 micrograms/g Ir, and 1.4 micrograms/g Au. The metal is ungrouped and differs from MG or ES pallasite metal. Y8451 metal has not yet been analyzed. Oxygen isotopic compositions of olivine are similar in Vermillion (delta^(18)O=2.24, delta^(17)O=0.40, Delta^(17)O=-0.76) and Y8451 (delta^(18)O=2.26, delta^(17)O=0.41, Delta^(17)O=-0.77) and plot (Fig. 2) below the MG pallasite mass fractionation line (Delta^(17)O=-0.32). Pyroxene pallasites are clearly resolved from MG pallasites, as well as the acapulcoite-lodranite, and IAB-IIICD-winonaite groups. Conclusions: (1) Pyroxene pallasites constitute a new pallasite subgroup. (2) Application of the two-pyroxene thermometer [2] to Y8451 indicates an equilibration temperature of about 1000 degrees C. (3) The disequilibrium between silicates and phosphates is consistent with formation of merrillite by subsolidus reaction between metal and silicate where merrillite inherits the REE patterns of the olivine and orthopyroxene that probably formed as cumulates from a chondritic melt [3]. (4) The higher-Ca opx may be a xenocryst because of its disequilibrium pattern with the coexisting silicates. (5) The presence of pyroxene coexisting with olivine in pyroxene pallasites, in contrast to olivine alone in MG pallasites, may indicate a lower temperature of crystal accumulation for the pyroxene pallasites, assuming they both started from a similar chondritic melt. (6) The presence of three pallasite groups or grouplets may be indicative of three parent bodies, with only the MG pallasites related to the HED group. (7) Whatever the cause of the unusual metal-silicate relations in pallasites, this situation must have occurred in three different settings. References: [1] Yanai K. and Kojima H. (1995) Proc. NIPR Symp. Antarc. Meteorites, 8, 1-10. [2] Lindsley D. H. and Andersen D. J. (1983) Proc. LPSC 13th, in JGR, 88, A887-A906. [3] Davis A. M. and Olsen E. J. (1991) Nature, 353, 637-640.

Rapid and highly reproducible analysis of rare earth elements by multiple collector inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Baker, Joel; Waight, Tod; Ulfbeck, David

2002-10-01

A method has been developed for the rapid chemical separation and highly reproducible analysis of the rare earth elements (REE) by isotope dilution analysis by means of a multiple collector inductively coupled plasma mass spectrometer (MC-ICP-MS). This technique is superior in terms of the analytical reproducibility or rapidity of analysis compared with quadrupole ICP-MS or with thermal ionization mass spectrometric isotope dilution techniques. Samples are digested by standard hydrofluoric-nitric acid-based techniques and spiked with two mixed spikes. The bulk REE are separated from the sample on a cation exchange column, collecting the middle-heavy and light REE as two groups, which provides a middle-heavy REE cut with sufficient separation of the light from the heavier REE to render oxide interferences trivial, and a Ba-free light REE cut. The heavy (Er-Lu), middle (Eu-Gd), and light REE (La-Eu) concentrations are determined by three short (1 to 2 min) analyses with a CETAC Aridus desolvating nebulizer introduction system. Replicate digestions of international rock standards demonstrate that concentrations can be reproduced to <1%, which reflects weighing errors during digestion and aliquotting as inter-REE ratios reproduce to ≤0.2% (2 SD). Eu and Ce anomalies reproduce to <0.15%. In addition to determining the concentrations of polyisotopic REE by isotope dilution analysis, the concentration of monoisotopic Pr can be measured during the light REE isotope dilution run, by reference to Pr/Ce and Pr/Nd ratios measured in a REE standard solution. Pr concentrations determined in this way reproduce to <1%, and Pr/REE ratios reproduce to <0.4%. Ce anomalies calculated with La and Pr also reproduce to <0.15% (2 SD). The precise Ce (and Eu) anomaly measurements should allow greater use of these features in studying the recycling of materials with these anomalies into the mantle, or redox-induced effects on the REE during recycling and dehydration of oceanic lithosphere, partial melting, metamorphism, alteration, or sedimentation processes. Moreover, this technique consumes very small amounts (subnanograms) of the REE and will allow precise REE determinations to be made on much smaller samples than hitherto possible.

The Permian-Triassic granitoids in Bayan Obo, North China Craton: A geochemical and geochronological study

NASA Astrophysics Data System (ADS)

Ling, Ming-Xing; Zhang, Hong; Li, He; Liu, Yu-Long; Liu, Jian; Li, Lin-Qing; Li, Cong-Ying; Yang, Xiao-Yong; Sun, Weidong

2014-03-01

Granitoids near the Bayan Obo giant rare earth element (REE) deposit at the north margin of the North China Craton (NCC), the world's largest light REE (LREE) deposit, have been taken by some authors as the key factors that controlled the mineralization. In contrast, others proposed that the REE deposit has been partially destructed by these granitoids. Here we report systematic studies on geochronology and geochemical characteristics of granitoids of different distances from the orebodies, to investigate the genesis and their relationship to the giant Bayan Obo deposit. Granitoids studied here, including granites and quartz monzonites, are peraluminous with A/CNK = 0.99-1.11, LREE enriched and heavy REE (HREE) depleted, with variable REE concentrations (total REE = 54-330 ppm) and large negative Eu anomaly (δEu = 0.19-0.70). The REE patterns are distinct from those of ore-bearing dolomites. Some samples have slightly higher LREE concentrations, which may have been contaminated by the orebodies during intrusion. Trace elements of the granitoids are characterized by positive Pb anomaly, strong negative Ti anomaly and Nb, Ta and Sr anomalies. The granites exhibit negative Ba anomaly. The granitoids plot within the post-collision granite field in the Pearce diagram, which is consistent with the tectonic regime. The quartz monzonites and one granite have A-type granite characteristics and belong to the A2 subgroup. Zircons in these granitoids have high Th/U values, which are typical for magmatic zircons. High precision U-Pb dating for these zircons by secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) yields Permian-Triassic 206Pb/238U ages ranging from 243.2 to 293.8 Ma. The formation of the granitoids is > 55 Ma later than the latest ore forming age. The zircons have low La concentrations (0.02-12 ppm), high (Sm/La)N (0.8-685) and Ce/Ce* (1.4-80). The Ti-in-zircon temperature of the granitoids ranges from 590 to 770 °C. All these evidences suggest that the granitoids have no contribution to the formation of the Bayan Obo deposit. Granitoids that are close to the orebodies had limited interaction with it and gained some LREE-enriched characteristics during magmatisms. Nevertheless, their effects to the orebodies are subtle. All the granitoids formed in a post-collisional tectonic regime at convergent margins, which is consistent with plate subduction during the closure of the Palaeo-Asian Ocean, which started in the Neoproterozoic and lasted until the Carboniferous/Permian.

Rare earth element concentrations in geological and synthetic samples using synchrotron X-ray fluorescence analysis

USGS Publications Warehouse

Chen, J.R.; Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Rivers, M.L.; Sutton, S.R.; Cygan, G.L.; Grossman, J.N.; Reed, M.J.

1993-01-01

The concentrations of rare earth elements (REEs) in specific mineral grains from the Bayan Obo ore deposit and synthetic high-silica glass samples have been measured by synchrotron X-ray fluorescence (SXRF) analysis using excitation of the REE K lines between 33 and 63 keV. Because SXRF, a nondestructive analytical technique, has much lower minimum detection limits (MDLs) for REEs, it is an important device that extends the in situ analytical capability of electron probe microanalysis (EPMA). The distribution of trace amounts of REEs in common rock-forming minerals, as well as in REE minerals and minerals having minor quantities of REEs, can be analyzed with SXRF. Synchrotron radiation from a bending magnet and a wiggler source at the National Synchrotron Light Source, Brookhaven National Laboratory, was used to excite the REEs. MDLs of 6 ppm (La) to 26 ppm (Lu) for 3600 s in 60-??m-thick standard samples were obtained with a 25-??m diameter wiggler beam. The MDLs for the light REEs were a factor of 10-20 lower than the MDLs obtained with a bending magnet beam. The SXRF REE concentrations in mineral grains greater than 25 ??m compared favorably with measurements using EPMA. Because EPMA offered REE MDLs as low as several hundred ppm, the comparison was limited to the abundant light REEs (La, Ce, Pr, Nd). For trace values of medium and heavy REEs, the SXRF concentrations were in good agreement with measurements using instrumental neutron activation analysis (INAA), a bulk analysis technique. ?? 1993.

Bioadsorption of Rare Earth Elements through Cell Surface Display of Lanthanide Binding Tags.

PubMed

Park, Dan M; Reed, David W; Yung, Mimi C; Eslamimanesh, Ali; Lencka, Malgorzata M; Anderko, Andrzej; Fujita, Yoshiko; Riman, Richard E; Navrotsky, Alexandra; Jiao, Yongqin

2016-03-01

With the increasing demand for rare earth elements (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium Caulobacter crescentus for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb(3+) could be effectively recovered using citrate, consistent with thermodynamic speciation calculations that predicted strong complexation of Tb(3+) by citrate. No reduction in Tb(3+) adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare earth mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation.

Bioadsorption of rare earth elements through cell surface display of lanthanide binding tags

DOE PAGES

Park, Dan M.; Reed, David W.; Yung, Mimi C.; ...

2016-02-02

In this study, with the increasing demand for rare earth elements (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium Caulobacter crescentus for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb 3+ could be effectively recovered usingmore » citrate, consistent with thermodynamic speciation calculations that predicted strong complexation of Tb 3+ by citrate. No reduction in Tb 3+ adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare earth mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation.« less

Do manganese nodules grow or dissolve after burial? Results from the Central Indian Ocean Basin

NASA Astrophysics Data System (ADS)

Pattan, J. N.; Parthiban, G.

2007-07-01

Fifty buried manganese nodules at different depth intervals were recovered in 12 sediment cores from the Central Indian Ocean Basin (CIOB). A maximum of 15 buried nodules were encountered in one sediment core (AAS-22/GC-07) and the deepest nodule was recovered at 5.50 m below seafloor in core AAS-04/GC-5A. Approximately 80% of the buried nodules are small in size (˜2 cm diameter) in contrast to the Atlantic Ocean and Peru Basin (Pacific Ocean) where the majority of the buried nodules are large, ˜8 cm and >6 cm, respectively. Buried nodule size decreases with core depth and this distribution appears to be similar to the phenomenon of "Brazil Nut Effect". Buried nodules exhibit both smooth and rough surface textures and are ellipsoidal, elongated, rounded, sub rounded, irregular and polynucleated. Buried nodules from siliceous ooze are enriched in Mn, Cu, Ni, Zn, Mo, Ga, V and Rb whereas those from red clay are enriched in Fe, Co, Ti, U, Th, Y, Cr, Nb and Rare Earth Elements (REE). Buried nodules from siliceous ooze suggest their formation under hydrogenetic, early digenetic and diagenetic processes whereas those from red clay are of hydrogenetic origin. REE are enriched more than 1.5 times in buried nodules from red clay compared to siliceous ooze. However, the mode of incorporation of REE into buried nodules from both sedimentary environments is by a single authigenic phase consisting of Fe-Ti-P. Shale-normalized REE patterns and Ce anomalies suggest that nodules from siliceous ooze formed under more oxidizing conditions than those from red clay. Nodules buried at depths between 1.5 and 2.5 m are diagenetic (Mn/Fe ratio 10-15), formed in highly oxic environments (large positive Ce anomalies) and record aeolian dust (high Eu anomalies). Chemical composition, surface texture and morphology of buried nodules are similar to those of surface nodules from the same basin. Furthermore, buried nodule compositions do not exhibit any distinct patterns within the core depth, suggesting that buried nodules neither grow nor dissolve after their burial in the sediment column.

Direct dating and characterization of the Pope's Hill REE Deposit, Labrador

NASA Astrophysics Data System (ADS)

Chafe, A. N.; Hanchar, J. M.; Fisher, C.; Piccoli, P. M.; Crowley, J. L.; Dimmell, P. M.

2012-12-01

The Pope's Hill rare earth element (REE) trend (PHT) is located approximately 100 km southwest of Happy Valley-Goose Bay, along the Trans Labrador Highway, in central Labrador. Whole-rock geochemical analyses of the main REE-bearing unit indicate total rare earth element contents ranging from 1 to 22 weight percent (wt%) REE3+. The REE-enriched unit is hosted within a hydrothermally altered syenite, trending northeast and traceable for approximately 2.8km. Samples of ore, host rock, and country rock, were collected from throughout the trend in order to: 1) quantify which phases concentrate the REE and their abundances and distribution in the ore; and 2) use in situ LA-ICPMS and ID-TIMS U-Pb geochronology and in situ Sm-Nd isotopes using LA-MC-ICPMS in monazite from the ore and host rock to constrain the timing of mineralization and determine the source of the REE. These data will help develop predictive models for this type of mineral deposit elsewhere. The PHT is defined as the host syenite and REE-enriched segregations; two contrasting lithologies. The rare earth element minerals (REE) occur in millimeter- to centimeter-scale pods that are locally discontinuous. The REE are hosted in a variety of silicate, phosphate, carbonate, and niobate phases; with a majority hosted in allanite(-Ce), titanite(-Ce), monazite(-Ce), britholite(-Ce); and a minor percentage in REE-carbonates and fergusonite(-Nd). Both apatite and titanite occur in two different compositional forms that range in chemistry from end-member stoichiometric apatite and titanite to highly REE-enriched - apatite-britholite and titanite(-Ce), where chemical substitutions, such as Si4+ + REE3+ substitute for Ca2+ + P5+ in apatite and REE3+ + Fe3+ substitute for Ca2+ + Ti4+ in titanite in order to incorporate up to ~40 wt% REE2O3 in both minerals. The U-Pb geochronology indicate that allanite, titanite(-Ce), monazite and fergusonite crystallized from ~1060 to ~940 Ma, a period spanning ~120 Ma. Sm-Nd tracer isotope data from the same minerals indicate that the syenite and ore have initial Nd within a single ɛNd unit. This combined with their field relationship to the foliation and the microtextures observed in thin section suggests that the REE minerals experienced syndeformational growth from a hydrothermal fluid, acting on both host and ore, where REEs in aqueous hard ligand complexes became saturated in silicate, phosphate, carbonate, and niobate minerals through the changing T, P and chemical conditions brought on by deformation.

Rare earth element deposits in China

USGS Publications Warehouse

Xie, Yu-Ling; Hou, Zeng-qian; Goldfarb, Richard J.; Guo, Xiang; Wang, Lei

2016-01-01

China is the world’s leading rare earth element (REE) producer and hosts a variety of deposit types. Carbonatite- related REE deposits, the most significant deposit type, include two giant deposits presently being mined in China, Bayan Obo and Maoniuping, the first and third largest deposits of this type in the world, respectively. The carbonatite-related deposits host the majority of China’s REE resource and are the primary supplier of the world’s light REE. The REE-bearing clay deposits, or ion adsorption-type deposits, are second in importance and are the main source in China for heavy REE resources. Other REE resources include those within monazite or xenotime placers, beach placers, alkaline granites, pegmatites, and hydrothermal veins, as well as some additional deposit types in which REE are recovered as by-products. Carbonatite-related REE deposits in China occur along craton margins, both in rifts (e.g., Bayan Obo) and in reactivated transpressional margins (e.g., Maoniuping). They comprise those along the northern, eastern, and southern margins of the North China block, and along the western margin of the Yangtze block. Major structural features along the craton margins provide first-order controls for REE-related Proterozoic to Cenozoic carbonatite alkaline complexes; these are emplaced in continental margin rifts or strike-slip faults. The ion adsorption-type REE deposits, mainly situated in the South China block, are genetically linked to the weathering of granite and, less commonly, volcanic rocks and lamprophyres. Indosinian (early Mesozoic) and Yanshanian (late Mesozoic) granites are the most important parent rocks for these REE deposits, although Caledonian (early Paleozoic) granites are also of local importance. The primary REE enrichment is hosted in various mineral phases in the igneous rocks and, during the weathering process, the REE are released and adsorbed by clay minerals in the weathering profile. Currently, these REE-rich clays are primarily mined from open-pit operations in southern China. The complex geologic evolution of China’s Precambrian blocks, particularly the long-term subduction of ocean crust below the North and South China blocks, enabled recycling of REE-rich pelagic sediments into mantle lithosphere. This resulted in the REE-enriched nature of the mantle below the Precambrian cratons, which were reactivated and thus essentially decratonized during various tectonic episodes throughout the Proterozoic and Phanerozoic. Deep fault zones within and along the edges of the blocks, including continental rifts and strike-slip faults, provided pathways for upwelling of mantle material.

REE speciation in low-temperature acidic waters and the competitive effects of aluminum

USGS Publications Warehouse

Gimeno, Serrano M.J.; Auque, Sanz L.F.; Nordstrom, D. Kirk

2000-01-01

The effect of simultaneous competitive speciation of dissolved rare earth elements (REEs) in acidic waters (pH 3.3 to 5.2) has been evaluated by applying the PHREEQE code to the speciation of water analyses from Spain, Brazil, USA, and Canada. The main ions that might affect REE are Al3+, F-, SO42-, and PO43-. Fluoride, normally a significant complexer of REEs, is strongly associated with Al3+ in acid waters and consequently has little influence on REEs. The inclusion of aluminum concentrations in speciation calculations for acidic waters is essential for reliable speciation of REEs. Phosphate concentrations are too low (10-4 to 10-7 m) to affect REE speciation. Consequently, SO42- is the only important complexing ligand for REEs under these conditions. According to Millero [Millero, F.J., 1992. Stability constants for the formation of rare earth inorganic complexes as a function of ionic strength. Geochim. Cosmochim. Acta, 56, 3123-3132], the lanthanide sulfate stability constants are nearly constant with increasing atomic number so that no REE fractionation would be anticipated from aqueous complexation in acidic waters. Hence, REE enrichments or depletions must arise from mass transfer reactions. (C) 2000 Elsevier Science B.V. All rights reserved.

How lithology and climate affect REE mobility and fractionation along a shale weathering transect of the Susquehanna Shale Hills Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Ma, L.; Jin, L.; Dere, A. L.; White, T.; Mathur, R.; Brantley, S. L.

2012-12-01

Shale weathering is an important process in global elemental cycles. Accompanied by the transformation of bedrock into regolith, many elements including rare earth elements (REE) are mobilized primarily by chemical weathering in the Critical Zone. Then, REE are subsequently transported from the vadose zone to streams, with eventual deposition in the oceans. REE have been identified as crucial and strategic natural resources; and discovery of new REE deposits will be facilitated by understanding global REE cycles. At present, the mechanisms and environmental factors controlling release, transport, and deposition of REE - the sources and sinks - at Earth's surface remain unclear. Here, we present a systematic study of soils, stream sediments, stream waters, soil water and bedrock in six small watersheds that are developed on shale bedrock in the eastern USA to constrain the mobility and fractionation of REE during early stages of chemical weathering. The selected watersheds are part of the shale transect established by the Susquehanna Shale Hills Observatory (SSHO) and are well suited to investigate weathering on shales of different compositions or within different climate regimes but on the same shale unit. Our REE study from SSHO, a small gray shale watershed in central Pennsylvania, shows that up to 65% of the REE (relative to parent bedrock) is depleted in the acidic and organic-rich soils due to chemical leaching. Both weathering soil profiles and natural waters show a preferential removal of middle REE (MREE: Sm to Dy) relative to light REE (La to Nd) and heavy REE (Ho to Lu) during shale weathering, due to preferential release of MREE from a phosphate phase (rhabdophane). Strong positive Ce anomalies observed in the regolith and stream sediments point to the fractionation and preferential precipitation of Ce as compared to other REE, in the generally oxidizing conditions of the surface environments. One watershed developed on the Marcellus black shale in Pennsylvania allows comparison of behaviors of REE in the organic-rich vs. organic-poor end members under the same climate conditions. Our study shows that black shale bedrock has much higher REE contents compared to the Rose Hill gray shale. The presence of reactive phases such as organic matter, carbonates and sulfides in black shale and their alteration greatly enhance the release of REE and other metals to surface environments. This observation suggests that weathering of black shale is thus of particular importance in the global REE cycles, in addition to other heavy metals that impact the health of terrestrial and aquatic ecosystems. Finally, our ongoing investigation of four more gray shale watersheds in Virginia, Tennessee, Alabama, and Puerto Rico will allow for a comparison of shale weathering along a climosequence. Such a systematic study will evaluate the control of air temperature and precipitation on REE release from gray shale weathering in eastern USA.

Correlation of nasopharyngeal carcinoma with rare earth elements and the Epstein-Barr virus.

PubMed

Zhang, Xiangmin; Zeng, Xiangfu; Liu, Lianbin; Lan, Xiaolin; Huang, Jing; Zeng, Hongxue; Li, Rong; Luo, Keqing; Wu, Wei; Zhou, Maohua; Li, Shaojin

2018-04-01

The concentration and distribution of rare earth elements (REE) in nasopharyngeal carcinoma (NPC) were measured to investigate connections with tumor size, lymph node metastasis, clinical stages, and Epstein-Barr virus (EBV) infection. There were 30 patients with NPC who met the criteria for inclusion in the present study. The EBV copy number, as well as the concentration and distribution of REE, was analyzed. EBV was detected using reverse transcription-polymerase chain reaction, with the concentrations of REE in NPC tissues measured using inductively coupled plasma-tandem mass spectrometry. The mean values were used when comparing concentrations of REE in NPC tissues as the standard deviation of this parameter was the lowest. Light REE had the highest concentrations, followed by medium, and then heavy REE. The concentrations of REE decreased with increasing tumor size and with the presence of lymph node metastasis. The concentrations of REE gradually increased between stage II and IVa, but markedly decreased thereafter. The elements that exhibited the greatest decreases were terbium, holmium and ytterbium. Furthermore, the concentrations of REE in NPC were not associated with sex (r=0.301, P=0.106) or age (r=-0.011, P=0.955), and were negatively associated with EBV (r=-0.744, P<0.001). By contrast, the EBV copy number increased alongside advancements in clinical stage. Changes in the concentrations of REE in NPC were more prominent for medium and heavy elements. Additionally, alterations in the concentrations of heavy REE may affect the occurrence and development of NPC.

Modelling of Folding Patterns in Flat Membranes and Cylinders by Origami

NASA Astrophysics Data System (ADS)

Nojima, Taketoshi

This paper describes folding methods of thin flat sheets as well as cylindrical shells by modelling folding patterns through Japanese traditional Origami technique. New folding patterns have been devised in thin flat squared or circular membrane by modifying so called Miura-Ori in Japan (one node with 4 folding lines). Some folding patterns in cylindrical shells have newly been developed including spiral configurations. Devised foldable cylindrical shells were made by using polymer sheets, and it has been assured that they can be folded quite well. The devised models will make it possible to construct foldable/deployable space structures as well as to manufacture foldable industrial products and living goods, e. g., bottles for soft drinks.

Morphologies of femtosecond laser ablation of ITO thin films using gaussian or quasi-flat top beams for OLED repair

NASA Astrophysics Data System (ADS)

Kim, Hoon-Young; Choi, Won-Suk; Ji, Suk-Young; Shin, Young-Gwan; Jeon, Jin-Woo; Ahn, Sanghoon; Cho, Sung-Hak

2018-02-01

This study compares the ablation morphologies obtained with a femtosecond laser of both Gaussian and quasi-flat top beam profiles when applied to indium tin oxide (ITO) thin films for the purpose of OLED repair. A femtosecond laser system with a wavelength of 1030 nm and pulse duration of 190 fs is used to pattern an ITO thin film. The laser fluence is optimized for patterning at 1.38 J/cm2. The patterned ITO thin film is then evaluated through both optical microscope and atomic force microscope. Ablations with a square quasi-flat top beam are demonstrated using slits with varying x- y axes. With the Gaussian beam, the pattern width of the ablated area is shown to range from 9.17 to 9.99 μm when the number of irradiation pulse increases from one to six. In contrast, when slit control is used to obtain a quasi-flat top beam, the ablated pattern width remains constant at 10 μm, despite the increase in the number of pulse. The improved surface roughness is correlated with the quasi-flat top beam through measured Ra values. Furthermore, when using the Gaussian beam, the minimum resolution of the controllable ablation depth on the ITO thin film is found to be 60 nm. In contrast, when the quasi-flat top beam is used, the minimum ablation depth decreases to 40 nm.

Trends in the Rare Earth Element Content of U.S.-Based Coal Combustion Fly Ashes.

PubMed

Taggart, Ross K; Hower, James C; Dwyer, Gary S; Hsu-Kim, Heileen

2016-06-07

Rare earth elements (REEs) are critical and strategic materials in the defense, energy, electronics, and automotive industries. The reclamation of REEs from coal combustion fly ash has been proposed as a way to supplement REE mining. However, the typical REE contents in coal fly ash, particularly in the United States, have not been comprehensively documented or compared among the major types of coal feedstocks that determine fly ash composition. The objective of this study was to characterize a broad selection of U.S. fly ashes of varied geological origin in order to rank their potential for REE recovery. The total and nitric acid-extractable REE content for more than 100 ash samples were correlated with characteristics such as the major element content and coal basin to elucidate trends in REE enrichment. Average total REE content (defined as the sum of the lanthanides, yttrium, and scandium) for ashes derived from Appalachian sources was 591 mg kg(-1) and significantly greater than in ashes from Illinois and Powder River basin coals (403 and 337 mg kg(-1), respectively). The fraction of critical REEs (Nd, Eu, Tb, Dy, Y, and Er) in the fly ashes was 34-38% of the total and considerably higher than in conventional ores (typically less than 15%). Powder River Basin ashes had the highest extractable REE content, with 70% of the total REE recovered by heated nitric acid digestion. This is likely due to the higher calcium content of Powder River Basin ashes, which enhances their solubility in nitric acid. Sc, Nd, and Dy were the major contributors to the total REE value in fly ash, based on their contents and recent market prices. Overall, this study shows that coal fly ash production could provide a substantial domestic supply of REEs, but the feasibility of recovery depends on the development of extraction technologies that could be tailored to the major mineral content and origins of the feed coal for the ash.

Effect of low doses of dietary rare earth elements on growth performance of broilers.

PubMed

He, M L; Wehr, U; Rambeck, W A

2010-02-01

The present study was designed to investigate effect of dietary rare earth elements (REE), including both organic and inorganic compounds, on growth performance of broilers. In experiment 1, a total of 180 male Ross broiler chicks were allocated to 72 pens with different assignment: four chicks per pen or individually. The following three treatment diets were applied: control, REE-chlorides at a dose of 40 mg/kg and REE-citrate at a dose of 70 mg/kg. Each treatment group had 24 pens containing both assignments (12 pens each). In experiment 2, a total of 72 male 3-day-old Ross broiler chicks were separated to four groups: control, REE-chlorides at a dose of 70 mg/kg and REE-citrate at doses of 70 mg/kg and 100 mg/kg. In experiment 1, dietary REE-citrate improved body weight gain during the overall period by 5.0% (p < 0.05) while the increase with REE-chloride was not significant. In experiment 2, growth effects (p < 0.05) were only found in the period from day 21 to slaughter with all REE forms, and feed conversion ratio was improved by 3.4% (p < 0.05) with REE-citrate. No significant effects of REE were found on chill weight, percentages of breast meat, thigh weight, drumstick weight and wing weight. Concentrations of La and Ce in the liver and muscles were very low, accounting for 0.11-0.76 and 0.02-0.30 mg/kg respectively. There was weak tendency for a dose-response relationship especially in the groups supplemented with REE-chlorides. The main blood serum biochemical parameters were not significantly affected by REE in the diets. The results suggest that dietary supplementation of low doses of REE-citrates might improve growth performance of broilers without affecting carcass composition and health of the broilers.

Hydrothermal transport, deposition, and fractionation of the REE: Experimental data and thermodynamic calculations

DOE PAGES

Migdisov, Artaches; Williams-Jones, A. E.; Brugger, J.; ...

2016-06-11

For many years, our understanding of the behavior of the REE in hydrothermal systems was based on semi-empirical estimates involving extrapolation of thermodynamic data obtained at 25 °C. Since then, a substantial body of experimental data has accumulated on the stability of aqueous complexes of the REE. These data have shown that some of the predictions of Haas et al. (1995) are accurate, but others may be in error by several orders of magnitude. However, application of the data in modeling hydrothermal transport and deposition of the REE has been severely hampered by the lack of data on the thermodynamicmore » properties of even the most common REE minerals. The discrepancies between the predictions and experimental determinations of the thermodynamic properties of aqueous REE species, together with the paucity of data on the stability of REE minerals, raise serious questions about the reliability of some models that have been proposed for the hydrothermal mobility of these critical metals. In this contribution, we review a body of high-temperature experimental data collected over the past 15 years on the stability of REE aqueous species and minerals. Using this new thermodynamic dataset, we re-evaluate the mechanisms responsible for hydrothermal transport and deposition of the REE. We also discuss the mechanisms that can result in REE fractionation during their hydrothermal transport and deposition. Here, our calculations suggest that in hydrothermal solutions, the main REE transporting ligands are chloride and sulfate, whereas fluoride, carbonate, and phosphate likely play an important role as depositional ligands. In addition to crystallographic fractionation, which is based on the differing affinity of mineral structures for the REE, our models suggest that the REE can be fractionated hydrothermally due to the differences in the stability of the LREE and HREE as aqueous chloride complexes.« less

Economic assessment for recycling critical metals from hard disk drives using a comprehensive recovery process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ruby Thuy; Diaz, Luis A.; Imholte, D. Devin

Since the 2011 price spike of rare earth elements (REEs), research on permanent magnet recycling has blossomed globally to reduce future REE criticality. Hard disk drives (HDDs) have emerged as one feasible feedstock for recovering valuable REEs such as praseodymium, neodymium, and dysprosium. However, current processes for recycling e-waste only focus on certain metals due to feedstock and metal price uncertainties. In addition, some believe that recycling REEs is unprofitable. To shed some light on the economic viability of REE recycling from HDDs, this paper combines techno-economic information of a hydrometallurgical process with end-of-life HDD availability in a simulation model.more » Results showed that adding REEs to HDD recycling was profitable given current prices. As a result, recovered REEs could meet up to 5.1% rest of world (excluding China) magnet demand. Aluminum, gold, copper scrap and REEs were the primary main revenue streams from HDD recycling.« less

Economic assessment for recycling critical metals from hard disk drives using a comprehensive recovery process

DOE PAGES

Nguyen, Ruby Thuy; Diaz, Luis A.; Imholte, D. Devin; ...

2017-06-05

Since the 2011 price spike of rare earth elements (REEs), research on permanent magnet recycling has blossomed globally to reduce future REE criticality. Hard disk drives (HDDs) have emerged as one feasible feedstock for recovering valuable REEs such as praseodymium, neodymium, and dysprosium. However, current processes for recycling e-waste only focus on certain metals due to feedstock and metal price uncertainties. In addition, some believe that recycling REEs is unprofitable. To shed some light on the economic viability of REE recycling from HDDs, this paper combines techno-economic information of a hydrometallurgical process with end-of-life HDD availability in a simulation model.more » Results showed that adding REEs to HDD recycling was profitable given current prices. As a result, recovered REEs could meet up to 5.1% rest of world (excluding China) magnet demand. Aluminum, gold, copper scrap and REEs were the primary main revenue streams from HDD recycling.« less

Trace Element Characteristics of the New Shergottite LEW88516

NASA Astrophysics Data System (ADS)

Wadhwa, M.; Crozaz, G.

