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Sample records for earth element geochemistry

  1. The lherzolitic shergottite Grove Mountains 99027: Rare earth element geochemistry

    NASA Astrophysics Data System (ADS)

    Hsu, Weibiao; Guan, Yunbin; Wang, Henian; Leshin, Laurie A.; Wang, Rucheng; Zhang, Wenlan; Chen, Xiaoming; Zhang, Fusheng; Lin, Chengyi

    2004-05-01

    We report here on an ion probe study of rare earth element (REE) geochemistry in the lherzolitic shergottite Grove Mountains (GRV) 99027. This meteorite shows almost identical mineralogy, petrology, and REE geochemistry to those of the lherzolitic shergottites Allan Hills (ALH) A77005, Lewis Cliff (LEW) 88516, and Yamato (Y-) 793605. REE concentrations in olivine, pyroxenes, maskelynite, merrillite, and melt glass are basically comparable to previous data obtained from ALH A77005, LEW 88516, and Y-793605. Olivine is the dominant phase in this meteorite. It is commonly enclosed by large (up to several mm) pigeonite oikocrysts. Non-poikilitic areas consist of larger olivine grains (~mm), pigeonite, augite, and maskelynite. Minor merrillite (up to 150 mm in size) is widespread in non-poikilitic regions, occurring interstitially between olivine and pyroxene grains. It is the main REE carrier in GRV 99027 and has relatively higher REEs (200-1000 Å CI) than that of other lherzolitic shergottites. A REE budget calculation for GRV 99027 yields a whole rock REE pattern very similar to that of other lherzolites. It is characterized by the distinctive light REE depletion and a smooth increase from light REEs to heavy REEs. REE microdistributions in GRV 99027 strongly support the idea that all lherzolitic shergottites formed by identical igneous processes, probably from the same magma chamber on Mars. Despite many similarities in mineralogy, petrography, and trace element geochemistry, subtle differences exist between GRV 99027 and other lherzolitic shergottites. GRV 99027 has relatively uniform mineral compositions (both major elements and REEs), implying that it suffered a higher degree of sub-solidus equilibration than the other three lherzolites. It is notable that GRV 99027 has experienced terrestrial weathering in the Antarctic environment, as its olivine and pyroxenes commonly display a light REE enrichment and a negative Ce anomaly. Caution needs to be taken in future chronological studies.

  2. The geochemistry of rare earth elements in the Amazon River estuary

    SciTech Connect

    Shokovitz, E.R. )

    1993-05-01

    The estuarine geochemistry of rare earth elements (REEs) was studied using samples collected in the Amazon River estuary from the AmasSeds (Amazon Shelf SEDiment Study) cruise of August 1989. Extensive removal of dissolved (0.22 [mu]m filtered) trivalent REEs from river water occurs in the low (0--6) salinity region. Removal by the salt-induced coagulation of river colloids leads to fractionation among the REE(III) series; the order of removal is light REEs > middle REEs > heavy REEs. There also is the enhanced removal of Ce (relative to trivalent La and Nd) in the low salinity (0--6) zone and in the zone of high biological activity. This is the first field observation of strong Ce removal associated with coagulation of river colloids and biological productivity. The argument is made that the decrease in the Ce anomaly across a biological front is caused by biologically mediated oxidation of Ce(III) to Ce(IV). Coagulation of river colloids and biologically mediated oxidation of Ce(III) lead to fractionation of REE(III) and redox modification of Ce. These processes result in the REE composition becoming fractionated relative to the Amazon River water and crust and more evolved toward the REE composition of the oceans. This study implies that reactions in estuaries play significant, yet poorly understood roles in controlling the REE composition and Ce anomaly of the oceans. 46 refs., 9 figs., 2 tabs.

  3. Rethinking early Earth phosphorus geochemistry

    PubMed Central

    Pasek, Matthew A.

    2008-01-01

    Phosphorus is a key biologic element, and a prebiotic pathway leading to its incorporation into biomolecules has been difficult to ascertain. Most potentially prebiotic phosphorylation reactions have relied on orthophosphate as the source of phosphorus. It is suggested here that the geochemistry of phosphorus on the early Earth was instead controlled by reduced oxidation state phosphorus compounds such as phosphite (HPO32?), which are more soluble and reactive than orthophosphates. This reduced oxidation state phosphorus originated from extraterrestrial material that fell during the heavy bombardment period or was produced during impacts, and persisted in the mildly reducing atmosphere. This alternate view of early Earth phosphorus geochemistry provides an unexplored route to the formation of pertinent prebiotic phosphorus compounds, suggests a facile reaction pathway to condensed phosphates, and is consistent with the biochemical usage of reduced oxidation state phosphorus compounds in life today. Possible studies are suggested that may detect reduced oxidation state phosphorus compounds in ancient Archean rocks. PMID:18195373

  4. Origin of fluorite mineralizations in the Nuba Mountains, Sudan and their rare earth element geochemistry

    NASA Astrophysics Data System (ADS)

    Ismail, Ibrahim; Baioumy, Hassan; Ouyang, Hegen; Mossa, Hesham; Aly, Hisham Fouad

    2015-12-01

    Among other mineralizations in the basement complex of the Nuba Mountains, fluorite occurs as lenses and veins in a number of localities. The rare earth elements (REE) geochemistry in these fluorites along with their petrography and fluid inclusion was investigated in this study to discuss the origin the fluorites and shed the light on the economic importance of the REE. Fluorites in the Nuba Mountains are classified into four categories based on their petrography. Category I (F1) is characterized by pink color and free of inclusions. Category II (F2) is zoned of alternating pink and colorless zones with euhedral outline or anhedral patchy pink and colorless fluorite enclosing category I fluorite and is usually sieved with submicroscopic silicate minerals. Category III (F3) is colorless, euhedral to anhedral fluorite and associated with quartz and/or orthoclase. Category IV (F4) is colorless, either massive or dispersed, corroded grains associated with calcite and pertain to the late introduced carbonatites in Dumbeir area. Gangue minerals in the studied fluorites include quartz, calcite, orthoclase and muscovite. The ?REE ranges between 541 and 10,430 ppm with an average of 3234 ppm. Chondrite-normalized REE patterns for fluorite from different localities exhibit LREE enrichment relative to HREE as shown by (La/Yb)N ratios that vary from 16 to 194 and significant positive Eu anomalies that are pronounced with Eu/Eu* from 1.1 to 2.5. The Tb/La and Tb/Ca ratios of fluorites in the present study indicate that they plot mainly in the pegmatitic or high-hydrothermal field with the characteristics of primary crystallization and remobilization trend. The clear heterogeneity of fluorite, abundance of growth zones, irregular shapes of grains, presence of fluorite inclusions in other minerals as well as the relatively high concentration of REE in the studied fluorites are supportive for this interpretation. The relatively high Tb/La (0.002-0.013) and low Tb/Ca (0.0000007-0.0000086) ratios of the studied fluorites suggest that they precipitated from fractionated ore-bearing fluids at a late stage of deposition. The microtherometric measurements of the primary inclusions show that the Nuba Mountains fluorites were formed at temperatures greater than 600 °C. These values along with the low salinity of the fluid inclusions indicates homogenize at moderate temperatures. Thus the studied fluorite probably formed during the late stages of pegmatite consolidation under magmatic-hydrothermal transition conditions supporting the previous conclusions from REE geochemistry.

  5. Rare-earth elements in the Permian Phosphoria Formation: Paleo proxies of ocean geochemistry

    USGS Publications Warehouse

    Piper, D.Z.; Perkins, R.B.; Rowe, H.D.

    2007-01-01

    The geochemistry of deposition of the Meade Peak Member of the Phosphoria Formation (MPM) in southeast Idaho, USA, a world-class sedimentary phosphate deposit of Permian age that extends over 300,000 km2, is ascertained from its rare earth element (REE) composition. Ratios of REE:Al2O3 suggest two sources-seawater and terrigenous debris. The seawater-derived marine fraction identifies bottom water in the Phosphoria Sea as O2-depleted, denitrifying (suboxic) most of the time, and seldom sulfate-reducing (anoxic). This interpretation is supported by earlier research that showed progressively greater ratios in the marine sediment fraction of Cr:Ni>V:Ni???Mo:Ni, relative to their ratios in seawater; for which marine Cr, V, and Mo can have a dominantly O2-depleted bottom-water source and Ni a photic-zone, largely algal, source. The water chemistry was maintained by a balance between bacterial oxidation of organic matter settling through the water column, determined largely by primary productivity in the photic zone, and the flux of oxidants into the bottom water via advection of seawater from the open ocean. Samples strongly enriched in carbonate fluorapatite, the dominant REE host mineral, have variable Er/Sm, Tm/Sm, and Yb/Sm ratios. Their distribution may represent greater advection of seawater between the Phosphoria Sea and open ocean during deposition of two ore zones than a center waste and greater upwelling of nutrient-enriched water into the photic zone. However, the mean rate of deposition of marine Ni, a trace nutrient of algae, and PO43-, a limiting nutrient, indicate that primary productivity was probably high throughout the depositional history. An alternative interpretation of the variable enrichments of Er, Tm, and Yb, relative to Sm, is that they may reflect temporally variable carbonate alkalinity of open-ocean seawater in Permian time. A more strongly negative Ce anomaly for all phosphatic units than the Ce anomaly of modern pelletal phosphate is further indicative of an elevated O2 concentration in the Permo-Carboniferous open ocean, as proposed by others, in contrast to the depletion of O2 in the bottom water of the Phosphoria Sea itself. The oceanographic conditions under which the deposit accumulated were likely similar to conditions under which many sedimentary phosphate deposits have accumulated and to conditions under which many black shales that are commonly phosphate poor have accumulated. A shortcoming of several earlier studies of these deposits has resulted from a failure to examine the marine fraction of elements separate from the terrigenous fraction. ?? 2007 Elsevier Ltd. All rights reserved.

  6. Rare Earth Element Geochemistry of the Shergottites LAR 12095, 12240, and 12011

    NASA Astrophysics Data System (ADS)

    Dunham, E.; Wadhwa, M.; Tucker, K.; Balta, J. B.; McSween, H. Y.

    2015-07-01

    REE geochemistry confirms pairing of shergottites LAR 12095 and LAR 12240, and of LAR 12011 with LAR 06319. Calculations of magmatic fO2 suggest that these shergottites originated from martian mantle sources with different redox conditions.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Zheng, Liugen; Liu, Guijian; Chou, Chen-Lin; Qi, Cuicui; Zhang, Ying

    2007-10-01

    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.

  9. 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.

  10. 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. PMID:26247412

  11. 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.

  12. 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.

  13. Rare earth element geochemistry of massive sulfides-sulfates and gossans on the Southern Explorer Ridge

    SciTech Connect

    Barrett, T.J. ); Jarvis, I. ); Jarvis, K.E. )

    1990-07-01

    Massive sulfide-sulfate deposits on the Southern Explorer Ridge were analyzed for 14 rare earth elements (REE) by a modified inductively coupled plasma-mass spectrometric technique that included a correction for high Ba content. Bulk samples of finely intermixed sulfides, sulfate, and amorphous silica contain {Sigma}REE concentrations of {le} 6 ppm. REE patterns range from (1) strongly enriched in light REE with positive Eu anomalies, to (2) relatively flat with positive Eu anomalies and slightly negative Ce anomalies, to (3) slightly enriched in light REE with moderately negative Ce anomalies. Pattern 1 is similar to that of 300-350 C solutions discharging at vents on the East Pacific Rise and the Mid-Atlantic Ridge, whereas pattern 3 resembles REE distributions in normal oceanic bottom waters. The sulfide-sulfate patterns are interpreted to result from variable mixtures of hydrothermal and normal seawater. Barite in gossans capping the mounds has an REE pattern almost identical to patterns of high-temperature vent solutions. Hydrothermal barite has lower REE contents and a different REE pattern relative to hydrogenous barite formed slowly on the sea floor.

  14. The Use of Lead Isotope and Rare Earth Element Geochemistry for Forensic Geographic Provenancing

    NASA Astrophysics Data System (ADS)

    Carey, A.; Darrah, T.; Harrold, Z.; Prutsman-Pfeiffer, J.; Poreda, R.

    2008-12-01

    Lead isotope and rare earth element composition of modern human bones are analyzed to explore their utility for geographical provenancing. DNA analysis is the standard for identification of individuals. DNA analysis requires a DNA match for comparison. Thus, DNA analysis is of limited use in cases involving unknown remains. Trace elements are incorporated into bones and teeth during biomineralization, recording the characteristics of an individual's geochemical environment. Teeth form during adolescence, recording the geochemical environment of an individual's youth. Bones remodel throughout an individual's lifetime. Bones consist of two types of bone tissue (cortical and trabecular) that remodel at different rates, recording the geochemical environment at the time of biomineralization. Cortical bone tissue, forming the outer surface of bones, is dense, hard tissue that remodels in 25-30 yrs. Conversely, trabecular bone tissue, the inner cavity of bones, is low density, porous and remodels in 2-5 years. Thus, analyzing teeth and both bone tissues allows for the development of a geographical time line capable of tracking immigration patterns through time instead of only an individual's youth. Geochemical isotopic techniques (Sr, O, C, N) have been used for geographical provenancing in physical anthropology. The isotopic values of Sr, C, O, N are predominantly a function of soil compositions in areas where food is grown or water is consumed. Application of these provenancing techniques has become difficult as an individual's diet may reflect the isotopic composition of foods obtained at the local grocer as opposed to local soil compositions. Thus, we explore the use of REEs and Pb isotopes for geographical provenancing. Pb and REEs are likely more reliable indicators of modern geographical location as their composition are high in bio-available sources such as local soils, atmospheric aerosols, and dust as opposed to Sr, C, O, N that are controlled by food and drinking water. Lead isotope and REE analysis of trabecular and cortical bone tissue of 60 femoral heads resected during hip replacement surgery at the Univ. of Roch. Medical Center were analyzed by a combination of TIMS and ICP-MS. Results show that Pb compositions are consistent with local soil with variable inputs from known environmental sources. Several samples demonstrate inputs from known environmental sources (e.g. Mississippi Valley ore) that was used in paint, solder, and US gasoline. Additionally, results suggest bioincorporation of Pb with isotopic composition consistent with that observed for Canadian gasoline aerosols. Immigrants included in the study show Pb compositions distinctly different than local residents.

  15. Rare earth element mineralogy, geochemistry, and preliminary resource assessment of the Khanneshin carbonatite complex, Helmand Province, Afghanistan

    USGS Publications Warehouse

    Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Buttleman, Kim P.

    2011-01-01

    There is increased concern about the future availability of rare earth elements (REE) because of China's dominance as the supplier of more than 95 percent of world REE output, their decision to restrict exports of rare earth products, and the rapid increase in world-wide consumption of rare earth product. As a result, countries such as the United States, Japan, and member nations of the European Union face a future of tight supplies and high prices for rare earth products unless other sources of REE are found and developed (Long and others, 2010; U.S. Geological Survey, 2011, p. 128-129, 184-185). We report and describe a significant new deposit of light rare earth elements (LREE), estimated at 1 Mt, within the Khanneshin carbonatite complex of south Afghanistan. The potential resource is located in a remote and rugged part of the igneous complex in a region previously identified by Soviet geologists in the 1970s. This report reviews the geologic setting of LREE deposit, presents new geochemical data documenting the grade of LREE mineralization, briefly describes the mineralogy and mineralogical associations of the deposit, and presents a preliminary estimate of LREE resources based on our current understanding of the geology.

  16. Rare earth and major element geochemistry of Eocene fine-grained sediments in oil shale- and coal-bearing layers of the Meihe Basin, Northeast China

    NASA Astrophysics Data System (ADS)

    Bai, Yueyue; Liu, Zhaojun; Sun, Pingchang; Liu, Rong; Hu, Xiaofeng; Zhao, Hanqing; Xu, Yinbo

    2015-01-01

    The Meihe Basin is a Paleogene pull-apart basin. Long-flame coal, lignite and oil shale are coexisting energy resources deposited in this basin. Ninety-seven samples, including oil shales, coals, brown to gray silt and mudstone, have been collected from the oil shale- and coal-bearing layers to discover the rare earth element geochemistry. The total REE contents of oil shales and coals are 137-256 ?g/g and 64-152 ?g/g respectively. The chondrite-normalized patterns of oil shales and coals show LREE enrichments, HREE deficits, negative Eu anomalies and negligible Ce anomalies. The chemical index of alteration (CIA) as well as some trace elements is often used to reflect the paleoenvironment at the time of deposition. The results show that fine-grained sediments in both layers were deposited in dysoxic to oxic conditions and in a warm and humid climate, and coals were deposited in a warmer and more humid climate than oil shales. Oil shales and coals are both in the early stage of diagenesis and of terrigenous origin. Besides, diagrams of some major, trace and rare earth elements show that the fine-grained sediments of both layers in the Meihe Basin are mainly from the felsic volcanic rocks and granite, and that their source rocks are mostly deposited in the continental inland arc setting. The analysis of major elements shows that Si, Al, K and Ti, in both layers, are found mainly in a mixed clay mineral assemblage and that Si is also found in quartz. Sodium occurs primarily in clay minerals, whereas Ca is found mainly in the organic matter. In the coal-bearing layer, iron is mainly controlled by organic matter rather than detrital minerals. In contrast, in the oil shale-bearing layer, neither detrital minerals nor organic matter exert a control on the iron content. Analyzing the relationship between rare earth elements and major elements shows that REEs in the oil shales and the coals are both of terrigenous origin and are mainly controlled by detrital minerals rather than by organic matter. In both layers, REEs have no relationship with fine-grained phosphates, and during the weathering process, the REEs were not very mobile and were resistant to fractionation.

  17. Rare-earth element geochemistry and the origin of andesites and basalts of the Taupo Volcanic Zone, New Zealand

    USGS Publications Warehouse

    Cole, J.W.; Cashman, K.V.; Rankin, P.C.

    1983-01-01

    Two types of basalt (a high-Al basalt associated with the rhyolitic centres north of Taupo and a "low-Al" basalt erupted from Red Crater, Tongariro Volcanic Centre) and five types of andesite (labradorite andesite, labradorite-pyroxene andesite, hornblende andesite, pyroxene low-Si andesite and olivine andesite/low-Si andesite) occur in the Taupo Volcanic Zone (TVZ), North Island, New Zealand. Rare-earth abundances for both basalts and andesites are particularly enriched in light rare-earth elements. High-Al basalts are more enriched than the "low-Al" basalt and have values comparable to the andesites. Labradorite and labradorite-pyroxene andesites all have negative Eu anomalies and hornblende andesites all have negative Ce anomalies. The former is probably due to changing plagioclase composition during fractionation and the latter to late-stage hydration of the magma. Least-squares mixing models indicate that neither high-Al nor "low-Al" basalts are likely sources for labradorite/labradorite-pyroxene andesites. High-Al basalts are considered to result from fractionation of olivine and clinopyroxene from a garnet-free peridotite at the top of the mantle wedge. Labradorite/labradorite-pyroxene andesites are mainly associated with an older NW-trending arc. The source is likely to be garnet-free but it is not certain whether the andesites result from partial melting of the top of the subducting plate or a hydrated lower portion of the mantle wedge. Pyroxene low-Si andesites probably result from cumulation of pyroxene and calcic plagioclase within labradorite-pyroxene andesites, and hornblende andesites by late-stage hydration of labradorite-pyroxene andesite magma. Olivine andesites, low-Si andesites and "low-Al" basalts are related to the NNE-trending Taupo-Hikurangi arc structure. Although the initial source material is different for these lavas they have probably undergone a similar history to the labradorite/labradorite-pyroxene andesites. All lavas show evidence of crustal contamination. ?? 1983.

  18. Early depositional history of metalliferous sediments in the Atlantis II Deep of the Red Sea: Evidence from rare earth element geochemistry

    NASA Astrophysics Data System (ADS)

    Laurila, Tea E.; Hannington, Mark D.; Petersen, Sven; Garbe-Schönberg, Dieter

    2014-02-01

    The Atlantis II Deep is a brine-filled depression on the slowly spreading Red Sea rift axis. It is by far the largest deposit of hydrothermally precipitated metals on the present ocean floor and the only known modern deposit that is analogous to laminated Fe-rich chemical sediments, such as banded iron formation (BIF). The brine pool at the bottom of the Atlantis II Deep creates an environment where most of the hydrothermally sourced elements can be dispersed and deposited over an area of ˜60 km2. We analyzed the rare earth element concentrations in 100 small-volume samples from 9 cores in different parts of the Atlantis II Deep to better understand the origins of different types of metalliferous sediments (detrital, proximal hydrothermal and distal hydrothermal). Our results agree with earlier studies based on larger bulk samples that show the composition of the major depositional units is related to major changes in the location and intensity of hydrothermal activity and the amount of hydrothermal versus background sedimentation. In this paper, we address the origins of chemically distinct laminae (down to sub-millimeter) that correspond to ˜annual deposition. REE patterns clearly reflect 3 different sources (e.g., detrital, scavenging, direct hydrothermal input). Detrital REE that are delivered to the Deep from outside account for most of the REE in the sediments of the Atlantis II Deep, similar to BIF, and are unaffected by fractionation due to hydrothermal processes during deposition and diagenesis. Fe- and Mn-(oxy)hydroxides that form at the anoxic-oxic boundary scavenge REE from the brine pool as they settle. The Fe-(oxy)hydroxides contain a larger proportion of REE from seawater than any other sediment-type and also scavenge REE from pore waters after deposition. In contrast, the Mn-(oxy)hydroxides dissolve before deposition and thus function as transporting agents between seawater and the brine. However, there is little evidence for direct seawater influence in the REE geochemistry of the sediments (e.g., Y/Ho ratio). Non-ferrous sulfides form proximal to the hydrothermal vent source and inherit an hydrothermal REE pattern. The total REE content of the presently forming Fe-(oxy)hydroxides is very low due to limited input of REE into the brine. The largest proportion of non-detrital REE appears to have been deposited early in the history of the basin from an initial brine pool that was relatively enriched in REE, followed by a change in REE chemistry in later sediments. Similar abrupt changes in the REE chemistry of ancient chemical sediments may record similar processes, including changes in local basin evolution and input of REE from different sources.

  19. The Medical Geochemistry of Dusts, Soils, and Other Earth Materials

    NASA Astrophysics Data System (ADS)

    Plumlee, G. S.; Ziegler, T. L.

    2003-12-01

    "Town clenched in suffocating grip of asbestos"USA Today, article on Libby,Montana, February, 2000"Researchers find volcanoes are bad for your health… long after they finish erupting"University of WarwickPress Release, 1999"Toxic soils plague city - arsenic, lead in 5 neighborhoods could imperil 17,000 residents"Denver Post, 2002"Ill winds - dust storms ferry toxic agents between countries and even continents"Science News, 2002A quick scan of newspapers, television, science magazines, or the internet on any given day has a fairly high likelihood of encountering a story (usually accompanied by a creative headline such as those above) regarding human health concerns linked to dusts, soils, or other earth materials. Many such concerns have been recognized and studied for decades, but new concerns arise regularly.Earth scientists have played significant roles in helping the medical community understand some important links between earth materials and human health, such as the role of asbestos mineralogy in disease (Skinner et al., 1988; Ross, 1999; Holland and Smith, 2001), and the role of dusts generated by the 1994 Northridge, California, earthquake in an outbreak of Valley Fever ( Jibson et al., 1998; Schneider et al., 1997).Earth science activities tied to health issues are growing (Skinner and Berger, 2003), and are commonly classified under the emerging discipline of medical geology (Finkelman et al., 2001; Selinus and Frank, 2000; Selinus, in press).Medical geochemistry (also referred to as environmental geochemistry and health: Smith and Huyck (1999), Appleton et al. (1996)) can be considered as a diverse subdiscipline of medical geology that deals with human and animal health in the context of the Earth's geochemical cycle ( Figure 1). Many medical geochemistry studies have focused on how chemical elements in rocks, soils, and sediments are transmitted via water or vegetation into the food chain, and how regional geochemical variations can result in disease clusters either through dietary deficiency of essential elements or dietary excess of toxic elements. (28K)Figure 1. Potential human exposure routes within the earth's geochemical cycle can come from a wide variety of both natural and anthropogenic sources. This chapter focuses on a somewhat narrower area of medical geochemistry: the study of mechanisms of uptake of earth materials by humans and animals and their reactions to these materials. In order for earth materials to affect health, they must first interact with the body across key interfaces such as the respiratory tract, gastrointestinal tract, skin, and eyes. In some way, all of these interfaces require the earth materials to interact chemically with water-based body fluids such as lung fluids, gastrointestinal fluids, saliva, or blood plasma.The primary goal of this chapter, co-authored by a geochemist and a toxicologist, is to provide both geochemists and scientists from health disciplines with an overview of the potential geochemical mechanisms by which earth materials can influence human health. It is clear that significant opportunities for advancement in this arena will require continued and increased research collaborations between geochemists and their counterparts in the health disciplines.

  20. Geochemistry.

    ERIC Educational Resources Information Center

    Fyfe, William S.

    1979-01-01

    Techniques in geochemistry continue to improve in sensitivity and scope. The exciting areas of geochemistry still include the classical fields of the origin of the elements and objects in space, but environmental crisis problems are important as well. (Author/BB)

  1. 12.479 Trace-Element Geochemistry, Fall 2006

    E-print Network

    Frey, Frederick August

    Focuses on element distribution in rocks and minerals using data obtained from natural and experimental systems. Emphasizes models describing trace-element partitioning and applications of trace-element geochemistry to ...

  2. 12.479 Trace-Element Geochemistry, Spring 2009

    E-print Network

    Frey, Frederick

    The emphasis of this course is to use Trace Element Geochemistry to understand the origin and evolution of igneous rocks. The approach is to discuss the parameters that control partitioning of trace elements between phases ...

  3. Insights into Igneous Geochemistry from Trace Element Partitioning

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Hanson, B. Z.

    2001-01-01

    Partitioning of trivalent elements into olivine are used to explore basic issues relevant to igneous geochemistry, such as Henry's law. Additional information is contained in the original extended abstract.

  4. Rare earth element geochemistry of acid-sulphate and acid-sulphate-chloride geothermal systems from Yellowstone National Park, Wyoming, USA

    SciTech Connect

    Lewis, A.J.; Palmer, M.R.; Kemp, A.J.; Sturchio, N.C.

    1997-02-01

    Rare earth element (REE) concentrations have been determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in acid-sulphate and acid-sulphate-chloride waters and the associated sinters and volcanic rocks from the Yellowstone National Park (YNP), Wyoming, USA, geothermal system. REE concentrations in the volcanic rocks range from 222 to 347 ppm: their chondrite-normalised REE patterns are typical of upper continental crust, with LREE > HREE and negative Eu anomalies. Total REE concentrations in the fluids range from 3 to 1133 nmol kg{sup -1} ({ge}162 ppm), and {Sigma}REE concentrations in sinter are {ge}181 ppm. REE abundances and patterns in drill core material from YNP indicate some REE mobility. Relative to the host rocks the REE patterns of the fluids are variably depleted in HREEs and LREEs, and usually have a pronounced positive Eu anomaly. This decoupling of Eu from the REE suite suggests that (1) Eu has been preferentially removed either from the host rock glass or from the host rock minerals, or (2) the waters are from a high temperature or reducing environment where Eu{sup 2+} is more soluble than the trivalent REEs. Since the latter is inconsistent with production of acid-sulphate springs in a low temperature, oxidising near-surface environment, we suggest that the positive Eu anomalies in the fluids result from preferential dissolution of a Eu-rich phase in the host rock. Spatial and temporal variations in major element chemistry and pH of the springs sampled from Norris Geyser Basin and Crater Hills accompany variations in REE concentrations and patterns of individual geothermal springs. These are possibly related to changes in subsurface plumbing, which results in variations in mixing and dilution of the geothermal fluids and may have lead to changes in the extent and nature of REE complexing. 37 refs., 7 figs., 4 tabs.

  5. The rare earth element geochemistry of acid-sulphate and acid-sulphate-chloride geothermal systems from Yellowstone National Park, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Lewis, Anita J.; Palmer, Martin R.; Sturchio, Neil C.; Kemp, Anthony J.

    1997-02-01

    Rare earth element (REE) concentrations have been determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in acid-sulphate and acid-sulphate-chloride waters and the associated sinters and volcanic rocks from the Yellowstone National Park (YNP), Wyoming, USA, geothermal system. REE concentrations in the volcanic rocks range from 222 to 347 ppm; their chondite-normalised REE patterns are typical of upper continental crust, with LREE > HREE and negative Eu anomalies. Total REE concentrations in the fluids range from 3 to 1133 nmol kg -1 (? 162 ppm), and ?REE concentrations in sinter are ? 181 ppm. REE abundances and patterns in drill core material from YNP indicate some REE mobility. Normalisation of REE concentrations in altered Lava Creek Tuff (LCT) from Y-12 drill core to REE concentrations in fresh LCT indicate that the REE overall have been depleted with the exception of Eu, which has been decoupled from the REE series and concentrated in the altered rocks. Relative to the host rocks the REE patterns of the fluids are variably depleted in HREEs and LREEs, and usually have a pronounced positive Eu anomaly. This decoupling of Eu from the REE suite suggests that (1) Eu has been preferentially removed either from the host rock glass or from the host rock minerals, or (2) the waters are from a high temperature or reducing environment where Eu 2+ is more soluble than the trivalent REEs. Since the latter is inconsistent with production of acid-sulphate springs in a low temperature, oxidising near-surface environment, we suggest that the positive Eu anomalies in the fluids result from preferential dissolution of a Eu-rich phase in the host rock. Spatial and temporal variations in major element chemistry and pH of the springs sampled from Norris Geyser Basin and Crater Hills accompany variations in REE concentrations and patterns of individual geothermal springs. These are possibly related to changes in subsurface plumbing, which results in variations in mixing and dilution of the geothermal fluids and may have lead to changes in the extent and nature of REE complexing.

  6. Fluid inclusion, rare earth element geochemistry, and isotopic characteristics of the eastern ore zone of the Baiyangping polymetallic Ore district, northwestern Yunnan Province, China

    NASA Astrophysics Data System (ADS)

    Feng, Caixia; Bi, Xianwu; Liu, Shen; Hu, Ruizhong

    2014-05-01

    The Baiyangping Cu-Ag polymetallic ore district is located in the northern part of the Lanping-Simao foreland fold belt, which lies between the Jinshajiang-Ailaoshan and Lancangjiang faults in western Yunnan Province, China. The source of ore-forming fluids and materials within the eastern ore zone were investigated using fluid inclusion, rare earth element (REE), and isotopic (C, O, and S) analyses undertaken on sulfides, gangue minerals, wall rocks, and ores formed during the hydrothermal stage of mineralization. These analyses indicate: (1) The presence of five types of fluid inclusion, which contain various combinations of liquid (l) and vapor (v) phases at room temperature: (a) H2O (l), (b) H2O (l) + H2O (v), (c) H2O (v), (d) CmHn (v), and (e) H2O (l) + CO2 (l), sometimes with CO2 (v). These inclusions have salinities of 1.4-19.9 wt.% NaCl equivalents, with two modes at approximately 5-10 and 16-21 wt.% NaCl equivalent, and homogenization temperatures between 101 °C and 295 °C. Five components were identified in fluid inclusions using Raman microspectrometry: H2O, dolomite, calcite, CH4, and N2. (2) Calcite, dolomitized limestone, and dolomite contain total REE concentrations of 3.10-38.93 ppm, whereas wall rocks and ores contain REE concentrations of 1.21-196 ppm. Dolomitized limestone, dolomite, wall rock, and ore samples have similar chondrite-normalized REE patterns, with ores in the Huachangshan, Xiaquwu, and Dongzhiyan ore blocks having large negative ?Ce and ?Eu anomalies, which may be indicative of a change in redox conditions during fluid ascent, migration, and/or cooling. (3) ?34S values for sphalerite, galena, pyrite, and tetrahedrite sulfide samples range from -7.3‰ to 2.1‰, a wide range that indicates multiple sulfur sources. The basin contains numerous sources of S, and deriving S from a mixture of these sources could have yielded these near-zero values, either by mixing of S from different sources, or by changes in the geological conditions of seawater sulfate reduction to sulfur. (4) The C-O isotopic analyses yield ?13C values from ca. zero to -10‰, and a wider range of ?18O values from ca. +6 to +24‰, suggestive of mixing between mantle-derived magma and marine carbonate sources during the evolution of ore-forming fluids, although potential contributions from organic carbon and basinal brine sources should also be considered. These data indicate that ore-forming fluids were derived from a mixture of organism, basinal brine, and mantle-derived magma sources, and as such, the eastern ore zone of the Baiyangping polymetallic ore deposit should be classified as a “Lanping-type” ore deposit.

  7. Trace element geochemistry of CR chondrite metal

    NASA Astrophysics Data System (ADS)

    Jacquet, Emmanuel; Paulhiac-Pison, Marine; Alard, Olivier; Kearsley, Anton T.; Gounelle, Matthieu

    2013-10-01

    We report trace element analyses by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of metal grains from nine different CR chondrites, distinguishing grains from chondrule interior ("interior grains"), chondrule surficial shells ("margin grains"), and the matrix ("isolated grains"). Save for a few anomalous grains, Ni-normalized trace element patterns are similar for all three petrographic settings, with largely unfractionated refractory siderophile elements and depleted volatile Au, Cu, Ag, S. All three types of grains are interpreted to derive from a common precursor approximated by the least-melted, fine-grained objects in CR chondrites. This also excludes recondensation of metal vapor as the origin of the bulk of margin grains. The metal precursors were presumably formed by incomplete condensation, with evidence for high-temperature isolation of refractory platinum-group-element (PGE)-rich condensates before mixing with lower temperature PGE-depleted condensates. The rounded shape of the Ni-rich, interior grains shows that they were molten and that they equilibrated with silicates upon slow cooling (1-100 K h-1), largely by oxidation/evaporation of Fe, hence their high Pd content, for example. We propose that Ni-poorer, amoeboid margin grains, often included in the pyroxene-rich periphery common to type I chondrules, result from less intense processing of a rim accreted onto the chondrule subsequent to the melting event recorded by the interior grains. This means either that there were two separate heating events, which formed olivine/interior grains and pyroxene/margin grains, respectively, between which dust was accreted around the chondrule, or that there was a single high-temperature event, of which the chondrule margin records a late "quenching phase," in which case dust accreted onto chondrules while they were molten. In the latter case, high dust concentrations in the chondrule-forming region (at least three orders of magnitude above minimum mass solar nebula models) are indicated.

  8. DALHOUSIE UNIVERSITY, DEPARTMENT OF EARTH SCIENCES Assistant Professor -Geophysics, Sedimentology, or Geochemistry

    E-print Network

    Brownstone, Rob

    DALHOUSIE UNIVERSITY, DEPARTMENT OF EARTH SCIENCES Assistant Professor - Geophysics, Sedimentology, or Geochemistry The Department of Earth Sciences at Dalhousie University invites applications for a faculty research projects. Essential qualifications include a Ph.D. in Earth Sciences or closely related field

  9. Geochemistry

    ERIC Educational Resources Information Center

    Ailin-Pyzik, Iris B.; Sommer, Sheldon E.

    1977-01-01

    Enumerates some of the research findings in geochemistry during the last year, including X-ray analysis of the Mars surface, trace analysis of fresh and esterarine waters, and analysis of marine sedements. (MLH)

  10. Tracking Iceland Plume Motion Using Trace Element Geochemistry

    NASA Astrophysics Data System (ADS)

    Fitton, J. G.; Walters, R. L.; Jones, S. M.

    2011-12-01

    The Greenland-Scotland Ridge (GSR) is a hotspot track built by interaction between the Mid Atlantic Ridge (MAR) and the Iceland mantle plume. Unlike most other hotspot tracks built by ridge-plume interaction, the GSR is 2 to 3 times wider than the plume conduit in the upper mantle. (This unusual wide morphology arises because Icelandic crust changes significantly in thickness within a few million years of accretion, probably mainly by viscous flow in the hot lower crust). The upshot is that the GSR cannot be compared directly with theoretical plume tracks from hotspot reference frame models. However, it is possible to track the position of the Iceland plume conduit using the trace element geochemistry of basaltic lavas. Away from the plume conduit, plate spreading drives upwelling of mantle through the melting region. Above the plume conduit, plume-driven flow forces mantle through the lower part of the melting region faster than the plate-driven upwelling rate. The average depth of melting is therefore greater directly above the plume conduit than away from the plume conduit, and this difference in average melting depth means that melts generated directly above the plume conduit are relatively enriched in incompatible trace elements. Joint modelling of trace element compositions and crustal thickness can also be used to establish location of melting relative to the plume conduit. To date, these concepts have been used only to explain compositional variations in modern (post-glacial) Icelandic lavas; in this study we show that the same concepts can be applied to map the location of the plume conduit throughout the onshore Icelandic geological record (since the middle Miocene, c. 16 Ma). The plume track thus determined is in reasonable agreement with theoretical tracks calculated under the assumption that the Iceland Plume has remained fixed relative to other Indo-Atlantic hotspots. This result also supports the idea that episodic relocations of the onshore part of the MAR act to maintain the spreading axis above the plume conduit.

  11. Rare earth elements: end use and recyclability

    USGS Publications Warehouse

    Goonan, Thomas G.

    2011-01-01

    Rare earth elements are used in mature markets (such as catalysts, glassmaking, lighting, and metallurgy), which account for 59 percent of the total worldwide consumption of rare earth elements, and in newer, high-growth markets (such as battery alloys, ceramics, and permanent magnets), which account for 41 percent of the total worldwide consumption of rare earth elements. In mature market segments, lanthanum and cerium constitute about 80 percent of rare earth elements used, and in new market segments, dysprosium, neodymium, and praseodymium account for about 85 percent of rare earth elements used. Regardless of the end use, rare earth elements are not recycled in large quantities, but could be if recycling became mandated or very high prices of rare earth elements made recycling feasible.

  12. Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

    NASA Technical Reports Server (NTRS)

    Righter, K.; Pando, K.; Danielson, L.; Nickodem, K.

    2014-01-01

    Depletions of siderophile elements in mantles have placed constraints on the conditions on core segregation and differentiation in bodies such as Earth, Earth's Moon, Mars, and asteroid 4 Vesta. Among the siderophile elements there are a sub-set that are also volatile (volatile siderophile elements or VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd), and thus can help to constrain the origin of volatile elements in these bodies, and in particular the Earth and Moon. One of the fundamental observations of the geochemistry of the Moon is the overall depletion of volatile elements relative to the Earth, but a satisfactory explanation has remained elusive. Hypotheses for Earth include addition during accretion and core formation and mobilized into the metallic core, multiple stage origin, or addition after the core formed. Any explanation for volatile elements in the Earth's mantle must also be linked to an explanation of these elements in the lunar mantle. New metal-silicate partitioning data will be applied to the origin of volatile elements in both the Earth and Moon, and will evaluate theories for exogenous versus endogenous origin of volatile elements.

  13. Volatile Element Geochemistry in the Lower Atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Schaefer, L.; Fegley, B., Jr.

    2004-01-01

    We computed equilibrium abundances of volatile element compounds as a function of altitude in Venus lower atmosphere. The elements included are generally found in volcanic gases and sublimates on Earth and may be emitted in volcanic gases on Venus or volatilized from its hot surface. We predict: 1) PbS, Bi2S3, or possibly a Pb-Bi sulfosalt are the radar bright heavy metal frost in the Venusian highlands; 2) It should be possible to determine Venus' age by Pb-Pb dating of PbS condensed in the Venusian highlands, which should be a representative sample of Venusian lead; 3) The gases HBr, PbCl2, PbBr2, As4O6, As4S4, Sb4O6, BiSe, InBr, InCl, Hg, TlCl, TlBr, SeS, Se2-7, HI, I, I2, ZnCl2, and S2O have abundances greater than 0.1 ppbv in our nominal model and may be spectroscopically observable; 4) Cu, Ag, Au, Zn, Cd, Ge, and Sn are approx. 100 % condensed at the 740 K (0 km) level on Venus.

  14. Mineral resource of the month: rare earth elements

    USGS Publications Warehouse

    U.S. Geological Survey

    2011-01-01

    The article provides information on rare earth elements, which are group of 17 natural metallic elements. The rare earth elements are scandium, yttrium and lanthanides and classified into light rare earth elements (LREE) and heavy rate earth elements (HREE). The principal ores of the rare earth elements are identified. An overview of China's production of 97 percent of the rare earths in the world is provided. Commercial applications of rare earths are described.

  15. Rare Earth Element Mines, Deposits, and Occurrences

    USGS Publications Warehouse

    Orris, Greta J.; Grauch, Richard I.

    2002-01-01

    Data on rare earth (including yttrium) mines, deposits, and occurrences were compiled as part of an effort by the USGS and the University of Arizona Center for Mineral Resources to summarize current knowledge on the supply and demand outlook and related topics for this group of elements. Economic competition and environmental concerns are increasingly constraining the mining and processing of rare earths from the Mountain Pass mine in California. For many years, the deposit at Mountain Pass was the world's dominant source of rare earth elements and the United States was essentially self-sufficient. Starting approximately 10 years ago, the U.S. has become increasingly dependent (> 90 percent of separated rare earths) upon imports from China, now the dominant source of rare earths. A knowledge of the known economic and noneconomic sources of rare earths is basic to evaluating the outlook for rare earth supply and associated issues.

  16. Moving KML geometry elements within Google Earth

    NASA Astrophysics Data System (ADS)

    Zhu, Liang-feng; Wang, Xi-feng; Pan, Xin

    2014-11-01

    During the process of modeling and visualizing geospatial information on the Google Earth virtual globe, there is an increasing demand to carry out such operations as moving geospatial objects defined by KML geometry elements horizontally or vertically. Due to the absence of the functionality and user interface for performing the moving transformation, it is either hard or impossible to interactively move multiple geospatial objects only using the existing Google Earth desktop application, especially when the data sets are in large volume. In this paper, we present a general framework and associated implementation methods for moving multiple KML geometry elements within Google Earth. In our proposed framework, we first load KML objects into the Google Earth plug-in, and then extract KML geometry elements from the imported KML objects. Subsequently, we interactively control the movement distance along a specified orientation by employing a custom user interface, calculate the transformed geographic location for each KML geometry element, and adjust geographic coordinates of the points in each KML objects. And finally, transformed KML geometry elements can be displayed in Google Earth for 3D visualization and spatial analysis. A key advantage of the proposed framework is that it provides a simple, uniform and efficient user interface for moving multiple KML geometry elements within Google Earth. More importantly, the proposed framework and associated implementations can be conveniently integrated into other customizable Google Earth applications to support interactively visualizing and analyzing geospatial objects defined by KML geometry elements.

  17. Geochemistry: does U-Pb date Earth's core formation?

    PubMed

    Yin, Qing-zhu; Jacobsen, Stein B

    2006-11-01

    Constraining the timing of the formation of Earth's core, which defines the birth of our planet, is essential for understanding the early evolution of Earth-like planets. Wood and Halliday and Halliday discuss the apparent discrepancy between the U-Pb (60-80 Myr) and Hf-W clocks (30 Myr) in determining the timescale of Earth's accretion and core formation. We find that the information the authors present is at times contradictory (for example, compare Fig. 1 in ref. 1 with Fig. 1 in ref. 2) and confusing and could suggest that the U-Pb clock constrains core formation better than the Hf-W system. Here we point out the limitations of the U-Pb system and show that the U-Pb age cannot be used to argue for protracted accretion and/or core formation (>50 Myr) because this clock only records the processes that occurred during the last 1% of Earth's accretion and core formation in the Wood and Halliday mechanism. PMID:17080033

  18. Sedimentology, Geochemistry, and Geophysics of the Cambrian Earth System

    NASA Astrophysics Data System (ADS)

    Creveling, Jessica Renee

    Within this dissertation, I document how—and hypothesize why—the quirks and qualities of the Cambrian Period demarcate this interval as fundamentally different from the preceding Proterozoic Eon and succeeding periods of the Phanerozoic Eon. To begin, I focus on the anomalous marine deposition of the mineral apatite. Sedimentary sequestration of phosphorus modulates the capacity for marine primary productivity and, thus, the redox state of the Earth system. Moreover, sedimentary apatite minerals may entomb and replicate skeletal and soft-tissue organisms, creating key aspects of the fossil record from which paleontologists deduce the trajectory of animal evolution. I ask what geochemical redox regime promoted the delivery of phosphorus to Cambrian seafloors and conclude that, for the case of the Thorntonia Limestone, apatite nucleation occurred under anoxic, ferruginous subsurface water masses. Moreover, I infer that phosphorus bound to iron minerals precipitated from the water column and organic-bound phosphorus were both important sources of phosphorus to the seafloor. Petrographic observations allow me to reconstruct the early diagenetic pathways that decoupled phosphorus from these delivery shuttles and promoted the precipitation of apatite within the skeletons of small animals. Together, mechanistic understandings of phosphorus delivery to, and retention within, seafloor sediment allow us to constrain hypotheses for the fleeting occurrence of widespread apatite deposition and exquisite fossil preservation within Cambrian sedimentary successions. Next, I describe and quantify the nature of carbonate production on a marine platform deposited at the hypothesized peak of Cambrian skeletal carbonate production. I find that fossils represent conspicuous, but volumetrically subordinate components of early Cambrian carbonate reef ecosystems and that despite the evolution of mineralized skeletons, Cambrian carbonate platforms appear similar to their Neoproterozoic counterparts, primarily reflecting abiotic and microbial deposition. Finally, I investigate the geodynamic mechanism responsible for rapid, oscillatory true polar wander (TPW) events proposed for the Neoproterozoic and Phanerozoic Earth on the basis of paleomagnetic data. Using geodynamic models, I demonstrate that elastic strength in the lithosphere and stable excess ellipticity of Earth's figure provided sufficient stabilization to return the pole to its original state subsequent to convectively-driven TPW.

  19. Trace Element Geochemistry of Tissint, the Newest Shergottite Fall

    NASA Astrophysics Data System (ADS)

    Sanborn, M. E.; Wadhwa, M.; Balta, J. B.; McSween, H. Y.

    2012-09-01

    We report trace element abundances in individual mineral phases, as well as in the bulk rock, of Tissint with the goal of understanding its petrogenetic history in relation to the other known olivine-phyric shergottites.

  20. Trace Element Geochemistry of Martian Iddingsite in the Lafayette Meteorite

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Lindstrom, David J.

    1997-01-01

    The Lafayette meteorite contains abundant iddingsite, a fine-grained intergrowth of smectite clay, ferrihydrite, and ionic salt minerals. Both the meteorite and iddingsite formed on Mars. Samples of iddingsite, olivine, and augite pyroxene were extracted from Lafayette and analyzed for trace elements by instrumental neutron activation. Our results are comparable to independent analyses by electron and ion microbeam methods. Abundances of most elements in the iddingsite do not covary significantly. The iddingsite is extremely rich in Hg, which is probably terrestrial contamination. For the elements Si, Al, Fe, Mn, Ni, Co, and Zn, the composition of the iddingsite is close to a mixture of approximately 50% Lafayette olivine + approximately 40% Lafayette siliceous glass + approximately 1O% water. Concordant behavior among these elements is not compatible with element fractionations between smectite and water, but the hydrous nature and petrographic setting of the iddingsite clearly suggest an aqueous origin. These inferences are both consistent, however, with deposition of the iddingsite originally as a silicate gel, which then crystallized (neoformed) nearly isochemically. The iddingsite contains significantly more magnesium than implied by the model, which may suggest that the altering solutions were rich in Mg(2+).

  1. Preface to bLithium isotope geochemistryQ The use of light stable isotopes to elucidate Earth

    E-print Network

    Rudnick, Roberta L.

    Earth processes dates to the pioneering work of Harold Urey, who was awarded the Nobel prize as a function of temperature. Perhaps less well known, Urey was also one of the first to delve into lithium isotope geochemistry. Taylor and Urey (1938) used ion exchange chromatography to sepa- rate 6 Li from 7 Li

  2. Z .Earth and Planetary Science Letters 146 1997 475488 Geochemistry of gabbro sills in the crustmantle transition zone

    E-print Network

    Z .Earth and Planetary Science Letters 146 1997 475­488 Geochemistry of gabbro sills in the crust and compositions very similar to those in modally layered gabbros that form the lower part of the gabbro section in the ophiolite, and different from those in non-layered gabbros near the dike­gabbro transition. The presence

  3. Light element geochemistry of the Apollo 12 site

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Kaplan, I. R.; Kung, C. C.; Winter, D. A.; Friedman, D. L.; Desmarais, D. J.

    1978-01-01

    Analytical techniques of improved sensitivity have revealed details of the concentrations and isotopic compositions of light elements for a comprehensive suite of samples from the Apollo 12 regolith. These samples show a wide spread in maturity, although maximum contents observed for solar wind elements are less than observed at other sites, possibly reflecting relative recency of craters at the Apollo 12 site. Isotopic composition of nitrogen is consistent with the idea that N-15/N-14 in the solar wind has increased with time, at least a major part of this increase having occurred in the past 3.1 Gyr. Sulfur isotope systematics support a model in which sulfur is both added to the regolith, by meteoritic influx, and lost, by an isotopically selective process. Most soils from this site are heavily contaminated with terrestrial carbon.

  4. Rare Earth Element Interferences in Collision Cell and Standard

    E-print Network

    Rare Earth Element Interferences in Collision Cell and Standard Mode ICP-MS Analyses of Arsenic the idea that Rare Earth Elements are rare 2.Look at the extent of the Rare Earth Element interference this interference challenge Overview: #12;Rare Earth Technology Application(s) REE required Catalysts ·Oil

  5. Rare earth element systematics in hydrothermal fluids

    SciTech Connect

    Michard, A. )

    1989-03-01

    Rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge. The measured abundances show that hydrothermal activity is not expected to affect the REE balance of either continental or oceanic rocks. The REE enrichment of the solutions increases when the pH decreases. High-temperature solutions (> 230{degree}C) percolating through different rock types may show similar REE patterns.

  6. [In Situ Analysis of Element Geochemistry in Submarine Basalt in Hydrothermal Areas from Ultraslow Spreading Southwest Indian Ridge].

    PubMed

    Wang, Yan; Sun, Xiao-ming; Xu, Li; Liang, Ye-heng; Wu, Zhong-wei; Fu, Yu; Huang, Yi

    2015-03-01

    In this study, we analyze element geochemistry of submarine basalt in situ, which is sampled in hydrothermal areas from ultraslow spreading Southwest Indian Ridge, including the fresh basalt rocks (B19-9, B15-13) and altered basalt (B5-2). And we can confirm that altered mineral in B5-2 is celadonite by microscope and Raman Spectrum. Furthermore, amygdaloidal celadonites are analyzed by electron microprobe (EPMA) and EDS-line scanning. The results show that K-contents decrease and Na-contents increase from the core to the edge in these altered minerals, indicating the transition from celadonite to saponite. Celadonite is an altered minerals, forming in low temperature (< 50 degrees C) and oxidizing condition, while saponite form in low water/rock and more reducing condition. As a result, the transition from celadonite to saponite suggests environment change from oxidizing to reducing condition. Using the result of EPMA as internal standard, we can analyze rare earth elements (REE) in altered mineral in situ. Most of result show positive Eu anomaly (?(Eu)), indicating hydrothermal fluid transform from oxidizing to reducing, and reducing fluid rework on the early altered minerals. Comparison with REE in matrix feldspar both in altered and unaltered zoning, we find that reducing fluid can leach REE from the matrix feldspar, leading to lower total REE concentrations and positive Eu anomaly. So leaching process play an important role in hydrothermal system. PMID:26117900

  7. Note: Portable rare-earth element analyzer using pyroelectric crystal

    SciTech Connect

    Imashuku, Susumu Fuyuno, Naoto; Hanasaki, Kohei; Kawai, Jun

    2013-12-15

    We report a portable rare-earth element analyzer with a palm-top size chamber including the electron source of a pyroelectric crystal and the sample stage utilizing cathodoluminescence (CL) phenomenon. The portable rare-earth element analyzer utilizing CL phenomenon is the smallest reported so far. The portable rare-earth element analyzer detected the rare-earth elements Dy, Tb, Er, and Sm of ppm order in zircon, which were not detected by scanning electron microscopy-energy dispersive X-ray spectroscopy analysis. We also performed an elemental mapping of rare-earth elements by capturing a CL image using CCD camera.

  8. Geochemistry of U and Th and its Influence on the Origin and Evolution of the Crust of Earth and the Biological Evolution

    E-print Network

    Xuezhao Bao; Ali Zhang

    2007-10-16

    We have investigated the migration behaviors of uranium (U) and thorium (Th) in Earth and other terrestrial planets. Theoretical models of U and Th migration have been proposed. These models suggest that the unique features of Earth are closely connected with its unique U and Th migration models and distribution patterns. In the Earth, U and Th can combine with oxidative volatile components and water, migrate up to the asthenosphere position to form an enrichment zone (EZ) of U and Th first, and then migrate up further to the crusts through magmatism and metamorphism. We emphasize that the formation of an EZ of U, Th and other heat-producing elements is a prerequisite for the formation of a plate tectonic system. The heat-producing elements, currently mainly U and Th, in the EZ are also the energy sources that drive the formation and evolution of the crust of Earth and create special granitic continental crusts. In other terrestrial planets, including Mercury, Venus, and Mars, an EZ can not be formed because of a lack of oxidative volatile components and water. For this reason, a plate tectonic system can not been developed in these planets. We also emphasize the influence of U and Th in EZ on the development and evolution of life on Earth. We propose that since the Earth and planets were born in a united solar system, there should be some common mechanisms to create the similarities and differences between them. We have tried to develop an integrated view to explain some problems in the tectonics of Earth and evolution, bio-evolution, and planetary dynamics through U and Th geochemistry. We believe that a comprehensive exploration on energy sources and their evolution is a good way to build bridges between different disciplines of science in order to better understand the Earth and planets.

  9. Anthropogenic Cycles of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Du, X.; Graedel, T. E.

    2009-12-01

    This research will develop quantitatively resolved anthropogenic cycles and in-use stocks for the rare earth metals specifically cerium, lanthanum and dysprosium in Japan, China, and the U.S. for the year of 2007. Rare earth elements (REE) is a group of 17 scare metals widely used in a growing number of emerging technologies and have been in high demand for emerging technologies as raw materials during past the three decades. New market participants from newly industrializing countries, primarily China, have had strong impacts on the demand of share. Consequently, the importance to sustain a reliable, steady, uninterrupted supply on global market triggered comprehensive research to recognize and understand the life cycles of rare earths. Moreover, because China plays a dominant role in mining production since 1990, it requires the assessment for the countries, which are almost completely dependent on imports from China with respect to rare earth resources. The study aims to analyze the flows and stocks of rare earth elements individually as elemental form in spite of their natural geological co-occurrence and mixed composition in applications. By applying the method of Material Flow Analysis (MFA) work has been done on evaluating current and historical flows of specific technologically significant materials, for example, copper, zinc, nickel, etc., determining the stocks available in different types of reservoirs (e.g., lithosphere, in-use) and the flows among the reservoirs, developing scenarios of possible futures of metal use, and assessing the environmental and policy implications of the results. Therefore, REE as a new target deserves inclusion because of its potential demand-supply conflict and importance to secure the competitive advantage of technical innovation in future. This work will generate a quantitatively resolved anthropogenic life cycle and in-use stocks for REE for the main target countries for a chosen year, 2007, providing flows and stocks from mining to use to recycling quantifying the cycles for Japan, China and the U.S. as three representative types of consumers and paying attention to aspects of resource sustainability. Being well aware of the stages in the metal life cycle helps the sustainable development and policy making in long term. The goal is to consider REE resource availability, sustainability, and development strategies in the future that can sustain a reliable, steady, uninterrupted REE supply on the global market.

  10. Tipping elements in the Earth's climate system

    PubMed Central

    Lenton, Timothy M.; Held, Hermann; Kriegler, Elmar; Hall, Jim W.; Lucht, Wolfgang; Rahmstorf, Stefan; Schellnhuber, Hans Joachim

    2008-01-01

    The term “tipping point” commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term “tipping element” to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points. PMID:18258748

  11. Normalized rare earth elements in water, sediments, and wine: identifying sources and environmental redox conditions

    USGS Publications Warehouse

    Piper, David Z.; Bau, Michael

    2013-01-01

    The concentrations of the rare earth elements (REE) in surface waters and sediments, when normalized on an element-by-element basis to one of several rock standards and plotted versus atomic number, yield curves that reveal their partitioning between different sediment fractions and the sources of those fractions, for example, between terrestrial-derived lithogenous debris and seawater-derived biogenous detritus and hydrogenous metal oxides. The REE of ancient sediments support their partitioning into these same fractions and further contribute to the identification of the redox geochemistry of the sea water in which the sediments accumulated. The normalized curves of the REE that have been examined in several South American wine varietals can be interpreted to reflect the lithology of the bedrock on which the vines may have been grown, suggesting limited fractionation during soil development.

  12. Trace-element geochemistry of coal resource development related to environmental quality and health

    SciTech Connect

    Not Available

    1980-01-01

    This report assesses for decision makers and those involved in coal resource development the environmental and health impacts of trace-element effects arising from significant increases in the use of coal, unless unusual precautions are invoked. Increasing demands for energy and the pressing need for decreased dependence of the United States on imported oil require greater use of coal to meet the nation's energy needs during the next decade. If coal production and consumption are increased at a greatly accelerated rate, concern arises over the release, mobilization, transportation, distribution, and assimilation of certain trace elements, with possible adverse effects on the environment and human health. It is, therefore, important to understand their geochemical pathways from coal and rocks via air, water, and soil to plants, animals, and ultimately humans, and their relation to health and disease. To address this problem, the Panel on Trace Element Geochemistry of Coal Resource Development Related to Health (PECH) was established. Certain assumptions were made by the Panel to highlight the central issues of trace elements and health and to avoid unwarranted duplication of other studies. Based on the charge to the Panel and these assumptions, this report describes the amounts and distribution of trace elements related to the coal source; the various methods of coal extraction, preparation, transportation, and use; and the disposal or recycling of the remaining residues or wastes. The known or projected health effects are discussed at the end of each section.

  13. Alkali element depletion by core formation and vaporization on the early Earth

    NASA Technical Reports Server (NTRS)

    Lodders, K.; Fegley, B., Jr.

    1994-01-01

    The depletion of Na, K, Rb, and Cs in the Earth's upper mantle and crust relative to their abundances in chondrites is a long standing problem in geochemistry. Here we consider two commonly invoked mechanisms, namely core formation, and vaporization, for producing the observed depletions. Our models predict that a significant percentage of the Earth's bulk alkali element inventory is in the core (30 percent for Na, 52 percent for K, 74 percent for Rb, and 92 percent for Cs). These predictions agree with independent estimates from nebular volatility trends and (for K) from terrestrial heat flow data. Our models also predict that vaporization and thermal escape during planetary accretion are unlikely to produce the observed alkali element depletion pattern. However, loss during the putative giant impact which formed the Moon cannot be ruled out. Experimental, observational, and theoretical tests of our predictions are also described. Alkali element partitioning into the Earth's core was modeled by assuming that alkali element partitioning during core formation on the aubrite parent body (APB) is analogous to that on the early Earth. The analogy is reasonable for three reasons. First, the enstatite meteorites are the only known meteorites with the same oxygen isotope systematics as the Earth-Moon system. Second, the large core size of the Earth and the V depletion in the mantle requires accretion from planetesimals as reduced as the enstatite chondrites. Third, experimental studies of K partitioning between silicate and metal plus sulfide show that more K goes into the metal plus sulfide at higher pressures than at one atmosphere pressure. Thus partitioning in the relatively low pressure natural laboratory of the APB is a good guide to alkali elemental partitioning during the growth of the Earth.

  14. Catalog of Mount St. Helens 2004 - 2005 Tephra Samples with Major- and Trace-Element Geochemistry

    USGS Publications Warehouse

    Rowe, Michael C.; Thornber, Carl R.; Gooding, Daniel J.; Pallister, John S.

    2008-01-01

    This open-file report presents a catalog of information about 135 ash samples along with geochemical analyses of bulk ash, glass and individual mineral grains from tephra deposited as a result of volcanic activity at Mount St. Helens, Washington, from October 1, 2004 until August 15, 2005. This data, in conjunction with that in a companion report on 2004?2007 Mount St. Helens dome samples by Thornber and others (2008a) are presented in support of the contents of the U.S. Geological Survey Professional Paper 1750 (Sherrod and others, ed., 2008). Readers are referred to appropriate chapters in USGS Professional Paper 1750 for detailed narratives of eruptive activity during this time period and for interpretations of sample characteristics and geochemical data presented here. All ash samples reported herein are currently archived at the David A. Johnston Cascades Volcano Observatory in Vancouver, Washington. The Mount St. Helens 2004?2005 Tephra Sample Catalogue along with bulk, glass and mineral geochemistry are tabulated in 6 worksheets of the accompanying Microsoft Excel file, of2008-1131.xls. Samples in all tables are organized by collection date. Table 1 is a detailed catalog of sample information for tephra deposited downwind of Mount St. Helens between October 1, 2004 and August 18, 2005. Table 2 provides major- and trace-element analyses of 8 bulk tephra samples collected throughout that interval. Major-element compositions of 82 groundmass glass fragments, 420 feldspar grains, and 213 mafic (clinopyroxene, amphibole, hypersthene, and olivine) mineral grains from 12 ash samples collected between October 1, 2004 and March 8, 2005 are presented in tables 3 through 5. In addition, trace-element abundances of 198 feldspars from 11 ash samples (same samples as major-element analyses) are provided in table 6. Additional mineral and bulk ash analyses from 2004 and 2005 ash samples are published in chapters 30 (oxide thermometry; Pallister and others, 2008), 32 (amphibole major elements; Thornber and others, 2008b) and 37 (210Pb; 210Pb/226Pa; Reagan and others, 2008) of U.S. Geological Survey Professional Paper 1750 (Sherrod and others, 2008). A brief overview of sample collection methods is given below as an aid to deciphering the tephra sample catalog. This is followed by an explanation of the categories of sample information (column headers) in table 1. A summary of the analytical methods used to obtain the geochemical data in this report introduces the presentation of major- and trace-element geochemistry of Mount St. Helens 2004?2005 tephra samples in tables 2?6. Rhyolite glass standard analyses are reported (Appendix 1) to demonstrate the accuracy and precision of similar glass analyses presented herein.

  15. 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).

  16. Teflon-HPLC: A novel chromatographic system for application to isotope geochemistry and other industries

    E-print Network

    Teflon-HPLC: A novel chromatographic system for application to isotope geochemistry and other Keywords: Chromatography HPLC HDEHP Rare-earth elements Ni isotopes Isotope geochemistry Traditional column a gradient. Likewise, most existing high-performance liquid chromatography (HPLC) systems are not amenable

  17. Alkali element constraints on Earth-Moon relations

    NASA Technical Reports Server (NTRS)

    Norman, M. D.; Drake, M. J.; Jones, J. H.

    1994-01-01

    Given their range of volatilities, alkali elements are potential tracers of temperature-dependent processes during planetary accretion and formation of the Earth-Moon system. Under the giant impact hypothesis, no direct connection between the composition of the Moon and the Earth is required, and proto-lunar material does not necessarily experience high temperatures. Models calling for multiple collisions with smaller planetesimals derive proto-lunar materials mainly from the Earth's mantle and explicitly invoke vaporization, shock melting and volatility-related fractionation. Na/K, K/Rb, and Rb/Cs should all increase in response to thermal volatization, so theories which derive the Moon substantially from Earth's mantle predict these ratios will be higher in the Moon than in the primitive mantle of the Earth. Despite the overall depletion of volatile elements in the Moon, its Na/K and K/Rb are equal to or less than those of Earth. A new model presented here for the composition of Earth's continental crust, a major repository of the alkali elements, suggests the Rb/Cs of the Moon is also less than that of Earth. Fractionation of the alkali elements between Earth and Moon are in the opposite sense to predictions based on the relative volatilities of these elements, if the Moon formed by high-T processing of Earth's mantle. Earth, rather than the Moon, appears to carry a signature of volatility-related fractionation in the alkali elements. This may reflect an early episode of intense heating on Earth with the Moon's alkali budget accreting from cooler material.

  18. Volcanism in the Sumisu Rift, I. Major element, volatile, and stable isotope geochemistry

    USGS Publications Warehouse

    Hochstaedter, A.G.; Gill, J.B.; Kusakabe, M.; Newman, S.; Pringle, M.; Taylor, B.; Fryer, P.

    1990-01-01

    A bimodal volcanic suite with KAr ages of 0.05-1.40 Ma was collected from the Sumisu Rift using alvin. These rocks are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, and provide a present day example of volcanism associated with arc rifting and back-arc basin initiation. Major element geochemistry of the basalts is most similar to that of basalts found in other, more mature back-arc basins, which indicates that back-arc basins need not begin their magmatic evolution with lavas bearing strong arc signatures. Volatile concentrations distinguish Sumisu Rift basalts from island arc basalts and MORB. H2O contents, which are at least four times greater than in MORB, suppress plagioclase crystallization. This suppression results in a more mafic fractionating assemblage, which prevents Al2O3 depletion and delays the initiation of Fe2O3(tot) and TiO2 enrichment. However, unlike arc basalts, Fe3+ ??Fe ratios are only slightly higher than in MORB and are insufficient to cause magnetite saturation early enough to suppress Fe2O3(tot) and TiO2 enrichment. Thus, major element trends are more similar to those of MORB than arcs. H2O, CO2 and S are undersaturated relative to pure phase solubility curves, indicating exsolution of an H2O-rich mixed gas phase. High H2O S, high ??D, and low (MORB-like) ??34S ratios are considered primary and distinctive of the back-arc basin setting. ?? 1990.

  19. Earth, Air, Fire and Water in Our Elements

    ERIC Educational Resources Information Center

    Lievesley, Tara

    2007-01-01

    The idea that everything is made of the four "elements", earth, air, fire and water, goes back to the ancient Greeks. In this article, the author talks about the origins of ideas about the elements. The author provides an account that attempts to summarise thousands of years of theoretical development of the elements in a thousand words or so.

  20. MaRGEE: Move and Rotate Google Earth Elements

    NASA Astrophysics Data System (ADS)

    Dordevic, Mladen M.; Whitmeyer, Steven J.

    2015-12-01

    Google Earth is recognized as a highly effective visualization tool for geospatial information. However, there remain serious limitations that have hindered its acceptance as a tool for research and education in the geosciences. One significant limitation is the inability to translate or rotate geometrical elements on the Google Earth virtual globe. Here we present a new JavaScript web application to "Move and Rotate Google Earth Elements" (MaRGEE). MaRGEE includes tools to simplify, translate, and rotate elements, add intermediate steps to a transposition, and batch process multiple transpositions. The transposition algorithm uses spherical geometry calculations, such as the haversine formula, to accurately reposition groups of points, paths, and polygons on the Google Earth globe without distortion. Due to the imminent deprecation of the Google Earth API and browser plugin, MaRGEE uses a Google Maps interface to facilitate and illustrate the transpositions. However, the inherent spatial distortions that result from the Google Maps Web Mercator projection are not apparent once the transposed elements are saved as a KML file and opened in Google Earth. Potential applications of the MaRGEE toolkit include tectonic reconstructions, the movements of glaciers or thrust sheets, and time-based animations of other large- and small-scale geologic processes.

  1. Modeling rammed earth wall using discrete element method

    NASA Astrophysics Data System (ADS)

    Bui, T.-T.; Bui, Q.-B.; Limam, A.; Morel, J.-C.

    2015-07-01

    Rammed earth is attracting renewed interest throughout the world thanks to its "green" characteristics in the context of sustainable development. Several research studies have thus recently been carried out to investigate this material. Some of them attempted to simulate the rammed earth's mechanical behavior by using analytical or numerical models. Most of these studies assumed that there was a perfect cohesion at the interface between earthen layers. This hypothesis proved to be acceptable for the case of vertical loading, but it could be questionable for horizontal loading. To address this problem, discrete element modeling seems to be relevant to simulate a rammed earth wall. To our knowledge, no research has been conducted thus far using discrete element modeling to study a rammed earth wall. This paper presents an assessment of the discrete element modeling's robustness for rammed earth walls. Firstly, a brief description of the discrete element modeling is presented. Then the parameters necessary for discrete element modeling of the material law of the earthen layers and their interfaces law following the Mohr-Coulomb model with a tension cut-off and post-peak softening were given. The relevance of the model and the material parameters were assessed by comparing them with experimental results from the literature. The results showed that, in the case of vertical loading, interfaces did not have an important effect. In the case of diagonal loading, model with interfaces produced better results. Interface characteristics can vary from 85 to 100% of the corresponding earthen layer's characteristics.

  2. Systematic variation of rare-earth elements in cerium-earth minerals

    USGS Publications Warehouse

    Murata, K.J.; Rose, H.J., Jr.; Carron, M.K.; Glass, J.J.

    1957-01-01

    In a continuation of a study reported previously, rare-earth elements and thorium have been determined in monazite, allanite, cerite, bastnaesite, and a number of miscellaneous cerium-earth minerals. A quantity called sigma (???), which is the sum of the atomic percentages of La, Ce, and Pr, is proposed as an index of composition of all cerium-earth minerals with respect to the rare-earth elements. The value of ??? for all of the minerals analysed falls between 58 and 92 atomic per cent. Monazites, allanites, and cerites cover the entire observed range, whereas bastnaesites are sharply restricted to the range between 80 and 92 atomic per cent. The minimum value of ??? for a cerium-earth mineral corresponds to the smallest possible unit-cell size of the mineral. In monazite, this structurally controlled minimum value of ??? is estimated to be around 30 atomic per cent. Neodymium, because of its abundance, and yttrium, because of its small size, have dominant roles in contraction of the structure. In the other direction, the limit of variation in composition will be reached when lanthanum becomes the sole rare-earth element in a cerium-earth mineral. Cerium-earth minerals from alkalic rocks are all characterized by values of ??? greater than 80 atomic per cent, indicating that the processes that formed these rocks were unusually efficient in fractionating the rare-earth elements-efficient in the sense that a highly selected assemblage is produced without eliminating the bulk of these elements. Analyses of inner and outer parts of two large crystals of monazite from different deposits show no difference in ??? in one crystal and a slightly smaller value of ??? in the outer part of the other crystal compared to the inner part. The ??? of monazites from pegmatites that intrude genetically related granitic rocks in North Carolina is found to be either higher or lower than the ??? of monazites in the intruded host rock. These results indicate that the fractionation of the rare-earth elements is not a simple unidirectional process. When a cerium-earth mineral undergoes replacement, its rare-earth elements may be fractionated into two parts, one forming a new mineral with ??? that is smaller, and the other a second new mineral with ??? that is larger than that of the original mineral. The complete analysis of a cerium-earth mineral to determine its ??? is time consuming. The discovery of a direct relationship between ??? and the Ce/(Nd + Y) atomic ratio in cerium earth minerals allows a rapid determination of ??? from spectrograms obtained in a previously described method for determining thorium in these minerals. ?? 1957.

  3. Rare earth elements in synthetic zircon. 1. synthesis, and rare earth element and phosphorus doping.

    SciTech Connect

    Hanchar, J. M.; Finch, R. J.; Hoskin, W. O.; Watson, E. B.; Cherniak, D. J.; Mariano, A. N.; Chemical Engineering; George Washington Univ.; Univ. of Canterbury; Australian National Univ.; Rensselaer Polytechnic Inst.

    2001-05-01

    Sedimentary mineral assemblages commonly contain detrital zircon crystals as part of the heavy-mineral fraction. Age spectra determined by U-Pb isotopic analysis of single zircon crystals within a sample may directly image the age composition--but not the chemical composition--of the source region. Rare earth element (REE) abundances have been measured for zircons from a range of common crustal igneous rock types from different tectonic environments, as well as kimberlite, carbonatite, and high-grade metamorphic rocks, to assess the potential of using zircon REE characteristics to infer the rock types present in sediment source regions. Except for zircon with probable mantle affinities, zircon REE abundances and normalized patterns show little intersample and intrasample variation. To evaluate the actual variation in detrital zircon REE composition in a true sediment of known mixed provenance, zircons from a sandstone sample from the Statfjord Formation (North Sea) were analyzed. Despite a provenance including high-grade metasediment and granitoids and a range in zircon age of 2.82 b.y., the zircon REEs exhibit a narrow abundance range with no systematic differences in pattern shape. These evidences show zircon REE patterns and abundances are generally not useful as indicators of provenance.