1992-07-01

LEW88516, a meteorite collected in Antarctica, has recently been identified as a shergottite (Mason and Satterwhite, 1991). The shergottites belong to a group of unique achondritic meteorites, the SNCs, for which Mars has been suggested as the parent body. From preliminary petrologic and geochemical studies, it appears that LEW88516 is closely related to the shergottite ALHA77005. Like ALHA77005, LEW88516 is composed of two distinct lithologies; one consists of large (mm-sized) pyroxenes poikilitically enclosing olivine crystals, and the other is represented by interstitial areas that contain small pyroxenes, olivine, maskelynite, whitlockite, and opaques (Lindstrom et al., 1992). Besides mineralogy and texture, whole rock chemical characteristics of these two shergottites also appear to be strikingly similar (Lindstrom et al., 1992; Boynton et al., 1992). We measured REE and other selected trace elements in individual mineral phases present in LEW88516, and compared the results with similar data obtained for ALHA77005 by Lundberg et al. (1990). Analyses were made on a thin section of LEW88516 with an ion microprobe; trace elements concentrations were measured in poikilitic and interstitial pyroxenes (augites and pigeonites), maskelynite, whitlockite, and glass. The total REE inventory of LEW88516 is dominated by whitlockite, although this mineral, as in ALHA77005, is present in only small modal abundance. Maskelynite in LEW88516 is characterized by a positive Eu anomaly that is approximately twice as large as that present in the maskelynite in ALHA77005, although the rest of the REE are present in lower abundances. The homogeneous, crystallite-free glass in LEW88516 is slightly enriched relative to LEW88516 bulk rock REE abundances, and has a REE pattern that is parallel to the ALHA77005 whole rock REE pattern. Pyroxenes in LEW88516 are zoned in their trace element concentrations, as are the pyroxenes in ALHA77005. Elemental abundances (e.g., REE, Y, Ti, Zr, Cr, V) for the two meteorites follow the same trends. The compositional range of the pyroxenes in LEW88516, however, appears to be smaller than that for pyroxenes in ALHA77005. The data confirm that indeed LEW88516 and ALHA77005 are petrogenetically related. As discussed in Lundberg et al. (1990) for ALHA77005, the intercumulus melt in LEW88516, once trapped in the cumulus pile, crystallized as a closed system. The question as to whether the two meteorites are paired or not cannot be resolved until the terrestrial and cosmic ray exposure ages of LEW88516 are determined. The differences in the trace element compositional ranges of the pyroxenes, as well as in the REE abundances in the other minerals (particularly maskelynite) in LEW88516 and ALHA77005 could simply be an artifact of sampling during analysis (particularly in the case of the pyroxenes) and/or heterogeneity within a sample, and therefore do not preclude that the two meteorites are paired. On the other hand, it is possible that the two meteorites represent distinct falls. In either case, it is evident that they were generated by the same/similar igneous processes on their parent body. References: Boynton W.V., Hill D.H., and Kring D.A. (1992) Lunar Planet. Sci. (abstract) 23, 147-148. Lindstrom M.M., Mittlefehldt D.W., Treiman A.H., Wentworth S.J., Gooding J.L., Monis R.V., Keller L.P., and McKay G. (1992) Lunar Planet. Sci. (abstract) 23, 783-784. Lundberg L.L., Crozaz G., and McSween H.Y., Jr. (1990) Geochim. Cosmochim. Acta. 54, 2535-2547. Mason B. and Satterwhite C. (1991) Antarctic Meteorite Newsletter 14:2, 19.

Stages of weathering mantle formation from carbonate rocks in the light of rare earth elements (REE) and Sr-Nd-Pb isotopes

NASA Astrophysics Data System (ADS)

Hissler, Christophe; Stille, Peter

2015-04-01

Weathering mantles are widespread and include lateritic, sandy and kaolinite-rich saprolites and residuals of partially dissolved rocks. These old regolith systems have a complex history of formation and may present a polycyclic evolution due to successive geological and pedogenetic processes that affected the profile. Until now, only few studies highlighted the unusual high content of associated trace elements in weathering mantles originating from carbonate rocks, which have been poorly studied, compared to those developing on magmatic bedrocks. For instance, these enrichments can be up to five times the content of the underlying carbonate rocks. However, these studies also showed that the carbonate bedrock content only partially explains the soil enrichment for all the considered major and trace elements. Up to now, neither soil, nor saprolite formation has to our knowledge been geochemically elucidated. Therefore, the aim of this study was to examine more closely the soil forming dynamics and the relationship of the chemical soil composition to potential sources. REE distribution patterns and Sr-Nd-Pb isotope ratios have been used because they are particularly well suited to identify trace element migration, to recognize origin and mixing processes and, in addition, to decipher possible anthropogenic and/or "natural" atmosphere-derived contributions to the soil. Moreover, leaching experiments have been applied to identify mobile phases in the soil system and to yield information on the stability of trace elements and especially on their behaviour in these Fe-enriched carbonate systems. All these geochemical informations indicate that the cambisol developing on such a typical weathering mantle ("terra fusca") has been formed through weathering of a condensed Bajocian limestone-marl facies. This facies shows compared to average world carbonates important trace element enrichments. Their trace element distribution patterns are similar to those of the soil suggesting their close genetic relationships. Sr-Nd-Pb isotope data allow to identify four principal components in the soil: a silicate-rich pool at close to the surface, a leachable REE enriched pool at the bottom of the soil profile, the limestone facies on which the weathering profile developed and an anthropogenic, atmosphere-derived component detected in the soil leachates of the uppermost soil horizon. The leachable phases are mainly secondary carbonate-bearing REE phases such as bastnaesite. The isotope data and trace element distribution patterns indicate that at least four geological and environmental events impacted the chemical and isotopical compositions of the soil system since the Cretaceous.

Empirically assessing the potential release of rare earth elements from black shale under simulated hydraulic fracturing conditions

DOE PAGES

Yang, Jon; Verba, Circe; Torres, Marta; ...

2018-02-01

Rare earth elements (REEs) are economically important to modern society and the rapid growth of technologies dependent on REEs has placed considerable economic pressure on their sourcing. This study addresses whether REEs could be released as a byproduct of natural gas extraction from a series of experiments that were designed to simulate hydraulic fracturing of black shale under various pressure (25 and 27.5 MPa) and temperature (50, 90, 130 °C) conditions. The dissolved REEs in the reacted fluids displayed no propensity for the REEs to be released from black shale under high pressure and temperature conditions, a result that ismore » consistent across the different types of fluids investigated. Overall, there was a net loss of REEs from the fluid. These changes in dissolved REEs were greatest at the moment the fluids first contacted the shale and before the high temperature and high pressure conditions were imposed, although the magnitude of these changes (10 -4 μg/g) were small compared to the magnitude of the total REE content present in the solid shale samples (10 2 μg/g). These results highlight the variability and complexity of hydraulic fracturing systems and indicate that REE may not serve as robust tracers for fracturing fluid-shale reactions. Additionally, the results suggest that significant quantities of REEs may not be byproducts of hydraulically fractured shales.« less

Empirically assessing the potential release of rare earth elements from black shale under simulated hydraulic fracturing conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Jon; Verba, Circe; Torres, Marta

Rare earth elements (REEs) are economically important to modern society and the rapid growth of technologies dependent on REEs has placed considerable economic pressure on their sourcing. This study addresses whether REEs could be released as a byproduct of natural gas extraction from a series of experiments that were designed to simulate hydraulic fracturing of black shale under various pressure (25 and 27.5 MPa) and temperature (50, 90, 130 °C) conditions. The dissolved REEs in the reacted fluids displayed no propensity for the REEs to be released from black shale under high pressure and temperature conditions, a result that ismore » consistent across the different types of fluids investigated. Overall, there was a net loss of REEs from the fluid. These changes in dissolved REEs were greatest at the moment the fluids first contacted the shale and before the high temperature and high pressure conditions were imposed, although the magnitude of these changes (10 -4 μg/g) were small compared to the magnitude of the total REE content present in the solid shale samples (10 2 μg/g). These results highlight the variability and complexity of hydraulic fracturing systems and indicate that REE may not serve as robust tracers for fracturing fluid-shale reactions. Additionally, the results suggest that significant quantities of REEs may not be byproducts of hydraulically fractured shales.« less

Fluid-induced Crystallization of Majoritic Garnet During Deep Continental Subduction (Western Gneiss Region, Norway)

NASA Astrophysics Data System (ADS)

Scambelluri, M.; Pettke, T.; van Roermund, H. L.

2008-12-01

In ultrahigh pressure (UHP) rocks, garnet containing pyroxene exsolutions derives from breakdown of majorite crystallized at depths > 200 km. Presence of microdiamonds in some of these rocks [1], including those of the Western Gneiss Region (WGR) of Norway [2], may suggest a fluid-bearing environment for the genesis of majorite. The WGR UHP gneisses host garnet peridotite and websterite recording uplift from extraordinary depths prior to uptake in a subducting slab [2]. These ultramafic rocks (islands of Otrøy and Bardane) derive from depleted Archean transition-zone mantle (350 km depth) upwelled and accreted to a cratonic lithosphere (M2 stage). Evidence for this are decimetric garnets (grt) preserved in Otrøy, hosting up to 20 volume% orthopyroxene (opx) and clinopyroxene (cpx) exsolved from precursor majoritic garnet (M1 stage). The pyroxene lamellae (20-30 ¥ìm thick, hundreds of ¥ìm long) [3] were exsolved under high-T, as shown by the garnet/cpx REE distribution [4]. This Archean-mid Proterozoic record is overprinted by the 425- 390 Ma Scandian continental subduction (M3 stage), forming new grt + cpx + opx + phlogopite (phl) + spinel (sp) that contain diamond-bearing micro-inclusions witnessing deep COH subduction fluids [2]. Here we document formation of new majoritic garnet in the M3 assemblage and in veins at Bardane [5]. Textural characteristics, together with the LREE and LILE enrichments of the M3 minerals, indicate that the new majorite is linked to infiltration of subduction fluids during renewed burial towards sub-lithospheric depths. It represents the deepest occurrence of fluid-related microstructures in mantle rocks. The new majoritic garnet crystallized at grain boundaries and in micro-veins at 7 Gpa and 900-1000 °C. It hosts thin pyroxene needles (5 mm thick, 100 mm long) exsolved under comparatively low-T, as indicated by the garnet/cpx REE distribution. The trace element signature of the majorite-bearing subduction assemblage is LREE- (cpx La/Yb = 220) and LILE-enriched (appreciable Li, B, Rb, Ba, Pb, U, Th in cpx and phl), to indicate addition of crustal components. The interstitial and vein M3 majoritic garnet has flat REE patterns (La 1xChondrite; La/Yb= 0.35) and lacks the LREE depletion characteristic of common grt. The px component of majorite thus allows LREE and subordinate LILE storage in this mineral, which becomes a relevant trace element repository in the deep mantle. The REE enriched signature of M3 majorite contrasts the depleted nature of M1 (+ M2) grt: this indicates the presence of two generations of majorite in these rocks and suggests the re-fertilization of initially depleted peridotite by subduction fluid at 200 km depth. Distinct generations of majoritic garnet thus survive in the same terrain, displaying distinct textures, compositions, and exsolution T. The majorite microstructures and compositions enable to discriminate between crystallization environments: hot sub- cratonic lithosphere vs. colder subduction settings. 1 Mposkos ED, Kostopoulos DK, 2001, EPSL 192, 497- 506; 2 Van Roermund HLM. et al., 2002, Geology 30, 959-962; 3 Van Roermund HLM, Drury M., 1998, Terra Nova 10, 295-301; 4 Spengler D. et al., 2006, Nature 440, 913-917; 5 Scambelluri M. et al., 2008, Geology 36, 59-62.

Rare earth elements in coastal sediments of the northern Galician shelf: Influence of geological features

NASA Astrophysics Data System (ADS)

Prego, Ricardo; Caetano, Miguel; Bernárdez, Patricia; Brito, Pedro; Ospina-Alvarez, Natalia; Vale, Carlos

2012-03-01

The Northern coast of Galicia, NW Iberian Peninsula, exhibits a variety of geological features: Ortegal allochthonous complex, Ollo-de-Sapo autochthonous domain and massifs of Bares, Barqueiro and San-Ciprian. In order to examine the influence of terrestrial lithologies on coastal sediments, 103 samples were collected in the Rias of Ortigueira, Barqueiro and Viveiro, their neighbouring shelf and the estuaries of Mera, Sor and Landro rivers. Aluminium, Fe, Sc, particulate inorganic and organic carbon and rare earth elements (REE) were determined in the <2 mm fraction. In addition, calcite, muscovite, quartz and riebeckite minerals were identified and quantified in 33 selected samples. The distributions of riebeckite and Fe reflect the influence of Ortegal complex on the coastal areas around the Cape Ortegal. The highest concentrations of ΣREE were found in fine sediments from confined inner parts of the Rias (up to 233 mg kg-1), while most of the sands contained 11-70 mg kg-1. ΣREE normalised to European Shale (ES) highlights the relative abundance of lanthanides (ΣREEN>6) near Cape Ortegal and the innermost ria zones. The ratio between light and heavy REE (L/H) showed lower values (4-11) around Cape Ortegal and the shelf while higher ratios (15-23) were detected in west of the Cape Estaca-de-Bares and in the inner Viveiro Ria due to elevated contributions of La and Ce. The L/H values normalised to ES reflects the importance of HREE in the adjacent area to Ortegal Complex (LN/HN<0.8) and the LREE (LN/HN>1.4) in the inner estuaries and west Cape Estaca-de-Bares. The highest REE individual ES normalised were measured in fine-grained sediments of the Mera and Sor estuaries. Sediments from the eastern shelf of Cape Ortegal presented enhanced ratios only for HREE. These results indicate that distribution of REE in the northern Galician region is highly depending on the neighbouring lithological pattern, contrasting with the situation found in the western Galician shelf and the Bay of Biscay. Lanthanides can, thus, provide a useful tool to follow the sediment pathway in the land-sea boundary zones, denoting continental geochemical imprint or fluvial outputs accordingly to the existing hydrological and geological conditions.

Rare earth elements and hypertension risk among housewives: A pilot study in Shanxi Province, China.

PubMed

Wang, Bin; Yan, Lailai; Huo, Wenhua; Lu, Qun; Cheng, Zixi; Zhang, Jingxu; Li, Zhiwen

2017-01-01

Studies have shown that residents living near rare earth mining areas have high concentrations of rare earth elements (REEs) in their hair. However, the adverse effects of REEs on human health have rarely been the focus of epidemiological studies. The goal of this study was to evaluate the relationship between REEs in hair and the risk of hypertension in housewives. We recruited 398 housewives in Shanxi Province, China, consisting of 163 women with hypertension (cases) and 235 healthy women without hypertension (controls). We analyzed 15 REEs (lanthanum (La), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), Yttrium (Y), cerium (Ce), praseodymium (Pr), and neodymium (Nd)) and calcium (Ca) accumulated in housewives hair over a period of two years. The results revealed that, with the exception of Eu, concentrations of the REEs in hair were higher in the cases than in the controls. The univariate odds ratios (ORs) of the 14 REEs were >1, and four of the REEs (Dy, Tm, Yb, and Y) also had adjusted ORs > 1. The increasing dose-response trends of the four REEs further indicated the potential for increased hypertension risk. Moreover, the REEs were negatively correlated with Ca content in hair. These results might suggest an antagonistic effect of REEs on Ca in the human body. It was concluded that high intake of REEs might increase the risk of hypertension among housewives. Copyright © 2016 Elsevier Ltd. All rights reserved.

Correlation of nasopharyngeal carcinoma with rare earth elements and the Epstein-Barr virus

PubMed Central

Zhang, Xiangmin; Zeng, Xiangfu; Liu, Lianbin; Lan, Xiaolin; Huang, Jing; Zeng, Hongxue; Li, Rong; Luo, Keqing; Wu, Wei; Zhou, Maohua; Li, Shaojin

2018-01-01

The concentration and distribution of rare earth elements (REE) in nasopharyngeal carcinoma (NPC) were measured to investigate connections with tumor size, lymph node metastasis, clinical stages, and Epstein-Barr virus (EBV) infection. There were 30 patients with NPC who met the criteria for inclusion in the present study. The EBV copy number, as well as the concentration and distribution of REE, was analyzed. EBV was detected using reverse transcription-polymerase chain reaction, with the concentrations of REE in NPC tissues measured using inductively coupled plasma-tandem mass spectrometry. The mean values were used when comparing concentrations of REE in NPC tissues as the standard deviation of this parameter was the lowest. Light REE had the highest concentrations, followed by medium, and then heavy REE. The concentrations of REE decreased with increasing tumor size and with the presence of lymph node metastasis. The concentrations of REE gradually increased between stage II and IVa, but markedly decreased thereafter. The elements that exhibited the greatest decreases were terbium, holmium and ytterbium. Furthermore, the concentrations of REE in NPC were not associated with sex (r=0.301, P=0.106) or age (r=−0.011, P=0.955), and were negatively associated with EBV (r=−0.744, P<0.001). By contrast, the EBV copy number increased alongside advancements in clinical stage. Changes in the concentrations of REE in NPC were more prominent for medium and heavy elements. Additionally, alterations in the concentrations of heavy REE may affect the occurrence and development of NPC. PMID:29541176

How accurate are resting energy expenditure prediction equations in obese trauma and burn patients?

PubMed

Stucky, Chee-Chee H; Moncure, Michael; Hise, Mary; Gossage, Clint M; Northrop, David

2008-01-01

While the prevalence of obesity continues to increase in our society, outdated resting energy expenditure (REE) prediction equations may overpredict energy requirements in obese patients. Accurate feeding is essential since overfeeding has been demonstrated to adversely affect outcomes. The first objective was to compare REE calculated by prediction equations to the measured REE in obese trauma and burn patients. Our hypothesis was that an equation using fat-free mass would give a more accurate prediction. The second objective was to consider the effect of a commonly used injury factor on the predicted REE. A retrospective chart review was performed on 28 patients. REE was measured using indirect calorimetry and compared with the Harris-Benedict and Cunningham equations, and an equation using type II diabetes as a factor. Statistical analyses used were paired t test, +/-95% confidence interval, and the Bland-Altman method. Measured average REE in trauma and burn patients was 21.37 +/- 5.26 and 21.81 +/- 3.35 kcal/kg/d, respectively. Harris-Benedict underpredicted REE in trauma and burn patients to the least extent, while the Cunningham equation underpredicted REE in both populations to the greatest extent. Using an injury factor of 1.2, Cunningham continued to underestimate REE in both populations, while the Harris-Benedict and Diabetic equations overpredicted REE in both populations. The measured average REE is significantly less than current guidelines. This finding suggests that a hypocaloric regimen is worth considering for ICU patients. Also, if an injury factor of 1.2 is incorporated in certain equations, patients may be given too many calories.

Hypermetabolism is a deleterious prognostic factor in patients with amyotrophic lateral sclerosis.

PubMed

Jésus, P; Fayemendy, P; Nicol, M; Lautrette, G; Sourisseau, H; Preux, P-M; Desport, J-C; Marin, B; Couratier, P

2018-01-01

The aim of this study was to investigate patients with amyotrophic lateral sclerosis in order to determine their nutritional, neurological and respiratory parameters, and survival according to metabolic level. Nutritional assessment included resting energy expenditure (REE) measured by indirect calorimetry [hypermetabolism if REE variation (ΔREE) > 10%] and fat mass (FM) using impedancemetry. Neurological assessment included the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised score. Survival analysis used the Kaplan-Meier method and multivariate Cox model. A total of 315 patients were analysed. Median age at diagnosis was 65.9 years and 55.2% of patients were hypermetabolic. With regard to the metabolic level (ΔREE: < 10%, 10-20% and >20%), patients with ΔREE > 20% initially had a lower FM(29.7% vs. 32.1% in those with ΔREE ≤10%; P = 0.0054). During follow-up, the median slope of Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised tended to worsen more in patients with ΔREE > 20% (-1.4 vs. -1.0 points/month in those with ΔREE ≤10%; P = 0.07). Overall median survival since diagnosis was 18.4 months. ΔREE > 20% tended to increase the risk of dying compared with ΔREE ≤10% (hazard ratio, 1.33; P = 0.055). In multivariate analysis, an increased REE:FM ratio was independently associated with death (hazard ratio, 1.005; P = 0.001). Hypermetabolism is present in more than half of patients with amyotrophic lateral sclerosis. It modifies the body composition at diagnosis, and patients with hypermetabolism >20% have a worse prognosis than those without hypermetabolism. © 2017 EAN.

Accreted fragments of the Late Cretaceous Caribbean Colombian Plateau in Ecuador

NASA Astrophysics Data System (ADS)

Mamberti, Marc; Lapierre, Henriette; Bosch, Delphine; Jaillard, Etienne; Ethien, Raynald; Hernandez, Jean; Polvé, Mireille

2003-02-01

The eastern part of the Western Cordillera of Ecuador includes fragments of an Early Cretaceous (≈123 Ma) oceanic plateau accreted around 85-80 Ma (San Juan-unit). West of this unit and in fault contact with it, another oceanic plateau sequence (Guaranda unit) is marked by the occurrence of picrites, ankaramites, basalts, dolerites and shallow level gabbros. A comparable unit is also exposed in northwestern coastal Ecuador (Pedernales unit). Picrites have LREE-depleted patterns, high ɛNd i and very low Pb isotopic ratios, suggesting that they were derived from an extremely depleted source. In contrast, the ankaramites and Mg-rich basalts are LREE-enriched and have radiogenic Pb isotopic compositions similar to the Galápagos HIMU component; their ɛNd i are slightly lower than those of the picrites. Basalts, dolerites and gabbros differ from the picrites and ankaramites by flat rare earth element (REE) patterns and lower ɛNd; their Pb isotopic compositions are intermediate between those of the picrites and ankaramites. The ankaramites, Mg-rich basalts, and picrites differ from the lavas from the San Juan-Multitud Unit by higher Pb ratios and lower ɛNd i. The Ecuadorian and Gorgona 88-86 Ma picrites are geochemically similar. The Ecuadorian ankaramites and Mg-rich basalts share with the 92-86 Ma Mg-rich basalts of the Caribbean-Colombian Oceanic Plateau (CCOP) similar trace element and Nd and Pb isotopic chemistry. This suggests that the Pedernales and Guaranda units belong to the Late Cretaceous CCOP. The geochemical diversity of the Guaranda and Pedernales rocks illustrates the heterogeneity of the CCOP plume source and suggests a multi-stage model for the emplacement of these rocks. Stratigraphic and geological relations strongly suggest that the Guaranda unit was accreted in the late Maastrichtian (≈68-65 Ma).

Origin of the Permian-Triassic komatiites, northwestern Vietnam

NASA Astrophysics Data System (ADS)

Hanski, Eero; Walker, Richard J.; Huhma, Hannu; Polyakov, Gleb V.; Balykin, Pavel A.; Tran Trong Hoa; Ngo Thi Phuong

Rare examples of Phanerozoic komatiites are found in the Song Da zone, NW Vietnam. These komatiites were erupted through continental crust and may belong to the SE extension of the Permo-Triassic Emeishan volcanic province located in SW China. They provide a good opportunity to study the source characteristics of starting plume magmas in a continental flood basalt province. Erupted on late-Permian carbonate rocks, the komatiitic rocks are interbedded with low-Ti olivine basalts. Basaltic komatiites display pyroxene spinifex textures, while more magnesian rocks (MgO up to 32 wt.%) are porphyritic, containing a single, cognate population of euhedral to elongated olivine phenocrysts with Fo up to 93.0%. This suggests a highly magnesian parental magma with 22-23 wt.% MgO. In terms of major and minor elements, the komatiites are similar to the ca. 89 Ma old Gorgona Island komatiites of Colombia. The Song Da komatiites are also strongly light-rare-earth-element- (LREE) depleted (CeN/YbN 0.30-0.62) and have unfractionated heavy rare earth element (HREE) patterns. The komatiites have high Os concentrations (up to 7.0 ppb), low but variable Re/Os ratios, and define an isochron with an age of 270+/-21 Ma, and an initial 188Os/187Os ratio of 0.12506+/- 0.00041 (γOs=+0.02+/-0.40). The Os isotopic systematics of the komatiites show no effects of crustal contamination. In contrast, their initial ɛNd values range from +3 to +8, reflecting varying but generally small degrees of contamination with Proterozoic sialic basement material. Associated low-Ti basalts have low initial ɛNd values (-0.8 to -7.5), high initial γOs values (>=15), flat or LREE-enriched REE patterns, and Nb-Ta depletion. These characteristics are also attributed to variable extents of crustal contamination.

Petrology, thermobarometry and geochronology of Yelapa Complex: Implications in the tectonic history of the basement of Puerto Vallarta Batholith, Mexico

NASA Astrophysics Data System (ADS)

Gutiérrez Aguilar, F.; Schaaf, P. E. G.; Hernandez-Trevino, T.; Solis-Pichardo, G.; Vite-Sánchez, O.

2017-12-01

The Yelapa Complex (YC) is localizated in the north, central and western of Cabo Corrientes in Jalisco, México. Is constituted by metasedimentary, metaigneous and migmatites which are intruded by deformed plutons. The YC are part of the Puerto Vallarta Batholith a body of 9000 km2 exposed at the mid-western part of the Mexican Pacific margin. The para-gneis of YC in the region of Chimo, present a mineral assemblage of Sil + Bt + Pl ± Grt ± Fsp ± Ilm. The orto-gneis in the región of Cabo Corrientes are constituted by Pl + Amp ± Qz ± Ap ± Zrn. Phase equilibria modelling of two paragneis yield peak conditions of 7-8 kbar and 650-700ºC. The patterns of REE of the studied rocks suggest: 1) Enrichment of LREE and flat patterns in HREE with respect to chondrite and; 2) Negative Eu anomaly in all samples analyzed suggesting plagioclase fractionation. On the other hand, the study of individual zircons using LA-ICP-MS from 3 para-gneis and 1 orto-gneis yield following information: 1) A máximum depositional age of 223 Ma, which also show abundant zircón populations with ages between 241-273 Ma for para-gneis and 2) The protolith age crystallization of 127 Ma for orto-gneis. The results along with new Sr-Nd isotopic data from whole rock and Rb-Sr in micas, suggest a tectonic evolution for the Yelapa Complex as a transition from a passive continental margin regime ( 223-273 Ma) to a continental arc setting ( 127). Thus, regional metamorphism and multiple magmatic episodes were associated to the convergence of the Farallon and North America plates during the Middle Jurassic to the Late Cretaceous.

Watson: A new link in the IIE iron chain

NASA Technical Reports Server (NTRS)

Olsen, Edward; Davis, Andrew; Clarke, Roy S., Jr.; Schultz, Ludolf; Weber, Hartwig W.; Clayton, Robert; Mayeda, Toshiko; Jarosewich, Eugene; Sylvester, Paul; Grossman, Lawrence

1994-01-01

Watson, which was found in 1972 in South Australia, contains the largest single silicate rock mass seen in any known iron meteorite. A comprehensive study has been completed on this unusual meteorite: petrography, metallography, analyses of the silicate inclusion (whole rock chemical analysis, INAA, RNAA, noble gases, and oxygen isotope analysis) and mineral compositions (by electron microprobe and ion microprobe). The whole rock has a composition of an H-chondrite minus the normal H-group metal and troilite content. The oxygen isotope composition is that of the silicates in the IIE iron meteorites and lies along an oxygen isotope fractionation line with the H-group chondrites. Trace elements in the metal confirm Watson is a new IIE iron. Whole rock Watson silicate shows an enrichment in K and P (each approximately 2X H-chondrites). The silicate inclusion has a highly equilibrated igneous (peridotite-like) texture with olivine largely poikilitic within low-Ca pyroxene: olivine (Fa20), opx (Fs17Wo3), capx (Fs9Wo14)(with very fine exsolution lamellae), antiperthite feldspar (An1-3Or5) with less than 1 micron exsolution lamellae (An1-3Or greater than 40), shocked feldspar with altered stoichiometry, minor whitlockite (also a poorly characterized interstitial phosphate-rich phase) and chromite, and only traces of metal and troilite. The individual silicate minerals have normal chondritic REE patterns, but whitlockite has a remarkable REE pattern. It is very enriched in light REE (La is 720X C1, and Lu is 90X C1, as opposed to usual chonditic values of approximately 300X and 100-150X, respectively) with a negative Eu anomaly. The enrichment of whole rock K is expressed both in an unusually high mean modal Or content of the feldspar, Or13, and in the presence of antiperthite.

Provenance and tectonic settings of sands from Puerto Peñasco, Desemboque and Bahia Kino beaches, Gulf of California, Sonora, México

NASA Astrophysics Data System (ADS)

Madhavaraju, J.; Tom, Milu; Lee, Yong IL; Balaram, V.; Ramasamy, S.; Carranza-Edwards, A.; Ramachandran, A.

2016-11-01

Textural, heavy minerals and geochemical (major, trace and rare earth elements) studies were undertaken on the sands from Puerto Peñasco, Desemboque and Bahia Kino beaches to determine the provenance and tectonic settings. Puerto Peñasco and Bahia Kino sands are coarse grained to fine grained, while Desemboque sands are fine grained. Geochemically, these sands are classified as arkose. The sands are depleted in most of the trace elements relative to upper continental crust (UCC), except for few trace elements (Sr, Rb and Ba), which are slightly enriched. High ΣREE content are observed in the Desemboque sands (94.43 ± 6.9) than in the Puerto Peñasco and Bahia Kino sands (51.58 ± 17.06; 72.38 ± 9.27; respectively). The chemical index of alteration (CIA) values of Puerto Peñasco, Desemboque and Bahia Kino sands (PP: 42 to 50; DE: 48 to 50; BK: 44 to 50: respectively) indicate the low intensity of chemical weathering in the source rocks. The tectonic discriminant-function-based multidimensional diagram shows arc and rift settings for Puerto Peñasco sands whereas rift setting for both Desemboque and Bahia Kino sands. The heavy mineral assemblage, immobile trace elements, REE patterns, elemental ratios such Eu/Eu*, (La/Lu)cn, La/Sc, Th/Sc, La/Co, Th/Co, and Cr/Th, various bivariate and ternary plots indicate the contribution of sediments from felsic composition. This interpretation is supported by the comparison of REE patterns of the Puerto Peñasco, Desemboque and Bahia Kino sands with the potential source rocks exposed nearby the study areas.

Sharp transition from ripple patterns to a flat surface for ion beam erosion of Si with simultaneous co-deposition of iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, K.; Broetzmann, M.; Hofsaess, H.

We investigate pattern formation on Si by sputter erosion under simultaneous co-deposition of Fe atoms, both at off-normal incidence, as function of the Fe surface coverage. The patterns obtained for 5 keV Xe ion irradiation at 30 Degree-Sign incidence angle are analyzed with atomic force microscopy. Rutherford backscattering spectroscopy of the local steady state Fe content of the Fe-Si surface layer allows a quantitative correlation between pattern type and Fe coverage. With increasing Fe coverage the patterns change, starting from a flat surface at low coverage (< 2 Multiplication-Sign 10{sup 15} Fe/cm{sup 2}) over dot patterns (2-8 Multiplication-Sign 10{sup 15}more » Fe/cm{sup 2}), ripples patterns (8-17 Multiplication-Sign 10{sup 15} Fe/cm{sup 2}), pill bug structures (1.8 Multiplication-Sign 10{sup 16} Fe/cm{sup 2}) and a rather flat surface with randomly distributed weak pits at high Fe coverage (>1.8 Multiplication-Sign 10{sup 16} Fe/cm{sup 2}). Our results confirm the observations by Macko et al. for 2 keV Kr ion irradiation of Si with Fe co-deposition. In particular, we also find a sharp transition from pronounced ripple patterns with large amplitude (rms roughness {approx} 18 nm) to a rather flat surface (rms roughness {approx} 0.5 nm). Within this transition regime, we also observe the formation of pill bug structures, i.e. individual small hillocks with a rippled structure on an otherwise rather flat surface. The transition occurs within a very narrow regime of the steady state Fe surface coverage between 1.7 and 1.8 Multiplication-Sign 10{sup 16} Fe/cm{sup 2}, where the composition of the mixed Fe-Si surface layer of about 10 nm thickness reaches the stoichiometry of FeSi{sub 2}. Phase separation towards amorphous iron silicide is assumed as the major contribution for the pattern formation at lower Fe coverage and the sharp transition from ripple patterns to a flat surface.« less

Interactions of microorganisms with rare earth ions and their utilization for separation and environmental technology.

PubMed

Moriwaki, Hiroshi; Yamamoto, Hiroki

2013-01-01

In recent years, rare earth elements (REEs) have been widely used in various modern technological devices and the global demand for REE has been increasing. The increased demand for REEs has led to environmental exposure or water pollution from rare earth metal mines and various commercial products. Therefore, the development of a safe technology for the separation and adsorption of REEs is very important from the perspective of green chemistry and environmental pollution. In this review, the application and mechanisms of microorganisms for the removal and extraction of REEs from aqueous solutions are described. In addition, the advantages in using microorganisms for REE adsorption and future studies on this topic are discussed.

Sustainability of rare earth elements chain: from production to food - a review.

PubMed

Turra, Christian

2018-02-01

Rare earth elements (REE) are a group of chemical elements that include lanthanoids (lanthanum to lutetium), scandium and yttrium. In the last decades, the REE demand in the industry and other areas has increased significantly. In general, REE have shown low concentrations in soils, plants, water and atmosphere, but they may accumulate in such environments due to anthropogenic inputs. In areas where there is REE contamination, the slow accumulation of these elements in the environment could become problematic. Many studies have shown environmental areas contaminated with REE and their toxic effects. Thus, it is important to review, in order to improve the current understanding of these elements in the environment, showing the effects of REE exposure in mining, soil, water, plants and food. Besides, there are few suppliers and a limited quantity of these elements in the world. This paper suggests options to improve the sustainability management of REE chain.

Quantitative analysis and temperature-induced variations of moiré pattern in fiber-coupled imaging sensors.

PubMed

Karbasi, Salman; Arianpour, Ashkan; Motamedi, Nojan; Mellette, William M; Ford, Joseph E

2015-06-10

Imaging fiber bundles can map the curved image surface formed by some high-performance lenses onto flat focal plane detectors. The relative alignment between the focal plane array pixels and the quasi-periodic fiber-bundle cores can impose an undesirable space variant moiré pattern, but this effect may be greatly reduced by flat-field calibration, provided that the local responsivity is known. Here we demonstrate a stable metric for spatial analysis of the moiré pattern strength, and use it to quantify the effect of relative sensor and fiber-bundle pitch, and that of the Bayer color filter. We measure the thermal dependence of the moiré pattern, and the achievable improvement by flat-field calibration at different operating temperatures. We show that a flat-field calibration image at a desired operating temperature can be generated using linear interpolation between white images at several fixed temperatures, comparing the final image quality with an experimentally acquired image at the same temperature.

Economic Assessment for Recycling Critical Metals From Hard Disk Drives Using a Comprehensive Recovery Process

NASA Astrophysics Data System (ADS)

Nguyen, Ruby Thuy; Diaz, Luis A.; Imholte, D. Devin; Lister, Tedd E.

2017-09-01

Since the 2011 price spike of rare earth elements (REEs), research on permanent magnet recycling has blossomed globally in an attempt to reduce future REE criticality. Hard disk drives (HDDs) have emerged as one feasible feedstock for recovering valuable REEs such as praseodymium, neodymium, and dysprosium. Nevertheless, current processes for recycling electronic waste only focus on certain metals as a result of feedstock and metal price uncertainties. In addition, there is a perception that recycling REEs is unprofitable. To shed some light on the economic viability of REE recycling from U.S. HDDs, this article combines techno-economic information of an electro-hydrometallurgical process with end-of-life HDD availability in a simulation model. The results showed that adding REE recovery to an HDD base and precious metal recovery process was profitable given current prices. Recovered REEs from U.S. HDDs could meet up to 5.2% rest-of-world (excluding China) neodymium magnet demand. Feedstock, aluminum, and gold prices are key factors to recycling profitability. REEs contributed 13% to the co-recycling profit.

The Caribbean-Colombian cretaceous igneous province: The internal anatomy of an oceanic plateau

NASA Astrophysics Data System (ADS)

Kerr, Andrew C.; Tarney, John; Marriner, Giselle F.; Nivia, Alvaro; Saunders, Andrew D.

The Late Cretaceous Caribbean—Colombian igneous province is one of the world's best-exposed examples of a plume-derived oceanic plateau. The buoyancy of the plateau (resulting from residual heat and thick crust) kept it from being totally subducted as it moved eastward with the Farallon Plate from its site of generation in the eastern Pacific and encountered a destructive plate margin. In effect, the plateau makes up much of the Caribbean Plate; it is well exposed around its margins, but more so in accreted terranes in western Colombia (including the well-known Gorgona komatiites and Bolívar mafic/ultramafic cumulates). Compositionally, the lavas of the plateau form three groups: (a) basalts, picrites, and komatiites with light-rare-earth-element (LREE)-depleted chondrite-normalised patterns; (b) basalts with LREE-enriched patterns; and (c) basalts with essentially flat REE patterns (the most dominant type) similar to many of the basalts from the Ontong Java Plateau. These three types demonstrate the heterogeneous nature of the mantle plume source region. The picrites and the komatiites seem to lie nearer the base of the plateau than the more homogeneous basalts; thus, the more MgO-rich melts may have been erupted before large magma chambers had a chance to develop. A reconstructed crustal cross section through the plateau consists of dunitic and pyroxenitic cumulates near the base which are overlain by layered olivine-rich gabbros and more isotropic gabbros. The lowermost eruptive sequence comprises compositionally heterogeneous picrites/komatiites overlain by more homogeneous pillow basalts. Spectacular hornblende-plagioclase veins cut the Bolívar assemblage and these may represent local partial melts of the plateau's base as it was thrusted onto the continent. Subduction-related batholiths and extrusive rocks found around the margin of the province are of two distinct ages; one suite represents pre-plateau collision-related volcanism whereas the other suite, slightly younger than the plateau, may be associated with obduction.

Printed Antenna Array with Flat-Top Radiation Pattern

NASA Astrophysics Data System (ADS)

Milijić, Marija R.; Nešić, Aleksandar D.; Milovanović, Bratislav D.; Nešić, Dušan A.

2018-04-01

A printed antenna array consisting of 10 wideband symmetrical pentagonal dipoles is presented. The feed network of impedance transformers is employed to provide appropriate amplitude and phase distribution necessary to obtain flat top beam pattern. The measured results demonstrate excellent radiation characteristics including 38° flat gain region with maximum ripple of 3.5 dB at the centre frequency. Furthermore, the proposed antenna that is placed in corner reflector with angle of 60° has good gain (17 dBi) and side lobe suppression (18.9 dB). Although it is designed at the centre frequency fc=12 GHz, it was shown to be capable of shaping a good flat top radiation pattern within a fractional bandwidth at least 6 % of centre frequency. Also, proposed antenna features cheap, simple and easy fabrication that makes it suitable for mass production.

Effects of organic ligands on fractionation of rare earth elements (REEs) in hydroponic plants: an application to the determination of binding capacities by humic acid for modeling.

PubMed

Ding, ShiMing; Liang, Tao; Zhang, ChaoSheng; Yan, JunCai; Zhang, ZiLi

2006-12-01

Previous studies have revealed the fractionation processes of rare earth elements (REEs) in hydroponic plants, with a heavy REE (HREE, the elements from Gd to Lu) enrichment in leaves. In this study, effects on the HREE enrichment in soybean leaves with additions of carboxylic acids (acetate, malate, citrate, NTA, EDTA and DTPA) and two soil humic acids (HAs) were investigated. REE speciation in carboxylic acid and HA solutions was simulated using Visual MINTEQ and Model V, respectively. The results showed that the effects caused by carboxylic acids were strongly dependent on the differences between their binding strengths for light REEs (LREEs, the elements from La to Eu) and those for HREEs. A good correlation existed between these effects and the changes of free REE ions in solutions. This relationship was also observed for the HA treatments, provided that the intrinsic equilibrium constants of REEs for cation-proton exchange with HA (i.e., pK(MHA)) in Model V were estimated using a free-energy relationship with the stability constants for REE complexation with lactic acid. It is suggested that this set of pK(MHA) values is more suitable for use in Model V for the simulation of REE complexation with HA.

Crystal-chemistry and partitioning of REE in whitlockite

NASA Technical Reports Server (NTRS)

Colson, R. O.; Jolliff, B. L.

1993-01-01

Partitioning of Rare Earth Elements (REE) in whitlockite is complicated by the fact that two or more charge-balancing substitutions are involved and by the fact that concentrations of REE in natural whitlockites are sufficiently high such that simple partition coefficients are not expected to be constant even if mixing in the system is completely ideal. The present study combines preexisting REE partitioning data in whitlockites with new experiments in the same compositional system and at the same temperature (approximately 1030 C) to place additional constraints on the complex variations of REE partition coefficients and to test theoretical models for how REE partitioning should vary with REE concentration and other compositional variables. With this data set, and by combining crystallographic and thermochemical constraints with a SAS simultaneous-equation best-fitting routine, it is possible to infer answers to the following questions: what is the speciation on the individual sites Ca(B), Mg, and Ca(IIA) (where the ideal structural formula is Ca(B)18 Mg2Ca(IIA)2P14O56); how are REE's charge-balanced in the crystal; and is mixing of REE in whitlockite ideal or non-ideal. This understanding is necessary in order to extrapolate derived partition coefficients to other compositional systems and provides a broadened understanding of the crystal chemistry of whitlockite.

Distribution and source of rare earth elements in PM2.5 in Xiamen, China.

PubMed

Wang, Shanshan; Yu, Ruilian; Hu, Gongren; Hu, Qichao; Zheng, Quan

2017-12-01

Particulate matter with diameter ≤2.5 µm (PM 2.5 ) is a serious atmospheric pollutant. Composition and source analyses are essential for controlling PM 2.5 . Rare earth elements (REEs) have received little attention as a component of PM 2.5 . In the present study, PM 2.5 samples were collected in urban and suburban areas in Xiamen and analyzed for REEs. The concentration range of total REEs (∑REE) is 12.07 to 98.45 mg/kg, with a mean of 38.53 mg/kg, in urban PM 2.5 and 16.44 to 160.62 mg/kg, with a mean of 42.94 mg/kg, in suburban PM 2.5 . Light REE concentrations are higher in suburban PM 2.5 , whereas heavy REE concentrations are higher in urban PM 2.5 , implying distinct sources of REEs in urban and suburban PM 2.5 . The scatter plots of δEu-∑REE and La-Ce-Sm suggest that REEs in urban PM 2.5 originate from gasoline- and diesel-vehicle exhaust, whereas those in suburban PM 2.5 are mainly influenced by gasoline-vehicle exhaust. Environ Toxicol Chem 2017;36:3217-3222. © 2017 SETAC. © 2017 SETAC.

Formation of carbonatite-related giant rare-earth-element deposits by the recycling of marine sediments

PubMed Central

Hou, Zengqian; Liu, Yan; Tian, Shihong; Yang, Zhiming; Xie, Yuling

2015-01-01

Carbonatite-associated rare-earth-element (REE) deposits are the most significant source of the world’s REEs; however, their genesis remains unclear. Here, we present new Sr-Nd-Pb and C-O isotopic data for Cenozoic carbonatite-hosted giant REE deposits in southwest China. These REE deposits are located along the western margin of the Yangtze Craton that experienced Proterozoic lithospheric accretion, and controlled by Cenozoic strike-slip faults related to Indo-Asian continental collision. The Cenozoic carbonatites were emplaced as stocks or dykes with associated syenites, and tend to be extremely enriched in Ba, Sr, and REEs and have high 87Sr/86Sr ratios (>0.7055). These carbonatites were likely formed by melting of the sub-continental lithospheric mantle (SCLM), which had been previously metasomatized by high-flux REE- and CO2-rich fluids derived from subducted marine sediments. The fertility of these carbonatites depends on the release of REEs from recycled marine sediments and on the intensity of metasomatic REE refertilization of the SCLM. We suggest that cratonic edges, particularly along ancient convergent margins, possess the optimal configuration for generating giant REE deposits; therefore, areas of metamorphic basement bounded or cut by translithospheric faults along cratonic edges have a high potential for such deposits. PMID:26035414

Characterization of Rare Earth Elements in in Clay Deposits Associated with Central Appalachian Coal Seams

NASA Astrophysics Data System (ADS)

Scott, M.; Verba, C.; Falcon, A.; Poston, J.; McKoy, M.

2017-12-01

Because of their multiple uses in clean energy technologies, rare earth elements (REE) are critical for national economic and energy security. With no current domestic source, supply remains a major concern for domestic security. Underclay - specifically the layer of stratum beneath a coal bed - is a potentially rich source of REE. This study focuses on the characterization and ion exchange recovery of REE from underclay samples from the Lower Freeport, Middle Kittanning, and Pittsburgh coal seams in West Virginia. Multimodal techniques provided quantitative assessments of REE-bearing mineral phases in select underclays and the influence of organic acid rock treatment on the recovery of REE from both exchangeable and crystalline mineral phases present. All samples are from extensively weathered horizons that contain abundant kaolinite and illite. Total REE concentrations range from 250-450 ppm and all samples have a HREE/LEEE ratio >20%. Rare earth element bearing minerals identified in the clay are monazite, xenotime, florencite, and crandallite. Our selective recovery approach is designed to isolate and recover REE through partial dissolution of the clay matrix and ion exchange rather than dissolution/recovery of phosphate or aluminosilicate bound REE. These results provide a better understanding of coal seam underclay, the affinity of REEs for specific ligands and colloids, and how the rock and ligands respond to different chemical treatments. These processes are important to the development and commercialization of efficient and cost effective methods to extract REE from domestic geologic deposits and recover into salable forms.

Extraction of rare earth elements from a contaminated cropland soil using nitric acid, citric acid, and EDTA.

PubMed

Tang, Hailong; Shuai, Weitao; Wang, Xiaojing; Liu, Yangsheng

2017-08-01

Rare earth elements (REEs) contamination to the surrounding soil has increased the concerns of health risk to the local residents. Soil washing was first attempted in our study to remediate REEs-contaminated cropland soil using nitric acid, citric acid, and ethylene diamine tetraacetic acid (EDTA) for soil decontamination and possible recovery of REEs. The extraction time, washing agent concentration, and pH value of the washing solution were optimized. The sequential extraction analysis proposed by Tessier was adopted to study the speciation changes of the REEs before and after soil washing. The extract containing citric acid was dried to obtain solid for the X-ray fluorescence (XRF) analysis. The results revealed that the optimal extraction time was 72 h, and the REEs extraction efficiency increased as the agent concentration increased from 0.01 to 0.1 mol/L. EDTA was efficient to extract REEs over a wide range of pH values, while citric acid was around pH 6.0. Under optimized conditions, the average extraction efficiencies of the major REEs in the contaminated soil were 70.96%, 64.38%, and 62.12% by EDTA, nitric acid, and citric acid, respectively. The sequential extraction analyses revealed that most soil-bounded REEs were mobilized or extracted except for those in the residual fraction. Under a comprehensive consideration of the extraction efficiency and the environmental impact, citric acid was recommended as the most suitable agent for extraction of the REEs from the contaminated cropland soils. The XRF analysis revealed that Mn, Al, Si, Pb, Fe, and REEs were the major elements in the extract indicating a possibile recovery of the REEs.

Resting energy expenditure prediction in recreational athletes of 18-35 years: confirmation of Cunningham equation and an improved weight-based alternative.

PubMed

ten Haaf, Twan; Weijs, Peter J M

2014-01-01

Resting energy expenditure (REE) is expected to be higher in athletes because of their relatively high fat free mass (FFM). Therefore, REE predictive equation for recreational athletes may be required. The aim of this study was to validate existing REE predictive equations and to develop a new recreational athlete specific equation. 90 (53 M, 37 F) adult athletes, exercising on average 9.1 ± 5.0 hours a week and 5.0 ± 1.8 times a week, were included. REE was measured using indirect calorimetry (Vmax Encore n29), FFM and FM were measured using air displacement plethysmography. Multiple linear regression analysis was used to develop a new FFM-based and weight-based REE predictive equation. The percentage accurate predictions (within 10% of measured REE), percentage bias, root mean square error and limits of agreement were calculated. Results: The Cunningham equation and the new weight-based equation REE(kJ / d) = 49.940* weight(kg) + 2459.053* height(m) - 34.014* age(y) + 799.257* sex(M = 1,F = 0) + 122.502 and the new FFM-based equation REE(kJ / d) = 95.272*FFM(kg) + 2026.161 performed equally well. De Lorenzo's equation predicted REE less accurate, but better than the other generally used REE predictive equations. Harris-Benedict, WHO, Schofield, Mifflin and Owen all showed less than 50% accuracy. For a population of (Dutch) recreational athletes, the REE can accurately be predicted with the existing Cunningham equation. Since body composition measurement is not always possible, and other generally used equations fail, the new weight-based equation is advised for use in sports nutrition.

Resting energy expenditure per lean body mass determined by indirect calorimetry and bioelectrical impedance analysis in cats.

PubMed

Center, S A; Warner, K L; Randolph, J F; Wakshlag, J J; Sunvold, G D

2011-01-01

Resting energy expenditure (REE) approximates ≥60% of daily energy expenditure (DEE). Accurate REE determination could facilitate sequential comparisons among patients and diseases if normalized against lean body mass (LBM). (1) Validate open-flow indirect calorimetry (IC) system and multifrequency bioelectrical impedance analysis (MF-BIA) to determine REE and LBM, respectively, in healthy nonsedated cats of varied body conditions; (2) normalize REE against LBM. Fifty-seven adult neutered domestic short-haired cats with stable BW. Continuous (45-min) IC-measurements determined least observed metabolism REE. Cage gas flow regulated with mass flow controllers was verified using nitrogen dilution; span gases calibrated gas measurements. Respiratory quotient accuracy was verified using alcohol combustion. IC-REE was compared to DEE, determined using doubly labeled water. MF-BIA LBM was validated against criterion references (deuterium, sodium bromide). Intra- and interassay variation was determined for IC and MF-BIA. Mean IC-REE (175 ± 38.7 kcal; 1.5-14% intra- and interassay CV%) represented 61 ± 14.3% of DEE. Best MF-BIA measurements were collected in sternal recumbency and with electrodes in neck-tail configuration. MF-BIA LBM was not significantly different from criterion references and generated LBM interassay CV% of 6.6-10.1%. Over- and underconditioned cats had significantly (P ≤ .05) lower and higher IC-REE (kcal/kg) respectively, compared with normal-conditioned cats. However, differences resolved with REE/LBM (approximating 53 ± 10.3 kcal/LBM [kg]). IC and MF-BIA validated herein reasonably estimate REE and LBM in cats. REE/LBM(kg) may permit comparison of energy utilization in sequential studies or among different cats. Copyright © 2011 by the American College of Veterinary Internal Medicine.

Facile Arsenazo III-Based Assay for Monitoring Rare Earth Element Depletion from Cultivation Media for Methanotrophic and Methylotrophic Bacteria

PubMed Central

Hogendoorn, Carmen; Roszczenko-Jasińska, Paula; Martinez-Gomez, N. Cecilia; de Graaff, Johann; Grassl, Patrick; Pol, Arjan; Op den Camp, Huub J. M.

2018-01-01

ABSTRACT Recently, methanotrophic and methylotrophic bacteria were found to utilize rare earth elements (REEs). To monitor the REE content in culture media of these bacteria, we have developed a rapid screening method using the Arsenazo III (AS III) dye for spectrophotometric REE detection in the low μM (0.1 to 10 μM) range. We designed this assay to follow LaIII and EuIII depletion from the culture medium by the acidophilic verrucomicrobial methanotroph Methylacidiphilum fumariolicum strain SolV. The assay can also be modified to screen the uptake of other REEs, such as PrIII, or to monitor the depletion of LaIII from growth media in neutrophilic methylotrophs such as Methylobacterium extorquens strain AM1. The AS III assay presents a convenient and fast detection method for REE levels in culture media and is a sensitive alternative to inductively coupled plasma mass spectrometry (ICP-MS) or atomic absorption spectroscopy (AAS). IMPORTANCE REE-dependent bacterial metabolism is a quickly emerging field, and while the importance of REEs for both methanotrophic and methylotrophic bacteria is now firmly established, many important questions, such as how these insoluble elements are taken up into cells, are still unanswered. Here, an Arsenazo III dye-based assay has been developed for fast, specific, and sensitive determination of REE content in different culture media. This assay presents a useful tool for optimizing cultivation protocols, as well as for routine REE monitoring during bacterial growth without the need for specialized analytical instrumentation. Furthermore, this assay has the potential to promote the discovery of other REE-dependent microorganisms and can help to elucidate the mechanisms for acquisition of REEs by methanotrophic and methylotrophic bacteria. PMID:29453257

Facile Arsenazo III-Based Assay for Monitoring Rare Earth Element Depletion from Cultivation Media for Methanotrophic and Methylotrophic Bacteria.

PubMed

Hogendoorn, Carmen; Roszczenko-Jasińska, Paula; Martinez-Gomez, N Cecilia; de Graaff, Johann; Grassl, Patrick; Pol, Arjan; Op den Camp, Huub J M; Daumann, Lena J

2018-04-15

Recently, methanotrophic and methylotrophic bacteria were found to utilize rare earth elements (REEs). To monitor the REE content in culture media of these bacteria, we have developed a rapid screening method using the Arsenazo III (AS III) dye for spectrophotometric REE detection in the low μM (0.1 to 10 μM) range. We designed this assay to follow La III and Eu III depletion from the culture medium by the acidophilic verrucomicrobial methanotroph Methylacidiphilum fumariolicum strain SolV. The assay can also be modified to screen the uptake of other REEs, such as Pr III , or to monitor the depletion of La III from growth media in neutrophilic methylotrophs such as Methylobacterium extorquens strain AM1. The AS III assay presents a convenient and fast detection method for REE levels in culture media and is a sensitive alternative to inductively coupled plasma mass spectrometry (ICP-MS) or atomic absorption spectroscopy (AAS). IMPORTANCE REE-dependent bacterial metabolism is a quickly emerging field, and while the importance of REEs for both methanotrophic and methylotrophic bacteria is now firmly established, many important questions, such as how these insoluble elements are taken up into cells, are still unanswered. Here, an Arsenazo III dye-based assay has been developed for fast, specific, and sensitive determination of REE content in different culture media. This assay presents a useful tool for optimizing cultivation protocols, as well as for routine REE monitoring during bacterial growth without the need for specialized analytical instrumentation. Furthermore, this assay has the potential to promote the discovery of other REE-dependent microorganisms and can help to elucidate the mechanisms for acquisition of REEs by methanotrophic and methylotrophic bacteria. Copyright © 2018 Hogendoorn et al.

Critical Zone Weathering and Your Smartphone: Understanding How Mineral Decomposition and Colloid Redistribution Can Generate Rare Earth Element Deposits

NASA Astrophysics Data System (ADS)

Bern, C.; Foley, N.

2014-12-01

Rare earth elements (REE's) are crucial in the manufacture of smartphones and many other high tech devices. Increasing global demand and relatively narrow geographic sourcing have promoted interest in understanding REE deposit genesis and distribution. Highly weathered, clay-hosted, ion-exchange type deposits in southern China are the source of much of the world's production of the more valuable heavy REEs. Such deposits form as REE-bearing minerals weather and REEs released to solution in ionic form are retained by negatively charged exchange sites on clay minerals. We are investigating the potential for ion-exchange REE deposits in the Piedmont of the southeastern United States, where slow erosion rates have preserved thick (up to 20 m) regolith, as required for such deposits. The Liberty Hill pluton outcrops as coarse-grained biotite-amphibole granite and quartz monzonite over nearly 400 km2 in South Carolina, and has an age of 305 Ma (new SHRIMP ion microprobe zircon age). In weathered profiles over the pluton, ion-exchangeable REE content ranges from 8 to 580 ppm and accounts for 2 to 80% of bulk REE content. Elemental and heavy mineral distributions suggest the wide ranging differences in leachability may be attributable to the amount and distribution of resistant REE-bearing phases (e.g., monazite) relative to more easily weathered phases (e.g., allanite) in the parent granite. The REEs show little mobility within the regolith, indicating the effectiveness of the ion-exchange retention mechanism. In contrast, vertical redistribution of colloidal material shows maximum accumulations at ~1 m depth, as traced by the newly developed dual-phase (colloids vs. solution) mass balance model. The contrast suggests redistributed colloidal material has minimal influence on REE mobilization or retention. Conditions and processes necessary for ion-exchange REE deposit development exist in the Piedmont, but their presence will depend upon favorable parent rock mineralogy.

Age-Dependent Changes in Resting Energy Expenditure (REE): Insights from Detailed Body Composition Analysis in Normal and Overweight Healthy Caucasians

PubMed Central

Geisler, Corinna; Braun, Wiebke; Pourhassan, Maryam; Schweitzer, Lisa; Glüer, Claus-Christian; Bosy-Westphal, Anja; Müller, Manfred J.

2016-01-01

Age-related changes in organ and tissue masses may add to changes in the relationship between resting energy expenditure (REE) and fat free mass (FFM) in normal and overweight healthy Caucasians. Secondary analysis using cross-sectional data of 714 healthy normal and overweight Caucasian subjects (age 18–83 years) with comprehensive information on FFM, organ and tissue masses (as assessed by magnetic resonance imaging (MRI)), body density (as assessed by Air Displacement Plethysmography (ADP)) and hydration (as assessed by deuterium dilution (D2O)) and REE (as assessed by indirect calorimetry). High metabolic rate organs (HMR) summarized brain, heart, liver and kidney masses. Ratios of HMR organs and muscle mass (MM) in relation to FFM were considered. REE was calculated (REEc) using organ and tissue masses times their specific metabolic rates. REE, FFM, specific metabolic rates, the REE-FFM relationship, HOMA, CRP, and thyroid hormone levels change with age. The age-related decrease in FFM explained 59.7% of decreases in REE. Mean residuals of the REE-FFM association were positive in young adults but became negative in older subjects. When compared to young adults, proportions of MM to FFM decreased with age, whereas contributions of liver and heart did not differ between age groups. HOMA, TSH and inflammation (plasma CRP-levels) explained 4.2%, 2.0% and 1.4% of the variance in the REE-FFM residuals, but age and plasma T3-levels had no effects. HMR to FFM and MM to FFM ratios together added 11.8% on to the variance of REE-FFM residuals. Differences between REE and REEc increased with age, suggesting age-related changes in specific metabolic rates of organs and tissues. This bias was partly explained by plasmaT3-levels. Age-related changes in REE are explained by (i) decreases in fat free mass; (ii) a decrease in the contributions of organ and muscle masses to FFM; and (iii) decreases in specific organ and tissue metabolic rates. Age-dependent changes in the REE-FFMassociation are explained by composition of FFM, inflammation and thyroid hormones. PMID:27258302

Age-Dependent Changes in Resting Energy Expenditure (REE): Insights from Detailed Body Composition Analysis in Normal and Overweight Healthy Caucasians.

PubMed

Geisler, Corinna; Braun, Wiebke; Pourhassan, Maryam; Schweitzer, Lisa; Glüer, Claus-Christian; Bosy-Westphal, Anja; Müller, Manfred J

2016-06-01

Age-related changes in organ and tissue masses may add to changes in the relationship between resting energy expenditure (REE) and fat free mass (FFM) in normal and overweight healthy Caucasians. Secondary analysis using cross-sectional data of 714 healthy normal and overweight Caucasian subjects (age 18-83 years) with comprehensive information on FFM, organ and tissue masses (as assessed by magnetic resonance imaging (MRI)), body density (as assessed by Air Displacement Plethysmography (ADP)) and hydration (as assessed by deuterium dilution (D₂O)) and REE (as assessed by indirect calorimetry). High metabolic rate organs (HMR) summarized brain, heart, liver and kidney masses. Ratios of HMR organs and muscle mass (MM) in relation to FFM were considered. REE was calculated (REEc) using organ and tissue masses times their specific metabolic rates. REE, FFM, specific metabolic rates, the REE-FFM relationship, HOMA, CRP, and thyroid hormone levels change with age. The age-related decrease in FFM explained 59.7% of decreases in REE. Mean residuals of the REE-FFM association were positive in young adults but became negative in older subjects. When compared to young adults, proportions of MM to FFM decreased with age, whereas contributions of liver and heart did not differ between age groups. HOMA, TSH and inflammation (plasma CRP-levels) explained 4.2%, 2.0% and 1.4% of the variance in the REE-FFM residuals, but age and plasma T3-levels had no effects. HMR to FFM and MM to FFM ratios together added 11.8% on to the variance of REE-FFM residuals. Differences between REE and REEc increased with age, suggesting age-related changes in specific metabolic rates of organs and tissues. This bias was partly explained by plasmaT3-levels. Age-related changes in REE are explained by (i) decreases in fat free mass; (ii) a decrease in the contributions of organ and muscle masses to FFM; and (iii) decreases in specific organ and tissue metabolic rates. Age-dependent changes in the REE-FFMassociation are explained by composition of FFM, inflammation and thyroid hormones.

Prediction equation of resting energy expenditure in an adult Spanish population of obese adult population.

PubMed

de Luis, D A; Aller, R; Izaola, O; Romero, E

2006-01-01

The aim of our study was to evaluate the accuracy of the equations to estimate REE in obese patents and develop a new equation in our obese population. A population of 200 obesity outpatients was analyzed in a prospective way. The following variables were specifically recorded: age, weight, body mass index (BMI), waist circumference, and waist-to-hip ratio. Basal glucose, insulin, and TSH (thyroid-stimulating hormone) were measured. An indirect calorimetry and a tetrapolar electrical bioimpedance were performed. REE measured by indirect calorimetry was compared with REE obtained by prediction equations to obese or nonobese patients. The mean age was 44.8 +/- 16.81 years and the mean BMI 34.4 +/- 5.3. Indirect calorimetry showed that, as compared to women, men had higher resting energy expenditure (REE) (1,998.1 +/- 432 vs. 1,663.9 +/- 349 kcal/day; p < 0.05) and oxygen consumption (284.6 +/- 67.7 vs. 238.6 +/- 54.3 ml/min; p < 0.05). Correlation analysis among REE obtained by indirect calorimetry and REE predicted by prediction equations showed the next data; Berstein's equation (r = 0.65; p < 0.05), Harris Benedict's equation (r = 0.58; p < 0.05), Owen's equation (r = 0.56; p < 0.05), Ireton's equation (r = 0.58; p < 0.05) and WHO's equation (r = 0.57; p < 0.05). Both the Berstein's and the Ireton's equations overpredicted REE and showed nonsignificant mean differences form measured REE. The Owen's, WHO's, and Harris Benedict's equations underpredicted REE. Our male prediction equation was REE = 58.6 + (6.1 x weight (kg)) + (1,023.7 x height (m)) - (9.5 x age). The female model was REE = 1,272.5 + (9.8 x weight (kg)) - (61.6 x height (m)) - (8.2 x age). Our prediction equations showed a nonsignificant difference with REE measured (-3.7 kcal/day) with a significant correlation coefficient (r = 0.67; p < 0.05). Previously developed prediction equations overestimated and underestimated REE measured. WHO equation developed in normal weight individuals provided the closest values. The two new equations (male and female equations) developed in our study had a good accuracy. Copyright 2006 S. Karger AG, Basel.

Rare-earth leaching from Florida phosphate rock in wet-process phosphoric acid production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Haijun; Zhang, Patrick; Jin, Zhen

Phosphorite, or phosphate rock, is the most significant secondary rare-earth resource. It contains high amounts of phosphate-bearing minerals along with low contents of rare earth elements (REEs). In Florida, about 19 Mt of phosphate rock are mined annually and most are used to manufacture fertilizers using a wet process, in which sulfuric acid reacts with phosphates to produce phosphoric acid and phosphogypsum. In the wet process, REEs are also leached out into solution and eventually get lost in the leaching residue and phosphate fertilizer. Recovering REEs from Florida phosphate rock in the wet process will be beneficial to broadening rare-earthmore » availability, improving the quality of phosphoric acid product and protecting the environment. Here, this study focuses on the influences of wet-process operating conditions on REE leaching efficiency. The results indicate that REE leaching efficiency increases with phosphoric acid addition in the initial pulp. At a temperature of 75 °C, a stoichiometric ratio of sulfuric acid (H2 SO4 ) to calcium oxide (CaO) of 1.05 and a weight ratio of liquid to solid of 3.5, REE leaching efficiency reached a relatively high value of 52.82 percent. The trends of REE leaching efficiency were similar to those for phosphoric acid (P2O5 ). Extensive tests on the leaching residue showed that during leaching, about 90 percent of the REEs were released from the phosphate rock but only 52.82 percent ended up in the leaching solution. This phenomenon can be attributed to two factors: (1) the effect of phosphate ions (PO43-) in the solution, which caused REE ions to form REE phosphates and be precipitated into the leaching residue, and (2) the influence of large amounts of anions such as sulfate (SO42-), dihydrogen phosphate (H2 PO4-) and hydrogen phosphate (HPO42-) anions as well as the polar molecule H3 PO4 , which surrounded the REE cations and formed an ion atmosphere that prevented the PO43- from contacting and combining with REE cations. Finally, interaction of these two opposite effects determined the REE distribution between leaching solution and residue.« less

Rare-earth leaching from Florida phosphate rock in wet-process phosphoric acid production

DOE PAGES

Liang, Haijun; Zhang, Patrick; Jin, Zhen; ...