  4. Trace element geochemistry of groundwater in a karst subterranean estuary (Yucatan Peninsula, Mexico)

    NASA Astrophysics Data System (ADS)

    Gonneea, Meagan Eagle; Charette, Matthew A.; Liu, Qian; Herrera-Silveira, Jorge A.; Morales-Ojeda, Sara M.

    2014-05-01

    Trace element cycling within subterranean estuaries frequently alters the chemical signature of groundwater and may ultimately control the total chemical load to the coastal ocean associated with submarine groundwater discharge. Globally, karst landscapes occur over 12% of all coastlines. Subterranean estuaries in these regions are highly permeable, resulting in rapid infiltration of precipitation and transport of groundwater to the coast, and the predominant carbonate minerals are readily soluble. We studied the chemical cycling of barium (Ba), strontium (Sr), manganese (Mn), uranium (U), calcium (Ca) and radium (Ra) within the carbonate karst subterranean estuary of the Yucatan Peninsula, which is characterized by a terrestrial groundwater lens overlying marine groundwater intrusion with active submarine discharge through coastal springs. Terrestrial groundwater calcium (1-5 mmol kg-1) and alkalinity (3-8 mmol kg-1) are enriched over that predicted by equilibrium between recharging precipitation and calcite, which can be accounted for by groundwater organic matter respiration and subsequent dissolution of calcite, dolomite and gypsum. There is a close agreement between the observed terrestrial groundwater Sr/Ca, Mn/Ca, Ba/Ca and Ra/Ca and that predicted by equilibrium dissolution of calcite, thus the trace element content of terrestrial groundwater is largely determined by mineral dissolution. Subsequent mixing between terrestrial groundwater and the ocean within the actively discharging springs is characterized by conservative mixing of Sr, Mn, Ba and Ca, while U is variable and Ra displays a large enrichment (salinity: 1.9-34.9, Ba: 60-300 nmol kg-1, Sr: 15-110 ?mol kg-1, U: 0.3-35 nmol kg-1, Mn: 0.3-200 nmol kg-1, Ca: 4.3-12.9 mmol kg-1, 226Ra: 18-2140 dpm 100 L-1). The deep groundwater sampled through cenotes, local dissolution features, is typified by elevated Ba, Sr, Ca, Mn and Ra and the absence of U within marine groundwater, due to enhanced dissolution of the aquifer matrix following organic matter degradation and redox processes including sulfate reduction (salinity: 0.2-36.6, Ba: 7-1630 nmol kg-1, Sr: 1.3-210 ?mol kg-1, U: 0.3-18 nmol kg-1, Mn: 0.6-2600 nmol kg-1, Ca: 2.1-15.2 mmol kg-1, 226Ra 20-5120 dpm 100 L-1). However, there is no evidence in the spring geochemistry that deep marine groundwater within this reaction zone exchanges with the coastal ocean via spring discharge. Total submarine groundwater discharge rates calculated from radium tracers are 40-95 m3 m-1 d-1, with terrestrial discharge contributing 75 ± 25% of the total. Global estimates of chemical loading from karst subterranean estuaries suggest Sr and U fluxes are potentially 15-28% and 7-33% of total ocean inputs (8.2-15.3 mol y-1 and 4.0-7.7 mol y-1), respectively. Radium-226 inputs from karst subterranean estuaries are 34-50 times river inputs (6.7-9.9 × 1016 dpm y-1).

  5. Anthropogenic influence on trace element geochemistry of healing mud (peloid) from Makirina Cove (Croatia)

    NASA Astrophysics Data System (ADS)

    Miko, S.; Koch, G.; Mesi?, S.; Šparica-Miko, M.; Šparica, M.; ?epelak, R.; Ba?ani, A.; Vre?a, P.; Dolenec, T.; Bergant, S.

    2008-08-01

    Due to their balneotherapeutic features, the organic-rich sediments in Makirina Cove are an important source of healing mud. An environmental geochemistry approach using normalization techniques was applied to evaluate the anthropogenic contribution of trace metals to sediments used as healing mud. Sediment geochemistry was found to be associated with land-use change and storm events, as well as with proximity of a road with heavy traffic in the summer months. Local valley topography preferentially channels lithogenic and pollutant transport to the cove. Concentrations and distribution of trace metals indicate lithogenic (Ni, Cr, Co) and anthropogenic (Pb, Cu, Zn and Se) contributions to the sediments. The calculation of enrichment factors indicates a moderate (EFs between 2-3.5) input of anthropogenic Cu and Pb in surficial sediments to a depth of 10 cm. Patients using the Makirina Cove sediments as healing mud could be to some extent exposed to enhanced uptake of metals from anthropogenic sources via dermal contact.

  6. Determination of thorium and of rare earth elements in cerium earth minerals and ores

    USGS Publications Warehouse

    Carron, M.K.; Skinner, D.L.; Stevens, R.E.

    1955-01-01

    The conventional oxalate method for precipitating thorium and the rare earth elements in acid solution exhibits definite solubilities of these elements. The present work was undertaken to establish conditions overcoming these solubilities and to find optimum conditions for precipitating thorium and the rare earth elements as hydroxides and sebacates. The investigations resulted in a reliable procedure applicable to samples in which the cerium group elements predominate. The oxalate precipitations are made from homogeneous solution at pH 2 by adding a prepared solution of anhydrous oxalic acid in methanol instead of the more expensive crystalline methyl oxalate. Calcium is added as a carrier. Quantitative precipitation of thorium and the rare earth elements is ascertained by further small additions of calcium to the supernatant liquid, until the added calcium precipitates as oxalate within 2 minutes. Calcium is removed by precipitating the hydroxides of thorium and rare earths at room temperature by adding ammonium hydroxide to pH > 10. Thorium is separated as the sebacate at pH 2.5, and the rare earths are precipitated with ammonium sebacate at pH 9. Maximum errors for combined weights of thorium and rare earth oxides on synthetic mixtures are ??0.6 mg. Maximum error for separated thoria is ??0.5 mg.

  7. Distribution and geochemistry of selected trace elements in the Sacramento River near Keswick Reservoir

    USGS Publications Warehouse

    Antweiler, Ronald C.; Taylor, Howard E.; Alpers, Charles N.

    2012-01-01

    The effect of heavy metals from the Iron Mountain Mines (IMM) Superfund site on the upper Sacramento River is examined using data from water and bed sediment samples collected during 1996-97. Relative to surrounding waters, aluminum, cadmium, cobalt, copper, iron, lead, manganese, thallium, zinc and the rare-earth elements (REE) were all present in high concentrations in effluent from Spring Creek Reservoir (SCR), which enters into the Sacramento River in the Spring Creek Arm of Keswick Reservoir. SCR was constructed in part to regulate the flow of acidic, metal-rich waters draining the IMM Superfund site. Although virtually all of these metals exist in SCR in the dissolved form, upon entering Keswick Reservoir they at least partially converted via precipitation and/or adsorption to the particulate phase. In spite of this, few of the metals settled out; instead the vast majority was transported colloidally down the Sacramento River at least to Bend Bridge, 67 km from Keswick Dam. The geochemical influence of IMM on the upper Sacramento River was variable, chiefly dependent on the flow of Spring Creek. Although the average flow of the Sacramento River at Keswick Dam is 250 m3/s (cubic meters per second), even flows as low as 0.3 m3/s from Spring Creek were sufficient to account for more than 15% of the metals loading at Bend Bridge, and these proportions increased with increasing Spring Creek flow. The dissolved proportion of the total bioavailable load was dependent on the element but steadily decreased for all metals, from near 100% in Spring Creek to values (for some elements) of less than 1% at Bend Bridge; failure to account for the suspended sediment load in assessments of the effect of metals transport in the Sacramento River can result in estimates which are low by as much as a factor of 100.

  8. Major and trace element geochemistry of Lake Bogoria and Lake Nakuru, Kenya, during extreme draught

    PubMed Central

    Jirsa, Franz; Gruber, Martin; Stojanovic, Anja; Omondi, Steve Odour; Mader, Dieter; Körner, Wilfried; Schagerl, Michael

    2013-01-01

    The physico-chemical properties of water samples from the two athalassic endorheic lakes Bogoria and Nakuru in Kenya were analysed. Surface water samples were taken between July 2008 and October 2009 in weekly intervals from each lake. The following parameters were determined: pH, salinity, electric conductivity, dissolved organic carbon (DOC), the major cations (FAAS and ICP-OES) and the major anions (IC), as well as certain trace elements (ICP-OES). Samples of superficial sediments were taken in October 2009 and examined using Instrumental Neutron Activation Analysis (INAA) for their major and trace element content including rare earth elements (REE). Both lakes are highly alkaline with a dominance of Na > K > Si > Ca in cations and HCO3 > CO3 > Cl > F > SO4 in anions. Both lakes also exhibited high concentrations of Mo, As and fluoride. Due to an extreme draught from March to October 2009, the water level of Lake Nakuru dropped significantly. This created drastic evapoconcentration, with the total salinity rising from about 20‰ up to 63‰. Most parameters (DOC, Na, K, Ca, F, Mo and As) increased with falling water levels. A clear change in the quality of DOC was observed, followed by an almost complete depletion of dissolved Fe from the water phase. In Lake Bogoria the evapoconcentration effects were less pronounced (total salinity changed from about 40‰ to 48‰). The distributions of REE in the superficial sediments of Lake Nakuru and Lake Bogoria are presented here for the first time. The results show a high abundance of the REE and a very distinct Eu depletion of Eu/Eu* = 0.33–0.45. PMID:25843965

  9. Multi-objective optimization of chromatographic rare earth element separation.

    PubMed

    Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

    2015-10-16

    The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium. PMID:26375205

  10. Trace-element geochemistry of metabasaltic rocks from the Yukon-Tanana Upland and implications for the origin of tectonic assemblages in east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, C.; Cooper, K.M.

    1999-01-01

    We present major- and trace- element geochemical data for 27 amphibolites and six greenstones from three structural packages in the Yukon-Tanana Upland of east-central Alaska: the Lake George assemblage (LG) of Devono-Mississippian augen gneiss, quartz-mica schist, quartzite, and amphibolite; the Taylor Mountain assemblage (TM) of mafic schist and gneiss, marble, quartzite, and metachert; and the Seventymile terrane of greenstone, serpentinized peridotite, and Mississippian to Late Triassic metasedimentary rocks. Most LG amphibolites have relatively high Nb, TiO2, Zr, and light rare earth element contents, indicative of an alkalic to tholeiitic, within-plate basalt origin. The within-plate affinities of the LG amphibolites suggest that their basaltic parent magmas developed in an extensional setting and support a correlation of these metamorphosed continental-margin rocks with less metamorphosed counterparts across the Tintina fault in the Selwyn Basin of the Canadian Cordillera. TM amphibolites have a tholeiitic or calc-alkalic composition, low normalized abundances of Nb and Ta relative to Th and La, and Ti/V values of <20, all indicative of a volcanic-arc origin. Limited results from Seventymile greenstones indicate a tholeiitic or calc-alkalic composition and intermediate to high Ti/V values (27-48), consistent with either a within-plate or an ocean-floor basalt origin. Y-La-Nb proportions in both TM and Seventymile metabasalts indicate the proximity of the arc and marginal basin to continental crust. The arc geochemistry of TM amphibolites is consistent with a model in which the TM assemblage includes arc rocks generated above a west-dipping subduction zone outboard of the North American continental margin in mid-Paleozoic through Triassic time. The ocean-floor or within-plate basalt geochemistry of the Seventymile greenstones supports the correlation of the Seventymile terrane with the Slide Mountain terrane in Canada and the hypothesis that these oceanic rocks originated in a basin between the continental margin and an arc to the west.

  11. Petrology and trace element geochemistry of Tissint, the newest shergottite fall

    NASA Astrophysics Data System (ADS)

    Balta, J. Brian; Sanborn, Matthew E.; Udry, Arya; Wadhwa, Meenakshi; McSween, Harry Y.