2017-08-01

Phosphorite, or phosphate rock, is the most significant secondary rare-earth resource. It contains high amounts of phosphate-bearing minerals along with low contents of rare earth elements (REEs). In Florida, about 19 Mt of phosphate rock are mined annually and most are used to manufacture fertilizers using a wet process, in which sulfuric acid reacts with phosphates to produce phosphoric acid and phosphogypsum. In the wet process, REEs are also leached out into solution and eventually get lost in the leaching residue and phosphate fertilizer. Recovering REEs from Florida phosphate rock in the wet process will be beneficial to broadening rare-earthmore » availability, improving the quality of phosphoric acid product and protecting the environment. Here, this study focuses on the influences of wet-process operating conditions on REE leaching efficiency. The results indicate that REE leaching efficiency increases with phosphoric acid addition in the initial pulp. At a temperature of 75 °C, a stoichiometric ratio of sulfuric acid (H2 SO4 ) to calcium oxide (CaO) of 1.05 and a weight ratio of liquid to solid of 3.5, REE leaching efficiency reached a relatively high value of 52.82 percent. The trends of REE leaching efficiency were similar to those for phosphoric acid (P2O5 ). Extensive tests on the leaching residue showed that during leaching, about 90 percent of the REEs were released from the phosphate rock but only 52.82 percent ended up in the leaching solution. This phenomenon can be attributed to two factors: (1) the effect of phosphate ions (PO43-) in the solution, which caused REE ions to form REE phosphates and be precipitated into the leaching residue, and (2) the influence of large amounts of anions such as sulfate (SO42-), dihydrogen phosphate (H2 PO4-) and hydrogen phosphate (HPO42-) anions as well as the polar molecule H3 PO4 , which surrounded the REE cations and formed an ion atmosphere that prevented the PO43- from contacting and combining with REE cations. Finally, interaction of these two opposite effects determined the REE distribution between leaching solution and residue.« less

Influence of water drinking on resting energy expenditure in overweight children.

PubMed

Dubnov-Raz, G; Constantini, N W; Yariv, H; Nice, S; Shapira, N

2011-10-01

It was previously demonstrated that drinking water significantly elevates the resting energy expenditure (REE) in adults, and that low water intake is associated with obesity and lesser success in weight reduction. This study addressed the potential of water drinking to increase the REE in children, as an additional tool for weight management. To examine the effect of drinking water on the REE of overweight children. A total of 21 overweight, otherwise-healthy children (age 9.9±1.4 years, 11 males) drank 10 ml kg(-1) cold water (4 °C). REE was measured before and after water ingestion, for 66 min. The main outcome measure was the change in mean REE from baseline values. Immediately after drinking water, there was a transient decrease in REE, from a baseline value of 3.32±1.15 kilojoule (kJ) per min to 2.56±0.66 kJ per min at minute 3 (P=0.005). A subsequent rise in REE was then observed, which was significantly higher than baseline after 24 min (3.89±0.78 kJ/min (P=0.021)), and at most time points thereafter. Maximal mean REE values were seen at 57 min after water drinking (4.16±1.43 kJ per min (P=0.004)), which were 25% higher than baseline. REE was significantly correlated with age, height, weight and fat-free mass; the correlations with maximal REE values after water drinking were stronger than with baseline REE values. This study demonstrated an increase of up to 25% in REE following the drinking of 10 ml kg(-1) of cold water in overweight children, lasting for over 40 min. Consuming the recommended daily amount of water for children could result in an energy expenditure equivalent to an additional weight loss of about 1.2 kg per year. These findings reinforce the concept of water-induced REE elevation shown in adults, suggesting that water drinking could assist overweight children in weight loss or maintenance, and may warrant emphasis in dietary guidelines against the obesity epidemic.

Late Cenzoic rhyolites from the Kern Plateau, southern Sierra Nevada, California.

USGS Publications Warehouse

Bacon, C.R.; Duffield, W.A.

1981-01-01

Four late Cenozoic rhyolite domes lie atop the Kern Plateau, 30 to 40km S-SE of Mount Whitney. K-Ar and 40Ar/39Ar dating shows that Monache, Templeton, and Little Templeton Mountains are all about 2.4Ma old; a small dome nearby is approx 0.2Ma old. The three older rhyolites have SiO2 = 73-74% and have steep, fractionated rare earth element (REE) patterns; the youngest has SiO2 = 76% and a concave-upward REE pattern with a large negative Eu anomaly, Monache rhyolite contains the unusual phenocryst assemblage almandine + fayalite + biotite + oligoclase. The 2.4Ma old rocks may be nearly unmodified partial melts of crustal sources, whereas the 0.2Ma old rhyolite may be a product of relatively shallow differentiation. The rhyolites and nearby basalts are coeval with mafic and silicic volcanic rocks in the Coso Range about 40km to the SE. Their generation and eruption may reflect intense tectonic extension at the margin of the Basin and Range province and concomitant relaxation of compressive stress in a W- NW direction, allowing melts to reach the surface in the adjacent Sierra Nevada.-Authors

REE chemistry and Sm-Nd systematics of late Archean weathering profiles in the Fortescue Group, Western Australia

NASA Technical Reports Server (NTRS)

MacFarlane, A. W.; Danielson, A.; Holland, H. D.; Jacobsen, S. B.

1994-01-01

Two weathering profiles, each consisting of an upper, sericite-rich zone and a lower, chlorite-rich zone, are preserved between flows of the Mt. Roe Basalt in the Fortescue Group, Hamersley Basin, Western Australia. REE concentrations in samples from these two profiles, which originally developed ca 2,760 Ma, show large variations depending on stratigraphic position. LREE abundances and (La/Yb)N are greatest at depths of 3-6 m below the paleosurface of the Mt. Roe #1 profile and are somewhat lower in samples above this level. The LREEs reach concentrations 6-9 times greater than in the underlying basalt, and thus appear to have been mobilized downward in the paleosol and concentrated in its middle part. LREE concentrations in the #2 profile show a similar distribution but with a sharp increase in all REE concentrations within 50 cm of the paleosurface. The distinction between the REE profiles in the two paleosols may be related to the difference in the overlying material. The #1 paleosol is overlain by a few meters of sediments and then by basalt, whereas the #2 paleosol is directly overlain by basalt. The LREEs appear to have been mobilized both during chemical weathering of the parental basalt and during later lower-greenschist-facies metamorphism and metasomatism of the paleosols. Remobilization of the REEs during the regional metamorphism of the Fortescue Group is confirmed by a whole-rock Sm-Nd reference isochron of Mt. Roe #1 samples with an age of 2,151 +/- 360 Ma. Variable initial 143Nd/144Nd values of unweathered basalt samples which may represent the paleosol protolith prevents a confident determination of the magnitude of LREE mobility. Both the initial mobilization of the REEs during weathering and the metasomatic remobilization appear to have taken place under redox conditions where Ce was present dominantly as Ce3+, because Ce anomalies are not developed within the sericite zone samples regardless of concentration. Europium anomalies in the paleoweathering profile are somewhat variable and were probably modified by mobilization of Eu2+ at metamorphic conditions. In all samples, the HREEs appear to have been relatively immobile and correlate with Al, Ti, Cr, V, Zr, and Nb. Sm-Nd systematics and REE patterns of four unweathered basalt samples indicate derivation of the Mt. Roe Basalts from a heterogeneous and enriched source having epsilon Nd between -4.0 and -7.4. Initial 143Nd/144Nd values of these basalts are even lower than those reported by NELSON et al. (1992) for Fortescue Group basalts and indicate a substantial crustal component in the generation of Mt. Roe Basalts.

Provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico unraveled by geochemical analysis

NASA Astrophysics Data System (ADS)

Armstrong-Altrin, John S.; Machain-Castillo, María Luisa; Rosales-Hoz, Leticia; Carranza-Edwards, Arturo; Sanchez-Cabeza, Joan-Albert; Ruíz-Fernández, Ana Carolina

2015-03-01

The aim of this work is to constrain the provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico (~1089-1785 m water depth). To achieve this, 10 piston sediment cores (~5-5.5 m long) were studied for mineralogy, major, trace and rare earth element geochemistry. Samples were analyzed at three core sections, i.e. upper (0-1 cm), middle (30-31 cm) and lower (~300-391 cm). The textural study reveals that the core sediments are characterized by silt and clay fractions. Radiocarbon dating of sediments for the cores at different levels indicated a maximum of ~28,000 year BP. Sediments were classified as shale. The chemical index of alteration (CIA) values for the upper, middle, and lower sections revealed moderate weathering in the source region. The index of chemical maturity (ICV) and SiO2/Al2O3 ratio indicated low compositional maturity for the core sediments. A statistically significant correlation observed between total rare earth elements (∑REE) versus Al2O3 and Zr indicated that REE are mainly housed in detrital minerals. The North American Shale Composite (NASC) normalized REE patterns, trace element concentrations such as Cr, Ni and V, and the comparison of REE concentrations in sediments and source rocks indicated that the study area received sediments from rocks intermediate between felsic and mafic composition. The enrichment factor (EF) results indicated that the Cd and Zn contents of the upper section sediments were influenced by an anthropogenic source. The trace element ratios and authigenic U content of the core sediments indicated the existence of an oxic depositional environment.

Foliation development and reaction softening by dissolution and precipitation in the transformation of granodiorite to orthogneiss, Glastonbury Complex, Connecticut, U.S.A

USGS Publications Warehouse

Wintsch, R.P.; Aleinikoff, J.N.; Yi, K.

2005-01-01

Textures, microstructures, and patterns of chemical zoning in minerals in a granodioritic orthogneiss in the Glastonbury Complex, Connecticut, lead to the interpretation that foliation development was facilitated by retrograde hydration reactions in the presence of an aqueous fluid. Incomplete replacement of the metastable magmatic minerals K-feldspar + hastingsite + magnetite produced foliation-defining biotite + epidote + quartz. These reaction products did not replace K-feldspar - hastingsite interfaces; rather, either biotite or epidote replaced the amphibole, and plagioclase replaced K-feldspar. Biotite and epidote precipitated syntectonically in discrete layers that define the foliation in the orthogneiss, whereas quartz precipitated primarily in ribbons, further enhancing the fabric. Metastable REE-rich igneous titanite also dissolved, and was incompletely replaced by REE-poor, Al-bearing metamorphic titanite. The similar concentrations of the REE in epidote and titanite show that the REE released by titanite dissolution were precipitated locally as the allanite component in adjacent grains of epidote. The entire process was syntectonic, with most grains showing multiple overgrowths in the direction of extension as defined by stretched xenoliths. Sufficient U was present in the titanite overgrowths to allow SHRIMP dating of cores, mantles, and rims. These results suggest at least three retrograde Alleghanian events of growth in a span of ???30 m.y. Thus the dissolution - transportation - precipitation process not only describes the reaction mechanism but also leads to the redistribution of reaction products into nearly monomineralic layers, thus contributing to metamorphic differentiation and to the development of the foliation. The resulting orthogneiss was much weaker that the granodiorite protolith, owing to this reaction and textural softening.

REE investigation of the Motru Dyke System components from the Danubian basements (South Carpathians, Romania)

NASA Astrophysics Data System (ADS)

Campeanu, Mara; Balica, Constantin; Balintoni, Ioan; Tănăselia, Claudiu; Cadar, Oana

2017-04-01

Dragsan and Lainici-Paius groups represent the basement components of the Danubian Alpine units (South Carpathians, Romania), which consist of medium-grade metamorphic rocks. A subvolcanic system of dykes (i.e. Motru Dyke System - MDS) crosscut mostly the Lainici Paius basement as an effect of a late-Variscan termo-tectonic event. The geochemical features, frame the MDS components within a wide range of petrotypes (basaltic andesites to rhyolites), and define a wide differentiation series. Classically this subvolcanic system was inferred to be in connection to a unique mantle source [1], however, recent studies [2,3] suggest a mixed mantle-crust source, based on the interpretation of the trace elements in conjunction with Sr and Nd isotope data. Aditionally, the presence of relict zircon grains consolidates this assumption. New REE data collected from eight MDS components, generally confirm the mixed mantle-crust source hypothesis. The distribution patterns reveal two groups of samples. The first group (six samples) is moderately enriched in REE and shows moderately fractionated patterns with (La/Yb)N between 7-21 and low Eu/Eu* (0.81-0.9). The second group, strongly enriched in light REE, have high (La/Yb)N and strong negative Eu anomaly (Eu/Eu* of 0.41 and 0.38 respectively). REE vary between 107-147 ppm for the first group and 612 ppm - 907ppm for the second group. We can assume a stronger fractionation of plagioclase as well as of garnet and amphibole for the second group. With a flatter pattern, for the first group of samples, the fractionation of these minerals appears to be moderate. The emplacement age of MDS has been long disputed, since it was supposed as pre-Silurian for a long time. However, newly zircon U/Pb isotopic dating performed on two collected samples indicate a mean age of 300 My [2,3]. Owing to the croscutting relationships with the post-colisional granitoid plutons emplaced in the Danubian basement during the late Variscan, and based on new geochemical data, we consider that MDS was generated from a mixed mantle and crustal source, and emplaced in a post-collisional tectonic setting during the final stages of the Variscan orogeny. Acknowledgements: study supported by PN-II-ID-PCE-2011-3-0100 Grant, UEFIS-CDI and Core Program - ANCS PN 16.40.02.01. References: [1] Féménias, O., Berza, T., Tatu, M., Diot, H., Demaiffe, D., 2008. Nature and signifiance of a Cambro-Ordovician high-K, calc-alkaline sub-volcanic suite: the late- to post-orogenic Motru Dyke Swarm (Southern Carpathians, Romania), Int. J. Earth Sci. [2] Câmpeanu, M., Balica, C., Balintoni, I.C., 2014. Geochronology and emplacement conditions of Motru Dyke System (South Carpathians, Romania), Bul. Shk. Gjeol.2014- Special Issue, Vol 1/2014, Proceedings of XX CBGA Congress, Tirana, Albania, p.198. [3] Câmpeanu, M., Balica, C., Balintoni, I.C., Tanaselia, C., 2015. Motru Dyke Swarm (South Carpathians, Romania): Emplacement age and geotectonic setting (0) Goldschmidt Abstracts, 2015-459.

Tumoral Versus Flat Intraepithelial Neoplasia of Pancreatobiliary Tract, Gallbladder, and Ampulla of Vater.

PubMed

Jang, Kee-Taek; Ahn, Sangjeong

2016-05-01

-The identification of a precursor lesion is important to understanding the histopathologic and genetic alterations in carcinogenesis. There are a plethora of terminologies that describe precursor lesions of the pancreatobiliary tract, ampulla of Vater, and gallbladder. The current terminologies for precursor lesions may make it difficult to understand the tumor biology. Here, we propose the concept of tumoral and flat intraepithelial neoplasia to improve our understanding of precursor lesions of many epithelial organs, including the pancreatobiliary tract, ampulla of Vater, and gallbladder. -To understand the dichotomous pattern of tumoral and flat intraepithelial neoplasia in carcinogenesis of pancreatobiliary tract, ampulla of Vater, and gallbladder. -Review of relevant literatures indexed in PubMed. -Tumoral intraepithelial neoplasia presents as an intraluminal or intraductal, mass-forming, polypoid lesion or a macroscopic, visible, cystic lesion without intracystic papillae. Microscopically, tumoral intraepithelial neoplasia shows various proportions of papillary and tubular architecture, often with a mixed pattern, such as papillary, tubular, and papillary-tubular. The malignant potential depends on the degree of dysplasia and the cell phenotype of the epithelium. Flat intraepithelial neoplasia presents as a flat or superficial, spreading, mucosal lesion that is frequently accompanied by an invasive carcinoma. Tumoral and flat intraepithelial neoplasias are not homogeneous entities and may exhibit histopathologic spectrum changes and different genetic profiles. Although intraepithelial neoplasia showed a dichotomous pattern in the tumoral versus flat types, they can coexist. Tumoral and flat intraepithelial neoplasia can be interpreted as part of a spectrum of changes in the carcinogenesis pathway of each organ.

Continental crustal composition and lower crustal models

NASA Technical Reports Server (NTRS)

Taylor, S. R.

1983-01-01

The composition of the upper crust is well established as being close to that of granodiorite. The upper crustal composition is reflected in the uniform REE abundances in shales which represent an homogenization of the various REE patterns. This composition can only persist to depths of 10-15 km, for heat flow and geochemical balance reasons. The composition of the total crust is model dependent. One constraint is that it should be capable of generating the upper granodioritic (S.L.) crust by partial melting within the crust. This composition is based on the andesite model, which assumes that the total crust has grown by accretion of island arc material. A representation of the growth rate of the continental crust is shown. The composition of the lower crust, which comprises 60-80% of the continental crust, remains a major unknown factor for models of terrestrial crustal evolution. Two approaches are used to model the lower crust.

Rare earth element transfer from soil to navel orange pulp (Citrus sinensis Osbeck cv. Newhall) and the effects on internal fruit quality.

PubMed

Cheng, Jinjin; Ding, Changfeng; Li, Xiaogang; Zhang, Taolin; Wang, Xingxiang

2015-01-01

The effects of soil rare earth element (REE) on navel orange quality and safety in rare earth ore areas have gained great attention. This study investigated the transfer characteristics of REE from soil to navel orange pulp (Citrus sinensis Osbeck cv. Newhall) and examined the effects of soil REE on internal fruit quality in Xinfeng County, Jiangxi province, China. Path analysis showed that soil REE, pH, cation exchange capacity (CEC), and Fe oxide (Feox) significantly affected pulp REE concentrations. A Freundlich-type prediction model for pulp REE was established: log[REEpulp] = -1.036 + 0.272 log[REEsoil] - 0.056 pH - 0.360 log[CEC] + 0.370 log[Feox] (n = 114, R2 = 0.60). From the prediction model, it was inferred that even when soil REE and Feox were as high as 1038 mg kg-1 and 96.4 g kg-1, respectively, and pH and CEC were as low as 3.75 and 5.08 cmol kg-1, respectively, pulp REE concentrations were much lower than the food limit standard. Additionally, soil REE levels were significantly correlated with selected fruit quality indicators, including titratable acidity (r = 0.52, P < 0.01), total soluble solids (r = 0.48, P < 0.01) and vitamin C (r = 0.56, P < 0.01). Generally, under routine methods of water and fertilization management, the cultivation of navel oranges in rare earth ore areas of south China with soil REE ranging from 38.6 to 546 mg kg-1 had improved in internal fruit quality.

Cracking the Code of Soil Genesis. The Early Role of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Zaharescu, D. G.; Dontsova, K.; Burghelea, C. I.; Maier, R. M.; Huxman, T. E.; Chorover, J.

2014-12-01

Soil is terrestrial life support system. Its genesis involves tight interactions between biota and mineral surfaces that mobilize structural elements into biogeochemical cycles. Of all chemical elements rare earth elements (REE) are a group of 16 non-nutrient elements of unusual geochemical similarity and present in all components of the surface environment. While much is known about the role of major nutrients in soil development we lack vital understanding of how early biotic colonization affects more conservative elements such as REE. A highly controlled experiment was set up at University of Arizona's Biosphere-2 that tested the effect of 4 biological treatments, incorporating a combination of microbe, grass, mycorrhiza and uninoculated control on REE leaching and uptake in 4 bedrock substrates: basalt, rhyolite, granite and schist. Generally the response of REE to biota presence was synergistic. Variation in total bedrock chemistry could explain major trends in pore water REE. There was a fast transition from chemistry-dominated to a biota dominated environment in the first 3-4 months of inoculation/seeding which translated into increase in REE signal over time. Relative REE abundances in water were generally reflected in plant concentrations, particularly in root, implying that below ground biomass is the main sync of REE in the ecosystem. Mycorrhiza effect on REE uptake in plant organs was significant and increased with infection rates. Presence of different biota translated into subtle differences in REE release, reveling potential biosignatures of biolota-rock colonization. The results thus bring fundamental insight into early stages non-nutrient cycle and soil genesis.

Toxic effects of environmental rare earth elements on delayed outward potassium channels and their mechanisms from a microscopic perspective.

PubMed

Wang, Lihong; He, Jingfang; Xia, Ao; Cheng, Mengzhu; Yang, Qing; Du, Chunlei; Wei, Haiyan; Huang, Xiaohua; Zhou, Qing

2017-08-01

The wide applications cause a large amount of rare earth elements (REEs) to be released into the environment, and ultimately into the human body through food chain. Toxic effects of REEs on humans have been extensively studied, but their toxic effects and binding targets in cells are not understood. Delayed outward potassium channels (K + channels) are good targets for exogenous substances or clinical drugs. To evaluate cellular toxicities of REEs and clarify toxic mechanisms, the toxicities of REEs on the K + channel and their structural basis were investigated. The results showed that delayed outward potassium channels on the plasma membrane are the targets of REEs acting on living organisms, and the changes in the thermodynamic and kinetic characteristics of the K + channel are the reasons of diseases induced by REEs. Two types of REEs, a light REE La 3+ and a heavy REE Tb 3+ , displayed different intensity of toxicities on the K + channel, in which the toxicity of Tb 3+ was stronger than that of La 3+ . More interestingly, in comparison with that of heavy metal Cd 2+ , the cytotoxicities of the light and heavy REEs showed discriminative differences, and the cytotoxicity of Tb 3+ was higher than that of Cd 2+ , while the cytotoxicity of La 3+ was lower than that of Cd 2+ . These different cytotoxicities of La 3+ , Tb 3+ and Cd 2+ on human resulted from the varying binding abilities of the metals to this channel protein. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rare Earth Element Transfer from Soil to Navel Orange Pulp (Citrus sinensis Osbeck cv. Newhall) and the Effects on Internal Fruit Quality

PubMed Central

Cheng, Jinjin; Ding, Changfeng; Li, Xiaogang; Zhang, Taolin; Wang, Xingxiang

2015-01-01

The effects of soil rare earth element (REE) on navel orange quality and safety in rare earth ore areas have gained great attention. This study investigated the transfer characteristics of REE from soil to navel orange pulp (Citrus sinensis Osbeck cv. Newhall) and examined the effects of soil REE on internal fruit quality in Xinfeng County, Jiangxi province, China. Path analysis showed that soil REE, pH, cation exchange capacity (CEC), and Fe oxide (Feox) significantly affected pulp REE concentrations. A Freundlich-type prediction model for pulp REE was established: log[REEpulp] = -1.036 + 0.272 log[REEsoil] - 0.056 pH - 0.360 log[CEC] + 0.370 log[Feox] (n = 114, R2 = 0.60). From the prediction model, it was inferred that even when soil REE and Feox were as high as 1038 mg kg-1 and 96.4 g kg-1, respectively, and pH and CEC were as low as 3.75 and 5.08 cmol kg-1, respectively, pulp REE concentrations were much lower than the food limit standard. Additionally, soil REE levels were significantly correlated with selected fruit quality indicators, including titratable acidity (r = 0.52, P < 0.01), total soluble solids (r = 0.48, P < 0.01) and vitamin C (r = 0.56, P < 0.01). Generally, under routine methods of water and fertilization management, the cultivation of navel oranges in rare earth ore areas of south China with soil REE ranging from 38.6 to 546 mg kg-1 had improved in internal fruit quality. PMID:25806821

Rare earth element partitioning between hydrous ferric oxides and acid mine water during iron oxidation

USGS Publications Warehouse

Verplanck, P.L.; Nordstrom, D. Kirk; Taylor, Howard E.; Kimball, B.A.

2004-01-01

Ferrous iron rapidly oxidizes to Fe (III) and precipitates as hydrous Fe (III) oxides in acid mine waters. This study examines the effect of Fe precipitation on the rare earth element (REE) geochemistry of acid mine waters to determine the pH range over which REEs behave conservatively and the range over which attenuation and fractionation occur. Two field studies were designed to investigate REE attenuation during Fe oxidation in acidic, alpine surface waters. To complement these field studies, a suite of six acid mine waters with a pH range from 1.6 to 6.1 were collected and allowed to oxidize in the laboratory at ambient conditions to determine the partitioning of REEs during Fe oxidation and precipitation. Results from field experiments document that even with substantial Fe oxidation, the REEs remain dissolved in acid, sulfate waters with pH below 5.1. Between pH 5.1 and 6.6 the REEs partitioned to the solid phases in the water column, and heavy REEs were preferentially removed compared to light REEs. Laboratory experiments corroborated field data with the most solid-phase partitioning occurring in the waters with the highest pH. ?? 2004 Elsevier Ltd. All rights reserved.

Changes in energy expenditure in preterm infants during weaning: a randomized comparison of two weaning methods from an incubator.

PubMed

Weintraub, Valentin; Mimouni, Francis B; Dollberg, Shaul

2007-03-01

We aimed to compare resting energy expenditure (REE) of infants exposed to either one of two weaning methods and to confirm the increase in REE during weaning from incubator. The study was a prospective randomized clinical trial of weaning preterm infants using either of two methods. REE was measured at baseline and 6, 23, 30, and 47 h, using indirect calorimetry. At measurement, infants were clinically and thermally stable, asleep, 2 h after feeding. Forty-two patients were randomized to "open incubator" (n = 23) or "warming bassinet" (n = 19). The groups did not differ in baseline clinical characteristics. REE increased significantly in both groups within 23 h, and remained stable at 30 and 47 h. At 6 and 23 h, the incubator group had significantly higher increase in REE than the warming bassinet group. By 30 h and at 47 h post-weaning, the REE of both groups became similar. In conclusion, REE increases significantly at weaning from incubator. The warming bassinet delays the increase in REE observed when infants are weaned using a turned off incubator. Whether one method is superior to the other in terms of thermic stress cannot be determined from this study.

The Crystal-Chemical Effect of REE Separation in Minerals: Causes and Practical Values

NASA Astrophysics Data System (ADS)

Vinokurov, S. F.

2018-03-01

Contrast variations in the type of REE distribution from a distinctly negative mode to a positive mode is revealed in zonal fluorites of Eastern Transbaikal, with a pronounced decrease in the Ce/Y ratios in successive zones of increasing Y accompanied by a gradual decrease in the temperature and salinity of fluid inclusions in the fluorites. It is assumed that these facts are caused by the appearance of nm-size phases of REE minerals characterized by various crystalline structures and demonstrating selective concentrations of lanthanides, i.e., exhibiting a crystal-chemical differentiation of REEs that is widespread in the processes of mineral formation. Based on this natural mechanism, the development of a procedure of selective REE extraction from the concentrates is proposed. The primary laboratory experiments resulted in the discovery of the difference in REE concentrations in the sediment and filtrate with the separation coefficient varying by a factor of 76. The results obtained allow one to expect a true separation possibility for Nd along with the medium and heavy REEs. In view of the data obtained, the crystalline-chemical separation of REEs has some advantages compared to the processes currently used, especially extraction.

Ridge Minimization of Ablated Morphologies on ITO Thin Films Using Squared Quasi-Flat Top Beam

PubMed Central

Jeon, Jin-Woo; Choi, Wonsuk; Shin, Young-Gwan; Ji, Suk-Young

2018-01-01

In this study, we explore the improvements in pattern quality that was obtained with a femtosecond laser with quasi-flat top beam profiles at the ablated edge of indium tin oxide (ITO) thin films for the patterning of optoelectronic devices. To ablate the ITO thin films, a femtosecond laser is used that has a wavelength and pulse duration of 1030 nm and 190 fs, respectively. The squared quasi-flat top beam is obtained from a circular Gaussian beam using slits with varying x-y axes. Then, the patterned ITO thin films are measured using both scanning electron and atomic force microscopes. In the case of the Gaussian beam, the ridge height and width are approximately 39 nm and 1.1 μm, respectively, whereas, when the quasi-flat top beam is used, the ridge height and width are approximately 7 nm and 0.25 μm, respectively. PMID:29601515

MICROBIALLY MEDIATED LEACHING OF RARE EARTH ELEMENTS FROM RECYCLABLE MATERIALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, D. W.; Fujita, Y.; Daubaras, D. L.

2016-09-01

Bioleaching offers a potential approach for recovery of rare earth elements (REE) from recyclable materials, such as fluorescent lamp phosphors or degraded industrial catalysts. Microorganisms were enriched from REE-containing ores and recyclable materials with the goal of identifying strains capable of extracting REE from solid materials. Over 100 heterotrophic microorganisms were isolated and screened for their ability to produce organic acids capable of leaching REE. The ten most promising isolates were most closely related to Pseudomonas, Acinetobacter and Talaromyces. Of the acids produced, gluconic acid appeared to be the most effective at leaching REE (yttrium, lanthanum, cerium, europium, and terbium)more » from retorted phosphor powders (RPP), fluidized cracking catalyst (FCC), and europium-doped yttrium oxide (YOEu). We found that an Acinetobacter isolates, BH1, was the most capable strain and able to leach 33% of the total REE content from the FCC material. These results support the continuing evaluation of gluconic acid-producing microbes for large-scale REE recovery from recyclable materials.« less

Novel approach in k0-NAA for highly concentrated REE Samples.

PubMed

Abdollahi Neisiani, M; Latifi, M; Chaouki, J; Chilian, C

2018-04-01

The present paper presents a new approach for k 0 -NAA for accurate quantification with short turnaround analysis times for rare earth elements (REEs) in high content mineral matrices. REE k 0 and Q 0 values, spectral interferences and nuclear interferences were experimentally evaluated and improved with Alfa Aesar Specpure Plasma Standard 1000mgkg -1 mono-rare earth solutions. The new iterative gamma-ray self-attenuation and neutron self-shielding methods were investigated with powder standards prepared from 100mg of 99.9% Alfa Aesar mono rare earth oxide diluted with silica oxide. The overall performance of the new k 0 -NAA method for REEs was validated using a certified reference material (CRM) from Canadian Certified Reference Materials Project (REE-2) with REE content ranging from 7.2mgkg -1 for Yb to 9610mgkg -1 for Ce. The REE concentration was determined with uncertainty below 7% (at 95% confidence level) and proved good consistency with the CRM certified concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

Photographic diabetic retinopathy screening in an urban family practice clinic: effect on compliance to eye examination.

PubMed

Shah, Sanket U; Seibles, JoAnn; Park, Susanna S

2011-01-01

This study assessed the effect of introduction of diabetic retinopathy screening using non-mydriatic digital fundus photography (nDFP) in an urban academic family practice clinic on patient compliance to recommended dilated eye examination (REE). Two hundred four patients with diabetes mellitis who were noncompliant to annual REE were screened for diabetic retinopathy using nDFP. The images were electronically transmitted to the retinal specialist to triage them for follow-up REE based on the photographic findings. Retrospective review of their medical records compared the compliance to REE before and after nDFP screening. Compliance to REE increased from 9% before screening to 66.5% after screening (P < .0001). Good quality fundus images were obtained in 93% of the eyes. Introduction of nDFP for diabetic retinopathy screening in the family practice clinic can result in a dramatic increase in compliance to REE among patients with diabetes mellitis previously poorly compliant to REE. Copyright 2011, SLACK Incorporated.

High resolution rare-earth elements analyses of natural apatite and its application in geo-sciences: Combined micro-PIXE, quantitative CL spectroscopy and electron spin resonance analyses

NASA Astrophysics Data System (ADS)

Habermann, D.; Götte, T.; Meijer, J.; Stephan, A.; Richter, D. K.; Niklas, J. R.

2000-03-01

The rare-earth element (REE) distribution in natural apatite is analysed by micro-PIXE, cathodoluminescence (CL) microscopy and spectroscopy and electron spin resonance (ESR) spectroscopy. The micro-PIXE analyses of an apatite crystal from Cerro de Mercado (Mexico) and the summary of 20 analyses of six francolite (conodonts of Triassic age) samples indicate that most of the REEs are enriched in apatite and francolite comparative to average shale standard (NASC). The analyses of fossil francolite revealing the REE-distribution not to be in balance with the REE-distribution of seawater and fish bone debris. Strong inhomogenous lateral REE-distribution in fossil conodont material is shown by CL-mapping and most probably not being a vital effect. Therefore, the resulting REE-signal from fossil francolite is the sum of vital and post-mortem incorporation. The necessary charge compensation for the substitution of divalent Ca by trivalent REE being done by different kind of electron defects and defect ions.