    2015-01-01

    AbstractThe fall and recovery of the Tissint meteorite in 2011 created a rare opportunity to examine a Martian sample with a known, short residence time on <span class="hlt">Earth</span>. Tissint is an olivine-phyric shergottite that accumulated olivine antecrysts within a single magmatic system. Coarse olivine grains with nearly homogeneous cores of Mg# >80 suggest slow re-equilibration. Many macroscopic features of this sample resemble those of LAR 06319, including the olivine crystal size distribution and the presence of evolved oxide and olivine compositions. Unlike LAR 06319, however, no magmatic hydrous phases were found in the analyzed samples of Tissint. Minor and trace <span class="hlt">element</span> compositions indicate that the meteorite is the product of closed-system crystallization from a parent melt derived from a depleted source, with no obvious addition of a LREE-rich (crustal?) component prior to or during crystallization. The whole-rock REE pattern is similar to that of intermediate olivine-phyric shergottite EETA 79001 lithology A, and could also be approximated by a more olivine-rich version of depleted basaltic shergottite QUE 94201. Magmatic oxygen fugacities are at the low end of the shergottite range, with log fO2 of QFM-3.5 to -4.0 estimated based on early-crystallized minerals and QFM-2.4 estimated based on the Eu in pyroxene oxybarometer. These values are similarly comparable to other depleted shergottites, including SaU 005 and QUE 94201. Tissint occupies a previously unsampled niche in shergottite chemistry: containing olivines with Mg# >80, resembling the enriched olivine-phyric shergottite LAR 06319 in its crystallization path, and comparable to intermediate olivine-phyric shergottite EETA 79001A, depleted olivine-phyric shergottite DaG 476, and depleted basaltic shergottite QUE 94201 in its trace <span class="hlt">element</span> abundances and oxygen fugacity. The apparent absence of evidence for terrestrial alteration in Tissint (particularly in trace <span class="hlt">element</span> abundances in the whole-rock and individual minerals) confirms that exposure to the arid desert environment results in only minimal weathering of samples, provided the exposure times are brief.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950030728&hterms=hotspot&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhotspot','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950030728&hterms=hotspot&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhotspot"><span id="translatedtitle">Spherical disharmonics in the <span class="hlt">Earth</span> sciences and the spatial solution: Ridges, hotspots, slabs, <span class="hlt">geochemistry</span> and tomography correlations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ray, Terrill W.; Anderson, Don L.</p> <p>1994-01-01</p> <p>There is increasing use of statistical correlations between geophysical fields and between geochemical and geophysical fields in attempts to understand how the <span class="hlt">Earth</span> works. Typically, such correlations have been based on spherical harmonic expansions. The expression of functions on the sphere as spherical harmonic series has many pitfalls, especially if the data are nonuniformly and/or sparsely sampled. Many of the difficulties involved in the use of spherical harmonic expansion techniques can be avoided through the use of spatial domain correlations, but this introduces other complications, such as the choice of a sampling lattice. Additionally, many geophysical and geochemical fields fail to satisfy the assumptions of standard statistical significance tests. This is especially problematic when the data values to be correlated with a geophysical field were collected at sample locations which themselves correlate with that field. This paper examines many correlations which have been claimed in the past between <span class="hlt">geochemistry</span> and mantle tomography and between hotspot, ridge, and slab locations and tomography using both spherical harmonic coefficient correlations and spatial domain correlations. No conclusively significant correlations are found between isotopic <span class="hlt">geochemistry</span> and mantle tomography. The Crough and Jurdy (short) hotspot location list shows statistically significant correlation with lowermost mantle tomography for degree 2 of the spherical harmonic expansion, but there are no statistically significant correlations in the spatial case. The Vogt (long) hotspot location list does not correlate with tomography anywhere in the mantle using either technique. Both hotspot lists show a strong correlation between hotspot locations and geoid highs when spatially correlated, but no correlations are revealed by spherical harmonic techniques. Ridge locations do not show any statistically significant correlations with tomography, slab locations, or the geoid; the strongest correlation is with lowermost mantle tomography, which is probably spurious. The most striking correlations are between mantle tomography and post-Pangean subducted slabs. The integrated locations of slabs correlate strongly with fast areas near the transition zone and the core-mantle boundary and with slow regions from 1022-1248 km depth. This seems to be consistent with the 'avalanching' downwellings which have been indicated by models of the mantle which include an endothermic phase transition at the 670-km discontinuity, although this is not a unique interpretation. Taken as a whole, these results suggest that slabs and associated cold downwellings are the dominant feature of mantle convection. Hotspot locations are no better correlated with lower mantle tomography than are ridge locations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25613802','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25613802"><span id="translatedtitle">Coal fly ash as a resource for rare <span class="hlt">earth</span> <span class="hlt">elements</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Franus, Wojciech; Wiatros-Motyka, Ma?gorzata M; Wdowin, Magdalena</p> <p>2015-06-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) have been recognised as critical raw materials, crucial for many clean technologies. As the gap between their global demand and supply increases, the search for their alternative resources becomes more and more important, especially for the countries which depend highly on their import. Coal fly ash (CFA), which when not utilised is considered waste, has been regarded as the possible source of many <span class="hlt">elements</span>, including REE. Due to the increase in the energy demand, CFA production is expected to grow, making research into the use of this material a necessity. As Poland is the second biggest coal consumer in the European Union, the authors have studied different coal fly ashes from ten Polish power plants for their rare <span class="hlt">earth</span> <span class="hlt">element</span> content. All the fly ashes have a broadly similar distribution of rear <span class="hlt">earth</span> <span class="hlt">elements</span>, with light REE being dominant. Most of the samples have REE content relatively high and according to Seredin and Dai (Int J Coal Geol 94: 67-93, 2012) classification can be considered promising REE raw materials. PMID:25613802</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23602698','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23602698"><span id="translatedtitle">Uncovering the end uses of the rare <span class="hlt">earth</span> <span class="hlt">elements</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Du, Xiaoyue; Graedel, T E</p> <p>2013-09-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are a group of fifteen <span class="hlt">elements</span> with unique properties that make them indispensable for a wide variety of emerging and conventional established technologies. However, quantitative knowledge of REE remains sparse, despite the current heightened interest in future availability of the resources. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supply vulnerable to short term disruption. We have drawn upon the published literature and unpublished materials in different languages to derive the first quantitative annual domestic production by end use of individual rare <span class="hlt">earth</span> <span class="hlt">elements</span> from 1995 to 2007. The information is illustrated in Sankey diagrams for the years 1995 and 2007. Other years are available in the supporting information. Comparing 1995 and 2007, the production of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> in China, Japan, and the US changed dramatically in quantities and structure. The information can provide a solid foundation for industries, academic institutions and governments to make decisions and develop strategies. PMID:23602698</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Sci...343C.386M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Sci...343C.386M"><span id="translatedtitle"><span class="hlt">Elemental</span> <span class="hlt">Geochemistry</span> of Sedimentary Rocks at Yellowknife Bay, Gale Crater, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McLennan, S. M.; Anderson, R. B.; Bell, J. F.; Bridges, J. C.; Calef, F.; Campbell, J. L.; Clark, B. C.; Clegg, S.; Conrad, P.; Cousin, A.; Des Marais, D. J.; Dromart, G.; Dyar, M. D.; Edgar, L. A.; Ehlmann, B. L.; Fabre, C.; Forni, O.; Gasnault, O.; Gellert, R.; Gordon, S.; Grant, J. A.; Grotzinger, J. P.; Gupta, S.; Herkenhoff, K. E.; Hurowitz, J. A.; King, P. L.; Le Mouélic, S.; Leshin, L. A.; Léveillé, R.; Lewis, K. W.; Mangold, N.; Maurice, S.; Ming, D. W.; Morris, R. V.; Nachon, M.; Newsom, H. E.; Ollila, A. M.; Perrett, G. M.; Rice, M. S.; Schmidt, M. E.; Schwenzer, S. P.; Stack, K.; Stolper, E. M.; Sumner, D. Y.; Treiman, A. H.; VanBommel, S.; Vaniman, D. T.; Vasavada, A.; Wiens, R. C.; Yingst, R. A.; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Minitti, Michelle; Cremers, David; Farmer, Jack; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; Blank, Jennifer; Weigle, Gerald; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Farley, Kenneth; Griffes, Jennifer; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Siebach, Kirsten; Brunet, Claude; Hipkin, Victoria; Marchand, Geneviève; Sánchez, Pablo Sobrón; Favot, Laurent; Cody, George; Steele, Andrew; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodríguez, Javier Caride; Blázquez, Isaías Carrasco; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jiménez, Mercedes Marín; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muñoz; López, Sara Navarro; Peinado-González, Verónica; Pla-García, Jorge; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio José; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, María-Paz Zorzano; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Kemppinen, Osku; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Bish, David; Schieber, Juergen; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; d'Uston, Claude; Lasue, Jérémie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Israël, Guy; Szopa, Cyril; Robert, François; Sautter, Violaine; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Edgett, Kenneth; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; Malin, Michael; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Van Beek, Tessa; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Summons, Roger; Goesmann, Fred; Goetz, Walter; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Fassett, Caleb; Blake, David F.; Bristow, Thomas; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Wilhelm, Mary Beth; Bleacher, Lora; Brinckerhoff, William; Choi, David; Dworkin, Jason P.; Eigenbrode, Jennifer; Floyd, Melissa; Freissinet, Caroline</p> <p>2014-01-01</p> <p>Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The <span class="hlt">geochemistry</span> of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24324274','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24324274"><span id="translatedtitle"><span class="hlt">Elemental</span> <span class="hlt">geochemistry</span> of sedimentary rocks at Yellowknife Bay, Gale crater, Mars.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McLennan, S M; Anderson, R B; Bell, J F; Bridges, J C; Calef, F; Campbell, J L; Clark, B C; Clegg, S; Conrad, P; Cousin, A; Des Marais, D J; Dromart, G; Dyar, M D; Edgar, L A; Ehlmann, B L; Fabre, C; Forni, O; Gasnault, O; Gellert, R; Gordon, S; Grant, J A; Grotzinger, J P; Gupta, S; Herkenhoff, K E; Hurowitz, J A; King, P L; Le Mouélic, S; Leshin, L A; Léveillé, R; Lewis, K W; Mangold, N; Maurice, S; Ming, D W; Morris, R V; Nachon, M; Newsom, H E; Ollila, A M; Perrett, G M; Rice, M S; Schmidt, M E; Schwenzer, S P; Stack, K; Stolper, E M; Sumner, D Y; Treiman, A H; VanBommel, S; Vaniman, D T; Vasavada, A; Wiens, R C; Yingst, R A</p> <p>2014-01-24</p> <p>Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The <span class="hlt">geochemistry</span> of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars. PMID:24324274</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026818','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026818"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> partitioning between hydrous ferric oxides and acid mine water during iron oxidation</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Verplanck, P.L.; Nordstrom, D.K.; Taylor, H.E.; Kimball, B.A.</p> <p>2004-01-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">element</span> (REE) <span class="hlt">geochemistry</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910060597&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910060597&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Compositional and phase relations among rare <span class="hlt">earth</span> <span class="hlt">element</span> minerals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burt, D. M.</p> <p>1990-01-01</p> <p>This paper discusses the compositional and phase relationships among minerals in which rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) occur as essential constituents (e.g., bastnaesite, monazite, xenotime, aeschynite, allanite). Particular consideration is given to the vector representation of complex coupled substitutions in selected REE-bearing minerals and to the REE partitioning between minerals as related to the acid-base tendencies and mineral stabilities. It is shown that the treatment of coupled substitutions as vector quantities facilitates graphical representation of mineral composition spaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://dspace.mit.edu/handle/1721.1/62493','EPRINT'); return false;" href="http://dspace.mit.edu/handle/1721.1/62493"><span id="translatedtitle">Primitive magmas of the <span class="hlt">Earth</span> and Moon : a petrologic investigation of magma genesis and evolution</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Barr, Jay Arthur</p> <p>2010-01-01</p> <p>Field studies, major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span>, isotopes, petrography, phase equilibrium experiments and thermodynamics are used investigate and understand primitive melts from the <span class="hlt">Earth</span> and the Moon. Chapter 1 ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://isotope.colorado.edu/~mojzsis/2012_Mloszewska_EPSL.pdf','EPRINT'); return false;" href="http://isotope.colorado.edu/~mojzsis/2012_Mloszewska_EPSL.pdf"><span id="translatedtitle">The composition of <span class="hlt">Earth</span>'s oldest iron formations: The Nuvvuagittuq Supracrustal Belt (Qubec, Canada)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Mojzsis, Stephen J.</p> <p></p> <p>The composition of <span class="hlt">Earth</span>'s oldest iron formations: The Nuvvuagittuq Supracrustal Belt (Québec 18 November 2011 Available online 29 December 2011 Editor: P. DeMenocal Keywords: banded iron formation Nuvvuagittuq Supracrustal Belt trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> Eoarchean Hadean seawater</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5563033','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5563033"><span id="translatedtitle">Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in hot brines (165 to 190 degree C) from the Salton Sea geothermal field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lepel, E.A.; Laul, J.C.; Smith, M.R.</p> <p>1988-01-01</p> <p>Rare-<span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations are important indicators for revealing various chemical fractionation processes (water/rock interactions) and source region <span class="hlt">geochemistry</span>. Since the REE patterns are characteristic of geologic materials (basalt, granite, shale, sediments, etc.) and minerals (K-feldspar, calcite, illite, epidote, etc.), their study in geothermal fluids may serve as a geothermometer. The REE study may also enable us to address the issue of groundwater mixing. In addition, the behavior of the REE can serve as analogs of the actinides in radioactive waste (e.g., neodymium is an analog of americium and curium). In this paper, the authors port the REE data for a Salton Sea Geothermal Field (SSGF) brine (two aliquots: port 4 at 165{degree}C and port 5 at 190{degree}C) and six associated core samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890011981','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890011981"><span id="translatedtitle">Trace <span class="hlt">element</span> and isotope <span class="hlt">geochemistry</span> of Cretaceous-Tertiary boundary sediments: identification of extra-terrestrial and volcanic components</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Margolis, S. V.; Doehne, E. F.</p> <p>1988-01-01</p> <p>Trace <span class="hlt">element</span> and stable isotope analyses were performed on a series of sediment samples crossing the Cretaceous-Tertiary (K-T) boundary from critical sections at Aumaya and Sopelano, Spain. The aim is to possibly distinguish extraterrestrial vs. volcanic or authigenic concentration of platinum group and other <span class="hlt">elements</span> in K-T boundary transitional sediments. These sediments also have been shown to contain evidence for step-wise extinction of several groups of marine invertebrates, associated with negative oxygen and carbon isotope excursions occurring during the last million years of the Cretaceous. These isotope excursions have been interpreted to indicate major changes in ocean thermal regime, circulation, and ecosystems that may be related to multiple events during latest Cretaceous time. Results to date on the petrographic and geochemical analyses of the Late Cretaceous and Early Paleocene sediments indicate that diagenesis has obviously affected the trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and stable isotope compositions at Zumaya. Mineralogical and geochemical analysis of K-T boundary sediments at Zumaya suggest that a substantial fraction of anomalous trace <span class="hlt">elements</span> in the boundary marl are present in specific mineral phases. Platinum and nickel grains perhaps represent the first direct evidence of siderophile-rich minerals at the boundary. The presence of spinels and Ni-rich particles as inclusions in aluminosilicate spherules from Zumaya suggests an original, non-diagenetic origin for the spherules. Similar spherules from southern Spain (Caravaca), show a strong marine authigenic overprint. This research represents a new approach in trying to directly identify the sedimentary mineral components that are responsible for the trace <span class="hlt">element</span> concentrations associated with the K-T boundary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988RSPTA.325..105E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988RSPTA.325..105E"><span id="translatedtitle">The Oceanic Chemistry of the Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elderfield, H.</p> <p>1988-05-01</p> <p>Because of the unique chemical characteristics of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REES), they provide information as oceanic tracers of <span class="hlt">element</span> source and reactivity. The absolute and relative concentrations of the REES in ocean waters reflect their input from rivers, by aeolian transport and from hydrothermal vents; their interaction with the bio-geochemical cycle involving removal from surface waters by adsorption and oxidation at particle surfaces (probably with organic coatings) and deeper regeneration; and the effects of advective transport. Within the REE group, Ce anomalies occur in response to oceanic redox conditions; Eu anomalies in response to aeolian and hydrothermal input; and Nd isotopic variations reflect <span class="hlt">element</span> sources. Both REE concentration patterns and Nd isotopic variations allow the effects of the vertical particle flux and of lateral advection to be separated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011NatSR...1E.145D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011NatSR...1E.145D"><span id="translatedtitle">Uncovering the Global Life Cycles of the Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Du, Xiaoyue; Graedel, T. E.</p> <p>2011-11-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are a group of fifteen <span class="hlt">elements</span> with unique properties that make them indispensable for a wide variety of emerging, critical technologies. Knowledge of the life cycles of REE remains sparse, despite the current heightened interest in their future availability. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supplies vulnerable to short and long-term disruption. To provide an improved perspective we derived the first quantitative life cycles (for the year 2007) for ten REE: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), and yttrium (Y). Of these REE, Ce and Nd in-use stocks are highest; the in-use stocks of most REE show significant accumulation in modern society. Industrial scrap recycling occurs only from magnet manufacture. We believe there is no post-customer recycling of any of these <span class="hlt">elements</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGC53C1290S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGC53C1290S"><span id="translatedtitle">Anthropogenic Disturbance of <span class="hlt">Element</span> Cycles at the <span class="hlt">Earth</span>'s Surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sen, I. S.; Peucker-Ehrenbrink, B.</p> <p>2012-12-01</p> <p>The extent to which humans are modifying <span class="hlt">Earth</span>'s surface chemistry can be quantified by comparing total anthropogenic <span class="hlt">element</span> fluxes with their natural counterparts [1]. We determine anthropogenic mass transfer of 77 <span class="hlt">elements</span> from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compared it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions and - for helium - hydrodynamic escape from the <span class="hlt">Earth</span>'s atmosphere. In addition, we introduce an approach to correct for losses during industrial processing of <span class="hlt">elements</span> belonging to geochemically coherent groups, and explicitly incorporated uncertainties of <span class="hlt">element</span> mass fluxes through Monte Carlo simulations [2]. Our assessment indicates that anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium are greater than the respective natural fluxes. For these <span class="hlt">elements</span> mining is the major factor of human dominance, whereas petroleum burning strongly influence the surficial cycle of rhenium. Apart from these 11 <span class="hlt">elements</span> there are 15 additional <span class="hlt">elements</span> whose anthropogenic fluxes may surpass their corresponding natural fluxes. Anthropogenic fluxes of the remaining <span class="hlt">elements</span> are smaller than their corresponding natural fluxes although a significant human influence is observed for all of them. For example, ~20% of the annual fluxes of C, N, and P can be attributed to human activities. Such disturbances, though small compared with natural fluxes, can significantly alter concentrations in near-surface reservoirs and affect ecosystems if they are sustained over time scales similar to or longer than the residence time of <span class="hlt">elements</span> in the respective reservoir. Examples are the continuing input of CO2 to the atmosphere that has led to a 40% increase in atmospheric CO2 concentrations, and the atmospheric redistribution of reactive nitrogen and accumulation in remote ecosystems. We note that if anthropogenic contributions to soil erosion and eolian dust are considered, anthropogenic fluxes of up to 62 <span class="hlt">elements</span> may surpass their corresponding natural fluxes. [1] Klee and Graedel (2004), Annu. Rev. Environ. Resour., 29, p. 69-107 [2] Sen and Peucker-Ehrenbrink (2012), Environ. Sci. Technol., dx.doi.org/10.1021/es301261x</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070036261','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070036261"><span id="translatedtitle">The <span class="hlt">Earth</span> Based Ground Stations <span class="hlt">Element</span> of the Lunar Program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gal-Edd, Jonathan; Fatig, Curtis; Schier, James; Lee, Charles</p> <p>2007-01-01</p> <p>The Lunar Architecture Team (LAT) is responsible for developing a concept for building and supporting a lunar outpost with several exploration capabilities such as rovers, colonization, and observatories. The lunar outpost is planned to be located at the Moon's South Pole. The LAT Communications and Navigation Team (C&N) is responsible for defining the network infrastructure to support the lunar outpost. The following <span class="hlt">elements</span> are needed to support lunar outpost activities: A Lunar surface network based on industry standard wireless 802.xx protocols, relay satellites positioned 180 degrees apart to provide South Pole coverage for the half of the lunar 28-day orbit that is obscured from <span class="hlt">Earth</span> view, <span class="hlt">earth</span>-based ground stations deployed at geographical locations 120 degrees apart. This paper will focus on the <span class="hlt">Earth</span> ground stations of the lunar architecture. Two types of ground station networks are discussed. One provides Direct to <span class="hlt">Earth</span> (DTE) support to lunar users using Kaband 23/26Giga-Hertz (GHz) communication frequencies. The second supports the Lunar Relay Satellite (LRS) that will be using Ka-band 40/37GHz (Q-band). This paper will discuss strategies to provide a robust operational network in support of various lunar missions and trades of building new antennas at non-NASA facilities, to improve coverage and provide site diversification for handling rain attenuation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26595776','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26595776"><span id="translatedtitle">Assessing rare <span class="hlt">earth</span> <span class="hlt">elements</span> in quartz rich geological samples.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Santoro, A; Thoss, V; Ribeiro Guevara, S; Urgast, D; Raab, A; Mastrolitti, S; Feldmann, J</p> <p>2016-01-01</p> <p>Sodium peroxide (Na2O2) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being (157)Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all <span class="hlt">elements</span> were achieved, generally below 10pgg(-1), as well as measurement repeatability below 15%. Overall, the Na2O2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare <span class="hlt">earth</span> <span class="hlt">element</span> content; particularly useful if checking commercial viability. PMID:26595776</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5216629','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5216629"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns in biotite, muscovite and tourmaline minerals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Laul, J.C.; Lepel, E.A.</p> <p>1986-04-21</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in the minerals biotite and muscovite from the mica schist country rocks of the Etta pegmatite and tourmalines from the Bob Ingersoll pegmatite have been measured by INAA and CNAA. The concentrations range from 10/sup -4/ g/g to 10/sup -10g//sub g/. The REE patterns of biotite, muscovite and tourmaline reported herein are highly fractionated from light to heavy REE. The REE concentrations in biotite and muscovite are high and indigenous. The pegmatite tourmalines contain low concentrations of REE. Variations in tourmaline REE patterns reflect the geochemical evolution of pegmatite melt/fluid system during crystallization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910053953&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910053953&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Compositional and phase relations among rare <span class="hlt">earth</span> <span class="hlt">element</span> minerals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burt, D. M.</p> <p>1989-01-01</p> <p>A review is presented that mainly treats minerals in which the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> are essential constituents, e.g., bastnaesite, monazite, xenotime, aeschynite, allanite. The chemical mechanisms and limits of REE substitution in some rock-forming minerals (zircon, apatite, titanite, garnet) are also derived. Vector representation of complex coupled substitutions in selected REE-bearing minerals is examined and some comments on REE-partitioning between minerals as related to acid-based tendencies and mineral stabilities are presented. As the same or analogous coupled substitutions involving the REE occur in a wide variety of mineral structures, they are discussed together.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23268141','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23268141"><span id="translatedtitle">Heavy metals, trace <span class="hlt">elements</span> and sediment <span class="hlt">geochemistry</span> at four Mediterranean fish farms.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kalantzi, I; Shimmield, T M; Pergantis, S A; Papageorgiou, N; Black, K D; Karakassis, I</p> <p>2013-02-01</p> <p>Trace <span class="hlt">element</span> concentrations in sediment were investigated at four fish farms in the Eastern Mediterranean Sea. Fish farms effects were negligible beyond 25-50 m from the edge of the cages. Based on <span class="hlt">elemental</span> distribution, sediments from the farms were separated into coarse oxidized and silty reduced ones. Fish feed is richer in P, Zn and Cd than reference and impacted stations. Comparison among impacted stations and the respective reference stations shows that, in anoxic sediments, all <span class="hlt">elements</span> had higher concentrations at the impacted stations than at reference stations while in oxic sediments, many <span class="hlt">elemental</span> concentrations were lower at impacted stations than at reference stations. The behavior of <span class="hlt">elements</span> and therefore their distribution is affected by changes in sediment grain size, organic content and redox regime. <span class="hlt">Elements</span> in sediments around fish farms can be clustered into five groups according to these environmental variables. In silty and anoxic sediments, <span class="hlt">element</span> concentrations were higher than in coarse and oxic ones. Several approaches were used to assess potential sediment toxicity (enrichment factors, geoaccumulation indices, contamination factors) as well as to assess the potential danger to aquatic life (Sediment Quality Guidelines, SQG). Cu, Zn and Fe can cause from threshold to extreme effects on aquatic life in anoxic, fine-grained sediments and As can cause threshold effects in all types of sediment around fish farms. Other <span class="hlt">elements</span> (Cr, Pb, Mn) can also cause unwanted effects when compounded with elevated background levels. PMID:23268141</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034362','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034362"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of environmentally sensitive trace <span class="hlt">elements</span> in Permian coals from the Huainan coalfield, Anhui, China</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Chen, J.; Liu, Gaisheng; Jiang, M.; Chou, C.-L.; Li, H.; Wu, B.; Zheng, Lingyun; Jiang, D.</p> <p>2011-01-01</p> <p>To study the geochemical characteristics of 11 environmentally sensitive trace <span class="hlt">elements</span> in the coals of the Permian Period from the Huainan coalfield, Anhui province, China, borehole samples of 336 coals, two partings, and four roof and floor mudstones were collected from mineable coal seams. Major <span class="hlt">elements</span> and selected trace <span class="hlt">elements</span> were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HAAS). The depositional environment, abundances, distribution, and modes of occurrence of trace <span class="hlt">elements</span> were investigated. Results show that clay and carbonate minerals are the principal inorganic constituents in the coals. A lower deltaic plain, where fluvial channel systems developed successively, was the likely depositional environment of the Permian coals in the Huainan coalfield. All major <span class="hlt">elements</span> have wider variation ranges than those of Chinese coals except for Mg and Fe. The contents of Cr, Co, Ni, and Se are higher than their averages for Chinese coals and world coals. Vertical variations of trace <span class="hlt">elements</span> in different formations are not significant except for B and Ba. Certain roof and partings are distinctly higher in trace <span class="hlt">elements</span> than underlying coal bench samples. The modes of occurrence of trace <span class="hlt">elements</span> vary in different coal seams as a result of different coal-forming environments. Vanadium, Cr, and Th are associated with aluminosilicate minerals, Ba with carbonate minerals, and Cu, Zn, As, Se, and Pb mainly with sulfide minerals. ?? 2011 Elsevier B.V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25430011','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25430011"><span id="translatedtitle">Levels of major and trace <span class="hlt">elements</span>, including rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and ²³?U in Croatian tap waters.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fiket, Željka; Rožmari?, Martina; Krmpoti?, Matea; Benedik, Ljudmila</p> <p>2015-05-01</p> <p>Concentrations of 46 <span class="hlt">elements</span>, including major, trace, and rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and (238)U in Croatian tap waters were investigated. Selected sampling locations include tap waters from various hydrogeological regions, i.e., different types of aquifers, providing insight into the range of concentrations of studied <span class="hlt">elements</span> and (238)U activity concentrations in Croatian tap waters. Obtained concentrations were compared with the Croatian maximum contaminant levels for trace <span class="hlt">elements</span> in water intended for human consumption, as well as WHO and EPA drinking water standards. Concentrations in all analyzed tap waters were found in accordance with Croatian regulations, except tap water from Šibenik in which manganese in concentration above maximum permissible concentration (MPC) was measured. Furthermore, in tap water from Osijek, levels of arsenic exceeded the WHO guidelines and EPA regulations. In general, investigated tap waters were found to vary considerably in concentrations of studied <span class="hlt">elements</span>, including (238)U activity concentrations. Causes of variability were further explored using statistical methods. Composition of studied tap waters was found to be predominately influenced by hydrogeological characteristics of the aquifer, at regional and local level, the existing redox conditions, and the household plumbing system. Rare <span class="hlt">earth</span> <span class="hlt">element</span> data, including abundances and fractionation patterns, complemented the characterization and facilitated the interpretation of factors affecting the composition of the analyzed tap waters. PMID:25430011</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3906100','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3906100"><span id="translatedtitle">Trace <span class="hlt">Elemental</span> Imaging of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Discriminates Tissues at Microscale in Flat Fossils</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B.; Cohen, Serge X.; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc</p> <p>2014-01-01</p> <p>The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting <span class="hlt">elemental</span> distributions greatly improved the discrimination of skeletal <span class="hlt">elements</span> material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline <span class="hlt">earth</span> <span class="hlt">elements</span> and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Local quantification of rare <span class="hlt">earths</span> may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies. PMID:24489809</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Litho.205..322K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Litho.205..322K"><span id="translatedtitle">Platinum-group <span class="hlt">element</span> (PGE) <span class="hlt">geochemistry</span> of Mesoarchean ultramafic-mafic cumulate rocks and chromitites from the Nuasahi Massif, Singhbhum Craton (India)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khatun, Sarifa; Mondal, Sisir K.; Zhou, Mei-Fu; Balaram, Vysetti; Prichard, Hazel M.</p> <p>2014-09-01</p> <p>The Mesoarchean Nuasahi Massif in eastern India comprises a lower ultramafic and an upper gabbro unit. The lower unit consists of orthopyroxenite, harzburgite, dunite and three chromitite bands. All of these rocks are characterized by adcumulate textures. The upper unit consists of gabbro with magnetite layers. At the contact between the eastern orthopyroxenite and the lower part of the upper gabbro, a sulfide-rich breccia zone with platinum-group-<span class="hlt">element</span> (PGE) mineralization is present. Detailed studies of major-, trace- and PGE abundances suggest that the ultramafic-mafic cumulate rocks, chromitites and breccias are genetically linked. The chondrite-normalized U-shaped rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns of the harzburgite resemble those of Phanerozoic boninite. The overall U-shaped REE patterns of the ultramafic rocks indicate derivation of the parental magma from a metasomatized depleted mantle source. The upper gabbros have higher relative abundances of trace <span class="hlt">elements</span> than the lower ultramafic rocks, due to crystallization from a fractionated magma. Whole-rock <span class="hlt">geochemistry</span> suggests that the lower ultramafic cumulate rocks with chromitites crystallized from a boninitic parental magma, whereas the upper gabbros with magnetite bands may be formed from residual boninitic magma that was contaminated by more tholeiitic-like magmas. The boninitic parental magma that crystallized to form the lower ultramafic unit was most likely generated by second-stage melting of a depleted metasomatized mantle source in a supra-subduction zone (SSZ) setting and emplaced into crustal sequences. The PGE abundances in the Nuasahi rocks provide additional constraints on their geochemical evolution during the Mesoarchean. Primitive-mantle-normalized PGE diagrams show (1) Ru enrichment in chromitites (Pd/Ru = 0.17-0.64), (2) Pd/Pt fractionation in both chromitites (Pd/Pt = 3.1) and ultramafic rocks (Pd/Pt = 0.62), (3) marked Ir depletion in ultramafic rocks (Pd/Ir = 6.3) and (4) overall PGE enrichment in chromitites (PGEtotal = 142-502 ppb). The large Ir depletion in the ultramafic rocks, and the overall Ir-depleted character of other rocks from the Nuasahi Massif, may be related to multiple episodes of melt extraction from the mantle source, giving it a subchondritic character.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.geotop.ca/upload/files/publications/chercheur/GhalebB/deves-g._chem.-geol._2012.pdf','EPRINT'); return false;" href="http://www.geotop.ca/upload/files/publications/chercheur/GhalebB/deves-g._chem.-geol._2012.pdf"><span id="translatedtitle">Research paper Chemical <span class="hlt">element</span> imaging for speleothem <span class="hlt">geochemistry</span>: Application to a</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p></p> <p></p> <p>autoradiography of radioactive <span class="hlt">elements</span> and X-ray fluorescence microspectroscopy (micro-XRF), were used to study, is probably due to a special volcanic event formed by uraniferous glass ashes easily soluble by meteoric</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24202842','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24202842"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of soils and plants in Kenyan conservation areas and implications for wildlife nutrition.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maskall, J; Thornton, I</p> <p>1991-06-01</p> <p>Trace <span class="hlt">element</span> concentrations in soils, plants and animals in National Parks and Wildlife Reserves in Kenya are assessed using geochemical mapping techniques. Soil trace <span class="hlt">element</span> concentrations are shown to be related to soil parent material and possibly to pedological and hydrological factors. At Lake Nakuru National Park, plant trace <span class="hlt">element</span> concentrations vary with plant species and the geochemical conditions that influence uptake are discussed. Impala at Lake Nakuru National Park and black rhino at Solio Wildlife Reserve are shown to have a lower blood copper status than animals from other areas. The trace <span class="hlt">element</span> status of wildlife is assessed also with respect to critical concentrations used for domestic ruminants. It is suggested that at Lake Nakuru National Park, the low soil copper content and high molybdenum content of some plants contributes to the low copper status of impala and may also influence the nutrition of other species. PMID:24202842</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4413328','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4413328"><span id="translatedtitle">Mimicking the magnetic properties of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using superatoms</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A. W.</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REs) consist of a very important group in the periodic table that is vital to many modern technologies. The mining process, however, is extremely damaging to the environment, making them low yield and very expensive. Therefore, mimicking the properties of REs in a superatom framework is especially valuable but at the same time, technically challenging and requiring advanced concepts about manipulating properties of atom/molecular complexes. Herein, by using photoelectron imaging spectroscopy, we provide original idea and direct experimental evidence that chosen boron-doped clusters could mimic the magnetic characteristics of REs. Specifically, the neutral LaB and NdB clusters are found to have similar unpaired electrons and magnetic moments as their isovalent REs (namely Nd and Eu, respectively), opening up the great possibility in accomplishing rare <span class="hlt">earth</span> mimicry. Extension of the superatom concept into the rare <span class="hlt">earth</span> group not only further shows the power and advance of this concept but also, will stimulate more efforts to explore new superatomic clusters to mimic the chemistry of these heavy atoms, which will be of great importance in designing novel building blocks in the application of cluster-assembled nanomaterials. Additionally, based on these experimental findings, a novel “magic boron” counting rule is proposed to estimate the numbers of unpaired electrons in diatomic LnB clusters. PMID:25848014</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25848014','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25848014"><span id="translatedtitle">Mimicking the magnetic properties of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using superatoms.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A W</p> <p>2015-04-21</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REs) consist of a very important group in the periodic table that is vital to many modern technologies. The mining process, however, is extremely damaging to the environment, making them low yield and very expensive. Therefore, mimicking the properties of REs in a superatom framework is especially valuable but at the same time, technically challenging and requiring advanced concepts about manipulating properties of atom/molecular complexes. Herein, by using photoelectron imaging spectroscopy, we provide original idea and direct experimental evidence that chosen boron-doped clusters could mimic the magnetic characteristics of REs. Specifically, the neutral LaB and NdB clusters are found to have similar unpaired electrons and magnetic moments as their isovalent REs (namely Nd and Eu, respectively), opening up the great possibility in accomplishing rare <span class="hlt">earth</span> mimicry. Extension of the superatom concept into the rare <span class="hlt">earth</span> group not only further shows the power and advance of this concept but also, will stimulate more efforts to explore new superatomic clusters to mimic the chemistry of these heavy atoms, which will be of great importance in designing novel building blocks in the application of cluster-assembled nanomaterials. Additionally, based on these experimental findings, a novel "magic boron" counting rule is proposed to estimate the numbers of unpaired electrons in diatomic LnB clusters. PMID:25848014</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001GeCoA..65..979R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001GeCoA..65..979R"><span id="translatedtitle">Comparative <span class="hlt">geochemistry</span> of basalts from the moon, <span class="hlt">earth</span>, HED asteroid, and Mars: implications for the origin of the moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruzicka, Alex; Snyder, Gregory A.; Taylor, Lawrence A.</p> <p>2001-03-01</p> <p>Most hypotheses for the origin of the Moon (rotational fission, co-accretion, and collisional ejection from the <span class="hlt">Earth</span>, including "giant impact") call for the formation of the Moon in a geocentric environment. However, key geochemical data for basaltic rocks from the Moon, <span class="hlt">Earth</span>, the howardite-eucrite-diogenite (HED) meteorite parent body (probably asteroid 4-Vesta), and the shergottite-nakhlite-chassignite (SNC) meteorite parent body (likely Mars), provide no evidence that the Moon was derived from the <span class="hlt">Earth</span>, and suggest that some objects with lunar-like compositions were produced without involvement of the <span class="hlt">Earth</span>. The source region compositions of basalts produced in the Moon (mare basalts) were similar to those produced in the HED asteroid (eucrites) with regard to volatile-lithophile <span class="hlt">elements</span> (Na, K, Rb, Cs, and Tl), siderophile <span class="hlt">elements</span> (Ni, Co, Ga, Ge, Re, and Ir), and ferromagnesian <span class="hlt">elements</span> (Mg, Fe, Cr, and V), and less similar to those in the <span class="hlt">Earth</span> or Mars. Mare and eucrite basalts differ in their Mn abundances, Fe/Mn values, and isotopic composition, suggesting that the Moon and HED asteroid formed in different nebular locations. However, previous claims that the Moon and HED parent body differ significantly in the abundances of some <span class="hlt">elements</span>, such as Ni, Co, Cr, and V, are not supported by the data. Instead, Cr-Mg-Fe-Ni-Co abundance systematics suggest a close similarity between the source region compositions and conditions involved in producing mare and eucrite basalts, and a significant difference from those of terrestrial basalts. The data imply that the Moon and HED asteroid experienced similar volatile-<span class="hlt">element</span> depletion and similar fractionation of metallic and mafic phases. Among hypotheses of lunar origin, rotational fission, and small-impact collisional ejection seem less tenable than co-accretion, capture, or a variant of giant-impact collisional ejection in which the Moon inherits the composition of the impactor. Both the Moon and HED asteroid may have been derived from a class of objects that were common in the early solar system. "The most plausible model for the origin of the Moon in line with geochemical and cosmochemical constraints is an impact-induced "fission" of the proto-<span class="hlt">Earth</span>." - Wänke and Dreibus (1986) "Clearly, the Moon and eucrite parent body resemble each other to a high degree. Nature produced such a composition not once but at least twice. This calls into question an entire class of models that invoke ad hoc processes to explain the Moon by a unique chance event." - Anders (1977) "The similarity between eucrites and lunar mare basalts are remarkable. Were it not for the differences in age and oxygen-isotope signature, it might be difficult to distinguish them on petrological or geochemical grounds." - Taylor (1986)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840011975','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840011975"><span id="translatedtitle">The <span class="hlt">elements</span> of the <span class="hlt">Earth</span>'s magnetism and their secular changes between 1550 and 1915</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fritsche, H.</p> <p>1983-01-01</p> <p>The results of an investigation about the magnetic agents outside the <span class="hlt">Earth</span>'s surface as well as the <span class="hlt">Earth</span>'s magnetic <span class="hlt">elements</span> for the epochs 1550, 1900, 1915 are presented. The secular changes of the <span class="hlt">Earth</span>'s magnetic <span class="hlt">elements</span> during the time interval 1550 - 1900 are also included.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.170...17B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.170...17B"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and neodymium isotopes in world river sediments revisited</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bayon, G.; Toucanne, S.; Skonieczny, C.; André, L.; Bermell, S.; Cheron, S.; Dennielou, B.; Etoubleau, J.; Freslon, N.; Gauchery, T.; Germain, Y.; Jorry, S. J.; Ménot, G.; Monin, L.; Ponzevera, E.; Rouget, M.-L.; Tachikawa, K.; Barrat, J. A.</p> <p>2015-12-01</p> <p>Over the past decades, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) and their radioactive isotopes have received tremendous attention in sedimentary <span class="hlt">geochemistry</span>, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on <span class="hlt">elemental</span> concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world's major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during <span class="hlt">Earth</span> surface processes. Our results confirmed earlier assumptions that river sediments do not generally exhibit any significant grain-size dependent Nd isotopic variability. Most sediments from rivers draining old cratonic areas, sedimentary systems and volcanic provinces displayed similar Nd isotopic signatures in both clay and silt fractions, with ??Nd(clay-silt) < |1|. A subtle decoupling of Nd isotopes between clays and silts was identified however in a few major river systems (e.g. Nile, Mississippi, Fraser), with clays being systematically shifted towards more radiogenic values. This observation suggests that preferential weathering of volcanic and/or sedimentary rocks relative to more resistant lithologies may occur in river basins, possibly leading locally to Nd isotopic decoupling between different size fractions. Except for volcanogenic sediments, silt fractions generally displayed homogeneous REE concentrations, exhibiting relatively flat shale-normalized patterns. However, clay fractions were almost systematically characterized by a progressive enrichment from the heavy to the light REE and a positive europium (Eu) anomaly. In agreement with results from previous soil investigations, the observed REE fractionation between clays and silts is probably best explained by preferential alteration of feldspars and/or accessory mineral phases. Importantly, this finding clearly indicates that silicate weathering can lead to decoupling of REE between different grain-size fractions, with implications for sediment provenance studies. Finally, we propose a set of values for a World River Average Clay (WRAC) and Average Silt (WRAS), which provide new estimates for the average composition of the weathered and eroded upper continental crust, respectively, and could be used for future comparison purposes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850007334&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850007334&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth"><span id="translatedtitle">The chemistry of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the solar nebula</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Larimer, J. W.; Bartholomay, H. A.; Fegley, B.</p> <p>1984-01-01</p> <p>The high concentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in primitive CaS suggests that the REE along with the other normally lithophile <span class="hlt">elements</span> form stable sulfides under the unusual conditions which existed during the formation of enstatite chrondites. In order to acquire a more quantitative framework in which to interpret these data, the behavior of the REE in systems with solar, or slightly fractionated solar, composition is being studied. These new data introduce modest changes in the behavior of some of the REE when compared to previous studies. For example, the largest differences are in the stabilities of the gaseous monoxides of Ce, Eu, Tb, Ho, and Tm, all of which now appear to be less stable than previously thought, and YbO(g) which is somewhat more stable. Much more significant are the changes in REE distribution in the gas phase in fractionated systems, especially those made more reducing by changing the C/O ratio from the solar value of 0.6 to about 1.0. In almost all cases, the exceptions being Eu, Tm and Yb whose <span class="hlt">elemental</span> gaseous species dominate, the monosulfides become more abundant. Moreover, the solid oxides of Eu, Tm and Yb become less stable under more reducing conditions which, in effect, should reduce the condensation temperature of all REE in more reduced systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988E%26PSL..87..409C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988E%26PSL..87..409C"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> <span class="hlt">geochemistry</span> of an anorthosite-diorite suite, Namaqua mobile belt, South Africa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conradie, J. A.; Schoch, A. E.</p> <p>1988-03-01</p> <p>A swarm of small dyke-like plutons, ranging in composition from anorthosite through diorite and norite, to hypersthenite and glimmerite, occurs in the western part of the Namaqua mobile belt, South Africa. Known as the Koperberg Suite, these rocks host important magmatic sulphide deposits. Zircon ages of approximately 1100 Ma suggest that the suite was emplaced after the peak of the regional high-grade metamorphism, dated at 1200 Ma. A postulated comagmatic origin for the various rock types is confirmed by the REE distributions of anorthosite, leucodiorite, diorite, hypersthenite and glimmerite. The Koperberg Suite resembles the well-known massif anorthosite complexes, typified by the Adirondack Suite, in most properties except for the dispersed mode of occurrence. It is now shown that the similarity also holds for the REE spectra. Thus, the predominant anorthosite and leucodiorite of the Koperberg Suite are comparable to similar rocks of the Adirondacks and the Burwash area, Ontario, albeit more enriched in LREE. More mafic rock types such as norite, mica-diorite and glimmerite are substantially enriched in LREE compared to mafic differentiates of massif anorthosites. Apatite is abundant in the mafic rocks and stores large proportions of the lanthanides. The occurrence of apatite- and mica-rich assemblages indicates source magmas enriched in K, REE and P. A few intrusives exhibit excessively enriched REE patterns which are attributed to late hydrothermal alteration or metasomatism. The REE data for syenite and two-pyroxene assemblages from the Copper District argue against a genetic relationship to the Koperberg Suite in spite of close spatial association.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4156694','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4156694"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> activate endocytosis in plant cells</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Lihong; Li, Jigang; Zhou, Qing; Yang, Guangmei; Ding, Xiao Lan; Li, Xiaodong; Cai, Chen Xin; Zhang, Zhao; Wei, Hai Yan; Lu, Tian Hong; Deng, Xing Wang; Huang, Xiao Hua</p> <p>2014-01-01</p> <p>It has long been observed that rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) regulate multiple facets of plant growth and development. However, the underlying mechanisms remain largely unclear. Here, using electron microscopic autoradiography, we show the life cycle of a light REE (lanthanum) and a heavy REE (terbium) in horseradish leaf cells. Our data indicate that REEs were first anchored on the plasma membrane in the form of nanoscale particles, and then entered the cells by endocytosis. Consistently, REEs activated endocytosis in plant cells, which may be the cellular basis of REE actions in plants. Moreover, we discovered that a portion of REEs was successively released into the cytoplasm, self-assembled to form nanoscale clusters, and finally deposited in horseradish leaf cells. Taken together, our data reveal the life cycle of REEs and their cellular behaviors in plant cells, which shed light on the cellular mechanisms of REE actions in living organisms. PMID:25114214</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016379&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016379&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">elements</span> in individual minerals in Shergottites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wadhwa, Meenakshi; Crozaz, Ghislaine</p> <p>1993-01-01</p> <p>Shergottites (i.e., Shergotty, Zagami, EETA79001, ALHA77005, and LEW88516) are an important set of achondrites because they comprise the majority of the SNC group of meteorites (nine, in total, known to us), which are likely to be samples of the planet Mars. Study of these meteorites may therefore provide valuable information about petrogenetic processes on a large planetary body other than <span class="hlt">Earth</span>. Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) distributions between various mineral phases were found to be useful in geochemically modeling the petrogenesis of various rock types (terrestrial and meteoritic). However, with the exception of a few ion microprobe studies and analyses of mineral separates, there has previously not been any comprehensive effort to characterize and directly compare REE in individual minerals in each of the five known shergottites. Ion microprobe analyses were made on thin sections of each of the shergottites. Minerals analyzed were pyroxenes (pigeonite and augite), maskelynite, and whitlockite. The REE concentrations in each mineral type in each shergottite is given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Natur.523..293T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Natur.523..293T"><span id="translatedtitle"><span class="hlt">Earth</span> science: Big <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Till, Christy</p> <p>2015-07-01</p> <p>A compilation of more than 300,000 rock compositions provides crucial input into a 100-year-old debate on how the continental crust formed, and provides new constraints for theories of continental-crust development. See Article p.301</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CorRe..31..671M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CorRe..31..671M"><span id="translatedtitle">Potassium and other minor <span class="hlt">elements</span> in Porites corals: implications for skeletal <span class="hlt">geochemistry</span> and paleoenvironmental reconstruction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitsuguchi, T.; Kawakami, T.</p> <p>2012-09-01</p> <p>We investigated how the K/Ca, Na/Ca, Mg/Ca, and Sr/Ca ratios of powders ground from Porites coral skeletons are changed by cumulative chemical treatments to the powders: first with distilled/deionized water (DDW), next with 30 % H2O2 and then with 0.004 mol l-1 HNO3. The K/Ca, Na/Ca, and Mg/Ca ratios were decreased with the DDW treatment and then increased with the H2O2 and HNO3 treatments; the Sr/Ca ratio was slightly decreased through the cumulative treatments, suggesting fine-scale (tens of ?m or less) <span class="hlt">elemental</span> heterogeneities in the skeleton—K, Na, and Mg are significantly enriched at the skeletal surface and also at the center of calcification (COC); in contrast, the heterogeneity of Sr is very small. We suggest that the principal mechanisms of K incorporation into coral skeleton are (1) ion incorporation into lattice defects/distortions and (2) ion adsorption onto crystal discontinuities (including crystal-organic matter interfaces) as forms of K+ and KSO4 -. Furthermore, we measured the <span class="hlt">element</span>/Ca ratios of a modern Porites coral skeleton along its growth direction at 2-mm intervals. Results showed that all the <span class="hlt">element</span>/Ca ratios displayed annual cycles, that the K/Ca and Na/Ca ratios covaried with each other, and that the annual-minimum K/Ca and Na/Ca ratios coincided with the annual high-density band in the skeleton. It is unclear what environmental factors may cause the covarying annual cycles of the K/Ca and Na/Ca ratios; however, as a possible explanation, the cycles may be due not to environmental factors, but to a combined effect of (1) the K and Na enrichment at the COC, (2) annual bands of high- and low-density skeleton, and (3) mm-scale <span class="hlt">element</span>/Ca measurements along the skeletal growth direction. This kind of effect on geochemical proxies of which the concentrations significantly differ between the COC and surrounding skeleton may generate false or distorted paleoenvironmental signals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21176850','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21176850"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of Jurassic coals from Eastern Black Sea Region, NE-Turkey</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cebi, F.H.; Korkmaz, S.; Akcay, M.</p> <p>2009-07-01</p> <p>The majority of coal deposits in the world are of Carboniferous and Tertiary age but Jurassic coals are seldom present. They are also exposed in northern Turkey and occur both at the lower and upper sections of the Liassic-Dogger volcanic- and volcani-clastic series. The coals at the base of the Jurassic units are characterized by higher Ba, Th, Zr, and Cr-Ni and lower S values than those at the top of the units, indicating, in general, laterally consistent trace <span class="hlt">element</span> contents. The vertical distribution of trace <span class="hlt">elements</span> in individual coal seams is also rather consistent. The B contents of coals from the Godul and Norsun areas vary from 1.5 to 4.3 ppm whereas those from the Alansa area are in the range of 95 to 138 ppm. This suggests that the coals in the Godul and Norsun areas were deposited in a swamp environment inundated by the sea from time to time, whereas coals of the Alansa were deposited in a saline environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5224579','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5224579"><span id="translatedtitle">Stratigraphy and major <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Lassen Volcanic Center, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clynne, M.A.</p> <p>1984-01-01</p> <p>Detailed geologic mapping of 200 km/sup 2/ in and near Lassen Volcanic National Park, California and reconnaissance of the surrounding area, combined with reinterpretation of data in the literature, allow definition of the Lassen Volcano Center and provide the stratigraphic framework necessary for interpretation of major-<span class="hlt">element</span> chemical data. The Lassen Volcanic Center developed in three stages. Stage I and II produced Brokeoff Volcanic, an andesitic composite cone that erupted mafic andesite to dacite 0.6 to 0.35 my ago. Volcanism then shifted in character and locale. Domes and flows of dacite and rhyodacite, and flows of hybrid andesite were erupted on the northern flank of Brokeoff Volcano during the period from 0.25 my ago to the present; these rocks comprise Stage III of the Lassen Volcanic Center. Rocks of the Lassen Volcanic Center are typical of subduction-related calc-alkaline volcanic rocks emplaced on a continental margin overlying sialic crust. Porphyritic andestic and dacite with high Al/sub 2/O/sub 3/, low TiO/sub 2/, medium K/sub 2/O, and FeO/MgO 1.5-2.0 are the most abundant rock types. Major-<span class="hlt">element</span> chemical trends of rock sequences indicate a mafic to silicic evolution for magmas of the Lassen Volcanic Center, probably owing to crystal fractionation of calc-alkaline basalt. 23 figs., 5 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JVGR...85..405B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JVGR...85..405B"><span id="translatedtitle">Major-<span class="hlt">element</span>, trace-<span class="hlt">element</span>, and Sr Nd isotopic <span class="hlt">geochemistry</span> and genesis of Varto (Mu?) volcanic rocks, Eastern Turkey</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buket, Ersen; Temel, Abidin</p> <p>1998-10-01</p> <p>Major-<span class="hlt">element</span>, trace-<span class="hlt">element</span> and Sr-Nd isotopic data are presented for the Upper Miocene-Quaternary Varto volcanic rocks (Eastern Turkey) and their relationship to the regional tectonic regime were investigated in this study. The Varto volcanic rocks are located in the eastern part of the North Anatolian Fault Zone (NAFZ), in the East Anatolian Convergence Region (EACR). Volcanic rocks are subdivided into two groups: Lower Volcanic Units (LVU) and Upper Volcanic Units (UVU). These volcanic rocks are composed of volcaniclastics and lavas of both alkaline and calc-alkaline characters. LVU lavas are dacite, andesite, trachyte, basaltic andesite, benmoreite, and mugearite, whereas UVU lavas are basalt, basaltic andesite, mugearite, hawaite, benmoreite, and basanite in composition. Variation diagrams of SiO 2 with major- and trace-<span class="hlt">elements</span> are consistent with fractional crystallization process involving olivine, plagioclase, pyroxenes, and Fe-Ti oxides. Both units appear to be on the same fractionation trend, implying similar origins, but different degrees of evolution. Correlation between Sr-Nd isotopes with SiO 2, MgO, Rb/Sr, 100/Sr, and Nd/Sm emphasize the effect of crustal contamination on these volcanic rocks. Sr-Nd isotopic data plot along the mantle array. However, rocks of Lower and Upper Volcanic Units are isotopically distinct. UVU have relatively low 87Sr/ 86Sr (0.70334-0.70466) and high 143Nd/ 144Nd ratios (0.51279-0.51288), which plot in the field of Oceanic Island basalts, Ararat lavas and the Eastern Anatolian alkaline province; in contrast, LVU exhibit higher 87Sr/ 86Sr (0.70438-0.70507) and lower 143Nd/ 144Nd (0.51265-0.51276) ratios. All the Varto volcanic rocks are products of mantle-derived magma and have experienced assimilation and fractional crystallization (AFC) during uprise through the continental crust, and formed in a within-plate environment along the Eastern part of the NAFZ that is closely related to deep lithospheric fractures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...814...78R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...814...78R"><span id="translatedtitle">Evaluating Changes In the <span class="hlt">Elemental</span> Composition of Micrometeorites During Entry into the <span class="hlt">Earth’s</span> Atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rudraswami, N. G.; Shyam Prasad, M.; Dey, S.; Plane, J. M. C.; Feng, W.; Taylor, S.</p> <p>2015-11-01</p> <p>We evaluate the heating of extraterrestrial particles entering the atmosphere using the comprehensive chemical ablation model (CABMOD). This model predicts the ablation rates of individual <span class="hlt">elements</span> in a particle with a defined size, composition, entry velocity, and entry angle with respect to the zenith (ZA). In the present study, bulk chemical analyses of 1133 Antarctica micrometeorites (collected from the south pole water well) are interpreted using CABMOD. The marked spread in Fe/Si values in unmelted, partially melted, and melted micrometeorites is explained by the loss of relatively volatile Fe during atmospheric entry. The combined theoretical modeling and <span class="hlt">elemental</span> composition of the micrometeorites (Mg/Si ratios) suggest that ?85% of particles have a provenance of carbonaceous chondrites, the remaining ?15% are either ordinary or enstatite chondrites. About 65% of the micrometeorites have undergone <20% ablation, while a further 20% have lost between 20% and 60% of their original mass. This has implications for understanding the micrometeorite flux that reaches the <span class="hlt">Earth</span>'s surface, as well as estimating the pre-atmospheric size of the particles. Our work shows that the unmelted particles that contribute ?50% to the total micrometeorite collection on <span class="hlt">Earth</span>'s surface have a small entry zone: ZA = 60°–90° if the entry velocity is ?11 km s?1, and ZA = 80°–90° for >11–21 km s?1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/ofr20071047SRP078','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/ofr20071047SRP078"><span id="translatedtitle">Major, trace <span class="hlt">element</span> and stable isotope <span class="hlt">geochemistry</span> of synorogenic breccia bodies, Ellsworth Mountains, Antarctica</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Craddock, J.P.; McGillion, M.S.; Webers, G.F.</p> <p>2007-01-01</p> <p>Cambrian carbonates in the Heritage Range of the Ellsworth Mountains, West Antarctica host a series of carbonate-rich breccia bodies that formed contemporaneously with the Permian Gondwanide orogen. The breccia bodies had a three-stage genesis, with the older breccias containing Cambrian limestone (and marble) clasts supported by calcite, whereas the younger breccias are nearly clast-free and composed entirely of matrix calcite. Breccia clasts, calcite matrix and detrital matrix samples were analyzed using x-ray fluorescence (major and trace <span class="hlt">elements</span>), x-ray diffraction, and stable isotopes (C, O) and suggest that the breccias formed as part of a closed geochemical system, at considerable depth, within the Cambrian limestone host as the Ellsworth Mountains deformed into a fold-and-thrust belt along the margin of Gondwana</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014569','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014569"><span id="translatedtitle">Platinum-group <span class="hlt">element</span> <span class="hlt">geochemistry</span> of zoned ultramafic intrusive suites, Klamath Mountains, California and Oregon.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Gray, F.; Page, N.J.; Carlson, C.A.; Wilson, S.A.; Carlson, R.R.</p> <p>1986-01-01</p> <p>Analyses for platinum-group <span class="hlt">elements</span> of the varied rock suites of three Alaskan-type ultramafic to mafic multi-intrusive bodies are reported. Ir and Ru are less than analytical sensitivities of 100 and 20 ppb; Rh is less than or near 1 ppb. Average Pd assays vary among the rocks within intrusive complexes and between the three complexes (6.3, 13.7, 36.4 ppb); average Pt assays vary little among the same samples (27.9, 60.9, 34.0 ppb). Statistically adjusted Pt/(Pt + Pd) ratios increase in each suite from gabbro through clinopyroxenite to olivine-rich rocks, possibly owing to Pd fractionation.-G.J.N.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013127','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013127"><span id="translatedtitle">Characterization of the Sukinda and Nausahi ultramafic complexes, Orissa, India by platinum-group <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Page, N.J.; Banerji, P.K.; Haffty, J.</p> <p>1985-01-01</p> <p>Samples of 20 chromitite, 14 ultramafic and mafic rock, and 9 laterite and soil samples from the Precambrian Sukinda and Nausahi ultramafic complexes, Orissa, India were analyzed for platinum-group <span class="hlt">elements</span> (PGE). The maximum concentrations are: palladium, 13 parts per billion (ppb); platinum, 120 ppb; rhodium, 21 ppb; iridium, 210 ppb; and ruthenium, 630 ppb. Comparison of chondrite-normalized ratios of PGE for the chromitite samples of lower Proterozoic to Archean age with similar data from Paleozoic and Mesozoic ophiolite complexes strongly implies that these complexes represent Precambrian analogs of ophiolite complexes. This finding is consistent with the geology and petrology of the Indian complexes and suggests that plate-tectonic and ocean basin developement models probably apply to some parts of Precambrian shield areas. ?? 1985.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAfES.100..335M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES.100..335M"><span id="translatedtitle">Redox control on trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and provenance of groundwater in fractured basement of Blantyre, Malawi</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mapoma, Harold Wilson Tumwitike; Xie, Xianjun; Zhang, Liping</p> <p>2014-12-01</p> <p>Assessment of redox state, pH, environmental isotope ratios (?18O, ?2H) coupled with PHREEQC speciation modeling investigations were conducted to understand trace <span class="hlt">element</span> geochemical controls in basement complex aquifer in Blantyre, Malawi. Groundwater in the area is typical Ca-Mg-Na-HCO3 type suggesting more of carbonate weathering and significance of carbon dioxide with dissolution of evaporites, silicate weathering and cation exchange being part of the processes contributing to groundwater mineralization. The significance of pH and redox status of groundwater was observed. The groundwater redox state was mostly O2-controlled with few exceptions where mixed (oxic-anoxic) O2-Mn(IV) and O2-Fe(III)/SO4 controlled redox states were modeled. More so, some of the main trace <span class="hlt">element</span> species modeled with PHREEQC varied with respect to pH. For instance vanadium(III) and vanadium(IV) decreased with increase in field pH contrasting the trend observed for vanadium(V). The isotopic composition of the sampled groundwater varied between -5.89‰ and -3.32‰ for ?18O and -36.98‰ and -20.42‰ for ?2H. The ?2H/?18O and ?18O/Cl- ratios revealed that groundwater is of meteoric origin through vertical recharge and mixing processes. The d-excess value approximated the y-intercept of GMWL of 10 (d-excess = 9.269, SD = 1.240) implying that influence of secondary evaporative processes on isotopic signature of the study area is minimal. Thus, there is evidence to suggest that groundwater chemistry in the studied aquifer is influenced by inherent processes with contribution from human activities and furthermore, the water originates from rainwater recharge. With such results, more studies are recommended to further constrain the processes involved in mineralization through isotopic fractionation investigations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H34C..01M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H34C..01M"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> analysis indicates micropollutants in an urban estuary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohajerin, T. J.; Johannesson, K. H.; Kolker, A.; Burdige, D. J.; Chevis, D.</p> <p>2011-12-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> analysis of Bayou Bienvenue waters shows anomalously high gadolinium, Gd, concentrations relative to its nearest neighbors in the REE series, europium and terbium. The anomalously high Gd concentrations indicate anthropogenic input from waste-water treatment plants in the area as anthropogenic Gd input can be traced back to its use as a contrast agent in magnetic resonance imaging in hospitals. Others have shown that anomalously high levels of Gd in natural waters are likely to be associated with other micropollutants that also occur in hospital effluent and that are not removed in the wastewater treatment process, including pharmaceuticals in the form of steroids, antihistamines, and antibiotics. Estuaries serve as many important ecological roles and have been shown to act as a filter for pollutants. To better understand the transport, biogeochemical cycling, and ultimate fate of trace <span class="hlt">elements</span> in estuaries, I collected surface water samples from Bayou Bienvenue, a wetland triangle that covers an area of 427 acres directly adjacent to New Orleans, Louisiana. Water samples from Bayou Bienvenue were collected along the salinity gradient and subsequently filtered through progressively smaller pore-size filters. The resulting fractions were analyzed for trace <span class="hlt">element</span> concentions, including the REEs, by magnetic sector ICP-MS. The attached figure shows the Gd anomaly present in the particulate (>0.45?m) fraction. Upper continental crust (UCC)-normalized plots of colloidal REEs (0.02?m - 0.45?m) fraction is lacking this anomaly indicating anthropogenic Gd is found chiefly in the particulate fraction in Bayou Bienvenue. No clear relationship between Gd concentration and salinity was apparent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070010740','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070010740"><span id="translatedtitle">Crystal Field Effects and Siderophile <span class="hlt">Element</span> Partitioning: Implications for Mars HSE <span class="hlt">Geochemistry</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, John H.; Malavergne, V.; Neal, C. R.</p> <p>2007-01-01</p> <p>Analyses of martian (SNC) meteorites indicate that Pt abundances do not vary much compared to other highly siderophile <span class="hlt">elements</span> (HSE). Therefore, Jones et al. [1] inferred that D(Pt) during basalt petrogenesis was of order unity. This inference was at odds with previously published experiments that gave a D(sub ol/liq) for Pt of approx. 0.01 [2]. Because olivine is likely to be an important constituent of any reasonable martian mantle, the implication of these findings is that minor minerals must have D(Pt) much greater than 1, which seemed improbable. However, not only did the SNC evidence point to a D(sub ol/liq) approx. equal to 1, but so did plots of D(sub ol/liq) vs. ionic radius (Onuma diagram). The ionic radius of Pt(2+) suggested that D(sub ol/liq) for Pt was of order unity, in agreement with the inferences from SNC meteorites. New experiments have failed to detect measurable Pt in olivine, even at high oxygen fugacities [3]. Therefore, some other parameter, other than ionic charge and radius, must hold sway during olivine liquid partitioning of Pt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050210032','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050210032"><span id="translatedtitle">Microbial Paleontology, Mineralogy and <span class="hlt">Geochemistry</span> of Modern and Ancient Thermal Spring Deposits and Their Recognition on the Early <span class="hlt">Earth</span> and Mars"</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Farmer, Jack D.</p> <p>2004-01-01</p> <p>The vision of this project was to improve our understanding of the processes by which microbiological information is captured and preserved in rapidly mineralizing sedimentary environments. Specifically, the research focused on the ways in which microbial mats and biofilms influence the sedimentology, <span class="hlt">geochemistry</span> and paleontology of modem hydrothermal spring deposits in Yellowstone national Park and their ancient analogs. Toward that goal, we sought to understand how the preservation of fossil biosignatures is affected by 1) taphonomy- the natural degradation processes that affect an organism from the time of its death, until its discovery as a fossil and 2) diagenesis- longer-term, post-depositional processes, including cementation and matrix recrystallization, which collectively affect the mineral matrix that contains fossil biosignature information. Early objectives of this project included the development of observational frameworks (facies models) and methods (highly-integrated, interdisciplinary approaches) that could be used to explore for hydrothermal deposits in ancient terranes on <span class="hlt">Earth</span>, and eventually on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.5062H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.5062H"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of arsenic and other trace <span class="hlt">elements</span> in a volcanic aquifer system of Kumamoto Area, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hossain, Shahadat; Hosono, Takahiro; Shimada, Jun</p> <p>2015-04-01</p> <p>Total arsenic (As), As(III) species, dissolved organic carbon (DOC), methane (CH4), sulfur isotope ratios of sulfate (?34SSO4), major ions and trace <span class="hlt">elements</span> were measured in groundwater collected from boreholes and wells along the flow lines of western margins of Kumamoto basin, at central part of Kyushu island in southern Japan. Kumamoto city is considered as the largest groundwater city in Japan. 100% people of this city depends on groundwater for their drinking purpose. In this study, we used trace <span class="hlt">elements</span> data and ?34SSO4 values to better understand the processes that are likely controlling mobilization of As in this area. Arsenic concentrations ranges from 1 to 60.6 ?g/L. High concentrations were found in both shallow and deep aquifers. The aquifers are composed of Quaternary volcanic (pyroclastic) flow deposits. In both aquifers, groundwaters evolve along the down flow gradient from oxidizing conditions of recharge area to the reducing conditions of stagnant area of Kumamoto plain. 40% samples from the Kumamoto plain area excced the maximum permissible limit of Japan drinking water quality standard (10 ?g/L). In the reducing groundwater, As(III) constitutes typically more, however; 50% samples dominated with As(III) and 50% samples dominated with As(V) species. High As concentrations occur in anaerobic stagnant groundwaters from this plain area with high dissolved Fe, Mn, moderately dissolved HCO3, PO4, DOC and with very low concentrations of NO3 and SO4 suggesting the reducing condition of subsurface aquifer. Moderately positive correlation between As and dissolved Fe, Mn and strong negative correlation between As(III)/As(V) ratio and V, Cr and U reflect the dependence of As concentration on the reductive process. The wide range of ?34SSO4 values (6.8 to 36.1‰) indicate that sulfur is undergoing redox cycling. Highly enriched values suggesting the process was probably mediated by microbial activity. It also be noted from positive values of sulfur isotopes that sulfate was not originated from oxidation process of pyrite. A weak correlation was observed between ?34SSO4 values and total As contents when all the samples were considered. Although, there is evidence for sulfate reduction, however; it is less clear about co-pricipitation or sequester of As with Fe and Sulfide ion. It is evident that As distribution in subsurface geological media is not controlled by single solid phase. Probably, dissolution-desorption from different phases contributes to the total As in groundwater. The data are consistant with the possibility that microbial mediated reactions and reductive dessolution of Fe-oxyhydroxides are the important processes to mobilize arsenic in this area. The combination of slow flow of groundwater and the younger age of aquifer sediments are also considered potentially important causes for the high dissolved As concentrations in groundwater as the sediments have not been well flushed since burial.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7084C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7084C"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> exploitation, geopolitical implications and raw materials trading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chemin, Marie-Charlotte</p> <p>2015-04-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) correspond to seventeen <span class="hlt">elements</span> of the periodic table. They are used in high technology, cracking, electric cars' magnet, metal alloy for batteries, and also in phone construction or ceramics for electronic card. REEs are an important resource for high technology. This project targets 16 years old students in the subject "personalized aid" and will last six weeks. The purpose of this project is to develop autonomy and research in groups for a transdisciplinary work. This project gathers knowledge in geology, geography and economics. During the first session students analyze the geology applications of the REE. They begin the analysis with learning the composition in different rocks such as basalt and diorite to make the link with crystallization. Then they compare it with adakite to understand the formation of these rocks. In the second session, they study REE exploitation. We can find them as oxides in many deposits. The principal concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> are associated with uncommon varieties of igneous rocks, such as carbonatites. They can use Qgis, to localize this high concentration. In the third session, they study the environmental costs of REE exploitation. Indeed, the exploitation produces thorium and carcinogenic toxins: sulphates, ammonia and hydrochloric acid. Processing one ton of rare <span class="hlt">earths</span> produces 2,000 tons of toxic waste. This session focuses, first, on Baotou's region, and then on an example they are free to choose. In the fourth session, they study the geopolitical issues of REE with a focus on China. In fact this country is the largest producer of REE, and is providing 95% of the overall production. REE in China are at the center of a geopolitical strategy. In fact, China implements a sort of protectionism. Indeed, the export tax on REE is very high so, as a foreign company, it is financially attractive to establish a manufacturing subsidiary in China in order to use REE. As a matter of fact, establishing a company in China can lower the production cost (since the company buys the products used in its production at a lower price). In the fifth session, they study the raw materials trading based on the futures contracts example. A producer, to avoid a rise in prices of raw materials used in his production can use derivative products on the financial market: futures contracts for instance. This product ensures a quantity and quality for a price and a delivery date agreed upon today. Actually, producers can use a method called Fix price hedging in order to fix the price of a specific product. The main idea is to balance out the "physical position" (spot market) and the "paper position" (futures market). Even if the REE are commercialized in form of a non-perishable's oxide, the flow of the stock must be guaranteed and this is why it is important for producers to secure their supply of raw materials. In the last session, students search local companies that use REE in their production process and study their strategy on the market.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5328M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5328M"><span id="translatedtitle">Geochemical behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and other trace <span class="hlt">elements</span> in the Amazon River</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merschel, Gila; Bau, Michael; Dantas, Elton Luiz</p> <p>2014-05-01</p> <p>Rivers transport large amounts of dissolved and suspended particulate material from the catchment area to the oceans and are a major source of trace metals to seawater. The Amazon River is the world's largest river and supplies approximately 20% of the oceans' freshwater (Molinier et al., 1997). However, the behavior of trace <span class="hlt">elements</span>, especially particle-reactive <span class="hlt">elements</span> such as the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE), within the river as well as in the estuary is not well constrained and rather little is known about their transport mechanisms. This study aims at understanding the transport properties of particle-reactive <span class="hlt">elements</span> in the Amazon River and some of its major tributaries, including the Rio Solimões, Rio Negro, Tapajos, Xingu and Jari Rivers. Samples were taken at 12 stations, seven of which were located in the Amazon mainstream, while the other five stations sampled its tributaries. To account for the effects of variable discharge, the samples were collected during periods of high and low discharge. We present data for major and trace <span class="hlt">elements</span>, including REE, of the dissolved and suspended load of these samples. First results indicate that the shale-normalized REE pattern of the dissolved load (filtered through 0.2 µm membranes) of the Amazon mainstream and the Rio Solimões confirm earlier studies (Elderfield et al., 1990; Gerard et al., 2003) and show an enrichment of the middle REE relative to the light and heavy REE (LaSN/GdSN: 0.25 - 0.32; GdSN/YbSN: 1.54 - 1.78). In contrast to the Amazon mainstream and the Rio Solimões, which are considered to be whitewater rivers, blackwater rivers, such as the Rio Negro, have a flat REE pattern with higher REE concentrations than whitewater rivers. The third water-type found in the Amazon Basin is clearwater, e.g. Rio Tapajos, with REE patterns in between those of the other two types, i.e. LaSN/GdSN: 0.55 - 0.70; GdSN/YbSN: 1.26 - 1.55. A similar behavior can be identified for other major and trace <span class="hlt">elements</span>. While <span class="hlt">elements</span> such as Ca, Mg, Sr or U are relatively high in whitewater rivers, their concentrations are generally lower in clearwater rivers and lowest in blackwater rivers. In contrast, <span class="hlt">elements</span> including Si, Rb and Cs have their highest concentrations in blackwater rivers, intermediate concentrations in clearwater rivers and their lowest concentrations in whitewater river. [1] Elderfield H., Upstill-Goddard R. and Sholkovitz E.R. (1990): The rare <span class="hlt">earth</span> <span class="hlt">elements</span> in rivers, estuaries and coastal seas and their significance to the composition of ocean waters. Geochim.Cosmochim.Acta, 54, 971-991 [2] Gerard M., Seyler P., Benedetti M.F., Alves V.P., Boaventura G.R. and Sondag, F. (2003): Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Amazon basin. Hydrological Processes, 17, 1379-1392 [3] Molinier M., Guyot J.L., Callede J., Guimaraes V., Oliveira E. and Filizola N. (1997): Hydrologie du bassinamazonien. Evironment et développement en Amazonie brésiliènne, Thery H. (ed.), Berlin Publ., Paris; 24-41</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.8541B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.8541B"><span id="translatedtitle">Targeting heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> in carbonatite complexes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Broom-Fendley, S.; Wall, F.; Gunn, A. G.; Dowman, E.</p> <p>2012-04-01</p> <p>The world's main sources of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are concentrated in carbonatite complexes. These have the advantages of high grade and tonnage, combined with low thorium contents, yet they are generally enriched in light rare <span class="hlt">earths</span> (LREE). The heavy rare <span class="hlt">earths</span> (HREE, which include Eu-Lu and Y) are more highly sought after because of their role in new and green technologies. HREE are predominantly extracted from ion-adsorption clays in China. These are small, low grade deposits, which are often illegally mined by artisans. Increased government control, environmental legislation and local demand for REE in China have led to high prices and global concerns about the security of supply of the HREE. Alternative sources of the HREE are poorly documented. We present a review of such targets, including: (1) 'abnormal' carbonatites; (2) areas around LREE-rich complexes such as breccia, fenite and latter stage veins; and (3) weathered carbonatites. At Lofdal, Namibia, carbonatite dykes contain xenotime-(Y) together with LREE minerals. The original chemistry of the carbonatite magma, coupled with late-stage magma and fluid evolution, seem to be controlling factors [1, 2]. The Khibina carbonatite, Kola Peninsula, Russia, is an example of where early LREE carbonatites become increasing HREE-enriched as magmas evolve to carbo-hydrothermal fluids [3]. Around carbonatite complexes in Malawi HREE enrichment can be found in breccia and in fenite. Breccia around Songwe shows areas with high Y/La ratios within the matrix caused by narrow zones of xenotime enrichment. Fenite around Kangankunde and Chilwa Island has higher HREE:LREE ratios than the carbonatite [4]. At weathered complexes, such as at Mount Weld in Western Australia, changes in both HREE concentration and LREE:HREE ratios are observed. In currently unworked sections of the deposit, the HREE mineral churchite (YPO4.H2O) has formed concentrations due to groundwater flow [5]. These areas of enrichment are reviewed in terms of their grade, tonnage, rock type and the potential environmental impacts associated with their exploitation. [1] Wall et al. (2008), Can Mineral, 46, 861. [2] Do Cabo et al. (2011), Minmag, 75 (3), 770. [3] Zaitsev et al. (1998), Minmag, 62 (2), 225. [4] Dowman et al. (2011), abstract, Fermor conference, London. [5] Lottermoser (1990), Lithos, 24, 151</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.B21C0371R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.B21C0371R"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in scleractinian cold-water corals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raddatz, J.; Liebetrau, V.; Hathorne, E. C.; Rüggeberg, A.; Dullo, W.; Frank, M.</p> <p>2012-12-01</p> <p>The Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) have a great potential to trace continental input, particle scavenging and the oxidation state of seawater. These REE are recorded in the skeleton of the cosmopolitan cold-water corals Lophelia pertusa. Here we use an online preconcentration ICP-MS method (Hathorne et al. 2012) to measure REE concentrations in seawater and associated cold-water coral carbonates in order to investigate their seawater origin. Scleractinian cold-water corals were collected in-situ and alive and with corresponding seawater samples covering from the European Continental Margin. The seawater REE patterns are characterized by the typical negative cerium anomaly of seawater, but are distinct for the northern Norwegian Margin and the Oslo Fjord, probably related to continental input. Initial results for the corresponding coral samples suggest that these distinct REE patterns of ambient seawater are recorded by the coral skeletons although some fractionation during incorporation into the aragonite occurs. This indicates that scleractinian cold-water corals can serve as a valuable archive for seawater derived REE signatures, as well radiogenic Nd isotope compositions. In a second step we analysed fossil coral samples from various locations, which were oxidatively and reductively cleaned prior to analysis. Initial results reveal that sediment-buried fossil (early Pleistocene to Holocene) coral samples from the Norwegian Margin and the Porcupine Seabight (Challenger Mound, IODP Site 1317) do not show the expected seawater REE patterns. In particular, the fossil coral-derived REE patterns lack a negative cerium anomaly suggesting that fossil coral-REE patterns do not represent ambient seawater. Thus, we suggest that the oxidative-reductive cleaning method widely used for cleaning of marine carbonates such as foraminifera prior to measurements of seawater-derived trace metal and isotope compositions are not sufficient for REE and Nd isotopes in sediment-buried coral-water corals and require alternative or additional approaches. Hathorne, E.C., B. Haley, T. Stichel, P. Grasse, M. Zieringer, and M. Frank (2012). Online preconcentration ICP-MS analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in seawater, Geochem. Geophys. Geosyst.,13, Q01020, doi:10.1029/2011GC003907. .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V23D4829N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V23D4829N"><span id="translatedtitle">The Fluid History of Jadeitites Near the Motagua Fault, Guatemala, as Revealed by Stable Isotope and <span class="hlt">Elemental</span> <span class="hlt">Geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Niespolo, E. M.; Holk, G. J.; Neff, H.</p> <p>2014-12-01</p> <p>Stable isotopes and <span class="hlt">elemental</span> <span class="hlt">geochemistry</span> reveal a complex fluid history for jadeitites exposed both north and south of the Motagua Fault Zone (MFZ) in Guatemala. A companion study (Niespolo et al., 2014) utilized these data to source Mesoamerican jadeitite artifacts, as this region is the only source for such materials. Materials studied include jadeitites that range from 71% to 95% jadeite with minor albite and white mica. Jadeitites north of the MFZ have ?18OJadeite = +9.2±0.6‰ (n=6), ?18OAlbite = +9.4±0.3 (n=2), ?18OWhiteMica = +9.8±0.3 (n=3), and ?DWhiteMica = -52± 4‰ (n=3). Jadeite ?18O values are 2-5‰ higher than those reported by Johnson and Harlow (1999), suggesting a diverse fluid history north of the MFZ. Water in apparent equilibrium at 400°C with north MFZ jadeitite has ?18O = +8.5‰ and ?D = -25‰. Jadeites from Carrizal Grande south of the MFZ have ?18OJadeite = +6.8±0.6‰ (n=7), ?18OWhiteMica = +9.0±1.2 (n=6), and ?DWhiteMica = -42±2‰ (n=5), with ?18OH2O = +6.4‰ and ?DH2O = -15‰. In contrast, jadeitites from La Cieba south of the MFZ have ?18OJadeite = +7.5±1.4‰ (n=5), ?18OAlbite = +9.0, ?18OWhiteMica = +9.7±0.1 (n=2), and ?DWhiteMica = -42±0‰ (n=2), with ?18OH2O = +7.2‰ and ?DH2O = -14‰. Calculated fluids are consistent with those associated with the alteration of serpentinite in a subduction zone setting (e.g., Harlow and Sorenson, 2005). White mica, albite and jadeite are out of 18O/16O equilibrium. This suggests post-jadeite isotopic exchange, possibly during exhumation. North MFZ jadeites are enriched in Rb, Ba, Sc, Pb and Nd, and depleted in Sr, Ti, V, and Cr relative to chondrites. Carrizal Grande jadeites are depleted in Sr, Zr, V, and Cr, and enriched in REE and Rb.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.earth.ox.ac.uk/__data/assets/pdf_file/0009/22302/WH1v2.pdf','EPRINT'); return false;" href="http://www.earth.ox.ac.uk/__data/assets/pdf_file/0009/22302/WH1v2.pdf"><span id="translatedtitle">Project <span class="hlt">EARTH</span>-15-WH1: Trace <span class="hlt">element</span> cycling in the ocean's bottom boundary layer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Henderson, Gideon</p> <p></p> <p>Project <span class="hlt">EARTH</span>-15-WH1: Trace <span class="hlt">element</span> cycling in the ocean's bottom boundary layer Supervisors: Dr Will Homoky, Prof. Gideon Henderson (<span class="hlt">Earth</span> Sciences) The entire ocean floor is overlain by a bottom boundary layer of seawater that hosts dynamic properties[1] , able to moderate the release and uptake of <span class="hlt">elements</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.seismo.berkeley.edu/~kirchner/reprints/2001_49_snowmelt_tracers.pdf','EPRINT'); return false;" href="http://www.seismo.berkeley.edu/~kirchner/reprints/2001_49_snowmelt_tracers.pdf"><span id="translatedtitle">A study of solute transport mechanisms using rare <span class="hlt">earth</span> <span class="hlt">element</span> tracers and artificial rainstorms on snow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Kirchner, James W.</p> <p></p> <p>and Susan Taylor1,5 Abstract. Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) tracers and three artificial rain-on-snow stormsA study of solute transport mechanisms using rare <span class="hlt">earth</span> <span class="hlt">element</span> tracers and artificial rainstorms on snow Xiahong Feng,1 James W. Kirchner,2 Carl E. Renshaw,1 Randall S. Osterhuber,3 Bjo¨rn Klaue,4</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.earth.lsa.umich.edu/~mhren/Site/Publications_files/Barberton.pdf','EPRINT'); return false;" href="http://www.earth.lsa.umich.edu/~mhren/Site/Publications_files/Barberton.pdf"><span id="translatedtitle">Stable isotope and Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> evidence for recent ironstone pods within the Archean Barberton</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Hren, Michael</p> <p></p> <p>Stable isotope and Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> evidence for recent ironstone pods within the Archean greenstone belt. We examined oxygen and hydrogen isotopes and Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> (REE) concentrations of these Archean chemical sediments contain a high percentage of oxidized iron, frequently found in discrete</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/14582968','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/14582968"><span id="translatedtitle">Effects of spraying rare <span class="hlt">earths</span> on contents of rare <span class="hlt">Earth</span> <span class="hlt">elements</span> and effective components in tea.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Dongfeng; Wang, Changhong; Ye, Sheng; Qi, Hongtao; Zhao, Guiwen</p> <p>2003-11-01</p> <p>Rare <span class="hlt">earth</span> (RE) fertilizer is widely applied in China to increase the yield and the quality of crops including tea. However, the effects of spraying RE fertilizer on the contents of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) and effective components in tea are unknown. The results from basin and field experiments show that the values of the REE concentrations in new shoots of tea plants and the concentration of REE in the soil (REE/REEs) either from control basins or from treatment basins were smaller than those in other parts of tea plant and similar between control and treatment. The longer the interval between spraying RE fertilizer and picking the shoots of tea plants, the less the effects from spraying. About 80% summation operator REE (the sum of the concentrations of 15 REE) in tea, whether it came from spraying or not, was insoluble in the infusion. About 10% the soluble REE of summation operator REE in tea infusion was bound to polysaccharide, and the amount of REE bound polysaccharide decreased over time. At least a 25 day safety interval is needed between spraying and picking if the microelement fertilizer is used, in order to enhance tea output and to ensure tea safety. PMID:14582968</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/2011/1256/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2011/1256/"><span id="translatedtitle">Carbonatite and alkaline intrusion-related rare <span class="hlt">earth</span> <span class="hlt">element</span> deposits–A deposit model</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Verplanck, Philip L.; Van Gosen, Bradley S.</p> <p>2011-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> are not as rare in nature as their name implies, but economic deposits with these <span class="hlt">elements</span> are not common and few deposits have been large producers. In the past 25 years, demand for rare <span class="hlt">earth</span> <span class="hlt">elements</span> has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare <span class="hlt">earth</span> <span class="hlt">elements</span> come from only a few sources. China produces more than 95 percent of the world's supply of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Because of China's decision to restrict exports of these <span class="hlt">elements</span>, the price of rare <span class="hlt">earth</span> <span class="hlt">elements</span> has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare <span class="hlt">earth</span> <span class="hlt">elements</span> deposits, and identifying and quantifying our nation's rare <span class="hlt">earth</span> <span class="hlt">elements</span> resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. The general mineral deposit model summarized here is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Carbonatite and alkaline intrusion-related REE deposits are discussed together because of their spatial association, common enrichment in incompatible <span class="hlt">elements</span>, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare <span class="hlt">earth</span> <span class="hlt">elements</span>, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120001844','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001844"><span id="translatedtitle">Core-Mantle Partitioning of Volatile Siderophile <span class="hlt">Elements</span> and the Origin of Volatile <span class="hlt">Elements</span> in the <span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nickodem, K.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.</p> <p>2012-01-01</p> <p>There are currently several hypotheses on the origin of volatile siderophile <span class="hlt">elements</span> in the <span class="hlt">Earth</span>. One hypothesis is that they were added during <span class="hlt">Earth</span> s accretion and core formation and mobilized into the metallic core [1], others claim multiple stage origin [2], while some hypothesize that volatiles were added after the core already formed [3]. Several volatile siderophile <span class="hlt">elements</span> are depleted in <span class="hlt">Earth</span> s mantle relative to the chondrites, something which continues to puzzle many scientists. This depletion is likely due to a combination of volatility and core formation. The <span class="hlt">Earth</span> s core is composed of Fe and some lighter constituents, although the abundances of these lighter <span class="hlt">elements</span> are unknown [4]. Si is one of these potential light <span class="hlt">elements</span> [5] although few studies have analyzed the effect of Si on metal-silicate partitioning, in particular the volatile <span class="hlt">elements</span>. As, In, Ge, and Sb are trace volatile siderophile <span class="hlt">elements</span> which are depleted in the mantle but have yet to be extensively studied. The metal-silicate partition coefficients of these <span class="hlt">elements</span> will be measured to determine the effect of Si. Partition coefficients depend on temperature, pressure, oxygen fugacity, and metal and silicate composition and can constrain the concentrations of volatile, siderophile <span class="hlt">elements</span> found in the mantle. Reported here are the results from 13 experiments examining the partitioning of As, In, Ge, and Sb between metallic and silicate liquid. These experiments will examine the effect of temperature, and metal-composition (i.e., Si content) on these <span class="hlt">elements</span> in or-der to gain a greater understanding of the core-mantle separation which occurred during the <span class="hlt">Earth</span> s early stages. The data can then be applied to the origin of volatile <span class="hlt">elements</span> in the <span class="hlt">Earth</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014CoMP..167.1002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014CoMP..167.1002S"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of ultrahigh-pressure anatexis: fractionation of <span class="hlt">elements</span> in the Kokchetav gneisses during melting at diamond-facies conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stepanov, Aleksandr S.; Hermann, Joerg; Korsakov, Andrey V.; Rubatto, Daniela</p> <p>2014-05-01</p> <p>The Kokchetav complex in Kazakhstan contains garnet-bearing gneisses that formed by partial melting of metasedimentary rocks at ultrahigh-pressure (UHP) conditions. Partial melting and melt extraction from these rocks is documented by a decrease in K2O and an increase in FeO + MgO in the restites. The most characteristic trace <span class="hlt">element</span> feature of the Kokchetav UHP restites is a strong depletion in light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE), Th and U. This is attributed to complete dissolution of monazite/allanite in the melt and variable degree of melt extraction. In contrast, Zr concentrations remain approximately constant in all gneisses. Using experimentally determined solubilities of LREE and Zr in high-pressure melts, these data constrain the temperature of melting to ~1,000 °C. Large ion lithophile <span class="hlt">elements</span> (LILE) are only moderately depleted in the samples that have the lowest U, Th and LREE contents, indicating that phengite retains some LILE in the residue. Some restites display an increase in Nb/Ta with respect to the protolith. This further suggests the presence of phengite, which, in contrast to rutile, preferentially incorporates Nb over Ta. The trace <span class="hlt">element</span> fractionation observed during UHP anatexis in the Kokchetav gneisses is significantly different from depletions reported in low-pressure restites, where generally no LREE and Th depletion occurs. Melting at UHP conditions resulted in an increase in the Sm/Nd ratio and a decoupling of the Sm-Nd and Lu-Hf systems in the restite. Further subduction of such restites and mixing with mantle rocks might thus lead to a distinct isotopic reservoir different from the bulk continental crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B11C0036Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B11C0036Y"><span id="translatedtitle">Investigating Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Systematics in the Marcellus Shale</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, J.; Torres, M. E.; Kim, J. H.; Verba, C.</p> <p>2014-12-01</p> <p>The lanthanide series of <span class="hlt">elements</span> (the 14 rare <span class="hlt">earth</span> <span class="hlt">elements</span>, REEs) have similar chemical properties and respond to different chemical and physical processes in the natural environment by developing unique patterns in their concentration distribution when normalized to an average shale REE content. The interpretation of the REE content in a gas-bearing black shale deposited in a marine environment must therefore take into account the paleoredox conditions of deposition as well as any diagenetic remobilization and authigenic mineral formation. We analyzed 15 samples from a core of the Marcellus Shale (Whipkey ST1, Greene Co., PA) for REEs, TOC, gas-producing potential, trace metal content, and carbon isotopes of organic matter in order to determine the REE systematics of a black shale currently undergoing shale gas development. We also conducted a series of sequential leaching experiments targeting the phosphatic fractions in order to evaluate the dominant host phase of REEs in a black shale. Knowledge of the REE system in the Marcellus black shale will allow us to evaluate potential REE release and behavior during hydraulic fracturing operations. Total REE content of the Whipkey ST1 core ranged from 65-185 ?g/g and we observed three distinct REE shale-normalized patterns: middle-REE enrichment (MREE/MREE* ~2) with heavy-REE enrichment (HREE/LREE ~1.8-2), flat patterns, and a linear enrichment towards the heavy-REE (HREE/LREE ~1.5-2.5). The MREE enrichment occurred in the high carbonate samples of the Stafford Member overlying the Marcellus Formation. The HREE enrichment occurred in the Union Springs Member of the Marcellus Formation, corresponding to a high TOC peak (TOC ~4.6-6.2 wt%) and moderate carbonate levels (CaCO3 ~4-53 wt%). Results from the sequential leaching experiments suggest that the dominant host of the REEs is the organic fraction of the black shale and that the detrital and authigenic fractions have characteristic MREE enrichments. We present our conclusions on the impact of depositional setting and diagenetic remobilization and authigenic mineral formation on the REE system in the Marcellus Shale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4260943','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4260943"><span id="translatedtitle">Recovery and Separation of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Using Salmon Milt</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Takahashi, Yoshio; Kondo, Kazuhiro; Miyaji, Asami; Watanabe, Yusuke; Fan, Qiaohui; Honma, Tetsuo; Tanaka, Kazuya</p> <p>2014-01-01</p> <p>Recycling rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020068','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020068"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> metasomatism in hydrothermal systems: The Willsboro-Lewis wollastonite ores, New York, USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Whitney, P.R.; Olmsted, J.F.</p> <p>1998-01-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">geochemistry</span> may be useful in discerning the origin of skarns and skarn-related ore deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984gord.book.....H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984gord.book.....H"><span id="translatedtitle"><span class="hlt">Geochemistry</span> and origin of regional dolomites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hanson, G. N.</p> <p></p> <p>Quantitative, geochemical models for the source, flow paths and chemistry of the diagnetic fluids responsible for the widespread dolomitization of the Mississippi Burlington-Keokuk Fms were developed. Iowa, Illinois and Missouri by integrating <span class="hlt">geochemistry</span>, fluid inclusion studies, conventional and luminescent petrography, stratigraphy, facies analysis and burial history. The study includes western Illinois and eastern Missouri and southeastern Iowa. This includes most of the area where good sections of facies from near shore to the platform edge. The geochemical studies include: correlation of the major and trace <span class="hlt">element</span> variations within the various Burlington dolomites developed in southeastern Iowa and adjacent areas of Illinois and Missouri; rare <span class="hlt">earth</span> <span class="hlt">element</span>, Nd and Sr isotope analysis of the dolomites and coexisting phases; major and trace <span class="hlt">element</span> analysis, petrography and X ray mineralogy of selected shaly members in the Burlington-Keokuk formations; and fluid inclusion studies of the calcites and dolomite cements of southeastern Iowa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V33G..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V33G..01S"><span id="translatedtitle">Investigation of Chemical and Physical Changes to Bioapatite During Fossilization Using Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span>, Infrared Spectroscopy and Stable Isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suarez, C. A.; Kohn, M. J.</p> <p>2013-12-01</p> <p>Bioapatite in the form of vertebrate bone can be used for a wide variety of paleo-proxies, from determination of ancient diet to the isotopic composition of meteoric water. Bioapatite alteration during diagenesis is a constant barrier to the use of fossil bone as a paleo-proxy. To elucidate the physical and chemical alteration of bone apatite during fossilization, we analyzed an assortment of fossil bones of different ages for trace <span class="hlt">elements</span>, using LA-ICP-MS, stable isotopes, and reflected IR spectroscopy. One set of fossil bones from the Pleistocene of Idaho show a diffusion recrystallization profile, however, rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) profiles indicate diffusion adsorption. This suggests that REE diffusion is controlled by changing (namely decreasing) boundary conditions (i.e. decreasing concentration of REE in surrounding pore fluids). Reflected IR analysis along this concentration profile reveal that areas high in U have lost type A carbonate from the crystal structure in addition to water and organics. Stable isotopic analysis of carbon and oxygen will determine what, if any, change in the isotopic composition of the carbonate component of apatite has occurred do to the diffusion and recrystallization process. Analysis of much older bone from the Cretaceous of China reveal shallow REE and U concentration profiles and very uniform reflected IR spectra with a significant loss of type A carbonate throughout the entire bone cortex. Analysis of stable isotopes through the bone cortex will be compared to the stable isotopes collected from the Pleistocene of Idaho.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CoMP..170...11S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CoMP..170...11S"><span id="translatedtitle">Genesis of the central zone of the Nolans Bore rare <span class="hlt">earth</span> <span class="hlt">element</span> deposit, Northern Territory, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schoneveld, Louise; Spandler, Carl; Hussey, Kelvin</p> <p>2015-08-01</p> <p>The Nolans Bore rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) deposit consists of a network of fluorapatite-bearing veins and breccias hosted within Proterozoic granulites of the Reynolds Range, Central Australia. Mineralisation is divided into three zones (north, central, and south-east), with the north and south-east zones consisting of massive REE-bearing fluorapatite veins, with minor brecciation and carbonate infill. The central zone is distinctively different in mineralogy and structure; it features extensive brecciation, a high allanite content, and a large, epidote-rich enveloping alteration zone. The central zone is a reworking of the original solid apatite veins that formed during the Chewings Orogeny at ca. 1525 Ma. These original apatite veins are thought to derive from phosphate-rich magmatic-hydrothermal fluid exsolved from as-yet unrecognised alkaline magmatic bodies at depth. We define four ore breccia types (BX1-4) in the central zone on the basis of detailed petrological and geochemical analysis of drillcore and thin sections. BX1 ore comprises fluorapatite with minor crackle brecciation with carbonate infill and resembles ore of the north and south-east zones. Breccia types BX2, BX3, and BX4 represent progressive stages of ore brecciation and development of calc-silicate mineral (amphibole, epidote, allanite, calcite) infill. Comparison of bulk ore sample <span class="hlt">geochemistry</span> between breccia types indicates that REEs were not mobilised more than a few centimetres during hydrothermal alteration and brecciation. Instead, most of the REEs were partitioned from the original REE fluorapatite into newly formed allanite, REE-poor fluorapatite and minor REE carbonate in the breccias. Negative europium (Eu) anomalies in the breccia minerals are accounted for by a large positive Eu anomaly in epidote from the alteration zones surrounding the ore breccias. This observation provides a direct link between ore recrystallisation and brecciation, and the formation of the alteration halo in the surrounding host rocks. Where allanite and fluorapatite are texturally related, the fluorapatite is relatively depleted in the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREEs), whereas allanite is relatively LREE enriched, suggesting co-crystallisation. We tentatively date the BX1 ore stage to 1440 ± 80 Ma based on U-Pb dating of thorianite. Sm-Nd isotope isochrons derived from in situ isotope analysis of cognate apatite and allanite date the BX2 and BX3 events to ca. 400 Ma, while U-Pb dating of late-stage monazite from the BX4 ore stage returned an age of ca. 350 Ma. Therefore, formation of the central zone at Nolans Bore involved multiple alteration/brecciation events that collectively span over 1 billion years in duration. We suggest that the BX1-type veins and breccias were formed from REE-rich, saline (F- and Cl-bearing) fluids that infiltrated the granulite-grade host rocks in association with either shear activation events of the Redbank Shear Zone (1500-1400 Ma) or intrusion of late-stage pegmatites of the Mt Boothby area. BX2, BX3, and BX4 events record deformation and hydrothermal alteration associated with the Alice Springs Orogeny (400-350 Ma). These hydrothermal events occurred at temperatures of 450 to ~600 °C, due to inflow of highly acidic hydrous fluids derived from a magmatic source, or from mixing of meteoric and metamorphic fluids. Our data testify to the long and complex geological history of not only the Nolans Bore REE deposit, but also of the rocks of the eastern Reynolds Range, and demonstrate the great utility of using hydrothermally derived REE minerals to trace the timing of crustal deformation events and source of associated hydrothermal fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=251706&keyword=human+AND+resource+AND+management&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=55240349&CFTOKEN=73368070','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=251706&keyword=human+AND+resource+AND+management&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=55240349&CFTOKEN=73368070"><span id="translatedtitle">RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENTS</span>: A REVIEW OF PRODUCTION, PROCESSING, RECYCLING, AND ASSOCIATED ENVIRONMENTAL ISSUES</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are a group of 15 chemical <span class="hlt">elements</span> in the periodic table, specifically the lanthanides. Two other <span class="hlt">elements</span>, scandium and yttrium, have a similar physiochemistry to the lanthanides, are commonly found in the same mineral assemblages, and are often refe...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010754','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010754"><span id="translatedtitle">Biogeochemistry of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> with particular reference to hickory trees</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Robinson, W.O.; Bastron, H.; Murata, K.J.</p> <p>1958-01-01</p> <p>Hickory trees concentrate the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in their leaves to a phenomenal degree and may contain as much as 2300 p.p.m. of total rare <span class="hlt">earths</span> based on the dry weight of the leaves. The average proportions of the individual <span class="hlt">elements</span> (atomic percent of the total rare-<span class="hlt">earth</span> <span class="hlt">elements</span>) in the leaves are: Y 36, La 16, Ce 14, Pr 2, Nd 20, Sm 1, Eu 0.7, Gd 3, Tb 0.6, Dy 3, Ho 0.7, Er 2, Tm 0.2, Yb 1, and Lu 0.2. The similarity in the proportions of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in the leaves and in the exchange complex of the soil on which the hickory trees grow indicates that the trees do not fractionate the rare <span class="hlt">earths</span> appreciably. The variation of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in the leaves and soils can be explained generally in terms of the relative abundance of the cerium group and the yttrium group, except for the <span class="hlt">element</span> cerium. The large fluctuations in the proportion of cerium [Ce/(La + Nd) atomic ratios of 0.16 to 0.86] correlate with oxidation-reduction conditions in the soil profile. The substitution of dilute H2SO3 for dilute HC1 in the determination of available rare-<span class="hlt">earth</span> <span class="hlt">elements</span> brings about a large increase in the proportion of cerium that is extracted from an oxygenated subsoil. These relationships strongly suggest that quadrivalent cerium is present in oxygenated subsoil and is less available to plants than the other rare-<span class="hlt">earth</span> <span class="hlt">elements</span> that do not undergo such a change in valence. A few parts per billion of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> have been detected in two samples of ground water. ?? 1958.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985JGR....90.8743C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JGR....90.8743C"><span id="translatedtitle">Trace <span class="hlt">element</span> and isotopic <span class="hlt">geochemistry</span> of lavas from Haleakala Volcano, east Maui, Hawaii: Implications for the origin of Hawaiian basalts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Chu-Yung; Frey, Frederick A.</p> <p>1985-09-01</p> <p>Haleakala volcano on East Maui, Hawaii, consists of a tholeiitic basalt shield which grades into a younger alkalic series that was followed by a posterosional alkalic series. Tholeiitic, transitional, and alkalic basalts range widely in Sr and Nd isotopic ratios (from mid-ocean ridge basalt to bulk <span class="hlt">earth</span> ratios) and incompatible <span class="hlt">element</span> (P, K, Rb, Sr, Zr, Nb, Ba, REE, Hf, Ta, and Th) abundances, but isotopic ratios and incompatible <span class="hlt">element</span> abundance ratios (e.g., Ba/La, Nb/La, La/Ce, La/Sm) vary systematically with age. The youngest series (posterosional alkalic lavas) has the highest Rb/Sr, Ba/La, Nb/La, La/Ce, and 143Nd/144Nd ratios and the lowest 87sr/86sr ratios, whereas the oldest series (dominantly tholeiitic basalts) has the lowest Rb/Sr, Ba/La, Nb/La, La/Ce, and 143Nd/144Nd ratios and the highest 87sr/86sr ratios. The most striking features of the trace <span class="hlt">element</span> and isotopic data are the inverse correlations between isotopic ratios and parent/daughter abundance ratios in the Sr and Nd systems. Although some of the geochemical variations can be explained by shallow level fractional crystallization (e.g., alkali basalt to mugearite [Chen et al., 1984, and manuscript in preparation, 1985]), the temporal geochemical trends require a major role for mixing. We propose a model in which melts from a diaper interact with incipient melts of its wall rocks, presumed to be oceanic lithosphere. Because of motion between the lithosphere and mantle hot spot the relative contribution of melts from the diapir (mantle plume) material to the lavas decreases with time; consequently, with decreasing age the basalts become more enriched in incompatible trace <span class="hlt">elements</span> and acquire Sr and Nd isotopic ratios which overlap with mid-ocean ridge basalts. This model quantitatively explains the isotopic ratios and incompatible trace <span class="hlt">element</span> abundances in representative samples from the three Haleakala volcanic series. On the basis of the degrees of melting inferred for the mixing components we conclude that the lower lithosphere and much of the asthenosphere beneath Hawaiian volcanoes are involved in creating these volcanoes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAESc.105..300S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAESc.105..300S"><span id="translatedtitle">Platinum Group <span class="hlt">Elements</span> (PGE) <span class="hlt">geochemistry</span> of komatiites and boninites from Dharwar Craton, India: Implications for mantle melting processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saha, Abhishek; Manikyamba, C.; Santosh, M.; Ganguly, Sohini; Khelen, Arubam C.; Subramanyam, K. S. V.</p> <p>2015-06-01</p> <p>High MgO volcanic rocks having elevated concentrations of Ni and Cr are potential hosts for platinum group <span class="hlt">elements</span> (PGE) owing to their primitive mantle origin and eruption at high temperatures. Though their higher PGE abundance is economically significant in mineral exploration studies, their lower concentrations are also valuable geochemical tools to evaluate petrogenetic processes. In this paper an attempt has been made to evaluate the PGE <span class="hlt">geochemistry</span> of high MgO volcanic rocks from two greenstone belts of western and eastern Dharwar Craton and to discuss different mantle processes operative at diverse geodynamic settings during the Neoarchean time. The Bababudan greenstone belt of western and Gadwal greenstone belt of eastern Dharwar Cratons are dominantly composed of high MgO volcanic rocks which, based on distinct geochemical characteristics, have been identified as komatiites and boninites respectively. The Bababudan komatiites are essentially composed of olivine and clinopyroxene with rare plagioclase tending towards komatiitic basalts. The Gadwal boninites contain clinopyroxene, recrystallized hornblende with minor orthopyroxene, plagioclase and sulphide minerals. The Bababudan komatiites are Al-undepleted type (Al2O3/TiO2 = 23-59) with distinctly high MgO (27.4-35.8 wt.%), Ni (509-1066 ppm) and Cr (136-3036 ppm) contents. These rocks have low ?PGE (9-42 ppb) contents with 0.2-2.4 ppb Iridium (Ir), 0.2-1.4 ppb Osmium (Os) and 0.4-4.4 ppb Ruthenium (Ru) among Iridium group PGE (IPGE); and 1.4-16.2 ppb Platinum (Pt), 2.8-19 ppb Palladium (Pd) and 0.2-9.8 ppb Rhodium (Rh) among Platinum group PGE (PPGE). The Gadwal boninites are high-Ca boninites with CaO/Al2O3 ratios varying between 0.8 and 1.0, with 12-24 wt.% MgO, 821-1168 ppm Ni and 2307-2765 ppm Cr. They show higher concentration of total PGE (82-207 ppb) with Pt concentration ranging from 13 to 19 ppb, Pd between 65 and 180 ppb and Rh in the range of 1.4-3 ppb compared to the Bababudan komatiites. Ir, Os and Ru concentrations range from 0.6 to 2.2 ppb, 0.2 to 0.6 ppb and 1.4 to 2.6 ppb respectively in IPGE. The PGE abundances in Bababudan komatiites were controlled by olivine fractionation whereas that in Gadwal boninites were influenced by fractionation of chromite and sulphides. The Al-undepleted Bababudan komatiites are characterized by low CaO/Al2O3, (Gd/Yb)N, (La/Yb)N, with positive Zr, Hf, Ti anomalies and high Cu/Pd, Pd/Ir ratios at low Pd concentrations suggesting the derivation of parent magma by high degrees (>30%) partial melting of mantle under anhydrous conditions at shallow depth with garnet as a residual phase in the mantle restite. The komatiites are geochemically analogous to Al-undepleted Munro type komatiites and their PGE compositions are consistent with Alexo and Gorgona komatiites. The S-undersaturated character of Bababudan komatiites is attributed to decompression and assimilation of lower crustal materials during magma ascent and emplacement. In contrast, the higher Al2O3/TiO2, lower (Gd/Yb)N, for Gadwal boninites in combination with negative Nb, Zr, Hf, Ti anomalies and lower Cu/Pd at relatively higher Pd/Ir and Pd concentrations reflect high degree melting of refractory mantle wedge under hydrous conditions in an intraoceanic subduction zone setting. Higher Pd/Ir ratios and S-undersaturation of these boninites conform to influx of fluids derived by dehydration of subducted slab resulting into high fluid pressure and metasomatism of mantle wedge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21062438','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21062438"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span>: A Tool for Understanding the Behaviour of Trivalent Actinides in the Geosphere</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buil, Belen; Gomez, Paloma; Garralon, Antonio; Turrero, M. Jesus</p> <p>2007-07-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations have been determined in groundwaters, granite and fracture fillings in a restored uranium mine. The granitoids normalized REE patterns of groundwaters show heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> (HREE)-enrichment and positive Eu anomalies. This suggests that the REE are fractionated during leaching from the source rocks by groundwaters. Preferential leaching of HREE would be consistent with the greater stability of their aqueous complexes compared to those of the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE), together with the dissolution of certain fracture filling minerals, dissolution/alteration of phyllosilicates and colloidal transport. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020241','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020241"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in weathering profiles and sediments of Minnesota: Implications for provenance studies</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morey, G.B.; Setterholm, D.R.</p> <p>1997-01-01</p> <p>The relative abundance of rare <span class="hlt">earth</span> <span class="hlt">elements</span> 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 <span class="hlt">earth</span> <span class="hlt">elements</span> are mobilized and fractionated by weathering, and that sediments derived from the weathered materials can display modifications of the original pattern of rare <span class="hlt">earth</span> <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=279057&keyword=earth&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=43028031&CFTOKEN=41140176','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=279057&keyword=earth&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=43028031&CFTOKEN=41140176"><span id="translatedtitle">Technical Information Resource on Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Now Available to Public and Private Sector Stakeholders</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>A new EPA technical information resource, “Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span>: A Review of Production, Processing, Recycling, and Associated Environmental Issues” has been produced as an introductory resource for those interested in learning more about REE mining and alternatives to meet demand...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980002855','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980002855"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Partition Coefficients from Enstatite/Melt Synthesis Experiments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schwandt, Craig S.; McKay, Gordon A.</p> <p>1997-01-01</p> <p>Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations were measured in both the basaltic glass and the enstatite. Rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare <span class="hlt">earth</span> <span class="hlt">element</span> partition signature for enstatite is similar to previous calculated and composite low-Ca pigeonite signatures, but is better defined and differs in several details. The partition coefficients are consistent with crystal structural constraints.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140003556','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140003556"><span id="translatedtitle">Core-Mantle Partitioning of Volatile <span class="hlt">Elements</span> and the Origin of Volatile <span class="hlt">Elements</span> in <span class="hlt">Earth</span> and Moon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, Kevin; Pando, K.; Danielson, L.; Nickodem, K.</p> <p>2014-01-01</p> <p>Depletions of volatile siderophile <span class="hlt">elements</span> (VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd) in mantles of <span class="hlt">Earth</span> and Moon, constrain the origin of volatile <span class="hlt">elements</span> in these bodies, and the overall depletion of volatile <span class="hlt">elements</span> in Moon relative to <span class="hlt">Earth</span>. A satisfactory explanation has remained elusive [1,2]. We examine the depletions of VSE in <span class="hlt">Earth</span> and Moon and quantify the amount of depletion due to core formation and volatility of potential building blocks. We calculate the composition of the <span class="hlt">Earth</span>'s PUM during continuous accretion scenarios with constant and variable fO2. Results suggest that the VSE can be explained by a rather simple scenario of continuous accretion leading to a high PT metal-silicate equilibrium scenario that establishes the siderophile <span class="hlt">element</span> content of <span class="hlt">Earth</span>'s PUM near the end of accretion [3]. Core formation models for the Moon explain most VSE, but calculated contents of In, Sn, and Zn (all with Tc < 750 K) are all still too high after core formation, and must therefore require an additional process to explain the depletions in the lunar mantle. We discuss possible processes including magmatic degassing, evaporation, condensation, and vapor-liquid fractionation in the lunar disk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.140..177F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.140..177F"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and neodymium isotopes in sedimentary organic matter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure</p> <p>2014-09-01</p> <p>We report rare <span class="hlt">earth</span> <span class="hlt">element</span> (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 ?REE = 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 ?Nd values that typically range between the ?Nd 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 ?Nd 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70035639','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70035639"><span id="translatedtitle">U-Pb SHRIMP geochronology and trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of coesite-bearing zircons, North-East Greenland Caledonides</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McClelland, W.C.; Power, S.E.; Gilotti, J.A.; Mazdab, F.K.; Wopenka, B.</p> <p>2006-01-01</p> <p>Obtaining reliable estimates for the timing of eclogite-facies metamorphism is critical to establishing models for the formation and exhumation of high-pressure and ultrahigh-pressure (UHP) metamorphic terranes in collisional orogens. The presence of pressure-dependent phases, such as coesite, included in metamorphic zircon is generally regarded as evidence that zircon growth occurred at UHP conditions and, ifdated, should provide the necessary timing information. We report U-Pb sensitive high-resolution ion microprobe (SHRIMP) ages and trace-<span class="hlt">element</span> SHRIMP data from coesite-bearing zircon suites formed during UHP metamorphism in the North- East Greenland Caledonides. Kyanite eclogite and quartzofeldspathic host gneiss samples from an island in J??kelbugt (78??00'N, 18??04'W) contained subspherical zircons with well-defined domains in cathodoluminescence (CL) images. The presence of coesite is confirmed by Raman spectroscopy in six zircons from four samples. Additional components of the eclogite-facies inclusion suite include kyanite, omphacite, garnet, and rutile. The trace-<span class="hlt">element</span> signatures in core domains reflect modification of igneous protolith zircon. Rim signatures show flat heavy rare <span class="hlt">earth</span> <span class="hlt">element</span> (HREE) patterns that are characteristic of eclogite-facies zircon. The kyanite eclogites generally lack a Eu anomaly, whereas a negative Eu anomaly persists in all domains of the host gneiss. The 207Pb- corrected 206Pb/238U ages range from 330 to 390 Ma for the host gneiss and 330-370 Ma for the kyanite eclogite. Weighted mean 206Pb/238U ages for coesite-bearing domains vary from 364 ?? 8 Ma for the host gneiss to 350 ?? 4 Ma for kyanite eclogite. The combined U-Pb and REE data interpreted in conjunction with observed CL domains and inclusion suites suggest that (1) Caledonian metamorphic zircon formed by both new zircon growth and recrystallization, (2) UHP metamorphism occurred near the end of the Caledonian collision, and (3) the 30-50m.y. span of ages records long residence times at eclogite-facies conditions for the UHProcks of North-East Greenland. This spread in observed ages is interpreted to be characteristic of metamorphic rocks that have experienced relatively long (longer than 10 m.y.) residence times at UHP conditions. ?? 2006 Geological Society of America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000040791','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000040791"><span id="translatedtitle">Geochemical Constraints on Core Formation in the <span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, John H.; Drake, Michael J.</p> <p>1986-01-01</p> <p>New experimental data on the partitioning of siderophile and chalcophile <span class="hlt">elements</span> among metallic and silicate phases may be used to constrain hypotheses of core formation in the <span class="hlt">Earth</span>. Three current hypotheses can explain gross features of mantle <span class="hlt">geochemistry</span>, but none predicts siderophile and chalcophile <span class="hlt">element</span> abundances to within a factor of two of observed values. Either our understanding of metal-silicate interactions and/or our understanding of the early <span class="hlt">Earth</span> requires revision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://arxiv.org/pdf/1504.01421.pdf','EPRINT'); return false;" href="http://arxiv.org/pdf/1504.01421.pdf"><span id="translatedtitle">Highly Siderophile <span class="hlt">Elements</span> in the <span class="hlt">Earth</span>'s Mantle as a Clock for the Moon-forming Impact</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Jacobson, Seth A; Raymond, Sean N; O'Brien, David P; Walsh, Kevin J; Rubie, David C</p> <p>2015-01-01</p> <p>According to the generally accepted scenario, the last giant impact on the <span class="hlt">Earth</span> formed the Moon and initiated the final phase of core formation by melting the <span class="hlt">Earth</span>'s mantle. A key goal of <span class="hlt">geochemistry</span> is to date this event, but different ages have been proposed. Some argue for an early Moon-forming event, approximately 30 million years (Myr) after the condensation of the first solids in the Solar System, whereas others claim a date later than 50 Myr (and possibly as late as around 100 My) after condensation. Here we show that a Moon-forming event at 40 Myr after condensation, or earlier, is ruled out at a 99.9 per cent confidence level. We use a large number of N-body simulations to demonstrate a relationship between the time of the last giant impact on an <span class="hlt">Earth</span>-like planet and the amount of mass subsequently added during the era known as Late Accretion. As the last giant impact is delayed, the late-accreted mass decreases in a predictable fashion. This relationship exists within both the classical scenario...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24835593','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24835593"><span id="translatedtitle">Experimental productivity rate optimization of rare <span class="hlt">earth</span> <span class="hlt">element</span> separation through preparative solid phase extraction chromatography.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Knutson, Hans-Kristian; Max-Hansen, Mark; Jönsson, Christian; Borg, Niklas; Nilsson, Bernt</p> <p>2014-06-27</p> <p>Separating individual rare <span class="hlt">earth</span> <span class="hlt">elements</span> from a complex mixture with several <span class="hlt">elements</span> is difficult and this is emphasized for the middle <span class="hlt">elements</span>: Samarium, Europium and Gadolinium. In this study we have accomplished an overloaded one-step separation of these rare <span class="hlt">earth</span> <span class="hlt">elements</span> through preparative ion-exchange high-performance liquid chromatography with an bis (2-ethylhexyl) phosphoric acid impregnated column and nitric acid as eluent. An inductively coupled plasma mass spectrometry unit was used for post column <span class="hlt">element</span> detection. The main focus was to optimize the productivity rate, subject to a yield requirement of 80% and a purity requirement of 99% for each <span class="hlt">element</span>, by varying the flow rate and batch load size. The optimal productivity rate in this study was 1.32kgSamarium/(hmcolumn(3)), 0.38kgEuropium/(hmcolumn(3)) and 0.81kgGadolinium/(hmcolumn(3)). PMID:24835593</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=arid&pg=4&id=EJ276909','ERIC'); return false;" href="http://eric.ed.gov/?q=arid&pg=4&id=EJ276909"><span id="translatedtitle">Exploration <span class="hlt">Geochemistry</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Closs, L. Graham</p> <p>1983-01-01</p> <p>Contributions in mineral-deposit model formulation, geochemical exploration in glaciated and arid environments, analytical and sampling problems, and bibliographic research were made in symposia held and proceedings volumes published during 1982. Highlights of these symposia and proceedings and comments on trends in exploration <span class="hlt">geochemistry</span> are…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=139557','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=139557"><span id="translatedtitle">RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENT</span> OXIDES FOR TRACING SEDIMENT MOVEMENT</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The development of soil conservation plans and evaluation of spatially distributed erosion models require knowledge of rates of soil loss and sedimentation on different landscape <span class="hlt">elements</span> and slope positions. Characterization of soil erosion rates and patterns within watersheds is important for the ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.V51D0316P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.V51D0316P"><span id="translatedtitle">The Toxicological <span class="hlt">Geochemistry</span> of Dusts, Soils, and Other <span class="hlt">Earth</span> Materials: Insights From In Vitro Physiologically-based Geochemical Leach Tests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Plumlee, G. S.; Ziegler, T. L.; Lamothe, P.; Meeker, G. P.; Sutley, S.</p> <p>2003-12-01</p> <p>Exposure to mineral dusts, soils, and other <span class="hlt">earth</span> materials results in chemical reactions between the materials and different body fluids that include, depending upon the exposure route, lung fluids, gastrointestinal fluids, and perspiration. In vitro physiologically-based geochemical leach tests provide useful insights into these chemical reactions and their potential toxicological implications. We have conducted such leach tests on a variety of <span class="hlt">earth</span> materials, including asbestos, volcanic ash, dusts from dry lake beds, mine wastes, wastes left from the roasting of mercury ores, mineral processing wastes, coal dusts and coal fly ash, various soils, and complex dusts generated by the World Trade Center collapse. Size-fractionated samples of <span class="hlt">earth</span> materials that have been well-characterized mineralogically and chemically are reacted at body temperature (37 C) for periods from 2 hours up to multiple days with various proportions of simulated lung, gastric, intestinal, and/or plasma-based fluids. Results indicate that different <span class="hlt">earth</span> materials may have quite different solubility and dissolution behavior in vivo, depending upon a) the mineralogic makeup of the material, and b) the exposure route. For example, biodurable minerals such as asbestos and volcanic ash particles, whose health effects result because they dissolve very slowly in vivo, bleed off low levels of trace metals into the simulated lung fluids; these include metals such as Fe and Cr that are suspected by health scientists of contributing to the generation of reactive oxygen species and resulting DNA damage in vivo. In contrast, dry lake bed dusts and concrete-rich dusts are highly alkaline and bioreactive, and cause substantial pH increases and other chemical changes in the simulated body fluids. Many of the <span class="hlt">earth</span> materials tested contain a variety of metals that can be quite soluble (bioaccessible), depending upon the material and the simulated body fluid composition. For example, due to their acidic pH and high chloride concentrations, simulated gastric fluids are most efficient at solubilizing metals such as Hg, Pb, Zn, and others that form strong chloride complexes; although these metals tend to partially reprecipitate in the near-neutral simulated intestinal fluids, complexes with organic ligands (i.e., amino and carboxylic acids) enhance their solubility. These metals are also quite soluble in near-neutral, protein-rich plasma-based fluids because they form strong complexes with the proteins. In contrast, metalloids that form oxyanion species (such as As, Cr, Mo, W) are commonly more soluble in near-neutral pH simulated lung fluids than in simulated gastric fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.128...29H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.128...29H"><span id="translatedtitle">Preservation of NOM-metal complexes in a modern hyperalkaline stalagmite: Implications for speleothem trace <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hartland, Adam; Fairchild, Ian J.; Müller, Wolfgang; Dominguez-Villar, David</p> <p>2014-03-01</p> <p>We report the first quantitative study of the capture of colloidal natural organic matter (NOM) and NOM-complexed trace metals (V, Co, Cu, Ni) in speleothems. This study combines published NOM-metal dripwater speciation measurements with high-resolution laser ablation ICPMS (LA-ICPMS) and sub-annual stable isotope ratio (?18O and ?13C), fluorescence and total organic carbon (TOC) analyses of a fast-growing hyperalkaline stalagmite (pH ˜11) from Poole’s Cavern, Derbyshire UK, which formed between 1997 and 2008 AD. We suggest that the findings reported here elucidate trace <span class="hlt">element</span> variations arising from colloidal transport and calcite precipitation rate changes observed in multiple, natural speleothems deposited at ca. pH 7-8. We find that NOM-metal(aq) complexes on the boundary between colloidal and dissolved (˜1 nm diameter) show an annual cyclicity which is inversely correlated with the alkaline <span class="hlt">earth</span> metals and is explained by calcite precipitation rate changes (as recorded by kinetically-fractionated stable isotopes). This relates to the strength of the NOM-metal complexation reaction, resulting in very strongly bound metals (Co in this system) essentially recording NOM co-precipitation (ternary complexation). More specifically, empirical partition coefficient (Kd) values between surface-reactive metals (V, Co, Cu, Ni) [expressed as ratio of trace <span class="hlt">element</span> to Ca ratios in calcite and in solution] arise from variations in the ‘free’ fraction of total metal in aqueous solution (fm). Hence, differences in the preservation of each metal in calcite can be explained quantitatively by their complexation behaviour with aqueous NOM. Differences between inorganic Kd values and field measurements for metal partitioning into calcite occur where [free metal] ? [total metal] due to complexation reactions between metals and organic ligands (and potentially inorganic colloids). It follows that where fm ? 0, apparent inorganic Kd app values are also ?0, but the true partition coefficient (Kd actual) is significantly higher. Importantly, the Kd of NOM-metal complexes [organic carbon-metal ratio) approaches 1 for the most stable aqueous complexes, as is shown here for Co, but has values of 24-150 for V, Ni and Cu. This implies that ternary surface complexation (metal-ligand co-adsorption) can occur (as for NOM-Co), but is the exception rather than the rule. We also demonstrate the potential for trace metals to record information on NOM composition as expressed through changing NOM-metal complexation patterns in dripwaters. Therefore, a suite of trace metals in stalagmites show variations clearly attributable to changes in organic ligand concentration and composition, and which potentially reflect the state of overlying surface ecosystems. The heterogeneous speciation and size distribution of aqueous NOM and metals (Lead and Wilkinson, 2006; Aiken et al., 2011). The variability in NOM-metal transport in caves that arises from the interaction between infiltration, flow routing, and the hydrodynamic properties of the fine colloids and particulates (Hartland et al., 2012). Variable dissociation kinetics through time as a function of (a) (Hartland et al., 2011). The surface charge of calcite and the availability of CaCO3 lattice sites as well as increased incidence of crystallographic defects with implications for incorporation of a range of trace species (Fairchild and Treble, 2009; Fairchild and Hartland, 2010). Thus, incorporation in speleothem calcite with consistent surface site properties will be determined by: The size and composition (i.e. hydrophilicity/hydrophobicity) of the NOM ligand, affecting adsorption and stability at the calcite surface. The lability (i.e. exchangeability) of the complexed metal and its binding affinity for the calcite surface. The concentration of aqueous complexes. Given the complexities, a partitioning approach to the problem is appropriate as a first approximation rather than a precise description. This study seeks to make the first quantitative connection between the organic and inorgani</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93..134S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93..134S"><span id="translatedtitle">U.S. trade dispute with China over rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Showstack, Randy</p> <p>2012-03-01</p> <p>The U.S. government has brought a new trade case against China over rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) as well as tungsten and molybdenum, President Barack Obama announced on 13 March. Japan and the European Union also have taken similar actions against China about REEs, which are a group of 17 chemically similar metallic <span class="hlt">elements</span> that are used in a variety of electronic, optical, magnetic, and catalytic applications. REEs are plentiful in the <span class="hlt">Earth</span>'s crust, although China currently has about 37% of the world's reserves and accounts for more than 95% of the world's production of the <span class="hlt">elements</span>, according to the British Geological Survey. The United States has requested consultations with China at the World Trade Organization (WTO) concerning “China's unfair export restraints on rare <span class="hlt">earths</span>, as well as tungsten and molybdenum,” the Office of the United States Trade Representative announced in a 13 March statement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JOM....66k2355K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JOM....66k2355K"><span id="translatedtitle">Addressing Rare-<span class="hlt">Earth</span> <span class="hlt">Element</span> Criticality: An Example from the Aviation Industry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.</p> <p>2014-11-01</p> <p>Rare-<span class="hlt">earth</span> (RE) <span class="hlt">elements</span> are enablers for a wide range of technologies, including high-strength permanent magnets, energy-efficient lighting, high-temperature thermal barrier coatings, and catalysts. While direct material substitution is difficult in many of these applications because of the specific electronic, optical, or electrochemical properties imparted by the individual rare-<span class="hlt">earth</span> <span class="hlt">elements</span>, we describe an example from the aviation industry where supply chain optimization may be an option. Ceramic matrix composite engine components require environmental barrier coatings (EBCs) to protect them from extreme temperatures and adverse reactions with water vapor in the hot gas path. EBC systems based on rare-<span class="hlt">earth</span> silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-<span class="hlt">earth</span> silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (HREEs) for phase stability. This article considers the possibility of using separation tailings containing a mixture of HREEs as a source material in lieu of using the high-purity HREE oxides. This option arises because the desired properties of RE-silicate EBCs derive from the average cation size rather than the electronic properties of the individual rare-<span class="hlt">earth</span> cations. Because separation tailings have not incurred the costs associated with the final stages of separation, they offer an economical alternative to high-purity oxides for this emerging application.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JOM...tmp..314K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JOM...tmp..314K"><span id="translatedtitle">Addressing Rare-<span class="hlt">Earth</span> <span class="hlt">Element</span> Criticality: An Example from the Aviation Industry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.</p> <p>2014-09-01</p> <p>Rare-<span class="hlt">earth</span> (RE) <span class="hlt">elements</span> are enablers for a wide range of technologies, including high-strength permanent magnets, energy-efficient lighting, high-temperature thermal barrier coatings, and catalysts. While direct material substitution is difficult in many of these applications because of the specific electronic, optical, or electrochemical properties imparted by the individual rare-<span class="hlt">earth</span> <span class="hlt">elements</span>, we describe an example from the aviation industry where supply chain optimization may be an option. Ceramic matrix composite engine components require environmental barrier coatings (EBCs) to protect them from extreme temperatures and adverse reactions with water vapor in the hot gas path. EBC systems based on rare-<span class="hlt">earth</span> silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-<span class="hlt">earth</span> silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (HREEs) for phase stability. This article considers the possibility of using separation tailings containing a mixture of HREEs as a source material in lieu of using the high-purity HREE oxides. This option arises because the desired properties of RE-silicate EBCs derive from the average cation size rather than the electronic properties of the individual rare-<span class="hlt">earth</span> cations. Because separation tailings have not incurred the costs associated with the final stages of separation, they offer an economical alternative to high-purity oxides for this emerging application.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26263628','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26263628"><span id="translatedtitle">[Leaching of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Coal Ashes Using Acidophilic Chemolithotrophic Microbial Communities].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Muravyov, M I; Bulaev, A G; Melamud, V S; Kondrat'eva, T F</p> <p>2015-01-01</p> <p>A method for leaching rare <span class="hlt">earth</span> <span class="hlt">elements</span> from coal ash in the presence of <span class="hlt">elemental</span> sulfur using communities of acidophilic chemolithotrophic microorganisms was proposed. The optimal parameters determined for rare <span class="hlt">element</span> leaching in reactors were as follows: temperature, 45 degrees C; initial pH, 2.0; pulp density, 10%; and the coal ash to <span class="hlt">elemental</span> sulfur ratio, 10 : 1. After ten days of leaching, 52.0, 52.6, and 59.5% of scandium, yttrium, and lanthanum, respectively, were recovered. PMID:26263628</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAfES..90...64A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES..90...64A"><span id="translatedtitle">The provenance of Cretaceous to Quaternary sediments in the Tarfaya basin, SW Morocco: Evidence from trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and radiogenic Nd-Sr isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ali, Sajid; Stattegger, Karl; Garbe-Schönberg, Dieter; Frank, Martin; Kraft, Steffanie; Kuhnt, Wolfgang</p> <p>2014-02-01</p> <p>We present trace <span class="hlt">element</span> compositions, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and radiogenic Nd-Sr isotope analyses of Cretaceous to recent sediments of the Tarfaya basin, SW Morocco, in order to identify tectonic setting, source rocks composition and sediments provenance. The results suggest that the sediments originate from heterogeneous source areas of the Reguibat Shield and the Mauritanides (West African Craton), as well as the western Anti-Atlas, which probably form the basement in this area. For interpreting the analyzed trace <span class="hlt">element</span> results, we assume that <span class="hlt">elemental</span> ratios such as La/Sc, Th/Sc, Cr/Th, Th/Co, La/Co and Eu/Eu? in the detrital silicate fraction of the sedimentary rocks behaved as a closed system during transport and cementation, which is justified by the consistency of all obtained results. The La/Y-Sc/Cr binary and La-Th-Sc ternary relationships suggest that the Tarfaya basin sediments were deposited in a passive margin setting. The trace <span class="hlt">element</span> ratios of La/Sc, Th/Sc, Cr/Th and Th/Co indicate a felsic source. Moreover, chondrite-normalized REE patterns with light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE) enrichment, a flat heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> (HREE) and negative Eu anomalies can also be attributed to a felsic source for the Tarfaya basin sediments. The Nd isotope model ages (TDM = 2.0-2.2 Ga) of the Early Cretaceous sediments suggest that sediments were derived from the Eburnean terrain (Reguibat Shield). On the other hand, Late Cretaceous to Miocene--Pliocene sediments show younger model ages (TDM = 1.8 Ga, on average) indicating an origin from both the Reguibat Shield and the western Anti-Atlas. In contrast, the southernmost studied Sebkha Aridal section (Oligocene to Miocene-Pliocene) yields older provenance ages (TDM = 2.5-2.6 Ga) indicating that these sediments were dominantly derived from the Archean terrain of the Reguibat Shield.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21222359','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21222359"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Jurassic coals in the Feke and Kozan (Adana) Areas, Eastern Taurides, Turkey</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kara-Gulbay, R.; Korkmaz, S.</p> <p>2009-07-01</p> <p>In this study, trace <span class="hlt">element</span> and organic matter-trace <span class="hlt">element</span> relation between Jurassic coals exposed in three different fields in the eastern Taurides were examined and their enrichment values with respect to upper crust values were calculated and the coal characteristics were also compared with world arithmetic means and those from the U.S. In comparison to the Feke and Kizilin coals, Pb, Zn, Ag, and Hg <span class="hlt">element</span> contents of the Gedikli coals are considerably high; Ni, As, and Ge contents are moderately high; and Cr, Cu, Co, Cd, Sb, Ga, and Sn contents are slightly high. The <span class="hlt">element</span> concentrations are very similar to those of other fields. In the Gedikli coals, Sr content is extremely low and Ba content is slightly low with respect to other fields. Re, Mo, U, V, and B <span class="hlt">element</span> concentrations are different for each of three fields. The major <span class="hlt">element</span> contents of the Feke, Gedikli, and Kizilin coals were correlated with world arithmetic means and average values of coals from the U.S. and Fe, K, Mg, and Na concentrations were found to be similar. Ti and Al contents of the world and USA coals are higher while Ca and Mn concentrations are lower. Considering trace <span class="hlt">element</span> contents of the world and U.S. coals, Ba is considerably high, Cu and Zr are moderately high, and Ga, Rb, and Sc <span class="hlt">elements</span> are slightly high. In comparison to world arithmetic means and U.S. coals, Sr content of the Feke and Kizilin coals are very high while those of the Gedikli coals are lower. For major and trace <span class="hlt">elements</span>, factors of enrichment with respect to upper crust values were also calculated. The highest enrichment values were calculated for Ca and S. Except for Se and Rb, all other trace <span class="hlt">elements</span> are enriched with respect to upper crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750003762&hterms=FERTILITY&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DFERTILITY','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750003762&hterms=FERTILITY&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DFERTILITY"><span id="translatedtitle">Determination of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in Luna 16 regolith sample by chemical spectral method</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stroganova, N. S.; Ryabukhin, V. A.; Laktinova, N. V.; Ageyeva, L. V.; Galkina, I. P.; Gatinskaya, N. G.; Yermakov, A. N.; Karyakin, A. V.</p> <p>1974-01-01</p> <p>An analysis was made of regolith from layer A of the Luna 16 sample for rare <span class="hlt">earth</span> <span class="hlt">elements</span>, by a chemical spectral method. Chemical and ion exchange concentrations were used to determine the content of 12 <span class="hlt">elements</span> and Y at the level 0.001 to 0.0001 percent with 10 to 15 percent reproducibility of the emission determination. Results within the limits of reproducibility agree with data obtained by mass spectra, activation, and X-ray fluorescent methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Litho.177..297L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Litho.177..297L"><span id="translatedtitle">Petrology, major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span>, geochronology, and isotopic composition of granitic intrusions from the vicinity of the Bosumtwi impact crater, Ghana</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Losiak, Anna; Schulz, Toni; Buchwaldt, Robert; Koeberl, Christian</p> <p>2013-09-01</p> <p>The Bosumtwi crater is 10.5 km in diameter, 1.07 Ma old, well preserved impact structure located in Ghana (centered at 06°30?N, 01°25?W). It was excavated in rocks of the Early Proterozoic Birimian Supergroup, part of the West African craton. Here, we present a full and detailed characterization of the three granitoid complexes and one mafic dike in the vicinity of the Bosumtwi crater in terms of petrology, major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span>, geochronology, and isotopic composition. This allows us to characterize magmatic evolution of the West African Craton in this area and better understand the geological framework and target rocks of the impact. This study shows that the similar composition (strongly peraluminous muscovite granites and granodiorites) and age (between 2092 ± 6 Ma and 2098 ± 6 Ma) of all granitic intrusions in the proximity of the Bosumtwi crater suggest that they are co-genetic. Granitoids were probably formed as a result of anatexis of TTGs (or rocks derived from them) at relatively low pressure and temperature. We propose that the intrusions from the Bosumtwi area are genetically related to the Banso granite occurring to the east of the crater and can be classified as basin-type, late-stage granitoids. Also a mafic dike located to the NE of the Bosumtwi crater seems to be genetically related to those felsic intrusions. Based on those findings a revised version of the geological map of the Bosumtwi crater area is proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23811462','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23811462"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of Manilkara zapota (L.) P. Royen, fruit from winder, Balochistan, Pakistan in perspective of medical geology.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hamza, Salma; Naseem, Shahid; Bashir, Erum; Rizwani, Ghazala H; Hina, Bushra</p> <p>2013-07-01</p> <p>An integrated study of rocks, soils and fruits of Manilkara zapota (L.) (Sapotaceae) of Winder area have been carried out to elaborate trace <span class="hlt">elements</span> relationship between them. The igneous rocks of the study area have elevated amount of certain trace <span class="hlt">elements</span>, upon weathering these <span class="hlt">elements</span> are concentrated in the soil of the area. The trace <span class="hlt">elements</span> concentration in the soil were found in the range of 0.8-197 for Fe, 1.23-140 for Mn, 0.03-16.7 for Zn, 0.07-9.8 for Cr, 0.05-2.0 for Co, 0.52-13.3 for Ni, 0.03-8.8 for Cu, 0.08-10.55 for Pb and 0.13-1.8?g/g for Cd. The distribution pattern of <span class="hlt">elements</span> in the rocks and soils reflected genetic affiliation. Promising <span class="hlt">elements</span> of edible part of the fruit were Fe (14.17), Mn (1.49), Cr (2.96), Ni (1.13), Co (0.92), Cu (1.70) and Zn (1.02?g/g). The concentration of these <span class="hlt">elements</span> in the fruits is above the optimum level of recommended dietary intake, probably due to this, disorder in the human health is suspected in the inhabitants of the area. PMID:23811462</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAfES.100..675A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES.100..675A"><span id="translatedtitle">Trace <span class="hlt">elements</span> <span class="hlt">geochemistry</span> of kerogen in Upper Cretaceous sediments, Chad (Bornu) Basin, northeastern Nigeria: Origin and paleo-redox conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adegoke, Adebanji Kayode; Abdullah, Wan Hasiah; Hakimi, Mohammed Hail; Sarki Yandoka, Babangida M.; Mustapha, Khairul Azlan; Aturamu, Adeyinka Oluyemi</p> <p>2014-12-01</p> <p>Trace <span class="hlt">element</span> contents in isolated kerogen from Upper Cretaceous sediments within Gongila and Fika formations in the Chad (Bornu) Basin, northeastern Nigeria were determined using Inductively-coupled plasma mass spectrometer (ICP-MS), in order to infer the origin of the organic matter and the paleo-redox conditions during their sedimentation. The concentrations of the <span class="hlt">elements</span> in the kerogen samples varied from 1.01 to 24,740 ppm. The distribution of <span class="hlt">elements</span> shows that Fe is the most abundant <span class="hlt">element</span> in Chad (Bornu) Basin kerogen, followed by Ce. Among the biophile <span class="hlt">elements</span>, V is the most abundant, followed by Ni and Co in that order. Statistical evaluation of the <span class="hlt">elemental</span> composition data shows that As, Ce, Pb, V, Cr, Fe, Co, Ni and U exhibit good positive correlations with each other. Molybdenum, on the other hand displays no obvious correlation with most of the trace <span class="hlt">elements</span> determined including TOC, but has good positive correlation with TS and negative correlation with Tmax, Ce and Th, which suggests that the concentration of Mo decreases with increasing maturity and vice versa. Some trace <span class="hlt">element</span> concentrations and their ratios suggest mixed marine and terrigenous source input for the organic matter (kerogen) in Chad (Bornu) Basin. More so, the concentrations of redox-sensitive <span class="hlt">elements</span>, such as V, Ni, Cu, Cr Mo and Mn, in the kerogen samples suggest dysoxic bottom water conditions within the Gongila and Fika sediments. Cross-plots of V and Ni and V/(V + Ni) ratio also indicate that the organic matter of these samples was deposited in slightly reducing environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19090098','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19090098"><span id="translatedtitle">Contribution to the <span class="hlt">geochemistry</span> of trace <span class="hlt">elements</span> in the sediments of the Noun River and tributaries, western Cameroon.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Njofang, C; Matschullat, J; Tchouankoué, J P; Amougou, A</p> <p>2007-09-15</p> <p>This study reports on the distribution of trace <span class="hlt">elements</span> in the sediments of the Noun River valley. Two groups of trace <span class="hlt">elements</span> have emerged based on their distribution and geochemical behaviour. The first group shows lower values whereas the second group aligns higher values. <span class="hlt">Elements</span> like Al and Sr in one side and Zn, Zr in the other present concentrations statistically different from those of the rocks compared to other <span class="hlt">elements</span> in trace analyzed (Cr, Ni, Ba, Co, Cu, Fe, Mn, V, As and Pb). The trace <span class="hlt">elements</span> Al, Sr, Zr, Zn and Pb in the sediments of the Noun River show concentrations rather lower than those of the world. The average concentrations in <span class="hlt">elements</span> C (3.72%), N (0.27%), S (0.05%) and of the ratios C/N (13.77) and N/S (5.29) reflect those resulting from the decomposition of the organic matter which derives from soils with very small concentrations in S. The Noun valley sediments are mostly of primary (quartz, microcline, plagioclase, orthoclase, ilmenite, anatase) and newly formed or secondary (kaolinite, gibbsite, hematite, goethite) minerals. This mineralogy and the overall low concentration of the studied trace <span class="hlt">elements</span>, with Al, Fe, Ti and Mn as most abundant <span class="hlt">elements</span>, is consistent with the local geology made up of the basic rocks (basalts, volcanic ash) and of the acid rocks (granites, gneiss). Overall the trace <span class="hlt">elements</span> concentration and distribution suggest their geogene origin. Yet, this study is a first contribution of its kind towards the development of a baseline geochemical database essential for a sustainable and healthier Noun valley ecosystem. PMID:19090098</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=geochemistry&id=EJ327326','ERIC'); return false;" href="http://eric.ed.gov/?q=geochemistry&id=EJ327326"><span id="translatedtitle"><span class="hlt">Geochemistry</span> for Chemists.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Hostettler, John D.</p> <p>1985-01-01</p> <p>A <span class="hlt">geochemistry</span> course for chemists is described. Includes: (1) general course information; (2) subject matter covered; and (3) a consideration of the uses of <span class="hlt">geochemistry</span> in a chemistry curriculum, including geochemical "real world" examples, <span class="hlt">geochemistry</span> in general chemistry, and <span class="hlt">geochemistry</span> as an elective. (JN)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810057588&hterms=nodule&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dnodule','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810057588&hterms=nodule&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dnodule"><span id="translatedtitle">Composition of the <span class="hlt">earth</span>'s upper mantle. I - Siderophile trace <span class="hlt">elements</span> in ultramafic nodules</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morgan, J. W.; Wandless, G. A.; Petrie, R. K.; Irving, A. J.</p> <p>1981-01-01</p> <p>The considered investigation is concerned with a reexamination of the question of the distribution of siderophile <span class="hlt">elements</span> in the <span class="hlt">earth</span>'s upper mantle, taking into account a more unified data base which is now available. A comprehensive suite of ultramafic inclusions was collected as part of the Basaltic Volcanism Study Project and has been analyzed by instrument neutron activation analysis for major, minor, and some lithophile trace <span class="hlt">elements</span>. In addition, 18 of these rocks and the important sheared garnet lherzolite PHN 1611 have been analyzed by means of radiochemical neutron activation analysis for 7 siderophile <span class="hlt">elements</span> (Au, Ge, Ir, Ni, Os, Pd, and Re) and 9 volatile <span class="hlt">elements</span> (Ag, Bi, Cd, In, Sb, Se, Te, Tl, and Zn). The siderophile <span class="hlt">element</span> data reveal interesting inter-<span class="hlt">element</span> correlations, which were not apparent from the compiled abundance tables of Ringwood and Kesson (1976) and Chou (1978).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20076087','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20076087"><span id="translatedtitle">Radioluminescence and thermoluminescence of rare <span class="hlt">earth</span> <span class="hlt">element</span> and phosphorus-doped zircon</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Karali, T.; Can, N.; Townsend, P.D.; Rowlands, A.P.; Hanchar, J.M.</p> <p>2000-06-01</p> <p>The radioluminescence and thermoluminescence spectra of synthetic zircon crystals doped with individual trivalent rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) ions (Pr, Sm, Eu, Gd, Dy, Ho, Er, and Yb) and P are reported in the temperature range 25 to 673 K. Although there is some intrinsic UV/blue emission from the host lattice, the dominant signals are from the rare-<span class="hlt">earth</span> sites, with signals characteristic of the REE{sup 3+} states. The shapes of the glow curves are different for each dopant, and there are distinct differences between glow peak temperatures for different rare-<span class="hlt">earth</span> lines of the same <span class="hlt">element</span>. Within the overall set of signals there are indications of linear trends in which some glow peak temperatures vary as a function of the ionic size of the rare <span class="hlt">earth</span> ions. The temperature shifts of the peaks are considerable, up to 200{degree}, and much larger than those cited in other rare-<span class="hlt">earth</span>-doped crystals of LaF{sub 3} and Bi{sub 4}Ge{sub 3}O{sub 12}. The data clearly suggest that the rare-<span class="hlt">earth</span> ions are active both in the trapping and luminescence steps, and hence the TL occurs within localized defect complexes that include REE{sup 3+} ions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.yale.edu/denglab/paper/PNAS-2014-Wang-1413376111.pdf','EPRINT'); return false;" href="http://www.yale.edu/denglab/paper/PNAS-2014-Wang-1413376111.pdf"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> activate endocytosis in plant cells Lihong Wanga,b,1</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Deng, Xing-Wang</p> <p></p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> activate endocytosis in plant cells Lihong Wanga,b,1 , Jigang Lic,d,1 , Qing on the plasma membrane in the form of nanoscale particles, and then entered the cells by endocytosis. Consistently, REEs activated endocytosis in plant cells, which may be the cellular basis of REE actions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=272377','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=272377"><span id="translatedtitle">Interactions between exogenous rare <span class="hlt">earth</span> <span class="hlt">elements</span> and phosphorus leaching in packed soil columns</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus (P) from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum (La), neodymium (Nd), samarium (Sm), and cerium (Ce), w...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=256482&keyword=earth&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=43028031&CFTOKEN=41140176','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=256482&keyword=earth&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=43028031&CFTOKEN=41140176"><span id="translatedtitle">A LOW-COST RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENTS</span> RECOVERY TECHNOLOGY - PHASE I</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><div> Physical Sciences, Inc., and the University of Kentucky Center for Applied Energy Research propose to develop a unique enabling technology to significantly reduce U.S. dependency for Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) on foreign suppliers and our global competitors. Our innovation...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47189&keyword=neutron&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=55013633&CFTOKEN=84469245','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47189&keyword=neutron&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=55013633&CFTOKEN=84469245"><span id="translatedtitle">SEDIMENT REWORKING AND TRANSPORT IN EASTERN LAKE SUPERIOR: IN SITU RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENT</span> TRACER STUDIES</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>A rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) tracer pellet was deployed at the floor of the Ile Parisienne basin of eastern Lake Superior to measure representative sediment reworking and transport processes in the benthic boundary layer of the prnfundal Great Lakes. Samarium oxide, a high neutron-...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=234552','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=234552"><span id="translatedtitle">Tracing sediment movement on semi-arid watershed using Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> 1988</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>A multi-tracer method employing rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) was used to determine sediment yield and to track sediment movement in a small semiarid watershed. A 0.33 ha watershed near Tombstone, AZ was divided into five morphological units, each tagged with one of five REE oxides. Relative contributi...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=250918','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=250918"><span id="translatedtitle">Preliminary study on using rare <span class="hlt">earth</span> <span class="hlt">elements</span> to trace non-point source phosphorous loss</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The environmental fate of phosphorus (P) is of concern as P is a primary cause of freshwater eutrophication. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have been successfully used in the analysis of soil erosion and pollutant sources, as well as in the analysis of mineral genesis. To better understand the potential...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP12B..07E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP12B..07E"><span id="translatedtitle">Provenance of glacial tills in Ong Valley, Antarctica, inferred from quartz cathodoluminescence imaging, zircon U/Pb dating, and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Edwards, K. L.; Padilla, A. J.; Evans, A.; Morgan, D. J.; Balco, G.; Putkonen, J.; Bibby, T.</p> <p>2014-12-01</p> <p>An issue for interpreting exposure ages using cosmogenic nuclides is prior exposure (inheritance), especially for stable nuclides such as Ne-21. In this study we examine the reliability of provenance as a possible tool for determining the degree to which inheritance is an issue for a given sample. We use zircon U/Pb ages, quartz cathodoluminescence imaging, and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> from Antarctic glacial drifts and compare these to zircon, quartz, and trace <span class="hlt">elements</span> from local bedrock in order to determine the drifts' origins. This is potentially useful in Ong Valley in the Central Transantarctic Mountains, and likely elsewhere in Antarctica, as Antarctic glacial sediments are only derived either from sources that lie beneath the ice, where it likely had little prior exposure to cosmic rays, or from the relatively small amount of local, exposed bedrock, which would have inherited nuclides. Thus, sediment provenance is likely correlated with its inherited nuclide inventory. The bedrock of Ong Valley is composed of granite (Hope Granite, Granite Harbour Intrusives) and gneiss, and contains three glacial drifts. We collected samples from these three drifts and the surrounding bedrock. Cosmogenic nuclide dating using Ne-21 provides exposure ages for the quartz that can be used to constrain the timing of the glacier's retreat from the three sites. The accuracy of these three exposure ages depends on the prior (or inherited) exposure of the sediment and its sources. The use of the use of multiple methods for determining provenance allows us to compare the results and see if they reach the same conclusion. If cathodoluminescence imaging proves to be a reliable method for establishing provenance it would provide complementary information for cosmogenic nuclide dating, especially because quartz is significantly more abundant and we would be obtaining coupled provenance information and exposure ages from a single mineral.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.135..217R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.135..217R"><span id="translatedtitle">Dripwater organic matter and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> in a semi-arid karst environment: Implications for speleothem paleoclimatology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rutlidge, Helen; Baker, Andy; Marjo, Christopher E.; Andersen, Martin S.; Graham, Peter W.; Cuthbert, Mark O.; Rau, Gabriel C.; Roshan, Hamid; Markowska, Monika; Mariethoz, Gregoire; Jex, Catherine N.</p> <p>2014-06-01</p> <p>A series of four short-term infiltration experiments which revealed hydrochemical responses relevant to semi-arid karst environments were carried out above Cathedral Cave, Wellington, New South Wales (NSW), Australia. Dripwater samples were collected at two sites for trace <span class="hlt">element</span> and organic matter analysis. Organic matter was characterised using fluorescence and interpreted using a PARAFAC model. Three components were isolated that represented unprocessed, soil-derived humic-like and fulvic-like material, processed humic/fulvic-like material and tryptophan-like fluorescence. Principal Component Analysis (PCA) performed on the entire dataset comprising trace <span class="hlt">element</span> concentrations and PARAFAC scores revealed two dominant components that were identified as soil and limestone bedrock. The soil component was assigned based on significant contributions from the PARAFAC scores and additionally included Ba, Cu, Ni and Mg. The bedrock component included the expected <span class="hlt">elements</span> of Ca, Mg and Sr as well as Si. The same <span class="hlt">elemental</span> behaviour was observed in recent stalagmite growth collected from the site. Our experiments demonstrate that existing paleoclimate interpretations of speleothem Mg and Sr, developed in regions of positive water balance, are not readily applicable to water limited environments. We provide a new interpretation of trace <span class="hlt">element</span> signatures unique to speleothems from water limited karst environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22280491','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22280491"><span id="translatedtitle">?-decay of neutron-rich Z?60 nuclei and the origin of rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wu, J.; Nishimura, S.; Lorusso, G.; Baba, H.; Doornenbal, P.; Isobe, T.; Söderström, P. A.; Sakurai, H.; Xu, Z. Y.; Browne, F.; Daido, R.; Fang, Y. F.; Yagi, A.; Nishibata, H.; Odahara, A.; Yamamoto, T.; Ideguchi, E.; Aoi, N.; Tanaka, M.; Collaboration: EURICA Collaboration; and others</p> <p>2014-05-02</p> <p>A large fraction of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> observed in the solar system is produced in the astrophysical rapid neutron capture process (r-process). However, current stellar models cannot completely explain the relative abundance of these <span class="hlt">elements</span> partially because of nuclear physics uncertainties. To address this problem, a ?-decay spectroscopy experiment was performed at RI Beam Factory (RIBF) at RIKEN, aimed at studying a wide range of very neutron-rich nuclei with Z?60 that are progenitors of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> with mass number A?460. The experiment provides a test of nuclear models as well as experimental inputs for r-process calculations. This contribution presents the experimental setup and some preliminary results of the experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/10376325','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/10376325"><span id="translatedtitle">Heavy metals and rare <span class="hlt">earth</span> <span class="hlt">elements</span> source-sink in some Egyptian cigarettes as determined by neutron activation analysis.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nada, A; Abdel-Wahab, M; Sroor, A; Abdel-Haleem, A S; Abdel-Sabour, M F</p> <p>1999-07-01</p> <p>Heavy metals and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in two types of cigarettes were studied. The contents of trace <span class="hlt">elements</span> were determined by using delayed neutron activation analysis. In the present study 11 <span class="hlt">elements</span> have been detected in popular and fine brand cigarettes marketed in Egypt. Evaluation of these <span class="hlt">elements</span> with their potential hazards for smokers is briefly discussed. The material balance (source and sink) for each <span class="hlt">element</span> was determined. Also the ratio of <span class="hlt">element</span> recovery to the total amount was assessed. PMID:10376325</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.geotop.ca/pdf/Gestion_Documents/Memoires/Memoire_Emma_Sheard.pdf','EPRINT'); return false;" href="http://www.geotop.ca/pdf/Gestion_Documents/Memoires/Memoire_Emma_Sheard.pdf"><span id="translatedtitle">Behaviour of zirconium, niobium, yttrium and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Thor Lake rare-metal</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p></p> <p></p> <p>Behaviour of zirconium, niobium, yttrium and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Thor Lake rare-metal © Emma Rebecca Sheard, 2010 #12;i ABSTRACT The Thor Lake rare-metal (Zr, Nb, Y, REE, Ta, Be, Ga) deposit and the heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the world. Much of the potentially economic mineralization was concentrated</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E6221Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E6221Z"><span id="translatedtitle">The Environmental <span class="hlt">Geochemistry</span> of Trace <span class="hlt">Elements</span> and Naturally Radionuclides in a Coal Gangue Brick-Making Plant</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Chuncai; Liu, Guijian; Cheng, Siwei; Fang, Ting; Lam, Paul K. S.</p> <p>2014-08-01</p> <p>An investigation focused on the transformation and distribution behaviors of trace <span class="hlt">elements</span> and natural radionuclides around a coal gangue brick plant was conducted. Simultaneous sampling of coal gangue, brick, fly ash and flue gas were implemented. Soil, soybean and earthworm samples around the brick plant were also collected for comprehensive ecological assessment. During the firing process, trace <span class="hlt">elements</span> were released and redistributed in the brick, fly ash and the flue gas. <span class="hlt">Elements</span> can be divided into two groups according to their releasing characteristics, high volatile <span class="hlt">elements</span> (release ratio higher than 30%) are represented by Cd, Cu, Hg, Pb, Se and Sn, which emitted mainly in flue gas that would travel and deposit at the northeast and southwest direction around the brick plant. Cadmium, Ni and Pb are bio-accumulated in the soybean grown on the study area, which indicates potential health impacts in case of human consumption. The high activity of natural radionuclides in the atmosphere around the plant as well as in the made-up bricks will increase the health risk of respiratory system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25164252','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25164252"><span id="translatedtitle">The environmental <span class="hlt">geochemistry</span> of trace <span class="hlt">elements</span> and naturally radionuclides in a coal gangue brick-making plant.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Chuncai; Liu, Guijian; Cheng, Siwei; Fang, Ting; Lam, Paul K S</p> <p>2014-01-01</p> <p>An investigation focused on the transformation and distribution behaviors of trace <span class="hlt">elements</span> and natural radionuclides around a coal gangue brick plant was conducted. Simultaneous sampling of coal gangue, brick, fly ash and flue gas were implemented. Soil, soybean and earthworm samples around the brick plant were also collected for comprehensive ecological assessment. During the firing process, trace <span class="hlt">elements</span> were released and redistributed in the brick, fly ash and the flue gas. <span class="hlt">Elements</span> can be divided into two groups according to their releasing characteristics, high volatile <span class="hlt">elements</span> (release ratio higher than 30%) are represented by Cd, Cu, Hg, Pb, Se and Sn, which emitted mainly in flue gas that would travel and deposit at the northeast and southwest direction around the brick plant. Cadmium, Ni and Pb are bio-accumulated in the soybean grown on the study area, which indicates potential health impacts in case of human consumption. The high activity of natural radionuclides in the atmosphere around the plant as well as in the made-up bricks will increase the health risk of respiratory system. PMID:25164252</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100025482','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100025482"><span id="translatedtitle">In Situ Instrumentation for Sub-Surface Planetary <span class="hlt">Geochemistry</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bodnarik, J.; Evans, L.; Floyd, S.; Lim, L.; McClanahan, T.; Namkung, M.; Parsons, A.; Schweitzer, J.; Starr, R.; Trombka, J.</p> <p>2010-01-01</p> <p>Novel instrumentation is under development at NASA's Goddard Space Flight Center, building upon <span class="hlt">earth</span>-based techniques for hostile environments, to infer geochemical processes important to formation and evolution of solid bodies in our Solar System. A prototype instrument, the Pulsed Neutron Generator Gamma Ray and Neutron Detectors (PNG-GRAND), has a 14 MeV pulsed neutron generator coupled with gamma ray and neutron detectors to measure quantitative <span class="hlt">elemental</span> concentrations and bulk densities of a number of major, minor and trace <span class="hlt">elements</span> at or below the surfaces with approximately a meter-sized spatial resolution down to depths of about 50 cm without the need to drill. PNG-GRAND's in situ a meter-scale measurements and adaptability to a variety of extreme space environments will complement orbital kilometer-scale and in-situ millimeter scale <span class="hlt">elemental</span> and mineralogical measurements to provide a more complete picture of the <span class="hlt">geochemistry</span> of planets, moons, asteroids and comets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998EOSTr..79..356M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998EOSTr..79..356M"><span id="translatedtitle">Principles and Applications of <span class="hlt">Geochemistry</span>, 2nd Edition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marcantonio, Franco</p> <p></p> <p>Many academic geology departments do not include <span class="hlt">geochemistry</span> in their undergraduate core curriculums. The second edition of Principles and Applications of <span class="hlt">Geochemistry</span> demonstrates why this should change. Gunter Faure's book clearly shows the important role played by quantitative geochemical analysis in our understanding of <span class="hlt">Earth</span> processes, both natural and anthropogenic. Intended as an introductory inorganic <span class="hlt">geochemistry</span> text for senior undergraduates or first-year graduate students, the book makes even the most difficult concepts readily understandable. Beyond its lucid technical explanations, it also includes engaging discussions of the history of <span class="hlt">geochemistry</span> as a science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990JVGR...44..123C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990JVGR...44..123C"><span id="translatedtitle">The 2 Ga peraluminous magmatism of the Jacobina — Contendas Mirante Belt (Bahia) Brazil): Major and trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> and metallogenic potential</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuney, Michel; Sabaté, Pierre; Vidal, Philippe; Marinho, Moacyr M.; Conceiçao, Herbet</p> <p>1990-12-01</p> <p>The Jacobina — Contendas Mirante belt represents a Transamazonian (2 Ga), N-S, 500-km long, elongated orogenic domain in the central part of the São Francisco craton, Bahia state. Numerous syntectonic to post-tectonic peraluminous leucogranites were emplaced along the major structures of the belt. Their mineralogical and geochemical and some of their metallogenetic characteristics are very similar to their Hercynian and Himalayan equivalents. However, their average peraluminous index varies from one granitic pluton to another and biotite is, on average, slightly more magnesian in the Transamazonian leucogranites. Higher oxygen fugacity is indicated by the general occurrence of magnetite, the stability of allanite and sometimes epidote in most of the plutons and by biotite chemistry. The peraluminous magmatism of the Jacobina-Contendas Mirante belt results from crustal partial melting during a continental collision event at 2 Ga. Trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> implies variable source composition and/or melting conditions for the different granitic plutons and some different facies within the same plutonic unit. The scarcity of ilmenite, the general occurrence of magnetite, and the relatively low peraluminous index of some of these granites suggest that graphite-beating sediments are not a significantly source material. From their mineralogical and geochemical characteristics, acid meta-igneous rocks such as the Sete Voltas TTG suite of presumed Archaean age, seem to represent a suitable source for these granites. Sn, W, Li, F and Be enrichment of most Transamazonian leucogranites is much weaker than in the mineralized Variscan equivalents. The Caetano-Aliança and Riacho das Pedras granites represent the most specialized granitic bodies. Beryl (emerald), molybdenite and scheelite mineralizations are related to some of these granites which intrude ultrabasic formations: the Campo Formoso and the Carnaiba granites. In many of these granites, uranium content is comparable to values measured in mineralized Hercynian leucogranites. The occurrence of hexavalent uranium minerals, mineralization and episyenitic alteration are favourable criteria for finding Variscan-type uranium ore deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5630347','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5630347"><span id="translatedtitle">Separation of tervalent transplutonium and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> using for-tveks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zaitsev, B.N.; Korolev, V.A.; Korovin, Y.F.; Kuzovov, Y.I.; Kvasnitskii, I.B.; Popik, V.P.</p> <p>1986-03-01</p> <p>The authors study the distribution of curium, americium, and certain rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) between aqueous nitric acid solutions and FOR-tveks under static and dynamic conditions. It is shown that on introducing diethylenetriaminepentaacetic acid into the aqueous solution separation coefficients for the transplutonium <span class="hlt">elements</span> and REE can be obtained which are sufficiently high for practical use. A method is proposed for the group separation of REE and transplutonium <span class="hlt">elements</span> under dynamic conditions. On a column 22 cm high coefficients of approximately 500 are obtained for the purification of curium from cerium, more than 260 from neodymium, 250 from lanthanum, and 14 from europium and gadolinium. The possibility has been studied of separating palladium from transplutonium <span class="hlt">elements</span> and REE and isolating it as an individual product.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1008833','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1008833"><span id="translatedtitle">The effect of rare <span class="hlt">earth</span> <span class="hlt">elements</span> on the texture and formability of asymmetrically rolled magnesium sheet</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Alderman, Dr. Martyn; Cavin, Odis Burl; Davis, Dr. Bruce; Muralidharan, Govindarajan; Muth, Thomas R; Peter, William H; Randman, David; Watkins, Thomas R</p> <p>2011-01-01</p> <p>The lack of formability is a serious issue when considering magnesium alloys for various applications. Standard symmetric rolling introduces a strong basal texture that decreases the formability; however, asymmetric rolling has been put forward as a possible route to produce sheet with weaker texture and greater ductility. It has also been shown in recent work that weaker textures can be produced through the addition of rare <span class="hlt">earth</span> <span class="hlt">elements</span> to magnesium alloys. Therefore, this study has been carried out to investigate the effect of rare <span class="hlt">earth</span> additions on the texture changes during asymmetric rolling. Two alloys have been used, AZ31B and ZEK100. The effect that the rare <span class="hlt">earth</span> additions have on the texture of asymmetrically rolled sheet and the subsequent changes in formability will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MAR.H1166T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MAR.H1166T"><span id="translatedtitle">Accurate projected augmented wave (PAW) datasets for rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (RE=La-Lu)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Topsakal, Mehmet; Wentzcovitch, Renata</p> <p>2015-03-01</p> <p>We provide accurate projected augmented wave (PAW) datasets for rare-<span class="hlt">earth</span> (RE) <span class="hlt">elements</span> with some suggested Hubbard U values allowing efficient plane-wave calculations. Solid state tests of generated datasets were performed on rare-<span class="hlt">earth</span> nitrides. Through density of state (DOS) and equation of state (EoS) comparisons, generated datasets were shown to yield excellent results comparable to highly accurate all-electron full-potential linearized augmented plane-wave plus local orbital (FLAPW+LO) calculations. Hubbard U values for trivalent RE ions are determined according to hybrid functional calculations. We believe that these new and open-source PAW datasets will allow further studies on rare-<span class="hlt">earth</span> materials. NSF/EAR 1319361</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022811','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022811"><span id="translatedtitle">Major, trace <span class="hlt">element</span> and isotope <span class="hlt">geochemistry</span> (Sr-Nd-Pb) of interplinian magmas from Mt. Somma-Vesuvius (Southern Italy)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Somma, R.; Ayuso, R.A.; de Vivo, B.; Rolandi, G.