The Ellsworth terrane, coastal Maine: Geochronology, geochemistry, and Nd-Pb isotopic composition - Implications for the rifting of Ganderia

USGS Publications Warehouse

Schulz, K.J.; Stewart, D.B.; Tucker, R.D.; Pollock, J.C.; Ayuso, R.A.

2008-01-01

The Ellsworth terrane is one of a number of fault-bounded blocks that occur along the eastern margin of Ganderia, the western-most of the peri-Gondwanan domains in the northern Appalachians that were accreted to Laurentia in the Paleozoic. Geologic relations, detrital zircon ages, and basalt geochemistry suggest that the Ellsworth terrane is part of Ganderia and not an exotic terrane. In the Penobscot Bay area of coastal Maine, the Ellsworth terrane is dominantly composed of bimodal basalt-rhyolite volcanic sequences of the Ellsworth Schist and unconformably overlying Castine Volcanics. We use new U-Pb zircon geochronology, geochemistry, and Nd and Pb isotopes for these volcanic sequences to constrain the petrogenetic history and paleotectonic setting of the Ellsworth terrane and its relationship with Ganderia. U-Pb zircon geochronology for rhyolites indicates that both the Ellsworth Schist (508.6 ?? 0.8 Ma) and overlying Castine Volcanics (503.5 ?? 2.5 Ma) are Middle Cambrian in age. Two tholefitic basalt types are recognized. Type Tb-1 basalt, present as pillowed and massive lava flows and as sills in both units, has depleted La and Ce ([La/Nd]N = 0.53-0.87) values, flat heavy rare earth element (REE) values, and no positive Th or negative Ta anomalies on primitive mantle-normalized diagrams. In contrast, type Th-2 basalt, present only in the Castine Volcanics, has stightly enriched LREE ([La/Yb]N = 1.42-2.92) values and no Th or Th anomalies. Both basalt types have strongly positive ??Nd (500) values (Th-1 = +7.9-+8.6; Th-2 = +5.6-+7.0) and relatively enriched Pb isotopic compositions (206Ph/204Pb = 18.037-19.784; 207/204Pb = 15.531-15.660; 2088Pb/204Pb = 37.810-38.817). The basalts have compositions transitional between recent normal and enriched mid-ocean-ridge basalt, and they were probably derived by partial melting of compositionatly heterogeneous asthenosphenc mantle. Two types of rhyolite also are present. Type R-1 rhyolite, which mostly occurs as tuffs interlayered with basalt in the Ellsworth Schist, is calc-alkaline and characterized by relatively low REE, Zr, and Hf contents, enriched LREE ([La/Yb]N ???3-6), positive Th and negative Th anomalies, ??Nd (500) values near zero (+0.5 to -0.9), and relatively unradiogenic Ph isotope values (206Pb/204Pb = 18.845; 207Pb/ 204Pb = 15.625; 208Pb/204Pb = 38.626). The data suggest that R-1 rhyolite magma was Likely derived by mixing of basalt with melts from a relatively depleted crustal source. Type R-2 rhyolite, which mostly occurs as lava flows and domes in the Castine volcanics, is tholeiitic and characterized by enriched REE with flat patterns ([La/Yb]N = 1-2.5), moderate negative Eu anomalies (Eu/Eu* = 0-34.5), enriched Th, small negative Th anomalies, and ??Nd (500) (+5.8-+7.5) and Ph isotope (206Pb/204Pb = 19.175-19.619; 207Pb/204Pb = 15.605--15.649; 208Pb/204Pb = 38.834-38.851) values that overlap those of the tholeiitic basalts. The data suggest that R-2 rhyolite magma was derived by the partial melting of hydrothermally altered basalt with the addition of a small amount of an enriched component, probably R-1 rhyolite. The geololic, geochemicai, and isotopic characteristics of the bimodal volcanic sequences strongly suggest that the Ellsworth terrane did not evolve as an extensional back-arc basin behind an active arc, but rather it evolved as a proto-oceanic rift petrogenetically similar to Cenozoic rifts like the Gulf of California-Salton mrough and Red Sea-Gulf of Aden rift systems. Such a setting is supported by the presence of serpentinized mantle and zinc-copper-rich massive sulfide deposits in the Ellsworth terrane. We conclude that the Ellsworth terrane developed as a Mid

Sources of Extraterrestrial Rare Earth Elements:To the Moon and Beyond

NASA Astrophysics Data System (ADS)

McLeod, C. L.; Krekeler, M. P. S.

2017-08-01

The resource budget of Earth is limited. Rare-earth elements (REEs) are used across the world by society on a daily basis yet several of these elements have <2500 years of reserves left, based on current demand, mining operations, and technologies. With an increasing population, exploration of potential extraterrestrial REE resources is inevitable, with the Earth's Moon being a logical first target. Following lunar differentiation at 4.50-4.45 Ga, a late-stage (after 99% solidification) residual liquid enriched in Potassium (K), Rare-earth elements (REE), and Phosphorus (P), (or "KREEP") formed. Today, the KREEP-rich region underlies the Oceanus Procellarum and Imbrium Basin region on the lunar near-side (the Procellarum KREEP Terrain, PKT) and has been tentatively estimated at preserving 2.2 × 10^8 km^3 of KREEP-rich lithologies. The majority of lunar samples (Apollo, Luna, or meteoritic samples) contain REE-bearing minerals as trace phases, e.g., apatite and/or merrillite, with merrillite potentially contributing up to 3% of the PKT. Other lunar REE-bearing lunar phases include monazite, yittrobetafite (up to 94,500 ppm yttrium), and tranquillityite (up to 4.6 wt % yttrium, up to 0.25 wt % neodymium), however, lunar sample REE abundances are low compared to terrestrial ores. At present, there is no geological, mineralogical, or chemical evidence to support REEs being present on the Moon in concentrations that would permit their classification as ores. However, the PKT region has not yet been mapped at high resolution, and certainly has the potential to yield higher REE concentrations at local scales (<10s of kms). Future lunar exploration and mapping efforts may therefore reveal new REE deposits. Beyond the Moon, Mars and other extraterrestrial materials are host to REEs in apatite, chevkinite-perrierite, merrillite, whitlockite, and xenotime. These phases are relatively minor components of the meteorites studied to date, constituting <0.6% of the total sample. Nonetheless, they dominate a samples REE budget with their abundances typically 1-2 orders of magnitude enriched relative to their host rock. As with the Moon, though phases which host REEs have been identified, no extraterrestrial REE resource, or ore, has been identified yet. At present extraterrestrial materials are therefore not suitable REE-mining targets. However, they are host to other resources that will likely be fundamental to the future of space exploration and support the development of in situ resource utilization, for example: metals (Fe, Al, Mg, PGEs) and water.

Trace element abundances of high-MgO glasses from Kilauea, Mauna Loa and Haleakala volcanoes, Hawaii

USGS Publications Warehouse

Wagner, T.P.; Clague, D.A.; Hauri, E.H.; Grove, T.L.

1998-01-01

We performed an ion-microprobe study of eleven high-MgO (6.7-14.8 wt%) tholeiite glasses from the Hawaiian volcanoes Kilauea, Mauna Loa and Haleakala. We determined the rare earth (RE), high field strength, and other selected trace element abundances of these glasses, and used the data to establish their relationship to typical Hawaiian shield tholeiite and to infer characteristics of their source. The glasses have trace element abundance characteristics generally similar to those of typical shield tholeiites, e.g. L(light)REE/H(heavy)REE(C1) > 1. The Kilauea and Mauna Loa glasses, however, display trace and major element characteristics that cross geochemical discriminants observed between Kilauea and Mauna Loa shield lavas. The glasses contain a blend of these discriminating chemical characteristics, and are not exactly like the typical shield lavas from either volcano. The production of these hybrid magmas likely requires a complexly zoned source, rather than two unique sources. When corrected for olivine fractionation, the glass data show correlations between CaO concentration and incompatible trace element abundances, indicating that CaO may behave incompatibly during melting of the tholeiite source. Furthermore, the tholeiite source must contain residual garnet and clinopyroxene to account for the variation in trace element abundances of the Kilauea glasses. Inversion modeling indicates that the Kilauea source is flat relative to C1 chondrites, and has a higher bulk distribution coefficient for the HREE than the LREE.

Issues in characterizing resting energy expenditure in obesity and after weight loss

PubMed Central

Bosy-Westphal, Anja; Braun, Wiebke; Schautz, Britta; Müller, Manfred J.

2013-01-01

Limitations of current methods: Normalization of resting energy expenditure (REE) for body composition using the 2-compartment model fat mass (FM), and fat-free mass (FFM) has inherent limitations for the interpretation of REE and may lead to erroneous conclusions when comparing people with a wide range of adiposity as well as before and after substantial weight loss. Experimental objectives: We compared different methods of REE normalization: (1) for FFM and FM (2) by the inclusion of %FM as a measure of adiposity and (3) based on organ and tissue masses. Results were compared between healthy subjects with different degrees of adiposity as well as within subject before and after weight loss. Results: Normalizing REE from an “REE vs. FFM and FM equation” that (1) was derived in obese participants and applied to lean people or (2) was derived before weight loss and applied after weight loss leads to the erroneous conclusion of a lower metabolic rate (i) in lean persons and (ii) after weight loss. This is revealed by the normalization of REE for organ and tissue masses that was not significantly different between lean and obese or between baseline and after weight loss. There is evidence for an increasing specific metabolic rate of FFM with increasing %FM that could be explained by a higher contribution of liver, kidney and heart mass to FFM in obesity. Using “REE vs. FFM and FM equations” specific for different levels of adiposity (%FM) eliminated differences in REE before and after weight loss in women. Conclusion: The most established method for normalization of REE based on FFM and FM may lead to spurious conclusions about metabolic rate in obesity and the phenomenon of weight loss-associated adaptive thermogenesis. Using %FM-specific REE prediction from FFM and FM in kg may improve the normalization of REE when subjects with wide differences in %FM are investigated. PMID:23532370

Leaching behavior of rare earth elements in fort union lignite coals of North America

DOE PAGES

Laudal, Daniel A.; Benson, Steven A.; Addleman, Raymond Shane; ...

2018-03-30

Fort Union lignite coal samples were subjected to a series of aqueous leaching experiments to understand the extraction behavior of the rare earth elements (REE). This testing was aimed at understanding the modes of occurrence of the REE in the lignite coals, as well as to provide foundational data for development of rare earth extraction processes. In a first series of tests, a sequential leaching process was used to investigate modes of occurrence of the REE of select lignite coals. The tests involved sequential exposure to solvents consisting of water, ammonium acetate and dilute hydrochloric acid (HCl). The results indicatedmore » that water and ammonium acetate extracted very little of the REE, indicating the REE are not present as water soluble or ion-exchangeable forms. However, the data shows that a large percentage of the REE were extracted with the hydrochloric acid (80–95 wt%), suggesting presence in HCl-soluble mineral forms such as carbonates, and/or presence as organic complexes. A second series of tests was performed involving single-step leaching with dilute acids and various operating parameters, including acid type, acid concentration, acid/coal contact time and coal particle size. For select samples, additional tests were performed to understand the results of leaching, including float-sink density separations and humic acid extraction. The results have shown that the majority of REE in Fort Union lignites appear to be associated weakly with the organic matrix of the coals, most likely as coordination complexes of carboxylic acid groups. The light REE and heavy REE exhibit different behaviors, however. The extractable light REE appear to have association both in acid-soluble mineral forms and as organic complexes, whereas the extractable heavy REE appear to be almost solely associated with the organics. In conclusion, scandium behavior was notably different than yttrium and the lanthanides, and the data suggests the extractable content is primarily associated as acid-soluble mineral forms.« less

Energy prediction equations are inadequate for obese Hispanic youth.

PubMed

Klein, Catherine J; Villavicencio, Stephan A; Schweitzer, Amy; Bethepu, Joel S; Hoffman, Heather J; Mirza, Nazrat M

2011-08-01

Assessing energy requirements is a fundamental activity in clinical dietetics practice. A study was designed to determine whether published linear regression equations were accurate for predicting resting energy expenditure (REE) in fasted Hispanic children with obesity (aged 7 to 15 years). REE was measured using indirect calorimetry; body composition was estimated with whole-body air displacement plethysmography. REE was predicted using four equations: Institute of Medicine for healthy-weight children (IOM-HW), IOM for overweight and obese children (IOM-OS), Harris-Benedict, and Schofield. Accuracy of the prediction was calculated as the absolute value of the difference between the measured and predicted REE divided by the measured REE, expressed as a percentage. Predicted values within 85% to 115% of measured were defined as accurate. Participants (n=58; 53% boys) were mean age 11.8±2.1 years, had 43.5%±5.1% body fat, and had a body mass index of 31.5±5.8 (98.6±1.1 body mass index percentile). Measured REE was 2,339±680 kcal/day; predicted REE was 1,815±401 kcal/day (IOM-HW), 1,794±311 kcal/day (IOM-OS), 1,151±300 kcal/day (Harris-Benedict), and, 1,771±316 kcal/day (Schofield). Measured REE adjusted for body weight averaged 32.0±8.4 kcal/kg/day (95% confidence interval 29.8 to 34.2). Published equations predicted REE within 15% accuracy for only 36% to 40% of 58 participants, except for Harris-Benedict, which did not achieve accuracy for any participant. The most frequently accurate values were obtained using IOM-HW, which predicted REE within 15% accuracy for 55% (17/31) of boys. Published equations did not accurately predict REE for youth in the study sample. Further studies are warranted to formulate accurate energy prediction equations for this population. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

Geochemistry of REE in Acid Mine Drainage: Sorption onto Basaluminite and Schwertmannite.

NASA Astrophysics Data System (ADS)

Lozano Letellier, A.; Ayora, C.; Fernandez-Martinez, A.

2017-12-01

The geochemistry of Rare Earth Elements (REE) has been investigated in natural streams and in mine areas during the last decades. Most of these studies agree that REE are mobile in acidic waters and they transferred to a solid phase when pH increases. However, there is no agreement on the pH range, on which precipitates can retain REE and the mechanisms responsible for the retention. Thus, whereas some authors determined that hydrous ferric oxides (HFOs) scavenge REE from pH 3, other authors observed REE retention by hydrous aluminum oxides (HAOs) from pH 4 to 6.1. A field survey conducted in the Odiel River in the SW Spain showed that pH values higher than 5, REE, Cu, Al and Fe concentrations in the river were lower than expected from a theoretical mixture because they were trapped in the precipitates. For pH below 4, however, only schwertmannite (Fe8O8OH6SO4) and no basaluminite (Al4SO4OH10·5H2O) precipitated. Then, REE, Cu and Al behaved conservatively and Fe does not, indicating that REE are trapped in the Al but not in the Fe solid phase. These observations are perfectly consistent with the REE accumulation in the Al-rich precipitates in the AMD treatment systems. Taking into account these observations, sorption experiments with synthetic basaluminite and schwertmannite at different pH were performed in the laboratory. For Lanthanides and Yttrium, sorption edge took place at pH higher than 5, whereas Sc sorption started at pH 4. A surface complexation model is proposed to explain the retention mechanism onto these two precipitates. Both minerals, schwertmannite and basaluminite showed similar sorption behavior. However, as schwertmannite formation occurs at pH lower than 4, no REE elements are sorbed on it.

Leaching behavior of rare earth elements in fort union lignite coals of North America

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laudal, Daniel A.; Benson, Steven A.; Addleman, Raymond Shane

Fort Union lignite coal samples were subjected to a series of aqueous leaching experiments to understand the extraction behavior of the rare earth elements (REE). This testing was aimed at understanding the modes of occurrence of the REE in the lignite coals, as well as to provide foundational data for development of rare earth extraction processes. In a first series of tests, a sequential leaching process was used to investigate modes of occurrence of the REE of select lignite coals. The tests involved sequential exposure to solvents consisting of water, ammonium acetate and dilute hydrochloric acid (HCl). The results indicatedmore » that water and ammonium acetate extracted very little of the REE, indicating the REE are not present as water soluble or ion-exchangeable forms. However, the data shows that a large percentage of the REE were extracted with the hydrochloric acid (80–95 wt%), suggesting presence in HCl-soluble mineral forms such as carbonates, and/or presence as organic complexes. A second series of tests was performed involving single-step leaching with dilute acids and various operating parameters, including acid type, acid concentration, acid/coal contact time and coal particle size. For select samples, additional tests were performed to understand the results of leaching, including float-sink density separations and humic acid extraction. The results have shown that the majority of REE in Fort Union lignites appear to be associated weakly with the organic matrix of the coals, most likely as coordination complexes of carboxylic acid groups. The light REE and heavy REE exhibit different behaviors, however. The extractable light REE appear to have association both in acid-soluble mineral forms and as organic complexes, whereas the extractable heavy REE appear to be almost solely associated with the organics. In conclusion, scandium behavior was notably different than yttrium and the lanthanides, and the data suggests the extractable content is primarily associated as acid-soluble mineral forms.« less

Automated Quantitative Rare Earth Elements Mineralogy by Scanning Electron Microscopy

NASA Astrophysics Data System (ADS)

Sindern, Sven; Meyer, F. Michael

2016-09-01

Increasing industrial demand of rare earth elements (REEs) stems from the central role they play for advanced technologies and the accelerating move away from carbon-based fuels. However, REE production is often hampered by the chemical, mineralogical as well as textural complexity of the ores with a need for better understanding of their salient properties. This is not only essential for in-depth genetic interpretations but also for a robust assessment of ore quality and economic viability. The design of energy and cost-efficient processing of REE ores depends heavily on information about REE element deportment that can be made available employing automated quantitative process mineralogy. Quantitative mineralogy assigns numeric values to compositional and textural properties of mineral matter. Scanning electron microscopy (SEM) combined with a suitable software package for acquisition of backscatter electron and X-ray signals, phase assignment and image analysis is one of the most efficient tools for quantitative mineralogy. The four different SEM-based automated quantitative mineralogy systems, i.e. FEI QEMSCAN and MLA, Tescan TIMA and Zeiss Mineralogic Mining, which are commercially available, are briefly characterized. Using examples of quantitative REE mineralogy, this chapter illustrates capabilities and limitations of automated SEM-based systems. Chemical variability of REE minerals and analytical uncertainty can reduce performance of phase assignment. This is shown for the REE phases parisite and synchysite. In another example from a monazite REE deposit, the quantitative mineralogical parameters surface roughness and mineral association derived from image analysis are applied for automated discrimination of apatite formed in a breakdown reaction of monazite and apatite formed by metamorphism prior to monazite breakdown. SEM-based automated mineralogy fulfils all requirements for characterization of complex unconventional REE ores that will become increasingly important for supply of REEs in the future.

Modification of REE distribution of ordinary chondrites from Atacama (Chile) and Lut (Iran) hot deserts: Insights into the chemical weathering of meteorites

NASA Astrophysics Data System (ADS)

Pourkhorsandi, Hamed; D'Orazio, Massimo; Rochette, Pierre; Valenzuela, Millarca; Gattacceca, Jérôme; Mirnejad, Hassan; Sutter, Brad; Hutzler, Aurore; Aboulahris, Maria

2017-09-01

The behavior of rare earth elements (REEs) during hot desert weathering of meteorites is investigated. Ordinary chondrites (OCs) from Atacama (Chile) and Lut (Iran) deserts show different variations in REE composition during this process. Inductively coupled plasma-mass spectrometry (ICP-MS) data reveal that hot desert OCs tend to show elevated light REE concentrations, relative to OC falls. Chondrites from Atacama are by far the most enriched in REEs and this enrichment is not necessarily related to their degree of weathering. Positive Ce anomaly of fresh chondrites from Atacama and the successive formation of a negative Ce anomaly with the addition of trivalent REEs are similar to the process reported from Antarctic eucrites. In addition to REEs, Sr and Ba also show different concentrations when comparing OCs from different hot deserts. The stability of Atacama surfaces and the associated old terrestrial ages of meteorites from this region give the samples the necessary time to interact with the terrestrial environment and to be chemically modified. Higher REE contents and LREE-enriched composition are evidence of contamination by terrestrial soil. Despite their low degrees of weathering, special care must be taken into account while working on the REE composition of Atacama meteorites for cosmochemistry applications. In contrast, chondrites from the Lut desert show lower degrees of REE modification, despite significant weathering signed by Sr content. This is explained by the relatively rapid weathering rate of the meteorites occurring in the Lut desert, which hampers the penetration of terrestrial material by forming voluminous Fe oxide/oxyhydroxides shortly after the meteorite fall.

Resting energy expenditure changes with weight loss: racial differences.

PubMed

Wang, Xuewen; You, Tongjian; Lenchik, Leon; Nicklas, Barbara J

2010-01-01

It is controversial whether weight loss reduces resting energy expenditure (REE) to a different magnitude in black and white women. This aim of this study was to determine whether changes in REE with weight loss were different between black and white postmenopausal women, and whether changes in body composition (including regional lean and fat mass) were associated with REE changes within each race. Black (n = 26) and white (n = 65) women (age = 58.2 +/- 5.4 years, 25 < BMI < 40 kg/m(2)) completed a 20-week weight-loss intervention. Body weight, lean and fat mass (total body, limb, and trunk) via dual-energy X-ray absorptiometry, and REE via indirect calorimetry were measured before and after the intervention. We found that baseline REE positively correlated with body weight, lean and fat mass (total, limb, and trunk) in white women only (P < 0.05 for all). The intervention decreased absolute REE in both races similarly (1,279 +/- 162 to 1,204 +/- 169 kcal/day in blacks; 1,315 +/- 200 to 1,209 +/- 185 kcal/day in whites). REE remained decreased after adjusting for changes in total or limb lean mass in black (1,302-1,182 kcal/day, P = 0.043; 1,298-1,144 kcal/day, P = 0.006, respectively), but not in white, women. Changes in REE correlated with changes in body weight (partial r = 0.277) and fat mass (partial r = 0.295, 0.275, and 0.254 for total, limb, and trunk, respectively; P < 0.05) independent of baseline REE in white women. Therefore, with weight loss, REE decreased in proportion to the amount of fat and lean mass lost in white, but not black, women.

Effect of some light rare earth elements on seed germination, seedling growth and antioxidant metabolism in Triticum durum.

PubMed

d'Aquino, Luigi; de Pinto, Maria Concetta; Nardi, Luca; Morgana, Massimo; Tommasi, Franca

2009-05-01

Rare earth elements (REEs) enriched fertilizers have been commonly used in China since the 1980s, thus inducing a growing concern about their environmental impact in agriculture. In this work, the effect of some light REEs nitrate mixture and La(3+) nitrate on seed germination, seedling growth and antioxidant metabolism in Triticum durum was investigated with the aim of clarifying the potential benefits or damages of REEs on plants. Seed pre-soaking for 8 h with La(3+) and REEs nitrate inhibited seed germination at low concentrations (0.01 mM and 0.1 mM), while pre-soaking for 2 and 4 h already inhibited seed germination when higher concentrations (1 mM and 10 mM) of La(3+) and REEs nitrate were used. La(3+) and REEs nitrate treatment also affected seedling growth. Root growth was enhanced and inhibited at low and high concentrations, respectively. Shoot growth was inhibited by La(3+) and REEs nitrate at all tested concentrations after 12 d of treatments. Enzymatic and non enzymatic antioxidants were differently affected by La(3+) and REEs nitrate and their behaviour changed also depending on the plant organ. In roots La(3+) and REEs nitrate treatments induced an increase in ascorbate (ASC) and glutathione (GSH) contents. In shoots only La(3+) nitrate induced an increase in the ASC content whereas GSH decreased following both La(3+) and REEs nitrate treatments. An increase in ASC peroxidase activity was observed in shoots and roots, while catalase did not change in roots and slightly decreased in shoots. The possible role of the increase in some antioxidants as indicators of stress caused by lanthanide treatments is discussed.

Comparison of the partitioning behaviours of yttrium, rare earth elements, and titanium between hydrogenetic marine ferromanganese crusts and seawater

USGS Publications Warehouse

Bau, M.; Koschinsky, A.; Dulski, P.; Hein, J.R.

1996-01-01

In order to evaluate details of the partitioning behaviours of Y, rare earth elements (REEs), and Ti between inorganic metal oxide surfaces and seawater, we studied the distribution of these elements in hydrogenetic marine ferromanganese (Fe-Mn) crusts from the Central Pacific Ocean. Nonphosphatized Fe-Mn crusts display shale-normalized rare earths and yttrium (REYSN) patterns (Y inserted between Dy and Ho) that are depleted in light REEs (LREEs) and which show negative anomalies for YSN, and positive anomalies for LaSN, EuSN, GdSN, and in most cases, CeSN. They show considerably smaller Y/ Ho ratios than seawater or common igneous and clastic rocks, indicating that Y and Ho are fractionated in the marine environment. Compared to P-poor crusts, REYSN patterns of phosphatized Fe-Mn crusts are similar, but yield pronounced positive YSN anomalies, stronger positive LaSN anomalies, and enrichment of the HREEs relative to the MREEs. The data suggest modification of REY during phosphatization and indicate that studies requiring primary REY distributions or isotopic ratios should be restricted to nonphosphatized (layers of) Fe-Mn crusts. Apparent bulk coefficients, KMD, describing trace metal partitioning between nonphosphatized hydrogenetic Fe-Mn crusts and seawater, are similar for Pr to Eu and decrease for Eu to Yb. Exceptionally high values of KCeD, which are similar to those of Ti, result from oxidative scavenging of Ce and support previous suggestions that Ce(IV) is a hydroxide-dominated element in seawater. Yttrium and Gd show lower KD values than their respective neighbours in the REY series. Results of modelling the exchange equilibrium between REY dissolved in seawater and REY sorbed on hydrous Fe-Mn oxides corroborate previous studies that suggested the surface complexation of REY can be approximated by their first hydroxide binding constant. Negative "anomalies" occur for stabilities of bulk surface complexes of Gd, La, and particularly Y. The differences in inorganic surface complex stability between Y and Ho and between Gd and its REE neighbours are similar to those shown by the stabilities of complexes with aminocarboxylic acids and are significantly larger than those shown by stabilities of complexes with carboxylic acids. Hence, sorption of Y and REEs onto hydrous Fe-Mn oxides may contribute significantly to the positive YSN and GdSN anomalies in seawater.

Landscape ecological security response to land use change in the tidal flat reclamation zone, China.

PubMed

Zhang, Runsen; Pu, Lijie; Li, Jianguo; Zhang, Jing; Xu, Yan

2016-01-01

As coastal development becomes a national strategy in Eastern China, land use and landscape patterns have been affected by reclamation projects. In this study, taking Rudong County, China as a typical area, we analyzed land use change and its landscape ecological security responses in the tidal flat reclamation zone. The results show that land use change in the tidal flat reclamation zone is characterized by the replacement of natural tidal flat with agricultural and construction land, which has also led to a big change in landscape patterns. We built a landscape ecological security evaluation system, which consists of landscape interference degree and landscape fragile degree, and then calculated the landscape ecological security change in the tidal flat reclamation zone from 1990 to 2008 to depict the life cycle in tidal flat reclamation. Landscape ecological security exhibited a W-shaped periodicity, including the juvenile stage, growth stage, and maturation stage. Life-cycle analysis demonstrates that 37 years is required for the land use system to transform from a natural ecosystem to an artificial ecosystem in the tidal flat reclamation zone.

Global demand for rare earth resources and strategies for green mining

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dutta, Tanushree

Rare earth elements (REEs) are essential raw materials for emerging renewable energy resources and ‘smart’ electronic devices. Global REE demand is slated to grow at an annual rate of 5% by 2020. This high growth rate will require a steady supply base of REEs in the long run. At present, China is responsible for 85% of global rare earth oxide (REO) production. To overcome this monopolistic supply situation, new strategies and investments are necessary to satisfy domestic supply demands. Concurrently, environmental, economic, and social problems arising from REE mining must be addressed. There is an urgent need to develop efficientmore » REE recycling techniques from end-of-life products, technologies to minimize the amount of REEs required per unit device, and methods to recover them from fly ash or fossil fuel-burning wastes.« less

Global demand for rare earth resources and strategies for green mining.

PubMed

Dutta, Tanushree; Kim, Ki-Hyun; Uchimiya, Minori; Kwon, Eilhann E; Jeon, Byong-Hun; Deep, Akash; Yun, Seong-Taek

2016-10-01

Rare earth elements (REEs) are essential raw materials for emerging renewable energy resources and 'smart' electronic devices. Global REE demand is slated to grow at an annual rate of 5% by 2020. This high growth rate will require a steady supply base of REEs in the long run. At present, China is responsible for 85% of global rare earth oxide (REO) production. To overcome this monopolistic supply situation, new strategies and investments are necessary to satisfy domestic supply demands. Concurrently, environmental, economic, and social problems arising from REE mining must be addressed. There is an urgent need to develop efficient REE recycling techniques from end-of-life products, technologies to minimize the amount of REEs required per unit device, and methods to recover them from fly ash or fossil fuel-burning wastes. Copyright © 2016 Elsevier Inc. All rights reserved.

Investigations of the geochemistry of the rare earth elements in the exogenic cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olivarez, A.M.

1989-01-01

This study investigates the REE geochemistry of three common sediment types (hydrothermal, eolian, and benthic layers) in order to understand their role in the exogenic cycle. The impact of seafloor hydrothermal activity upon the REE content of seawater was investigated by comparing REE/Fe ratios of hydrothermal sediments with end-member plume values. Hydrothermal activity results in a net depletion in REE's from seawater, primarily due to the large scavenging capacity of iron oxyhydroxides which precipitate from these solutions. The discrepancy between the predicted (positive) versus observed (negative) Eu anomaly of seawater was investigated by calculating REE scavenging indices for DSDP Sitemore » 598 hydrothermal precipitates is proportional to REE concentration in the fluid phase. The REE content of Lake Superior benthic layers are dominated by lithogenous sources, with minor contributions from the water column. The mechanism of REE removal from the water column may involve scavenging by Fe-rich phases. The eolian dust component of Pacific sediments is derived from two sources: the continental crust and oceanic crust, probably ash from circum-Pacific volcanism. The relative amount of the two end-members influences the median grain size. An eolian flux maximum exists between 35{degree}N and 42{degree}N in the northwest Pacific. This region also receives more eolian materials during glacial versus interglacial stages. A comparison of chemically treated versus untreated loess samples suggests that eolian dust is not a significant source of dissolved REE's to the oceans.« less

Evaluation of rare earth elements in groundwater of Lagos and Ogun States, Southwest Nigeria.

PubMed

Ayedun, H; Arowolo, T A; Gbadebo, A M; Idowu, O A

2017-06-01

Rare earth elements in our environment are becoming important because of their utilization in permanent magnets, lamp phosphors, superconductors, rechargeable batteries, catalyst, ceramics and other applications. This study was conducted to evaluate the level of rare earth elements (REE) and the variability of their anomalous behavior in groundwater samples collected from Lagos and Ogun States, Southwest, Nigeria. REE concentrations were determined in 170 groundwater samples using inductively coupled plasma-mass spectrometry, while the physicochemical parameters were determined using standard methods. Lagos State groundwater is enriched with REE [sum REEs range (mean ± SD)]; [0.365-488 (69.5 ± 117)] µg L -1 than Ogun State groundwater [sum REEs range (mean ± SD)]; [1.14-232 (22.6 ± 41.1)] µg L -1 . Boreholes are more enriched with REEs than wells. Significant (P < 0.05) positive correlation (R = Pearson) was recorded in Lagos State groundwater between sum REEs and Fe (R = 0.55). However, there were no significant correlations between sum REEs, pH (R = 0.073) and HCO 3 2- (R = 0.157) in Ogun State groundwater. Chondrite-normalized plot shows that Lagos groundwater exhibits positive Ce anomaly, while Ogun State groundwater does not. The source of REE in Lagos State may be from the ocean and leaching from wastes dumpsites, while the source in Ogun State groundwater may be from the rocks.

Bach music in preterm infants: no 'Mozart effect' on resting energy expenditure.