</p> <p>2001-01-01</p> <p>Major, trace <span class="hlt">element</span> and isotopic (Sr, Nd, Pb) data are reported for representative samples of interplinian (Protohistoric, Ancient Historic and Medieval Formations) activity of Mt. Somma-Vesuvius volcano during the last 3500 years. Tephra and lavas exhibit significant major, trace <span class="hlt">element</span> and isotopic variations. Integration of these data with those obtained by previous studies on the older Somma suites and on the latest activity, allows to better trace a complete petrological and geochemical evolution of the Mt. Somma-Vesuvius magmatism. Three main groups of rocks are recognized. A first group is older than 12.000 yrs, and includes effusive-explosive activity of Mt. Somma. The second group (8000-2700 yrs B.P.) includes the products emitted by the Ottaviano (8000 yrs. B.P.) and Avellino (3550 yrs B.P.) plinian eruptions and the interplinian activity associated with the Protohistoric Formation. Ancient Historic Formation (79-472 A.D.), Medieval Formation (472-1139 A.D.) and Recent interplinian activity (1631-1944 A.D.) belong to the third group of activity (79-1944 A.D.). The three groups of rocks display distinct positive trends of alkalis vs. silica, which become increasingly steeper with age. In the first group there is an increase in silica and alkalis with time, whereas an opposite tendency is observed in the two younger groups. Systematic variations are also evident among the incompatible (Pb, Zr, Hf, Ta, Th, U, Nb, Rb, Cs, Ba) and compatible <span class="hlt">elements</span> (Sr, Co, Cr). REE document variable degrees of fractionation, with recent activity displaying higher La/Yb ratios than Medieval and Ancient Historic products with the same degree of evolution. N-MORB normalized multi-<span class="hlt">element</span> diagrams for interplinian rocks show enrichment in Rb, Th, Nb, Zr and Sm (> *10 N-MORB). Sr isotope ratios are variable, with Protohistoric rocks displaying 87Sr/86Sr= 0.70711-0.70810, Ancient Historic 87Sr/86Sr=0.70665-0.70729, and Medieval 87Sr/86Sr=0.70685-0.70803. Neodymium isotopic compositions in the interplinian rocks show a tendency to become slightly more radiogenic with age, from the Protohistoric (143Nd/144Nd=0.51240-0.51247) to Ancient Historic (143Nd/144Nd=0.51245-0.51251). Medieval interplinian activity (143Nd/144Nd: 0.51250-0.51241) lacks meaningful internal trends. All the interplinian rocks have virtually homogeneous compositions of 207Pb/204Pb and 208Pb/204Pb in acid-leached residues (207Pb/204Pb ???15.633 to 15.687, 208Pb/204Pb ???38.947 to 39.181). Values of 206Pb/204Pb are very distinctive, however, and discriminate among the three interplinian cycles of activity (Protohistoric: 18.929-18.971, Ancient Historic: 19.018-19.088, Medieval: 18.964-19.053). Compositional trends of major, trace <span class="hlt">element</span> and isotopic compositions clearly demonstrate strong temporal variations of the magma types feeding the Somma-Vesuvius activity. These different trends are unlikely to be related only to low pressure evolutionary processes, and reveal variations of parental melt composition. Geochemical data suggest a three component mixing scheme for the interplinian activity. These involve HIMU-type and DMM-type mantle and Calabrian-type lower crust. Interaction between these components has taken place in the source; however, additional quantitative constraints must be acquired in order to better discriminate between magma characteristics inherited from the sources and those acquired during shallow level evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20019001','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20019001"><span id="translatedtitle">Extraction of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> from nitric solutions by phosphoryl-containing podands</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Turanov, A.N.; Karandashev, V.K.; Baulin, V.E.</p> <p>1999-11-01</p> <p>The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO{sub 3} solutions by phosphoryl-containing podands of various structures has been studied.. It has been found that the maximum extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> is exhibited by reagents containing one ether oxygen atom in the molecule, bound to diphenylphosphoryl or ditolylphosphoryl groups by methylene and o-phenylene fragments. The structure of these reagents is best suited for the polydentate coordination of the ligand and the conditions of a chelate complex formation. The effect of HNO{sub 3} concentration in the aqueous phase and that of the nature of an organic diluent on the extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and Y are considered. Stoichiometric of the extracted complexes has been determined and the extraction constants calculated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21541284','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21541284"><span id="translatedtitle">Symmetric charge-transfer cross sections of IIIa rare-<span class="hlt">earth</span>-metal <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hashida, Masaki; Sakabe, Shuji; Izawa, Yasukazu</p> <p>2011-03-15</p> <p>Symmetric charge-transfer cross sections of IIIa rare-<span class="hlt">earth</span>-metal <span class="hlt">elements</span> (Sc, Y, and Gd) in the impact energy range of 30 to 1000 eV were measured for the first time. The experiments were performed with a crossed-beam apparatus that featured primary ion production by photoionization with a tunable dye laser. Comparing the cross sections of IIIa rare-<span class="hlt">earth</span>-metal <span class="hlt">elements</span> ({sigma}{sub Sc}, {sigma}{sub Y}, and {sigma}{sub Gd}) with those of alkali metals or helium {sigma}{sub 0}, we found that {sigma}{sub 0{approx_equal}{sigma}Sc}<{sigma}{sub Y}<{sigma}{sub Gd{approx_equal}}2{sigma}{sub 0}at an impact energy of 1000 eV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17837193','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17837193"><span id="translatedtitle">Bishop tuff revisited: new rare <span class="hlt">Earth</span> <span class="hlt">element</span> data consistent with crystal fractionation.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cameron, K L</p> <p>1984-06-22</p> <p>The Bishop Tuff of eastern California is the type example of a high-silica rhyolite that, according to Hildreth, supposedly evolved by liquid-state differentiation. New analyses establish that the Bishop Tuff "earlyllate" rare <span class="hlt">earth</span> <span class="hlt">element</span> trend reported by Hildreth mimics the relations between groundmass glasses and whole rocks for allanite-bearing pumice. Differences in <span class="hlt">elemental</span> concentrations between whole rock and groundmass are the result of phenocryst precipitation; thus the data of Hildreth are precisely those expected to result from crystal fractionation. PMID:17837193</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985GeCoA..49.1875W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985GeCoA..49.1875W"><span id="translatedtitle">Isotope and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of sediments from the Barbados Ridge-Demerara Plain region, Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>White, William M.; Dupré, Bernard; Vidal, Philippe</p> <p>1985-09-01</p> <p>Twenty-four piston core sediment samples and 13 sediments and 3 basalts from DSDP Leg 78 Site 543 were analyzed for Sr, Nd and Pb isotopic compositions. The results show sediment with highly radiogenic Pb 206Pb /204Pb up to 19.8) and rather radiogenic Sr and unradiogenic Nd has been deposited in the region since the Cretaceous. The source of this sediment is probably the Archean Guiana Highland, which is drained by the Orinoco River. Pb and Sr isotopic compositions and sediment thickness decrease and 143Nd /144Nd increases northward due to a decrease in turbiditic component. This decrease is partly due to the damming action of basement ridges. Rare <span class="hlt">earth</span> concentrations in the sediments are somewhat low, due to the abundance of detrital and biogenic components in the sediment and rapid sedimentation rates. Both positive and negative Ce anomalies occur in the surface sediments, but only positive Ce anomalies occur in the Site 543 sediments. It is unlikely that sediment subducted to the source region of Lesser Antilles arc magmas could be the cause of negative Ce anomalies in those magmas. Isotopic compositions of Site 543 basalts show some effect of contamination by seawater-basalt reaction products and sediments. Beyond this, however, they are typical of "normal" depleted MORB.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAESc..95..228C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAESc..95..228C"><span id="translatedtitle">Petrogenesis of Late Permian sodic metagranitoids in southeastern Korea: SHRIMP zircon geochronology and <span class="hlt">elemental</span> and Nd-Hf isotope <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cheong, Chang-sik; Kim, Namhoon; Kim, Jeongmin; Yi, Keewook; Jeong, Youn-Joong; Park, Chan-Soo; Li, Huai-kun; Cho, Moonsup</p> <p>2014-12-01</p> <p>One of the striking tectonomagmatic features recently found in southeastern Korea is the occurrence of ca. 250 Ma high-silica adakite. Sodic metagranitoids mainly consisting of tonalitic-trondhjemitic-granodioritic gneisses occur in the Andong-Cheongsong area adjacent to the Yeongdeok adakite site. To investigate temporal and petrogenetic relationships of these orthogneisses with the adakite, we conducted SHRIMP zircon U-Pb dating as well as <span class="hlt">elemental</span> and Nd-Hf isotopic analyses. Zircon core ages of the orthogneisses (ca. 262-251 Ma) confirm the widespread occurrence of arc-related Late Permian magmatism in southeastern Korea. The Late Triassic (ca. 230 Ma) zircon overgrowths reflect a thermal overprint probably related to the initiation of another subduction system. The analyzed orthogneisses have major <span class="hlt">element</span> compositions comparable to the Phanerozoic adakites and Archean TTG suite, such as high SiO2 (58.7-65.5 wt.%) and Al2O3 (17.1-19.1 wt.%) contents and Na2O/K2O ratios (1.83-4.95). However, their moderate Sr/Y (35-43) and La/Yb (14-53) ratios and negative Eu anomalies (Eu/Eu* = 0.75-0.95) are incompatible with the key features reported from the Yeongdeok adakite. Moreover, initial whole-rock ?Nd (-7.9 to -3.3) and zircon ?Hf (-0.3 ± 2.4) values of the orthogneisses negate a direct derivation from the subducted slab. Our <span class="hlt">elemental</span> and Nd-Hf isotopic data collectively suggest that the protoliths of the tonalitic-trondhjemitic-granodioritic gneisses were generated by partial melting of mafic lower crust at depths shallower than the garnet stability field. Our Nd and Hf model ages of the gneisses, together with those previously reported from the Mesozoic granitoids indicate a selective involvement of young source materials along the margin of the Yeongnam massif. The Hf isotopic compositions of zircons from a trondhjemitic gneiss attest to the involvement of primitive melts during their crystallization. The ridge subduction and consequent development of a slab window may have facilitated partial melting of the subducted oceanic lithosphere and the lower crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23896401','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23896401"><span id="translatedtitle">Major and minor <span class="hlt">element</span> <span class="hlt">geochemistry</span> of deep-sea sediments in the Azores Platform and southern seamount region.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Palma, Carla; Oliveira, Anabela; Valença, Manuela; Cascalho, João; Pereira, Eduarda; Lillebø, Ana I; Duarte, Armando C; Pinto de Abreu, Manuel</p> <p>2013-10-15</p> <p>The Azores Platform and the Irving and Great Meteor seamounts south of the archipelago (38°N-29°N) have rarely been studied geochemically, a fact which is surprising given that they represent the south-eastern limit of region V outlined in the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention). The main aim of the present work was therefore to characterise the spatial variability of major and minor <span class="hlt">elements</span> in deep-sea sediment cores from these two regions. XRD and geochemical analyses revealed that whereas the Azores Platform sediments are composed of a mixture of biogenic and detrital volcanic material, those at the seamounts are characterised by carbonated biogenic remains. The latter sediments were found to contain very low amounts of volcanic or hydrothermal detrital material, being almost entirely comprised of CaCO3 (more than 80%). PMID:23896401</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11529577','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11529577"><span id="translatedtitle">Transport of rare <span class="hlt">earth</span> <span class="hlt">element</span>-tagged soil particles in response to thunderstorm runoff.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matisoff, G; Ketterer, M E; Wilson, C G; Layman, R; Whiting, P J</p> <p>2001-08-15</p> <p>The downslope transport of rare <span class="hlt">earth</span> <span class="hlt">element</span>-tagged soil particles remobilized during a spring thunderstorm was studied on both a natural prairie and an agricultural field in southwestern Iowa (U.S.A.). A technique was developed for tagging natural soils with the rare <span class="hlt">earth</span> <span class="hlt">elements</span> Eu, Tb, and Ho to approximately 1,000 ppm via coprecipitation with MnO2. Tagged material was replaced in target locations; surficial soil samples were collected following precipitation and runoff; and rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations were determined by inductively coupled plasma mass spectrometry. Diffusion and exponential models were applied to the concentration-distance data to determine particle transport distances. The results indicate that the concentration-distance data are well described by the diffusion model, butthe exponential model does not simulate the rapid drop-off in concentrations near the tagged source. Using the diffusion model, calculated particle transport distances at all hillside locations and at both the cultivated and natural prairie sites were short, ranging from 3 to 73 cm during this single runoff event. This study successfully demonstrates a new tool for studying soil erosion. PMID:11529577</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/191705','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/191705"><span id="translatedtitle">Ultra-trace rare <span class="hlt">earth</span> <span class="hlt">element</span> analysis of geochemical reference samples using a recycling nebulization system with a disposable spray chamber by inductively coupled plasma-mass spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chen, Z.; Fryer, B.J.; Longerich, H.P.</p> <p>1994-12-31</p> <p>In recent years, the precise and accurate determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in a range of rock types has became increasingly important. Interpretation of the REE <span class="hlt">geochemistry</span> of igneous and metamorphic rocks and minerals is a prerequisite for the development of many petrogenetic models. Inductively coupled plasma-mass spectrometry (ICP-MS) is a multi-<span class="hlt">element</span> analytical method having detection limits across the whole mass range which are superior to most conventional techniques, particularly for heavy <span class="hlt">elements</span>. However, there are samples in which the REE concentrations are below the detection limits (0.01-0.1 ppm) of whole rock procedures (1) in which samples are prepared at 0.5 g rock per kg solution (0.1 g per 200 g solution). A procedure, such as ion exchange, which increases the concentration of the REE`s while maintaining the total dissolved solids at less then 0.1% is required. In this study, 15 ultra-trace rare <span class="hlt">earth</span> <span class="hlt">elements</span> have been determined in 5 international geochemical reference samples at ultra-trace levels, PCC-1 (USGS), AL-I (GIT-IWG), FK-N (ANRT), NBS70a and NBS99a, using a recycling nebulization system with a disposable spray chamber by inductively coupled plasma-mass spectrometry (2), after preconcentrating the REEs from a 100 mg sample using cation exchange. Samples were dissolved, and a REE separate was obtained using 10 ml of cation exchange resin in a quartz column. Major <span class="hlt">elements</span> were eluted using a 1.13 M HNO{sub 3}-0.63 M HCI solution. The REE were collected using 8 M HNO{sub 3}. The solution containing the REE`s was evaporated to dryness, the residue dissolved in HNO{sub 3}, and diluted to a final weight of 2 g using 0.2 M HNO{sub 3}. Solid limits of detection are 0.01-1 ppb. Precision, accuracy and sample heterogeneity are addressed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.163..234D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.163..234D"><span id="translatedtitle">Thulium anomalies and rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns in meteorites and <span class="hlt">Earth</span>: Nebular fractionation and the nugget effect</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dauphas, Nicolas; Pourmand, Ali</p> <p>2015-08-01</p> <p>This study reports the bulk rare <span class="hlt">earth</span> <span class="hlt">element</span> (REEs, La-Lu) compositions of 41 chondrites, including 32 falls and 9 finds from carbonaceous (CI, CM, CO and CV), enstatite (EH and EL) and ordinary (H, L and LL) groups, as well as 2 enstatite achondrites (aubrite). The measurements were done in dynamic mode using multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS), allowing precise quantification of mono-isotopic REEs (Pr, Tb, Ho and Tm). The CI-chondrite-normalized REE patterns (LaN/LuN; a proxy for fractionation of light vs. heavy REEs) and Eu anomalies in ordinary and enstatite chondrites show more scatter in more metamorphosed (petrologic types 4-6) than in unequilibrated (types 1-3) chondrites. This is due to parent-body redistribution of the REEs in various carrier phases during metamorphism. A model is presented that predicts the dispersion of <span class="hlt">elemental</span> and isotopic ratios due to the nugget effect when the analyzed sample mass is limited and <span class="hlt">elements</span> are concentrated in minor grains. The dispersion in REE patterns of equilibrated ordinary chondrites is reproduced well by this model, considering that REEs are concentrated in 200 ?m-size phosphates, which have high LaN/LuN ratios and negative Eu anomalies. Terrestrial rocks and samples from ordinary and enstatite chondrites display negative Tm anomalies of ?-4.5% relative to CI chondrites. In contrast, CM, CO and CV (except Allende) show no significant Tm anomalies. Allende CV chondrite shows large excess Tm (?+10%). These anomalies are similar to those found in group II refractory inclusions in meteorites but of much smaller magnitude. 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 and carried positive Tm anomalies or (ii) CI chondrites are enriched in refractory dust and are not representative of solar composition for refractory <span class="hlt">elements</span>. A new reference composition relevant to inner solar system bodies (CI?) is calculated by subtracting 0.15% of group II refractory inclusions to CI. The observed Tm anomalies in ordinary and enstatite chondrites and terrestrial rocks, relative to carbonaceous chondrites, indicate that material akin to carbonaceous chondrites must have represented a small fraction of the constituents of the <span class="hlt">Earth</span>. Tm anomalies may be correlated with Ca isotopic fractionation in bulk planetary materials as they are both controlled by addition or removal of refractory material akin to fine-grained group II refractory inclusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/2003/0477/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2003/0477/"><span id="translatedtitle">A compilation of whole-rock and glass major-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of Kilauea Volcano, Hawai'i, near-vent eruptive products: January 1983 through September 2001</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Thornber, Carl R.; Hon, Ken; Heliker, Christina; Sherrod, David A.</p> <p>2003-01-01</p> <p>This report presents major-<span class="hlt">element</span> geochemical data from 652 glasses (~6,520 analyses) and 795 whole-rock aliquots from 1,002 fresh samples of olivine-tholeiitic lava collected throughout the near-continuous eruption of Kïlauea Volcano, Hawai'i, from January 1983 through September 2001. The data presented herein provide a unique temporal compilation of lava <span class="hlt">geochemistry</span> that best reflects variations of pre-eruptive magma compositions during prolonged rift-zone eruption. This document serves as a repository for geochemical data referred to in U.S. Geological Survey Professional Paper 1676 (Heliker, Swanson, and Takahashi, eds., 2003) which includes multidisciplinary research papers pertaining to the first twenty years of Puu Oo-Kupaianaha eruption activity. Details of eruption characteristics and nomenclature are provided in the introductory chapter of that volume (Heliker and Mattox, 2003). Geochemical relations among all or portions of this data set are depicted and interpreted by Thornber (2003), Thornber and others (2003) and Thornber (2001). Trace <span class="hlt">element</span> compositions and Nd, Sr and Pb isotopic analyses of representative samples of this select eruption suite will be provided in a separate and complimentary open file report. From 1983 to October 2001, approximately 2,500 eruption samples were collected and archived by the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO). Geochemical data for 1,002 of these samples are included here. Previous reports present bulk-lava major- <span class="hlt">element</span> chemistry for eruption samples collected from 1983 to 1986 and from 1990 to 1994 (Neal and others, 1988 and Mangan and others, 1995, respectively). Major <span class="hlt">element</span> glass chemistry and thermometry data for samples collected from 1983 to 1994 is reported by Helz and Hearn (1998) and whole-rock and glass chemistry for samples collected from September 1994 to October 2001 is provided by Thornber and others (2002). This report is a compilation of previously published data along with unpublished whole-rock data for the 1986–1990 eruptive interval (episode 48, see Heliker and Mattox, 2003). The geochemical data in this report is mostly limited to well-quenched samples collected at or near their respective vents. The samples include tephra and spatter, in addition to lava dipped from lava lakes, lava tubes, and surface lava flows. The details of sample collection techniques as described by Thornber and others (2002) are generally applicable for this entire sampling interval. Specifically excluded from this database are samples of distal surface flows, many of which were collected for topical studies of emplacement dynamics (for example, Cashman and others, 1999). Samples of sluggish or crystal-laden tube flows collected during eruptive pauses were also excluded, because they bear visual, petrographic and geochemical evidence for crystal accumulation during surface-flow stagnation. In addition, the pre-1992 whole-rock major <span class="hlt">element</span> data reported here has been corrected to compensate for minor analytical discrepancies between pre- and post-1991 XRF analyses. These discrepancies resulted from a change in instrumentation at the USGS Denver analytical laboratories. This select suite of time-constrained geochemical data is suitable for constructing petrologic models of pre-eruptive magmatic processes associated with prolong rift zone eruption of Hawaiian shield volcanoes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMPP13B2116G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMPP13B2116G"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of Snowball <span class="hlt">Earth</span> glacial tillites from China and North America: implications for the bulk composition of the Neoproterozoic upper crust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaschnig, R. M.; Rudnick, R. L.; McDonough, W. F.; Gao, S.; Hu, Z.; Zhou, L.</p> <p>2012-12-01</p> <p>In order to understand the differentiation of the <span class="hlt">Earth</span> and growth of continents through time, it is critical to have reliable estimates for the average composition of the continental crust. Attempts to develop average compositional models for the upper continental crust have often relied upon the analysis of sediments and sedimentary rocks, based on the assumption that these provide natural averages of large crustal areas. Shales are among the most frequently used proxies, although some workers have also studied loess. The advantage of loess, especially that which is derived from glacial processes, is that it is typically produced by physical weathering alone and should lack the <span class="hlt">elemental</span> fractionation produced by chemical weathering. Glacial tillites should also provide this advantage, and in addition, they should lack <span class="hlt">element</span> fractionation caused by eolian particle sorting that is observed in loess. Here, we present new major and trace <span class="hlt">element</span> data for glacial tillites from the Neoproterozoic, collected in southern China and the eastern U.S. Samples were collected from tillites of the Marinoan(?) Nantuo and Sturtian Gucheng Formations in Hubei Province, China (n = 21), and the Sturtian Konnarock Formation in the Appalachians of southwestern Virginia (n = 11). Values for the chemical index of alteration (Al2O3/Al2O3+K2O+Na2O+CaO) for these rocks are low, between 60 and 70 for most of the Chinese samples and 53 and 60 for all of the American ones, reflecting derivation from material that has experienced very little chemical weathering. The individual samples from the two localities show remarkable homogeneity, but their average compositions are distinct. The Chinese tillites match more closely the average upper crust composition of Rudnick and Gao (2003) than the Virginia ones, but the former still show a few major differences. Select soluble <span class="hlt">elements</span>, such as Sr, Tl, and U, are depleted by as great a factor as ten, whereas other soluble <span class="hlt">elements</span>, such as Li, Rb, and Cs, are either enriched or similar to the upper crustal model. By contrast, the Virginia tillites show major enrichment in the high field strength <span class="hlt">elements</span> and rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and depletion in the first row transition metals associated with mafic minerals (e.g., Ni, Cr, Sc, V). These tillites also show a stronger negative Eu anomaly. The difference between the Chinese and Virginia Neoproterozoic tillites likely reflects the different provenance of the Virginia samples, but in detail, the implications of this observation are unclear. The Virginia tillite chemistry is similar to local Neoproterozoic A-type granites in the Appalachians, but is also similar to the regionally extensive Grenvillian basement. This is an important distinction, as it goes to the question of whether or not the till represents the integration of a large area, as opposed to being primarily locally derived. In the case of the Chinese tillites, published detrital zircon and whole-rock Nd isotopic data suggests the provenance encompassed a large crustal area, strengthening their legitimacy as a proxy for the average upper crust.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMDI23B4293L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMDI23B4293L"><span id="translatedtitle">What Can Neutrinos Tell Us about Light <span class="hlt">Elements</span> in <span class="hlt">Earth</span>'s Core?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, J.; Dye, S.; Enomoto, S.</p> <p>2014-12-01</p> <p>The light <span class="hlt">element</span> composition of the <span class="hlt">Earth</span>'s core remains mysterious despite decades' of research. Without any direct samples, our knowledge of the core composition has relied on a diversity of constraints including the density and velocity profiles derived from seismic and geophysical observations, the composition models proposed on the basis of geochemical and cosmochemical measurements, the material properties determined by mineral physics investigations, and the thermal and dynamo requirements coming out of dynamic modeling. The leading candidates for the principal light <span class="hlt">element</span> include hydrogen, carbon, oxygen, sulfur and silicon, in the order of increasing atomic number. While each candidate stands out in some aspects and raises questions in others, none has been universally accepted as the dominant light <span class="hlt">element</span> in the core. The controversy arises partly because the properties and behavior of various iron-alloys at extreme pressure and temperature conditions have not been fully constrained. It is also conceivable that existing approaches will not produce unique solution, and therefore requires new strategies. Neutrino oscillation tomography has recently emerged as a promising technique to probe the composition of <span class="hlt">Earth</span>'s interior. Neutrinos are produced in the atmosphere by cosmic ray interactions. Atmospheric neutrinos pass through the <span class="hlt">Earth</span>'s mantle and core, with flavor oscillations being affected by the electron density of the medium along the trajectories. The unique sensitivity of the atmospheric neutrinos to electron density introduces a contrast between hydrogen, which has a higher electron density, and carbon, oxygen, sulfur, and silicon, which have lower and similar electron densities. With sufficient exposure to an appropriate energy range, atmospheric neutrino measurements may allow us to detect the presence of the core and measure its radius. Here we compare electron densities of candidate model compositions of <span class="hlt">Earth</span>'s core and estimate the exposure requirements for identifying the dominant light <span class="hlt">element</span> thorough neutrino oscillation tomography for both neutrino mass hierarchies. In particular, we will evaluate if any of the on-going and next-generation projects IceCube, PINGU, MICA, and HyperK can tell us about the light <span class="hlt">elements</span> in <span class="hlt">Earth</span>'s core.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/273576','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/273576"><span id="translatedtitle">Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in environmental materials by inductively coupled plasma mass spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Panday, V.K.; Hoppstock, K.; Becker, J.S.; Dietze, H.J.</p> <p>1996-09-01</p> <p>Despite the fact that rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) have found increasing use in modern technology only few data are available on their concentrations in biological and environmental samples. Inductively coupled plasma mass spectrometry (ICP-MS) has been employed to study the concentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in various environmental materials (e.g., pine needles, mussel tissue, apple leaves) available from National Institute of Standards and Technology (NIST), the Bureau of European Communities (BCR), and the German Environmental Specimens Bank. After the decomposition of the environmental samples with HNO{sub 3}, the REE (present mostly in the ng/g-range) were separated from the matrix and simultaneously preconcentrated using liquid-liquid extraction with bis(2-ethyl hexyl)-ortho-phosphoric acid (HDEHP) in toluene as a selective reagent at pH = 2 and subsequent back extraction of the <span class="hlt">elements</span> into the aqueous by 6M HNO{sub 3}. Recoveries of better 90% were obtained for almost all REE. A Perkin Elmer/Sciex ELAN 5000 ICP-MS and HR-ICP-MS <span class="hlt">ELEMENT</span> from Finnigan MAT were used for quantitative analysis (by external calibration and ID-ICP-MS) of REE. The results of determination of REE concentrations agree well with the data available on some of these materials. Further supplement information on the contents of various REE in these materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820048232&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820048232&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Complementary rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the <span class="hlt">earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ma, M.-S.; Schmitt, R. A.; Laul, J. C.</p> <p>1982-01-01</p> <p>Abundances of major, minor, and trace <span class="hlt">elements</span> are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare <span class="hlt">earth</span> <span class="hlt">element</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2584670','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2584670"><span id="translatedtitle">Toward understanding early <span class="hlt">Earth</span> evolution: Prescription for approach from terrestrial noble gas and light <span class="hlt">element</span> records in lunar soils</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A.; Miura, Yayoi N.</p> <p>2008-01-01</p> <p>Because of the almost total lack of geological record on the <span class="hlt">Earth</span>'s surface before 4 billion years ago, the history of the <span class="hlt">Earth</span> during this period is still enigmatic. Here we describe a practical approach to tackle the formidable problems caused by this lack. We propose that examinations of lunar soils for light <span class="hlt">elements</span> such as He, N, O, Ne, and Ar would shed a new light on this dark age in the <span class="hlt">Earth</span>'s history and resolve three of the most fundamental questions in <span class="hlt">earth</span> science: the onset time of the geomagnetic field, the appearance of an oxygen atmosphere, and the secular variation of an <span class="hlt">Earth</span>–Moon dynamical system. PMID:19001263</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23548400','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23548400"><span id="translatedtitle">Bioleaching of rare <span class="hlt">earth</span> and radioactive <span class="hlt">elements</span> from red mud using Penicillium tricolor RM-10.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qu, Yang; Lian, Bin</p> <p>2013-05-01</p> <p>The aim of this work is to investigate biological leaching of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and radioactive <span class="hlt">elements</span> from red mud, and to evaluate the radioactivity of the bioleached red mud used for construction materials. A filamentous, acid-producing fungi named RM-10, identified as Penicillium tricolor, is isolated from red mud. In our bioleaching experiments by using RM-10, a total concentration of 2% (w/v) red mud under one-step bioleaching process was generally found to give the maximum leaching ratios of the REEs and radioactive <span class="hlt">elements</span>. However, the highest extraction yields are achieved under two-step bioleaching process at 10% (w/v) pulp density. At pulp densities of 2% and 5% (w/v), red mud processed under both one- and two-step bioleaching can meet the radioactivity regulations in China. PMID:23548400</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790055121&hterms=scandium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dscandium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790055121&hterms=scandium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dscandium"><span id="translatedtitle">Experimental partitioning of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and scandium among armalcolite, ilmenite, olivine and mare basalt liquid</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Irving, A. J.; Merrill, R. B.; Singleton, D. E.</p> <p>1978-01-01</p> <p>An experimental study was carried out to measure partition coefficients for two rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (Sm and Tm) and Sc among armalcolite, ilmenite, olivine and liquid coexisting in a system modeled on high-Ti mare basalt 74275. This 'primitive' sample was chosen for study because its major and trace <span class="hlt">element</span> chemistry as well as its equilibrium phase relations at atmospheric pressure are known from previous studies. Beta-track analytical techniques were used so that partition coefficients could be measured in an environment whose bulk trace <span class="hlt">element</span> composition is similar to that of the natural basalt. Partition coefficients for Cr and Mn were determined in the same experiments by microprobe analysis. The only equilibrium partial melting model appears to be one in which ilmenite is initially present in the source region but is consumed by melting before segregation of the high-Ti mare basalt liquid from the residue.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AcSpe.114...65M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AcSpe.114...65M"><span id="translatedtitle">Quantification of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using laser-induced breakdown spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Madhavi; Martin, Rodger C.; Allman, Steve; Brice, Deanne; Wymore, Ann; Andre, Nicolas</p> <p>2015-12-01</p> <p>A study of the optical emission as a function of concentration of laser-ablated yttrium (Y) and of six rare <span class="hlt">earth</span> <span class="hlt">elements</span>, europium (Eu), gadolinium (Gd), lanthanum (La), praseodymium (Pr), neodymium (Nd), and samarium (Sm), has been evaluated using the laser-induced breakdown spectroscopy (LIBS) technique. Statistical methodology using multivariate analysis has been used to obtain the sampling errors, coefficient of regression, calibration, and cross-validation of measurements as they relate to the LIBS analysis in graphite-matrix pellets that were doped with <span class="hlt">elements</span> at several concentrations. Each <span class="hlt">element</span> (in oxide form) was mixed in the graphite matrix in percentages ranging from 1% to 50% by weight and the LIBS spectra obtained for each composition as well as for pure oxide samples. Finally, a single pellet was mixed with all the <span class="hlt">elements</span> in equal oxide masses to determine if we can identify the <span class="hlt">elemental</span> peaks in a mixed pellet. This dataset is relevant for future application to studies of fission product content and distribution in irradiated nuclear fuels. These results demonstrate that LIBS technique is inherently well suited for the future challenge of in situ analysis of nuclear materials. These studies also show that LIBS spectral analysis using statistical methodology can provide quantitative results and suggest an approach in future to the far more challenging multielemental analysis of ~ 20 primary <span class="hlt">elements</span> in high-burnup nuclear reactor fuel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24681591','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24681591"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> recycling from waste phosphor by dual hydrochloric acid dissolution.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A</p> <p>2014-05-15</p> <p>This paper is a comparative study of recycling rare <span class="hlt">earth</span> <span class="hlt">elements</span> from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare <span class="hlt">earth</span> phosphor (Y0.95Eu0.05)2O3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce0.67Tb0.33MgAl11O19) and the Blue phosphor (Ba0.9Eu0.1MgAl10O17) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications. PMID:24681591</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26198417','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26198417"><span id="translatedtitle">Geochemical fractions of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil around a mine tailing in Baotou, China.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Lingqing; Liang, Tao</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China's largest rare <span class="hlt">earth</span> mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65?×?10(4)?mg·kg(-1) with an average value of 4.67?×?10(3)?mg·kg(-1), which was significantly higher than the average value in China (181?mg·kg(-1)). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected <span class="hlt">elements</span> (La(N)/Yb(N), La(N)/Sm(N) and Gd(N)/Yb(N)). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind. PMID:26198417</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...512483W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...512483W"><span id="translatedtitle">Geochemical fractions of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil around a mine tailing in Baotou, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Lingqing; Liang, Tao</p> <p>2015-07-01</p> <p>Rare <span class="hlt">earth</span> mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China’s largest rare <span class="hlt">earth</span> mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65?×?104?mg·kg-1 with an average value of 4.67?×?103?mg·kg-1, which was significantly higher than the average value in China (181?mg·kg-1). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected <span class="hlt">elements</span> (LaN/YbN, LaN/SmN and GdN/YbN). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1196551','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1196551"><span id="translatedtitle">Spectral Analysis of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> using Laser-Induced Breakdown Spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Madhavi Z. Martin; Robert V. Fox; Andrzej W. Miziolek; Frank C. DeLucia, Jr.; Nicolas Andre</p> <p>2001-05-01</p> <p>There is growing interest in rapid analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare <span class="hlt">earth</span> magnets are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9482E..0GM','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9482E..0GM"><span id="translatedtitle">Spectral analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> using laser-induced breakdown spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Madhavi Z.; Fox, Robert V.; Miziolek, Andrzej W.; DeLucia, Frank C.; André, Nicolas</p> <p>2015-06-01</p> <p>There is growing interest in rapid analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare <span class="hlt">earth</span> magnets are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510494','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510494"><span id="translatedtitle">Geochemical fractions of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil around a mine tailing in Baotou, China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Lingqing; Liang, Tao</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China’s largest rare <span class="hlt">earth</span> mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65?×?104?mg·kg?1 with an average value of 4.67?×?103?mg·kg?1, which was significantly higher than the average value in China (181?mg·kg?1). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected <span class="hlt">elements</span> (LaN/YbN, LaN/SmN and GdN/YbN). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind. PMID:26198417</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://arxiv.org/pdf/0903.1623.pdf','EPRINT'); return false;" href="http://arxiv.org/pdf/0903.1623.pdf"><span id="translatedtitle">New Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Sneden, Christopher; Cowan, John J; Ivans, Inese I; Hartog, Elizabeth A Den</p> <p>2009-01-01</p> <p>We have derived new abundances of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five <span class="hlt">elements</span> are in good agreement with meteoritic abundances. For the low metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other <span class="hlt">elements</span> in individual stars, to produce internally-consistent Ba, rare-<span class="hlt">earth</span>, and Hf (56<= Z <= 72) <span class="hlt">element</span> distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21269172','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21269172"><span id="translatedtitle">NEW RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENT</span> ABUNDANCE DISTRIBUTIONS FOR THE SUN AND FIVE r-PROCESS-RICH VERY METAL-POOR STARS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sneden, Christopher; Lawler, James E.; Den Hartog, Elizabeth A.; Cowan, John J.; Ivans, Inese I. E-mail: jelawler@wisc.edu E-mail: cowan@nhn.ou.edu</p> <p>2009-05-15</p> <p>We have derived new abundances of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five <span class="hlt">elements</span> are in good agreement with meteoritic abundances. For the low-metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other <span class="hlt">elements</span> in individual stars, to produce internally consistent Ba, rare <span class="hlt">earth</span>, and Hf (56 {<=} Z {<=} 72) <span class="hlt">element</span> distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002835','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002835"><span id="translatedtitle">Origin of Volatiles in <span class="hlt">Earth</span>: Indigenous Versus Exogenous Sources Based on Highly Siderophile, Volatile Siderophile, and Light Volatile <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, K.; Danielson, L.; Pando, K. M.; Marin, N.; Nickodem, K.</p> <p>2015-01-01</p> <p>Origin of <span class="hlt">Earth</span>'s volatiles has traditionally been ascribed to late accretion of material after major differentiation events - chondrites, comets, ice or other exogenous sources. A competing theory is that the <span class="hlt">Earth</span> accreted its volatiles as it was built, thus water and other building blocks were present early and during differentiation and core formation (indigenous). Here we discuss geochemical evidence from three groups of <span class="hlt">elements</span> that suggests <span class="hlt">Earth</span>'s volatiles were acquired during accretion and did not require additional sources after differentiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://lbmd.coe.pku.edu.cn/PDF/2015AB01.pdf','EPRINT'); return false;" href="http://lbmd.coe.pku.edu.cn/PDF/2015AB01.pdf"><span id="translatedtitle">Effect of the addition of low rare <span class="hlt">earth</span> <span class="hlt">elements</span> (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Zheng, Yufeng</p> <p></p> <p>Effect of the addition of low rare <span class="hlt">earth</span> <span class="hlt">elements</span> (lanthanum, neodymium, cerium focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare <span class="hlt">earth</span> in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GGG....13.1020H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GGG....13.1020H"><span id="translatedtitle">Online preconcentration ICP-MS analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in seawater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hathorne, Ed C.; Haley, Brian; Stichel, Torben; Grasse, Patricia; Zieringer, Moritz; Frank, Martin</p> <p>2012-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) with their systematically varying properties are powerful tracers of continental inputs, particle scavenging intensity and the oxidation state of seawater. However, their generally low (˜pmol/kg) concentrations in seawater and fractionation potential during chemical treatment makes them difficult to measure. Here we report a technique using an automated preconcentration system, which efficiently separates seawater matrix <span class="hlt">elements</span> and elutes the preconcentrated sample directly into the spray chamber of an ICP-MS instrument. The commercially available "seaFAST" system (<span class="hlt">Elemental</span> Scientific Inc.) makes use of a resin with ethylenediaminetriacetic acid and iminodiacetic acid functional groups to preconcentrate REEs and other metals while anions and alkali and alkaline <span class="hlt">earth</span> cations are washed out. Repeated measurements of seawater from 2000 m water depth in the Southern Ocean allows the external precision (2?) of the technique to be estimated at <23% for all REEs and <15% for most. Comparison of Nd concentrations with isotope dilution measurements for 69 samples demonstrates that the two techniques generally agree within 15%. Accuracy was found to be good for all REEs by using a five point standard addition analysis of one sample and comparing measurements of mine water reference materials diluted with a NaCl matrix with recommended values in the literature. This makes the online preconcentration ICP-MS technique advantageous for the minimal sample preparation required and the relatively small sample volume consumed (7 mL) thus enabling large data sets for the REEs in seawater to be rapidly acquired.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1110711L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1110711L"><span id="translatedtitle">Biological availability and environmental behaviour of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in soils of Hesse, Central Germany</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loell, M.; Duering, R.-A.; Felix-Henningsen, P.</p> <p>2009-04-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) comprise a group of 17 transition metals with very similar chemical and physical properties. They include the <span class="hlt">elements</span> scandium (Sc), yttrium (Y) and lanthanum (La) and the 14 <span class="hlt">elements</span> (cerium to lutetium) that follow La in the periodic table. Their average abundance in the <span class="hlt">earth</span>'s crust varies from 0,01 to 0,02% so they are as common as Cu and Pb. Beside their widespread use in industry, REEs are applied in Chinese agriculture. Their beneficial effects both on crop yield and on animal production are reported in various investigations. As a result - by using microelement fertilisers and manure - REEs enter the pedosphere while their fate and behaviour in the environment up to now remains unexamined. The first aim of our investigation was to evaluate the concentration of REEs in agricultural used soils in central Germany (Hesse) by ICP-MS. In addition to their total concentration (aqua regia digestion) their bioavailable contents - determined by EDTA (potentially available fraction) and ammonium nitrate extraction (mobile fraction) - were analysed. The occurrence of the three REE fractions in different soils will be discussed and influencing soil properties (e.g. pH-value, content of clay and organic carbon) will be revealed. Additionally the uptake of REEs by grassland plants was determined and resulting transfer factors will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/285526','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/285526"><span id="translatedtitle">The chemistry of the light rare-<span class="hlt">earth</span> <span class="hlt">elements</span> as determined by electron energy loss spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fortner, J.A.; Buck, E.C.</p> <p>1996-06-01</p> <p>The energy loss spectra of the rare <span class="hlt">earths</span> are characterized by sharp {ital M}{sub 4,5} edges, the relative intensities of which are characteristic of the 4{ital f}-shell occupancy of the excited ion. For the light rare <span class="hlt">earths</span>, the dependence of these relative peak heights on 4{ital f}-shell occupancy is quite pronounced. Thus they may be used to determine the oxidation state of the multivalent <span class="hlt">elements</span> Ce and Pr. The second derivative of the spectrum is shown to be extremely sensitive to the chemical environment. Modern instrumentation and detection techniques allow the oxidation state of Ce and Pr to be determined even when they are present as only minor constituents. {copyright} {ital 1996 American Institute of Physics.}</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AnGeo..32.1477B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AnGeo..32.1477B"><span id="translatedtitle">On the origin of falling-tone chorus <span class="hlt">elements</span> in <span class="hlt">Earth</span>'s inner magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Breuillard, H.; Agapitov, O.; Artemyev, A.; Krasnoselskikh, V.; Le Contel, O.; Cully, C. M.; Angelopoulos, V.; Zaliznyak, Y.; Rolland, G.</p> <p>2014-12-01</p> <p>Generation of extremely/very low frequency (ELF/VLF) chorus waves in <span class="hlt">Earth</span>'s inner magnetosphere has received increased attention recently because of their significance for radiation belt dynamics. Though past theoretical and numerical models have demonstrated how rising-tone chorus <span class="hlt">elements</span> are produced, falling-tone chorus <span class="hlt">element</span> generation has yet to be explained. Our new model proposes that weak-amplitude falling-tone chorus <span class="hlt">elements</span> can be generated by magnetospheric reflection of rising-tone <span class="hlt">elements</span>. Using ray tracing in a realistic plasma model of the inner magnetosphere, we demonstrate that rising-tone <span class="hlt">elements</span> originating at the magnetic equator propagate to higher latitudes. Upon reflection there, they propagate to lower L-shells and turn into oblique falling tones of reduced power, frequency, and bandwidth relative to their progenitor rising tones. Our results are in good agreement with comprehensive statistical studies of such waves, notably using magnetic field measurements from THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft. Thus, we conclude that the proposed mechanism can be responsible for the generation of weak-amplitude falling-tone chorus emissions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9673E..06W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9673E..06W"><span id="translatedtitle">Study on the activated laser welding of ferritic stainless steel with rare <span class="hlt">earth</span> <span class="hlt">elements</span> yttrium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Yonghui; Hu, Shengsun; Shen, Junqi</p> <p>2015-10-01</p> <p>The ferritic stainless steel SUS430 was used in this work. Based on a multi-component activating flux, composed of 50% ZrO2, 12.09 % CaCO3, 10.43 % CaO, and 27.49 % MgO, a series of modified activating fluxes with 0.5%, 1%, 2%, 5%, 10%, 15%, and 20% of rare <span class="hlt">earth</span> (RE) <span class="hlt">element</span> yttrium (Y) respectively were produced, and their effects on the weld penetration (WP) and corrosion resistant (CR) property were studied. Results showed that RE <span class="hlt">element</span> Y hardly had any effects on increasing the WP. In the FeCl3 spot corrosion experiment, the corrosion rates of almost all the samples cut from welded joints turned out to be greater than the parent metal (23.51 g/m2 h). However, there was an exception that the corrosion rate of the sample with 5% Y was only 21.96 g/m2 h, which was even better than parent metal. The further Energy Dispersive Spectrometer (EDS) test showed the existence of <span class="hlt">elements</span> Zr, Ca, O, and Y in the molten slag near the weld seam while none of them were found in the weld metal, indicating the direct transition of <span class="hlt">element</span> from activating fluxes to the welding seam did not exist. It was known that certain composition of activating fluxes effectively restrain the loss of Cr <span class="hlt">element</span> in the process of laser welding, and as a result, the CR of welded joints was improved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://arxiv.org/pdf/1311.5897v1','EPRINT'); return false;" href="http://arxiv.org/pdf/1311.5897v1"><span id="translatedtitle">New fission fragment distributions and r-process origin of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>S. Goriely; J. -L. Sida; J. -F. Lemaitre; S. Panebianco; N. Dubray; S. Hilaire; A. Bauswein; H. -Thomas Janka</p> <p>2013-11-22</p> <p>Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process <span class="hlt">elements</span> with nuclear mass numbers A > 140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular the fission fragment yields determine the creation of 110 rare-<span class="hlt">earth</span> peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r-nuclei with A > 140.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26515437','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26515437"><span id="translatedtitle">Levels of platinum group <span class="hlt">elements</span> and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in wild mushroom species growing in Poland.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mleczek, Miros?aw; Niedzielski, Przemys?aw; Kala?, Pavel; Siwulski, Marek; Rzymski, Piotr; G?secka, Monika</p> <p>2016-01-01</p> <p>Due to limited data-describing abilities of mushrooms to accumulate platinum group <span class="hlt">elements</span> (PGEs) and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), the aim of this study was to determine, by inductively coupled plasma optical emission spectrometry followed by microwave-assisted sample digestion by nitric acid, the content of these <span class="hlt">elements</span> in 20 mushroom species (10 above ground and 10 growing on wood), mostly edible, collected near a busy trunk road. The highest content of PGEs in above-ground mushroom species was observed in Lepista gilva and Suillus bovinus fruit bodies (0.38 ± 0.05 and 0.37 ± 0.03 mg kg(-1) DW, respectively), while in mushrooms growing on wood, the highest content was observed in Pleurotus ostreatus (0.35 ± 0.04 mg kg(-1) DW). The mean content of PGEs for both these groups was 0.23 ± 0.08 and 0.26 ± 0.07 mg kg(-1) DW, respectively. The highest content of REEs in Suillus luteus and Tricholoma equestra was 5.03 ± 0.50 and 2.18 ± 0.56 mg kg(-1) DW, respectively, but within mushrooms growing on wood in Ganoderma applanatum fruiting bodies it was 4.19 ± 0.78 mg kg(-1) DW. Mean contents of REEs were 1.39 ± 1.21 and 1.61 ± 0.97 mg kg(-1) DW in above-ground species and species growing on wood, respectively. Generally, the group of mushroom species growing on wood was capable of slightly higher accumulation of both REEs and PGEs. No limits have been established for both the groups until now. PMID:26515437</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011GeCoA..75.1451S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.1451S"><span id="translatedtitle">Systematics of metal-silicate partitioning for many siderophile <span class="hlt">elements</span> applied to <span class="hlt">Earth’s</span> core formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siebert, Julien; Corgne, Alexandre; Ryerson, Frederick J.</p> <p>2011-03-01</p> <p>Superliquidus metal-silicate partitioning was investigated for a number of moderately siderophile (Mo, As, Ge, W, P, Ni, Co), slightly siderophile (Zn, Ga, Mn, V, Cr) and refractory lithophile (Nb, Ta) <span class="hlt">elements</span>. To provide independent constrains on the effects of temperature, oxygen fugacity and silicate melt composition, isobaric (3 GPa) experiments were conducted in piston cylinder apparatus at temperature between 1600 and 2600 °C, relative oxygen fugacities of IW-1.5 to IW-3.5, and for silicate melt compositions ranging from basalt to peridotite. The effect of pressure was investigated through a combination of piston cylinder and multi-anvil isothermal experiments between 0.5 and 18 GPa at 1900 °C. Oxidation states of siderophile <span class="hlt">elements</span> in the silicate melt as well as effect of carbon saturation on partitioning are also derived from these results. For some <span class="hlt">elements</span> (e.g. Ga, Ge, W, V, Zn) the observed temperature dependence does not define trends parallel to those modeled using metal-metal oxide free energy data. We correct partitioning data for solute interactions in the metallic liquid and provide a parameterization utilized in extrapolating these results to the P- T- X conditions proposed by various core formation models. A single-stage core formation model reproduces the mantle abundances of several siderophile <span class="hlt">elements</span> (Ni, Co, Cr, Mn, Mo, W, Zn) for core-mantle equilibration at pressures from 32 to 42 GPa along the solidus of a deep peridotitic magma ocean (˜3000 K for this pressure range) and oxygen fugacities relevant to the FeO content of the present-day mantle. However, these P- T- fO 2 conditions cannot produce the observed concentrations of Ga, Ge, V, Nb, As and P. For more reducing conditions, the P- T solution domain for single stage core formation occurs at subsolidus conditions and still cannot account for the abundances of Ge, Nb and P. Continuous core formation at the base of a magma ocean at P- T conditions constrained by the peridotite liquidus and fixed fO 2 yields concentrations matching observed values for Ni, Co, Cr, Zn, Mn and W but underestimates the core/mantle partitioning observed for other <span class="hlt">elements</span>, notably V, which can be reconciled if accretion began under reducing conditions with progressive oxidation to fO 2 conditions consistent with the current concentration of FeO in the mantle as proposed by Wade and Wood (2005). However, neither oxygen fugacity path is capable of accounting for the depletions of Ga and Ge in the <span class="hlt">Earth</span>'s mantle. To better understand core formation, we need further tests integrating the currently poorly-known effects of light <span class="hlt">elements</span> and more complex conditions of accretion and differentiation such as giant impacts and incomplete equilibration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860050790&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DPeridotite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860050790&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DPeridotite"><span id="translatedtitle">Transition region of the <span class="hlt">earth</span>'s upper mantle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, D. L.; Bass, J. D.</p> <p>1986-01-01</p> <p>The chemistry of the <span class="hlt">earth</span>'s mantle is discussed using data from cosmochemistry, <span class="hlt">geochemistry</span>, petrology, seismology, and mineral physics. The chondritic <span class="hlt">earth</span>, the upper mantle and the 400-km discontinuity, the transition region, lower mantle mineralogy, and surface wave tomography are examined. Three main issues are addressed: (1) whether the mantle is homogeneous in composition or chemically stratified, (2) whether the major <span class="hlt">element</span> chemistry of the mantle is more similar to upper mantle peridotites or to chondrites, and (3) the nature of the composition of the source region of basalts erupted at midocean ridges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://arxiv.org/pdf/1503.08708.pdf','EPRINT'); return false;" href="http://arxiv.org/pdf/1503.08708.pdf"><span id="translatedtitle">Thulium anomalies and rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns in meteorites and <span class="hlt">Earth</span>: Nebular fractionation and the nugget effect</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Dauphas, N</p> <p>2015-01-01</p> <p>This study reports the bulk rare <span class="hlt">earth</span> <span class="hlt">element</span> (REEs, La-Lu) compositions of 41 chondrites, including 32 falls and 9 finds from carbonaceous (CI, CM, CO and CV), enstatite (EH and EL) and ordinary (H, L and LL) groups, as well as 2 enstatite achondrites (aubrite). The CI-chondrite-normalized REE patterns and Eu anomalies in ordinary and enstatite chondrites show more scatter in more metamorphosed than in unequilibrated chondrites. This is due to parent-body redistribution of the REEs in various carrier phases during metamorphism. The dispersion in REE patterns of equilibrated ordinary chondrites is explained by the nugget effect associated with concentration of REEs in minor phosphate grains. Terrestrial rocks and samples from ordinary and enstatite chondrites display negative Tm anomalies of ~-4.5 % relative to ca chondrites. In contrast, CM, CO and CV (except Allende) show no significant Tm anomalies. Allende CV chondrite shows large excess Tm (~+10 %). These anomalies are similar to those found in group II...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IJMMM..22..453L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IJMMM..22..453L"><span id="translatedtitle">Application of rare-<span class="hlt">earth</span> <span class="hlt">element</span> Y in refining impure copper</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Hai-hong; Sun, Xue-qin; Zhang, Shang-zhou; Zhao, Qin-yi; Wang, Guang-zhen</p> <p>2015-05-01</p> <p>The effects of rare-<span class="hlt">earth</span> <span class="hlt">element</span> Y in refining impure copper were investigated in this paper. The composition, microstructures, and corrosion resistance properties of impure copper before and after refinement with Y were investigated using direct-reading spectrometry, inductively coupled plasma atomic emission spectrometry, optical microscopy, scanning electron microscopy, and potentiodynamic polarization measurements. The results show that the concentrations of impurities S, As, Sb, Bi, Al, Cd, and Se are remarkably decreased. Adding an appropriate amount of Y refines the microstructure and enhances the corrosion resistance properties of impure copper in HCl solution via a purification effect. The formation enthalpies of compounds formed between Y and various impurity <span class="hlt">elements</span> were calculated on the basis of Miedema's theory. The thermodynamic mechanisms of the refinement of impure copper by Y were also discussed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983Natur.306..172R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983Natur.306..172R"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in chondritic phosphates - Implications for PU-244 chronology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reed, S. J. B.; Long, J. V. P.; Smith, D. G. W.</p> <p>1983-11-01</p> <p>Ion-probe measurements were made of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in chondritic phosphates. A 20-micron beam of O-16(-) ions was used to bombard thin phosphate sections. A computer-controlled mass spectrometer was employed to analyze the peaks generated by the beam scan. When interferences from matrixes in the samples were encountered, the intensities of major isotopes were compared with reference intensities, and the peaks of isotopes showing the lowest interference were selected. REE concentrations of apatite and merrillite in Barbotan and Salles chondrites are reported, showing that REE is five times higher in concentration than apatite. It is concluded that the REE <span class="hlt">elements</span> can be successfully substituted as a Pu analog for dating the chondritic phosphate materials in regards to their formation time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018161','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018161"><span id="translatedtitle">Record of middle Pleistocene climate change from Buck Lake, Cascade Range, southern Oregon - Evidence from sediment magnetism, trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span>, and pollen</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rosenbaum, J.G.; Reynolds, R.L.; Adam, D.P.; Drexler, J.; Sarna-Wojcicki, A. M.; Whitney, G.C.</p> <p>1996-01-01</p> <p>Comparison of systematic variations in sediment magnetic properties to changes in pollen assemblages in middle Pleistocene lake sediments from Buck Lake indicates that the magnetic properties are sensitive to changes in climate. Buck Lake is located in southern Oregon just east of the crest of the Cascade Range. Lacustrine sediments, from 5.2 to 19.4 m in depth in core, contain tephra layers with ages of ???300-400 ka at 9.5 m and ???400-470 ka at 19.9 m. In these sediments magnetic properties reflect the absolute amount and relative abundances of detrital Fe-oxide minerals, titanomagnetite and hematite. The lacustrine section is divided into four zones on the basis of magnetic properties. Two zones (19.4-17.4 m and 14.5-10.3 m) of high magnetic susceptibility contain abundant Fe oxides and correspond closely to pollen zones that are indicative of cold, dry environments. Two low-susceptibility zones (17.4-14.5 m and 10.3-5.3 m) contain lesser amounts of Fe oxides and largely coincide with zones of warm-climate pollen. Transitions from cold to warm climate based on pollen are preceded by sharp changes in magnetic properties. This relation suggests that land-surface processes responded to these climate changes more rapidly than did changes in vegetation as indicated by pollen frequencies. Magnetic properties have been affected by three factors: (1) dissolution of Fe oxides, (2) variation in heavy-mineral content, and (3) variation in abundance of fresh volcanic rock fragments. Trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span>, employing Fe and the immobile <span class="hlt">elements</span> Ti and Zr, is utilized to detect postdepositional dissolution of magnetic minerals that has affected the magnitude of magnetic properties with little effect on the pattern of magnetic-property variation. Comparison of Ti and Zr values, proxies for heavy-mineral content, to magnetic properties demonstrates that part of the variation in the amount of magnetite and nearly all of the variation in the amount of hematite are due to changes in heavy-mineral content. Variation in the quantity of fresh volcanic rock fragments is the other source of change in magnetite content. Magnetic-property variations probably arise primarily from changes in peak runoff. At low to moderate flows magnetic properties reflect only the quantities of heavy minerals derived from soil and highly weathered rock in the catchment. At high flows, however, fresh volcanic rock fragments may be produced by breaking of pebbles and cobbles, and such fragments greatly increase the magnetite content of the resulting sediment. Climatically controlled factors that would affect peak runoff levels include the accumulation and subsequent melting of winter snow pack, the seasonality of precipitation, and the degree of vegetation cover of the land surface. Our results do not distinguish amont the possible contributions of these disparate factors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1624J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1624J"><span id="translatedtitle">The formation conditions of enstatite chondrites: Insights from trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of olivine-bearing chondrules in Sahara 97096 (EH3)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jacquet, Emmanuel; Alard, Olivier; Gounelle, Matthieu</p> <p>2015-09-01</p> <p>We report in situ LA-ICP-MS trace <span class="hlt">element</span> analyses of silicate phases in olivine-bearing chondrules in the Sahara 97096 (EH3) enstatite chondrite. Most olivine and enstatite present rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns comparable to their counterparts in type I chondrules in ordinary chondrites. They thus likely share a similar igneous origin, likely under similar redox conditions. The mesostasis however frequently shows negative Eu and/or Yb (and more rarely Sm) anomalies, evidently out of equilibrium with olivine and enstatite. We suggest that this reflects crystallization of oldhamite during a sulfidation event, already inferred by others, during which the mesostasis was molten, where the complementary positive Eu and Yb anomalies exhibited by oldhamite would have possibly arisen due to a divalent state of these <span class="hlt">elements</span>. Much of this igneous oldhamite would have been expelled from the chondrules, presumably by inertial acceleration or surface tension effects, and would have contributed to the high abundance of opaque nodules found outside them in EH chondrites. In two chondrules, olivine and enstatite exhibit negatively sloped REE patterns, which may be an extreme manifestation of a general phenomenon (possibly linked to near-liquidus partitioning) underlying the overabundance of light REE observed in most chondrule silicates relative to equilibrium predictions. The silicate phases in one of these two chondrules show complementary Eu, Yb, and Sm anomalies providing direct evidence for the postulated occurrence of the divalent state for these <span class="hlt">elements</span> at some stage in the formation reservoir of enstatite chondrites. Our work supports the idea that the peculiarities of enstatite chondrites may not require a condensation sequence at high C/O ratios as has long been believed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993AcSpe..48..507S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993AcSpe..48..507S"><span id="translatedtitle">Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in high purity rare <span class="hlt">earth</span> oxides by liquid chromatography, thermionic mass spectrometry and combined liquid chromatography/thermionic mass spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stijfhoorn, D. E.; Stray, H.; Hjelmseth, H.</p> <p>1993-03-01</p> <p>A high-performance liquid Chromatographie (HPLC) method for the determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in rocks has been modified and used for the determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in high purity rare <span class="hlt">earth</span> oxides. The detection limit was 1-1.5 ng or 2-3 mg/kg when a solution corresponding to 0.5 mg of the rare <span class="hlt">earth</span> oxide was injected. The REE determination was also carried out by adding a mixture of selected REE isotopes to the sample and analysing the collected HPLC-fractions by mass spectrometry (MS) using a thermionic source. Since the matrix <span class="hlt">element</span> was not collected, interference from this <span class="hlt">element</span> during the mass spectrometric analysis was avoided. Detection limits as low as 0.5 mg/kg could then be obtained. Detection limits as low as 0.05 mg/kg were possible by MS without HPLC-pre-separation, but this approach could only be used for those <span class="hlt">elements</span> that were not affected by the matrix. Commercial samples of high purity Nd 2O 3, Gd 2O 3 and Dy 2O 3 were analysed in this study, and a comparison of results obtained by HPLC, combined HPLC/MS and direct MS are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26674238','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26674238"><span id="translatedtitle">An EDTA-?-cyclodextrin material for the adsorption of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and its application in preconcentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in seawater.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Feiping; Repo, Eveliina; Meng, Yong; Wang, Xueting; Yin, Dulin; Sillanpää, Mika</p> <p>2016-03-01</p> <p>The separation and recovery of Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) from diluted aqueous streams has attracted great attention in recent years because of ever-increasing REEs demand. In this study, a green synthesized EDTA-cross-linked ?-cyclodextrin (EDTA-?-CD) biopolymer was prepared and employed in adsorption of aqueous REEs, such as La(III), Ce(III), and Eu(III). EDTA acts not only as cross-linker but also as coordination site for binding of REEs. The adsorption properties for the adsorption of REEs by varying experimental conditions were carried out by batch tests. The kinetics results revealed that the surface chemical sorption and the external film diffusion were the rate-determining steps of the adsorption process. The obtained maximum adsorption capacities of EDTA-?-CD were 0.343, 0.353, and 0.365mmolg(-1) for La(III), Ce(III) and Eu(III), respectively. Importantly, the isotherms fitted better to Langmuir than Freundlich and Sips models, suggesting a homogenous adsorption surface for REEs on the adsorbent. Moreover, the multi-component adsorption, which was modeled by extended Sips isotherms, revealed adsorbent's selectivity to Eu(III). More significantly, the successful recoveries of the studied ions from tap water and seawater samples makes EDTA-?-CD a promising sorbent for the preconcentration of REEs from diluted aqueous streams. PMID:26674238</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750007645','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750007645"><span id="translatedtitle"><span class="hlt">Earth</span> Observatory Satellite system definition study. Report no. 5: System design and specifications. Part 1: Observatory system <span class="hlt">element</span> specifications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1974-01-01</p> <p>The performance, design, and quality assurance requirements for the <span class="hlt">Earth</span> Observatory Satellite (EOS) Observatory and Ground System program <span class="hlt">elements</span> required to perform the Land Resources Management (LRM) A-type mission are presented. The requirements for the Observatory <span class="hlt">element</span> with the exception of the instruments specifications are contained in the first part.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70039454','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70039454"><span id="translatedtitle"><span class="hlt">Earth</span> Science Information System (ESIS)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>U.S. Geological Survey</p> <p>1982-01-01</p> <p>The <span class="hlt">Earth</span> Science Information System (ESIS) was developed in 1981 by the U.S. Geological Survey's Office of the Data Administrator. ESIS serves as a comprehensive data management facility designed to support the coordination, integration, and standardization of scientific, technical, and bibliographic data of the U.S. Geological Survey (USGS). ESIS provides, through an online interactive computer system, referral to information about USGS data bases, data <span class="hlt">elements</span> which are fields in the records of data bases, and systems. The data bases contain information about many subjects from several scientific disciplines such as: geology, geophysics, <span class="hlt">geochemistry</span>, hydrology, cartography, oceanography, geography, minerals exploration and conservation, and satellite data sensing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JPS...179..763I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JPS...179..763I"><span id="translatedtitle">Electrical and dielectric properties of lithium manganate nanomaterials doped with rare-<span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iqbal, Muhammad Javed; Ahmad, Zahoor</p> <p>2008-05-01</p> <p>Substituted LiRxMn2 - xO4 (R = La3+, Ce3+, Pr3+ and x = 0.00 - 0.20) nanoparticles are prepared by the sol-gel method and the consequent changes in their lattice structure, dielectric and electrical parameters are determined by XRD, ED-XRF, SEM, LCR meter bridge and dc electrical resistivity measurements. Diffraction data show that the samples are single-phase spinel materials with crystallites sizes between 21 and 38 nm. The lattice parameter, cell volume and X-ray density are found to be affected by doping the Li-manganate with the rare-<span class="hlt">earth</span> <span class="hlt">elements</span>. The ED-XRF analysis confirms the stoichiometric composition of the synthesized samples and SEM reveals their morphology. Calculated values of the dielectric constant (?) and the dielectric loss (tan ?) decrease with the frequency of the applied field. This is attributed to Maxwell-Wagner polarization. Replacement of manganese by the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> results in an improvement in the structural stability of the material, which is considered to be useful for enhancement of the cycleability of the compounds when used in lithium rechargeable batteries, and increases significantly the values of ? and tan ? (except for Ce). Lithium manganate nanomaterials with high ? and low tan ? may be attractive for application in memory storage devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93R.202S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93R.202S"><span id="translatedtitle">While China's dominance in rare <span class="hlt">earths</span> dips, concerns remain about these and other <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Showstack, Randy</p> <p>2012-05-01</p> <p>China's dominance in the production of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) peaked with that nation producing 97% of them in 2010; this number already has dipped to 90% in 2012 as mines in other nations are coming online, according to REE expert Karl Gschneidner Jr., a professor at Iowa State University's Ames Laboratory. Chinese production could drop to 60% by 2014, with production increasing at mines in the United States and other countries, he said. However, this reduction in China's share of REE production does not signal an end to the production crisis in REEs and other critical minerals, Gschneidner and others noted during a 1 May panel discussion on critical materials shortages at the AGU Science Policy Conference in Washington, D. C. REEs are a group of 17 chemically similar metallic <span class="hlt">elements</span> used in a variety of electronic, optical, magnetic, and catalytic applications, and despite their name, they are relatively plentiful in the <span class="hlt">Earth</span>'s crust. China's control of known REE reserves has dropped from 75% in 1975 to 30.9% in 2012, with other regions also having large reserves, including the Commonwealth of Independent States (some former Soviet Republic states), the United States, and Australia, according to Gschneidner. Critical minerals are mineral commodities that are particularly important for a nation's economy or national defense that could potentially face supply disruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5798936','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5798936"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soils from selected areas on the Island of Hawaii</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barnard, W.M.; Halbig, J.B.</p> <p>1985-07-01</p> <p>Fifty soil samples for the wet, windward (east) side and dry, leeward (west) side of the Island of Hawaii were analyzed for La, Ce, Sm, Eu, Yb, and Lu by neutron activation/gamma-ray spectroscopic analysis. Data on concentrations in each sample are listed and analyzed statistically for soil samples collected from the western slope of Kohala Mountain, the western coastal plain of Mauna Kea, and the Northeastern coastal plain of Maunal Loa. Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations are two to six times greater in soils from the western, dry side of the island, and good statistical correlation is exhibited among the samples for pairs of individual REEs. In the organic-rich soils of the east side, correlations are poor but are markedly improved when sample weights are adjusted for weight due to organic matter and water in soil colloids. If the mean compositions of selected rock samples from the Hawaii Reference Suite are representative of the compositions of the parent materials, REEs in the soils are moderately enriched (up to two times, based on oven-dry weights). Rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in the island's western soils are as much as two times greater than the mean REE values of common sedimentary rocks worldwide; however, they are well within the concentration ranges of soils of continental origin. The eastern soils tend to have less La and Ce, but similar amounts of the middle and heavy REEs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25278442','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25278442"><span id="translatedtitle">Effect of the addition of low rare <span class="hlt">earth</span> <span class="hlt">elements</span> (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> are promising alloying <span class="hlt">element</span> candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations. We showed that low concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> do not promote bone growth inside a 750 ?m broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare <span class="hlt">earth</span> <span class="hlt">element</span> alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. PMID:25278442</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25283836','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25283836"><span id="translatedtitle">Recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from the sulfothermophilic red alga Galdieria sulphuraria using aqueous acid.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Minoda, Ayumi; Sawada, Hitomi; Suzuki, Sonoe; Miyashita, Shin-ichi; Inagaki, Kazumi; Yamamoto, Takaiku; Tsuzuki, Mikio</p> <p>2015-02-01</p> <p>The demand for rare <span class="hlt">earth</span> <span class="hlt">elements</span> has increased dramatically in recent years because of their numerous industrial applications, and considerable research efforts have consequently been directed toward recycling these materials. The accumulation of metals in microorganisms is a low-cost and environmentally friendly method for the recovery of metals present in the environment at low levels. Numerous metals, including rare <span class="hlt">earth</span> <span class="hlt">elements</span>, can be readily dissolved in aqueous acid, but the efficiency of metal biosorption is usually decreased under the acidic conditions. In this report, we have investigated the use of the sulfothermophilic red alga Galdieria sulphuraria for the recovery of metals, with particular emphasis on the recovery of rare <span class="hlt">earth</span> metals. Of the five different growth conditions investigated where G. sulphuraria could undergo an adaptation process, Nd(III), Dy(III), and Cu(II) were efficiently recovered from a solution containing a mixture of different metals under semi-anaerobic heterotrophic condition at a pH of 2.5. G. sulphuraria also recovered Nd(III), Dy(III), La(III), and Cu(II) with greater than 90% efficiency at a concentration of 0.5 ppm. The efficiency remained unchanged at pH values in the range of 1.5-2.5. Furthermore, at pH values in the range of 1.0-1.5, the lanthanoid ions were collected much more efficiently into the cell fractions than Cu(II) and therefore successfully separated from the Cu(II) dissolved in the aqueous acid. Microscope observation of the cells using alizarin red suggested that the metals were accumulating inside of the cells. Experiments using dead cells suggested that this phenomenon was a biological process involving specific activities within the cells. PMID:25283836</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.whoi.edu/science/MCG/groundwater/pubs/PDF/Charette_GCA_2005.pdf','EPRINT'); return false;" href="http://www.whoi.edu/science/MCG/groundwater/pubs/PDF/Charette_GCA_2005.pdf"><span id="translatedtitle">doi:10.1016/j.gca.2004.10.024 Trace <span class="hlt">element</span> cycling in a subterranean estuary</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p></p> <p></p> <p>doi:10.1016/j.gca.2004.10.024 Trace <span class="hlt">element</span> cycling in a subterranean estuary: Part 1. <span class="hlt">Geochemistry</span> February 17, 2004; accepted in revised form October 25, 2004) Abstract--Subterranean estuaries estuaries, like their river water-seawater counterparts on the surface of the <span class="hlt">earth</span>, represent a major</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012107','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012107"><span id="translatedtitle">Composition of the <span class="hlt">earth</span>'s upper mantle-I. Siderophile trace <span class="hlt">elements</span> in ultramafic nodules</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morgan, J.W.; Wandless, G.A.; Petrie, R.K.; Irving, A.J.</p> <p>1981-01-01</p> <p>Seven siderophile <span class="hlt">elements</span> (Au, Ge, Ir, Ni, Pd, Os, Re) were determined by radiochemical neutron activation analysis in 19 ultramafic rocks, which are spinel lherzollites-xenoliths from North and Central America, Hawaii and Australia, and garnet Iherzolitexenoliths from Lesotho. Abundances of the platinum metals are very uniform in spinel lherzolites averaging 3.4 ?? 1.2 ppb Os, 3.7 ?? 1.1 ppb Ir, and 4.6 ?? 2.0 ppb Pd. Sheared garnet lherzolite PHN 1611 has similar abundances of these <span class="hlt">elements</span>, but in 4 granulated garnet lherzolites, abundances are more variable. In all samples, the Pt metals retain cosmic ( Cl-chondrite) ratios. Abundances of Au and Re vary more than those of Pt metals, but the Au/Re ratio remains close to the cosmic value. The fact that higher values of Au and Re approach cosmic proportions with respect to the Pt metals, suggests that Au and Re have been depleted in some ultramafic rocks from an initially chondrite-like pattern equivalent to about 0.01 of Cl chondrite abundances. The relative enrichment of Au and Re in crustal rocks is apparently the result of crust-mantle fractionation and does not require a special circumstance of core-mantle partitioning. Abundances of moderately volatile <span class="hlt">elements</span> Ni, Co and Ge are very uniform in all rocks, and are much higher than those of the highly siderophile <span class="hlt">elements</span> Au, Ir, Pd, Os and Re. When normalized to Cl chondrites, abundances of Ni and Co are nearly identical, averaging 0.20 ?? 0.02 and 0.22 ?? 0.02, respectively; but Ge is only 0.027 ?? 0.004. The low abundance of Ge relative to Ni and Co is apparently a reflection of the general depletion of volatile <span class="hlt">elements</span> in the <span class="hlt">Earth</span>. The moderately siderophile <span class="hlt">elements</span> cannot be derived from the same source as the highly siderophile <span class="hlt">elements</span> because of the marked difference in Cl chondrite-normalized abundances and patterns. We suggest that most of the Ni, Co and Ge were enriched in the silicate by the partial oxidation of pre-existing volatile-poor Fe-Ni, whereas the corresponding highly siderophile <span class="hlt">elements</span> remained sequestered by the surviving metal. The highly siderophile <span class="hlt">elements</span> may have been introduced by a population of ~103 large (~1022 g) planetisimals, similar to those forming the lunar mare basins. ?? 1981.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6700515','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6700515"><span id="translatedtitle">Annual review of <span class="hlt">earth</span> and planetary sciences. Volume 8</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Donath, F.A.; Stehli, F.G.; Wetherill, G.W.</p> <p>1980-01-01</p> <p>Papers are presented on the <span class="hlt">geochemistry</span> of evaporitic lacustrine deposits, the deformation of mantle rocks, the dynamics of sudden stratospheric warmings, the equatorial undercurrent, geomorphological processes on planetary surfaces, and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in petrogenetic studies of igneous systems. Consideration is also given to evolutionary patterns in early Cenozoic animals, the origin and evolution of planetary atmospheres, the moons of Mars, and refractory inclusions in the Allende meteorite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JSAES..16..205M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JSAES..16..205M"><span id="translatedtitle">Major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and 40Ar/ 39Ar geochronology of Laramide plutonic rocks associated with gold-bearing Fe skarn deposits in Guerrero state, southern Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meza-Figueroa, D.; Valencia-Moreno, M.; Valencia, V. A.; Ochoa-Landín, L.; Pérez-Segura, E.; Díaz-Salgado, C.</p> <p>2003-08-01</p> <p>Fe-Au skarn deposits related to intrusive centers, mostly of granodioritic composition, are widespread in southern Mexico's Guerrero state. These intrusive rocks are largely associated with the NW-SE-oriented Laramide magmatic belt that extends across most of western Mexico. The geochemical composition and ages of representative rocks from the Mezcala mining district in central Guerrero are studied to evaluate the petrogenetic aspects of the ore-related magmas. Some major and trace <span class="hlt">elements</span> display nearly linear silica variation trends, which suggest a possible comagmatic origin. However, other <span class="hlt">elements</span> have scattered distributions, possibly due to irregular mantle-to-crust magma mixing ratios, heterogeneities in the composition of the assimilated crustal material, or modifications during the emplacement or postemplacement processes. Major <span class="hlt">element</span> chemistry indicates calc-alkalic metaluminous compositions, whereas trace <span class="hlt">element</span> data suggest a volcanic arc tectonic setting, confirming that these rocks evolved from magmas generated above a subduction zone. Compared with the Laramide granites from the northern part of the belt in northwestern Mexico, which intruded a crust underlain by Proterozoic North American rocks, the studied samples are similar but relatively low in Nb and high in Sr, the middle rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE), P, and Zr. They also display minor Ti enrichments and a moderate depletion in the heavy REE. These characteristics may indicate a source of basaltic composition. New 40Ar/ 39Ar dating of granodiorites and dacite porphyries shows a north-to-south age progression from 66.2±0.8 Ma in the northern part of the belt to 62.2±0.7 Ma in the south. Moreover, the argon dates identify a younger postorogenic igneous event 35-30 Ma ago. This event is poorly documented and may have occurred after the extinction of the Laramide arc and prior to the mid-Tertiary Sierra Madre Occidental ignimbrite flare-up. On the basis of limited geochemical data, these rocks appear to be depleted in P 2O 5 and Sr and enriched in U relative to the studied Laramide granites. A Fe skarn deposit located in Buena Vista de Cuéllar, in the north central part of Guerrero, suggests that this magmatic pulse took place after the ore development of the Mezcala district.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015FrEaS...3....6H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015FrEaS...3....6H"><span id="translatedtitle">Assessing the utility of trace and rare <span class="hlt">earth</span> <span class="hlt">elements</span> as biosignatures in microbial iron oxyhydroxides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heim, Christine; Simon, Klaus; Ionescu, Danny; Reimer, Andreas; De Beer, Dirk; Quéric, Nadia-Valérie; Reitner, Joachim; Thiel, Volker</p> <p>2015-02-01</p> <p>Microbial iron oxyhydroxides are common deposits in natural waters, recent sediments and mine drainage systems and often contain significant accumulations of trace and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (TREE). TREE patterns are widely used to characterize minerals and rocks, and to elucidate their evolution and origin. Whether and which characteristic TREE signatures distinguish between a biological and an abiological origin of iron minerals is still not well understood. Long-term flow reactor studies were performed in the Äspö Hard Rock Laboratory to investigate the development of microbial mats dominated by iron-oxidizing bacteria, namely Mariprofundus sp. and Gallionella sp. The experiments investigated the accumulation and fractionation of TREE under controlled conditions and enabled us to assess potential biosignatures evolving within the microbial iron oxyhydroxides. Concentrations of Be, Y, Zn, Zr, Hf, W, Th, Pb, and U in the microbial mats were 1e3- to 1e5-fold higher than in the feeder fluids whereas the rare <span class="hlt">earth</span> <span class="hlt">elements</span> and Y (REE+Y) contents were 1e4 and 1e6 fold enriched. Except for a hydrothermally induced Eu anomaly, the normalized REE+Y patterns of the microbial iron oxyhydroxides were very similar to published REE+Y distributions of Archaean Banded Iron Formations. The microbial iron oxyhydroxides from the flow reactors were compared to iron oxyhydroxides that were artificially precipitated from the same feeder fluid. These abiotic and inorganic iron oxyhydroxides show the same REE+Y distribution patterns. Our results indicate that the REE+Y mirror quite exactly the water chemistry, but they do not allow to distinguish microbially mediated from inorganic iron precipitates. All TREE studied showed an overall similar fractionation behavior in biogenic, abiotic and inorganic iron oxyhydroxides. Exceptions are Ni and Tl, which were only accumulated in the microbial iron oxyhydroxides and may point to a potential usage of these <span class="hlt">elements</span> as microbial biosignatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15478941','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15478941"><span id="translatedtitle">Distribution characteristics of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in children's scalp hair from a rare <span class="hlt">earths</span> mining area in southern China.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tong, Shi-Lu; Zhu, Wang-Zhao; Gao, Zhao-Hua; Meng, Yu-Xiu; Peng, Rui-Ling; Lu, Guo-Cheng</p> <p>2004-01-01</p> <p>In order to demonstrate the validity of using scalp hair rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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. PMID:15478941</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B32D..03Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B32D..03Z"><span id="translatedtitle">Cracking the Code of Soil Genesis. The Early Role of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaharescu, D. G.; Dontsova, K.; Burghelea, C. I.; Maier, R. M.; Huxman, T. E.; Chorover, J.</p> <p>2014-12-01</p> <p>Soil is terrestrial life support system. Its genesis involves tight interactions between biota and mineral surfaces that mobilize structural <span class="hlt">elements</span> into biogeochemical cycles. Of all chemical <span class="hlt">elements</span> rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are a group of 16 non-nutrient <span class="hlt">elements</span> 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 <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850010583&hterms=earths+tectonic+plate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dearths%2Btectonic%2Bplate','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850010583&hterms=earths+tectonic+plate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dearths%2Btectonic%2Bplate"><span id="translatedtitle"><span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Carr, M. H.</p> <p>1984-01-01</p> <p>The following aspects of the planet <span class="hlt">Earth</span> are discussed: plate tectonics, the interior of the planet, the formation of the <span class="hlt">Earth</span>, and the evolution of the atmosphere and hydrosphere. The <span class="hlt">Earth</span>'s crust, mantle, and core are examined along with the bulk composition of the planet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAfES..91...66K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAfES..91...66K"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and petrogenesis of the granitoids and high-K andesite hosting gold mineralisation in the Archean Musoma-Mara Greenstone Belt, Tanzania</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kazimoto, Emmanuel Owden; Ikingura, Justinian R.</p> <p>2014-03-01</p> <p>Modern and ancient active continental margins are well known for their potential for hosting important gold deposits. The Neoarchean Musoma-Mara Greenstone Belt of the Tanzania Craton is also known for hosting several important gold deposits. Previous geochemical studies of the belt demonstrated that the rocks formed along Neoarchean convergent margins. The host rocks of the three important deposits in this belt had not yet been geochemically investigated. Therefore, we studied the host rocks of the Gokona, Nyabigena and Nyabirama gold deposits in the Neoarchean Musoma-Mara Greenstone Belt of the Tanzania Craton to determine the tectonic setting of their formation and constrain their petrogenesis. The host rocks of the Gokona and Nyabigena deposits are classified as high-K andesite, whereas the host rocks of the Nyabirama deposit are classified primarily as trondhjemite and granite and minor granodiorite (TGG). The high-K andesite and TGG were formed in an active continental margin similar to that of other Neoarchean volcanic rocks found in the Musoma-Mara Greenstone Belt. The host rocks contain low Ni and Cr concentrations and are characterised by negative Eu anomalies (Eu/Eu* = 0.67-0.72 and 0.17-0.6). The chondrite-normalised rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns of the rocks display strong enrichment in light REEs over heavy REEs (high-K andesite (La/Yb)N = 21.7-35.6, and TGG (La/Yb)N = 2.4-94.4). Moreover, the primitive normalised diagrams show enrichment in large-ion lithophile <span class="hlt">elements</span> (Ba, Rb, Th and K), negative Nb and Ta anomalies and depletion in heavy rare <span class="hlt">earth</span> <span class="hlt">elements</span> and high field-strength <span class="hlt">elements</span> (Y and Ti). The high-K andesite has a Nb/Ta value close to that of depleted mantle (mean = 15.0), lower Zr/Sm values (19.4-30.6) and higher concentrations of REEs, large ion lithophile <span class="hlt">elements</span>, Sr (607 ppm) and Y than in the TGG. The TGG has a low mean Nb/Ta value (13.2) and Sr concentration (283 ppm) and a lower amount of HREEs and higher values of Zr/Sm (32.5-91.0) compared to the high-K andesite. However, all of the rock types contain high Ta/Yb and Th/Yb values (high-K andesite and granitoids; mean = 5.9 and 0.8, 17 and 21.3). These characteristics are interpreted as an indication of the formation of the Gokona, Nyabigena and Nyabirama host rocks from the hydrous partial melting of mantle peridotite, similar to the evolution of classical island arc rocks. The primary melts subsequently underwent fractional crystallisation to form high-K andesite, dacite and TGG prior to their extrusion or emplacement in the continental crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18329796','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18329796"><span id="translatedtitle">Chemical properties of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in typical medical waste incinerator ashes in China.