PubMed

Keidar, H Rosenfeld; Mandel, D; Mimouni, F B; Lubetzky, R

2014-02-01

To study whether Johan Sebastian Bach music has a lowering effect on resting energy expenditure (REE) similar to that of Wolfgang Amadeus Mozart music. Prospective, randomized clinical trial with cross-over in 12 healthy, appropriate weights for gestational age (GA), gavage fed, metabolically stable, preterm infants. Infants were randomized to a 30-min period of either Mozart or Bach music or no music over 3 consecutive days. REE was measured every minute by indirect calorimetry. Three REE measurements were performed in each of 12 infants at age 20±15.8 days. Mean GA was 30.17±2.44 weeks and mean birthweight was 1246±239 g. REE was similar during the first 10-min of all three randomization periods. During the next 10-min period, infants exposed to music by Mozart had a trend toward lower REE than when not exposed to music. This trend became significant during the third 10-min period. In contrast, music by Bach or no music did not affect significantly REE during the whole study. On average, the effect size of Mozart music upon REE was a reduction of 7.7% from baseline. Mozart music significantly lowers REE in preterm infants, whereas Bach music has no similar effect. We speculate that 'Mozart effect' must be taken into account when incorporating music in the therapy of preterm infants, as not all types of music may have similar effects upon REE and growth.

Resting Energy Expenditure Prediction in Recreational Athletes of 18–35 Years: Confirmation of Cunningham Equation and an Improved Weight-Based Alternative

PubMed Central

ten Haaf, Twan; Weijs, Peter J. M.

2014-01-01

Introduction Resting energy expenditure (REE) is expected to be higher in athletes because of their relatively high fat free mass (FFM). Therefore, REE predictive equation for recreational athletes may be required. The aim of this study was to validate existing REE predictive equations and to develop a new recreational athlete specific equation. Methods 90 (53M, 37F) adult athletes, exercising on average 9.1±5.0 hours a week and 5.0±1.8 times a week, were included. REE was measured using indirect calorimetry (Vmax Encore n29), FFM and FM were measured using air displacement plethysmography. Multiple linear regression analysis was used to develop a new FFM-based and weight-based REE predictive equation. The percentage accurate predictions (within 10% of measured REE), percentage bias, root mean square error and limits of agreement were calculated. Results The Cunningham equation and the new weight-based equation and the new FFM-based equation performed equally well. De Lorenzo's equation predicted REE less accurate, but better than the other generally used REE predictive equations. Harris-Benedict, WHO, Schofield, Mifflin and Owen all showed less than 50% accuracy. Conclusion For a population of (Dutch) recreational athletes, the REE can accurately be predicted with the existing Cunningham equation. Since body composition measurement is not always possible, and other generally used equations fail, the new weight-based equation is advised for use in sports nutrition. PMID:25275434

Association of Sub-continental and Asthenosphere related Volcanism in NW Iran,Implication forMantle thermal perturbation induced by slab break off and collision event

NASA Astrophysics Data System (ADS)

Jahangiri, A.

2017-12-01

Cenozoic magmatic rocks occur extensively in the north of the Zagros suture zone and constitute a significant component of the continental crust in this segment of the Alpine-Himalayan orogenic belt. They range in age from Eocene to quaternary. Miocene to Plio-Quaternary volcanism with post-collisional related significant is covered vast areas in NW Iran. These volcanic rocks can be divided into three different sub-groups on the basis of their mineralogy, geochemistry and magma sources including: 1. alkaline leucite-bearing mafic rocks, which are characterized with high ratios of K2O/Na2O, high content LILE and low HFS elements like Ti, Nb and Ta. They are display fractionated REE patterns and based on different discrimination diagrams show similarity with subduction related magmas. 2- Olivine basalt to trachy-basaltic samples which shows similarity to within plate basalts with high content of TiO2, Nb, Ta and fractionated REE pattern. However, compared with a global average of OIB, they are display slightly higher LIL elements and lower HFS elements concentrations, features that resemble to the arc magmas and suggest that the source of the magmas may have been contaminated by slab-derived fluids. These rocks have simple mineralogical composition with plagioclase, clinopyroxene and olivine. 3- Dominant dacitic volcanic rocks with adakitic geochemical characteristics such as highly fractionate REE pattern and high Sr/Y ratio. Generation of adakitic magmas can be related to increased temperatures in the subduction zone due to mantle upwelling and slab tearing. Subsequent asthenospheric upwelling could be caused direct melting of sub-continental mantle to produce the alkaline magmas, with high contents of K2O, MgO and volatile rich phase's potassic magmas that led to crystallization of leucite, phlogopite, apatite and olivine in studied samples. Rupture of the continental lithosphere by strike-slip-related transtensional deformation might have caused decompression partial melting of the asthenospheric mantle and generating alkali basalts. Continental lithosphere rupturing is occurred subsequent to slab breakoff/delamination and sub-continental mantle thermal perturbation processes following closure of Neo-Tethys and collision of Arabian plate with microplate of Iran.

The principal rare earth elements deposits of the United States-A summary of domestic deposits and a global perspective

USGS Publications Warehouse

Long, Keith R.; Van Gosen, Bradley S.; Foley, Nora K.; Cordier, Daniel

2010-01-01

The rare earth elements (REE) are fifteen elements with atomic numbers 57 through 71, from lanthanum to lutetium ('lanthanides'), plus yttrium (39), which is chemically similar to the lanthanide elements and thus typically included with the rare earth elements. Although industrial demand for these elements is relatively small in tonnage terms, they are essential for a diverse and expanding array of high-technology applications. REE-containing magnets, metal alloys for batteries and light-weight structures, and phosphors are essential for many current and emerging alternative energy technologies, such as electric vehicles, energy-efficient lighting, and wind power. REE are also critical for a number of key defense systems and other advanced materials. Section 843 of the National Defense Authorization Act for Fiscal Year 2010, Public Law 111-84, directs the Comptroller General to complete a report on REE materials in the defense supply chain. The Office of Industrial Policy, in collaboration with other U.S. Government agencies, has initiated (in addition to this report) a detailed study of REE. This latter study will assess the Department of Defense's use of REE, as well as the status and security of domestic and global supply chains. That study will also address vulnerabilities in the supply chain and recommend ways to mitigate any potential risks of supply disruption. To help conduct this study, the Office of Industrial Policy asked the U.S. Geological Survey (USGS) to report on domestic REE reserves and resources in a global context. To this end, the enclosed report is the initial USGS contribution to assessing and summarizing the domestic REE resources in a global perspective. In 2009, the Mineral Resources Program of the USGS organized a new project under the title Minerals at Risk and For Emerging Technologies in order to evaluate mineral resource and supply issues of rare metals that are of increasing importance to the national economy. Leaders and members of this project, with the assistance of the USGS National Minerals Information Center, prepared the enclosed USGS report on domestic REE resources. The USGS Mineral Resources Program has investigated domestic and selected foreign REE resources for many decades, and this report summarizes what has been learned from this research. The USGS National Minerals Information Center (formerly Minerals Information Team) has monitored global production, trade, and resources for an equally long period and is the principal source of statistics used in this report. The objective of this study is to provide a nontechnical overview of domestic reserves and resources of REE and possibilities for utilizing those resources. At the present time, the United States obtains its REE raw materials from foreign sources, almost exclusively from China. Import dependence upon a single country raises serious issues of supply security. In a global context, domestic REE resources are modest and of uncertain value; hence, available resources in traditional trading partners (such as Canada and Australia) are of great interest for diversifying sources of supply. This report restates basic geologic facts about REE relevant to assessing security of supply, followed by a review of current United States consumption and imports of REE, current knowledge of domestic resources, and possibilities for future domestic production. Further detail follows in a deposit-by-deposit review of the most significant domestic REE deposits (see index map). Necessary steps to develop domestic resources are discussed in a separate section, leading into a review of current domestic exploration and a discussion of the value of a future national mineral resource assessment of REE. The report also includes an overview of known global REE resources and discusses the reliability of alternative foreign sources of REE.

Characterization of Rare Earth Element Minerals in Coal Utilization Byproducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montross, Scott N.; Verba, Circe A.; Collins, Keith

The United States currently produces over 100 million tons of coal utilization byproducts (CUB) per year in the form of fly ash, bottom ash, slag, and flue gas (American Coal Ash Association (ACCA), 2015). But this “waste material” also contains potentially useful levels of rare earth elements (REE). Rare earth elements are crucial for many existing and emerging technologies, but the U.S. lacks a domestic, sustainable REE source. Our project explored the possibility of developing a supply of REEs for U.S. technologies by extracting REEs from CUBs. This work offers the potential to reduce our dependence on other countries formore » supply of these critical elements (NETL, REE 2016 Project Portfolio). Geologic and diagenetic history, industrial preparation methods, and the specific combustion process all play major roles in the composition of CUB. During combustion, inorganic mineral phases of coal particles are fluidized at temperatures higher than 1400oC, so inorganic mineral materials are oxidized, fused, disintegrated, or agglomerated into larger spherical and amorphous (non-crystalline) particles. The original mineralogy of the coal-containing rock and heating/cooling of the material significantly affects the composition and morphology of the particles in the combustion byproduct (Kutchko and Kim, 2006). Thus, different types of coal/refuse/ash must be characterized to better understand mineral evolution during the combustion process. Our research focused on developing a working model to address how REE minerals behave during the combustion process: this research should help determine the most effective engineering methods for extracting REEs from CUBs. We used multimodal imaging and image processing techniques to characterize six rock and ash samples from different coal power plants with respect to morphology, grain size, presence of mineral phases, and elemental composition. The results of these characterization activities provided thresholds for realizing the occurrence of REE mineral phases in CUB and allowed us to calculate structural and volumetric estimates of REE. Collectively, the rock and coal ash samples contained minerals such as quartz, kaolinite, muscovite/illite, iron oxide (as hematite or magnetite), mullite, and clinochlore. Trace minerals included pyrite, zircon, siderite, rutile, diopside, foresterite, gypsum, and barite. We identified REE phosphate minerals monazite (Ce,La,Nd,Th)(PO 4,SiO 4), xenotime (YPO 4,SiO 4), and apatite (Ca 5(PO 4) 3(F,Cl,OH) via SEM and electron microprobe analysis: these materials generally occurred as 1-10 μm-long crystals in the rock and ash samples. As has been shown in other studies, amorphous material-aluminosilicate glass or iron oxyhydroxide-are the major components of coal fly and bottom ash. Trace amounts of amorphous calcium oxide and mixed element (e.g., Al-Si-Ca-Fe) slag are also present. Quartz, mullite, hematite, and magnetite are the crystalline phases present. We found that REEs are present as monomineralic grains dispersed within the ash, as well as fused to or encapsulated by amorphous aluminosilicate glass particles. Monazite and xenotime have relatively high melting points (>1800 °C) compared to typical combustion temperatures; our observations indicate that the REE-phosphates, which presumably contribute a large percentage of REE to the bulk ash REE pool, as measured by mass spectroscopy, are largely unaltered by the combustion. Our study shows that conventional coal combustion processes sequester REE minerals into aluminosilicate glass phases, which presents a new engineering challenge for extracting REE from coal ash. The characterization work summarized in this report provides a semi-quantitative assessments of REE in coal-containing rock and CUB. The data we obtained from 2- and 3-D imaging, elemental mapping, volumetric estimates, and advanced high-resolution pixel classification successfully identified the different mineral phases present in CUB. Further, our characterization results can guide techniques for extracting REEs from CUB, or other geologic and engineered materials. Whilst, interpretations will inform future REE separation and extraction techniques and technologies practical for commercial utilization of combustion byproducts generated by power plants.« less

Novel Polyethylenimine–Acrylamide/SiO 2 Hybrid Hydrogel Sorbent for Rare-Earth-Element Recycling from Aqueous Sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Qiuming; Wilfong, Walter C.; Kail, Brian W.

Recycling rare earth elements (REEs) becomes increasingly important due to their supply vulnerability and increasing demands in industry, agriculture, and national security. Hybrid hydrogel sorbents were outstanding due to their high stability and selectivity. Organic-inorganic hybrid hydrogels were synthesized by thermo-polymerization of acrylamide onto PEI polymer chain with N,N’-methylene bisacrylamide as a crosslinker. The grafted network was evidenced by DRIFTS and XPS. The porous structure was observed by SEM. Crosslink degree, PEI grafting degree, and SiO 2 concentration were studied to optimize the REEs adsorption. The pH value of the medium greatly affected REE adsorption capacity, where the nearly neutralmore » conditions gave the strongest bonding of REEs to active sites. Moreover, kinetic studies showed that the rate-determining step of the adsorption process was chemical sorption, and that REE diffusion within micropores was the control step for, specifically, intraparticle diffusion. The adsorbents showed excellent selectivity and recyclability for REEs through 5 adsorption-desorption cycles in contact with synthetic acid mine drainage solution. A high separation toward REEs over fouling metals was achieved by using a citrate-based buffer eluent solution. This hybrid hydrogel shows promise for the recycling of REEs from aqueous solutions.« less

Novel Polyethylenimine–Acrylamide/SiO 2 Hybrid Hydrogel Sorbent for Rare-Earth-Element Recycling from Aqueous Sources

DOE PAGES

Wang, Qiuming; Wilfong, Walter C.; Kail, Brian W.; ...

2017-09-14

Recycling rare earth elements (REEs) becomes increasingly important due to their supply vulnerability and increasing demands in industry, agriculture, and national security. Hybrid hydrogel sorbents were outstanding due to their high stability and selectivity. Organic-inorganic hybrid hydrogels were synthesized by thermo-polymerization of acrylamide onto PEI polymer chain with N,N’-methylene bisacrylamide as a crosslinker. The grafted network was evidenced by DRIFTS and XPS. The porous structure was observed by SEM. Crosslink degree, PEI grafting degree, and SiO 2 concentration were studied to optimize the REEs adsorption. The pH value of the medium greatly affected REE adsorption capacity, where the nearly neutralmore » conditions gave the strongest bonding of REEs to active sites. Moreover, kinetic studies showed that the rate-determining step of the adsorption process was chemical sorption, and that REE diffusion within micropores was the control step for, specifically, intraparticle diffusion. The adsorbents showed excellent selectivity and recyclability for REEs through 5 adsorption-desorption cycles in contact with synthetic acid mine drainage solution. A high separation toward REEs over fouling metals was achieved by using a citrate-based buffer eluent solution. This hybrid hydrogel shows promise for the recycling of REEs from aqueous solutions.« less

Planktonic foraminiferal rare earth elements as a potential new aeolian dust proxy

NASA Astrophysics Data System (ADS)

Chou, C.; Liu, Y.; Lo, L.; Wei, K.; Shen, C.

2012-12-01

Characteristics of rare earth elements (REEs) have widely been used as important tracers in many fields of earth sciences, including lithosphere research, environmental change, ocean circulation and other natural carbonate materials. Foraminiferal test REE signatures have been suggested to reflect ambient seawater conditions and serve as valuable proxies in the fields of paleoceanography and paleoclimate. Here we present a 60-kyr planktonic foraminifera Globigerinoides ruber (white, 250-300 μm) REE record of a sediment core MD05-2925 (9°20.61'S, 151°27.61'E, water depth 1660 m) from the Solomon Sea. The REE diagram shows two dominant sources of local seawater and nearby terrestrial input. The variability of foraminiferal REE/Ca time series is different from Mg/Ca-inferred sea surface temperature and δ18O records during the past 60-kyr. This inconsistency suggests that planktonic foraminiferal REE content cannot result only from changes in ice volume and temperature. Synchroneity between high planktonic foraminiferal REE content and Antarctic ice core dust amount record implies the same dust sources, probably from Australia or mainland China. Our results suggest that foraminiferal REE can potentially be as a new dust proxy and record dry/humid conditions at the source area.

Do patients with amyotrophic lateral sclerosis (ALS) have increased energy needs?

PubMed

Vaisman, Nachum; Lusaus, Michal; Nefussy, Beatrice; Niv, Eva; Comaneshter, Doron; Hallack, Ron; Drory, Vivian E

2009-04-15

Nutritional status is a prognostic factor for survival in amyotrophic lateral sclerosis (ALS) patients. We investigated the contribution of some of the components contributing to resting energy expenditure (REE) in order to determine whether potentially higher energy needs should be considered for these patients. Thirty three ALS patients and 33 age- and gender-matched healthy controls participated. REE was measured by an open-circuit indirect calorimeter, body composition by dual energy X-ray absorptiometry, and estimated caloric intake by 7-day food records. Patients had lower body mass indices and lower lean body mass (LBM) than healthy controls. REE values (as a percentage of predicted) was similar but increased when normalized by LBM (P<0.001). LBM and REE decreased while REE/LBM increased in ten patients who were reassessed 6 months later. A model for predicting measured REE was constructed based on the different components, with 86% prediction of its variability. ALS is associated with increased REE. Various factors, such as poor caloric intake and mechanical ventilation, may mask this tendency. All the above parameters need to be considered during nutritional intervention to prevent additional muscle loss.

Provenance, tectonic setting and source-area weathering of the lower Cambrian sediments of the Parahio valley in the Spiti basin, India

NASA Astrophysics Data System (ADS)

Pandey, Shivani; Parcha, Suraj K.

2017-03-01

The geochemical study of siliciclastic rocks from the Lower Cambrian of Parahio Valley has been studied to describe the provenance, chemical weathering and tectonic setting. The K2O/Al2O3 ratio and positive correlation of Co ( r=0.85), Ni ( r=0.86), Zn ( r=0.82), Rb ( r=0.98) with K2O reflects that the presence of clay minerals control the abundances of these elements and suggests a warm and humid climate for this region. The chondrite normalized REE pattern of the samples is equivalent to upper continental crust, which reflects enriched LREE and flat HREE with negative Eu anomaly. The tectonic setting discriminant diagram log[K2O/Na2O] vs. SiO2; [SiO2/Al2O3] vs. log[K2O/Na2O]; [SiO2/20] - [K2O+Na2O] - [TiO2+Fe2O3+MgO] indicates transitional tectonic setting from an active continental margin to a passive margin. The discriminant function plot indicates quartzose sedimentary provenance, and to some extent, the felsic igneous provenance, derived from weathered granite, gneissic terrain and/or from pre-existing sedimentary terrain. The CIA value indicates low to moderate degree of chemical weathering and the average ICV values suggests immature sediments deposited in tectonically active settings. The A-CN-K diagram indicates that these sediments were generated from source rocks of the upper continental crust.

Repetitive Regeneration of Media #1 in a Dynamic Column Extraction using Brine #1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gary Garland

This data is from a regeneration study from a dynamic column extraction experiment where we ran a solution of REE's through a column of media #1 then stripped the REE's off the media using 2M HNO3 solution. We then re-equilibrated the media and repeated the process of running a REE solution through the column and stripping the REE's off the media and comparing the two runs.

Magnesian anorthosites and associated troctolites and dunite in Apollo 14 breccias

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindstrom, M.M.; Knapp, S.A.

1984-11-15

Magnesian anorthosite, a new type of pristine lunar highlands rock, has been found in Apollo 14 breccias. It has primitive (high Ca and Mg) silicate mineral compositions, and high and variable REE concentrations. Variations in REE contents can be accounted for by variations in modal abundance of REE-rich apatite. Magnesian anorthosites are associated with troctolites and a dunite with very similar mineral compositions and it is suggested that all crystallized from a differentiated troctolitic intrusion. The origin of the REE-rich apatite is enigmatic. It is unlikely to have crystallized from an igneous liquid in equilibrium with the major minerals inmore » the anorthosite. Possible origins are assimilation of urKREEP or metasomatism by REE-rich fluids. REE-rich alkali anorthosites and gabbronorites are also found and are likely to be related to KREEP basalt magmas. Lunar compositional associations are distributed in a regional rather than global manner.« less

Bio- and mineral acid leaching of rare earth elements from synthetic phosphogypsum

NASA Astrophysics Data System (ADS)

Hu, Z.; Antonick, P.; Fujita, Y.; Reed, D. W.; Riman, R.; Eslamimanesh, A.; Das, G.; Anderko, A.; Wu, L.; Shivaramaiah, R.; Navrotsky, A.

2017-12-01

Rare earth elements (REE) are critical to many clean energy technologies. However, the lack of U.S. domestic production and the reliance on imported REE put U.S. energy security at risk. Consequently development of new sources is of strategic interest. Global phosphate deposits contain 27 million tons of REE and 38% of these REE end up in phosphogypsum (PG) waste during phosphate fertilizer production. Recovering REE from PG is a first step toward a trash-to-treasure transformation. We studied the leaching of REE from synthetic PG samples containing Y, Nd, or Eu using a suite of lixiviants including spent medium from the growth of the bacterium Gluconobacter oxydans ("biolixiviant"), gluconic acid, common mineral acids (phosphoric and sulfuric), and water. Synthetic PG was used to facilitate the comparison of the different lixiviants; real PG waste is extremely heterogeneous. Gluconic acid was the predominant identified organic acid in the biolixiviant. The leaching efficiency of the acidic lixiviants at the same pH (2.1) or molar concentration as gluconic acid in the biolixiviant (220 mM) were compared and rationalized by thermodynamic simulation using the mixed-solvent electrolyte model. Initial results indicate that the biolixiviant was more effective at leaching the REE than the mineral acids at pH 2.1. At 220 mM acid concentrations, sulfuric acid was the most effective, followed by the biolixiviant. Interestingly, for a given lixiviant, the leaching behavior of the REE differed. This study provides insight into the definition of an efficient lixiviant for leaching REE from phosphate fertilizer production waste.

Relative contribution of organs other than brain to resting energy expenditure is consistent among male power athletes.

PubMed

Oshima, Satomi; Miyauchi, Sakiho; Asaka, Meiko; Kawano, Hiroshi; Taguchi, Motoko; Torii, Suguru; Higuchi, Mitsuru

2013-01-01

We have previously shown that resting energy expenditure (REE) adjusted by fat-free mass (FFM) in male college athletes remains consistent regardless of FFM. The FFM comprises internal organs with high metabolic activity, such as liver and brain, which account for 60 to 80% of REE in adults. The purpose of the present study is to examine the contribution of internal organs to the REE of the FFM fraction among male power athletes. The study included 37 American male college football players. REE was measured by indirect calorimetry and body composition was measured by dual energy X-ray absorptiometry (DXA). Mass of brain, liver, and kidneys was measured by MRI and mass of heart was estimated by echocardiography. Normal levels of thyroid hormone (triiodothyronine: T3) were confirmed in all subjects prior to the analysis. Multiple regression analysis was used to assess the influence of FFM, fat mass (FM), T3, and mass of organs on variance of REE. Average body weight and FFM were 81.2±11.3 kg and 67.7±7.4 kg, respectively. The relative contributions of liver, kidneys, and heart to REE were consistent regardless of FFM, while the REE of brain was negatively correlated with FFM (r=-0.672, p<0.001). Only FFM and T3 were found to be independent factors influencing REE. These results suggest that a steady contribution of internal organs other than the brain is the major reason for the consistency of the REE/FFM ratio in male power athletes.

Revisit of rare earth element fractionation during chemical weathering and river sediment transport

NASA Astrophysics Data System (ADS)

Su, Ni; Yang, Shouye; Guo, Yulong; Yue, Wei; Wang, Xiaodan; Yin, Ping; Huang, Xiangtong

2017-03-01

Although rare earth element (REE) has been widely applied for provenance study and paleoenvironmental reconstruction, its mobility and fractionation during earth surface processes from weathering to sediment deposition remain more clarification. We investigated the REE fractionations during chemical weathering and river sediment transport based on the systematic observations from a granodiorite-weathering profile and Mulanxi River sediments in southeast China. Two chemical phases (leachates and residues) were separated by 1 N HCl leaching and the leachates account for 20-70% of the bulk REE concentration. REEs in the weathering profile have been mobilized and fractionated to different extents during chemical weathering and pedogenesis. Remarkable cerium anomalies (Ce/Ce* = 0.1-10.6) occur during weathering as a result of coprecipitation with Mn (hydro)oxides in the profile, while poor or no Ce anomalies in the river sediments were observed. This contrasting feature sheds new light on the indication of Ce anomaly for redox change. The hydraulic sorting-induced mineral redistribution can further homogenize the weathering and pedogenic alterations and thus weaken the REE fractionations in river sediments. The mineral assemblage is the ultimate control on REE composition, and the Mn-Fe (hydro)oxides and secondary phosphate minerals are the main hosts of acid-leachable REEs while the clay minerals could be important reservoirs for residual REEs. We thus suggest that the widely used REE proxies such as (LREE/HREE)UCC ratio in the residues is reliable for the indication of sediment provenance, while the ratio in the leachates can indicate the total weathering process to some extent.

Handheld calorimeter is a valid instrument to quantify resting energy expenditure in hospitalized cirrhotic patients: a prospective study.

PubMed

Glass, Cathy; Hipskind, Peggy; Cole, Denise; Lopez, Rocio; Dasarathy, Srinivasan

2012-10-01

Nutrition management of cirrhosis in hospitalized patients is overlooked despite the clinical significance of sarcopenia or loss of muscle mass in cirrhosis. Determining optimal nutrition requirement needs precise measurement of resting energy expenditure (REE) in the cirrhotic patient. Predictive equations are not accurate, and the metabolic cart is expensive and cumbersome. The authors therefore performed a prospective study to examine the feasibility and accuracy of a handheld respiratory calorimeter (HHRC) in quantifying the REE in hospitalized cirrhotic patients not in the intensive care unit. The study was done in 2 phases: in the first phase, the REE of 24 consecutive healthy volunteers was measured using an HHRC in different positions. The objective of this phase was to identify the impact of body and arm position on measured REE. Subsequently, in the second phase of the study, REE was measured using the HHRC and the metabolic cart in 25 consecutive well-characterized, hospitalized cirrhotic patients. The degree of concordance was calculated. Body position and arm position did not significantly affect the measured REE using HHRC. In patients with cirrhosis, the mean measured REE (kcal/d) using the HHRC was 1453.2 ± 319.3 in the hospital room, 1525.6 ± 305.2 in a quiet environment, and 1553.7 ± 270.6 with the metabolic cart (P > .1). Predicted REE using 2 widely used equations did not correlate either with each other or with the measured REE. HHRC is a valid, feasible, and rapid method to determine optimal caloric needs in hospitalized cirrhotic patients.

Advanced Characterization of Rare Earth Elements in Coal Utilization Byproducts

NASA Astrophysics Data System (ADS)

Verba, C.; Scott, M.; Dieterich, M.; Poston, J.; Collins, K.

2016-12-01

Rare earth elements (REE) in various forms (e.g., crystalline mineral phases; adsorbed/absorbed state on and into organic macerals, neoformed glass from flyash or bottom ash) from domestic feedstocks such as coal deposits to coal utilization byproducts (CUB) have the potential to reduce foreign REE dependence and increase domestic resource security. Characterization is critical for understanding environmental risks related to their fate and transport as well as determining the most practical and economical techniques for concentrating the REE and converting them into chemical stocks for manufacturing. Several complementary electron microscopy (SEM-EDS, EPMA-WDS, FIB-SEM, cathodoluminescence, and XRD) and post image processing techniques were used to understand REE transition from coal to CUB. Sites of interest were identified and imaged and respective elemental x-ray maps acquired and montaged. Pixel classification of SEM imagers was completed using image analysis techniques to quantify the distribution of REE associated features. Quantitative elemental analysis of phases were completed using EMPA-WDS followed by FIB-SEM. The FIB-SEM results were reconstructed into 3D volumes and features of interest (e.g. monazite) were analyzed to determine the structure and volumetric estimation of REEs and thus predict detrital REE phases to ICP-MS results. Trace minerals were identified as pyrite, zircon, REE-phosphates' (monazite, xenotime), and barite within the coal tailings. In CUB, amorphous aluminosilicates, iron oxide cenospheres, and calcium oxides were present; monazite appear to be unaltered and unaffected by the combustion process in these samples. Thermal decomposition may have occurred due to presence of detrital zircon and xenotime and subsequent thin Ca-oxide coating enriched in trace REEs.

Geochemistry, Nd-Pb Isotopes, and Pb-Pb Ages of the Mesoproterozoic Pea Ridge Iron Oxide-Apatite–Rare Earth Element Deposit, Southeast Missouri

USGS Publications Warehouse

Ayuso, Robert A.; Slack, John F.; Day, Warren C.; McCafferty, Anne E.

2016-01-01

Iron oxide-apatite and iron oxide-copper-gold deposits occur within ~1.48 to 1.47 Ga volcanic rocks of the St. Francois Mountains terrane near a regional boundary separating crustal blocks having contrasting depleted-mantle Sm-Nd model ages (TDM). Major and trace element analyses and Nd and Pb isotope data were obtained to characterize the Pea Ridge deposit, improve identification of exploration targets, and better understand the regional distribution of mineralization with respect to crustal blocks. The Pea Ridge deposit is spatially associated with felsic volcanic rocks and plutons. Mafic to intermediate-composition rocks are volumetrically minor. Data for major element variations are commonly scattered and strongly suggest element mobility. Ratios of relatively immobile elements indicate that the felsic rocks are evolved subalkaline dacite and rhyolite; the mafic rocks are basalt to basaltic andesite. Granites and rhyolites display geochemical features typical of rocks produced by subduction. Rare earth element (REE) variations for the rhyolites are diagnostic of rocks affected by hydrothermal alteration and associated REE mineralization. The magnetite-rich rocks and REE-rich breccias show similar REE and mantle-normalized trace element patterns.Nd isotope compositions (age corrected) show that: (1) host rhyolites have ɛNd from 3.44 to 4.25 and TDM from 1.51 to 1.59 Ga; (2) magnetite ore and specular hematite rocks display ɛNd from 3.04 to 4.21 and TDM from 1.6 to 1.51 Ga, and ɛNd from 2.23 to 2.81, respectively; (3) REE-rich breccias have ɛNd from 3.04 to 4.11 and TDM from 1.6 to 1.51 Ga; and (4) mafic to intermediate-composition rocks range in ɛNd from 2.35 to 3.66 and in TDM from 1.66 to 1.56. The ɛNd values of the magnetite and specular hematite samples show that the REE mineralization is magmatic; no evidence exists for major overprinting by younger, crustal meteoric fluids, or by externally derived Nd. Host rocks, breccias, and magnetite ore shared a common origin from a similar source.Lead isotope ratios are diverse: (1) host rhyolite has 206Pb/204Pb from 24.261 to 50.091; (2) Pea Ridge and regional galenas have 206Pb/204Pb from 16.030 to 33.548; (3) REE-rich breccia, magnetite ore, and specular hematite rock are more radiogenic than galena; (4) REE-rich breccias have high 206Pb/204Pb (38.122–1277.61) compared to host rhyolites; and (5) REE-rich breccias are more radiogenic than magnetite ore and specular-hematite rock, having 206Pb/204Pb up to 230.65. Radiogenic 207Pb/206Pb age estimates suggest the following: (1) rhyolitic host rocks have ages of ~1.50 Ga, (2) magnetite ore is ~1.44 Ga, and (3) REE-rich breccias are ~1.48 Ga. These estimates are broadly consistent and genetically link the host rhyolite, REE-rich breccia, and magnetite ore as being contemporaneous.Alteration style and mineralogical or textural distinctions among the magnetite-rich rocks and REE-rich breccias do not correlate with different isotopic sources. In our model, magmatic fluids leached metals from the coeval felsic rocks (rhyolites), which provided the metal source reflected in the compositions of the REE-rich breccias and mineralized rocks. This model allows for the likelihood of contributions from other genetically related felsic and intermediate to more mafic rocks stored deeper in the crust. The deposit thus records an origin as a magmatic-hydrothermal system that was not affected by Nd and Pb remobilization processes, particularly if these processes also triggered mixing with externally sourced metal-bearing fluids. The Pea Ridge deposit was part of a single, widespread, homogeneous mixing system that produced a uniform isotopic composition, thus representing an excellent example of an igneous-dominated system that generated coeval magmatism and REE mineralization. Geochemical features suggest that components in the Pea Ridge deposit originated from sources in an orogenic margin. Basaltic magmatism produced by mantle decompression melting provided heat for extracting melts from the middle or lower crust. Continual addition of mafic magmas to the base of the subcontinental lithosphere, in a back-arc setting, remelted calc-alkaline rocks enriched in metals that were stored in the crust.The St. Francois Mountains terrane is adjacent to the regional TDM line (defined at a value of 1.55 Ga) that separates ~1600 Ma basement to the west, from younger basements to the east. Data for Pea Ridge straddle the TDM values proposed for the line. The Sm-Nd isotope system has been closed since formation of the deposit and the original igneous signatures have not been affected by cycles of alteration or superimposed mineralizing events. No evidence exists for externally derived Nd or Sm. The source region for metals within the Pea Ridge deposit had a moderate compositional variation and the REE-rich breccias and mineralized rocks are generally isotopically homogeneous. The Pea Ridge deposit thus constitutes a distinctive isotopic target for use as a model in identifying other mineralized systems that may share the same metal source in the St. Francois Mountains terrane and elsewhere in the eastern Granite-Rhyolite province.