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Lijuan; Zhang, Fu-Shen; Zhang, Jingxin</p> <p>2008-10-30</p> <p>Medical waste (MW) ashes from different types of MW incinerators were examined to detect the characteristics and environmental impact of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs). The results showed that total REE contents in the ash samples ranged from 10.2 to 78.9 mg/kg. REEs in bottom ash were apparently higher than those in fly ash. Average REE contents in the ashes followed the sequence of Ce>La>Nd>Y>Gd>Pr>Sm>Dy>Er>Yb>Ho>Eu>Tb>Lu>Tm. Some of the <span class="hlt">elements</span>, such as Sm, Dy, Ho, Er, Yb in the ash samples were in normal or nearly normal distribution, but Y, La, Ce, Pr, Nd, Eu, Gd, Tb, Tm, Lu were not normally distributed, indicating some of the ash samples were enriched with these <span class="hlt">elements</span>. Crust-normalized REE patterns indicated that two types of the MW ashes were obviously enriched with Gd and La. Sequential extraction results showed that REEs in the ash mainly presented as residual fraction, while exchangeable and carbonate fractions were relatively low. DTPA- and EDTA-extraction tests indicated that REEs in the MW ashes were generally in low bioavailability. PMID:18329796</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026144','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026144"><span id="translatedtitle">'Nano' Morphology and <span class="hlt">Element</span> Signatures of Early Life on <span class="hlt">Earth</span>: A New Tool for Assessing Biogenicity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oehler, D. Z.; Mostefaoui, S.; Meibom, A.; Selo, M.; McKay, D. S.; Robert, F.</p> <p>2006-01-01</p> <p>The relatively young technology of NanoSIMS is unlocking an exciting new level of information from organic matter in ancient sediments. We are using this technique to characterize Proterozoic organic material that is clearly biogenic as a guide for interpreting controversial organic structures in either terrestrial or extraterrestrial samples. NanoSIMS is secondary ion mass spectrometry for trace <span class="hlt">element</span> and isotope analysis at sub-micron resolution. In 2005, Robert et al. [1] combined NanoSIMS <span class="hlt">element</span> maps with optical microscopic imagery in an effort to develop a new method for assessing biogenicity of Precambrian structures. The ability of NanoSIMS to map simultaneously the distribution of organic <span class="hlt">elements</span> with a 50 nm spatial resolution provides new biologic markers that could help define the timing of life s development on <span class="hlt">Earth</span>. The current study corroborates the work of Robert et al. and builds on their study by using NanoSIMS to map C, N (as CN), S, Si and O of both excellently preserved microfossils and less well preserved, non-descript organics in Proterozoic chert from the ca. 0.8 Ga Bitter Springs Formation of Australia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MMTA..tmp..485R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MMTA..tmp..485R"><span id="translatedtitle">Grain Boundary Segregation of Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> in Magnesium Alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robson, Joseph D.; Haigh, Sarah J.; Davis, Bruce; Griffiths, David</p> <p>2015-10-01</p> <p>Small additions of rare-<span class="hlt">earth</span> (RE) <span class="hlt">elements</span> have been shown to have a powerful effect in modifying the texture of wrought magnesium alloys, giving a highly beneficial effect in improving their formability. Recent work has shown that segregation of RE atoms to grain boundaries is important in producing this texture change. In this work, two Mg-RE systems have been studied Mg-Y and Mg-Nd using high-resolution scanning transmission electron microscopy that permits both imaging and <span class="hlt">elemental</span> analysis with a spatial resolution of better than 0.1 nm. The Mg-Y alloy, where the solubility and level of addition are relatively high, showed the RE texture change effect. This was accompanied by clustering of Y on the grain boundaries, consistent with previous studies of the Mg-Gd system. The Mg-Nd alloy, where the solubility and level of addition are relatively low, showed no texture change and no segregation. In this case, impurity <span class="hlt">elements</span> binding the RE into insoluble particles, rendering it ineffective. The results are analyzed by modifying a previous model for the solute drag effect on boundaries expected due to the RE additions. This predicts that both Gd and Y will strongly inhibit boundary motion, with Gd being approximately twice as effective as Y.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.108...63P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.108...63P"><span id="translatedtitle">Insights into early <span class="hlt">Earth</span> from Barberton komatiites: Evidence from lithophile isotope and trace <span class="hlt">element</span> systematics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puchtel, I. S.; Blichert-Toft, J.; Touboul, M.; Walker, R. J.; Byerly, G. R.; Nisbet, E. G.; Anhaeusser, C. R.</p> <p>2013-05-01</p> <p>Major, minor, and lithophile trace <span class="hlt">element</span> abundances and Nd and Hf isotope systematics are reported for two sets of remarkably fresh, by Archean standards, samples of komatiitic lavas from the 3.48 Ga Komati and the 3.27 Ga Weltevreden Formations of the Barberton Greenstone Belt (BGB) in South Africa. These data are used to place new constraints on the thermal history of the early Archean mantle, on the timing of its differentiation, and on the origin and chemical nature of early mantle reservoirs and their evolution through time. Projected moderate to strong depletions of highly incompatible lithophile trace <span class="hlt">elements</span> and water in the mantle sources of both komatiite systems, combined with the partitioning behavior of V during lava differentiation, are consistent with anhydrous conditions during generation of the komatiite magmas. Komati and Weltevreden lavas are inferred to have erupted with temperatures of ?1600 °C, and, thus, represent the hottest known lavas on <span class="hlt">Earth</span>. The calculated mantle potential temperatures of ?1800 °C for both komatiite systems are 150-200 °C higher than those of contemporary ambient mantle. Combined, these observations are consistent with the origin of these BGB komatiite magmas in mantle plumes in the lower mantle. New Sm-Nd and Lu-Hf isotopic data allow precise determination of initial ?143Nd = +0.46 ± 0.10 and +0.50 ± 0.11 and initial ?176Hf = +1.9 ± 0.3 and +4.7 ± 0.8 for the Komati and the Weltevreden system komatiites, respectively. These positive initial values reflect prior fractionation of Sm/Nd and Lu/Hf in the mantle early in <span class="hlt">Earth</span> history. Conversely, ?142Nd values are 0.0 ± 2.4 and +2.2 ± 4.1 for the Komati and the Weltevreden systems, respectively. These values overlap, within uncertainties, those of modern terrestrial rocks, thus, limiting the magnitudes of possible Sm/Nd fractionations generated by early <span class="hlt">Earth</span> processes in the sources of these rocks. Combined 142,143Nd and Hf isotope and lithophile trace <span class="hlt">element</span> systematics are consistent with formation and long-term isolation of deep-seated mantle domains with fractionated Sm/Nd and Lu/Hf at ca. 4400 Ma. These domains were likely generated as a result of crystallization of a primordial magma ocean, with Mg-perovskite and minor Ca-perovskite acting as fractionating phases. The inferred mantle domains were evidently mixed away by 2.7 Ga on the scale of mantle reservoirs sampled by late Archean komatiite lavas emplaced worldwide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22257887','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22257887"><span id="translatedtitle">Study on the electrochemical extraction of rare <span class="hlt">earth</span> <span class="hlt">elements</span> from FLINAK</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Long, Dewu; Huang, Wei; Jiang, Feng; Tian, Lifang; Li, Qingnuan</p> <p>2013-07-01</p> <p>Electrochemical behaviors of rare <span class="hlt">earth</span> <span class="hlt">elements</span>, such as NdF{sub 3}, GdF{sub 3}, SmF{sub 3}, YF{sub 3}, and EuF{sub 3}, were investigated in a LiF-NaF-KF (46.5-11.5-42.0 mol %, FLINAK, m. p. 454 Celsius degrees) solvent. The results indicated that it is possible to extract Nd, Gd and Y directly by electrochemical deposition since the reductions of those cations to metal are located in the electrochemical window of the FLINAK eutectic, while the reductions of Sm and Eu metal are out of the range of the medium. Subsequently electro-deposition of Nd was carried out with two kinds of cathodic materials, namely, an inert cathode, Pt, and a reactive electrode, Cu. The collected products were characterized by various techniques revealing that a Nd-rich product was obtained. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/792697','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/792697"><span id="translatedtitle">Behavior of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> In Geothermal Systems; A New Exploration/Exploitation Tool</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scott A. Wood</p> <p>2002-01-28</p> <p>The goal of this four-year project was to provide a database by which to judge the utility of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in the exploration for and exploitation of geothermal fields in the United States. Geothermal fluids from hot springs and wells have been sampled from a number of locations, including: (1) the North Island of New Zealand (1 set of samples); (2) the Cascades of Oregon; (3) the Harney, Alvord Desert and Owyhee geothermal areas of Oregon; (4) the Dixie Valley and Beowawe fields in Nevada; (5) Palinpion, the Philippines: (6) the Salton Sea and Heber geothermal fields of southern California; and (7) the Dieng field in Central Java, Indonesia. We have analyzed the samples from all fields for REE except the last two.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24385183','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24385183"><span id="translatedtitle">Origin of middle rare <span class="hlt">earth</span> <span class="hlt">element</span> enrichment in acid mine drainage-impacted areas.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grawunder, Anja; Merten, Dirk; Büchel, Georg</p> <p>2014-01-01</p> <p>The commonly observed enrichment of middle rare <span class="hlt">earth</span> <span class="hlt">elements</span> (MREE) in water sampled in acid mine drainage (AMD)-impacted areas was found to be the result of preferential release from the widespread mineral pyrite (FeS2). Three different mining-impacted sites in Europe were sampled for water, and various pyrite samples were used in batch experiments with diluted sulphuric acid simulating AMD-impacted water with high sulphate concentration and high acidity. All water samples independent on their origin from groundwater, creek water or lake water as well as on the surrounding rock types showed MREE enrichment. Also the pyrite samples showed MREE enrichment in the respective acidic leachate but not always in their total contents indicating a process-controlled release. It is discussed that most probably complexation to sulphite (SO3 (2-)) or another intermediate S-species during pyrite oxidation is the reason for the MREE enrichment in the normalized REE patterns. PMID:24385183</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAP...118o4902Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAP...118o4902Z"><span id="translatedtitle">Binary rare <span class="hlt">earth</span> <span class="hlt">element</span>-Ni/Co metallic glasses with distinct ?-relaxation behaviors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Z. G.; Wang, Z.; Wang, W. H.</p> <p>2015-10-01</p> <p>We report the formation of a series of rare <span class="hlt">earth</span> <span class="hlt">element</span> (RE)-Ni/Co binary metallic glasses (MGs) with unusual distinct ?-relaxation peak compared with that of most of the reported MGs which usually exhibit as an excess wing or a shoulder. The ?-relaxation behavior of RE-Ni/Co MGs is sensitive to the composition and the atomic radii of the RE and can be tuned through changing the fraction of RE-Ni (or Co) atomic pairs. The novel RE-Ni/Co MGs with distinct ?-relaxation can serve as model system to investigate the nature of the ?-relaxation as well as its relations with other physical and mechanical properties of MGs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730043515&hterms=element+iron&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Delement%2Biron','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730043515&hterms=element+iron&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Delement%2Biron"><span id="translatedtitle">Rare <span class="hlt">earths</span>, other trace <span class="hlt">elements</span> and iron in Luna 20 samples.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Helmke, P. A.; Blanchard, D. P.; Jacobs, J. W.; Haskin, L.; Haskin, A.</p> <p>1973-01-01</p> <p>The results of the analysis by neutron activation of six samples from the Luna 20 mission and one sample of less than 1 mm fines from Apollo 16 are reported. The concentrations of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in the samples of fines from Luna 20 and Apollo 16 are less than those found for corresponding materials from the mare areas but a negative Eu anomaly is still present. The concentrations of the REE in fines from Luna 20 are only about two-thirds as great as in the sample of Apollo 16 fines, but the concentration of Co, Sc and Cr are greater by factors ranging from 1.5 to 2.3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CRGeo.347..294H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CRGeo.347..294H"><span id="translatedtitle">Anthropogenic rare <span class="hlt">earth</span> <span class="hlt">element</span> fluxes into floodplains: Coupling between geochemical monitoring and hydrodynamic sediment transport modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hissler, Christophe; Hostache, Renaud; Iffly, Jean François; Pfister, Laurent; Stille, Peter</p> <p>2015-09-01</p> <p>As all rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have an increasingly important role in high tech industries, they are now recognized as emergent pollutants in river systems impacted by anthropogenic activity. Over the past 20 years, significant anthropogenic contributions were reported for Gd, La and Sm, and we may expect that REE contamination in rivers is to further increase in a near future. Despite the work done to assess the environmental impact of REE pollutions in larger river systems, we are still lacking information on the dynamics of these anthropogenic compounds in relation to hydrological changes. Here, we observed for the first time particulate Ce originating from local industrial activities in Luxembourg and we quantified the anthropogenic contribution to the REE fluxes at the river basin scale during a single flood event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16038502','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16038502"><span id="translatedtitle">X-ray fluorescence analysis of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in rocks using low dilution glass beads.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakayama, Kenichi; Nakamura, Toshihiro</p> <p>2005-07-01</p> <p>Major and trace <span class="hlt">elements</span> (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, Fe, Rb, Sr, Y, Zr, La, Ce, Pr, Nd, Sm, Gd, Dy, Th and U) in igneous rocks were assayed with fused lithium borate glass beads using X-ray fluorescence spectrometry. Low dilution glass beads, which had a 1:1 sample-to-flux ratio, were prepared for determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Complete vitrification of 1:1 mixture required heating twice at 1200 degrees C with agitation. Extra pure reagents containing determinants were used for calibrating standards instead of the rock standard. The calibration curves of the 23 <span class="hlt">elements</span> showed good linearity. Furthermore, the lower limits of detection corresponding to three times the standard deviation for blank measurements were 26 mass ppm for Na2O, 6.7 for MgO, 4.5 for Al2O3, 4.5 for SiO2, 18 for P2O5, 1.1 for K2O, 4.0 for CaO, 3.9 for TiO2, 1.6 for MnO, 0.8 for Fe2O3, 0.5 for Rb, 0.2 for Sr, 0.4 for Y, 0.5 for Zr, 3.3 for La, 6.5 for Ce, 2.7 for Pr, 2.1 for Nd, 1.7 for Sm, 0.7 for Gd, 2.7 for Dy, 0.5 for Th, and 0.6 for U. Using the present method, we determined the contents of these 23 <span class="hlt">elements</span> in four rhyolitic and granitic rocks from Japan. PMID:16038502</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21324705','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21324705"><span id="translatedtitle">Natural radioactivity and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in feldspar samples, Central Eastern desert, Egypt.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Walley El-Dine, Nadia; El-Shershaby, Amal; Afifi, Sofia; Sroor, Amany; Samir, Eman</p> <p>2011-05-01</p> <p>The pegmatite bodies of the Eastern Desert of Egypt are widely distributed especially along the Marsa-Alam-Idfu road. The Abu Dob area covers about 150km(2) of the Arabian Nubian shield at the central part of the Eastern Desert of Egypt. Most of the pegmatite is zoned; the zonation starts with milky quartz at the core followed by alkali feldspar at the margins. The feldspars vary in color from rose to milky and in composition from K-feldspar to Na-feldspar, sometimes interactions of both types are encountered. Thirteen feldspar samples were collected from different locations in the Abu Dob area for measuring the natural radioactivity of (238)U, (232)Th and (40)K using an HPGe detector. The variation in concentration of radionuclides for the area under investigation can be classified into regions of high, medium and low natural radioactivity. The average concentration in BqKg(-1) has been observed to be from 9.5 to 183675.7BqKg(-1) for (238)U, between 6.1 and 94,314.2BqKg(-1) for (232)Th and from 0 to 7894.6BqKg(-1) for (40)K. Radium equivalent activities (Ra(eq)), dose rate (D(R)) and external hazard (H(ex)) have also been determined. In the present work, the concentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span> are measured for two feldspar samples using two techniques, Environmental Scanning Electron microscope XIL 30 ESEM, Philips, and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The existence of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in this area are very high and can be used in different important industries. PMID:21324705</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.S41A2162T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.S41A2162T"><span id="translatedtitle">Determination of <span class="hlt">Earth</span> structure using waveform inversion and Spectral-<span class="hlt">Element</span> Method for Eastern Asian region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsuboi, S.; Obayashi, M.; Tono, Y.; Suetsugu, D.</p> <p>2011-12-01</p> <p>Recent progress in large scale computing by using Spectral-<span class="hlt">Element</span> Method and the <span class="hlt">Earth</span> Simulator has demonstrated possibilities to perform full-waveform inversion of three dimensional (3D) seismic velocity structure inside the <span class="hlt">Earth</span>. Specifically Liu and Tromp (2006) have shown that it becomes feasible to compute finite frequency kernel for seismic velocity structure based on adjoint method. We apply their method to obtain 3D velocity structure beneath East Asia. We take one chunk from global mesh of Spectral-<span class="hlt">Element</span> Method and compute synthetic seismograms with accuracy of about 10 second. We use GAP-P2 mantle tomography model (Obayashi et al., 2009) as an initial 3D model and try to use as many broadband seismic stations available in this region, including Ocean Bottom Seismographs deployed in Philippine sea, as possible to perform inversion. We calculate synthetic seismograms for this initial 3D model and source receiver pairs. We then use the time windows for P and S waves to compute adjoint sources and calculate misfit adjoint kernels for seismic velocity structure. The kernels are calculated for all the time windows of P and S waves simultaneously. We sum up the event misfit kernels and perform the first iteration to improve the initial velocity model using the steepest decent method. The results of the first iteration shows that the differences between the initial model and the improved model is less than 1%, which shows that the modification resulted from the first iteration was quite modest. However the modifications to the initial model show different pattern among P-waves and S-waves, which implies that the scaling relation to obtain S-waves velocity model from P-wave velocity model might be revised in this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MinDe.tmp...43S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinDe.tmp...43S"><span id="translatedtitle">Geology and market-dependent significance of rare <span class="hlt">earth</span> <span class="hlt">element</span> resources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simandl, G. J.</p> <p>2014-09-01</p> <p>China started to produce rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MinDe..49..889S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinDe..49..889S"><span id="translatedtitle">Geology and market-dependent significance of rare <span class="hlt">earth</span> <span class="hlt">element</span> resources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simandl, G. J.</p> <p>2014-12-01</p> <p>China started to produce rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare <span class="hlt">earth</span> <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70044201','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70044201"><span id="translatedtitle">A major light rare-<span class="hlt">earth</span> <span class="hlt">element</span> (LREE) resource in the Khanneshin carbonatite complex, southern Afghanistan</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Horton, Forrest; Buttleman, Kim; Scott, Emily R.</p> <p>2012-01-01</p> <p>The rapid rise in world demand for the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) has expanded the search for new REE resources. We document two types of light rare-<span class="hlt">earth</span> <span class="hlt">element</span> (LREE)-enriched rocks in the Khanneshin carbonatite complex of southern Afghanistan: type 1 concordant seams of khanneshite-(Ce), synchysite-(Ce), and parisite-(Ce) within banded barite-strontianite alvikite, and type 2 igneous dikes of coarse-grained carbonatite, enriched in fluorine or phosphorus, containing idiomorphic crystals of khanneshite-(Ce) or carbocernaite. Type 1 mineralized barite-strontianite alvikite averages 22.25 wt % BaO, 4.27 wt % SrO, and 3.25 wt % ? LREE2O3 (sum of La, Ce, Pr, and Nd oxides). Type 2 igneous dikes average 14.51 wt % BaO, 5.96 wt % SrO, and 3.77 wt % ? LREE2O3. A magmatic origin is clearly indicated for the type 2 LREE-enriched dikes, and type 1 LREE mineralization probably formed in the presence of LREE-rich hydrothermal fluid. Both types of LREE mineralization may be penecontemporaneous, having formed in a carbonate-rich magma in the marginal zone of the central vent, highly charged with volatile constituents (i.e., CO2, F, P2O5), and strongly enriched in Ba, Sr, and the LREE. Based on several assumptions, and employing simple geometry for the zone of LREE enrichment, we estimate that at least 1.29 Mt (million metric tonnes) of LREE2O3 is present in this part of the Khanneshin carbonatite complex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22337283','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22337283"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> components in atmospheric particulates in the Bayan Obo mine region</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, Lingqing Liang, Tao Zhang, Qian; Li, Kexin</p> <p>2014-05-01</p> <p>The Bayan Obo mine, located in Inner Mongolia, China, is the largest light rare <span class="hlt">earth</span> body ever found in the world. The research for rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) enrichment in atmospheric particulates caused by mining and ore processing is fairly limited so far. In this paper, atmospheric particulates including total suspended particulate (TSP) matter and particles with an equivalent aerodynamic diameter less than 10 ?m (PM{sub 10}) were collected around the Bayan Obo mine region, in August 2012 and March 2013, to analyze the levels and distributions of REEs in particles. The total concentrations of REEs for TSP were 149.8 and 239.6 ng/m{sup 3}, and those for PM{sub 10} were 42.8 and 68.9 ng/m{sup 3}, in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM{sub 10} and the results indicated that REEs enrichment in atmosphere particulates was caused by anthropogenic sources and influenced by the strong wind in springtime. The spatial distribution of REEs in TSP showed a strong gradient concentration in the prevailing wind direction. REE chondrite normalized patterns of TSP and PM{sub 10} were similar and the normalized curves inclined to the right side, showing the conspicuous fractionation between the light REEs and heavy REE, which supported by the chondrite normalized concentration ratios calculated for selected <span class="hlt">elements</span> (La{sub N}/Yb{sub N}, La{sub N}/Sm{sub N}, Gd{sub N}/Yb{sub N}). - Highlights: • TSP and PM{sub 10} samples were collected to analyze the levels and distributions of REE. • Enrichment factors indicated that REE enrichment was caused by anthropogenic sources. • The distribution of REEs showed a strong gradient in the prevailing wind direction. • Obvious fractionation between LREEs and HREEs is observed in atmospheric particulates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMPP31C2047C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMPP31C2047C"><span id="translatedtitle">Planktonic foraminiferal rare <span class="hlt">earth</span> <span class="hlt">elements</span> as a potential new aeolian dust proxy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chou, C.; Liu, Y.; Lo, L.; Wei, K.; Shen, C.</p> <p>2012-12-01</p> <p>Characteristics of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have widely been used as important tracers in many fields of <span class="hlt">earth</span> 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 ?m) 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 ?18O 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4393457','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4393457"><span id="translatedtitle">A New Fungal Isolate, Penidiella sp. Strain T9, Accumulates the Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Dysprosium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Horiike, Takumi</p> <p>2015-01-01</p> <p>With an aim to develop a highly efficient method for the recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) by using microorganisms, we attempted to isolate dysprosium (Dy)-accumulating microorganisms that grow under acidic conditions from environmental samples containing high concentrations of heavy metals. One acidophilic strain, T9, which was isolated from an abandoned mine, decreased the concentration of Dy in medium that contained 100 mg/liter Dy to 53 mg/liter Dy after 3 days of cultivation at pH 2.5. The Dy content in the cell pellet of the T9 strain was 910 ?g/mg of dry cells. The T9 strain also accumulated other REEs. Based on the results of 28S-D1/D2 rRNA gene sequencing and morphological characterization, we designated this fungal strain Penidiella sp. T9. Bioaccumulation of Dy was observed on the cell surface of the T9 strain by <span class="hlt">elemental</span> mapping using scanning electron microscopy-energy dispersive X-ray spectroscopy. Our results indicate that Penidiella sp. T9 has the potential to recover REEs such as Dy from mine drainage and industrial liquid waste under acidic conditions. PMID:25710372</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25710372','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25710372"><span id="translatedtitle">A new fungal isolate, Penidiella sp. strain T9, accumulates the rare <span class="hlt">earth</span> <span class="hlt">element</span> dysprosium.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Horiike, Takumi; Yamashita, Mitsuo</p> <p>2015-05-01</p> <p>With an aim to develop a highly efficient method for the recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) by using microorganisms, we attempted to isolate dysprosium (Dy)-accumulating microorganisms that grow under acidic conditions from environmental samples containing high concentrations of heavy metals. One acidophilic strain, T9, which was isolated from an abandoned mine, decreased the concentration of Dy in medium that contained 100 mg/liter Dy to 53 mg/liter Dy after 3 days of cultivation at pH 2.5. The Dy content in the cell pellet of the T9 strain was 910 ?g/mg of dry cells. The T9 strain also accumulated other REEs. Based on the results of 28S-D1/D2 rRNA gene sequencing and morphological characterization, we designated this fungal strain Penidiella sp. T9. Bioaccumulation of Dy was observed on the cell surface of the T9 strain by <span class="hlt">elemental</span> mapping using scanning electron microscopy-energy dispersive X-ray spectroscopy. Our results indicate that Penidiella sp. T9 has the potential to recover REEs such as Dy from mine drainage and industrial liquid waste under acidic conditions. PMID:25710372</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NIMPB.366..184C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NIMPB.366..184C"><span id="translatedtitle">Study of K?2 /K?1 RYIED in closed and open shell Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chaves, P. C.; Tribolet, A. D.; Reis, M. A.</p> <p>2016-01-01</p> <p>Relative Yield Ion Energy Dependence (RYIED) was observed, named and reported as phenomenological evidence in 2005 (Reis et al., 2005). Since then, it was observed in transitions to the same subshell, and plausible explanations for the physics behind the phenomena have been proposed. In this work we present experimental evidence of the RYIED effect on the most inner transition possible in two Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE), namely variations in the intensity ratio of K?2 /K?1 X-rays from Tm and Yb irradiated under different conditions. These REE are particularly interesting to start with since Yb has an electronic configuration where all the subshells are completely filled, whilst Tm misses one electron in the 4f subshell. Ultrapure oxides of each <span class="hlt">element</span> were irradiated using proton beams having energies in the range of 0.9-3.6 MeV, in steps of 100 keV. Spectra were collected using the CdTe detector of the HRHE-PIXE set-up of C2TN and analysed using the DT2 code. Finally, the vanishing of the effect upon charging up of the target has been observed and will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983AcSpe..38..165B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983AcSpe..38..165B"><span id="translatedtitle">The determination of scandium, yttrium, and selected rare <span class="hlt">earth</span> <span class="hlt">elements</span> in geological materials by inductively coupled plasma optical emission spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bolton, Alexander; Hwang, Jack; Voet, Anthony Vander</p> <p></p> <p>The spectroscopic determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE's) in geological matrices is generally complicated by the relatively low concentrations of these <span class="hlt">elements</span>, the high concentrations or matrix <span class="hlt">elements</span> and their interferences in the analyte determination and a lack of well-defined usable concentration values for reference rock materials, especially at low REE concentrations. This paper describes work being carried out at the Geoscience Laboratories, Ontario Geological Survey, on the determination of Sc, Y, and selected rare <span class="hlt">earth</span> <span class="hlt">elements</span> at both high concentration and chondrite levels by inductively coupled plasma optical emission spectrometry. Direct acid digestate solutions (for high concentrations) and ion exchange separated solutions (for chondrite levels) are analyzed by a multichannel ICP spectrometer system: typical results for reference standards and samples are presented and compared.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1112002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1112002M"><span id="translatedtitle">Using rare <span class="hlt">earth</span> <span class="hlt">elements</span> for the identification of the geographic origin of food</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meisel, T.; Bandoniene, D.; Joebstl, D.</p> <p>2009-04-01</p> <p>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 <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">element</span> and rare <span class="hlt">earth</span> 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 <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V13G..02M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V13G..02M"><span id="translatedtitle">Linking rare <span class="hlt">earth</span> <span class="hlt">element</span> zoning in major and accessory minerals to better understand metasedimentary migmatites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matthews, J. A.; Kelly, N. M.; Koenig, A.; Harley, S. L.</p> <p>2011-12-01</p> <p>Trace <span class="hlt">element</span> signatures from major and accessory minerals are increasingly used to place constraints on the ages of tectonothermal events and gain insights into processes operating in the deep continental crust. Minerals such as garnet, zircon or monazite represent sensitive recorders of events if a solid understanding exists of what trace <span class="hlt">element</span> signatures represent. A study underway on granulite facies migmatites is providing insights into trace <span class="hlt">element</span> signatures in garnet, and when integrated with in situ, microbeam analysis of zircon and monazite, is allowing a complex polymetamorphic history to be deciphered. The Larsemann Hills, east Antarctica, are composed of felsic orthogneisses and metasediments that were affected by high-grade metamorphism and partial melting at c. 7 kbar and >800 °C. Initially interpreted to have experienced a single cycle of metamorphism at c. 550-530 Ma, recent ages suggest that the area was affected by an earlier high-grade event at c. 900 Ma; the timing of migmatization relative to these two events remains uncertain. To address this, a detailed study has targeted metasedimentary migmatites. Garnet, zircon and monazite were analysed from melanosome, leucosome and selvage domains. Garnet (predominantly almandine-pyrope) preserves little, if any, major <span class="hlt">element</span> zoning. In contrast, it records systematic within-grain variations in heavy rare <span class="hlt">earth</span> <span class="hlt">element</span> (HREE) concentration depending on textural context. Garnet within residuum domains displays broad cores with flat HREE slopes in chondrite-normalized plots, but are HREE-depleted (negative slopes) at boundaries adjacent to leucosome. In contrast, garnet boundaries adjacent to cordierite-rich selvages are typically HREE-enriched, with positive-sloping patterns. It is interpreted that core-rim depletions in HREE may reflect evolution of the whole-rock reservoir towards depletion during migmatization and garnet growth. Enrichment in garnet HREE adjacent to selvage domains likely resulted from local reaction between solids and melts either during melt transit and/or crystallization. Monazite, which is preferentially located in leucosome domains, preserves ages that reflect growth at c. 900 Ma and c. 530 Ma, although trace <span class="hlt">element</span> signatures are ambiguous. However, zircon, which is preferentially located in selvage domains, preserves c. 530 Ma rims with depleted, flat to negatively sloping HREE patterns. It is interpreted that these zircon rims grew in, or near to equilibrium with garnet cores and rims during partial melting, and may date at least part of migmatite formation in the Larsemann Hills. They do not date the final crystallization of melts and development of selvage domains. Preliminary results of this study have shown that the trace <span class="hlt">element</span> composition of garnet from high-temperature terrains can be a powerful tool in tracking metamorphic and melting processes where major <span class="hlt">elements</span> zoning is no longer preserved. This study also demonstrates the utility of textural context when interpreting trace <span class="hlt">element</span> patterns and ages from dateable accessory minerals in rocks from polycyclic metamorphic terrains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712017H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712017H"><span id="translatedtitle">Bioavailable concentrations of germanium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil fractions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hentschel, Werner; Wiche, Oliver</p> <p>2015-04-01</p> <p>As there is an increasing demand for germanium and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> due to their diverse application in modern technologies (optical cables, permanent magnets in wind power stations), there is an interest to investigate a new approach to extract these ubiquitous but disperse existing <span class="hlt">elements</span> - via Phytomining. But before this method can be established, a thorough understanding of processes regarding the intake of germanium (Ge) and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) is necessary. The aim of this work was to get insights or hints on correlations between the concentrations and the fractionation of Ge and REEs in the soil and the concentrations in plants - in other words we wanted to conduct research on bioavailable concentrations of Ge and REEs in soil fractions. On 18 sites situated around Freiberg, Saxony we took samples of soil and plants. To extract the <span class="hlt">elements</span> from the plant material a decomposition with hydrofluoric acid was used. The soil samples was examined by a sequential extraction with seven steps (mobile, carbonatic, oxidisable, amorphic oxides, crystalline oxides, phytoliths and secondary clay minerals, residual or siliceous). The amounts of the REEs showed a high correlation between each other, so neodymium can be regarded as a proxy for all REEs. The average total amount of Ge in the soil samples was around 1.45 mg/kg, the one of neodymium (Nd) was around 25 mg/kg. Both values equal the overall average in the <span class="hlt">earth</span> crust. Concerning the Ge concentration in soil the residual siliceous fractions constituted for 70% of total, whereas the fractions V and VI - dedicated as crystalline oxides and phytoliths/secondary clay minerals - made out for 25%. Only 5% of the total amount of Ge in soil accounted for the fractions I to IV. There was found a statistical significant correlation between the absolute Ge concentrations in these latter soil fractions with the Ge concentration in plant material of the same site. Therefore it seems that the fractions I to IV could be regarded as a proxy for the bioavailable pool of Ge in soils. Concerning Nd the residual siliceous fractions made out for 60% of the total, whereas the fraction III (oxidisable) constitutes for 30%. The remaining 10% accounted for the other soil fractions. No correlation between the concentration in one soil fraction and the concentration in plant material from the same site could be found. There was also no correlation between the total amount in soil and the concentration in plant material from the same site neither for the REEs nor for Ge. These results can give only hints on the processes regarding the mobilisation of the bioavailable pool of Ge and REEs. Further investigations are necessary and will be taken in the PhytoGerm project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010CoMP..160..761O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010CoMP..160..761O"><span id="translatedtitle">Rare <span class="hlt">earth</span> and high field strength <span class="hlt">element</span> partitioning between iron-rich clinopyroxenes and felsic liquids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olin, P. H.; Wolff, J. A.</p> <p>2010-11-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> are commonly assumed to substitute only for Ca in clinopyroxene because of the similarity of ionic radii for REE3+ and Ca2+ in eightfold coordination. The assumption is valid for Mg-rich clinopyroxenes for which observed mineral/melt partition coefficients are readily predicted by the lattice strain model for substitution onto a single site (e.g., Wood and Blundy 1997). We show that natural Fe-rich pyroxenes in both silica-undersaturated and silica-oversaturated magmatic systems deviate from this behavior. Salites (Mg# 48-59) in phonolites from Tenerife, ferrohedenbergites (Mg# 14.2-16.2) from the rhyolitic Bandelier Tuff, and ferroaugites (Mg# 9.6-32) from the rhyolitic Rattlesnake Tuff have higher heavy REE contents than predicted by single-site substitution. The ionic radius of Fe2+ in sixfold coordination is substantially greater than that of Mg2+; hence, we propose that, in Fe-rich clinopyroxenes, heavy REE are significantly partitioned between eightfold Ca sites and sixfold Fe and Mg sites such that Yb and Lu exist dominantly in sixfold coordination. We also outline a REE-based method of identifying pyroxene/melt pairs in systems with multiple liquid and crystal populations, based upon the assumption that LREE and MREE reside exclusively in eightfold coordination in pyroxene. Contrary to expectations, interpolation of mineral/melt partition coefficient data for heavy REE does not predict the behavior of Y. We speculate that mass fractionation effects play a role in mineral/melt lithophile trace <span class="hlt">element</span> partitioning that is detectable among pairs of isovalent <span class="hlt">elements</span> with near-identical radii, such as Y and Ho, Zr and Hf, and Nb and Ta.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23978671','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23978671"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs): effects on germination and growth of selected crop and native plant species.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thomas, Philippe J; Carpenter, David; Boutin, Céline; Allison, Jane E</p> <p>2014-02-01</p> <p>The phytotoxicity of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) is still poorly understood. The exposure-response relationships of three native Canadian plant species (common milkweed, Asclepias syriaca L., showy ticktrefoil, Desmodium canadense (L.) DC. and switchgrass, Panicum virgatum L.) and two commonly used crop species (radish, Raphanus sativus L., and tomato, Solanum lycopersicum L.) to the REEs lanthanum (La), yttrium (Y) and cerium (Ce) were tested. In separate experiments, seven to eight doses of each <span class="hlt">element</span> were added to the soil prior to sowing seeds. Effects of REE dose on germination were established through measures of total percent germination and speed of germination; effects on growth were established through determination of above ground biomass. Ce was also tested at two pH levels and plant tissue analysis was conducted on pooled samples. Effects on germination were mostly observed with Ce at low pH. However, effects on growth were more pronounced, with detectable inhibition concentrations causing 10% and 25% reductions in biomass for the two native forb species (A. syriaca and D. canadense) with all REEs and on all species tested with Ce in both soil pH treatments. Concentration of Ce in aboveground biomass was lower than root Ce content, and followed the dose-response trend. From values measured in natural soils around the world, our results continue to support the notion that REEs are of limited toxicity and not considered extremely hazardous to the environment. However, in areas where REE contamination is likely, the slow accumulation of these <span class="hlt">elements</span> in the environment could become problematic. PMID:23978671</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996CoMP..123..251P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996CoMP..123..251P"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> mobility during prograde granulite facies metamorphism: significance of fluorine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pan, Y.; Fleet, Michael E.</p> <p>1996-04-01</p> <p>Mafic gneisses occur as lenses or thin layers in spatial association with tonalitic leucosomes in a granulite zone of the Quetico subprovince of the Superior Province, Ontario, Canada, and exhibit concentric zoning with a biotite-rich margin, orthopyroxene-rich outer zone, clinopyroxene-rich central zone, and, occasionally, patches of relict amphibolites within the clinopyroxene-rich zone. The granulites (biotite-, orthopyroxene- and clinopyroxene-rich zones) in the mafic gneisses are characterized by significant amounts of rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE)-bearing fluorapatite (1 10 vol.%) and other REE-rich minerals (allanite, monazite and zircon). Fluorapatite shows an increase in modal abundance from the biotite- and orthopyroxene-rich zones to the clinopyroxene-rich zone, but is rare in the relict amphibolites. Textural evidence and <span class="hlt">element</span> partitioning indicate that fluorapatite (and other REE-rich minerals) was part of the peak metamorphic assemblages. Whole-rock geochemical analyses confirm that the granulites in the mafic gneisses contain anomalously high contents of REE and high field strength <span class="hlt">elements</span> (HFSE), whereas the relict amphibolites are geochemically typical of tholeiitic basalts. Mass-balance calculations reveal that REE and HFSE were introduced into the mafic gneisses during the prograde granulite facies metamorphism, pointing to REE mobility under granulite facies metamorphic conditions. The presence of high F contents in the REE-rich minerals and their associated minerals (e.g. biotite and hornblende) suggests that REE and HFSE may have been transported as fluoride complexes during the granulite facies metamorphism. This conclusion is supported by previously published results of hydrothermal experiments on the partitioning of REE between fluorapatite and F-rich fluids at 700°C and 2 kbar.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://mysite.science.uottawa.ca/khattori/Takahashi-REE-bacteria-Adsorption-Chem-Geol.pdf','EPRINT'); return false;" href="http://mysite.science.uottawa.ca/khattori/Takahashi-REE-bacteria-Adsorption-Chem-Geol.pdf"><span id="translatedtitle">Adsorption of rare <span class="hlt">earth</span> <span class="hlt">elements</span> onto bacterial cell walls and its implication for REE sorption onto natural microbial mats</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Hattori, Kéiko H.</p> <p></p> <p>Adsorption of rare <span class="hlt">earth</span> <span class="hlt">elements</span> onto bacterial cell walls and its implication for REE sorption Received 8 May 2004; received in revised form 7 January 2005; accepted 15 February 2005 Abstract Adsorption. The occurrence of M-type tetrad effect suggests that REE form inner sphere complexes during their adsorption onto</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=271700','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=271700"><span id="translatedtitle">Using Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> (REE) tracers to identify perferential micro-sites of post-fire aeolian erosion</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Plant communities in desert environments are spatially anisotropic. We applied Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> (REE) tracers to different landscape positions of an anisotropic Northern Chihuahua Desert ecosystem in an effort to study preferential sediment source areas. We delineated three 0.5 m by 6 m plots of...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70009869','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70009869"><span id="translatedtitle">A chemical-spectrochemical method for the determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and thorium in cerium minerals</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rose, H.J., Jr.; Murata, K.J.; Carron, M.K.</p> <p>1954-01-01</p> <p>In a combined chemical-spectrochemical procedure for quantitatively determining rare <span class="hlt">earth</span> <span class="hlt">elements</span> in cerium minerals, cerium is determined volumetrically, a total rare <span class="hlt">earths</span> plus thoria precipitate is separated chemically, the ceria content of the precipitate is raised to 80??0 percent by adding pure ceria, and the resulting mixture is analyzed for lanthanum, praseodymium, neodymium, samarium, gadolinium, yttrium, and thorium spectrochemically by means of the d.c. carbon arc. Spectral lines of singly ionized cerium are used as internal standard lines in the spectrochemical determination which is patterned after Fassel's procedure [1]. Results of testing the method with synthetic mixtures of rare <span class="hlt">earths</span> and with samples of chemically analyzed cerium minerals show that the coefficient of variation for a quadruplicate determination of any <span class="hlt">element</span> does not exceed 5??0 (excepting yttrium at concentrations less than 1 percent) and that the method is free of serious systematic error. ?? 1954.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26PSL.398..101T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.398..101T"><span id="translatedtitle">Efficient mobilization and fractionation of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> by aqueous fluids upon slab dehydration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsay, A.; Zajacz, Z.; Sanchez-Valle, C.</p> <p>2014-07-01</p> <p>The characteristic REE fractionation pattern in arc magmas compared to MOR-basalts results from the selective mobilization of light rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (LREE) by slab-derived mobile components. However, the nature and composition of the slab flux, and the actual mechanisms responsible for the transfer of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) from the slab to the mantle wedge remain unclear. We present experimental data on the solubility of selected REE in ligand-bearing aqueous fluids and a hydrous haplogranitic melt at 2.6 GPa and 600-800 °C, spanning the conditions relevant to slab dehydration and melting. The solubilities of REE in aqueous fluids increase more than an order of magnitude with temperature increasing from 600 to 800 °C. Addition of ligands such as Cl-, F-, CO32-, SO42- in relatively small concentrations (0.3-1.5 m [mol/kg H2O]) has a pronounced effect further enhancing REE solubilities. Each ligand yields a characteristic REE pattern by preferential dissolution of either the light or the heavy REE. For example, the addition of NaCl to the aqueous fluids yields highly elevated LREE/HREE ratios (La/Yb=17.4±4.3), whereas the addition of fluoride and sulfate ligands significantly increases the solubility of all REE with moderate LREE/HREE fractionation (La/Yb?4). The addition of Na2CO3 results in preferential increase of HREE solubilities, and yields La/Yb ratio of 1.6±0.5 by flattening the moderately fractionated REE pattern seen in pure aqueous fluids. The solubilities in hydrous haplogranite melt are moderate in comparison to those observed in aqueous fluids and do not lead to pronounced REE fractionation. Therefore, REE can be effectively mobilized and fractionated by aqueous fluids, compared to felsic hydrous melts. Furthermore, the aqueous fluid chemistry has a major role in determining REE mobilities and fractionation upon slab dehydration in addition to the significant control exerted by temperature. Our results show that chloride-bearing slab-derived aqueous fluids have a significant contribution to the formation of REE-signatures in arc-magmas, especially at lower slab surface temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1615804M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615804M"><span id="translatedtitle">Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> enrichment of Pacific seafloor sediments: the view from volcanic islands of Polynesia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Melleton, Jérémie; Tuduri, Johann; Pourret, Olivier; Bailly, Laurent; Gisbert, Thierry</p> <p>2014-05-01</p> <p>Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are key metals for «green» technologies such as energy saving lamps or permanent magnets used in, e.g., wind turbines, hard disk drives, portable phone or electric or hybrid vehicles. Since several years, world demand for these metals is therefore drastically increasing. The quasi-monopolistic position of China, which produces around 95 % of global REEs production, generates risks for the industries that depend on a secure supply of REEs. In response, countries are developing and diversifying their supply sources, with new mining projects located outside China and efforts in the area of REEs recycling. Most of these projects focus on deposits related to carbonatites and alkaline-peralkaline magmatism, which are generally enriched in light REEs (LREEs) compared to the heavy REEs (HREEs)-enriched deposits of the ion-adsorption types, located in southern China. However, a recent study revealed new valuable resources corresponding to seafloor sediments located in the south-eastern and north-central Pacific. The deep-sea mud described by these authors show a higher HREE/LREE ratio than ion-adsorption deposits, a feature which significantly increases their economic interest. The authors suggest mid-ocean ridge hydrothermal activity as an explanation to this anomalous enrichment. However, several contributions have documented considerable REEs enrichment in basalts and peridotitic xenoliths from French Polynesia. Several arguments have been exposed in favour of a supergene origin, with a short migration, suggesting that REEs were collected from weathered basalts. The Tahaa volcanic island (Sous-le-Vent Island, Society Archipelago, French Polynesia) is the first location where such enrichment has been described. New petrographic and mineralogical investigations confirm a supergene mobilization of this abnormal occurrence. REE-bearing minerals (mainly phosphates of the rhabdophane group) are primarily located within basalt vesicles but also in crack that cross-cut the calcite filling the vesicles or the volcanic glass. They are also closely associated with Ni-Mg bearing phyllosilicates, which appear to nucleate from alteration of olivine and clinopyroxenes. Further investigations are done to evidence and confirm an anterior magmatic enrichment. On the basis of these observations, we believe that the anomalous enrichment observed in seafloor sediments could derive from abnormally-rich provinces corresponding to aerial basaltic formations from oceanic islands primarily enriched during weathering processes (Melleton et al., 2014). Melleton et al. (2014). Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> enrichment of Pacific sea-floor sediments: the view from volcanic islands of Polynesia. In preparation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ag.udel.edu/soilchem/Sparks05GES7.pdf','EPRINT'); return false;" href="http://ag.udel.edu/soilchem/Sparks05GES7.pdf"><span id="translatedtitle">Seventh International Symposium on the <span class="hlt">Geochemistry</span> of the <span class="hlt">Earth</span>'s Surface GES-7, Aix-en-Provence, August 23-27, 2005, France</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Sparks, Donald L.</p> <p></p> <p>of reactions at biological, chemica/, and physical interfaces, and the use of advanced in situ technologies and abstruse portion of the entire <span class="hlt">Earth</span> (NRC, 2001). If we are going to sustain the planet for human, chemical transformations, toxicity, bioavailability, and ultimate impacts on human health; mechanisms</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013652','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013652"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the phosphatic-enriched sediment of the Peru shelf</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Piper, D.Z.; Baedecker, P.A.; Crock, J.G.; Burnett, W.C.; Loebner, B.J.</p> <p>1988-01-01</p> <p>Apatite-enriched materials from the Peru shelf have been analyzed for their major oxide and rare <span class="hlt">earth</span> <span class="hlt">element</span> (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 <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25679485','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25679485"><span id="translatedtitle">Health effects and toxicity mechanisms of rare <span class="hlt">earth</span> <span class="hlt">elements</span>-Knowledge gaps and research prospects.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pagano, Giovanni; Guida, Marco; Tommasi, Franca; Oral, Rahime</p> <p>2015-05-01</p> <p>In the recent decades, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">elements</span>. 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. PMID:25679485</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1191943-utilizing-rare-earth-elements-tracers-high-tds-reservoir-brines-ccs-applications','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1191943-utilizing-rare-earth-elements-tracers-high-tds-reservoir-brines-ccs-applications"><span id="translatedtitle">Utilizing rare <span class="hlt">earth</span> <span class="hlt">elements</span> as tracers in high TDS reservoir brines in CCS applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGESBeta</a></p> <p>McLing, Travis; Smith, William; Smith, Robert</p> <p>2014-12-31</p> <p>In this paper we report the result of research associated with the testing of a procedures necessary for utilizing natural occurring trace <span class="hlt">elements</span>, specifically the Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) as geochemical tracers in Carbon Capture and Storage (CCS) applications. Trace <span class="hlt">elements</span>, particularly REE may be well suited to serve as in situ tracers for monitoring geochemical conditions and the migration of CO?-charged waters within CCS storage systems. We have been conducting studies to determine the efficacy of using REE as a tracer and characterization tool in the laboratory, at a CCS analogue site in Soda Springs, Idaho, and at amore »proposed CCS reservoir at the Rock Springs Uplift, Wyoming. Results from field and laboratory studies have been encouraging and show that REE may be an effective tracer in CCS systems and overlying aquifers. In recent years, a series of studies using REE as a natural groundwater tracer have been conducted successfully at various locations around the globe. Additionally, REE and other trace <span class="hlt">elements</span> have been successfully used as in situ tracers to describe the evolution of deep sedimentary Basins. Our goal has been to establish naturally occurring REE as a useful monitoring measuring and verification (MMV) tool in CCS research because formation brine chemistry will be particularly sensitive to changes in local equilibrium caused by the addition of large volumes of CO?. Because brine within CCS target formations will have been in chemical equilibrium with the host rocks for millions of years, the addition of large volumes of CO? will cause reactions in the formation that will drive changes to the brine chemistry due to the pH change caused by the formation of carbonic acid. This CO? driven change in formation fluid chemistry will have a major impact on water rock reaction equilibrium in the formation, which will impart a change in the REE fingerprint of the brine that can measured and be used to monitor in situ reservoir conditions. Our research has shown that the REE signature imparted to the formation fluid by the introduction of CO? to the formation, can be measured and tracked as part of an MMV program. Additionally, this REE fingerprint may serve as an ideal tracer for fluid migration, both within the CCS target formation, and should formation fluids migrate into overlying aquifers. However application of REE and other trace <span class="hlt">elements</span> to CCS system is complicated by the high salt content of the brines contained within the target formations. In the United States by regulation, in order for a geologic reservoir to be considered suitable for carbon storage, it must contain formation brine with total dissolved solids (TDS) > 10,000 ppm, and in most cases formation brines have TDS well in excess of that threshold. The high salinity of these brines creates analytical problems for <span class="hlt">elemental</span> analysis, including <span class="hlt">element</span> interference with trace metals in Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) (i.e. <span class="hlt">element</span> mass overlap due to oxide or plasma phenomenon). Additionally, instruments like the ICP-MS that are sensitive enough to measure trace <span class="hlt">elements</span> down to the parts per trillion level are quickly oversaturated when water TDS exceeds much more than 1,000 ppm. Normally this problem is dealt with through dilution of the sample, bringing the water chemistry into the instruments working range. However, dilution is not an option when analyzing these formation brines for trace metals, because trace <span class="hlt">elements</span>, specifically the REE, which occur in aqueous solutions at the parts per trillion levels. Any dilution of the sample would make REE detection impossible. Therefore, the ability to use trace metals as in situ natural tracers in high TDS brines environments requires the development of methods for pre-concentrating trace <span class="hlt">elements</span>, while reducing the salinity and associated <span class="hlt">elemental</span> interference such that the brines can be routinely analyzed by standard ICP-MS methods. As part of the Big Sky Carbon Sequestration Project the INL-CAES has developed a rapid, easy to use proces</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1191943','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1191943"><span id="translatedtitle">Utilizing rare <span class="hlt">earth</span> <span class="hlt">elements</span> as tracers in high TDS reservoir brines in CCS applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McLing, Travis; Smith, William; Smith, Robert</p> <p>2014-12-31</p> <p>In this paper we report the result of research associated with the testing of a procedures necessary for utilizing natural occurring trace <span class="hlt">elements</span>, specifically the Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) as geochemical tracers in Carbon Capture and Storage (CCS) applications. Trace <span class="hlt">elements</span>, particularly REE may be well suited to serve as <i>in situ</i> tracers for monitoring geochemical conditions and the migration of CO?-charged waters within CCS storage systems. We have been conducting studies to determine the efficacy of using REE as a tracer and characterization tool in the laboratory, at a CCS analogue site in Soda Springs, Idaho, and at a proposed CCS reservoir at the Rock Springs Uplift, Wyoming. Results from field and laboratory studies have been encouraging and show that REE may be an effective tracer in CCS systems and overlying aquifers. In recent years, a series of studies using REE as a natural groundwater tracer have been conducted successfully at various locations around the globe. Additionally, REE and other trace <span class="hlt">elements</span> have been successfully used as <i>in situ</i> tracers to describe the evolution of deep sedimentary Basins. Our goal has been to establish naturally occurring REE as a useful monitoring measuring and verification (MMV) tool in CCS research because formation brine chemistry will be particularly sensitive to changes in local equilibrium caused by the addition of large volumes of CO?. Because brine within CCS target formations will have been in chemical equilibrium with the host rocks for millions of years, the addition of large volumes of CO? will cause reactions in the formation that will drive changes to the brine chemistry due to the pH change caused by the formation of carbonic acid. This CO? driven change in formation fluid chemistry will have a major impact on water rock reaction equilibrium in the formation, which will impart a change in the REE fingerprint of the brine that can measured and be used to monitor <i>in situ</i> reservoir conditions. Our research has shown that the REE signature imparted to the formation fluid by the introduction of CO? to the formation, can be measured and tracked as part of an MMV program. Additionally, this REE fingerprint may serve as an ideal tracer for fluid migration, both within the CCS target formation, and should formation fluids migrate into overlying aquifers. However application of REE and other trace <span class="hlt">elements</span> to CCS system is complicated by the high salt content of the brines contained within the target formations. In the United States by regulation, in order for a geologic reservoir to be considered suitable for carbon storage, it must contain formation brine with total dissolved solids (TDS) > 10,000 ppm, and in most cases formation brines have TDS well in excess of that threshold. The high salinity of these brines creates analytical problems for <span class="hlt">elemental</span> analysis, including <span class="hlt">element</span> interference with trace metals in Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) (i.e. <span class="hlt">element</span> mass overlap due to oxide or plasma phenomenon). Additionally, instruments like the ICP-MS that are sensitive enough to measure trace <span class="hlt">elements</span> down to the parts per trillion level are quickly oversaturated when water TDS exceeds much more than 1,000 ppm. Normally this problem is dealt with through dilution of the sample, bringing the water chemistry into the instruments working range. However, dilution is not an option when analyzing these formation brines for trace metals, because trace <span class="hlt">elements</span>, specifically the REE, which occur in aqueous solutions at the parts per trillion levels. Any dilution of the sample would make REE detection impossible. Therefore, the ability to use trace metals as <i>in situ</i> natural tracers in high TDS brines environments requires the development of methods for pre-concentrating trace <span class="hlt">elements</span>, while reducing the salinity and associated <span class="hlt">elemental</span> interference such that the brines can be routinely analyzed by standard ICP-MS methods. As part of the Big Sky Carbon Sequestration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8862736','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8862736"><span id="translatedtitle">Concentration of rare <span class="hlt">earth</span> <span class="hlt">elements</span>, As, and Th in human brain and brain tumors, determined by neutron activation analysis.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhuang, G; Zhou, Y; Lu, H; Lu, W; Zhou, M; Wang, Y; Tan, M</p> <p>1996-01-01</p> <p>Toxic <span class="hlt">elements</span> As and Th, six rare-<span class="hlt">earth</span> <span class="hlt">elemental</span> profiles of brain tumor tissues from 16 patients of astrocytomas (grade I-III), and normal human brain tissues of 18 male, age-matched autopsies serving as controls have been studied by radiochemical neutron activation analysis. P-204 [di(2-ethylhexyl) phosphate] extraction chromatography column was used for group separation of rare-<span class="hlt">earth</span> <span class="hlt">element</span> (REE) by one step. Compared with the normal brain tissues, the analytical results showed that the concentrations of Th, La, Ce, Gd, and Lu were significantly higher in tumor tissues (P < 0.01 or 0.001). The possible effects of REE on tumor cell were discussed. PMID:8862736</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710235D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710235D"><span id="translatedtitle">Developing alternative resources of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Europe - EURARE and the red mud challenge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deady, Eimear; Mouchos, Evangelos; Goodenough, Kathryn; Wall, Frances; Williamson, Ben</p> <p>2015-04-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are considered to be highly "critical" by the European Commission [1], owing to the concentration of global supply [2] and their use in a wide range of emerging technologies (e.g. smart phones, electric cars and wind turbines). The main source of REE is the mineral bastnäsite, which is primarily extracted from carbonatites. Alternative resources of REE have been identified in a variety of other environments such as alluvial placers, bauxites and ore tailings. The EURARE project (www.eurare.eu), funded by the European Commission, aims to improve understanding of potential REE resources in Europe with the overall objective of establishing the basis for a European REE industry. As a part of this project, alternative sources of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Europe are being considered. REE have been identified as being particularly enriched in karst-bauxites and hence in the red muds generated as a waste product from the processing of these bauxites to alumina through the Bayer process [3]. Karst-bauxites are widely distributed with deposits known across the Mediterranean and with intermittent exploitation occurring over many decades. REE become concentrated in the bauxite deposits by the bauxitisation process and are retained due to the geochemical barrier created by the limestone bedrock below. This can result in several processes, including the crystallisation of authigenic REE-bearing minerals, the accumulation of residual phases and the adsorption of ions onto clays and other mineral surfaces [4]. Red muds produced from alumina processing represent a potentially important concentration of REE as it has been demonstrated that the REE pass through the alumina extraction process into the waste, and the total REE concentrations are typically enriched by a factor of two compared with the original bauxite ore [5]. Bauxites and red muds from the Parnassus Ghiona region of Greece [6] and the Seydi?ehir-Akseki region of Turkey have been assessed as part of this study. Red muds from these deposits contain on average 900 ppm REE compared with typical values of <100 ppm to ~500 ppm REE in the bauxites. Extraction of REE from red muds has been shown to be feasible [5,7] although it is challenging due to the heterogeneous spatial distribution of REE in the primary bauxite deposits [8], an unclear understanding of the mobility of REE in red mud tailings ponds, and the need for development of appropriate processing methods. However, the resource potential of red muds in Europe is significant with approximately 3.5 Mt of bauxite ore extracted in 2012 [2], resulting in approximately 1.4 Mt of red mud from the production of alumina. In addition a large volume of stockpiled red muds exists from historical processing of bauxites, the total of which is not well constrained. Understanding the REE potential of both bauxites and red muds is integral to an assessment of European REE resources. References [1] European Commission, "Report on critical raw materials for the EU. Report of the Ad hoc Working Group on defining critical raw materials". May 2014. [2] T. Brown, N. Idoine, E. Raycraft, R. Shaw, E. Deady, J. Rippingale, T. Bide, C. Wrighton, J. Rodley, "World Mineral Production 2008-12" British Geological Survey, Keyworth, Nottingham, 2014. [3] Z. Maksimovi? and G. Pantó, "Authigenic rare <span class="hlt">earth</span> minerals in karst-bauxites and karstic nickel deposits". In: A.P. Jones, F. Wall and C.T. Williams, Rare <span class="hlt">earth</span> minerals, chemistry, origin and ore deposits, Chapter 10, pp. 257-279, 1996. [4] G. Bárdossy, "Karst Bauxites, Bauxite Deposits on Carbonate Rocks". Elsevier, 444pp, 1982. [5] M. Ochsenkühn-Petropoulou, T. Lyberopoulou, and G. Parissakis, "Direct determination of lanthanides, yttium and scandium in bauxites and red mud from alumina production", Analytica Chimica Acta, vol. 296, no. 3, pp. 305-313, October 1994. [6] É. Deady, E. Mouchos, K. Goodenough, B. Williamson and F. Wall. "Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Karst-Bauxites: a Novel Untapped European Resou</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712022W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712022W"><span id="translatedtitle">Assessment of Bioavailable Concentrations of Germanium and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in the Rhizosphere of White Lupin (Lupinus albus L.)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wiche, Oliver; Fischer, Ronny; Moschner, Christin; Székely, Balázs</p> <p>2015-04-01</p> <p>Concentrations of Germanium (Ge) and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in soils are estimated at 1.5 mg kg -1 (Ge), 25 mg kg -1 (La) and 20 mg kg -1 (Nd), which are only roughly smaller than concentrations of Pb and Zn. Germanium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> are thus not rare but widely dispersed in soils and therefore up to date, only a few minable deposits are available. An environmental friendly and cost-effective way for Ge and rare <span class="hlt">earth</span> <span class="hlt">element</span> production could be phytomining. However, the most challenging part of a phytomining of these <span class="hlt">elements</span> is to increase bioavailable concentrations of the <span class="hlt">elements</span> in soils. Recent studies show, that mixed cultures with white lupine or other species with a high potential to mobilize trace metals in their rhizosphere due to an acidification of the soil and release of organic acids in the root zone could be a promising tool for phytomining. Complexation of Ge and rare <span class="hlt">earth</span> <span class="hlt">elements</span> by organic acids might play a key role in controlling bioavailability to plants as re-adsorption on soil particles and precipitation is prevented and thus, concentrations in the root zone of white lupine increase. This may also allow the complexes to diffuse along a concentration gradient to the roots of mixed culture growing species leading to enhanced plant uptake. However, to optimize mixed cultures it would be interesting to know to which extend mobilization of trace metals is dependent from chemical speciation of <span class="hlt">elements</span> in soil due to the interspecific interaction of roots. A method for the identification of complexes of germanium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> with organic acids, predominantly citric acid in the rhizosphere of white lupine was developed and successfully tested. The method is based on coupling of liquid chromatography with ICP-MS using a zic-philic column (SeQuant). As a preliminary result, we were able to show that complexes of germanium with citric acid exist in the rhizosphere of white lupin, what may contribute to the bioavailability of this <span class="hlt">element</span>. These studies have been carried out in the framework of the PhytoGerm project, financed by the Federal Ministry of Education and Research, Germany. The authors are grateful to students and laboratory assistants contributing in the field work and sample preparation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AREPS..42..443Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AREPS..42..443Z"><span id="translatedtitle"><span class="hlt">Earth</span> Abides Arsenic Biotransformations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Yong-Guan; Yoshinaga, Masafumi; Zhao, Fang-Jie; Rosen, Barry P.</p> <p>2014-05-01</p> <p>Arsenic is the most prevalent environmental toxic <span class="hlt">element</span> and causes health problems throughout the world. The toxicity, mobility, and fate of arsenic in the environment are largely determined by its speciation, and arsenic speciation changes are driven, at least to some extent, by biological processes. In this article, biotransformation of arsenic is reviewed from the perspective of the formation of <span class="hlt">Earth</span> and the evolution of life, and the connection between arsenic <span class="hlt">geochemistry</span> and biology is described. The article provides a comprehensive overview of molecular mechanisms of arsenic redox and methylation cycles as well as other arsenic biotransformations. It also discusses the implications of arsenic biotransformation in environmental remediation and food safety, with particular emphasis on groundwater arsenic contamination and arsenic accumulation in rice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004Geo....32..497M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004Geo....32..497M"><span id="translatedtitle">Effect of paleosol formation on rare <span class="hlt">earth</span> <span class="hlt">element</span> signatures in fossil bone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Metzger, Christine A.; Terry, Dennis O., Jr.; Grandstaff, David E.</p> <p>2004-06-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) content of fossil bones was analyzed and compared with the degree of ancient pedogenic development and depositional environments from several locations in the Orellan Scenic Member of the Oligocene Brule Formation in Badlands National Park, South Dakota. Paleosols ranged from weakly developed Entisols to more strongly developed Inceptisols, all typical of fluvial environments and possible paleocatena variation. Paleosols were alkaline and well drained. Sediments with sparse soil features from an oxbow lake system suggest that conditions were too waterlogged and sedimentation rates too rapid for significant pedogenesis. The variance of REE signatures in fossil bones from the paleosol sites was significantly greater than that of fossils from minimally altered sediments of the former oxbow lake. Positive Ce anomalies were associated with low U concentrations and indicate paleoredox conditions. Greater degrees of pedogenesis, regardless of the horizon in which the bone was found, systematically correlated with increased heavy REE enrichment in fossil bones. The fossil-bone REE signatures from the different paleosols and depositional environments were significantly different and distinguishable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26107531','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26107531"><span id="translatedtitle">Selective Extraction of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> from Permanent Magnet Scraps with Membrane Solvent Extraction.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R</p> <p>2015-08-18</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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. PMID:26107531</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15285371','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15285371"><span id="translatedtitle">A method for predicting bioavailability of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soils to maize.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Wei-Sheng; Shan, Xiao-Quan; Wen, Bei; Zhang, Shu-Zhen</p> <p>2004-03-01</p> <p>A single-extraction procedure using low-molecular-weight organic acids (LMWOAs) as extractant and the first and second steps of a three-step extraction procedure recommended by the European Community Bureau of Reference (BCR; now European Community Standards, Measurement and Testing Programme, Brussels, Belgium) were performed to extract the light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREEs) La, Ce, Pr, and Nd from wet rhizosphere soil. The extracted soil solutions were successively filtered through membranes with a pore size of less than 0.45 microm and a molecular weight cutoff of less than 1 kDa, which were termed colloidal and truly dissolved fractions, respectively. Apoplastically and symplastically bound LREEs in maize roots were experimentally distinguished by ultrasound-assisted desorption with 1 mM CaCl2 solution at 0 degrees C in ice-cooled water bath. When the LMWOAs extraction method was used, a good correlation was obtained between LREEs in soil colloidal and truly dissolved fractions and LREEs bound to apoplasm and symplasm of maize root. Both apoplastically and symplastically bound LREEs are the result of bioavailability. However, a poor correlation was obtained between LREEs in fractions water soluble, exchangeable and carbonate bound (B1) and Fe-Mn oxide bound (B2) of the BCR method and LREEs in apoplasm and symplasm and in intact roots. Hence, the LMWOAs extraction method is recommended for measuring the bioavailability of LREEs in soils. PMID:15285371</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24972173','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24972173"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> distributions and fractionation in plankton from the northwestern Mediterranean Sea.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Strady, Emilie; Kim, Intae; Radakovitch, Olivier; Kim, Guebuem</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations were measured for the first time in plankton from the northwestern Mediterranean Sea. The REE concentrations in phytoplankton (60-200 ?m) were 5-15 times higher than those in four size fractions of zooplankton: 200-500 ?m, 500-1000 ?m, 1000-2000 ?m and >2000 ?m. The concentrations within these zooplankton fractions exhibited the same ranges with some variation attributed to differences in zooplankton taxonomy. The REE concentrations in plankton were poorly related to the reported REE concentrations of seawater, but they correlated well with the calculated REE(3+), concentrations especially with regard to middle REE (MREEs) and heavy REEs (HREEs). Plankton and seawater revealed different PAAS-normalised REE distributions, with the greatest differences observed in the light REEs. Interestingly, a comparison of PAAS-normalized sediment particles from the study of Fowler et al. (1992) showed concentrations of the same order of magnitude and a similar REE distribution without MREE enrichment. Based on this comparison, we propose a conceptual model that emphasizes the importance of biological scavenging of REEs (especially LREEs) in surface waters. PMID:24972173</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25920439','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25920439"><span id="translatedtitle">Determination of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Hypersaline Solutions Using Low-Volume, Liquid-Liquid Extraction.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Noack, Clinton W; Dzombak, David A; Karamalidis, Athanasios K</p> <p>2015-08-18</p> <p>Complex, hypersaline brines-including those coproduced with oil and gas, rejected from desalination technologies, or used as working fluids for geothermal electricity generation-could contain critical materials such as the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in valuable concentrations. Accurate quantitation of these analytes in complex, aqueous matrices is necessary for evaluation and implementation of systems aimed at recovering those critical materials. However, most analytical methods for measuring trace metals have not been validated for highly saline and/or chemically complex brines. Here we modified and optimized previously published liquid-liquid extraction (LLE) techniques using bis(2-ethylhexyl) phosphate as the extractant in a heptane diluent, and studied its efficacy for REE recovery as a function of three primary variables: background salinity (as NaCl), concentration of a competing species (here Fe), and concentration of dissolved organic carbon (DOC). Results showed that the modified LLE was robust to a range of salinity, Fe, and DOC concentrations studied as well as constant, elevated Ba concentrations. With proper characterization of the natural samples of interest, this method could be deployed for accurate analysis of REE in small volumes of hyper-saline and chemically complex brines. PMID:25920439</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7302586','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7302586"><span id="translatedtitle">Cerium redox cycles and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Sargasso Sea</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sholkovitz, E.R.; Schneider, D.L. )</p> <p>1991-10-01</p> <p>Two profiles of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are reported for the upper water column of the Sargasso Sea. The trivalent-only REEs have remarkably constant concentrations in the upper 500m of an April 1989 profile and in the upper 200m of a May 1989 profile. In contrast, Ce concentrations decrease smoothly with increasing depth. In April 1989 Ce decreases from 15.7 pmol/kg at 20 m to 5.1 pmol/kg at 750 m. Cerium, which has Redox transformations in seawater, behaves anomalously with respect to its REE(III) neighbors. While both dissolved Ce and Mn have elevated concentrations in the upper 200m, their vertical gradients are distinctly different. In contrast to Mn, which reaches a minimum dissolved concentration near the zone (150-250 m) of a particulate Mn maximum, Ce is being removed both near this zone and to depths of at least 750m. These new profiles indicate that Ce is involved in an upper ocean redox cycle. This interpretation is consistent with the MOFFETT (1990) incubation tracer experiments on the same May 1989 seawater. He showed that Ce(III) oxidation is biologically mediated, probably light inhibited, increases with depth, and 3-4 times slower than Mn(II) oxidation in the 100-200 m zone. CERoclines provide new information into the fine scale zonation of redox process operating in the upper columns of oligotrophic oceans.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26141170','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26141170"><span id="translatedtitle">Template polymerization synthesis of hydrogel and silica composite for sorption of some rare <span class="hlt">earth</span> <span class="hlt">elements</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Borai, E H; Hamed, M G; El-kamash, A M; Siyam, T; El-Sayed, G O</p> <p>2015-10-15</p> <p>New sorbents containing 2-acrylamido 2-methyl propane sulphonic acid monomer onto poly(vinyl pyrilidone) P(VP-AMPS) hydrogel and P(VP-AMPS-SiO2) composite have been synthesized by radiation template polymerization. The effect of absorbed dose rate (kGy), crosslinker concentration and polymer/monomer ratio on the degree of template polymerization of P(VP-AMPS) hydrogel was studied. The degree of polymerization was evaluated by the calculated percent conversion and swelling degree. The maximum capacity of P(VP-AMPS) hydrogel toward Cu(+2) metal ion found to be 91 mg/gm. The polymeric composite P(VP-AMPS-SiO2) has been successfully synthesized. The structure of the prepared hydrogel and composite were confirmed by FTIR, thermal analysis (TGA and DTA) and SEM micrograph. Batch adsorption studies for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(+2) metal ions on the prepared hydrogel and composite were investigated as a function of shaking time, pH and metal ion concentration. The sorption efficiency of the prepared hydrogel and composite toward light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREEs) are arranged in the order La(3+)>Ce(3+)>Nd(3+)>Eu(3+). The obtained results demonstrated the superior adsorption capacity of the composite over the polymeric hydrogel. The maximum capacity of the polymeric composite was found to be 116, 103, 92, 76, 74 mg/gm for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(2+) metal ions respectively. PMID:26141170</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014731','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014731"><span id="translatedtitle">Determination of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in geological materials by inductively coupled plasma mass spectrometry</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lichte, F.E.; Meier, A.L.; Crock, J.G.</p> <p>1987-01-01</p> <p>A method of analysis of geological materials for the determination of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> using the Inductively coupled plasma mass spectrometric technique (ICP-MS) has been developed. Instrumental parameters and factors affecting analytical results have been first studied and then optimized. Samples are analyzed directly following an acid digestion, without the need for separation or preconcentration with limits of detection of 2-11 ng/g, precision of ?? 2.5% relative standard deviation, and accuracy comparable to inductively coupled plasma emission spectrometry and instrumental neutron activation analysis. A commercially available ICP-MS instrument is used with modifications to the sample introduction system, torch, and sampler orifice to reduce the effects of high salt content of sample solutions prepared from geologic materials. Corrections for isobaric interferences from oxide ions and other diatomic and triatomic ions are made mathematically. Special internal standard procedures are used to compensate for drift in metahmetal oxide ratios and sensitivity. Reference standard values are used to verify the accuracy and utility of the method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25000508','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25000508"><span id="translatedtitle">Examination of rare <span class="hlt">earth</span> <span class="hlt">element</span> concentration patterns in freshwater fish tissues.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayfield, David B; Fairbrother, Anne</p> <p>2015-02-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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 (?REE) 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. PMID:25000508</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750051000&hterms=Yttrium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DYttrium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750051000&hterms=Yttrium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DYttrium"><span id="translatedtitle">Fractionation in the solar nebula - Condensation of yttrium and the rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Boynton, W. V.</p> <p>1975-01-01</p> <p>The condensation of Y and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25894494','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25894494"><span id="translatedtitle">Red Phosphorus: An <span class="hlt">Earth</span>-Abundant <span class="hlt">Elemental</span> Photocatalyst for "Green" Bacterial Inactivation under Visible Light.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xia, Dehua; Shen, Zhurui; Huang, Guocheng; Wang, Wanjun; Yu, Jimmy C; Wong, Po Keung</p> <p>2015-05-19</p> <p><span class="hlt">Earth</span>-abundant red phosphorus was found to exhibit remarkable efficiency to inactivate Escherichia coli K-12 under the full spectrum of visible light and even sunlight. The reactive oxygen species (•OH, •O2(-), H2O2), which were measured and identified to derive mainly from photogenerated electrons in the conduction band using fluorescent probes and scavengers, collectively contributed to the good performance of red phosphorus. Especially, the inactivated-membrane function enzymes were found to be associated with great loss of respiratory and ATP synthesis activity, the kinetics of which paralleled cell death and occurred much earlier than those of cytoplasmic proteins and chromosomal DNA. This indicated that the cell membrane was a vital first target for reactive oxygen species oxidation. The increased permeability of the cell membrane consequently accelerated intracellular protein carboxylation and DNA degradation to cause definite bacterial death. Microscopic analyses further confirmed the cell destruction process starting with the cell envelope and extending to the intracellular components. The red phosphorus still maintained good performance even after recycling through five reaction cycles. This work offers new insight into the exploration and use of an <span class="hlt">elemental</span> photocatalyst for "green" environmental applications. PMID:25894494</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MSMSE..21f5003F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MSMSE..21f5003F"><span id="translatedtitle">Gupta potential for rare <span class="hlt">earth</span> <span class="hlt">elements</span> of the fcc phase: lanthanum and cerium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fu, Jie; Zhao, Jijun</p> <p>2013-09-01</p> <p>The potential parameters for a Gupta-type many-body potential are fitted for the first two rare <span class="hlt">earth</span> <span class="hlt">elements</span>, La and Ce. The experimental cohesive energies, lattice parameters and elastic constants of ?-La and ?-Ce solids of the face-centered cubic (fcc) phase are well reproduced. The theoretical P-V curves, sound velocities and Debye temperatures of ?-La and ?-Ce solids are in reasonable agreement with experimental data. The vacancy formation energies and surface energies are also predicted. In particular, the phonon dispersion relationship and vibrational frequencies at high symmetric points within the first Brillouin zone from our potential are consistent with experimental ones. Molecular dynamics simulation are performed to determine the melting temperature of La and Ce solids as well as the radial distribution function of liquid La, which are also in line with experimental data. All these agreements indicate the validity of the current set of potential parameters. Thus, the Gupta potential developed here would be useful in future simulation of La, Ce solids and their alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4586675','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4586675"><span id="translatedtitle">Remediation of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Pollutants by Sorption Process Using Organic Natural Sorbents</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Butnariu, Monica; Negrea, Petru; Lupa, Lavinia; Ciopec, Mihaela; Negrea, Adina; Pentea, Marius; Sarac, Ionut; Samfira, Ionel</p> <p>2015-01-01</p> <p>The effects of the sorption of environmental applications by various source materials of natural organic matter, i.e., bone powder, was examined. Sorption capacities and subsequent rare <span class="hlt">earth</span> <span class="hlt">element</span> retention characteristics of all metals tested were markedly increased by ionic task-specific. In this study, the abilities of three models’ isotherms widely were used for the equilibrium sorption data: Langmuir, Freundlich and Redlich-Peterson. For all studied metal ions the maximum adsorption capacity is close to those experimentally determined. The characteristic parameters for each isotherm and related coefficients of determination have been determined. The experimental data achieved excellent fits within the following isotherms in the order: Langmuir > Redlich-Peterson > Freundlich, based on their coefficient of determination values. The bone powder has developed higher adsorption performance in the removal process of Nd(III), Eu(III), La(III) from aqueous solutions than in the case of the removal process of Cs(I), Sr(II) and Tl(I) from aqueous solutions. The described relationships provide direct experimental evidence that the sorption-desorption properties of bone powder are closely related to their degree of the type of the metal. The results suggest a potential for obtaining efficient and cost-effective engineered natural organic sorbents for environmental applications. PMID:26378553</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19770064910&hterms=Rare+earth+metals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528%2528Rare%2Bearth%2529%2Bmetals%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770064910&hterms=Rare+earth+metals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528%2528Rare%2Bearth%2529%2Bmetals%2529"><span id="translatedtitle">Composition and evolution of the eucrite parent body - Evidence from rare <span class="hlt">earth</span> <span class="hlt">elements</span>. [extraterrestrial basaltic melts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Consolmagno, G. J.; Drake, M. J.</p> <p>1977-01-01</p> <p>Quantitative modeling of the evolution of rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) abundances in the eucrites, which are plagioclase-pigeonite basalt achondrites, indicates that the main group of eucrites (e.g., Juvinas) might have been produced by approximately 10% equilibrium partial melting of a single type of source region with initial REE abundances which were chondritic relative and absolute. Since the age of the eucrites is about equal to that of the solar system, extensive chemical differentiation of the eucrite parent body prior to the formation of eucrites seems unlikely. If homogeneous accretion is assumed, the bulk composition of the eucrite parent body can be estimated; two estimates are provided, representing different hypotheses as to the ratio of metal to olivine in the parent body. Since a large number of differentiated olivine meteorites, which would represent material from the interior of the parent body, have not been detected, the eucrite parent body is thought to be intact. It is suggested that the asteroid 4 Vesta is the eucrite parent body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26378553','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26378553"><span id="translatedtitle">Remediation of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Pollutants by Sorption Process Using Organic Natural Sorbents.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Butnariu, Monica; Negrea, Petru; Lupa, Lavinia; Ciopec, Mihaela; Negrea, Adina; Pentea, Marius; Sarac, Ionut; Samfira, Ionel</p> <p>2015-09-01</p> <p>The effects of the sorption of environmental applications by various source materials of natural organic matter, i.e., bone powder, was examined. Sorption capacities and subsequent rare <span class="hlt">earth</span> <span class="hlt">element</span> retention characteristics of all metals tested were markedly increased by ionic task-specific. In this study, the abilities of three models' isotherms widely were used for the equilibrium sorption data: Langmuir, Freundlich and Redlich-Peterson. For all studied metal ions the maximum adsorption capacity is close to those experimentally determined. The characteristic parameters for each isotherm and related coefficients of determination have been determined. The experimental data achieved excellent fits within the following isotherms in the order: Langmuir > Redlich-Peterson > Freundlich, based on their coefficient of determination values. The bone powder has developed higher adsorption performance in the removal process of Nd(III), Eu(III), La(III) from aqueous solutions than in the case of the removal process of Cs(I), Sr(II) and Tl(I) from aqueous solutions. The described relationships provide direct experimental evidence that the sorption-desorption properties of bone powder are closely related to their degree of the type of the metal. The results suggest a potential for obtaining efficient and cost-effective engineered natural organic sorbents for environmental applications. PMID:26378553</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvL.111x2502G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvL.111x2502G"><span id="translatedtitle">New Fission Fragment Distributions and r-Process Origin of the Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goriely, S.; Sida, J.-L.; Lemaître, J.-F.; Panebianco, S.; Dubray, N.; Hilaire, S.; Bauswein, A.; Janka, H.-T.</p> <p>2013-12-01</p> <p>Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process <span class="hlt">elements</span> with nuclear mass numbers A?140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular, the fission fragment yields determine the creation of 110?A?170 nuclei. Here, we apply a new scission-point model, called SPY, to derive the fission fragment distribution (FFD) of all relevant neutron-rich, fissioning nuclei. The model predicts a doubly asymmetric FFD in the abundant A?278 mass region that is responsible for the final recycling of the fissioning material. Using ejecta conditions based on relativistic NS merger calculations, we show that this specific FFD leads to a production of the A?165 rare-<span class="hlt">earth</span> peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r nuclei with A?140.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24483647','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24483647"><span id="translatedtitle">New fission fragment distributions and r-process origin of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Goriely, S; Sida, J-L; Lemaître, J-F; Panebianco, S; Dubray, N; Hilaire, S; Bauswein, A; Janka, H-T</p> <p>2013-12-13</p> <p>Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process <span class="hlt">elements</span> with nuclear mass numbers A?140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular, the fission fragment yields determine the creation of 110?A?170 nuclei. Here, we apply a new scission-point model, called SPY, to derive the fission fragment distribution (FFD) of all relevant neutron-rich, fissioning nuclei. The model predicts a doubly asymmetric FFD in the abundant A?278 mass region that is responsible for the final recycling of the fissioning material. Using ejecta conditions based on relativistic NS merger calculations, we show that this specific FFD leads to a production of the A?165 rare-<span class="hlt">earth</span> peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r nuclei with A?140. PMID:24483647</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012626','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012626"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> distribution in some hydrothermal minerals: evidence for crystallographic control</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morgan, J.W.; Wandless, G.A.