Assessing anthropogenic levels, speciation, and potential mobility of rare earth elements (REEs) in ex-tin mining area.

PubMed

Khan, Aysha Masood; Yusoff, Ismail; Bakar, Nor Kartini Abu; Bakar, Ahmad Farid Abu; Alias, Yatimah

2016-12-01

A study was carried out to determine the level of rare earth elements (REEs) in water and sediment samples from ex-mining lakes and River in Kinta Valley, Perak, Malaysia. Surface water and sediments from an ex-mining lake and Kinta River water samples were analyzed for REEs by inductively coupled plasma mass spectrometry. The total concentration of REEs in the ex-mining lake water samples and sediments were found to be 3685 mg/l and 14159 mg/kg, respectively, while the total concentration of REEs in Kinta River water sample was found to be 1224 mg/l. REEs in mining lake water were found to be within 2.42 mg/l (Tb) to 46.50 mg/l (Ce), while for the Kinta River, it was 1.33 mg/l (Ho) to 29.95 mg/l (Ce). Sediment samples were also found with REEs from 9.81 mg/kg (Ho) to 765.84 mg/kg (Ce). Ce showed the highest average concentrations for mining lake (3.88 to 49.08 mg/l) and Kinta River (4.44 to 33.15 mg/l) water samples, while the concentration of La was the highest (11.59 to 771.61 mg/kg) in the mining lake sediment. Lu was shown to have the highest enrichment of REEs in ex-mining lake sediments (107.3). Multivariate statistical analyses such as factor analysis and principal component analysis indicated that REEs were associated and controlled by mixed origin, with similar contributions from anthropogenic and geogenic sources. The speciation study of REEs in ex-tin mining sediments using a modified five-stage sequential extraction procedure indicated that yttrium (Y), gadolinium (Gd), and lanthanum (La) were obtained at higher percentages from the adsorbed/exchanged/carbonate fraction. The average potential mobility of the REEs was arranged in a descending order: Yb > Gd > Y = Dy > Pr > Er > Tm > Eu > Nd > Tb > Sc > Lu > Ce > La, implying that under favorable conditions, these REEs could be released and subsequently pollute the environment.

Resting Energy Expenditure in Patients with Stroke during the Subacute Phases - Relationships with Stroke Types, Location, Severity of Paresis, and Activities of Daily Living.

PubMed

Kawakami, Michiyuki; Liu, Meigen; Wada, Ayako; Otsuka, Tomoyoshi; Nishimura, Atsuko

2015-01-01

The energy demands in patients with stroke during the subacute phases are unclear. However, this information is essential for appropriate clinical and nutritional management. The aims of this study were to determine the resting energy expenditure (REE) during the subacute phases, examine its relationships with stroke types, location, severity of hemiparesis, and activities of daily living (ADL), and evaluate whether estimation of REE from the Harris-Benedict equation (HB) requires the addition of a 'stress factor' to capture possible additional REE imposed by stroke. We measured REE in 95 patients with subacute stroke (53.5 ± 16.6 days post-stroke) with indirect calorimetry, and compared it with predicted values of energy expenditure estimated from the HB (expressed as percentage). Patients were admitted for rehabilitation of their first ischemic or nonsurgical hemorrhagic stroke. The severity of hemiparesis was assessed with the motor items of the Stroke Impairment Assessment Set (SIAS). The ADL was assessed with the Functional Independence Measure (FIM). We compared REE and %HB of the two groups divided by hemiparesis severity and ADL limitation using the Student's t-test, and those of the five groups divided by stroke location. The correlations between REE and the motor items of the SIAS and the FIM score were assessed with the Spearman rank correlation test. A multiple regression analysis for REE was conducted. The average body weight (BW) was 57.1 ± 11.3 kg. The average body mass index (BMI) was 22.5 ± 4.0. The mean REE (%HB) was 1,271 ± 284 kcal/day (106.0 ± 17.3%). REE and %HB of the low ADL group was less than that of the high ADL group (p < 0.05). The REE had a positive correlation with the FIM score (rs = 0.51, p < 0.01). The motor items of the SIAS were not significantly correlated with REE. BW, FIM, and stroke location were independent predictors of REE. Analysis of energy expenditure suggests that stroke patients are not hypermetabolic during the subacute phase. The 'stress factor' in stroke patients during the subacute phase was 1.0-1.1. This finding provides important information for improving nutritional management during the subacute phase in patients with stroke. © 2015 S. Karger AG, Basel.

The prediction of resting energy expenditure in type 2 diabetes mellitus is improved by factoring for glycemia.

PubMed

Gougeon, R; Lamarche, M; Yale, J-F; Venuta, T

2002-12-01

Predictive equations have been reported to overestimate resting energy expenditure (REE) for obese persons. The presence of hyperglycemia results in elevated REE in obese persons with type 2 diabetes, and its effect on the validity of these equations is unknown. We tested whether (1) indicators of diabetes control were independent associates of REE in type 2 diabetes and (2) their inclusion would improve predictive equations. A cross-sectional study of 65 (25 men, 40 women) obese type 2 diabetic subjects. Variables measured were: REE by ventilated-hood indirect calorimetry, body composition by bioimpedance analysis, body circumferences, fasting plasma glucose (FPG) and hemoglobin A(1c). Data were analyzed using stepwise multiple linear regression. REE, corrected for weight, fat-free mass, age and gender, was significantly greater with FPG>10 mmol/l (P=0.017) and correlated with FPG (P=0.013) and hemoglobin A(1c) as percentage upper limit of normal (P=0.02). Weight was the main determinant of REE. Together with hip circumference and FPG, it explained 81% of the variation. FPG improved the predictability of the equation by >3%. With poor glycemic control, it can represent an increase in REE of up to 8%. Our data indicate that in a population of obese subjects with type 2 diabetes mellitus, REE is better predicted when fasting plasma glucose is included as a variable.

Geochemistry of the rare earth elements in ferromanganese nodules from DOMES Site A, northern equatorial Pacific

USGS Publications Warehouse

Calvert, S.E.; Piper, D.Z.; Baedecker, P.A.

1987-01-01

The distribution of rare earth elements (REE) in ferromanganese nodules from DOMES Site A has been determined by instrumental neutron activation methods. The concentrations of the REE vary markedly. Low concentrations characterize samples from a depression (the valley), in which Quaternary sediments are thin or absent; high concentrations are found in samples from the surrounding abyssal hills (the highlands) where the Quaternary sediment section is relatively thick. Moreover, the valley nodules are strongly depleted in the light trivalent REE (LREE) and Ce compared with nodules from the highlands, some of the former showing negative Ce anomalies. The REE abundances in the nodules are strongly influenced by the REE abundances in coexisting bottom water. Some controls on the REE chemistry of bottom waters include: a) the more effective removal of the LREE relative to the HREE from seawater because of the greater degree of complexation of the latter elements with seawater ligands, b) the very efficient oxidative scavenging of Ce on particle surfaces in seawater, and c) the strong depletion of both Ce and the LREE in, or a larger benthic flux of the HREE into, the Antarctic Bottom Water (AABW) which flows through the valley. The distinctive REE chemistry of valley nodules is a function of their growth from geochemically evolved AABW. In contrast, the REE chemistry of highland nodules indicates growth from a local, less evolved seawater source. ?? 1987.

Rare earth elements concentration in mushroom cultivation substrates affects the production process and fruit-bodies content of Pleurotus ostreatus and Cyclocybe cylindracea.

PubMed

Koutrotsios, Georgios; Danezis, Georgios P; Georgiou, Constantinos A; Zervakis, Georgios I

2018-04-20

Concentrations of 16 rare earth elements (REEs) and two actinides were determined for the first time both in cultivated mushrooms and in their production substrates by inductively coupled plasma mass spectroscopy. Moreover, the effect of REEs on cultivation parameters and composition of the final product was assessed, together with their potential use for authentication purposes. The concentrations of REEs varied greatly among seven cultivation substrates and correlated with measurements in Cyclocybe cylindracea mushrooms; no such correlation was established in Pleurotus ostreatus. Reduction of hemicellulose, cellulose, and lignin in substrates during P. ostreatus cultivation was positively correlated with REE concentrations, which also affected the production performance depending on the species examined. In all cases, a negative correlation was established between bioconcentration factors (BCF) in mushrooms and REE content in substrates, while the effect of substrate composition on BCF values varied according to the element studied. The estimated daily intake values of REEs through mushroom consumption was at much lower levels than those reported as potentially harmful for human health. The content of REEs in cultivation substrates and in mushrooms revealed that the bioaccumulation of elements differed in each fungus. The nature/origin of substrates seemed to affect the concentration of REEs in mushrooms to a considerable extent. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Levels of rare earth elements, heavy metals and uranium in a population living in Baiyun Obo, Inner Mongolia, China: a pilot study.

PubMed

Hao, Zhe; Li, Yonghua; Li, Hairong; Wei, Binggan; Liao, Xiaoyong; Liang, Tao; Yu, Jiangping

2015-06-01

The Baiyun Obo deposit is the world's largest rare earth elements (REE) deposit. We aimed to investigate levels of REE, heavy metals (HMs) and uranium (U) based on morning urine samples in a population in Baiyun Obo and to assess the possible influence of rare earth mining processes on human exposure. In the mining area, elevated levels were found for the sum of the concentrations of light REE (LREE) and heavy REE (HREE) with mean values at 3.453 and 1.151 μg g(-1) creatinine, which were significantly higher than those in the control area. Concentrations of HMs and U in the population increased concomitantly with increasing REE levels. The results revealed that besides REE, HMs and U were produced with REE exploitation. Gender, age, educational level, alcohol and smoking habit were major factors contributing to inter-individual variation. Males were more exposed to these metals than females. Concentrations in people in the senior age group and those with only primary education were low. Drinking and smoking were associated with the levels of LREE, Cr, Cu, Cd and Pb in morning urine. Hence this study provides basic and useful information when addressing public and environmental health challenges in the areas where REE are mined and processed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Interaction of rare earth elements and components of the Horonobe deep groundwater.

PubMed

Kirishima, Akira; Kuno, Atsushi; Amamiya, Hiroshi; Kubota, Takumi; Kimuro, Shingo; Amano, Yuki; Miyakawa, Kazuya; Iwatsuki, Teruki; Mizuno, Takashi; Sasaki, Takayuki; Sato, Nobuaki

2017-02-01

To better understand the migration behavior of minor actinides in deep groundwater, the interactions between doped rare earth elements (REEs) and components of Horonobe deep groundwater were investigated. Approximately 10 ppb of the REEs, i.e. Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb were doped into a groundwater sample collected from a packed section in a borehole drilled at 140 m depth in the experiment drift of Horonobe Underground Research Laboratory in Hokkaido, Japan. The groundwater sample was sequentially filtered with a 0.2 μm pore filter, and 10 kDa, 3 kDa and 1 kDa nominal molecular weight limit (NMWL) ultrafilters with conditions kept inert. Next, the filtrate solutions were analyzed with inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of the REEs retained in solution at each filtration step, while the used filters were analyzed through neutron activation analysis (NAA) and TOF-SIMS element mapping to determine the amounts and chemical species of the trapped fractions of REEs on each filter. A strong relationship between the ratios of REEs retained in the filtrate solutions and the ionic radii of the associated REEs was observed; i.e. smaller REEs occur in larger proportions dissolved in the solution phase under the conditions of the Horonobe groundwater. The NAA and TOF-SIMS analyses revealed that portions of the REEs were trapped by the 0.2 μm pore filter as REE phosphates, which correspond to the species predicted to be predominant by chemical equilibrium calculations for the conditions of the Horonobe groundwater. Additionally, small portions of colloidal REEs were trapped by the 10 kDa and 3 kDa NMWL ultrafilters. These results suggest that phosphate anions play an important role in the chemical behavior of REEs in saline (seawater-based) groundwater, which may be useful for predicting the migration behavior of trivalent actinides released from radioactive waste repositories in the far future. Copyright © 2016 Elsevier Ltd. All rights reserved.

Typical aqueous rare earth element behavior in co-produced Brines, Wyoming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nye, Charles; Quillinan, Scott; McLing, Travis

Normalization of Rare Earth Elements (REEs) is important to remove the distracting effects of the Oddo–Harkins rule and provide a meaningful baseline. Normalizations for rocks are well developed and include chondritic meteorites, UCC, PM, PAAS, and NASC. However normalizations for aqueous REEs are limited to oceanic regions such as the North Pacific Deep Water or North Atlantic Surface Water. This leaves water in contact with continental lithologies without a suitable normalization. We present a preliminary continental aqueous REE normalization derived from 38 deep basin hydrocarbon brines in Wyoming. The REEs in these waters are seven orders of magnitude more dilutemore » than NASC but with significant europium enrichment. Gromet 1984 reports NASC Eu/Eu* is 0.2179, whereas in the normalization offered here, Eu/Eu* is 3.868. These waters also are free from the distracting reduction-oxidation cerium behavior found in ocean normalizations. Because these samples exhibit both the uniform behavior of NASC and the absolute concentration of seawater, a normalization based upon them offers a unique combination of the advantages of both. We used single-peak gaussian analysis to quantify the mean values for each REE and estimate the distribution variability. Additional sample collection during the last year revealed that the Powder River Basin (PRB) is atypical relative to the other sampled basins of Wyoming. Those other basins are the Wind River Basin (WRB) Green River Basin (GRB) and Wamsutter Area (WA). A pre-normalization gadolinium anomaly (Gd/Gd*) of between 4 and 23 with a mean of 11.5, defines the PRB samples. Other basins in this study range from 1 to 7 with a mean of 2.8. Finally, we present a preliminary model for ligand-based behavior of REEs in these samples. This model identifies bicarbonate, bromide, and chloride as forming significant complexes with REEs contributing to REE solubility. The ligand model explains observed REEs in the sampled Cretaceous and Paleocene clastic reservoirs. However, the presence of more REEs than predicted in six samples suggests that there is an additional, unconsidered ligand contributing to REE dissolution. Further work will identify this ligand, which appears to be confined to calcium-cemented and dolostone systems.« less

Surface patterning of GaAs under irradiation with very heavy polyatomic Au ions

NASA Astrophysics Data System (ADS)

Bischoff, L.; Böttger, R.; Heinig, K.-H.; Facsko, S.; Pilz, W.

2014-08-01

Self-organization of surface patterns on GaAs under irradiation with heavy polyatomic Au ions has been observed. The patterns depend on the ion mass, and the substrate temperature as well as the incidence angle of the ions. At room temperature, under normal incidence the surface remains flat, whereas above 200 °C nanodroplets of Ga appear after irradiation with monatomic, biatomic as well as triatomic Au ions of kinetic energies in the range of 10-30 keV per atom. In the intermediate temperature range of 100-200 °C meander- and dot-like patterns form, which are not related to Ga excess. Under oblique ion incidence up to 45° from the surface normal, at room temperature the surface remains flat for mon- and polyatomic Au ions. For bi- and triatomic ions in the range of 60° ≤ α ≤ 70° ripple patterns have been found, which become shingle-like for α ≥ 80°, whereas the surface remains flat for monatomic ions.

On the properties of organic heterostructures prepared with nano-patterned metallic electrode

NASA Astrophysics Data System (ADS)

Breazu, C.; Socol, M.; Preda, N.; Matei, E.; Rasoga, O.; Girtan, M.; Mallet, R.; Stanculescu, F.; Stanculescu, A.

2018-06-01

This paper presents a comparative study between the properties of the heterostructures realized with single/multi layer organic (zinc phthalocyanine or/and fullerene) prepared on Si substrate between flat or patterned aluminum (Al) layer metallic electrode and multi layer ZnO/Au/ZnO transparent conductor electrode (TCE). The UV-Nanoimprint Lithography was used for the realization of a 2D array of nanostructures (holes/pillars) characterized by a periodicity of 1.1 μm and cylindrical shape: diameter = 400 nm and depth/height = 300 nm. The effect of the electrode patterning on the properties of the organic heterostructures was analyzed. For the samples with patterned Al electrode was remarked a slight red shift of the peaks in the reflection spectra determined by an increased interaction between the organic molecules in the delimited region of the patterned holes. The shape of the emission spectra at excitation with UV light showed a narrow intense peak around 500 nm associated with the intense resonance phenomena between the energy of the incident light and the surface plasmons in the patterned Al layer. The TCE followed the morphology of the organic film on which it was deposited. The significant differences between the morphology of the top layer in the heterostructures realized on flat and patterned Al are correlated with the total thickness of the successively deposited layers and with the particularities of the molecular arrangement, leading to the preservation or deleting of patterning. An injection contact behavior was evidence for most heterostructures built on flat and patterned Al. The slight increase in current at an applied bias <1 V in the heterostructure Si/Al/ZnPc/TCE is attributed to the larger interfacial area between the patterned Al electrode and ZnPc layer compared to the interface area between flat Al and ZnPc. A buffer layer of 1,4,5,8-naphthalen-tetracarboxylic dianhydride (NTCDA), sandwiched between the flat metallic electrode and organic film in the heterostructure Si/Al/C60/ZnPc/TCE has determined an increase in the current at low applied voltages.

Sedimentary provenance of Maastrichtian oil shales, Central Eastern Desert, Egypt

NASA Astrophysics Data System (ADS)

Fathy, Douaa; Wagreich, Michael; Mohamed, Ramadan S.; Zaki, Rafat

2017-04-01

Maastrichtian oil shales are distributed within the Central Eastern Desert in Egypt. In this study elemental geochemical data have been applied to investigate the probable provenance of the sedimentary detrital material of the Maastrichtian oil shale beds within the Duwi and the Dakhla formations. The Maastrichtian oil shales are characterized by the enrichment in Ca, P, Mo, Ni, Zn, U, Cr and Sr versus post-Archean Australian shales (PAAS). The chondrite-normalized patterns of the Maastrichtian oil shale samples are showing LREE enrichment, HREE depletion, slightly negative Eu anomaly, no obvious Ce anomaly and typical shale-like PAAS-normalized patterns. The total REE well correlated with Si, Al, Fe, K and Ti, suggesting that the REE of the Maastrichtian oil shales are derived from terrigenous source. Chemical weathering indices such as Chemical Index of Alteration (CIA), Chemical Proxy of Alteration (CPA) and Plagioclase Index of Alteration (PIA) indicate moderate to strong chemical weathering. We suggest that the Maastrichtian oil shale is mainly derived from first cycle rocks especially intermediate rocks without any significant inputs from recycled or mature sources. The proposed data illustrated the impact of the parent material composition on evolution of oil shale chemistry. Furthermore, the paleo-tectonic setting of the detrital source rocks for the Maastrichtian oil shale is probably related to Proterozoic continental island arcs

Chemical and Sr isotopic characterization of North America uranium ores: Nuclear forensic applications

DOE PAGES

Balboni, Enrica; Jones, Nina; Spano, Tyler; ...

2016-08-31

This study reports major, minor, and trace element data and Sr isotope ratios for 11 uranium ore (uraninite, UO 2+x) samples and one processed uranium ore concentrate (UOC) from various U.S. deposits. The uraninite investigated represent ores formed via different modes of mineralization (e.g., high- and low-temperature) and within various geological contexts, which include magmatic pegmatites, metamorphic rocks, sandstone-hosted, and roll front deposits. In situ trace element data obtained by laser ablation-ICP-MS and bulk sample Sr isotopic ratios for uraninite samples investigated here indicate distinct signatures that are highly dependent on the mode of mineralization and host rock geology. Relativemore » to their high-temperature counterparts, low-temperature uranium ores record high U/Th ratios (>1000), low total rare earth element (REE) abundances (<1 wt%), high contents (>300 ppm) of first row transition metals (Sc, Ti, V, Cr, Mn, Co, Ni), and radiogenic 87Sr/ 86Sr ratios (>0.7200). Comparison of chondrite normalized REE patterns between uraninite and corresponding processed UOC from the same locality indicates identical patterns at different absolute concentrations. Lastly, this result ultimately confirms the importance of establishing geochemical signatures of raw, uranium ore materials for attribution purposes in the forensic analysis of intercepted nuclear materials.« less

Chemical and Sr isotopic characterization of North America uranium ores: Nuclear forensic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balboni, Enrica; Jones, Nina; Spano, Tyler

This study reports major, minor, and trace element data and Sr isotope ratios for 11 uranium ore (uraninite, UO 2+x) samples and one processed uranium ore concentrate (UOC) from various U.S. deposits. The uraninite investigated represent ores formed via different modes of mineralization (e.g., high- and low-temperature) and within various geological contexts, which include magmatic pegmatites, metamorphic rocks, sandstone-hosted, and roll front deposits. In situ trace element data obtained by laser ablation-ICP-MS and bulk sample Sr isotopic ratios for uraninite samples investigated here indicate distinct signatures that are highly dependent on the mode of mineralization and host rock geology. Relativemore » to their high-temperature counterparts, low-temperature uranium ores record high U/Th ratios (>1000), low total rare earth element (REE) abundances (<1 wt%), high contents (>300 ppm) of first row transition metals (Sc, Ti, V, Cr, Mn, Co, Ni), and radiogenic 87Sr/ 86Sr ratios (>0.7200). Comparison of chondrite normalized REE patterns between uraninite and corresponding processed UOC from the same locality indicates identical patterns at different absolute concentrations. Lastly, this result ultimately confirms the importance of establishing geochemical signatures of raw, uranium ore materials for attribution purposes in the forensic analysis of intercepted nuclear materials.« less

Sedimentary Facies Mapping Based on Tidal Channel Network and Topographic Features

NASA Astrophysics Data System (ADS)

Ryu, J. H.; Lee, Y. K.; Kim, K.; Kim, B.

2015-12-01

Tidal flats on the west coast of Korea suffer intensive changes in their surface sedimentary facies as a result of the influence of natural and artificial changes. Spatial relationships between surface sedimentary facies distribution and benthic environments were estimated for the open-type Ganghwa tidal flat and semi closed-type Hwangdo tidal flat, Korea. In this study, we standardized the surface sedimentary facies and tidal channel index of the channel density, distance, thickness and order. To extract tidal channel information, we used remotely sensed data, such as those from the Korea Multi-Purpose Satellite (KOMPSAT)-2, KOMPSAT-3, and aerial photographs. Surface sedimentary facies maps were generated based on field data using an interpolation method.The tidal channels in each sediment facies had relatively constant meandering patterns, but the density and complexity were distinguishable. The second fractal dimension was 1.7-1.8 in the mud flat, about 1.4 in the mixed flat, and about 1.3 in the sand flat. The channel density was 0.03-0.06 m/m2 in the mud flat and less than 0.02 m/m2 in the mixed and sand flat areas of the two test areas. Low values of the tidal channel index, which indicated a simple pattern of tidal channel distribution, were identified at areas having low elevation and coarse-grained sediments. By contrast, high values of the tidal channel index, which indicated a dendritic pattern of tidal channel distribution, were identified at areas having high elevation and fine-grained sediments. Surface sediment classification based on remotely sensed data must circumspectly consider an effective critical grain size, water content, local topography, and intertidal structures.

Uptake and Effects of Six Rare Earth Elements (REEs) on Selected Native and Crop Species Growing in Contaminated Soils

PubMed Central

Carpenter, David; Boutin, Céline; Allison, Jane E.; Parsons, Jessica L.; Ellis, Deanna M.

2015-01-01

Rare earth elements (REEs) have become increasingly important metals used in modern technology. Processes including mining, oil refining, discarding of obsolete equipment containing REEs, and the use of REE-containing phosphate fertilizers may increase the likelihood of environmental contamination. However, there is a scarcity of information on the toxicity and accumulation of these metals to terrestrial primary producers in contaminated soils. The objective of this work was to assess the phytotoxicity and uptake from contaminated soil of six REEs (chloride forms of praseodymium, neodymium, samarium, terbium, dysprosium, and erbium) on three native plants (Asclepias syriaca L., Desmodium canadense (L.) DC., Panicum virgatum L.) and two crop species (Raphanus sativus L., Solanum lycopersicum L.) in separate dose-response experiments under growth chamber conditions. Limited effects of REEs were found on seed germination and speed of germination. Effects on aboveground and belowground biomass were more pronounced, especially for the three native species, which were always more sensitive than the crop species tested. Inhibition concentrations (IC25 and IC50) causing 25 or 50% reductions in plant biomass respectively, were measured. For the native species, the majority of aboveground biomass IC25s (11 out of 18) fell within 100 to 300 mg REE/kg dry soil. In comparison to the native species, IC25s for the crops were always greater than 400 mg REE/kg, with the majority of results (seven out of 12) falling above 700 mg REE/kg. IC50s were often not detected for the crops. Root biomass of native species was also affected at lower doses than in crops. REE uptake by plants was higher in the belowground parts than in the above-ground plant tissues. Results also revealed that chloride may have contributed to the sensitivity of the native species, Desmodium canadense, one of the most sensitive species studied. Nevertheless, these results demonstrated that phytotoxicity may be a concern in contaminated areas. PMID:26076480

Fractionation of rare earth elements in the Mississippi River estuary and river sediments

NASA Astrophysics Data System (ADS)

Adebayo, S. B.; Johannesson, K. H.

2017-12-01

This study presents the first set of data on the fractionation of rare earth elements (REE) in the mixing zone between the Mississippi River and the Gulf of Mexico, as well as the fractionation of REE in the operationally defined fractions of Mississippi River sediments. This subject is particularly important because the Mississippi river is one of the world's major rivers, and contributes a substantial amount of water and sediment to the ocean. Hence, it is a major source of trace elements to the oceans. The geochemistry of the REE in natural systems is principally important because of their unique chemical properties, which prompt their application as tracers of mass transportation in modern and paleo-ocean environments. Another important consideration is the growth in the demand and utilization of REE in the green energy and technology industries, which has the potential to bring about a change in the background levels of these trace elements in the environment. The results of this study show a heavy REE enrichment of both the Mississippi River water and the more saline waters of the mixing zone. Our data demonstrate that coagulation and removal of REE in the low salinity region of the estuary is more pronounced among the Light REE ( 35% for Nd) compared to the Heavy REE. Remarkably, our data also indicate that REE removal in the Mississippi River estuary is significantly less than that observed in other estuaries, including the Amazon River system. We propose that the high pH/alkalinity of the Mississippi River is responsible for the greater stability of REE in the Mississippi River estuary. The results of sequential extraction of river sediments reveal different Sm/Nd ratios for the various fractions, which we submit implies different 143Nd/144Nd ratios of the labile fractions of the sediments. The possible impact of such hypothesized different Nd isotope signatures of labile fractions of the river sediments on Gulf of Mexico seawater is under investigation.

Smoking is associated with increased resting energy expenditure in the general population: The NEO study.

PubMed

Blauw, Lisanne L; Boon, Mariëtte R; Rosendaal, Frits R; de Mutsert, Renée; Gast, Karin B; van Dijk, Ko Willems; Rensen, Patrick C N; Dekkers, Olaf M

2015-11-01

Animal studies and human studies in small selected populations have shown a positive association between nicotine smoking and resting energy expenditure (REE), but data in large cohorts are lacking. We aimed to investigate the association between smoking behavior and REE in a large, population-based study. Population-based cross-sectional study. In this cross-sectional analysis of baseline measurements from the Netherlands Epidemiology of Obesity (NEO) study (n=6673), we included participants with REE measurement by indirect calorimetry who were not using lipid or glucose lowering drugs (n=1189). We used linear regression analysis to examine the association of smoking status (never, former, occasional, current smoker) and smoking quantity (pack years) with REE per kilogram (kg) fat free mass (FFM) and with REE adjusted for FFM. Models were adjusted for age, sex, ethnicity, educational level, physical activity, energy intake and body mass index (BMI). Mean (standard deviation, SD) age was 55.2 (5.9) years and BMI was 26.3 (4.4) kg/m(2). 60% of the participants were women. Mean (SD) REE/FFM (kcal/day/kg FFM) was for male never smokers 25.1 (2.0), male current smokers 26.4 (2.8), female never smokers 28.9 (2.5) and female current smokers 30.1 (3.7). After adjustment, only current smokers had a higher REE/FFM (mean difference 1.28, 95% CI 0.64, 1.92), and a higher REE adjusted for FFM (mean difference 60.3 kcal/day, 95% CI 29.1, 91.5), compared with never smokers. There was no association between pack years and REE/FFM (mean difference -0.01, 95% CI -0.06, 0.04) or REE adjusted for FFM (mean difference 0.2, 95% CI -2.4, 2.8) in current smokers. Current smoking is associated with a higher resting energy expenditure compared with never smoking in a large population-based cohort. Copyright © 2015 Elsevier Inc. All rights reserved.

Simultaneous determination of trace rare-earth elements in simulated water samples using ICP-OES with TODGA extraction/back-extraction.

PubMed

Li, FuKai; Gong, AiJun; Qiu, LiNa; Zhang, WeiWei; Li, JingRui; Liu, Yu; Liu, YuNing; Yuan, HuiTing

2017-01-01

The determination of trace rare-earth elements (REEs) can be used for the assessment of environmental pollution, and is of great significance to the study of toxicity and toxicology in animals and plants. N, N, N', N'-tetraoctyl diglycolamide (TODGA) is an environmental friendly extractant that is highly selective to REEs. In this study, an analytical method was developed for the simultaneous determination of 16 trace REEs in simulated water samples by inductively coupled plasma optical emission spectroscopy (ICP-OES). With this method, TODGA was used as the extractant to perform the liquid-liquid extraction (LLE) sample pretreatment procedure. All 16 REEs were extracted from a 3 M nitric acid medium into an organic phase by a 0.025 M TODGA petroleum ether solution. A 0.03 M ethylenediaminetetraacetic acid disodium salt (EDTA) solution was used for back-extraction to strip the REEs from the organic phase into the aqueous phase. The aqueous phase was concentrated using a vacuum rotary evaporator and the concentration of the 16 REEs was detected by ICP-OES. Under the optimum experimental conditions, the limits of detection (3σ, n = 7) for the REEs ranged from 0.0405 ng mL-1 (Nd) to 0.5038 ng mL-1 (Ho). The relative standard deviations (c = 100 ng mL-1, n = 7) were from 0.5% (Eu) to 4.0% (Tm) with a linear range of 4-1000 ng mL-1 (R2 > 0.999). The recoveries of 16 REEs ranged from 95% to 106%. The LLE-ICP-OES method established in this study has the advantages of simple operation, low detection limits, fast analysis speed and the ability to simultaneously determine 16 REEs, thereby acting as a viable alternative for the simultaneous detection of trace amounts of REEs in water samples.

Nutritional rehabilitation increases the resting energy expenditure of malnourished children with severe cerebral palsy.

PubMed

Arrowsmith, Fiona E; Allen, Jane R; Gaskin, Kevin J; Somerville, Helen; Birdsall, Jocelyn; Barzi, Federica; O'Loughlin, Edward V

2012-02-01

The aim of this study was to measure resting energy expenditure (REE) and energy intake in children with quadriplegic cerebral palsy (CP), to relate these to anthropometric measurements, and to determine the influence of nutritional rehabilitation on REE. Fifty-six children (20 females, 36 males; age range 3y 11mo-18y; mean age 10y; SD 3y 11mo) with CP (Gross Motor Function Classification System level V) participated in this cross-sectional study. Children were excluded if they had a known metabolic disorder, genetic syndrome, or chromosomal abnormality. Thirty-three of the children were tube fed and 23 were fed orally. A comparison group comprised 111 (42 females, 69 males) healthy children who had undergone anthropometric and REE measurements and were of similar age to the children with CP (4-19y). REE was measured by indirect calorimetry and energy intake was determined from weighed food records. The REE in the children with CP was low (79.5%) compared with that predicted and highly variable (SD 38.4%). Fat-free mass was the strongest predictor of REE, accounting for 27% of the variation. Energy intake as a percentage of REE in was greatly overestimated in oral-fed children with CP (293%). In a subset of children with CP (n=14), an increased energy intake by gastrostomy tube feeding resulted in an increase in REE from 70.0% to 101.9% of that predicted. The REE of children with CP is low and variable and is not strongly related to any one anthropometric measurement. Food records in oral-fed children with CP are of little value owing to their inaccuracy. This study provided support for the hypothesis that the low REE found in malnourished children with CP is partly due to a low energy intake. © The Authors. Developmental Medicine & Child Neurology © 2012 Mac Keith Press.