</p> <p>1980-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeCoA..66.1323D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeCoA..66.1323D"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the water column of Lake Vanda, McMurdo Dry Valleys, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Carlo, Eric Heinen; Green, William J.</p> <p>2002-04-01</p> <p>We present data on the composition of water from Lake Vanda, Antarctica. Vanda and other lakes in the McMurdo Dry Valleys of Antarctica are characterized by closed basins, permanent ice covers, and deep saline waters. The meromictic lakes provide model systems for the study of trace metal cycling owing to their pristine nature and the relative simplicity of their biogeochemical systems. Lake Vanda, in the Wright Valley, is supplied by a single input, the Onyx River, and has no output. Water input to the lake is balanced by sublimation of the nearly permanent ice cap that is broken only near the shoreline during the austral summer. The water column is characterized by an inverse thermal stratification of anoxic warm hypersaline water underlying cold oxic freshwater. Water collected under trace-<span class="hlt">element</span> clean conditions was analyzed for its dissolved and total rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations by inductively coupled plasma mass spectrometry. Depth profiles are characterized by low dissolved REE concentrations (La, Ce, <15 pM) in surface waters that increase slightly (La, 70 pM; Ce, 20 pM) with increasing depth to ˜55 m, the limit of the fresh oxic waters. Below this depth, a sharp increase in the concentrations of strictly trivalent REE (e.g., La, 5 nM) is observed, and a submaximum in redox sensitive Ce (2.6 nM) is found at 60- to 62-m depth. At a slightly deeper depth, a sharper Ce maximum is observed with concentrations exceeding 11 nM at a 67-m depth, immediately above the anoxic zone. The aquatic concentrations of REE reported here are ˜50-fold higher than previously reported for marine oxic/anoxic boundaries and are, to our knowledge, the highest ever observed at natural oxic/anoxic interfaces. REE maxima occur within stable and warm saline waters. All REE concentrations decrease sharply in the sulfidic bottom waters. The redox-cline in Lake Vanda is dominated by diffusional processes and vertical transport of dissolved species driven by concentration gradients. Furthermore, because the ultraoligotrophic nature of the lake limits the potential for organic phases to act as metal carriers, metal oxide coatings and sulfide phases appear to largely govern the distribution of trace <span class="hlt">elements</span>. We discuss REE cycling in relation to the roles of redox reactions and competitive scavenging onto Mn- and Fe-oxides coatings on clay sized particles in the upper oxic water column and their release by reductive dissolution near the anoxic/oxic interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6064212','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6064212"><span id="translatedtitle">Pacific ferromanganese crust geology and <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Andreev, S.I.; Vanstein, B.G.; Anikeeva, L.I. )</p> <p>1990-06-01</p> <p>Cobaltiferous ferromanganese crusts form part of a large series of oceanic ferromanganese oxide deposits. The crusts show high cobalt (commonly over 0.4%), low nickel and copper sum (0.4-0.8%), considerably high manganese (18-20%), and iron (14-18%). Less abundant <span class="hlt">elements</span> in crusts are represented by molybdenum and vanadium; the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> cerium, lanthenum, and yttrium; and the noble metals platinum and rhodium. Co-rich crusts form at water depths of 600 to 2,500 m. Crust thicknesses range from millimeters to 15-17 cm, averaging 2-6 cm. The most favorable conditions for 4-10 cm thick crusts to occur is at water depths of 1,200-2,200 m. The crusts formed on basaltic, calcareous, siliceous, and breccia bedrock surfaces provided there were conditions preventing bottom sedimentation at them. If the sedimentation takes place, it may be accompanied by nodules similar in composition to the crusts. The most favorable topography for extensive crust formation is considered to be subdued (up to 20{degree}) slopes and summit platforms of conical seamounts, frequently near faults and their intersection zones. Subhorizontal guyot summits do not usually favor crust growth. Crust <span class="hlt">geochemistry</span> is primarily defined by mineralogy and manganese hydroxides (vernadite)/iron ratio. The first associated group of compounds includes cobalt, nickel, molybdenum, vanadium, cerium, and titanium; the other is strontium, yttrium, cerium, and cadmium. The aluminosilicate phase is associated with titanium, iron, chromium, and vanadium; phosphate biogenic phase includes copper, nickel, zinc, lead, and barium. The crucial point in cobaltiferous crust formation is their growth rate on which is dependent the degree of ferromanganese matrix sorption saturation with cobalt. The optimum for cobalt-rich ferromanganese ores is the conditions facilitating long-term and continuous hydrogenic processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25269316','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25269316"><span id="translatedtitle">[Indirect determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Chinese herbal medicines by hydride generation-atomic fluorescence spectrometry].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zeng, Chao; Lu, Jian-Ping; Xue, Min-Hua; Tan, Fang-Wei; Wu, Xiao-Yan</p> <p>2014-07-01</p> <p>Based on their similarity in chemical properties, rare <span class="hlt">earth</span> <span class="hlt">elements</span> were able to form stable coordinated compounds with arsenazo III which were extractable into butanol in the presence of diphenylguanidine. The butanol was removed under reduced pressure distillation; the residue was dissolved with diluted hydrochloric acid. As was released with the assistance of KMnO4 and determined by hydrogen generation-atomic fluorescence spectrometry in terms of rare <span class="hlt">earth</span> <span class="hlt">elements</span>. When cesium sulfate worked as standard solution, extraction conditions, KMnO4 amount, distillation temperature, arsenazo III amount, interfering ions, etc were optimized. The accuracy and precision of the method were validated using national standard certified materials, showing a good agreement. Under optimum condition, the linear relationship located in 0.2-25 microg x mL(-1) and detection limit was 0.44 microg x mL(-1). After the herbal samples were digested with nitric acid and hydrogen peroxide, the rare <span class="hlt">earth</span> <span class="hlt">elements</span> were determined by this method, showing satisfactory results with relative standard deviation of 1.3%-2.5%, and recoveries of 94.4%-106.0%. The method showed the merits of convenience and rapidness, simple instrumentation and high accuracy. With the rare <span class="hlt">earths</span> enriched into organic phase, the separation of analytes from matrix was accomplished, which eliminated the interference. With the residue dissolved by diluted hydrochloric acid after the solvent was removed, aqueous sample introduction eliminated the impact of organic phase on the tubing connected to pneumatic pump. PMID:25269316</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012BGD.....9.3645B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012BGD.....9.3645B"><span id="translatedtitle">Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline <span class="hlt">earth</span> <span class="hlt">elements</span> as tracers of watershed hydrochemistry and provenance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.</p> <p>2012-03-01</p> <p>For reconstructing environmental change in terrestrial realms the <span class="hlt">geochemistry</span> of fossil bioapatite in bones and teeth is among the most promising applications. This study demonstrates that alkaline <span class="hlt">earth</span> <span class="hlt">elements</span> in enamel of Hippopotamids, in particular Ba and Sr are tracers for water provenance and hydrochemistry. The studied specimens are molar teeth from Hippopotamids found in modern and fossil lacustrine settings of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by ca. two orders of magnitude for Ba (120-9336 ?g g-1) as well as for Sr (9-2150 ?g g-1). Concentration variations in enamel are partly induced during post-mortem alteration and during amelogenesis, but the major contribution originates from the variable water chemistry in the habitats of the Hippopotamids which is dominated by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of Ba and Sr in modern and fossil enamel, in that <span class="hlt">element</span> concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.5. These <span class="hlt">elements</span> are well correlated with MgO and Na2O in single specimens, thus suggesting that their distribution is determined by a common, single process. Presuming that the shape of the tooth is established at the end of the secretion process and apatite composition is in equilibrium with the enamel fluid, the maturation process can be modeled by closed system Rayleigh crystallization. Enamel from many Hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores, but the compositions extend well into the levels of plants and carnivores. Within enamel from single specimens these <span class="hlt">element</span> ratios covary and provide a specific fingerprint of the Hippopotamid habitat. All specimens together, however, define subparallel trends with different Ba/Sr ranging from 0.1 to 3. This ratio varies on spatial and temporal scales and traces provenance signals as well as the fractionation of the <span class="hlt">elements</span> in the hydrological cycle. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic or Archean crustal rocks as the ultimate sources of Sr and Ba. The provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from about 2 to 0.5. This trend can be correlated with changes in climate from humid to arid in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that with time, Ba mobility decreased relative to that of Sr. This can arise if preferential adsorption of Ba to clay and Fe-oxide-hydroxide is related to increasing aridification. Additionally, weathering solutions and lake water can become increasingly alkaline and barite becomes stable. In this case, Ba will be preferentially deposited on the watershed of Lake Albert and rivers with low Ba/Sr will feed the habitats of the Hippopotamids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7182962','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7182962"><span id="translatedtitle">Ocean particle chemistry: The fractionation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> between suspended particles and seawater</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sholkovitz, E.R. ); Landing, W.M.; Lewis, B.L. )</p> <p>1994-03-01</p> <p>Sargasso Sea suspended particles were sequentially digested with three chemical treatments (acetic acid, mild HCl/HNO[sub 3], and HF/HNO[sub 3]/HCl in a bomb). The latter two treatments dissolve detrital minerals, while the acetic acid removes surface coatings (organic matter and Mn oxides). The rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) composition of the surface coatings, in marked contrast to the crust-like REE composition of the two detrital phases, is extensively fractionated with respect to both filtered seawater and the crust. Surface coatings are responsible for the removal and fractionation of REEs from seawater and, as such, play a key role in the marine geochemical cycles of trace <span class="hlt">elements</span>. Relative to seawater, the surface coatings are systematically enriched tenfold across the trivalent REEs from Lu to La and develop large positive Ce-anomalies. The Ce-anomalies of the coatings switch from being negative (seawater-like) in the upper 100 m to being strongly positive at greater depths. The ingrowth of Ce and LREEs on particle surfaces reflects the in situ oxidation of dissolved Ce(III) to particulate Ce(IV), and the preferential removal of LREE(III)s over HREE(III)s. REEs(III) fractionation of this type is consistent with particle/solution models. Both processes appear to be related to the in situ formation of Mn oxide particles from the oxidation of dissolved Mn(II) in the upper 200 m of the water column. Preferential removal of LREEs in the upper waters is countered by their preferential release at depth due to remineralization of surface coatings on particles. A new method is explored for estimating the residence time of suspended particles by combining Ce concentration data of dissolved and surface-bound phases with the Ce(III) oxidation rate measurements of MOFFETT (1990). A Ce-based residence time of thirteen days is similar in magnitude to the value calculated from U-[sup 234]Th disequilibria in the Sargasso Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7597Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7597Z"><span id="translatedtitle">Rare <span class="hlt">earth</span> and trace <span class="hlt">elements</span> of fossil vertebrate bioapatite as palaeoenvironmental and sedimentological proxies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Žigait?, Živil?; Fadel, Alexandre; Pérez-Huerta, Alberto; Jeffries, Teresa</p> <p>2015-04-01</p> <p>Rare <span class="hlt">earth</span> (REE) and trace <span class="hlt">element</span> 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 <span class="hlt">elemental</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.7103I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.7103I"><span id="translatedtitle">Geochemical characteristics of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soil of the Ditru Massif, Eastern Carpathians, Romania</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ion, Adriana</p> <p>2013-04-01</p> <p>The present paper describes the level of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soils developed from Ditr?u massif area for evaluating of the background of these <span class="hlt">elements</span> and accurate assessment of environmental impact. Also this paper contributed to understanding the important role of parent rocks in pedogenic processes. The Ditr?u Alkaline Massif represent an intrusion body with a internal zonal structure, which was emplaced into pre-Alpine metamorphic rocks of the Bucovinian nappe complex close the Neogene - Quaternary volcanic arc of the Calimani-Guurghiu- Harghita Mountain chain. The center of massif was formed by nepheline syenite, which is surrounded by syenite and monazonite. North-western and north-eastern marginal sectors are composed of hornblende gabbro/hornblendite, alkali diorite, monzodiorite, monzosyenites and alkali granite. Small discrete ultramafic bodies (kaersutite-bearing peridotite, olivine, pyroxenite and hornblendite) and alkali gabbros occur in the Jolotca area. All this rocks are cut by late-stage dykes with a large variety of composition including tinguaite, phonolite, nepheline syenite, microsyenite, and aplite. The types of soils predominant in this zone are lithosoils. These soils are shallow developed, have low content in organic matter and reflects mineralogical and geochemical composition of the bedrock. The soil samples were collected from 70 location for all type of representative rocks (approximately 10 soil sampling points for each type of rock). The samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The pH values of these samples varied from 3.6 to 7.3, in general, the soils from massif area are acid or weakly acidic. The pH controls the abundance of REE in soil, the concentration of REE increases with decreasing pH values. In soil samples analyzed the contents of REE follow the order: Ce > La > Nd > Pr > Sm > Eu > Gd > Dy > Yb > Er > Tb > Ho >Tm. ? REE varied from 52.59 ?g g-1 to 579.2 ?g g-1 , the average is 273.14 ?g g-1. The chemical analysis of soil showed an enrichment in LREE (from La to Eu) and a depletion in HREE (from Gd to Lu). Relatively high levels of LREE concentration in soil are genetically associated with REE mineralization. The soil samples developed on the syenite and nephelin syenite are enriched in HREE. The REE chondrite - normalized plots showed for most soils in the sampling area strongly negative anomalies for cerium and europium, positive anomalies for gadolinium and dysprosium. The distribution of REE in soil is given and controlled by the presence of primary minerals (potasic and plagioclase feldspars) and accessory minerals (zircon, monazite, titanite, allanite, apatite, xenotime, thorite, bastnäsite) in bedrock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090020501','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090020501"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Measurements of Melilite and Fassaite in Allende Cai by Nanosims</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ito, M.; Messenger, Scott</p> <p>2009-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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-<span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP51C1092D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP51C1092D"><span id="translatedtitle">Carbonatite: A Geophysical investigation of a rare <span class="hlt">earth</span> <span class="hlt">element</span> terrane, eastern Mojave Desert, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denton, K. M.; Ponce, D. A.; Miller, D. M.; MacPherson-Krutsky, C. C.</p> <p>2013-12-01</p> <p>Geophysical investigations reveal gravity and magnetic anomalies related to a Proterozoic carbonatite terrane in the eastern Mojave Desert, host to one of the largest rare <span class="hlt">earth</span> <span class="hlt">element</span> carbonatite deposits in the world. The deposit is located near Mountain Pass, California and occurs in a north-northwest trending fault-bounded block that extends along the eastern parts of the Clarke Mountain Range, Mescal Range, and Ivanpah Mountains. This Early to Middle Proterozoic block is composed of a 1.7 Ga metamorphic complex of gneiss and schist intruded by a 1.4 Ga suite of ultrapotassic alkaline intrusive rocks that includes carbonatite. The intrusive suite (oldest to youngest) includes shonkinite, mesosyenite, syenite, quartz syenite, potassic granite, carbonatite, and late shonkinite dikes which are spatially and temporally associated with carbonatite intrusions and dikes. Regional geophysical data reveal that the carbonatite deposit occurs along a gravity high and the northeast edge of a prominent magnetic high with an amplitude of about 200 nanoteslas. More than 1400 gravity stations and over 200 physical property samples were collected to augment existing geophysical data and will be used to determine the geophysical and geologic setting that provide an improved structural interpretation of the eastern Mojave Desert carbonatite terrane. Physical properties of representative rock types in the area include carbonatite ore, syenite, shonkinite, gneiss, granite, and dolomite. Carbonatite intrusions typically have distinctive gravity, magnetic, and radiometric signatures because these deposits are relatively dense, contain magnetite, and are enriched in thorium or uranium. However, our results show that the main carbonatite body is essentially nonmagnetic. Thus, it is unlikely that carbonatite rocks are the source of the magnetic high associated with the Clark Mountain and Mescal Ranges. Instead, we suggest that weakly to moderately magnetic intrusive rocks or crystalline basement are the source of the magnetic high.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20110012866&hterms=Sulfur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSulfur','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20110012866&hterms=Sulfur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSulfur"><span id="translatedtitle">The Formation of Sulfate and <span class="hlt">Elemental</span> Sulfur Aerosols Under Varying Laboratory Conditions: Implications for Early <span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DeWitt, H. Langley; Hasenkopf, Christa A.; Trainer, Melissa G.; Farmer, Delphine K.; Jimenez, Jose L.; McKay, Christopher P.; Toon, Owen B.; Tolbert, Margaret A.</p> <p>2010-01-01</p> <p>The presence of sulfur mass-independent fractionation (S-MIF) in sediments more than 2.45 x 10(exp 9) years old is thought to be evidence for an early anoxic atmosphere. Photolysis of sulfur dioxide (SO2) by UV light with lambda < 220 nm has been shown in models and some initial laboratory studies to create a S-MIF; however, sulfur must leave the atmosphere in at least two chemically different forms to preserve any S-MIF signature. Two commonly cited examples of chemically different sulfur species that could have exited the atmosphere are <span class="hlt">elemental</span> sulfur (S8) and sulfuric acid (H2S04) aerosols. Here, we use real-time aerosol mass spectrometry to directly detect the sulfur-containing aerosols formed when SO2 either photolyzes at wavelengths from 115 to 400 nm, to simulate the UV solar spectrum, or interacts with high-energy electrons, to simulate lightning. We found that sulfur-containing aerosols form under all laboratory conditions. Further, the addition of a reducing gas, in our experiments hydrogen (H2) or methane (CH4), increased the formation of S8. With UV photolysis, formation of S8 aerosols is highly dependent on the initial SO2 pressure; and S8 is only formed at a 2% SO2 mixing ratio and greater in the absence of a reductant, and at a 0.2% SO2 mixing ratio and greater in the presence of 1000 ppmv CH4. We also found that organosulfur compounds are formed from the photolysis of CH4 and moderate amounts of SO2, The implications for sulfur aerosols on early <span class="hlt">Earth</span> are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MinDe..49..967H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MinDe..49..967H"><span id="translatedtitle">The rare <span class="hlt">earth</span> <span class="hlt">element</span> potential of kaolin deposits in the Bohemian Massif (Czech Republic, Austria)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Höhn, S.; Frimmel, H. E.; Pašava, J.</p> <p>2014-12-01</p> <p>Four kaolin deposits in the Bohemian Massif were studied in order to assess the potential for the recovery of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) as by-products from the residue after extraction and refining of the raw kaolin. The behaviour of REE + Y during kaolinitization was found to be largely a function of pre-alteration mineralogy. In the examples studied, i.e. granite-derived deposits of Kriechbaum (Austria) and Boži?any, and arkose-derived deposits of Kazn?jov and Podbo?any (all Czech Republic), the REE + Y are predominantly hosted by monazite which has remained unaffected by kaolinitization. The overall REE + Y content of the variably kaolinitized rocks is strongly dependent on their genesis. While ion adsorption plays only a minor role in the concentration of REE + Y in the studied kaolinitized rocks, the processing and refining of the raw kaolin leads to residues that are enriched in REE + Y by a factor of up to 40. The use of a magnetic separator and a hydrocyclone in the processing of the raw material can yield REE + Y contents of as much as 0.77 wt%. Although this value compares well with the REE + Y concentration in some potentially economic REE + Y projects elsewhere, the overall tonnage of the (REE + Y)-enriched residue is by far not sufficient to consider economic extraction of REE + Y as by-product. Our results are most probably applicable also to other kaolin deposits derived from the weathering of Hercynian basement granites elsewhere (e.g. in Saxonia and Bavaria, Germany). Overall, the potential for REE + Y production as by-product from kaolin mining has to be regarded as minimal.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25957938','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25957938"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> and critical metal content of extracted landfilled material and potential recovery opportunities.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gutiérrez-Gutiérrez, Silvia C; Coulon, Frédéric; Jiang, Ying; Wagland, Stuart</p> <p>2015-08-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), Platinum group metals (PGMs) and other critical metals currently attract significant interest due to the high risks of supply shortage and substantial impact on the economy. Their uses in many applications have made them present in municipal solid waste (MSW) and in commercial and industrial waste (C&I), since several industrial processes produce by-products with high content of these metals. With over 4000 landfills in the UK alone, the aim of this study was to assess the existence of these critical metals within landfills. Samples collected from four closed landfills in UK were subjected to a two-step acid digestion to extract 27 metals of interest. Concentrations across the four landfill sites were 58±6mgkg(-1) for REEs comprising 44±8mgkg(-1) for light REEs, 11±2mgkg(-1) for heavy REEs and 3±1mgkg(-1) for Scandium (Sc) and 3±1.0mgkg(-1) of PGMs. Compared to the typical concentration in ores, these concentrations are too low to achieve a commercially viable extraction. However, content of other highly valuable metals (Al and Cu) was found in concentrations equating to a combined value across the four landfills of around $400 million, which increases the economic viability of landfill mining. Presence of critical metals will mainly depend on the type of waste that was buried but the recovery of these metals through landfill mining is possible and is economically feasible only if additional materials (plastics, paper, metallic items and other) are also recovered for reprocessing. PMID:25957938</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.103..161H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.103..161H"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> systematics of fossil bone revealed by LA-ICPMS analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herwartz, Daniel; Tütken, Thomas; Jochum, Klaus Peter; Sander, P. Martin</p> <p>2013-02-01</p> <p>Intra-bone rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) fractionation trends were studied by LA-ICPMS analysis to put constraints on (1) the mechanisms controlling REE fractionation within fossil bones; (2) the relative timing of REE uptake in various parts of fossil bone and (3) the origin of REE in fossil bones. We have evaluated REE bone profiles across 54 fossil bones from a broad range of well-characterised taphonomic settings ranging in age from Triassic to early Medieval. REE patterns and concentration gradients are highly variable and intra-bone fractionation trends in (La/Yb)N vs. (La/Sm)N space of few specimens cover almost the entire range previously observed for bulk samples. Intra-bone variability of Ce anomalies, as well as variable Y/Ho and (La/La?)N is also observed. Sometimes, diagenetic fluids with fractionated, HREE enriched compositions have entered the bone from the marrow cavity, producing secondary REE uptake profiles. Theoretical intra-bone fractionation trends, modelled using lattice strain theory, concur with most REE data but some trends cannot be modelled using realistic boundary conditions. This fact, as well as the occurence of positive and negative Ce anomalies within the same fossil sample, hint towards changing REE compositions of diagenetic fluids over the timescales of REE uptake. Because apparent Ce anomalies frequently evolve over bone profiles and Ce anomalies can be inherited from previous fractionation events, Ce anomalies are a highly ambiguous tracer for constraining ambient redox conditions. In general, bioapatite REE signatures may not always reliably reflect ambient taphonomic or redox conditions and diagenetic fluid compositions. Therefore REE patterns and Ce anomalies of fossil bones must be interpreted cautiously as they vary spatially within skeletal remains and are affected by intra-bone fractionation processes as well as changing compositions of the diagenetic fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018287','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018287"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> concentrations in geological and synthetic samples using synchrotron X-ray fluorescence analysis</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>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.</p> <p>1993-01-01</p> <p>The concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.154..186A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.154..186A"><span id="translatedtitle">The sedimentary flux of dissolved rare <span class="hlt">earth</span> <span class="hlt">elements</span> to the ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abbott, April N.; Haley, Brian A.; McManus, James; Reimers, Clare E.</p> <p>2015-04-01</p> <p>We determined pore fluid rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations in near-surface sediments retrieved from the continental margin off Oregon and California (USA). These sites represent shelf-to-slope settings, which lie above, within, and below the oxygen minimum zone of the Northeast Pacific. The sediments are characterized by varying degrees of net iron reduction, with pore fluids from the shelf sites being generally ferruginous, and the slope sediments having less-pronounced iron reduction zones that originate deeper in the sediment package. REE concentrations show maxima in shallow (upper 2-10 cm) subsurface pore fluids across all sites with concentrations that rise more than two orders of magnitude higher than seawater. These pore fluid enrichments highlight the importance of a sedimentary source of REEs to the ocean's water column. Here we use our measurements to estimate the diffusive flux of Nd out of ocean sediments resulting in a global flux between 18 and 110 × 106 mol Nd yr-1. While we do assume that our pore fluid profiles as well as the very limited data previously published are representative of a wide array of ocean environments, this calculated flux can account for the modeled missing Nd source flux (76 × 106 mol Nd yr-1) in global budgets (Arsouze et al., 2009). Pore fluid normalized REE patterns show distinct variation in the middle REE and heavy REE enrichments with sediment depth and amongst sites. These patterns show that the heavy REE enrichment of pore fluids at our deep slope site (3000 m water depth) is closest to the heavy REE enrichment of seawater. This observation supports the view that REE cycling within the upper ten centimeters of deep-sea marine sediments, as opposed to shallower continental shelf and slope sediments, plays a significant role in controlling the integrated global REE flux from the pore fluids and consequently the broad-scale REE pattern in seawater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GGG....16.2679Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GGG....16.2679Z"><span id="translatedtitle">Factors affecting the rare <span class="hlt">earth</span> <span class="hlt">element</span> compositions in massive sulfides from deep-sea hydrothermal systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zeng, Zhigang; Ma, Yao; Yin, Xuebo; Selby, David; Kong, Fancui; Chen, Shuai</p> <p>2015-09-01</p> <p>To reconstruct the evolution of ore-forming fluids and determine the physicochemical conditions of deposition associated with seafloor massive sulfides, we must better understand the sources of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), the factors that affect the REE abundance in the sulfides, and the REE flux from hydrothermal fluids to the sulfides. Here we examine the REE profiles of 46 massive sulfide samples collected from seven seafloor hydrothermal systems. These profiles feature variable total REE concentrations (37.2-4092 ppb) and REE distribution patterns (LaCN/LuCN ratios = 2.00-73.8; (Eu/Eu*)CN ratios = 0.34-7.60). The majority of the REE distribution patterns in the sulfides are similar to those of vent fluids, with the sulfides also exhibiting light REE enrichment. We demonstrate that the variable REE concentrations, Eu anomalies, and fractionation between light REEs and heavy REEs in the sulfides exhibit a relationship with the REE properties of the sulfide-forming fluids and the massive sulfide chemistry. Based on the sulfide REE data, we estimate that modern seafloor sulfide deposits contain approximately 280 t of REEs. According to the flux of hydrothermal fluids at mid-ocean ridges (MORs) and an average REE concentration of 3 ng/g in these fluids, hydrothermal vents at MORs alone transport more REEs (>360 t) to the oceans over the course of just 2 years than the total quantity of REEs in seafloor sulfides. The excess REEs (i.e., the quantity not captured by massive sulfides) may be transported away from the systems and become bound in sulfate deposits and metalliferous sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://solarsystem.wustl.edu/wp-content/uploads/reprints/2009/SF08trace-revision2.pdf','EPRINT'); return false;" href="http://solarsystem.wustl.edu/wp-content/uploads/reprints/2009/SF08trace-revision2.pdf"><span id="translatedtitle">C:\\Laura\\Ivtan\\Early <span class="hlt">Earth</span>\\trace <span class="hlt">elements</span>\\drafts\\SF08trace-revision2.doc 4:04:50 PM 7/23/2009 Volatile <span class="hlt">Element</span> Chemistry during Metamorphism of Ordinary Chondritic Material</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p></p> <p></p> <p>C:\\Laura\\Ivtan\\Early <span class="hlt">Earth</span>\\trace <span class="hlt">elements</span>\\drafts\\SF08trace-revision2.doc 4:04:50 PM 7/23/2009 1 Volatile <span class="hlt">Element</span> Chemistry during Metamorphism of Ordinary Chondritic Material and Some of its Implications: 5 #12;C:\\Laura\\Ivtan\\Early <span class="hlt">Earth</span>\\trace <span class="hlt">elements</span>\\drafts\\SF08trace-revision2.doc 4:04:50 PM 7</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940030959','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940030959"><span id="translatedtitle">Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace <span class="hlt">element</span> <span class="hlt">geochemistry</span>, isotopic abundances, and trace organic chemistry of several fragments from L2008#5</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.</p> <p>1994-01-01</p> <p>The topics discussed include the following: noble gas content and release temperatures; trace <span class="hlt">element</span> abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5437290','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5437290"><span id="translatedtitle">Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in fluid inclusions by inductively coupled plasma-mass spectrometry (ICP-MS)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ghazi, A.M.; Vanko, D.A. ); Roedder, E. ); Seeley, R.C. )</p> <p>1993-09-01</p> <p>An inductively coupled plasma-mass spectrometer (ICP-MS) is used to determine rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) abundances in fluid inclusions. Quartz concentrates from the Bingham porphyry Cu-Mo deposit, Utah, US, and from a quartz vein in brecciated amphibolite dredged from the Mathematician Ridge, an abandoned spreading center in the eastern Pacific, were prepared by a modified crush-leach method. Leachates and solutions from acid digestion of quartz residue from leaching were analyzed by ICP-MS, using conventional sample introduction. The results demonstrate that the crush-leach method, followed by ICP-MS analysis of leachates, is effective for REE determination. Chondrite-normalized REE patterns for the Bingham samples are light rare <span class="hlt">earth</span> <span class="hlt">elements</span> (LREE) enriched, with a small negative Eu anomaly, and the pattern for the Mathematician Ridge sample is nearly flat, with a positive Eu anomaly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070005032','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070005032"><span id="translatedtitle">Not So Rare <span class="hlt">Earth</span>? New Developments in Understanding the Origin of the <span class="hlt">Earth</span> and Moon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, Kevin</p> <p>2007-01-01</p> <p>A widely accepted model for the origin of the <span class="hlt">Earth</span> and Moon has been a somewhat specific giant impact scenario involving an impactor to proto-<span class="hlt">Earth</span> mass ratio of 3:7, occurring 50-60 Ma after T(sub 0), when the <span class="hlt">Earth</span> was only half accreted, with the majority of <span class="hlt">Earth</span>'s water then accreted after the main stage of growth, perhaps from comets. There have been many changes to this specific scenario, due to advances in isotopic and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span>, more detailed, improved, and realistic giant impact and terrestrial planet accretion modeling, and consideration of terrestrial water sources other than high D/H comets. The current scenario is that the <span class="hlt">Earth</span> accreted faster and differentiated quickly, the Moon-forming impact could have been mid to late in the accretion process, and water may have been present during accretion. These new developments have broadened the range of conditions required to make an <span class="hlt">Earth</span>-Moon system, and suggests there may be many new fruitful avenues of research. There are also some classic and unresolved problems such as the significance of the identical O isotopic composition of the <span class="hlt">Earth</span> and Moon, the depletion of volatiles on the lunar mantle relative to <span class="hlt">Earth</span>'s, the relative contribution of the impactor and proto-<span class="hlt">Earth</span> to the Moon's mass, and the timing of <span class="hlt">Earth</span>'s possible atmospheric loss relative to the giant impact.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20995431','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20995431"><span id="translatedtitle">Experimental Investigation of Evaporation Behavior of Polonium and Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> in Lead-Bismuth Eutectic Pool</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shuji Ohno; Shinya Miyahara; Yuji Kurata; Ryoei Katsura; Shigeru Yoshida</p> <p>2006-07-01</p> <p>Equilibrium evaporation behavior was experimentally investigated for polonium ({sup 210}Po) in liquid lead-bismuth eutectic (LBE) and for rare-<span class="hlt">earth</span> <span class="hlt">elements</span> gadolinium (Gd) and europium (Eu) in LBE to understand and clarify the transfer behavior of toxic impurities from LBE coolant to a gas phase. The experiments utilized the 'transpiration method' in which saturated vapor in an isothermal evaporation pot was transported by inert carrier gas and collected outside of the pot. While the previous paper ICONE12-49111 has already reported the evaporation behavior of LBE and of tellurium in LBE, this paper summarizes the outlines and the results of experiments for important impurity materials {sup 210}Po and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> which are accumulated in liquid LBE as activation products and spallation products. In the experiments for rare-<span class="hlt">earth</span> <span class="hlt">elements</span>, non-radioactive isotope was used. The LBE pool is about 330-670 g in weight and has a surface area of 4 cm x 14 cm. {sup 210}Po experiments were carried out with a smaller test apparatus and radioactive {sup 210}Po produced through neutron irradiation of LBE in the Japan Materials Testing Reactor (JMTR). We obtained fundamental and instructive evaporation data such as vapor concentration, partial vapor pressure of {sup 210}Po in the gas phase, and gas-liquid equilibrium partition coefficients of the impurities in LBE under the temperature condition between 450 and 750 deg. C. The {sup 210}Po test revealed that Po had characteristics to be retained in LBE but was still more volatile than LBE solvent. A part of Eu tests implied high volatility of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> comparable to that of Po. This tendency is possibly related to the local enrichment of the solute near the pool surface and needs to be investigated more. These results are useful and indispensable for the evaluation of radioactive materials transfer to the gas phase in LBE-cooled nuclear systems. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Litho.172..192C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Litho.172..192C"><span id="translatedtitle">Mineral chemistry of Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> (REE) mineralization, Browns Ranges, Western Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cook, Nigel J.; Ciobanu, Cristiana L.; O'Rielly, Daniel; Wilson, Robin; Das, Kevin; Wade, Benjamin</p> <p>2013-07-01</p> <p>‘Green energy futures’ are driving unprecedented demand for Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE), underpinning significant exploration activity worldwide. Understanding how economic REE concentrations form is critical for development of exploration models. REE mineralisation in the Browns Ranges, Gordon Downs Region, Western Australia, comprises xenotime-dominant mineralisation hosted within Archaean to Palaeoproterozoic metasedimentary units (Browns Range Metamorphics). Mineralogical, petrographic and mineral-chemical investigation, including trace <span class="hlt">element</span> analysis by Laser-Ablation Inductively-Coupled Plasma Mass Spectroscopy, gives insights into the mineralogical distribution and partitioning of REE, and also provides evidence for the genetic evolution of the Browns Range REE mineralisation via a succession of hydrothermal processes. Two main REE-bearing minerals are identified: xenotime [(Y,REE)PO4], which is HREE selective; and subordinate florencite [(REEAl3(PO4)2(OH)6] which is LREE selective. Two morphological generations of xenotime are recognised; compositions are however consistent. Xenotime contains Dy (up to 6.5 wt.%), Er (up to 4.35 wt.%), Gd (up to 7.56 wt.%), Yb (up to 4.65 wt.%) and Y (up to 43.3 wt.%). Laser Ablation ICP-MS <span class="hlt">element</span> mapping revealed a subtle compositional zoning in some xenotime grains. LREE appear concentrated in the grain cores or closest to the initial point of growth whereas HREE, particularly Tm, Yb and Lu, are highest at the outer margins of the grains. The HREE enrichment at the outer margins is mimicked by As, Sc, V, Sr, U, Th and radiogenic Pb. Florencite is commonly zoned and contains Ce (up to 11.54 wt.%), Nd (up to 10.05 wt.%) and La (up to 5.40 wt.%) and is also notably enriched in Sr (up to 11.63 wt.%) and Ca. Zircon (which is not a significant contributor of REEs overall due to its low abundance in the rocks) is also enriched in REE (up to 13 wt.% ?REE) and is the principal host of Sc (up to 0.8 wt.%). Early, coarse euhedral xenotime has undergone fracturing, partial breakdown and replacement by florencite. Second generation xenotime occurs as abundant small blades commonly associated with acicular hematite. Mineralization is attributed to percolation of a volatile-rich, acidic fluid, possibly granite-derived, through porous arkose units. Late hematite may suggest mixing with meteoric water and subsequent oxidation. Field observations suggest that faults acted as fluid conduits and that brecciation, possibly associated with release of volatiles from the fluid, occurred along these faults. The data provide valuable constraints on chemical compositional trends in xenotime and coexisting minerals. Given the current surge in exploration for REE, this information will assist in the development of exploration models for comparable terranes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17622499','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17622499"><span id="translatedtitle"><span class="hlt">Geochemistry</span> in the modern soil survey program.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wilson, M A; Burt, R; Indorante, S J; Jenkins, A B; Chiaretti, J V; Ulmer, M G; Scheyer, J M</p> <p>2008-04-01</p> <p><span class="hlt">Elemental</span> analysis has played an important role in the characterization of soils since inception of the soil survey in the US. Recent efforts in analysis of trace and major <span class="hlt">elements</span> (<span class="hlt">geochemistry</span>) have provided necessary data to soil survey users in a variety of areas. The first part of this paper provides a brief overview of <span class="hlt">elemental</span> sources, forms, mobility, and bioavailability; critical aspects important to users of soil survey geochemical data for appropriate use and interpretations. Examples are provided based on data gathered as part of the US soil survey program. The second part addresses the organization of sample collection in soil survey and how soil surveys are ideally suited as a sampling strategy for soil geochemical studies. <span class="hlt">Geochemistry</span> is functional in characterization of soil types, determining soil processes, ecological evaluation, or issues related to soil quality and health, such as evaluating suitability of soils for urban or agricultural land use. Applications of <span class="hlt">geochemistry</span> are on-going across the US and are documented herein. This analytical direction of soil survey complements historic efforts of the National Cooperative Soil Survey Program and addresses the increasing need of soil survey users for data that assists in understanding the influence of human activities on soil properties. PMID:17622499</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19760087381&hterms=Chelsea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DChelsea','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19760087381&hterms=Chelsea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DChelsea"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> abundances in rocks and minerals from the Fiskenaesset Complex, West Greenland. [comparison with lunar anorthosites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Henderson, P.; Fishlock, S. J.; Laul, J. C.; Cooper, T. D.; Conard, R. L.; Boynton, W. V.; Schmitt, R. A.</p> <p>1976-01-01</p> <p>The paper reports activation-analysis determinations of rare-<span class="hlt">earth-element</span> (REE) and other trace-<span class="hlt">element</span> concentrations in selected rocks, plagioclase, and mafic separates from the Fiskenaesset Complex. The REE abundances are found to be very low and atypical in comparison with other terrestrial anorthosites. The plagioclases are shown to be characterized by a deficiency in heavy RE <span class="hlt">elements</span> relative to light ones and a positive Eu anomaly, while the mafic separates are enriched in heavy rare <span class="hlt">earths</span> and have no Eu anomaly, except in one sample. It is found that the bulk and trace-<span class="hlt">element</span> abundances of the plagioclases are similar to those observed in some lunar anorthosites, but the degree of Eu anomaly is less in the plagioclases. The data are taken as confirmation of the idea that fractionation processes were involved in the origin of the Complex, and it is concluded that the Complex may have been produced from a magma generated by partial melting of a garnet-bearing source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1611789M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1611789M"><span id="translatedtitle">Natural and anthropogenic rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Lago de Paranoá, Brasilia, Brazil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merschel, Gila; Baldewein, Linda; Bau, Michael; Dantas, Elton Luiz; Walde, Detlef; Bühn, Bernhard</p> <p>2014-05-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) belong to the group of particle reactive <span class="hlt">elements</span> and occur at ultratrace levels in natural waters. They are exclusively trivalent, but Ce and Eu can also be tetravalent and divalent, respectively, depending on the redox-level, the pH and the temperature of the fluid. Due to these redox changes, normalized REE patterns may show Ce and/or Eu anomalies. Recently, these high-tech metals raised significant public attention, as they are of great economic importance and consumption and hence release into the environment increased sharply. The most prominent example of a REE contamination is anthropogenic Gd, which is derived from Gd-based contrast agents used in magnetic resonance imaging. Due to their high stabilities, these compounds are not readily removed by commonly applied waste water treatment technologies and, therefore, are released from treatment plants into surface and ground waters. Hence, this anthropogenic Gd can be used as a tracer for the presence of waste water-derived substances such as pharmaceuticals and personal care products in river, lake, ground and tap waters. Lago de Paranoá is an artificial reservoir lake in the city of Brasilia, Brazil, and is currently considered a potential freshwater resource. The city's two waste water treatment plants are located on its shore and their effluents are discharged into the lake. To investigate the level of contamination, we took water samples at 11 stations in the lake and compared the REE concentrations in unfiltered and filtered (<200 nm) lake water. The unfiltered water samples show light REE enrichment (LaSN/YbSN: 1.37-1.98) and high REE concentrations (Sum REE: 192 - 476 ng/L), while the unfiltered water samples are heavy REE enriched (LaSN/YbSN: 0.15-0.61) at lower concentrations (Sum REE: 50 - 85 ng/L). This is due to the fact that light REE are preferentially bound to particle surfaces, while the heavy REE are preferentially complexed with ligands in solution. In marked contrast to the filtered samples, REE patterns of the unfiltered waters show a positive anomaly of redox-sensitive Ce. This reveals oxidative scavenging of Ce onto particles in the lake water. As lithic particles, such as atmospheric dust, do not show positive Ce anomalies, the particles responsible for Ce oxidation are either inorganic Mn or Fe (oxyhydr-) oxides or organic particulates, which are known to oxidatively scavenge Ce. All samples show pronounced positive Gd anomalies, revealing the presence of waste water-derived anthropogenic Gd in the lake waters. Because the anthropogenic Gd is bound to a very stable water-soluble chemical complex, it does not react with particles. Hence, both the filtered and unfiltered samples show REE patterns with a similar-sized positive Gd anomaly. The presence of anthropogenic Gd indicates that other waste water-derived substances of potentially high (eco-) toxicity may also be present in the lake water. This needs to be further investigated and monitored before using the lake water as a drinking water resource.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995AcSpe..50.1365G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995AcSpe..50.1365G"><span id="translatedtitle">Mechanism of vaporization of yttrium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in electrothermal vaporization inductively coupled plasma mass spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goltz, D. M.; Grégoire, D. C.; Chakrabarti, C. L.</p> <p>1995-09-01</p> <p>The mechanism of vaporization of yttrium and the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) has been studied using graphite furnace atomic absorption spectrometry (GFAAS) and inductively-coupled plasma mass spectrometry (ICP-MS). The appearance temperatures for Y and the REEs obtained by GFAAS were generally identical to the appearance temperatures obtained using ETV-ICP-MS. At lower temperatures, Y and the REEs are predominantly vaporized in atomic form or as oxides, while at temperatures above 2500°C, the <span class="hlt">elements</span> are vaporized as oxides and/or carbides. This accounts for the very high sensitivity of ETV-ICP-MS compared to GFAAS for the determination of these <span class="hlt">elements</span>. Absolute limits of detection for Y and all of the REEs using ETV-ICP-MS ranged from 0.002 pg for Tm to 0.2 pg for Ce. The use of freon as a chemical modifier was effective in controlling analyte carbide formation and reducing memory effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070009997','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070009997"><span id="translatedtitle">Highly Sideophile <span class="hlt">Element</span> Abundance Constraints on the Nature of the Late Accretionary Histories of <span class="hlt">Earth</span>, Moon and Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Walker, R. J.; Puchtel, I. S.; Brandon, A. D.; Horan, M. F.; James, O. B.</p> <p>2007-01-01</p> <p>The highly siderophile <span class="hlt">elements</span> (HSE) include Re, Os, Ir, Ru, Pt and Pd. These <span class="hlt">elements</span> are initially nearly-quantitatively stripped from planetary silicate mantles during core segregation. They then may be re-enriched in mantles via continued accretion sans continued core segregation. This suite of <span class="hlt">elements</span> and its included long-lived radiogenic isotopes systems (Re-187 (right arrow) Os-187; Pt-190 (right arrow) Os-186) can potentially be used to fingerprint the characteristics of late accreted materials. The fingerprints may ultimately be useful to constrain the prior nebular history of the dominant late accreted materials, and to compare the proportion and genesis of late accretionary materials added to the inner planets. The past ten years have seen considerable accumulation of isotopic and compositional data for HSE present in the <span class="hlt">Earth</span>'s mantle, lunar mantle and impact melt breccias, and Martian meteorites. Here we review some of these data and consider the broader implications of the compiled data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26014901','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26014901"><span id="translatedtitle">An Operationally Simple Method for Separating the Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> Neodymium and Dysprosium.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J</p> <p>2015-07-01</p> <p>Rare-<span class="hlt">earth</span> metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare <span class="hlt">earths</span>. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-<span class="hlt">earth</span> metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three ?(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-<span class="hlt">earth</span> metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359. PMID:26014901</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CRGeo.347..213C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CRGeo.347..213C"><span id="translatedtitle">Geochemical and isotopic record of anthropogenic activities - Thematic issue dedicated to Jean Carignan (1965-2012). Part 1: Radiogenic isotopes and <span class="hlt">elemental</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chabaux, François; Sonke, Jeroen E.; Négrel, Philippe; Cloquet, Christophe</p> <p>2015-09-01</p> <p>Anthropogenic activities are today one of the major factors controlling the evolution of our environment with major consequences on all <span class="hlt">Earth</span> surface compartments: atmosphere, oceans, continents and biosphere. Such consequences accelerated with the industrial revolution, but probably started much earlier as they are related to the demographic evolution and the settlement of various human communities during the last millennia. They are presently reaching unequal effects all over the globe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRD..118.6017A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRD..118.6017A"><span id="translatedtitle">Robust <span class="hlt">elements</span> of Snowball <span class="hlt">Earth</span> atmospheric circulation and oases for life</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abbot, Dorian S.; Voigt, Aiko; Li, Dawei; Le Hir, Guillaume; Pierrehumbert, Raymond T.; Branson, Mark; Pollard, David; Koll, Daniel D. B.</p> <p>2013-06-01</p> <p>Atmospheric circulation in a Snowball <span class="hlt">Earth</span> is critical for determining cloud behavior, heat export from the tropics, regions of bare ice, and sea glacier flow. These processes strongly affect Snowball <span class="hlt">Earth</span> deglaciation and the ability of oases to support photosynthetic marine life throughout a Snowball <span class="hlt">Earth</span>. Here we establish robust aspects of the Snowball <span class="hlt">Earth</span> atmospheric circulation by running six general circulation models with consistent Snowball <span class="hlt">Earth</span> boundary conditions. The models produce qualitatively similar patterns of atmospheric circulation and precipitation minus evaporation. The strength of the Snowball Hadley circulation is roughly double modern at low CO2 and greatly increases as CO2 is increased. We force a 1?D axisymmetric sea glacier model with general circulation model (GCM) output and show that, neglecting zonal asymmetry, sea glaciers would limit ice thickness variations to O(10%). Global mean ice thickness in the 1?D sea glacier model is well?approximated by a 0?D ice thickness model with global mean surface temperature as the upper boundary condition. We then show that a thin?ice Snowball solution is possible in the axysymmetric sea glacier model when forced by output from all the GCMs if we use ice optical properties that favor the thin?ice solution. Finally, we examine Snowball oases for life using analytical models forced by the GCM output and find that conditions become more favorable for oases as the Snowball warms, so that the most critical time for the survival of life would be near the beginning of a Snowball <span class="hlt">Earth</span> episode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018828','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018828"><span id="translatedtitle">A summary of the effects of mining and related activities on the sediment-trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of Lake Coeur d'Alene, Idaho, USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Horowitz, A.J.; Elrick, K.A.; Robbins, J.A.; Cook, R.B.</p> <p>1995-01-01</p> <p>Substantial portions of the surface and near-surface sediments are markedly enriched in Ag, As, Cd, Hg, Pb, Sb and Zn, and somewhat enriched in Cu, Fe and Mn. Surface distribution patterns, as well as variations in the thickness of the trace <span class="hlt">element</span>-rich subsurface sediments, indicate that the source of much of this enriched material is the Coeur d'Alene River. An estimated 75 million metric tons of trace <span class="hlt">element</span>-rich sediments have been deposited on or in the lakebed. The deposition of trace <span class="hlt">element</span>-rich sediments began, at least in the Coeur d'Alene River delta, some time between 1895 and 1910, dates consistent with the onset of mining and ore-processing activities that began in the area in the 1880's. -from Authors</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70019953','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70019953"><span id="translatedtitle">Incorporation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in titanite: Stabilization of the A2/a dimorph by creation of antiphase boundaries</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hughes, J.M.; Bloodaxe, E.S.; Hanchar, J.M.; Foord, E.E.</p> <p>1997-01-01</p> <p>The atomic arrangement of a natural rare-<span class="hlt">earth</span>-rich titanite and two synthetic rare-<span class="hlt">earth</span>-doped titanites have been refined in space group A2/a, and the atomic arrangement of an undoped P21/a synthetic titanite was also refined for comparison. Previous work has shown that titanite possesses a domain structure, with domains formed of like-displaced Ti atoms in the [100] octahedral chains. P21/a titanite results when the crystal is formed of a single domain, but as Ti-reversal sites occur in the octahedral chain the apparent A2/a structure results from the average of antiphase domains. Antiphase boundaries occur at O1, which is alternately overbonded or underbonded at the boundaries, depending on the displacement of the neighboring Ti atoms. Type 2 antiphase boundaries exist where two Ti atoms are displaced away from the intervening O1 atom and are energetically unfavorable because of underbonding of that O1 atom. However, substitution of a trivalent rare <span class="hlt">earth</span> <span class="hlt">element</span> in the adjacent Ca2+ site relieves that underbonding, favoring the creation of type 2 antiphase boundaries and stabilization of the A2/a dimorph. The results of high-precision crystal structure analyses demonstrate that rare <span class="hlt">earth</span> substituents for Ca stabilize the A2/a dimorph at lower substitution levels than required for octahedral substitutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25929077','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25929077"><span id="translatedtitle">[Rare <span class="hlt">earth</span> <span class="hlt">elements</span> content in farmland soils and crops of the surrounding copper mining and smelting plant in Jiangxi province and evaluation of its ecological risk].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jin, Shu-Lan; Huang, Yi-Zong; Wang, Fei; Xu, Feng; Wang, Xiao-Ling; Gao, Zhu; Hu, Ying; Qiao Min; Li, Jin; Xiang, Meng</p> <p>2015-03-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> content in farmland soils and crops of the surrounding copper mining and smelting plant in Jiangxi province was studied. The results showed that copper mining and smelting could increase the content of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soils and crops. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> content in farmland soils of the surrounding Yinshan Lead Zinc Copper Mine and Guixi Smelting Plant varied from 112.42 to 397.02 mg x kg(-1) and 48.81 to 250.06 mg x kg(-1), and the average content was 254.84 mg x kg(-1) and 144.21 mg x kg(-1), respectively. The average contents of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in soils in these two areas were 1.21 times and 0.68 times of the background value in Jiangxi province, 1.36 times and 0.77 times of the domestic background value, 3.59 times and 2.03 times of the control samples, respectively. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> content in 10 crops of the surrounding Guixi Smelting Plant varied from 0.35 to 2.87 mg x kg(-1). The contents of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the leaves of crops were higher than those in stem and root. The contents of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Tomato, lettuce leaves and radish leaves were respectively 2.87 mg x kg(-1), 1.58 mg x kg(-1) and 0.80 mg x kg(-1), which were well above the hygienic standard limit of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in vegetables and fruits (0.70 mg x kg(-1)). According to the health risk assessment method recommended by America Environmental Protection Bureau (USEPA), we found that the residents' lifelong average daily intake of rare <span class="hlt">earth</span> <span class="hlt">elements</span> was 17.72 mg x (kg x d)(-1), lower than the critical value of rare <span class="hlt">earth</span> <span class="hlt">elements</span> damage to human health. The results suggested that people must pay attention to the impact of rare <span class="hlt">earth</span> <span class="hlt">elements</span> on the surrounding environment when they mine and smelt copper ore in Jiangxi. PMID:25929077</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=257107&keyword=turbine&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=48161742&CFTOKEN=16623721','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=257107&keyword=turbine&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=48161742&CFTOKEN=16623721"><span id="translatedtitle">COST-EFFECTIVE RARE <span class="hlt">EARTH</span> <span class="hlt">ELEMENT</span> RECYCLING PROCESS FROM INDUSTRIAL SCRAP AND DISCARDED ELECTRONIC PRODUCTS TO VALUABLE MAGNETIC ALLOYS AND PERMANENT MAGNETS - PHASE II</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><p> Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) based Nd-Fe-B and Sm-Co permanent magnets have been widely used because of their excellent magnetic properties. The applications of Nd-Fe-B and Sm-Co rare <span class="hlt">earth</span> permanent magnets include hybrid electric vehicles (HEVs), power generators for wind tur...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://geosci.uchicago.edu/~rtp1/papers/jgrd50540.pdf','EPRINT'); return false;" href="http://geosci.uchicago.edu/~rtp1/papers/jgrd50540.pdf"><span id="translatedtitle">JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES, VOL. 118, 60176027, doi:10.1002/jgrd.50540, 2013 Robust <span class="hlt">elements</span> of Snowball <span class="hlt">Earth</span> atmospheric circulation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p></p> <p></p> <p>Robust <span class="hlt">elements</span> of Snowball <span class="hlt">Earth</span> atmospheric circulation and oases for life Dorian S. Abbot,1 Aiko Voigt Snowball <span class="hlt">Earth</span> deglaciation and the ability of oases to support photosynthetic marine life throughout use ice optical properties that favor the thin-ice solution. Finally, we examine Snowball oases</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JVGR..263..108T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JVGR..263..108T"><span id="translatedtitle">The magma plumbing system of Bezymianny Volcano: Insights from a 54 year time series of trace <span class="hlt">element</span> whole-rock <span class="hlt">geochemistry</span> and amphibole compositions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turner, Stephen J.; Izbekov, Pavel; Langmuir, Charles</p> <p>2013-08-01</p> <p>Samples from 33 individual eruptions of Bezymianny volcano between 1956 and 2010 provide an opportunity to study in detail the temporal evolution of an arc volcano. Major <span class="hlt">element</span> and ICP-MS trace <span class="hlt">element</span> analyses show that the eruptive products shifted progressively from relatively silicic magma in 1956 (~ 60.4% SiO2) to more mafic compositions (e.g. 56.8% SiO2 in 2010). Amphibole compositions changed concurrently from low-Al2O3 to high-Al2O3. Whole rock <span class="hlt">element-element</span> variation diagrams show tight compositional arrays, some with a distinct kink in the late 1970s, which cannot be reproduced by fractionation of a single magma along a liquid line of descent. Amphibole thermobarometry indicates amphibole crystallization in two separate reservoirs, one between 200 and 300 MPa, and another between 500 and 750 MPa. Liquid compositions calculated from the amphibole analyses show that liquids stored in each reservoir become increasingly mafic from 1956 to 2010, suggesting that each reservoir received magma inputs from more mafic sources throughout the eruptive cycle. End member mixing analysis of the dataset allows calculation of three end member compositions that can be combined in varying proportions to reproduce major and trace <span class="hlt">element</span> whole rock compositions. The end-member mixing proportions vary systematically between 1956 and 2010, with maxima for end-members A, B and C during 1956, 1977, and 2010, respectively. Major <span class="hlt">element</span> compositions of phenocrysts, combined with published trace <span class="hlt">element</span> partition coefficients, show that each end member may have evolved from a common parental magma by fractionation of three different mineral assemblages, possibly due to different pressures of crystallization and volatile contents. The petrologic data are consistent with three magma reservoirs at different depths. Magmas from the shallowest reservoir erupted first, with increasing proportions of deeper reservoirs over time. Past studies have demonstrated similarities in eruptive style between Bezymianny and both Mount St. Helens and Soufrière Hills volcanoes. Contrasting time series data show that the magma plumbing systems of Mount St. Helens and Bezymianny have little in common, while Soufrière Hills may be a better analog. Similar eruptive styles at the surface do not necessarily reflect similar systems of magma supply and evolution at depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15701392','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15701392"><span id="translatedtitle">Distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in an alluvial aquifer affected by acid mine drainage: the Guadiamar aquifer (SW Spain).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Olías, M; Cerón, J C; Fernández, I; De la Rosa, J</p> <p>2005-05-01</p> <p>This work analyses the spatial distribution, the origin, and the shale-normalised fractionation patterns of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in the alluvial aquifer of the Guadiamar River (south-western Spain). This river received notoriety in April 1998 for a spill that spread a great amount of slurry (mainly pyrites) and acid waters in a narrow strip along the river course. Groundwaters and surface waters were sampled to analyse, among other <span class="hlt">elements</span>, the REEs. Their spatial distribution shows a peak close to the mining region, in an area with low values of pH and high concentrations of sulphates and other metals such as Zn, Cu, Co, Ni, Pb, and Cd. The patterns of shale-normalised fractionation at the most-contaminated points show an enrichment in the middle rare <span class="hlt">earth</span> <span class="hlt">elements</span> (MREE) with respect to the light (LREE) and heavy (HREE) ones, typical of acid waters. The Ce-anomaly becomes more negative as pH increases, due to the preferential fractionation of Ce in oxyhydroxides of Fe. PMID:15701392</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/doepatents/biblio/873910','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/doepatents/biblio/873910"><span id="translatedtitle">Extraction processes and solvents for recovery of cesium, strontium, rare <span class="hlt">earth</span> <span class="hlt">elements</span>, technetium and actinides from liquid radioactive waste</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Zaitsev, Boris N. (St. Petersburg, RU); Esimantovskiy, Vyacheslav M. (St. Petersburg, RU); Lazarev, Leonard N. (St. Petersburg, RU); Dzekun, Evgeniy G. (Ozersk, RU); Romanovskiy, Valeriy N. (St. Petersburg, RU); Todd, Terry A. (Aberdeen, ID); Brewer, Ken N. (Arco, ID); Herbst, Ronald S. (Idaho Falls, ID); Law, Jack D. (Pocatello, ID)</p> <p>2001-01-01</p> <p>Cesium and strontium are extracted from aqueous acidic radioactive waste containing rare <span class="hlt">earth</span> <span class="hlt">elements</span>, technetium and actinides, by contacting the waste with a composition of a complex organoboron compound and polyethylene glycol in an organofluorine diluent mixture. In a preferred embodiment the complex organoboron compound is chlorinated cobalt dicarbollide, the polyethylene glycol has the formula RC.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.n OH, and the organofluorine diluent is a mixture of bis-tetrafluoropropyl ether of diethylene glycol with at least one of bis-tetrafluoropropyl ether of ethylene glycol and bis-tetrafluoropropyl formal. The rare <span class="hlt">earths</span>, technetium and the actinides (especially uranium, plutonium and americium), are extracted from the aqueous phase using a phosphine oxide in a hydrocarbon diluent, and reextracted from the resulting organic phase into an aqueous phase by using a suitable strip reagent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/925482','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/925482"><span id="translatedtitle">Appendix G: <span class="hlt">Geochemistry</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cantrell, Kirk J.; Serne, R. Jeffrey; Zachara, John M.; Krupka, Kenneth M.; Dresel, P. Evan; Brown, Christopher F.; Freshley, Mark D.</p> <p>2008-01-17</p> <p>This appendix discusses the geology of the Hanford Site and singe-shell tank (SST) waste management areas (WMAs). The purpose is to provide the most recent geochemical information available for the SST WMAs and the Integrated Disposal Facility. This appendix summarizes the information in the <span class="hlt">geochemistry</span> data package for the SST WMAs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024831','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024831"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> variations resulting from inversion of pigeonite and subsolidus reequilibration in lunar ferroan anorthosites</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>James, O.B.; Floss, C.; McGee, J.J.</p> <p>2002-01-01</p> <p>We present results of a secondary ion mass spectrometry study of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22622575','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22622575"><span id="translatedtitle">Statistical <span class="hlt">geochemistry</span> reveals disruption in secular lithospheric evolution about 2.5?Gyr ago.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Keller, C Brenhin; Schoene, Blair</p> <p>2012-05-24</p> <p>The <span class="hlt">Earth</span> has cooled over the past 4.5 billion years (Gyr) as a result of surface heat loss and declining radiogenic heat production. Igneous <span class="hlt">geochemistry</span> has been used to understand how changing heat flux influenced Archaean geodynamics, but records of systematic geochemical evolution are complicated by heterogeneity of the rock record and uncertainties regarding selection and preservation bias. Here we apply statistical sampling techniques to a geochemical database of about 70,000 samples from the continental igneous rock record to produce a comprehensive record of secular geochemical evolution throughout <span class="hlt">Earth</span> history. Consistent with secular mantle cooling, compatible and incompatible <span class="hlt">elements</span> in basalts record gradually decreasing mantle melt fraction through time. Superimposed on this gradual evolution is a pervasive geochemical discontinuity occurring about 2.5?Gyr ago, involving substantial decreases in mantle melt fraction in basalts, and in indicators of deep crustal melting and fractionation, such as Na/K, Eu/Eu* (europium anomaly) and La/Yb ratios in felsic rocks. Along with an increase in preserved crustal thickness across the Archaean/Proterozoic boundary, these data are consistent with a model in which high-degree Archaean mantle melting produced a thick, mafic lower crust and consequent deep crustal delamination and melting--leading to abundant tonalite-trondhjemite-granodiorite magmatism and a thin preserved Archaean crust. The coincidence of the observed changes in <span class="hlt">geochemistry</span> and crustal thickness with stepwise atmospheric oxidation at the end of the Archaean eon provides a significant temporal link between deep <span class="hlt">Earth</span> geochemical processes and the rise of atmospheric oxygen on the <span class="hlt">Earth</span>. PMID:22622575</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.B31B1097D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B31B1097D"><span id="translatedtitle">Composition of olivine-rich gabbroic rocks at the Atlantis Massif (MAR 30°N,IODP site U1309D). In situ trace <span class="hlt">element</span> <span class="hlt">geochemistry</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drouin, M.; Godard, M.; Ildefonse, B.</p> <p>2006-12-01</p> <p>IODP Site U1309 was drilled at Atlantis Massif, an oceanic core complex located on the western flank of the Mid-Atlantic ridge at 30°N (IODP Expeditions 304 and 305). The 1415 m deep hole U1309D mostly recovered gabbroic rock types. Olivine-rich rocks (ol > 70%) represent 5.4% of the recovered rocks. Here, we present a multi-<span class="hlt">elemental</span> study (LA-ICPMS) of ol-rich rocks and associated gabbros coming from four ol- rich zones along Hole U1309D. Ol-rich rocks have compositions that overlap the most primitive gabbroic rocks drilled at the Mid-Atlantic Ridge (23°N and 15°N) and at the Southwest Indian Ridge (ODP Hole 735B), with Mg# ranging from 83 to 90 and Ni contents up to 2400 ppm. These compositions reflect not only olivine abundance in these samples but also the primitive compositions of olivine (Mg# 84 to 88 and Ni = 1500-2300 ppm). Cpx associated mafic phases in ol-rich rocks have primitive compositions with high Mg# (85-89.5). In interstitial Cpx, TiO2 average contents vary from 0.3% in the cores to 0.5 to 0.7% in the rims. Poikilitic Cpx are also zoned. In zone 1 (300.91mbsf to 362.9 mbsf) plagioclase have the higher An contents (79-81.6 %). They have compositions of impregnated dunite. Cumulus Cpx and Plg in gabbro show no major <span class="hlt">elements</span> variation between cores and rims. Cpx are depleted in trace <span class="hlt">element</span> (on average <10 x PM), and have light REE depleted patterns (La < 1 Yb 10 x chondrites). They are in equilibrium with MORBs in both gabbros and ol-rich rocks. Cpx composition varies as a function of sample texture. Poikilitic Cpx show variable trace <span class="hlt">element</span> contents in a single large grain (Yb normalized to chondrites: 7.5 ppm to 12.4 ppm), while cumulus Cpx show no variation. All rock types in the 4 olivine-rich zones are in the same range of trace <span class="hlt">element</span> compositions. Gabbros have the more depleted composition (YbN: 5.7 to 10.5 ppm). Pl are also depleted in trace <span class="hlt">elements</span> (<1 x PM) and REE (La < 1 - Yb 0.1 x chondrites) throughout the whole core. These results are not consistent with a simple fractional crystallization sequence. They suggest instead a complex crystallization history in an open system, in a zone of important melt transfer and magmatic accumulation, with fundamental implications on crustal accretion processes at slow-spreading ridges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H34C..03L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H34C..03L"><span id="translatedtitle">An Experimental Study on Using Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> to Trace Non-point source Phosphorous LossA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liang, T.</p> <p>2011-12-01</p> <p>Controlling phosphorous (P) inputs through management of its sources and transport is critical for limiting freshwater eutrophication. Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have been successfully used in the analysis of soil erosion and pollutant sources, as well as in the analysis of mineral genesis. To better understand the potential for REE use in tracing non-point sources of P, we examined the combined fate of REEs and P in Chinese soils amended with REEs and documented the formation of REE-P compounds. Laboratory leaching experiments and artificial simulated rainfall experiments were conducted. Vertical leaching transfers of REEs and P were relatively small, with transport depths less than 6 cm for most REEs and P. Export of applied REEs in leachate accounted for less that 5% of inputs. The vertical mobility order of REEs and P in Chinese soils was greatest for purple soil, followed by terra nera soil, then red soil, followed by cinnamon soil, and finally loess soil. Losses of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and P in surface runoff exhibited a parabolic relationship to simulated rainfall intensity. With greater exogenous La application, the amount of water soluble P, bicarbonate-extractable P and hydroxide-extractable P decreased significantly, while acid-extractable and residual forms of P increased significantly. In addition, characteristics of exogenous rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and P and their losses with surface runoff (both in the water and sediments) during simulated rainfall experiments (83 mm h-1) were investigated. The results revealed that most REEs (La, 94%; Nd, 93%; Sm, 96%) and P (96%) transported with sediments in the runoff. The total amounts of losses of REEs and P in the runoff were significantly correlated, suggesting the possibility of using REEs to trace the fate of agricultural nonpoint P losses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70125971','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70125971"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> (Li, Ba, Sr, and Rb) using Curiosity's ChemCam: early results for Gale crater from Bradbury Landing Site to Rocknest</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ollila, Ann M.; Newsom, Horton E.; Clark, Benton, III; Wiens, Roger C.; Cousin, Agnes; Blank, Jen G.; Mangold, Nicolas; Sautter, Violaine; Maurice, Sylvestre; Clegg, Samuel M.; Gasnault, Olivier; Forni, Olivier; Tokar, Robert; Lewin, Eric; Dyar, M. Darby; Lasue, Jeremie; Anderson, Ryan; McLennan, Scott M.; Bridges, John; Vaniman, Dave; Lanza, Nina; Fabre, Cecile; Melikechi, Noureddine; Perett, Glynis M.; Campbell, John L.; King, Penelope L.; Barraclough, Bruce; Delapp, Dorothea; Johnstone, Stephen; Meslin, Pierre-Yves; Rosen-Gooding, Anya; Williams, Josh</p> <p>2013-01-01</p> <p>The ChemCam instrument package on the Mars rover, Curiosity, provides new capabilities to probe the abundances of certain trace <span class="hlt">elements</span> in the rocks and soils on Mars using the laser-induced breakdown spectroscopy technique. We focus on detecting and quantifying Li, Ba, Rb, and Sr in targets analyzed during the first 100 sols, from Bradbury Landing Site to Rocknest. Univariate peak area models and multivariate partial least squares models are presented. Li, detected for the first time directly on Mars, is generally low (100 ppm and >1000 ppm, respectively. These analysis locations tend to have high Si and alkali abundances, consistent with a feldspar composition. Together, these trace <span class="hlt">element</span> observations provide possible evidence of magma differentiation and aqueous alteration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Litho.170...35G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Litho.170...35G"><span id="translatedtitle">U-Pb dates and trace-<span class="hlt">element</span> <span class="hlt">geochemistry</span> of zircon from migmatite, Western Gneiss Region, Norway: Significance for history of partial melting in continental subduction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gordon, Stacia M.; Whitney, Donna L.; Teyssier, Christian; Fossen, Haakon</p> <p>2013-06-01</p> <p>The Western Gneiss Region (WGR), Norway, is dominated by migmatitic gneiss that contains inclusions of eclogite, some of which contain evidence for ultrahigh-pressure metamorphism. To evaluate geochemical and age relationships between host migmatite and eclogite, we obtained LA-ICP-MS U-Pb dates and trace-<span class="hlt">element</span> analyses for zircon from a variety of textural types of leucosome, from layer-parallel to crosscutting. Zircon textures (euhedral, oscillatory- and sector-zone grains) indicate a likely magmatic origin of the leucosomes. Caledonian U-Pb zircon dates from zircon rim and near-rim regions are as old as 410-406 Ma, coeval with previously determined ages of high- and ultrahigh-pressure metamorphism of WGR eclogite. Trace-<span class="hlt">element</span> analyses obtained simultaneously with U-Pb dates indicate crystallization of zircon under garnet-present conditions in the majority of leucosomes. Other zircons, including those from crosscutting pegmatite, yield younger ages (as young as 385 Ma), coinciding with dates determined for amphibolite-facies retrogression of eclogite; trace-<span class="hlt">element</span> analyses suggest that these zircons grew under plagioclase-present (garnet-absent) conditions. Combined age and trace-<span class="hlt">element</span> data for leucosome zircons record the transition from high-pressure (garnet-present, plagioclase-absent) crystallization to lower-pressure (plagioclase-present) crystallization. If the euhedral zircons that yield ages coeval with peak or near-peak UHP metamorphism represent crystallization from anatectic leucosomes, these results, combined with field and petrographic observations of eclogite-migmatite relationships, are consistent with the presence of partially molten crust in at least part of the WGR during continental subduction. The decreased viscosity and increased buoyancy and strain weakening associated with partial melting may have assisted the rapid ascent of rocks from mantle to crustal depths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017502','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017502"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> contents and multiple mantle sources of the transform-related Mount Edgecumbe basalts, southeastern Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Riehle, J.R.; Budahn, J.R.; Lanphere, M.A.; Brew, D.A.</p> <p>1994-01-01</p> <p>Pleistocene basalt of the Mount Edgecumbe volcanic field (MEF) is subdivided into a plagioclase type and an olivine type. Th/La ratios of plagioclase basalt are similar to those of mid-ocean-ridge basalt (MORB), whereas those of olivine basalt are of continental affinity. Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) contents of the olivine basalt, which resemble those of transitional MORB, are modelled by 10-15% partial melting of fertile spinel-plagioclase lherzolite followed by removal of 8-13% olivine. It is concluded that olivine basalt originated in subcontinental spinel lherzolite and that plagioclase basalt may have originated in suboceanic lithosphere of the Pacific plate. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003TrGeo...5..225G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003TrGeo...5..225G"><span id="translatedtitle">Trace <span class="hlt">Elements</span> in River Waters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaillardet, J.; Viers, J.; Dupré, B.</p> <p>2003-12-01</p> <p>Trace <span class="hlt">elements</span> are characterized by concentrations lower than 1 mg L-1 in natural waters. This means that trace <span class="hlt">elements</span> are not considered when "total dissolved solids" are calculated in rivers, lakes, or groundwaters, because their combined mass is not significant compared to the sum of Na+, K+, Ca2+, Mg2+, H4SiO4, HCO3-, CO32-, SO42-, Cl-, and NO3-. Therefore, most of the <span class="hlt">elements</span>, except about ten of them, occur at trace levels in natural waters. Being trace <span class="hlt">elements</span> in natural waters does not necessarily qualify them as trace <span class="hlt">elements</span> in rocks. For example, aluminum, iron, and titanium are major <span class="hlt">elements</span> in rocks, but they occur as trace <span class="hlt">elements</span> in waters, due to their low mobility at the <span class="hlt">Earth</span>'s surface. Conversely, trace <span class="hlt">elements</span> in rocks such as chlorine and carbon are major <span class="hlt">elements</span> in waters.The <span class="hlt">geochemistry</span> of trace <span class="hlt">elements</span> in river waters, like that of groundwater and seawater, is receiving increasing attention. This growing interest is clearly triggered by the technical advances made in the determination of concentrations at lower levels in water. In particular, the development of inductively coupled plasma mass spectrometry (ICP-MS) has considerably improved our knowledge of trace-<span class="hlt">element</span> levels in waters since the early 1990s. ICP-MS provides the capability of determining trace <span class="hlt">elements</span> having isotopes of interest for geochemical dating or tracing, even where their dissolved concentrations are extremely low.The determination of trace <span class="hlt">elements</span> in natural waters is motivated by a number of issues. Although rare, trace <span class="hlt">elements</span> in natural systems can play a major role in hydrosystems. This is particularly evident for toxic <span class="hlt">elements</span> such as aluminum, whose concentrations are related to the abundance of fish in rivers. Many trace <span class="hlt">elements</span> have been exploited from natural accumulation sites and used over thousands of years by human activities. Trace <span class="hlt">elements</span> are therefore highly sensitive indexes of human impact from local to global scale. Pollution impact studies require knowledge of the natural background concentrations and knowledge of pollutant behavior. For example, it is generally accepted that rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in waters behave as good analogues for the actinides, whose natural levels are quite low and rarely measured. Water quality investigations have clearly been a stimulus for measurement of toxic heavy metals in order to understand their behavior in natural systems.From a more fundamental point of view, it is crucial to understand the behavior of trace <span class="hlt">elements</span> in geological processes, in particular during chemical weathering and transport by waters. Trace <span class="hlt">elements</span> are much more fractionated by weathering and transport processes than major <span class="hlt">elements</span>, and these fractionations give clues for understanding the nature and intensity of the weathering+transport processes. This has not only applications for weathering studies or for the past mobilization and transport of <span class="hlt">elements</span> to the ocean (potentially recorded in the sediments), but also for the possibility of better utilization of trace <span class="hlt">elements</span> in the aqueous environment as an exploration tool.In this chapter, we have tried to review the recent literature on trace <span class="hlt">elements</span> in rivers, in particular by incorporating the results derived from recent ICP-MS measurements. We have favored a "field approach" by focusing on studies of natural hydrosystems. The basic questions which we want to address are the following: What are the trace <span class="hlt">element</span> levels in river waters? What controls their abundance in rivers and fractionation in the weathering+transport system? Are trace <span class="hlt">elements</span>, like major <span class="hlt">elements</span> in rivers, essentially controlled by source-rock abundances? What do we know about the chemical speciation of trace <span class="hlt">elements</span> in water? To what extent do colloids and interaction with solids regulate processes of trace <span class="hlt">elements</span> in river waters? Can we relate the <span class="hlt">geochemistry</span> of trace <span class="hlt">elements</span> in aquatic systems to the periodic table? And finally, are we able to satisfactorily model and predict the behavior of most of the trace <span class="hlt">elements</span> </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://isotope.colorado.edu/~mojzsis/2007_Trail_Gcubed.pdf','EPRINT'); return false;" href="http://isotope.colorado.edu/~mojzsis/2007_Trail_Gcubed.pdf"><span id="translatedtitle">Constraints on Hadean zircon protoliths from oxygen isotopes, Ti-thermometry, and rare <span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Mojzsis, Stephen J.</p> <p></p> <p>zircon oxygen isotope ratios and reconnaissance Ti-in-zircon concentrations, guidedConstraints on Hadean zircon protoliths from oxygen isotopes, Ti-thermometry, and rare <span class="hlt">earth</span> Australia. Zircon oxygen isotope results bolster the view that some Hadean (>3.85 Ga) zircon source melts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dspace.cam.ac.uk/handle/1810/246646','EPRINT'); return false;" href="http://www.dspace.cam.ac.uk/handle/1810/246646"><span id="translatedtitle">Partitioning of light lithophile <span class="hlt">elements</span> during basalt eruptions on <span class="hlt">Earth</span> and application to Martian shergottites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Edmonds, Marie</p> <p>2014-12-18</p> <p>Cosmochimica Acta 60, 3267-3283. 548 Whitworth, M.P., Rankin, A.H., 1989. Evolution of fluid phases associated with lithium 549 pegmatites from SE Ireland. Mineral. Mag 53, 271-284. 550 Wood, B.J., Blundy, J.D., 1997. A predictive model for rare <span class="hlt">earth</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=233107','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=233107"><span id="translatedtitle">Mixing rare <span class="hlt">earth</span> <span class="hlt">elements</span> with manures to control phosphorus loss in runoff and track manure fate</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Concern over the enrichment of agricultural runoff with phosphorus (P) from land applied livestock manures has prompted the development of manure amendments that minimize P solubility. We evaluated the effect of mixing two rare <span class="hlt">earth</span> chlorides, lanthanum chloride and ytterbium chloride, with poultr...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24793516','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24793516"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in intertidal sediments of Bohai Bay, China: concentration, fractionation and the influence of sediment texture.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yong; Gao, Xuelu; Arthur Chen, Chen-Tung</p> <p>2014-07-01</p> <p>Surface sediments from intertidal Bohai Bay were assessed using a four-step sequential extraction procedure to determine their concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and the chemical forms in which those <span class="hlt">elements</span> were present. The normalized ratios La/Gd and La/Yb showed that LREE contents were not significantly higher than the middle REEs or HREE contents. A negative Ce anomaly and positive Eu were observed in sand and silty sand sediments, whereas no significant Ce or Eu anomaly was found in clayey silt sediments. Residual fraction of REEs accounted for the majority of their total concentrations. Middle REEs were more easily leached than other REEs, especially in clayey silt sediment. REEs contents in the surface sediment from the intertidal Bohai Sea were consistent with data from the upper continental crust and China shallow sea sediments, indicating that they were generally unaffected by heavily anthropogenic effects from adjacent areas. PMID:24793516</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011480','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011480"><span id="translatedtitle">Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in geological materials by inductively coupled argon plasma/atomic emission spectrometry</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Crock, J.G.; Lichte, F.E.</p> <p>1982-01-01</p> <p>Inductively coupled argon plasma/optical emission spectrometery (ICAP/OES) is useful as a simultaneous, multielement analytical technique for the determination of trace <span class="hlt">elements</span> in geological materials. A method for the determination of trace-level rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in geological materials using an ICAP 63-channel emission spectrometer is described. Separation and preconcentration of the REE and yttrium from a sample digest are achieved by a nitric acid gradient cation exchange and hydrochloric acid anion exchange. Precision of 1-4% relative standard deviation and comparable accuracy are demonstrated by the triplicate analysis of three splits of BCR-1 and BHVO-1. Analyses of other geological materials including coals, soils, and rocks show comparable precision and accuracy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V41A4782S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V41A4782S"><span id="translatedtitle">Determination of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Green River Shale By Inductively Coupled Plasma Mass Spectrometry Using a Desolvating Nebulizer System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, F.; Clarke, D.; Moody, S.</p> <p>2014-12-01</p> <p>In this work, inductively coupled plasma mass spectrometry (ICP-MS) is applied to a geological sample for the determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) using a specialized nebulizer system. The low flow desolvating nebulizer has been shown to decrease metal oxide formation which leads to a reduction in mass spectral interferences. Traditional nebulizers and spray chambers may be suitable for similar sample types, but reduction of water vapor loading to the plasma can improve REE detection limits for quadrupole-based ICP-MS. The Green River formation holds the largest oil shale deposits in the world and understanding the <span class="hlt">elemental</span> composition of these samples is important in its study. A certified reference material, USGS Green River Shale (SGR-1), was microwave digested prior to analysis, and recoveries of REEs compared to historical values are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V31C4763H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V31C4763H"><span id="translatedtitle">Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span> of Basaltic Tephra in Maar Cores; Implications for Centre Correlation, Field Evolution, and Mantle Source Characteristics of the Auckland Volcanic Field, New Zealand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hopkins, J. L.; Leonard, G.; Timm, C.; Wilson, C. J. N.; Neil, H.; Millet, M. A.</p> <p>2014-12-01</p> <p>Establishing volcanic hazard and risk management strategies hinges on a detailed understanding of the type, timing and tephra dispersal of past eruptions. In order to unravel the pyroclastic eruption history of a volcanic field, genetic links between the deposits and eruption source centre need to be established. The Auckland Volcanic Field (AVF; New Zealand) has been active for ca. 200 kyr and comprises ca. 53 individual centres covering an area of ca. 360km2. These centres show a range of sizes and eruptive styles from maar craters and tuff rings, to scoria cones and lava flows consistent with both phreatomagmatic and magmatic eruptions. Superimposition of the metropolitan area of Auckland (ca. 1.4 million inhabitants) on the volcanic field makes it critically important to assess the characteristics of the volcanic activity, on which to base assessment and management of the consequent hazards. Here we present a geochemical approach for correlating tephra deposits to their source centres. To acquire the most complete stratigraphic record of pyroclastic events, maar crater cores from different locations, covering various depths and thus ages across the field were selected. Magnetic susceptibility and x-ray density scanning of the cores was used to identify the basaltic tephra horizons, which were sampled and in-situ analysis of individual shards undertaken for major and trace <span class="hlt">elements</span> using EPMA and LA-ICP-MS techniques, respectively. Our results show that tephra shard trace <span class="hlt">element</span> ratios are comparable and complementary to the AVF whole rock database. The use of specific trace <span class="hlt">element</span> ratios (e.g. Gd/Yb vs. Zr/Yb) allows us to fingerprint and cross correlate tephra horizons between cores and, when coupled with newly acquired 40Ar-39Ar age dating and eruption size estimates, correlate horizons to their source centres. This integrated style of study can provide valuable information to help volcanic hazard management and forecasting, and mitigation of related risks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.T11B2316G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T11B2316G"><span id="translatedtitle">Trace <span class="hlt">element</span> and isotopic <span class="hlt">geochemistry</span> of Franciscan graywackes with implications for short time of recycling of detritus and interaction of continental sediments with metabasites during subduction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghatak, A.; Basu, A. R.; Wakabayashi, J.</p> <p>2011-12-01</p> <p>Trace <span class="hlt">element</span> concentrations and Nd-Sr-Pb-isotopic ratios of graywackes from the Franciscan subduction complex appear to reflect two geochemically distinct sources. Some of the graywackes show no negative Eu-anomaly (Eu/Eu* >0.9), slightly concave up heavy REE, and generally arc-like trace <span class="hlt">element</span> patterns. These graywackes have Western Pacific intra-oceanic arc-like Pb-isotopic ratios, probably reflecting derivation from older accreted oceanic arc terranes and supra-subduction zone ophiolites that are common in the Sierra Nevada-Klamath Mountains region. Other graywackes display small but distinctly negative Eu-anomalies (Eu/Eu* <0.9) with Post-Archean Australian Shale (PAAS) like trace <span class="hlt">element</span> patterns and Pb-isotopic compositions similar to the Sierra Nevada granitic rocks. Although the latter continental arc signature may be expected to typify the younger graywacke samples, there is no systematic separation of these two geochemical groups by age. The two youngest samples fall into the oceanic arc group. In addition, all the graywackes show distinctly gradual light REE depletions from La to Sm when normalized to PAAS. Thus the geochemical characteristics may reflect variation in location of sediment delivery and distributary systems and/or reworking of previously accreted Franciscan materials, rather than progressive unroofing of the Sierra Nevada batholith. Comparison of our data with published data on the forearc basin deposits of the Great Valley Group suggests the same sediment sources. The derivation of trench sediments (subduction complex graywacke) and forearc basin deposits from the same sources precludes a significant exotic source for Franciscan graywackes as proposed in the past by some researchers. The systematic variation of Nd and Sr isotopic composition with age for our Franciscan graywacke samples also mimics the trends of coeval Great Valley Group rocks, in spite of widespread evidence of significant reworking of the detritus which result in Franciscan isotopic compositions resembling older Great Valley Group rocks. Although there is much scatter in the collective dataset, these results suggest that the burial-exhumation cycles that recycled Franciscan clastic material were short lived. A comparison of the trace <span class="hlt">element</span> and isotopic ratios of the Franciscan graywackes with those of Franciscan metabasites reaffirms the conclusion in several of our recent studies that the metabasites were not chemically modified by interaction with fluids derived from continental sediments during subduction and exhumation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMPP13A1855S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMPP13A1855S"><span id="translatedtitle">High-resolution Carbon and Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span> in Early-Middle Aptian Organic-Rich Sediments of the El Pui section, Cataluña, Spain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanchez-Hernandez, Y.; Maurrasse, F. J.