Simultaneous determination of trace rare-earth elements in simulated water samples using ICP-OES with TODGA extraction/back-extraction

PubMed Central

Li, FuKai; Qiu, LiNa; Zhang, WeiWei; Li, JingRui; Liu, Yu; Liu, YuNing; Yuan, HuiTing

2017-01-01

The determination of trace rare-earth elements (REEs) can be used for the assessment of environmental pollution, and is of great significance to the study of toxicity and toxicology in animals and plants. N, N, N′, N′-tetraoctyl diglycolamide (TODGA) is an environmental friendly extractant that is highly selective to REEs. In this study, an analytical method was developed for the simultaneous determination of 16 trace REEs in simulated water samples by inductively coupled plasma optical emission spectroscopy (ICP-OES). With this method, TODGA was used as the extractant to perform the liquid-liquid extraction (LLE) sample pretreatment procedure. All 16 REEs were extracted from a 3 M nitric acid medium into an organic phase by a 0.025 M TODGA petroleum ether solution. A 0.03 M ethylenediaminetetraacetic acid disodium salt (EDTA) solution was used for back-extraction to strip the REEs from the organic phase into the aqueous phase. The aqueous phase was concentrated using a vacuum rotary evaporator and the concentration of the 16 REEs was detected by ICP-OES. Under the optimum experimental conditions, the limits of detection (3σ, n = 7) for the REEs ranged from 0.0405 ng mL-1 (Nd) to 0.5038 ng mL-1 (Ho). The relative standard deviations (c = 100 ng mL-1, n = 7) were from 0.5% (Eu) to 4.0% (Tm) with a linear range of 4–1000 ng mL-1 (R2 > 0.999). The recoveries of 16 REEs ranged from 95% to 106%. The LLE-ICP-OES method established in this study has the advantages of simple operation, low detection limits, fast analysis speed and the ability to simultaneously determine 16 REEs, thereby acting as a viable alternative for the simultaneous detection of trace amounts of REEs in water samples. PMID:28945788

Uptake and Effects of Six Rare Earth Elements (REEs) on Selected Native and Crop Species Growing in Contaminated Soils.

PubMed

Carpenter, David; Boutin, Céline; Allison, Jane E; Parsons, Jessica L; Ellis, Deanna M

2015-01-01

Rare earth elements (REEs) have become increasingly important metals used in modern technology. Processes including mining, oil refining, discarding of obsolete equipment containing REEs, and the use of REE-containing phosphate fertilizers may increase the likelihood of environmental contamination. However, there is a scarcity of information on the toxicity and accumulation of these metals to terrestrial primary producers in contaminated soils. The objective of this work was to assess the phytotoxicity and uptake from contaminated soil of six REEs (chloride forms of praseodymium, neodymium, samarium, terbium, dysprosium, and erbium) on three native plants (Asclepias syriaca L., Desmodium canadense (L.) DC., Panicum virgatum L.) and two crop species (Raphanus sativus L., Solanum lycopersicum L.) in separate dose-response experiments under growth chamber conditions. Limited effects of REEs were found on seed germination and speed of germination. Effects on aboveground and belowground biomass were more pronounced, especially for the three native species, which were always more sensitive than the crop species tested. Inhibition concentrations (IC25 and IC50) causing 25 or 50% reductions in plant biomass respectively, were measured. For the native species, the majority of aboveground biomass IC25s (11 out of 18) fell within 100 to 300 mg REE/kg dry soil. In comparison to the native species, IC25s for the crops were always greater than 400 mg REE/kg, with the majority of results (seven out of 12) falling above 700 mg REE/kg. IC50s were often not detected for the crops. Root biomass of native species was also affected at lower doses than in crops. REE uptake by plants was higher in the belowground parts than in the above-ground plant tissues. Results also revealed that chloride may have contributed to the sensitivity of the native species, Desmodium canadense, one of the most sensitive species studied. Nevertheless, these results demonstrated that phytotoxicity may be a concern in contaminated areas.

Size distribution of rare earth elements in coal ash

USGS Publications Warehouse

Scott, Clinton T.; Deonarine, Amrika; Kolker, Allan; Adams, Monique; Holland, James F.

2015-01-01

Rare earth elements (REEs) are utilized in various applications that are vital to the automotive, petrochemical, medical, and information technology industries. As world demand for REEs increases, critical shortages are expected. Due to the retention of REEs during coal combustion, coal fly ash is increasingly considered a potential resource. Previous studies have demonstrated that coal fly ash is variably enriched in REEs relative to feed coal (e.g, Seredin and Dai, 2012) and that enrichment increases with decreasing size fractions (Blissett et al., 2014). In order to further explore the REE resource potential of coal ash, and determine the partitioning behavior of REE as a function of grain size, we studied whole coal and fly ash size-fractions collected from three U.S commercial-scale coal-fired generating stations burning Appalachian or Powder River Basin coal. Whole fly ash was separated into , 5 um, to 5 to 10 um and 10 to 100 um particle size fractions by mechanical shaking using trace-metal clean procedures. In these samples REE enrichments in whole fly ash ranges 5.6 to 18.5 times that of feedcoals. Partitioning results for size separates relative to whole coal and whole fly ash will also be reported. 

In-situ measurements of rare earth elements in deep sea sediments using nuclear methods.

PubMed

Obhođaš, Jasmina; Sudac, Davorin; Meric, Ilker; Pettersen, Helge E S; Uroić, Milivoj; Nađ, Karlo; Valković, Vlado

2018-03-21

The prospecting activities for finding new rare earth elements (REE) sources have increased greatly in recent years. One of the main discoveries was announced in 2011 by Japanese researchers who found large quantities of REE on the ocean seafloor at the sea depths greater than 4,000 m. The classic approach to investigate REE in deep sea sediments is to obtain sediment samples by drilling that is followed by laborious laboratory analysis. This is very expensive, time consuming and not appropriate for exploring vast areas. In order to efficiently explore the ocean floor for REE deposits, the further development of affordable sensors is needed. Here, we propose two nuclear techniques for exploring REE in surface deep sea sediments: i) Passive measurement of lutetium-176 radioactivity, appropriate if long-term in-situ measurements are possible, and ii) The use of the neutron sensor attached to a remotely operated vehicle for rapid in-situ measurement of gadolinium by thermal neutron-capture. Since concentrations of lutetium and gadolinium show strong linear correlation to the total REE concentrations in deep sea sediments, it is possible to deduce the total REE content by measuring Lu or Gd concentrations only.

A survey of 16 rare Earth elements in the major foods in China.

PubMed

Jiang, Ding Guo; Yang, Jie; Zhang, Shuo; Yang, Da Jin

2012-06-01

The aim of this survey was to investigate the level of contamination of the most consumed foods in China with 16 rare earth elements (REEs), and to provide the basic data for establishing and revising food safety standards for REEs. Sixteen REEs in foods were measured by inductively coupled plasma-mass spectrometry (ICP-MS) in the labs of the Centers for Disease Control and Prevention of four provinces and two municipalities, during 2009-2010. 1 231 samples were analyzed and 19 121 concentration data of 16 REEs were collected. The REEs levels in the investigated foods varied significantly. The concentrations of cerium (Ce), dysprosium (Dy), yttrium (Y), lanthanum (La), and neodymium (Nd) were relatively high, while the remaining eleven REEs were at low levels. The mean values of total rare earth element oxides (REOs) in cereals, fresh vegetables, fresh aquatic products, fresh meats and eggs varied from 0.052 mg/kg to 0.337 mg/kg. 16 REEs in the major foods were at very low contamination levels in the investigated regions. Copyright © 2012 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

Energy requirements in frail elderly people: a review of the literature.

PubMed

Gaillard, C; Alix, E; Sallé, A; Berrut, G; Ritz, P

2007-02-01

This review collates studies of healthy, sick, underweight (BMI < or = 21 kg/m2) and very elderly people (> or = 90 yr), in whom resting energy expenditure (REE) was measured using indirect calorimetry. We have observed the following: (1) REE, when adjusted for differences in both body weight and fat-free mass (FFM), is similar in healthy and in sick elderly people being 20 and 28 kcal/kg of FFM per day, respectively, (2) their nutritional status influences their energy requirements given that weight-adjusted REE increases in line with a decrease in BMI, (3) total energy expenditure is lower in sick elderly people given that their physical activity level, i.e. the ratio of total energy expenditure to REE, is reduced during disease averaging at 1.36, (4) energy intake (EI) being only 1.23 x REE is insufficient to cover energy requirements in sick elderly patients, whereas the EI of healthy elderly people appears sufficient to cover requirements, and finally, (5) gender ceases to be a determinant of REE in people aged 60 yr or over, with the Harris & Benedict equation capable of accurately predicting mean REE in this population, whether healthy or sick.

REE in karst bauxites: the Campania example (southern Italy)

NASA Astrophysics Data System (ADS)

Mondillo, N.; Boni, M.; Balassone, G.; Rollinson, G.

2012-04-01

Global production of Rare Earth Element (REE) has dramatically increased in the last years, hence the strong interest to identify new deposits and to understand the processes responsible for their formation. Among REE concentrations related to weathering, the current targets are represented by the ion-adsorption deposit-types, occurring in China, in which REEs are adsorbed onto the surface of clays. Laterites have been also intensively investigated since the discovery of the secondary deposit of Mount Weld (Australia). Most REEs behave as immobile elements in laterites, and tend to be enriched compared to the underlying parent rocks. Many authors debate on a possible REE fractionation along the laterite profiles, resulting in the formation of supergene LREE-minerals. Bauxites are economic Al accumulations, derived from the weathering of alumosilicate-rich parent rocks resulting in the development of laterite profiles. Components as Ca, Mg, K, Si are leached and residual Fe, Al and Ti precipitate in form of hematite>>goethite, gibbsite [Al(OH)3] or amorphous Al hydroxides and anatase. Metabauxites can contain boehmite or diaspore [AlO(OH)]. Chemical composition (including REEs content) of lateritic bauxites generally mirrors the original composition of the parent rock. Geochemistry of REEs in karst bauxites, which lay on carbonate bedrocks and may be also allochthonous to them, is not so straightforward. Cretaceous karst bauxite deposits in the Apennine chain (Southern Italy) are presently uneconomic. A full mineralogical and geochemical study has been performed on several deposits of the Campania district, and three representative profiles have been sampled. In all deposits the bauxite ore has an oolitic-pisolitic texture, but contains also detrital intervals. The mineral association consists of boehmite, kaolinite and hematite, with less goethite and anatase. The main REE-bearing mineral is detrital monazite. In detail, we could detect (SEM) other LREE-phosphates (florencite type minerals) in the Regia Piana deposit and possibly LREE-enriched goethite at Dragoni. QEMSCAN® analysis allowed the identification and location of discrete particles of monazite and xenotime, but because of their very small dimensions (typically <10 microns) it was difficult to determine the exact chemical composition without further investigation. Chemical analyses have shown a total REEs content of 620 ppm on average in all bauxite deposits, with a maximum value of 1454 ppm of total REEs at the top of the Regia Piana profile. The LREE (La-Eu) contents in the samples vary between 200 and 1400 ppm, with positive Ce and La anomalies. The HREE (Gd-Lu) contents are always around 40-60 ppm. The relationship between REEs and the Al and/or Fe values is not clear, probably because the REE content may be slightly biased by the detrital characteristics of the bauxite. The higher Ce and other LREE values, detected at the top of several deposits rather than at the bottom, can be related to LREE supergene minerals occurrence in the higher parts of profile. The Campania deposits represent an interesting case study for REE concentration in karst bauxites. A similar LREE fractionation process could be applied to other bauxite deposits, though related to more favorable parent rocks with sub-economic REE-grades.

1.5% root-mean-square flat-intensity laser beam formed using a binary-amplitude spatial light modulator.

PubMed

Liang, Jinyang; Kohn, Rudolph N; Becker, Michael F; Heinzen, Daniel J

2009-04-01

We demonstrate a digital micromirror device (DMD)-based optical system that converts a spatially noisy quasi-Gaussian to an eighth-order super-Lorentzian flat-top beam. We use an error-diffusion algorithm to design the binary pattern for the Texas Instruments DLP device. Following the DMD, a telescope with a pinhole low-pass filters the beam and scales it to the desired sized image. Experimental measurements show a 1% root-mean-square (RMS) flatness over a diameter of 0.28 mm in the center of the flat-top beam and better than 1.5% RMS flatness over its entire 1.43 mm diameter. The power conversion efficiency is 37%. We develop an alignment technique to ensure that the DMD pattern is correctly positioned on the incident beam. An interferometric measurement of the DMD surface flatness shows that phase uniformity is maintained in the output beam. Our approach is highly flexible and is able to produce not only flat-top beams with different parameters, but also any slowly varying target beam shape. It can be used to generate the homogeneous optical lattice required for Bose-Einstein condensate cold atom experiments.

Modeling and Implementation of Visibility in Programming Languages

DTIC Science & Technology

1987-12-01

Birtwistle et al. 1973] [Goldberg and Robson 1983] [Maurer 1976] [Rees et al. 1984] [Rees and Adams IV 1982] [Jones and Muchnick 1978] Table 2.1...Word and Object, MIT Press, Cambridge, 1960. REES, J. A. and ADAMS IV, N. I., "T: a dialect of LISP or, L AMBDA: the ultimate software tool...34, Conference record of the 1982 ACM symposium on USP and functional progranuning, 1982. REES, J. A., ADAMS IV, N. 1., and MEEHAN, J. R., The T man ual

FICE in Predicting Colorectal Flat Lesion Histology.

PubMed

Akarsu, Cevher; Sahbaz, Nuri A; Dural, Ahmet C; Kones, Osman; Binboga, Sinan; Kabuli, Hamit A; Gumusoglu, Alpen Y; Alis, Halil

2017-01-01

Colonoscopy is the gold standard for detection of polyps and is preventive against colorectal cancers. Flat adenomas are small, superficial lesions and have a high rate of going undetected during conventional white-light endoscopy. This article adds to the scant body of literature in English regarding in vivo detection and diagnosis of flat adenomas using Fujinon intelligent color enhancement (FICE) system. In this study, we investigated the diagnosis of flat lesions via the FICE endoscopy system and in vivo histologic diagnostic estimations of flat lesions. This prospective study was conducted in patients who underwent colonoscopy that found flat adenomas. Lesions were classified morphologically with regard to the Paris Classification and sent for histopathologic examination after in vivo histologic diagnostic estimations were made according to Kudo's pit pattern classification. The positive predictive value (PPV), negative predictive value (NPV), specificity, sensitivity, and accuracy of in vivo endoscopic diagnostic estimations of flat lesions with the FICE system were analyzed. A total of 217 flat lesions were identified in 137 patients. Of the lesions, 85.7% were Paris type 0-IIa, and 59.4% were Kudo pit pattern type III. When the FICE diagnostic estimations of flat lesions and final pathology results were considered, PPV was 68.5%, NPV value was 89.6%, sensitivity was 94.7%, specificity was 50.9%, and accuracy was 74.2%. Biologic importance of flat lesions is obscure, as they are usually missed during colonoscopy. The use of novel endoscopic techniques may improve their detection and diagnosis rates.

Dirac electrons in Moiré superlattice: From two to three dimensions

NASA Astrophysics Data System (ADS)

Hu, Chen; Michaud-Rioux, Vincent; Kong, Xianghua; Guo, Hong

2017-11-01

Moiré patterns in van der Waals (vdW) heterostructures bring novel physical effects to the materials. We report theoretical investigations of the Moiré pattern formed by graphene (Gr) on hexagonal boron nitride (h BN). For both the two-dimensional (2D) flat-sheet and the freestanding three-dimensional (3D) wavelike film geometries, the behaviors of Dirac electrons are strongly modulated by the local high-symmetry stacking configurations of the Moiré pattern. In the 2D flat sheet, the secondary Dirac cone (SDC) dispersion emerges due to the stacking-selected localization of SDC wave functions, while the original Dirac cone (ODC) gap is suppressed due to an overall effect of ODC wave functions. In the freestanding 3D wavelike Moiré structure, we predict that a specific local stacking in the Moiré superlattice is promoted at the expense of other local stackings, leading to an electronic structure more similar to that of the perfectly matching flat Gr/h BN than that of the flat-sheet 2D Moiré pattern. To capture the overall picture of the Moiré superlattice, supercells containing 12 322 atoms are simulated by first principles.

Long-term impact of the ketogenic diet on growth and resting energy expenditure in children with intractable epilepsy.

PubMed

Groleau, Veronique; Schall, Joan I; Stallings, Virginia A; Bergqvist, Christina A

2014-09-01

The long-term effects of the ketogenic diet, a high fat diet for treating intractable epilepsy, on resting energy expenditure (REE) are unknown. The aim of this study was to evaluate the impact of 15 months of ketogenic diet treatment on growth and REE in children with intractable epilepsy. Growth, body composition, and REE were assessed at baseline, 3 months and 15 months in 24 children (14 males, 10 females; mean age 5 y 6 mo [SD 26 mo], range 7 mo-6 y 5 mo), 10 with cerebral palsy [CP]). Fifteen were identified as ketogenic diet responders at 3 months and continued on the ketogenic diet until 15 months. These were compared to 75 healthy children (43 males, 32 females; mean age 6 y 3 mo [SD 21 mo] age range 2-9 y). REE was expressed as percentage predicted, growth as height (HAz) and weight (WAz) z-scores, and body composition as fat and fat free mass (FFM). HAz declined -0.2 and -0.6 from baseline to 3 months and 15 months respectively (p = 0.001), while WAz was unchanged. In ketogenic diet responders, FFM, age and CP diagnosis predicted REE (overall R(2) = 0.76, p<0.001) and REE did not change. REE adjusted for FFM was lower (p<0.01) in children with CP at baseline (mean [standard error], -143[51] kcals/d) and 15 months (-198[53] kcals/d) compared to the healthy children. After 15 months of the ketogenic diet, linear growth status declined while weight status and REE were unchanged. REE remained reduced in children with CP. © 2014 Mac Keith Press.

Long-term impact of the ketogenic diet on growth and resting energy expenditure in children with intractable epilepsy

PubMed Central

GROLEAU, VERONIQUE; SCHALL, JOAN I; STALLINGS, VIRGINIA A; BERGQVIST, CHRISTINA A

2014-01-01

AIM The long-term effects of the ketogenic diet, a high fat diet for treating intractable epilepsy, on resting energy expenditure (REE) are unknown. The aim of this study was to evaluate the impact of 15 months of ketogenic diet treatment on growth and REE in children with intractable epilepsy. METHOD Growth, body composition and REE were assessed at baseline, 3 and 15 months in 24 children (14 males, 10 females; mean age 5y 6mo (SD 26mo), range 7mo–6y 5mo), 10 with cerebral palsy [CP]). Fifteen were identified as ketogenic diet responders at 3 months and continued on the ketogenic diet until 15 months. These were compared to 75 healthy children (43 males, 32 females; mean age 6y 3mo [SD 21mo] age range 2–9y). REE was expressed as percentage predicted, growth as height (HAz) and weight (WAz) z-scores, and body composition as fat and fat free mass (FFM). RESULTS HAz declined −0.2 and −0.6 from baseline to 3 and 15 months, respectively (p=0.001), while WAz was unchanged. In ketogenic diet responders, FFM, age and CP diagnosis predicted REE (overall R2=0.76, p<0.001) and REE did not change. REE adjusted for FFM was lower (p<0.01) in children with CP at baseline (mean [standard error], −143[51] kcals/d) and 15 months (−198[53] kcals/d) compared to the healthy children. INTERPRETATION After 15 months of the ketogenic diet, linear growth status declined while weight status and REE were unchanged. REE remained reduced in children with CP. PMID:24749520

Enhanced separation of rare earth elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyon, K.; Greenhalgh, M.; Herbst, R. S.

2016-09-01

Industrial rare earth separation processes utilize PC88A, a phosphonic acid ligand, for solvent extraction separations. The separation factors of the individual rare earths, the equipment requirements, and chemical usage for these flowsheets are well characterized. Alternative ligands such as Cyanex® 572 and the associated flowsheets are being investigated at the pilot scale level to determine if significant improvements to the current separation processes can be realized. These improvements are identified as higher separation factors, reduced stage requirements, or reduced chemical consumption. Any of these improvements can significantly affect the costs associated with these challenging separation proccesses. A mid/heavy rare earthmore » element (REE) separations flowsheet was developed and tested for each ligand in a 30 stage mixer-settler circuit to compare the separation performance of PC88A and Cyanex® 572. The ligand-metal complex strength of Cyanex® 572 provides efficient extraction of REE while significantly reducing the strip acid requirements. Reductions in chemical consumption have a significant impact on process economics for REE separations. Partitioning results summarized Table 1 indicate that Cyanex® 572 offers the same separation performance as PC88A while reducing acid consumption by 30% in the strip section for the mid/heavy REE separation. Flowsheet Effluent Compositions PC88A Cyanex® 572 Raffinate Mid REE Heavy REE 99.40% 0.60% 99.40% 0.60% Rich Mid REE Heavy REE 2.20% 97.80% 0.80% 99.20% Liquor Strip Acid Required 3.4 M 2.3 M Table 1 – Flowsheet results comparing separation performance of PC88A and Cyanex® 572 for a mid/heavy REE separation.« less

Estimating the Submarine Groundwater Discharge Flux of Rare Earth Elements to the Indian River Lagoon, Fl, USA, Using the 1-D Vertical - Flow Equation

NASA Astrophysics Data System (ADS)

Chevis, D. A.; Johannesson, K. H.; Burdige, D.; Cable, J. E.; Martin, J. B.

2013-12-01

Understanding the sources and sinks of trace elements like the rare earth elements (REE) in the oceans has important implications for quantifying their global geochemical cycles, their application as paleoceanographic tracers, and in discerning the geochemical reactions that mobilize, sequester, and fractionate REEs in the environment. This understanding is critical for neodymium (Nd) because radiogenic Nd isotopes are commonly used in paleoceanographic studies over glacial-interglacial to million year time scales. The submarine groundwater discharge (SGD) flux of each REE for the Indian River Lagoon, Fl, USA, was calculated using a modified form of the 1-dimensional vertical-flow equation that accounts for diffusion, advection, and non-local mass transfer processes. The SGD REE flux is comprised of two sources: a near shore, heavy REE (HREE) enriched advective source chiefly composed of terrestrial SGD, and a light REE (LREE) and middle REE (MREE) enriched source that originates from reductive dissolution of Fe (III) oxides/hydroxides in the subterranean estuary. This SGD flux mixture of REE sources is subsequently transported by groundwater seepage and bioirrigation to the overlying lagoon water column. The total SGD flux of REEs reveals that the subterranean estuary of the Indian River Lagoon is a source for LREE and MREEs, and a sink for the HREEs, to the local coastal ocean. The calculated SGD flux of Nd presented in this study is estimated at 7.69×1.02 mmol/day, which is roughly equivalent to the effective local river flux to the Indian River Lagoon. Although our re-evaluated SGD flux of Nd to the Indian River Lagoon is lower than estimates in our previous work, it nonetheless represents a substantial input to the coastal ocean.

Deciphering human-climate interactions in an ombrotrophic peat record: REE, Nd and Pb isotope signatures of dust supplies over the last 2500 years (Misten bog, Belgium)

NASA Astrophysics Data System (ADS)

Fagel, N.; Allan, M.; Le Roux, G.; Mattielli, N.; Piotrowska, N.; Sikorski, J.

2014-06-01

A high-resolution peat record from Eastern Belgium reveals the chronology of dust deposition for the last 2500 years. REE and lithogenic elements in addition to Nd and Pb isotopes were measured in a 173 cm age-dated peat profile and provide a continuous chronology of dust source and intensity. Calculated dust flux show pronounced increases c. 300 BC, 600 AD, 1000 AD, 1200 AD and from 1700 AD, corresponding to local and regional human activities combined with climate change. The Industrial Revolution samples (1700-1950 AD) are characterised by a significant enrichment in Sc-normalised REE abundance (sum REE/Sc > 25) due to intensive coal combustion. For the pre-Industrial Revolution samples, the Sc-normalised REE abundance (10 < Sum REE/Sc < 25) and the εNd variability (-13 to -9) are interpreted by a mixing between dust particles from local soils and long-range transport of desert particles. Three periods characterised by dominant-distal sources (c. 320 AD, 1000 AD and 1700 AD) are consistent with local wetter-than-average intervals as indicated by a lower degree of peat humification. Local erosion prevails during the drier (higher humification) intervals (100 AD, 600 AD). On a global scale, more distal supplies are driven during colder periods, in particular during the Oort and Maunder minima, suggesting a potential link between dust deposition and global climate. Combining REE abundance, fractionation between Light REE and Heavy REE and Nd isotope data in ombrotrophic peat allows one to distinguish between dust flux changes related to human and climate forcings.

Comparison of estimates of resting energy expenditure equations in haemodialysis patients.

PubMed

Hung, Rachel; Sridharan, Sivakumar; Farrington, Ken; Davenport, Andrew

2017-04-21

Waste products of metabolism accumulate in patients with chronic kidney disease, and require clearance by haemodialysis (HD). We wished to determine whether there was an association between resting energy expenditure (REE) and total energy expenditure (TEE) in HD patients and body composition. We determined REE by recently validated equations (CKD equation) and compared REE with that estimated by standard equations for REE, and TEE calculated from patient reported physical activity, in HD patients with corresponding body composition measured by dual energy X-ray absorptiometry (DEXA) scanning. We studied 107 patients, 69 male (64.5%), mean age 62.7 ± 15.1 years. The CKD equation REE was 72.5 ± 13.3 watts (W) and TEE 83.2 ± 9.7 W. There was a strong association between REE with body surface area (BSA) (r2 = 0.80), total soft lean and fat lean tissue mass (r2 = 0.69), body mass index (BMI) (r2 = 0.34), all p<0.001. REE estimated using the modified Harris Benedict, Mifflin St. Jeor, Katch McArdle, Bernstein and Robertson equations underestimated REE compared to the CKD equation. TEE was more strongly associated with BSA (r2 = 0.51), appendicular muscle mass (r2 = 0.42), than BMI (r2 = 0.15) all p<0.001.TEE was greater for those employed (104.9 ± 10.7 vs. 83.1 ± 12.3 W, p<0.001), and with no co-morbidity (88.7 ± 14.8 vs. 82.7 ± 12.3 W, p<0.05). Standard equations underestimate REE in HD patients compared to the CKD equation. TEE was greater in those with more skeletal muscle mass, in those who were employed and in those with the least co-morbidity. More metabolically active patients may well require greater dialytic clearances.

Post-magmatic solid solutions of CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and REE-bearing epidote in miarolitic pegmatites of Permian Baveno granite (Verbania, central-southern alps, Italy)

NASA Astrophysics Data System (ADS)

Guastoni, Alessandro; Nestola, Fabrizio; Schiazza, Mariangela

2017-06-01

CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and rare earth element (REE)-bearing epidote occur as globular aggregates and platy prismatic crystals in miarolitic cavities in a niobium, yttrium, fluorine (NYF) granitic pegmatite at Baveno, Verbania, Southern Alps, Italy. These samples were investigated by means of an electron probe micro-analyser (EPMA) and single-crystal X-ray diffraction. Our EPMA results show that the globular aggregates have the highest REE content in the core portion and decreases to REE-bearing epidote towards the rim whereas the prismatic crystals are characterized by marked oscillatory zoning that have the highest REE contents at the rim of the crystal. The unit-cell parameters of "allanites" have an intermediate unit-cell between CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and REE-free epidote, because reflect the strong chemical heterogeneity of the samples which form complete solid solutions. Hydrothermal fluids control the activity and precipitation of incompatible elements like high field strength elements (HFSE), Sc and REE by hydrous F-rich fluids below the critical temperature which allow to deposit accessory minerals in the cavities with decreasing temperature. The source of REE and Y are the sheet and REE-silicates like siderophyllite-annite, and gadolinite-(Y) which underwent partial to complete decomposition by the activity of aggressive F-rich hydrothermal fluids.

The relationship between resting energy expenditure and weight loss in benign and malignant disease.

PubMed Central

Hansell, D T; Davies, J W; Burns, H J

1986-01-01

The relationship between cancer, weight loss, and resting energy expenditure (REE) has been investigated in 136 patients using indirect calorimetry. Ninety-one patients had gastric, colorectal, or nonsmall cell bronchial neoplasm, seven patients had other malignancies, and 38 patients had nonmalignant illness. Four groups were studied: weight stable cancer patients (CWS: N = 56), weight losing cancer patients (CWL: N = 42), weight stable patients with nonmalignant illness (NCWS: N = 22), and weight losing patients with nonmalignant illness (NCWL: N = 16). In each group REE correlated significantly with body weight, metabolic body size, and lean body mass (LBM: estimated from total body water measurements). The closest correlation was between REE and lean body mass, with the slope of the CWL regression line differing significantly from that of the CWS (p less than 0.05) and NCWS (p less than 0.02) groups. However, there was no difference in REE expressed as kcal/kg LBM/d between the groups. The slopes of the regressions between REE and LBM were almost identical when all cancer patients were compared with all patients with nonmalignant illness. However, when all weight stable patients were compared with all weight losing patients, there was a highly significant difference between the slopes of the regressions (p less than 0.005). This indicates that the weight losing state rather than the presence or absence of cancer is responsible for an alteration in the relationship between REE and LBM. There were no differences in REE between the different tumor types. It is concluded that REE is not elevated in patients with gastric, colorectal, or nonsmall cell bronchial cancer. Elevation of REE contributes very little to the etiology of cancer cachexia. PMID:3082302

RNA sequencing confirms similarities between PPI-responsive oesophageal eosinophilia and eosinophilic oesophagitis.

PubMed

Peterson, K A; Yoshigi, M; Hazel, M W; Delker, D A; Lin, E; Krishnamurthy, C; Consiglio, N; Robson, J; Yandell, M; Clayton, F

2018-06-04

Although current American guidelines distinguish proton pump inhibitor-responsive oesophageal eosinophilia (PPI-REE) from eosinophilic oesophagitis (EoE), these entities are broadly similar. While two microarray studies showed that they have similar transcriptomes, more extensive RNA sequencing studies have not been done previously. To determine whether RNA sequencing identifies genetic markers distinguishing PPI-REE from EoE. We retrospectively examined 13 PPI-REE and 14 EoE biopsies, matched for tissue eosinophil content, and 14 normal controls. Patients and controls were not PPI-treated at the time of biopsy. We did RNA sequencing on formalin-fixed, paraffin-embedded tissue, with differential expression confirmation by quantitative polymerase chain reaction (PCR). We validated the use of formalin-fixed, paraffin-embedded vs RNAlater-preserved tissue, and compared our formalin-fixed, paraffin-embedded EoE results to a prior EoE study. By RNA sequencing, no genes were differentially expressed between the EoE and PPI-REE groups at the false discovery rate (FDR) ≤0.01 level. Compared to normal controls, 1996 genes were differentially expressed in the PPI-REE group and 1306 genes in the EoE group. By less stringent criteria, only MAPK8IP2 was differentially expressed between PPI-REE and EoE (FDR = 0.029, 2.2-fold less in EoE than in PPI-REE), with similar results by PCR. KCNJ2, which was differentially expressed in a prior study, was similar in the EoE and PPI-REE groups by both RNA sequencing and real-time PCR. Eosinophilic oesophagitis and PPI-REE have comparable transcriptomes, confirming that they are part of the same disease continuum. © 2018 John Wiley & Sons Ltd.

Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

PubMed Central

2014-01-01

To provide a front transparent electrode for use in highly efficient hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, porous flat layer and micro-patterns of zinc oxide (ZnO) nanoparticle (NP) layers were prepared through ultraviolet nanoimprint lithography (UV-NIL) and deposited on Al-doped ZnO (AZO) layers. Through this, it was found that a porous micro-pattern of ZnO NPs dispersed in resin can optimize the light-trapping pattern, with the efficiency of solar cells based on patterned or flat mesoporous ZnO layers increased by 27% and 12%, respectively. PMID:25276101