</p> <p>2013-12-01</p> <p>Darker and more expanded layers characterize the interval of the El Pui section, Organyà Basin that correlates with the early-middle Aptian. They contrast with the earlier levels from the latest Barremian to the earliest Aptian interval, suggesting intensified OM sequestration in the superjacent layers. Accentuated conditions conducive to increased OM accumulation are revealed in the high-resolution ?13Corg curve that corroborates intensified primary productivity as seen elsewhere. Increasing trends in <span class="hlt">elemental</span> concentrations of Al, Si and Ti normalized with respect to TIC, further support the changing conditions and sustained transport of terrestrial material to the basin. Similarly, clay minerals results indicate intensified breakdown of continental rocks and rapid burial of clay. Enrichment of redox-sensitive trace <span class="hlt">elements</span> (Ni, V, Co, Cr, U, and Th) at certain levels attests that concurrent reducing conditions prevailed, culminating with temporal development of an anoxic phase. Microfacies characterized by rare to absent benthic fauna are in agreement with the geochemical results suggesting stressful bottom water conditions marked by oxygen deficiency. The integrated results thus indicate that existent intermittent oxygen-depleted conditions in sediments of the El Pui section became accentuated during the early Aptian leading to enhanced OM sequestration. Intensified global paleoceanographic and paleoclimatic changes in the early Aptian, superimposed on specific physiographic characteristics of the semi-enclosed basin and its adjacent landmasses, may have resulted in intensified nutrient delivery to the basin, increased productivity, and water column stratification that caused severe oxygen depletion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JAESc..34..123P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JAESc..34..123P"><span id="translatedtitle">The behaviour of trace and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) during hydrothermal alteration in the Rangan area (Central Iran)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parsapoor, A.; Khalili, M.; Mackizadeh, M. A.</p> <p>2009-02-01</p> <p>The rhyolitic dome in the Rangan area has been subjected to hydrothermal alterations by two different systems, (1) A fossil magmatic-hydrothermal system with a powerful thermal engine of a deep monzodioritic magma, (2) An active hydrothermal system dominated by meteoric water. Based on mineralogical and geochemical studies, three different alteration facies have been identified (phyllic, advanced argillic and silicic) with notable differences in REE and other trace <span class="hlt">elements</span> behaviour. In the phyllic alteration zone with assemblage minerals such as sericite, pyrite, quartz, kaolinite, LREE are relatively depleted whereas HREE are enriched. The advanced argillic zone is identified by the presence of alunite-jarosite and pyrophyllite as well as immobility of LREE and depletion in HREE. In the silicic zone, most of LREE are depleted but HREE patterns are unchanged compared to their fresh rock equivalents. All the REE fractionation ratios (La/Yb) cn, (La/Sm) cn, (Tb/Yb) cn, (Ce/Ce ?) cn and (Eu/Eu ?) cn are low in the phyllic altered facies. (Eu/Eu ?) cn in both advanced and silicic facies is low too. In all alteration zones, high field strength <span class="hlt">elements</span> (HFSE) (e.g. Ti, Zr, Nb) are depleted whereas transition <span class="hlt">elements</span> (e.g. V, Cr, Co, Ni, Fe) are enriched. Geochemically speaking, trace and rare <span class="hlt">earth</span> <span class="hlt">elements</span> behave highly selective in different facies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21438595','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21438595"><span id="translatedtitle">Global in-use stocks of the rare <span class="hlt">Earth</span> <span class="hlt">elements</span>: a first estimate.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Du, Xiaoyue; Graedel, T E</p> <p>2011-05-01</p> <p>Even though rare <span class="hlt">earth</span> metals are indispensible in modern technology, very little quantitative information other than combined rare <span class="hlt">earth</span> oxide extraction is available on their life cycles. We have drawn upon published and unpublished information from China, Japan, the United States, and elsewhere to estimate flows into use and in-use stocks for 15 of the metals: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Here, we show that the combined flows into use comprised about 90 Gg in 2007; the highest for individual metals were ?28 Gg Ce and ?22 Gg La, the lowest were ?0.16 Gg Tm and ?0.15 Gg Lu. In-use stocks ranged from 144 Gg Ce to 0.2 Gg Tm; these stocks, if efficiently recycled, could provide a valuable supplement to geological stocks. PMID:21438595</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810040416&hterms=Phosphorus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DPhosphorus','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810040416&hterms=Phosphorus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DPhosphorus"><span id="translatedtitle">Halogen and phosphorus storage in the <span class="hlt">earth</span>. [<span class="hlt">elemental</span> spatial distribution from geochemical, geophysical, and cosmochemical factors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, J. V.</p> <p>1981-01-01</p> <p>Chemical analyses of surface reservoirs, coupled with compositions for interior zones inferred from geophysical and geochemical data have been used to obtain a range of estimates of the bulk composition of the <span class="hlt">earth</span>. It is suggested that (1) apatite with 3 wt% Fe, up to 1 wt% Cl, and 0.003 wt% Br is the principal mineral reservoir for halogens, and mica is a subsidiary reservoir; (2) apatite with 18 wt% P is the principal store of P in the upper mantle and perhaps lower mantle, but accounts for only one-twentieth of P in the <span class="hlt">earth</span>; and (3) the remaining P is in a reservoir inaccessible to magmatism, and may amount to a maximum of 0.7 wt% in the core.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014010','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014010"><span id="translatedtitle">The group separation of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> and yttrium from geologic materials by cation-exchange chromatography</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Crock, J.G.; Lichte, F.E.; Wildeman, T.R.</p> <p>1984-01-01</p> <p>Demand is increasing for the determination of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (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 <span class="hlt">elements</span> from the host-rock matrix. Two separate gradient strong-acid cation-exchange procedures were characterized and the major <span class="hlt">elements</span> as well as those <span class="hlt">elements</span> 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 <span class="hlt">elements</span> 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 <span class="hlt">elements</span>. ?? 1984.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16289225','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16289225"><span id="translatedtitle">Effect of earthworms (Eisenia fetida) on the fractionation and bioavailability of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in nine Chinese soils.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wen, Bei; Liu, Ying; Hu, Xiao-yu; Shan, Xiao-quan</p> <p>2006-05-01</p> <p>The effect of earthworm (Eisenia fetida) activity on soil pH, dissolved organic carbon (DOC), fraction distribution pattern and bioavailability of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) Y, La, Ce, Pr and Nd in nine Chinese soils were investigated using pot experiments. A three-step extraction procedure recommended by the European Community (Standards, Measurements and Testing Programme) was used to fractionate REEs in soils into water soluble, exchangeable and carbonate bound (B1), Fe- and Mn-oxides bound (B2) and organic matter and sulfide bound (B3). Inoculated with earthworms, the soil pH, DOC and water-soluble rare <span class="hlt">earth</span> <span class="hlt">elements</span> fraction increased. A significant correlation was obtained between the increased DOC and the increased water-soluble REEs. REEs in fraction B1 increased after earthworm inoculation, while those in fraction B3 decreased. No significant differences were observed for REEs in fraction B2. The biomass and the concentrations of REEs in wheat shoots and roots increased after the treatment with earthworms. The results demonstrated that earthworm activity increased the mobility and bioavailability of REEs in soils. PMID:16289225</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/pp/p1596/p1596.html','USGSPUBS'); return false;" href="http://pubs.usgs.gov/pp/p1596/p1596.html"><span id="translatedtitle">Geochemical studies of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Portuguese pyrite belt, and geologic and geochemical controls on gold distribution</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grimes, David J.; Earhart, Robert L.; de Carvalho, Delfim; Oliveira, Vitor; Oliveira, Jose T.; Castro, Paulo</p> <p>1998-01-01</p> <p>This report describes geochemical and geological studies which were conducted by the U.S. Geological Survey (USGS) and the Servicos Geologicos de Portugal (SPG) in the Portuguese pyrite belt (PPB) in southern Portugal. The studies included rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) distributions and geological and geochemical controls on the distribution of gold. Rare <span class="hlt">earth</span> <span class="hlt">element</span> distributions were determined in representative samples of the volcanic rocks from five west-trending sub-belts of the PPB in order to test the usefulness of REE as a tool for the correlation of volcanic events, and to determine their mobility and application as hydrothermal tracers. REE distributions in felsic volcanic rocks show increases in the relative abundances of heavy REE and a decrease in La/Yb ratios from north to south in the Portuguese pyrite belt. Anomalous amounts of gold are distributed in and near massive and disseminated sulfide deposits in the PPB. Gold is closely associated with copper in the middle and lower parts of the deposits. Weakly anomalous concentrations of gold were noted in exhalative sedimentary rocks that are stratigraphically above massive sulfide deposits in a distal manganiferous facies, whereas anomalously low concentrations were detected in the barite-rich, proximal-facies exhalites. Altered and pyritic felsic volcanic rocks locally contain highly anomalous concentrations of gold, suggesting that disseminated sulfide deposits and the non-ore parts of massive sulfide deposits should be evaluated for their gold potential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhyB..381..144A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhyB..381..144A"><span id="translatedtitle">Spectroscopic and electrical properties of Mg Ti ferrite doped with different rare-<span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ahmed, M. A.; Ateia, E.; Salem, F. M.</p> <p>2006-05-01</p> <p>The dielectric constant ( ??), and the electric conductivity ( ?) for Mg 1+xTi xR yFe 2-2x-yO 4, 0.025? y?0.15 doped with different rare-<span class="hlt">earth</span> ions, R=Er, Ce and Nd, were measured in the temperature range 300-750 K. The measurements were carried out as a function of frequency 50-1000 kHz X-ray diffractograms and IR spectra revealed that all the investigated samples posses the spinel structure. More than one conduction mechanism is used to interpret the electrical measurements. The most predominant one is the hopping mechanism that occurs between the ions of different valences existing on the same and different sites. All the ionic radii of the rare-<span class="hlt">earth</span> used are too large to occupy the octahedral site. They form secondary phases on the grain boundaries. The electrical properties show that the pure sample has a larger dielectric constant as well as a larger valence exchange with respect to any doped one. This means that introducing rare-<span class="hlt">earth</span> ions into the samples decreases ?? and increases the resistivity, owing to the decreasing Fe-Fe interaction. This feature can help to obtain well applicable ferrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.umanitoba.ca/faculties/science/geological_sciences/faculty/arc/pictures/Rare_Element_Deposits-ToG-2014.pdf','EPRINT'); return false;" href="http://www.umanitoba.ca/faculties/science/geological_sciences/faculty/arc/pictures/Rare_Element_Deposits-ToG-2014.pdf"><span id="translatedtitle">13.21 <span class="hlt">Geochemistry</span> of the Rare-<span class="hlt">Earth</span> <span class="hlt">Element</span>, Nb, Ta, Hf, and Zr Deposits RL Linnen, University of Western Ontario, London, ON, Canada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Chakhmouradian, Anton</p> <p></p> <p>557 13.21.3.3 Peraluminous Granite- and Pegmatite-Hosted Deposits 559 13.21.3.3.1 Peraluminous granite-hosted deposits 559 13.21.3.3.2 Peraluminous pegmatite-hosted deposits 559 13.21.3.4 Supergene Deposits 560 13</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.era.lib.ed.ac.uk/handle/1842/5934','EPRINT'); return false;" href="http://www.era.lib.ed.ac.uk/handle/1842/5934"><span id="translatedtitle">Evolution of the <span class="hlt">Earth</span>'s mantle-crust-atmosphere system from the trace <span class="hlt">element</span> and isotope <span class="hlt">geochemistry</span> of the plume-mantle reservoir </span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Starkey, Natalie</p> <p>2009-11-26</p> <p>The 62 million year old lava flows of Baffin Island and West Greenland represent the earliest phase of magmatism in the North Atlantic Igneous Province (NAIP). These picritic lavas are characterised by high magnesium ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRE..119..255O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRE..119..255O"><span id="translatedtitle">Trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> (Li, Ba, Sr, and Rb) using Curiosity's ChemCam: Early results for Gale crater from Bradbury Landing Site to Rocknest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ollila, Ann M.; Newsom, Horton E.; Clark, Benton; Wiens, Roger C.; Cousin, Agnes; Blank, Jen G.; Mangold, Nicolas; Sautter, Violaine; Maurice, Sylvestre; Clegg, Samuel M.; Gasnault, Olivier; Forni, Olivier; Tokar, Robert; Lewin, Eric; Dyar, M. Darby; Lasue, Jeremie; Anderson, Ryan; McLennan, Scott M.; Bridges, John; Vaniman, Dave; Lanza, Nina; Fabre, Cecile; Melikechi, Noureddine; Perrett, Glynis M.; Campbell, John L.; King, Penelope L.; Barraclough, Bruce; Delapp, Dorothea; Johnstone, Stephen; Meslin, Pierre-Yves; Rosen-Gooding, Anya; Williams, Josh</p> <p>2014-01-01</p> <p>ChemCam instrument package on the Mars rover, Curiosity, provides new capabilities to probe the abundances of certain trace <span class="hlt">elements</span> in the rocks and soils on Mars using the laser-induced breakdown spectroscopy technique. We focus on detecting and quantifying Li, Ba, Rb, and Sr in targets analyzed during the first 100 sols, from Bradbury Landing Site to Rocknest. Univariate peak area models and multivariate partial least squares models are presented. Li, detected for the first time directly on Mars, is generally low (<15 ppm). The lack of soil enrichment in Li, which is highly fluid mobile, is consistent with limited influx of subsurface waters contributing to the upper soils. Localized enrichments of up to ~60 ppm Li have been observed in several rocks but the host mineral for Li is unclear. Bathurst_Inlet is a fine-grained bedrock unit in which several analysis locations show a decrease in Li and other alkalis with depth, which may imply that the unit has undergone low-level aqueous alteration that has preferentially drawn the alkalis to the surface. Ba (~1000 ppm) was detected in a buried pebble in the Akaitcho sand ripple and it appears to correlate with Si, Al, Na, and K, indicating a possible feldspathic composition. Rb and Sr are in the conglomerate Link at abundances >100 ppm and >1000 ppm, respectively. These analysis locations tend to have high Si and alkali abundances, consistent with a feldspar composition. Together, these trace <span class="hlt">element</span> observations provide possible evidence of magma differentiation and aqueous alteration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Plate+AND+Tectonics&pg=7&id=EJ032449','ERIC'); return false;" href="http://eric.ed.gov/?q=Plate+AND+Tectonics&pg=7&id=EJ032449"><span id="translatedtitle"><span class="hlt">Earth</span> Science in 1970</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Geotimes, 1971</p> <p>1971-01-01</p> <p>Reviews advancements in <span class="hlt">earth</span> science during 1970 in each of these areas: economic geology (fuels), economic geology (metals), economic geology (nonmetals), environmental geology, <span class="hlt">geochemistry</span>, manpower, hydrology, mapping, marine geology, mineralogy, paleontology, plate tectonics, politics and geology, remote sensing, and seismology. (PR)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JVGR..178..224T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JVGR..178..224T"><span id="translatedtitle">Major and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of neutral and acidic thermal springs at El Chichón volcano, Mexico: Implications for monitoring of the volcanic activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taran, Y.; Rouwet, D.; Inguaggiato, S.; Aiuppa, A.</p> <p>2008-12-01</p> <p>Four groups of thermal springs with temperatures from 50 to 80 °C are located on the S-SW-W slopes of El Chichón volcano, a composite dome-tephra edifice, which exploded in 1982 with a 1 km wide, 160 m deep crater left. Very dynamic thermal activity inside the crater (variations in chemistry and migration of pools and fumaroles, drastic changes in the crater lake volume and chemistry) contrasts with the stable behavior of the flank hot springs during the time of observations (1974-2005). All known groups of hot springs are located on the contact of the basement and volcanic edifice, and only on the W-SW-S slopes of the volcano at almost same elevations 600-650 m asl and less than 3 km of direct distance from the crater. Three groups of near-neutral (pH ? 6) springs at SW-S slopes have the total thermal water outflow rate higher than 300 l/s and are similar in composition. The fourth and farthest group on the western slope discharges acidic (pH ? 2) saline (10 g/kg of Cl) water with a much lower outflow rate (< 10 l/s). Water-rock interaction modeling of main types of the El Chichón thermal waters using regular log Q/ K graphs (saturation indices vs temperature) showed maximum equilibrium temperature slightly higher than 200 °C. Acidic waters are equilibrated with some clay minerals at about 120 °C. Three main sources of the salinity of thermal water are suggested on the basis of mixing plots and isotopic data: a magmatic source for CO 2, boron, sulfur and a limited part of Cl; volcanic rock source for the major cations and trace <span class="hlt">elements</span>; the oil-bearing evaporitic basement source (oil-field brine?) for NaCl, Br, a part of Ca and some trace <span class="hlt">elements</span>. All flank thermal springs end up in the river Rio Magdalena that has a variable seasonal flow rates from 4 to 20 m 3/s. Any changes in the chemistry of springs must notably change the composition of the streams draining hot springs and eventually, Rio Magdalena. A monthly geochemical monitoring of Rio Magdalena and streams draining main hot springs would be a useful tool for surveying the activity of the volcano.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720018656','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720018656"><span id="translatedtitle">On the determination of the long period tidal perturbations in the <span class="hlt">elements</span> of artificial <span class="hlt">earth</span> satellites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musen, P.; Felsentreger, T.</p> <p>1972-01-01</p> <p>The magnitude of the tidal effects depends upon the elastic properties of the <span class="hlt">earth</span> as described by Love numbers. The Love numbers appear as the coefficients in the expansion of the exterior tidal potential in terms of spherical harmonics (in Maxwellian form). A single averaging process was performed only along the parallels of latitude. This process preserves additional long period tidal effects (with periods of a few days or more). It also eliminates the short period effects with periods of one day or less.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://arxiv.org/pdf/1311.5897.pdf','EPRINT'); return false;" href="http://arxiv.org/pdf/1311.5897.pdf"><span id="translatedtitle">New fission fragment distributions and r-process origin of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Goriely, S; Lemaitre, J -F; Panebianco, S; Dubray, N; Hilaire, S; Bauswein, A; Janka, H -Thomas</p> <p>2013-01-01</p> <p>Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process <span class="hlt">elements</span> with nuclear mass numbers A > 140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular the fission fragment yields determine the creation of 110 140.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=33914&keyword=cobalt&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=41779239&CFTOKEN=47051119','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=33914&keyword=cobalt&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=41779239&CFTOKEN=47051119"><span id="translatedtitle">COAL MINE RELATED STREAM SEDIMENT <span class="hlt">GEOCHEMISTRY</span> IN SOUTHERN ILLINOIS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>A regional survey in stream sediment <span class="hlt">geochemistry</span> indicates that downstream areas from coal mines or coal related land uses can contain four times the median value of several <span class="hlt">elements</span>, specifically cadmium cobalt, copper, iron, manganese, nickel and zinc. In those parts of a mine...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26305163','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26305163"><span id="translatedtitle">Alkaline-<span class="hlt">Earth</span>-Metal-Induced Liberation of Rare Allotropes of <span class="hlt">Elemental</span> Silicon and Germanium from N-Heterocyclic Metallylenes.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Blom, Burgert; Said, Amro; Szilvási, Tibor; Menezes, Prashanth W; Tan, Gengwen; Baumgartner, Judith; Driess, Matthias</p> <p>2015-09-01</p> <p>The synthesis and striking reactivity of the unprecedented N-heterocyclic silylene and germylene ("metallylene") alkaline-<span class="hlt">earth</span> metal (Ae) complexes of the type [(?(5)-C5Me5)2Ae?:E(N(t)BuCH)2] (3, 4, and 7-9; Ae = Ca, E = Ge 3; Ae = Sr, E = Ge 4; Ae = Sr, E = Si 7; Ae = Ba, E = Si 8; Ae = Ba, E = Ge 9) are reported. All complexes have been characterized by spectroscopic means, and their bonding situations investigated by density functional theory (DFT) methods. Single-crystal X-ray diffraction analyses of examples revealed relatively long Si-Ae and Ge-Ae distances, respectively, indicative of weak E:?Ae (E = Si, Ge) dative bonds, further supported by the calculated Wiberg bond indices , which are rather low in all cases (?0.5). Unexpectedly, the complexes undergo facile transformation to 1,4-diazabuta-1,3-diene Ae metal complexes of the type [(?(5)-C5Me5)2Ae(?(2)-{N(t)Bu?CHCH?N(t)Bu})] (Ae = Sr 10, Ae = Ba 11) or in the case of calcium to the dinuclear complex [(?(5)-C5Me5)2Ca?:N((t)Bu)?CHCH?((t)Bu)N:?Ca(?(5)-C5Me5)2] (12) under concomitant liberation of <span class="hlt">elemental</span> silicon and germanium. The formation of <span class="hlt">elemental</span> silicon and germanium is proven by inductively coupled plasma atomic emission spectroscopy, transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray spectroscopy. Notably, the decomposition of the Si(II)?Ba complex 8 produces allo-silicon, a rare allotropic form of <span class="hlt">elemental</span> silicon. Similarly, the analogous Ge(II)?Ba complex 9, upon decomposition, forms tetragonal germanium, a dense and rare allotrope of <span class="hlt">elemental</span> germanium. The energetics of this unprecedented alkaline-<span class="hlt">earth</span>-metal-induced liberation of <span class="hlt">elemental</span> silicon and germanium was additionally studied by DFT methods, revealing that the transformations are pronouncedly exergonic and considerably larger for the N-heterocyclic germylene complexes than those of the corresponding silicon analogues. PMID:26305163</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.100..158A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.100..158A"><span id="translatedtitle">Highly siderophile <span class="hlt">element</span> <span class="hlt">geochemistry</span> of peridotites and pyroxenites from Horní Bory, Bohemian Massif: Implications for HSE behaviour in subduction-related upper mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ackerman, Lukáš; Pitcher, Lynnette; Strnad, Ladislav; Puchtel, Igor S.; Jelínek, Emil; Walker, Richard J.; Rohovec, Jan</p> <p>2013-01-01</p> <p>Highly siderophile <span class="hlt">element</span> (HSE - Re, Os, Ir, Ru, Rh, Pd, Pt, and Au) and S abundances, sulphide petrography and 187Os/188Os compositions of two distinct suites - Mg-lherzolite and Fe-dunite/wehrlite accompanied by pyroxenites from Horní Bory, Bohemian Massif, Czech Republic are reported. The Mg-lherzolite suite is enriched in IPGE (Os, Ir, and Ru), moderately depleted in Pd, Pt and S, and has osmium isotopic compositions similar to that of the Phanerozoic convecting mantle. Such a composition can be best explained by reaction between previously depleted peridotite and sulphur-undersaturated melt at low melt-rock ratios. This reaction was associated with precipitation of IPGE alloys and Pt-As. The Fe-dunite/wehrlite suite is depleted in IPGE, enriched in Pd, Pt, and S and has radiogenic osmium isotopic compositions. The origin of this suite reflects melt-rock reaction between peridotite and subduction-related melt at high melt/rock ratios resulting in breakdown of primary sulphides and their replacement by HSE-poor but 187Os-enriched sulphides. Mass-balance calculations and relations between HSE and S contents show that, while most of the Re is trapped in base metal sulphides (BMS), only up to 28% of the rest of the HSE (Os, Ir, Ru, Pd, Pt) are accommodated in BMS. Several Pt-As phases discovered in Mg-lherzolite and Fe-dunite/wehrlite and Os-Ru phase found in Mg-lherzolite suggesting complex behaviour of HSE during melt-rock reactions depending on melt composition and melt/rock ratios. The Re-Os data for the Fe-wehrlite/dunite and pyroxenite rocks yield an errorchon age of 334 ± 19 Ma, which is similar to the age of other high temperature/pressure rocks from Gföhl Nappe (Moldanubian Zone, Bohemian Massif); this age likely corresponds to the time of melt-rock reactions and subduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H23F1336S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H23F1336S"><span id="translatedtitle">Fractionation of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> during Soil Formation along Feather River Basin Hillslopes in the California Sierra Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Steinert, T.; Weinman, B.; Yoo, K.; Mudd, S. M.; Kouba, C. M.; Maher, K.</p> <p>2013-12-01</p> <p>The mobility of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) has been debated by scientists for years. This study presents soil and soil moisture data from an ongoing study that examines how REEs fractionate as rock weathers into soil. The Middle Fork Feather River in Northern California, the location of the study site, takes advantage of an erosional signal propagating through the basin and compares traditional methods of REE normalization then contrasts them with <span class="hlt">elemental</span> losses based on mass balance calculations (tau). Analyzed by ICP-MS using the whole-rock Li-borate dissolution method, soil and water sample collection took place along two differentially eroding hill slopes (a shallow slope above the knick-point and a more inclined slope below the knick-point). Using Zr as an immobile <span class="hlt">element</span>, the mass-balance method clearly portrays REE fractionation occurring within the soils, whereas traditional REE normalization patterns do not clearly display fractionation relative to the parent material. While REEs fractionate approximately to the same extent in the topmost soils of both hill slopes, the more actively eroding hill slope fractionates REEs faster because of a faster rate of soil chemical weathering. While the full meaning of this work is still underway, current progress indicates that significant REE fractionation occurs during chemical weathering, implying that using REEs as tracers for surfaces processes requires significant care.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H52A..06N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H52A..06N"><span id="translatedtitle">Geochemical variations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in Marcellus shale flowback waters and multiple-source cores in the Appalachian Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Noack, C.; Jain, J.; Hakala, A.; Schroeder, K.; Dzombak, D. A.; Karamalidis, A.</p> <p>2013-12-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) - encompassing the naturally occurring lanthanides, yttrium, and scandium - are potential tracers for subsurface groundwater-brine flows and geochemical processes. Application of these <span class="hlt">elements</span> as naturally occurring tracers during shale gas development is reliant on accurate quantitation of trace metals in hypersaline brines. We have modified and validated a liquid-liquid technique for extraction and pre-concentration of REE from saline produced waters from shale gas extraction wells with quantitative analysis by ICP-MS. This method was used to analyze time-series samples of Marcellus shale flowback and produced waters. Additionally, the total REE content of core samples of various strata throughout the Appalachian Basin were determined using HF/HNO3 digestion and ICP-MS analysis. A primary goal of the study is to elucidate systematic geochemical variations as a function of location or shale characteristics. Statistical testing will be performed to study temporal variability of inter-<span class="hlt">element</span> relationships and explore associations between REE abundance and major solution chemistry. The results of these analyses and discussion of their significance will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26213134','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26213134"><span id="translatedtitle">Residential heating contribution to level of air pollutants (PAHs, major, trace, and rare <span class="hlt">earth</span> <span class="hlt">elements</span>): a moss bag case study.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vukovi?, Gordana; Uroševi?, Mira Ani?i?; Pergal, Miodrag; Jankovi?, Milan; Goryainova, Zoya; Tomaševi?, Milica; Popovi?, Aleksandar</p> <p>2015-12-01</p> <p>In areas with moderate to continental climates, emissions from residential heating system lead to the winter air pollution peaks. The EU legislation requires only the monitoring of airborne concentrations of particulate matter, As, Cd, Hg, Ni, and B[a]P. Transition metals and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) have also arisen questions about their detrimental health effects. In that sense, this study examined the level of extensive set of air pollutants: 16 polycyclic aromatic hydrocarbons (PAHs), and 41 major <span class="hlt">elements</span>, trace <span class="hlt">elements</span>, and REEs using Sphagnum girgensohnii moss bag technique. During the winter of 2013/2014, the moss bags were exposed across Belgrade (Serbia) to study the influence of residential heating system to the overall air quality. The study was set as an extension to our previous survey during the summer, i.e., non-heating season. Markedly higher concentrations of all PAHs, Sb, Cu, V, Ni, and Zn were observed in the exposed moss in comparison to the initial values. The patterns of the moss REE concentrations normalized to North American Shale Composite and Post-Archean Australian Shales were identical across the study area but enhanced by anthropogenic activities. The results clearly demonstrate the seasonal variations in the moss enrichment of the air pollutants. Moreover, the results point out a need for monitoring of air quality during the whole year, and also of various pollutants, not only those regulated by the EU Directive. PMID:26213134</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70118241','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70118241"><span id="translatedtitle">Origin of an unusual monazite-xenotime gneiss, Hudson Highlands, New York: SHRIMP U-Pb geochronology and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Aleinikoff, John N.; Grauch, Richard I.; Mazdab, Frank K.; Kwak, Loretta; Fanning, C. Mark; Kamo, Sandra L.</p> <p>2012-01-01</p> <p>A pod of monazite-xenotime gneiss (MXG) occurs within Mesoproterozoic paragneiss, Hudson Highlands, New York. This outcrop also contains granite of the Crystal Lake pluton, which migmatized the paragneiss. Previously, monazite, xenotime, and zircon from MXG, plus detrital zircon from the paragneiss, and igneous zircon from the granite, were dated using multi-grain thermal ionization mass spectrometry (TIMS). New SEM imagery of dated samples reveals that all minerals contain cores and rims. Thus TIMS analyses comprise mixtures of age components and are geologically meaningless. New spot analyses by sensitive high resolution ion microprobe (SHRIMP) of small homogeneous areas on individual grains allows deconvolution of ages within complexly zoned grains. Xenotime cores from MXG formed during two episodes (1034 ± 10 and 1014 ± 3 Ma), whereas three episodes of rim formation are recorded (999 ± 7, 961 ± 11, and 874 ± 11 Ma). Monazite cores from MXG mostly formed at 1004 ± 4 Ma; rims formed at 994 ± 4, 913 ± 7, and 890 ± 7 Ma. Zircon from MXG is composed of oscillatory-zoned detrital cores (2000-1170 Ma), plus metamorphic rims (1008 ± 7, 985 ± 5, and ?950 Ma). In addition, MXG contains an unusual zircon population composed of irregularly-zoned elongate cores dated at 1036 ± 5 Ma, considered to be the time of formation of MXG. The time of granite emplacement is dated by oscillatory-zoned igneous cores at 1058 ± 4 Ma, which provides a minimum age constraint for the time of deposition of the paragneiss. Selected trace <span class="hlt">elements</span>, including all REE plus U and Th, provide geochemical evidence for the origin of MXG. MREE-enriched xenotime from MXG are dissimilar from typical HREE-enriched patterns of igneous xenotime. The presence of large negative Eu anomalies and high U and Th in monazite and xenotime are uncharacteristic of typical ore-forming hydrothermal processes. We conclude that MXG is the result of unusual metasomatic processes during high grade metamorphism that was initiated at about 1035 Ma. This rock was then subjected to repeated episodes of dissolution/reprecipitation for about 150 m.y. during regional cooling of the Hudson Highlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V13D2630L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V13D2630L"><span id="translatedtitle">Evolution of ore forming fluid in the orogenic type gold deposit in Tavt, Mongolia: trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> and fluid inclusions in quartz</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, K.; Oyungerel, S.; Lee, I.</p> <p>2011-12-01</p> <p>The Tavt gold deposit of Dzhida-Selengisky metallogenic belt is located in the Dzhida terrane, northern Mongolia. This deposit commonly occurs with massive auriferous quartz veins that contain sulfides and less commonly occurs with disseminated- and stockwork-type quartz veins. Such gold-bearing quartz veins have an average grade of 6.3 g/t Au, 29.4 g/t Ag, and 1.3% Cu. This gold deposit is composed of three stages of quartz vein groups. The first stage quartz group is widely spread with medium to large grain size, showing white-grey and milky white colors. It underwent intensive cataclasis with strong cuts via fractures and includes a small amount of sulfides, secondary minerals and Au. The second stage quartz group is grey and includes an oxidation zone. The oxidation zone distributed on the outside of the vein is brown and green-grey; it is also enriched with sulfide minerals containing gold. This quartz group is located in a brittle and cataclastic zone with the first stage quartz group. The main mineralization process for gold is related to this second stage quartz group. The transition between the first and second groups is not clear, and their contact relationship is complex. The third stage quartz group is transparent to translucent, and has small euhedral crystals that were formed in the second stage quartz group. The third stage of quartz is partly associated with chlorite and montmorillonite that was formed in the latest stage. Each generation of quartz was analyzed by SEM-CL, EPMA, and ICP-MS. Fluid inclusion data were collected from the USGS gas-flow heating/freezing stage and Raman-spectroscopy. The electron microprobe data show the distribution of Al, Ca, K and Fe among distinguished CL intensities and textures of quartz from different stages. The prepared pure quartz samples were analyzed by ICP-MS. The analysis also shows different patterns of trace <span class="hlt">elements</span> according to the quartz stages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21156425','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21156425"><span id="translatedtitle">Removal of alkaline-<span class="hlt">earth</span> <span class="hlt">elements</span> by a carbonate precipitation in a chloride molten salt</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yung-Zun Cho; In-Tae Kim; Hee-Chui Yang; Hee-Chui Eun; Hwan-Seo Park; Eung-Ho Kim</p> <p>2007-07-01</p> <p>Separation of some alkaline-<span class="hlt">earth</span> chlorides (Sr, Ba) was investigated by using carbonate injection method in LiCl-KCl eutectic and LiCl molten salts. The effects of the injected molar ratio of carbonate([K{sub 2}(or Li{sub 2})CO{sub 3}/Sr(or Ba)Cl{sub 2}]) and the temperature(450-750 deg.) on the conversion ratio of the Sr or Ba carbonate were determined. In addition, the form of the Sr and Ba carbonate resulting from the carbonation reaction with carbonates was identified via XRD and SEM-EDS analysis. In these experiments, the carbonate injection method can remove Sr and Ba chlorides effectively over 99% in both LiCl-KCl eutectic and LiCl molten salt conditions. When Sr and Ba were co-presented in the eutectic molten salt, they were carbonated in a form of Ba{sub 0.5}Sr{sub 0.3}CO{sub 3}. And when Sr was present in LiCl molten salt, it was carbonated in the form of SrCO{sub 3}. Carbonation ratio increased with a decreasing temperature and it was more favorable in the case of a K{sub 2}CO{sub 3} injection than that of Li{sub 2}CO{sub 3}. Based on this experiment, it is postulated that carbonate precipitation method has the potential for removing alkali-<span class="hlt">earth</span> chlorides from LiCl-KCl eutectic and LiCl molten salts. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JAESc..43..207G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JAESc..43..207G"><span id="translatedtitle">Petrography and major <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Permo-Triassic sandstones, central India: Implications for provenance in an intracratonic pull-apart basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghosh, Sampa; Sarkar, Soumen; Ghosh, Parthasarathi</p> <p>2012-01-01</p> <p>Detrital mode, composition of feldspars and heavy minerals, and major <span class="hlt">element</span> chemistry of sandstones from the Permo-Triassic succession in the intracratonic Satpura Gondwana basin, central India have been used to investigate provenance. The Talchir Formation, the lowermost unit of the succession, comprises glacio-marine and glacio-fluvial deposits. The rest of the succession (base to top) comprising the Barakar, Motur, Bijori, Pachmarhi and Denwa formations, largely represent variety of fluvial depositional systems with minor fluvio-deltaic and fluvio-lacustrine sedimentation under a variety of climatic conditions including cold, warm, arid, sub-humid and semi-arid. QFL compositions of the sandstones indicate a predominantly continental block provenance and stable cratonic to fault-bounded basement uplift tectonic setting. Compositional maturity of sandstones gradually increases upwards from the Early Permian Talchir to the Middle Triassic Denwa but is punctuated by a sharp peak of increased maturity in the Barakar sandstones. This temporal change in maturity was primarily controlled by temporal variation in fault-induced basement uplift in the craton and was also influenced by climatic factors. Plots of different quartz types suggest plutonic source rocks for the Talchir sandstones and medium-to high-rank metamorphic plus plutonic source rocks for the younger sandstones. Composition of alkali feldspars in the Permo-Triassic sandstones and in different Precambrian rocks suggests sediment derivation from felsic igneous and metasedimentary rocks. Compositions of plagioclase in the Talchir and Bijori sandstones are comparable with those of granite, acid volcanic and metasedimentary rocks of the Precambrian basement suggesting the latter as possible source. Rare presence of high-K plagioclase in the Talchir sandstones, however, indicates minor contribution from volcanic source rock. Exclusively plagioclase-bearing metasedimentary rock, tonalite gneiss and mafic rocks are the probable sources of plagioclase in the Upper Denwa sandstones. Quartz-rich nature of the sandstones, predominance of K-feldspar over plagioclase and albite rich character of plagioclase in the sandstones is consistent with deposition in an intracratonic, pull-apart basin like the Satpura Gondwana basin. Composition of garnet and its comparison with that from the Precambrian basement rocks suggests mica-schist and amphibolite as possible sources. Predominance of dravite variety of tourmaline in the Permian sandstones suggests sediment supply from metasedimentary rocks. Presence of both dravite and schorl variety of tourmaline in subequal amount in the Triassic sandstones indicates sediment derivation from granitic and metasedimentary rocks. However, schorl-bearing rocks are absent in the basement complex of the study area. A-CN-K plot suggests granites, acid volcanic rock and meta-sediments of the basement as possible sources of the Talchir sandstones and metasedimentary rocks for the Barakar to Pachmarhi sandstones. The Denwa sandstones were possibly derived from K-feldspar-free, plagioclase-bearing metasediments, mafic rocks and tonalite gneiss. Chemical Index of Alteration (CIA) values suggest low intensity source rock weathering for the Talchir sandstones and higher intensity source rock weathering for the others. Various bivariate plots of major oxides composition of the sandstones suggest passive to active continental margin setting and even arc tectonic setting for a few samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAESc.113..980W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAESc.113..980W"><span id="translatedtitle">Mineralogy and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of the Co- and Cu-bearing sulfides from the Shilu Fe-Co-Cu ore district in Hainan Province of South China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zhilin; Xu, Deru; Zhang, Zhaochong; Zou, Fenghui; Wang, Li; Yu, Liangliang; Hu, Mingyue</p> <p>2015-12-01</p> <p>Hosted within the metamorphosed, neritic siliciclastic rocks and sedimentary carbonates of the Proterozoic Shilu Group, the Shilu Fe-Co-Cu ore district in Hainan Province of South China comprises the upper Fe- and the lower Co-Cu ore layers. Combined with the field observation, the mineralogical and geochemical studies of sulfides using electron microprobe and laser ablation ICP-MS analyses recognized three types of Co-Cu ores. Type I is represented by massive ores and mainly comprises the first generation of pyrite (PyI) which occurred either as recrystallized, subhedral to euhedral microcrystal aggregates (PyIa) or as elongated, fine-grained euhedral grains (PyIb) with an orientated alignment parallel to S1 foliation. Type II is banded, disseminated and brecciated ores, and composed of the second generation of pyrite (PyII) which displays internal rhythmic growth zoning, the first generations of chalcopyrite (CcpI) and pyrrhotite (PoI), and associated Co-(Ni)-(As)-sulfide minerals. Type III occurring as veins or veinlets mainly consists of the third generation of pyrite (PyIII) and the second generations of chalcopyrite (CcpII) and pyrrhotite (PoII), of which PyIII appears as subhedral to euhedrall grains or as rims of composite pyrite. The moderate Co and As, and high Ni contents as well as the low Co/Ni ratios (?2-5) in PyI indicate a sedimentary-metamorphic origin for Type I ores. The higher Co, Ni and As concentrations in PyIb relative to PyIa likely was related to an inhomogeneous deformation-metamorphism. The highest Co (av. 51,195 ppm) in PyII and Ni (av. 3374 ppm) in PoI most likely were linked to the preferred incorporation of Co into pyrite and Ni into pyrrhotite. Combined with the high Ag concentrations in CcpI (av. 266 ppm) and PyII (av. 13.32 ppm), the high Co/Ni ratios in PyII (av. 1241) suggest the derivation of Type II ores from a Co-Cu-Ni-Ag-rich hydrothermal fluid. Further, up to 9 wt.% Co concentrations in PyII show a temperature condition of 310-400 °C. In contrast, the depletion of trace <span class="hlt">elements</span> in CcpII and PyIII, and the lower Co/Ni ratios (av. 46) in PyIII suggest a Co-poor but Cu-bearing hydrothermal fluid for origin of Type III ores. The complex texture and chemical composition of sulfides combined with previous work confirm a four-stage metallogenesis for the Shilu Co-Cu ores. From early to late, these include: (1) the ca. 1075-880 Ma deposition of the primary Co-Cu ore source beds which most likely were derived from submarine, metalliferous hydrothermal fluids, (2) the syn-structural metamorphism which led to Type I ores due to the South China Caledonian Orogeny, (3) the first stage of hydrothermalism which produced Type II ores and most likely was associated with Indosinian magmatism, and (4) the second stage of hydrothermalism which yielded Type III ores and likely was related to Yanshanian magmatism. The first stage of hydrothermalism was considered to be significant for the Co-Cu enrichment. The Shilu Co-Cu ores thus are better attributed to a BIF origin, but greatly reworked and enriched by late structural deformation and hydrothermal activities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20152406','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20152406"><span id="translatedtitle">Determination of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in uranium-bearing materials by inductively coupled plasma mass spectrometry.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Varga, Zsolt; Katona, Róbert; Stefánka, Zsolt; Wallenius, Maria; Mayer, Klaus; Nicholl, Adrian</p> <p>2010-03-15</p> <p>A novel and simple analytical procedure has been developed for the trace-level determination of lanthanides (rare-<span class="hlt">earth</span> <span class="hlt">elements</span>) in uranium-bearing materials by inductively coupled plasma sector-field mass spectrometry (ICP-SFMS). The method involves a selective extraction chromatographic separation of lanthanides using TRU resin followed by ICP-SFMS analysis. The limits of detection of the method proposed is in the low pg g(-1) range, which are approximately two orders of magnitude better than that of without chemical separation. The method was validated by the measurement of reference material and applied for the analysis of uranium ore concentrates (yellow cakes) for nuclear forensic purposes, as a potential application of the methodology. PMID:20152406</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017278','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017278"><span id="translatedtitle">Laser-excited fluorescence of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in fluorite: Initial observations with a laser Raman microprobe</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Burruss, R.C.; Ging, T.G.; Eppinger, R.G.; Samson, a.M.</p> <p>1992-01-01</p> <p>Fluorescence emission spectra of three samples of fluorite containing 226-867 ppm total rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) were excited by visible and ultraviolet wavelength lines of an argon ion laser and recorded with a Raman microprobe spectrometer system. Narrow emission lines ( 0.9 for Eu2+ and 0.99 for Er3+. Detection limits for three micrometer spots are about 0.01 ppm Eu2+ and 0.07 ppm Er3+. These limits are less than chondrite abundance for Eu and Er, demonstrating the potential microprobe analytical applications of laser-excited fluorescence of REE in fluorite. However, application of this technique to common rock-forming minerals may be hampered by competition between fluorescence emission and radiationless energy transfer processes involving lattice phonons. ?? 1992.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017531','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017531"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> evidence for the petrogenesis of the banded series of the Stillwater Complex, Montana, and its anorthosites</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Loferski, P.J.; Arculus, R.J.; Czamanske, G.K.</p> <p>1994-01-01</p> <p>A rare <span class="hlt">earth</span> <span class="hlt">element</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6122378','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6122378"><span id="translatedtitle">Columbium-, rare-<span class="hlt">earth-element</span>-, and thorium-bearing veins near Salmon Bay, Southeastern Alaska. Open file report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Warner, J.D.</p> <p>1989-01-01</p> <p>In 1984 and 1985 the Bureau of Mines investigated radioactive carbonate veins near Salmon Bay, southeastern Alaska, for concentrations of columbium and associated metals. The veins cut units of graywacke, conglomerate, argillite, and limestone and range in width from less than an inch to greater than 10 ft and have a length ranging from less than a hundred to greater than 1,000 ft. Mineralogy of the veins is complex, and includes thorite, the rare-<span class="hlt">earth-element</span> minerals monazite, parisite, and bastnaesite, and a columbium mineral that is speculated to be columbite. Gangue minerals include ankerite, dolomite, siderite, quartz and albite. More than seventy veins were sampled but only three contain elevated metal concentrations along a significant strike length. These resources are small compared to columbium, REE, and thorium resources elsewhere in the world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23583939','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23583939"><span id="translatedtitle">Determination of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in dust deposited on tree leaves from Greater Cairo using inductively coupled plasma mass spectrometry.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shaltout, Abdallah A; Khoder, M I; El-Abssawy, A A; Hassan, S K; Borges, Daniel L G</p> <p>2013-07-01</p> <p>This work aims at monitoring the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and Th in dust deposited on tree leaves collected inside and outside Greater Cairo (GC), Egypt. Inductively coupled plasma mass spectrometry (ICP-MS) was employed. The concentration of REEs in the collected dust samples was found to be in the range from 1 to 60 ?g g(-1). The highest concentration of REEs was found in dust samples collected outside GC, in the middle of the Nile Delta. This would refer to the availability of black sands, due to desert wind occurrence during the sample collection, and anthropogenic activities. The limits of detection of the REEs ranged from 0.02 ng g(-1) for Tm to 3 ng g(-1) for Yb. There was an obvious variation in the concentration of REEs inside and outside GC due to variations of natural and anthropogenic sources. Strong correlations among all the REEs were found. PMID:23583939</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.V21D..05M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.V21D..05M"><span id="translatedtitle">Siderophile <span class="hlt">Element</span> Fractionation in the <span class="hlt">Earth</span>'s Core: Direct Estimate of Partition Coefficients from Primitive Siberian Flood Basalts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morgan, J. W.; Walker, R. J.</p> <p>2001-12-01</p> <p>Evidence from Os isotopes suggests that the siderophile <span class="hlt">element</span> signature in some deep-mantle plumes may be derived from the outer core. The siderophile <span class="hlt">element</span> pattern in the least fractionated plume basalts therefore may reflect solid-liquid metal fractionation, rather than that from partial melting of the upper mantle. Partition coefficients (D) derived from IIAB irons are governed by three major factors; <span class="hlt">element</span> melting point, atomic radius and electron configuration. Values for Au, Ni, Re and the heavy platinum group <span class="hlt">elements</span> (HPGE) plotted against melting point lie on a hyperbola with Os at the maximum. The light PGE (LPGE) also show a trend of increasing D with melting point but lie below the HPGE trend, perhaps due to differences in free atom electronic configuration. Siberian Flood Basalts (SFB) are of plume origin, and the Mokulaevsky and Morongovsky flows are the least crustally contaminated. Abundances of Ni, Rh, Pd, Ir, Pt and Au in these flows plot on a smooth curve against melting point when chondrite-normalized, but not when mantle-normalized. Thus, we explore the possibility that the SFB distributions reflect fractionation in the core rather than in the upper mantle. For 5.5 per cent crystallization, iron meteorite data yield much less fractionation of Ir than is seen in SFB, suggesting that D for Ir in the <span class="hlt">Earth</span>'s core is larger. Inversion of the SFB data yields a smooth curve when D values of PGE, Au and Ni are plotted against melting point. The D value for Ir is estimated to be about 5 times larger than in iron meteorites. If values for Re and Os are similarly enhanced, as suggested by high pressure experiments, Os isotopes in plumes may be more compatible with gradual formation of the inner core rather than early growth to the present size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7252282','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7252282"><span id="translatedtitle">Iridium, sulfur isotopes and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Cretaceous-Tertiary boundary clay at Stevns Klint, Denmark</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schmitz, B.; Andersson, P.; Dahl, J.</p> <p>1988-01-01</p> <p>Microbial activity and redox-controlled precipitation have been of major importance in the process of metal accumulation in the strongly Ir-enriched Cretaceous-Tertiary (K-T) boundary clay, the Fish Clay, at Stevns Klint in Denmark. Two important findings support this view: (1) Kerogen, recovered by leaching the Fish Clay in HCl and HF, shows an Ir concentration of 1100 ppb; this represents about 50% of the Ir present in the bulk sample Fish clay. Strong organometallic complexes is the most probable carrier phase for this fraction of Ir. Kerogen separated from the K-T boundary clay at Caravaca, Spain, similarly exhibits enhanced Ir concentrations. (2) Sulfur isotope analyses of metal-rich pyrite spherules, which occur in extreme abundance (about 10% by weight) in the basal Fish Clay, give a delta/sup 34/S value of -32 per thousand. This very low value shows that sulfide formation by anaerobic bacteria was intensive in the Fish Clay during early diagenesis. Since the pyrite spherules are major carriers of <span class="hlt">elements</span> such as Ni, Co, As, Sb and Zn, microbial activity may have played an important role for concentrating these <span class="hlt">elements</span>. In the Fish Clay large amounts of rare <span class="hlt">earth</span> <span class="hlt">elements</span> have precipitated from sea water on fish scales. Analyses reveal that, compared with sea water, the Fish Clay is only about four times less enriched in sea-water derived lanthanides than in Ir. This shows that a sea-water origin is plausible for <span class="hlt">elements</span> that are strongly enriched in the clay, but whose origin cannot be accounted for by a lithogenic precursor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988GeCoA..52..229S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988GeCoA..52..229S"><span id="translatedtitle">Iridium, sulfur isotopes and rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the Cretaceous-Tertiary boundary clay at Stevns Klint, Denmark</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmitz, Birger; Andersson, Per; Dahl, Jeremy</p> <p>1988-01-01</p> <p>Microbial activity and redox-controlled precipitation have been of major importance in the process of metal accumulation in the strongly Ir-enriched Cretaceous-Tertiary (K-T) boundary clay, the Fish Clay, at Stevns Klint in Denmark. Two important findings support this view: 1) Kerogen, recovered by leaching the Fish Clay in HCl and HF, shows an Ir concentration of 1100 ppb; this represents about 50% of the Ir present in the bulk sample Fish Clay. Strong organometallic complexes is the most probable carrier phase for this fraction of Ir. Kerogen separated from the K-T boundary clay at Caravaca, Spain, similarly exhibits enhanced Ir concentrations. 2) Sulfur isotope analyses of metal-rich pyrite spherules, which occur in extreme abundance (about 10% by weight) in the basal Fish Clay, give a ? 34S value of -32%.. This very low value shows that sulfide formation by anaerobic bacteria was intensive in the Fish Clay during early diagenesis. Since the pyrite spherules are major carriers of <span class="hlt">elements</span> such as Ni, Co, As, Sb and Zn, microbial activity may have played an important role for concentrating these <span class="hlt">elements</span>. In the Fish Clay large amounts of rare <span class="hlt">earth</span> <span class="hlt">elements</span> have precipitated from sea water on fish scales. Analyses reveal that, compared with sea water, the Fish Clay is only about four times less enriched in sea-water derived lanthanides than in Ir. This shows that a sea-water origin is plausible for <span class="hlt">elements</span> that are strongly enriched in the clay, but whose origin cannot be accounted for by a lithogenic precursor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/198144','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/198144"><span id="translatedtitle">Synthesis of mixed-ligand complexes of rare-<span class="hlt">earth</span> <span class="hlt">elements</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Panyushkin, V.T.; Akhrimenko, N.V.</p> <p>1994-09-10</p> <p>The authors have synthesized mixed-ligand complexes of Nd(III), Sm(III), Eu(III), Tb(III), Dy(III), Ho(III), Er(III), and Yb(III) with acetylacetone (I) and unsaturated organic acids (II): maleic, fumaric, acrylic, and methacrylic. According to <span class="hlt">elemental</span> analyses and thermogravimetric data the composition of Ln(I){sub 2}(II) {center_dot} 3H{sub 2}O does not depend on the basicity of the acid. The structure of compounds prepared was studied by IR, NMR, and luminescent spectroscopy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850057901&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Drare%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850057901&hterms=rare+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Drare%2Bearth"><span id="translatedtitle">Rare <span class="hlt">earth</span> and other <span class="hlt">elements</span> in components of the Abee enstatite chondrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Frazier, R. M.; Boynton, W. V.</p> <p>1985-01-01</p> <p>Radiochemical and instrumental neutron activation analyses of REEs and other <span class="hlt">elements</span> 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.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Litho.174..271C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Litho.174..271C"><span id="translatedtitle">The <span class="hlt">geochemistry</span> and petrogenesis of the Blue Draw Metagabbro</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ciborowski, T. Jake R.; Kerr, Andrew C.; McDonald, Iain; Ernst, Richard E.; Minifie, Matthew J.</p> <p>2013-08-01</p> <p>The Blue Draw Metagabbro (BDM) in western South Dakota, is an 800 m thick, layered intrusion, which is interpreted to have been intruded as a rift-related subvolcanic sill during the Palaeoproterozoic. The age and tectonic setting of the BDM are similar to those recorded by the East Bull Lake Suite of layered intrusions in Southern Ontario. These similarities have led previous authors to suggest that the two sets of intrusions are cogenetic. The East Bull Lake Suite intrusions are relatively well studied and are known to host significant contact-type Ni-Cu-PGE sulphide mineralisation, however, prior to this work, relatively little was known of BDM both in terms of its <span class="hlt">geochemistry</span> and mineralisation potential. Chemostratigraphic profiles through the BDM show that the intrusion is the product of at least two magma pulses which fractionated to produce a sequence of rocks which grade from peridotitic at the base of the intrusion to gabbronoritic at the upper margin. Closed-system fractionation following the intrusion of the second magma pulse caused the magma to become saturated in sulphur and precipitate Ni-Cu-PGE bearing sulphides-now preserved in a low-grade 50 m thick zone near the top of the intrusion. Petrological modelling shows that the parental melt of the BDM was a low-Ti tholeiite, with a trace <span class="hlt">element</span> chemistry defined by enrichments in large-ion lithophile and light rare-<span class="hlt">earth</span> <span class="hlt">elements</span> and prominent negative Nb, Ta, and Ti anomalies. This ‘arc-like' <span class="hlt">geochemistry</span> recorded by the BDM parent magma is shared with parent magmas of the East Bull Lake Suite and may suggest that the BDM and its potential Canadian relatives share a common magmatic source. However, the relative ubiquity of such geochemical signatures in Archaean-Palaeoproterozoic intracontinental magmatic rocks coeval with the BDM suggests that the geochemical similarities recorded by the BDM and East Bull Lake Suite are non-unique and hence, are not definitive evidence of a genetic link between the two sets of intrusions. Instead, this geochemical signature that is common to many ancient igneous provinces may indicate the presence of a transient and (currently) poorly understood Archaean-Palaeoproterozoic mantle reservoir which was a globally significant magma source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EurSS..48.1090V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EurSS..48.1090V"><span id="translatedtitle">Macro- and microelements including rare <span class="hlt">earth</span> <span class="hlt">elements</span> in some soils of the Sakhalin Island</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vodyanitskii, Yu. N.; Manakhov, D. V.; Savichev, A. T.</p> <p>2015-10-01</p> <p>Specific features of the chemical composition of burozems, podzols, and alluvial soils of the Sakhalin Island are revealed. Burozems on eluvial and colluvial deposits, podzols on marine sediments, and alluvial soils are enriched in Al and Ga and impoverished in Ca, P, and Sr. Burozems and alluvial soil contain more Fe than podzols. The gleyic burozem is very rich in chlorine. Podzols are depleted of Mn, Ni, Cu, and Zn, as well as of heavy lanthanide Y; they are rich in Ba, Sr, Na, K, and light lanthanides (La, Ce, Pr, Nd). The podzolization process affects the migration of manganese oxides as the carriers of lanthanides and Th and controls their distribution in the soil profiles. The alluvial soil is enriched in Na, K, Mg, and Zn; and it is depleted of Cu. The heavy lanthanide Y is included in other alluvium minerals than the light lanthanides (from La to Nd). The ash matter of the litter horizons is insignificantly enriched in Rb and Ni; the fir forest litter contains more Mg, Ca, Mn, S, and Zn than that under larch. In the larch-cedar forest growing on podzols, the litter poorly accumulates all the studied <span class="hlt">elements</span>, except for Ca, Mn, P, and S; the litter of sedge-reed grass association on the alluvial soil surface slightly accumulates all the studied <span class="hlt">elements</span>, except for Mn, P, and S.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=PETROLOGY&id=EJ371074','ERIC'); return false;" href="http://eric.ed.gov/?q=PETROLOGY&id=EJ371074"><span id="translatedtitle">Essential <span class="hlt">Elements</span> of Geologic Reports.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Webb, Elmer James</p> <p>1988-01-01</p> <p>Described is a report outline for geologic reports. Essential <span class="hlt">elements</span> include title; abstract; introduction; stratigraphy; petrography; <span class="hlt">geochemistry</span>; petrology; geophysics; structural geology; geologic history; modeling; economics; conclusions; and recommendations. (Author/CW)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010040','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010040"><span id="translatedtitle">Fractionation of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in allanite and monazite as related to geology of the Mt. Wheeler mine area, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lee, D.E.; Bastron, H.</p> <p>1967-01-01</p> <p>Rare-<span class="hlt">earth</span> contents of 20 allanites and 13 monazites, accessory minerals from a restricted outcrop area of intrusive granitic rocks, are reported. A quantity called sigma (??), which is the sum of the atomic percentages of La, Ce and Pr, is used as an index of composition with respect to the rare-<span class="hlt">earth</span> <span class="hlt">elements</span>. Values of sigma vary from 61.3 to 80.9 at.% for these allanites and monazites, representing an appreciable range of composition in terms of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span>. Degree of fractionation of rare <span class="hlt">earths</span> varies directly with CaO content of the granitic rocks, which in turn depends largely on proximity of limestone. Four xenoliths included in the study suggest that spotty mosaic equilibria are superimposed on the regional gradients and that locally the degree of fractionation of rare <span class="hlt">earths</span> responds to whole rock composition over distances of a few yards or less. The chemistry of the granitic rocks under study appears to be similar in some respects to that of alkalio rocks and carbonatites. Allanites from the most calcium-rich rocks show a pronounced concentration of the most basic rare <span class="hlt">earths</span>, and whole-rock concentrations of such rare constituents as total cerium <span class="hlt">earths</span>, Zr, F, Ti, Ba and Sr increase sympathetically with whole-rock calcium. The explanation for the concentration gradients observed in this chemical system must involve assimilation more than magmatic differentiation. ?? 1967.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAfES.102...50O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAfES.102...50O"><span id="translatedtitle">Mineralogical, chemical composition and distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in clay-rich sediments from Southeastern Nigeria</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Odoma, A. N.; Obaje, N. G.; Omada, J. I.; Idakwo, S. O.; Erbacher, J.</p> <p>2015-02-01</p> <p>Cretaceous claystone sediments from Enugu, Southeastern, Nigeria were analyzed for their mineralogy and chemistry. Major minerals are quartz and kaolinite while montmorillonite is in minor quantity. The sediments are silica-rich, but showed low values of Al, Fe, Sc and Cr. The values of the chemical index of alteration (CIA) ranged from 89.9 to 94.5 and the values of chemical index of weathering (CIW) ranged from 95.1 to 98.9. Low contents of the alkali and alkali <span class="hlt">earth</span> <span class="hlt">elements</span> (Na, K, Mg, Al, Ca) of the clay-rich sediments suggest a relatively more intense weathering of source area. Depleted Ba, Rb, Ca, and Mg suggest that they were probably flushed out by water during sedimentation. The mineralogical composition, REE contents, and <span class="hlt">elemental</span> ratios in the sediments suggest a provenance from mainly felsic rocks, with only minor contributions from basic sources. Despite intense weathering the REE, Th, and Sc remained in the clays suggesting that they were immobile.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21062425','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21062425"><span id="translatedtitle">Partitioning and Leaching Behavior of Actinides and Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in a Zirconolite- Bearing Hydrothermal Vein System</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Payne, Timothy E.; Hart, Kaye P.; Lumpkin, Gregory R.; McGlinn, Peter J.; Giere, Reto</p> <p>2007-07-01</p> <p>Chemical extraction techniques and scanning electron microscopy were used to study the distribution and behavior of actinides and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in hydrothermal veins at Adamello (Italy). The six samples discussed in this paper were from the phlogopite zone, which is one of the major vein zones. The samples were similar in their bulk chemical composition, mineralogy, and leaching behavior of major <span class="hlt">elements</span> (determined by extraction with 9 M HCl). However, there were major differences in the extractability of REE and actinides. The most significant influence on the leaching characteristics appears to be the amounts of U, Th and REE incorporated in resistant host phases (zirconolite and titanite) rather than readily leached phases (such as apatite). Uranium and Th are very highly enriched in zirconolite grains. Actinides were more readily leached from samples with a higher content of U and Th, relative to the amount of zirconium. The results show that REE and actinides present in chemically resistant host minerals can be retained under aggressive leaching conditions. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......329H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......329H"><span id="translatedtitle">Visible Light Driven Photoelectrodes Made of <span class="hlt">Earth</span> Abundant <span class="hlt">Elements</span> for Water Photoelectrolysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Qiang</p> <p></p> <p>With the aim of creating a clean and sustainable energy supply, the direct use of solar energy to produce chemical energy has been pursued for many years. Particularly, the photoelectrolysis of water to generate hydrogen by semiconductor photoelectrodes has attracted great attention because of its advantage of using only water and sunlight, both of which are widely distributed, as raw materials. The <span class="hlt">earth</span> abundant and visible light absorbing materials are promising for this application for the advantages of easy access and high theoretical solar to hydrogen conversion efficiency. In this thesis, the cadmium sulfide based and copper oxide based photoelectrodes were fabricated and characterized to determine their potential for photoelectrolysis. As one of the semiconductors with relatively narrow band gap, CdS (2.4eV) has a conduction band edge more negative than the water reduction potential level and a valence band edge more positive than the water oxidation potential level, enabling n-type CdS and p-type CdS as good candidates for photoanode and photocathode respectively. CdS thin film with thickness around 2mum was deposited onto Mo back contact on glass, which formed ohmic contact with CdS. The as-prepared CdS was intrinsic n-type due to the easy formation of sulfur vacancies and it was converted to p-type by the controlled thermal diffusion of copper atoms which substituted cadmium to produce acceptor state. The optimal Cu doping level for the interest of water photoelectrolysis was found to be at 5.4% concentration. Cu2O with band gap of 2.0eV is another attracting competitor for the photoelectrode among the metal-oxide semiconductors. Both thin film and highly aligned nanowire arrays Cu2O were prepared by thermal oxidation of Cu film and Cu nanowires on Au substrates synthesized by electrodeposition. Cu2O was found to be p-type because of the copper vacancies. The photocurrent of the Cu2O nanowires photocathode was found to be twice that of the Cu2O film, and the bare Cu2O photocathode suffered from a significant photo-induced reductive decomposition. By modifying the surface of the Cu2O nanowires with protecting layers of CuO and TiO2, direct contact of Cu2O with the electrolyte was avoided, and the Cu2O/CuO/TiO2 coaxial nanocable structures were found to gain 74% higher photocurrent and 4.5 times higher stability. Furthermore, the co-catalysts were also used to modify the photoelectrode surface to reduce the water splitting overpotentials by facilitating the transfer of the photo-induced carriers to the electrolyte. Cobalt based co-catalysts, both the Co2+ and Co3O4 thin film, enhanced the stability of the intrinsic n-CdS photoanode. The Pt modification of CdS:Cu, effectively eliminating the large transient photocurrent, enhanced the photocurrent and stability and positively shifted the onset potential of the cathodic photocurrent by 90 mV, and the hydrogen evolution from the p-type CdS:Cu/Pt photocathode was observed for the first time. This thesis not only studied the water photoelectrolysis potentials of CdS and Cu2O, but also presented general methods to prevent photocorrosion and enhance photo-activity, which could be also applied to other visible light responsive and <span class="hlt">earth</span> abundant materials to enlarge the range of material choice for solar water splitting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5927374','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5927374"><span id="translatedtitle">Separation of Bk(IV) and Ce(IV) from trivalent transplutonium and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> on ion exchangers in solutions of sulfuric acid</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guseva, L.I.; Stepushkina, V.V.</p> <p>1988-05-01</p> <p>The behavior of Am, Cm, Bk, Cf, Es, Ce, Eu, and Pr on anion exchangers and cation exchangers mixed with PbO/sub 2/ in solutions of sulfuric acid has been investigated. A significant difference between the distribution coefficients of Bk and Ce, on the one hand, and the remaining transplutonium <span class="hlt">elements</span> and rare-<span class="hlt">earth</span> <span class="hlt">elements</span>, on the other hand, which has been attributed to the oxidation of the first two <span class="hlt">elements</span> to the tetravalent state, has been discovered. Methods for the preconcentration and separation of Bk(IV) and Ce(IV) from the other transplutonium and rare-<span class="hlt">earth</span> <span class="hlt">element</span> son anion exchangers in 0.01-0.25 M H/sub 2/SO/sub 4/ solutions and on cation exchangers in 0.75-1.0 M H/sub 2/SO/sub 4/ solutions have been proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018457','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018457"><span id="translatedtitle">Comparison of the partitioning behaviours of yttrium, rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and titanium between hydrogenetic marine ferromanganese crusts and seawater</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bau, M.; Koschinsky, A.; Dulski, P.; Hein, J.R.</p> <p>1996-01-01</p> <p>In order to evaluate details of the partitioning behaviours of Y, rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), and Ti between inorganic metal oxide surfaces and seawater, we studied the distribution of these <span class="hlt">elements</span> in hydrogenetic marine ferromanganese (Fe-Mn) crusts from the Central Pacific Ocean. Nonphosphatized Fe-Mn crusts display shale-normalized rare <span class="hlt">earths</span> 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 <span class="hlt">element</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5098625','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5098625"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">element</span> patterns as correlation tools and tectonic indicators for the Paleogene Dillon Volcanics, southwestern Montana</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McDowell, R.J.; Fritz, W.J.; Ghazi, A.M. . Dept. of Geology)</p> <p>1993-04-01</p> <p>The Dillon Volcanics of the Paleogene Renova Formation consist of epiclastic, pyroclastic, and volcanic rocks. The latter are composed of alkaline and transitional basalts and rhyolites. Major and trace <span class="hlt">element</span> variation diagrams indicate that both rock types had a similar parent magma source, and that the rhyolites were mainly derived from a basaltic parent magma. This is confirmed by very similar rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns. The REE patterns are typical of continental rift zone volcanics, and indicate that bimodal rift zone volcanism occurred in a back-arc setting 30 m.y. before basin-and-range extension. Subsequent normal faulting, combined with Neogene erosion, has separated the dillon Volcanics into isolated outcrops that cannot be accurately correlated in the field. Major and trace <span class="hlt">element</span> compositional trends are not good correlation tools, but chondrite-normalized REE patterns are almost parallel for the rhyolites and can be used to correlate now-isolated outcrops. REE patterns for the basalts do not show the same degree of similarity, but their patterns do indicate a common magmatic source. REE patterns for continental rift settings typically show enrichment in light REE's, reflecting derivation from a light REE-enriched mantle source such as sub-continental lithosphere. As eruption of the Dillon volcanics was partly contemporaneous with arc volcanism related to the Laramide orogeny, the sub-continental lithosphere may have been enriched in light REE's bu subduction zone fluids derived from the down-going Farallon plate. However, it might not be possible to distinguish continental rift zone volcanics from continental back-arc basin volcanics. The authors favor the latter model because of the chronologic and geographic relationship of the dillon Volcanics with nearby continental arc volcanic fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007E%26PSL.260..361K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007E%26PSL.260..361K"><span id="translatedtitle">Contrasting behaviour of anthropogenic gadolinium and natural rare <span class="hlt">earth</span> <span class="hlt">elements</span> in estuaries and the gadolinium input into the North Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kulaks?z, Serkan; Bau, Michael</p> <p>2007-08-01</p> <p>All major rivers in northwestern Germany that flow into the North Sea, including the Weser River, display rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) patterns with large positive gadolinium (Gd) anomalies that indicate the presence of anthropogenic Gd derived from contrast agents used in magnetic resonance imaging. This microcontaminant cannot be removed by common sewage treatment technology and enters rivers and lakes with the discharge from waste water treatment plants. As elsewhere, a large fraction of the natural dissolved REE in the Weser River are associated with colloids. These colloids aggregate during mixing of freshwater and seawater in the low-salinity part of the Weser Estuary and the dissolved REE are partially removed from the river water together with the colloids. In marked contrast to the natural REE, the anthropogenic Gd behaves conservatively during this estuarine mixing and transits through the Weser Estuary almost unaffected. This indicates that the speciation of anthropogenic Gd is different from that of natural Gd and suggests a long environmental half-life of the anthropogenic Gd complexes used as contrast agents. The amount of anthropogenic Gd introduced into seawater via rivers is significant and produces anthropogenic positive Gd anomalies in coastal seawater. This is observed in the southwestern North Sea, off the coast of the East Frisian Islands, where anthropogenic Gd is mostly derived from the rivers Rhine and Thames. Its long environmental half-life and conservative estuarine behaviour suggest that anthropogenic Gd might be utilized as a pseudo-natural far-field tracer for truly dissolved riverine REE input into seawater and for discharge from waste water treatment plants and for sewage in river, ground and drinking water. The widespread distribution of anthropogenic Gd is an example of how the increasing use of "exotic" (ultra)trace <span class="hlt">elements</span> in high-tech processes will in the future significantly hamper studies of the distribution and geochemical behaviour of such <span class="hlt">elements</span> in natural systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://arxiv.org/pdf/0802.1810v1','EPRINT'); return false;" href="http://arxiv.org/pdf/0802.1810v1"><span id="translatedtitle">Structure and evolution of super-<span class="hlt">Earth</span> to super-Jupiter exoplanets: I. heavy <span class="hlt">element</span> enrichment in the interior</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>I. Baraffe; G. Chabrier; T. Barman</p> <p>2008-02-13</p> <p>We examine the uncertainties in current planetary models and we quantify their impact on the planet cooling histories and mass-radius relationships. These uncertainties include (i) the differences between the various equations of state used to characterize the heavy material thermodynamical properties, (ii) the distribution of heavy <span class="hlt">elements</span> within planetary interiors, (iii) their chemical composition and (iv) their thermal contribution to the planet evolution. Our models, which include a gaseous H/He envelope, are compared with models of solid, gasless <span class="hlt">Earth</span>-like planets in order to examine the impact of a gaseous envelope on the cooling and the resulting radius. We find that for a fraction of heavy material larger than 20% of the planet mass, the distribution of the heavy <span class="hlt">elements</span> in the planet's interior affects substantially the evolution and thus the radius at a given age. For planets with large core mass fractions ($\\simgr$ 50%), such as the Neptune-mass transiting planet GJ436b, the contribution of the gravitational and thermal energy from the core to the planet cooling history is not negligible, yielding a $\\sim$ 10% effect on the radius after 1 Gyr. We show that the present mass and radius determinations of the massive planet Hat-P-2b require at least 200 $\\mearth$ of heavy material in the interior, at the edge of what is currently predicted by the core-accretion model for planet formation. We show that if planets as massive as $\\sim$ 25 $\\mjup$ can form, as predicted by improved core-accretion models, deuterium is able to burn in the H/He layers above the core, even for core masses as large as $\\sim$ 100 $\\mearth$. We provide extensive grids of planetary evolution models from 10 $\\mearth$ to 10 M$_{\\rm Jup}$, with various fractions of heavy <span class="hlt">elements</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/576320','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/576320"><span id="translatedtitle">Trace and rare <span class="hlt">earth</span> <span class="hlt">elemental</span> variation in Arabian sea sediments through a transect across the oxygen minimum zone</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nath, B.N.; Rao, B.R.; Rao, C.M.; Bau, M.</p> <p>1997-06-01</p> <p>We have determined the calcium carbonate (CaCO{sub 3}), organic carbon (C{sub org}), trace <span class="hlt">element</span>, and rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) composition of surface sediments collected from a transect on the central western continental shelf and slope of India in the Eastern Arabian Sea. The transect samples across the oxygen minimum zone (OMZ) allows us to compare the relative abundances of trace <span class="hlt">elements</span> and REEs in the sediments beneath and beyond the OMZ. Shale-normalized REE patterns, La{sub n}/Yb{sub n} ratios, and Eu/Eu* anamolies indicate that the sediments in the study area are either derived from the adjoining Archaean land masses or from distal Indus source. Sediment deposited in the OMZ have high U values from 3.6 to 8.1 ppm, with their U{sub excess} (of that can be supplied by continental particles) values ranging between 82-91% of the total U, indicating that the U may be precipitated as U{sup +4} in the reducing conditions of OMZ. Sediments deposited beneath the intense OMZ (<0.2 mL/L) and away from the OMZ (1-2 mL/L) show slight negative Ce anomalies, with no significant differences between these two sets of sediments. The Ce/Ce*{sub shale} values are poorly related to U and C{sub org} which are indicators of suboxic bottom waters. Normative calculations suggest that two sources, namely, terrestrial and seawater (terrestrial > seawater) contribute to the total Ce anomaly of the sediments. The Ce anomaly values of the calculated seawater derived component are similar to the anomalies reported for other coastal waters and the oxygenated surface waters of the Arabian Sea and do not show any correspondence to the lowered redox state of the overlying water, probably due to the redirection of dissolved Ce into the oxic deeper water. 103 refs., 6 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15221192','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15221192"><span id="translatedtitle">Investigation of the separation of scandium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> from red mud by use of reversed-phase HPLC.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tsakanika, Lambrini V; Ochsenkühn-Petropoulou, Maria Th; Mendrinos, Leonidas N</p> <p>2004-07-01</p> <p>A chromatographic method has been developed for separation and determination of scandium (Sc) and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in samples from a red mud (RM)-utilization process. Reversed-phase high-performance liquid chromatography (RP-HPLC) with post-column derivatization using 4-(2-pyridylazo)-resorcinol (PAR) and UV-visible detection at 520 nm was tested using different gradient elution profiles and pH values to optimize separation and recovery, primarily for Sc but also for yttrium and the individual lanthanides, from iron present in the samples. The separation was performed in less than 20 min by use of a mobile phase gradient. The concentration of alpha-hydroxyisobutyric acid ( alpha-HIBA), as eluent, was altered from 0.06 to 0.4 mol L(-1) (pH 3.7) and 0.01 mol L(-1) sodium salt n-octane sulfonic acid (OS) was used as modifier. Very low detection limits in the nanogram range and a good resolution for Sc and REEs except for Y/Dy were achieved. Before application of the method to the red mud samples and to the corresponding bauxites, Sc and REEs were leached from red mud with 0.6 mol L(-1) HNO(3) and mostly separated, as a group, from the main <span class="hlt">elements</span> by ion exchange/selective elution (6 mol L(-1) HNO(3)) in accordance with a pilot-plant process developed in this laboratory. After evaporation of the eluent to dryness the extracted <span class="hlt">elements</span> were re-dissolved in the mobile phase. By use of this chromatographic method Sc, which is the most expensive of the <span class="hlt">elements</span> investigated and occurs in economically interesting concentrations in red mud, could be separated not only from co-existing Fe but also from Y/Dy, Yb, Er, Ho, Gd, Eu, Sm, Nd, Pr, Ce and La. All the <span class="hlt">elements</span> investigated were individually recovered. Their recoveries were found to be nearly quantitative. PMID:15221192</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26414924','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26414924"><span id="translatedtitle">The rare <span class="hlt">earth</span> <span class="hlt">elements</span> in municipal solid waste incinerators ash and promising tools for their prospecting.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Funari, Valerio; Bokhari, Syed Nadeem Hussain; Vigliotti, Luigi; Meisel, Thomas; Braga, Roberto</p> <p>2016-01-15</p> <p>Bottom and fly ashes from Municipal Solid Waste Incinerators (MSWI) are hazardous products that present concern for their safe management. An attractive option to reduce their impact both on the environment and the financial commitment is turning MSWI ashes into secondary raw materials. In this study we present the REE content and distribution of bottom and fly ashes from MSWI after a highly effective digestion method and samples analysis by ICP-MS. The chondrite-normalised REE patterns of MSWI bottom and fly ash are comparable with that of crustal averages, suggesting a main geogenic source. Deviations from typical crustal pattern (e.g., Eu, Tb) disclose a contribution of likely anthropogenic provenance. The correlation with major <span class="hlt">elements</span> indicates possible sources for REE and facilitates a preliminary resource assessment. Moreover, magnetic susceptibility measurements can be a useful prospecting method in urban ores made of MSWI ashes. The relationship between REE and some influencing parameters (e.g., Pricing Influence Factor) emphasises the importance of MSWI ash as alternative source of REE and the need of further efforts for REE recovery and purification from low concentrations but high flows waste. PMID:26414924</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830046860&hterms=Rock+Cycle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528Rock%2BCycle%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830046860&hterms=Rock+Cycle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528Rock%2BCycle%2529"><span id="translatedtitle">Rare <span class="hlt">earth</span> <span class="hlt">elements</span> in the sedimentary cycle - A pilot study of the first leg</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Basu, A.; Blanchard, D. P.; Brannon, J. C.</p> <p>1982-01-01</p> <p>The effects of source rock composition and climate on the natural abundances of rare <span class="hlt">elements</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30Q.573S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30Q.573S"><span id="translatedtitle">Chemical Exchange Between the Core and the Convecting Mantle of the <span class="hlt">Earth</span>: Evidence from Highly Siderophile <span class="hlt">Elements</span> (HSE)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmidt, G.; Palme, H.; Kratz, K. L.</p> <p>1995-09-01</p> <p>Core formation is a major physical and chemical event in the evolution of a differentiated planet. The core is the dominant repository of HSE in the <span class="hlt">Earth</span>. <span class="hlt">Element</span> ratios of HSE in peridotites provide insights into the accretion processes of the <span class="hlt">Earth</span> and the effect of core formation. Depletion of HSE in the <span class="hlt">Earth</span>'s mantle results from core formation. Refractory siderophile <span class="hlt">elements</span> are about a factor of > 100 depleted in the <span class="hlt">Earth</span>'s mantle compared to CI carbonaceous chondrites. Nevertheless, the concentrations of PGE, Re and Au (7.1 +/- 0.8 x 10^-3 CI chondrite abundances) are higher than would be expected from metal-silicate partitioning during core formation [1]. Several different explanations have been suggested to explain the low absolute abundances of these <span class="hlt">elements</span>. (1) Os, Re, Ir, Ru, Rh, Pd, Pt, and Au were added with a late chondritic veneer containing less than 1% of a CI component [2-9]. (2) Insufficient core formation, i.e. some metallic Fe-Ni was retained in the upper mantle during core formation [10]. (3) Disequilibrium during core formation; Segregation of metal from the upper mantle in later stages of accretion was so rapid that equilibrium was not attained [4,11,12]. (4) There was continuous formation of the core during accretion; Equilibrium between sinking metal grains and a molten magma ocean at high temperatures (3000-3500 K) [13]. (5) Increase in silicate/metal partition coefficients by pressure, temperature, or high f(O2) [5,14]; Solution of FeO in the core raises the f(O2) conditions at the core-mantle interface sufficiently to increase the equilibrium concentrations of the siderophile <span class="hlt">elements</span> in the mantle [15]. Studies of mantle-derived samples such as massif peridotites and peridotite xenoliths provide direct information on the nature and composition of the upper mantle. Massive peridotitic rocks from Zabargad island (Red Sea), Lanzo (Italy), Ronda (Spain) and peridotitic xenoliths from Mongolia were analysed for Os, Re, Ir, Ru, Rh, Pd, and Au with a slightly modified neutron activation analysis in combination with a NiS extraction method [16]. All samples (except peridotitic xenoliths) have essentially unfractionated patterns (except Pd/Ir) despite significant variations in absolute abundances [17]. Os/Re ratios from massive peridotitic rocks from Zabargad are chondritic. Peridotitic xenoliths generally have Os/Re-ratios much higher than the chondritic ratio [2]. The Pd/Ir ratios from all studied peridotites are approximately two times and the Rh/Ir ratios are approximately 1.5 times higher than the chondritic ratio of 1.21 and 0.29, respectively. This is in qualitative agreement with estimates of Pd and Ir in primitive undepleted mantle [1]. The non-chondritic Pd/Ir and Rh/Ir ratios is either the result of Pd and Rh addition or these <span class="hlt">elements</span> are not quantitatively removed from the mantle in the process of core formation [10]. Extrapolation of experimentally determined palladium and iridium metal/silicate partition coefficients to 3500 K are 3.8x10^3 and 2x10^8, respectively [18,19]. The observed non-chondritic ratio of Ir to Pd in the upper mantle is in qualitative agreement with experimentally determined metal/silicate partition coefficients for Ir and Pd. This could support recent speculation on the possibility of chemical exchange between the outer liquid shell of the core and the convecting mantle of the <span class="hlt">Earth</span>. Acknowledgements. This work was supported by DFG. References: [1] Morgan J. W. (1986) JGR, 91, 12375-12387. [2] Morgan J. W. et al. (1981) Tectonophys., 75, 47-67. [3] Anders E. (1968) Acc. Chem. Res., 1, 289-298. [4] Turekian K. K. and Clark S. P. (1969) EPSL, 6, 346-348. [5] Kimura K. et al. (1974) GCA, 38, 683-701. [6] Ganapathy R. and Anders E. (1974) Proc. LPSC. [7] Chou C.-L. (1978) Proc. LPSC 9th, 219-230. [8] Jagoutz E. et al. (1979) Proc. LPSC 10th, 2031-2050. [9] Wanke H. (1981) Philos. Trans. R. Soc. London, A303, 287-302. [10] Jones J. H. and Drake M. J. (1986) Nature, 322, 221-228. [11] Ringwood A. E. (1966) GCA, 30, 41-104. [12] Morgan J. W. and Lovering J. F.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740012357','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740012357"><span id="translatedtitle">Trace <span class="hlt">geochemistry</span> of lunar material</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morrison, G. H.</p> <p>1974-01-01</p> <p>The lunar samples from the Apollo 16 and 17 flights which were analyzed include soil, igneous rock, anorthositic gabbro, orange soil, subfloor basalt, and norite breccia. Up to 57 <span class="hlt">elements</span> including majors, minors, rare <span class="hlt">earths</span> and other trace <span class="hlt">elements</span> were determined in the lunar samples. The analytical techniques used were spark source mass spectrometry and neutron activation analysis. The latter was done either instrumentally or with group radiochemical separations. The differences in abundances of the <span class="hlt">elements</span> in lunar soils at the various sites are discussed. With regard to the major <span class="hlt">elements</span> only Si is about the same at all the sites. A detailed analysis which was performed on a sample of the Allende meteorite is summarized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/sir/2010/5220/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/sir/2010/5220/"><span id="translatedtitle">The principal rare <span class="hlt">earth</span> <span class="hlt">elements</span> deposits of the United States-A summary of domestic deposits and a global perspective</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Long, Keith R.; Van Gosen, Bradley S.; Foley, Nora K.; Cordier, Daniel</p> <p>2010-01-01</p> <p>The rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) are fifteen <span class="hlt">elements</span> with atomic numbers 57 through 71, from lanthanum to lutetium ('lanthanides'), plus yttrium (39), which is chemically similar to the lanthanide <span class="hlt">elements</span> and thus typically included with the rare <span class="hlt">earth</span> <span class="hlt">elements</span>. Although industrial demand for these <span class="hlt">elements</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23625586','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23625586"><span id="translatedtitle">Polymer monolithic capillary microextraction combined on-line with inductively coupled plasma MS for the determination of trace rare <span class="hlt">earth</span> <span class="hlt">elements</span> in biological samples.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Lin; Chen, Beibei; He, Man; Hu, Bin</p> <p>2013-07-01</p> <p>A rapid and sensitive method based on polymer monolithic capillary microextraction combined on-line with microconcentric nebulization inductively coupled plasma MS has been developed for the determination of trace/ultratrace rare <span class="hlt">earth</span> <span class="hlt">elements</span> in biological samples. For this purpose, the iminodiacetic acid modified poly(glycidyl methacrylate-trimethylolpropane trimethacrylate) monolithic capillary was prepared and characterized by SEM and FTIR spectroscopy. Factors affecting the extraction efficiency, such as sample pH, sample flow rate, sample/eluent volume, and coexisting ions were investigated in detail. Under the optimal conditions, the LODs for rare <span class="hlt">earth</span> <span class="hlt">elements</span> were in the range of 0.08 (Er) to 0.97 ng/L (Nd) with a sampling frequency of 8.5 h(-1), and the RSDs were between 1.5% (Sm) and 7.4% (Nd) (c = 20 ng/L, n = 7). The proposed method was successfully applied to the analysis of trace/ultratrace rare <span class="hlt">earth</span> <span class="hlt">elements</span> in human urine and serum samples, and the recoveries for the spiked samples were in the range of 82-105%. The developed method was simple, rapid, sensitive, and favorable for the analysis of trace/ultratrace rare <span class="hlt">earth</span> <span class="hlt">elements</span> in biological samples with limited sample volume. PMID:23625586</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5492567','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5492567"><span id="translatedtitle">Determination of Barium and selected rare-<span class="hlt">earth</span> <span class="hlt">elements</span> in geological materials employing a HpGe detector by radioisotope excited x-ray fluorescence</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>LaBrecque, J.J.; Preiss, I.L.</p> <p>1984-01-01</p> <p>The laterite material (geological) from Cerro Impacto was first studied by air radiometric techniques in the 1970's and was found to have an abnormally high radioactive background. Further studies showed this deposit to be rich in thorium, columbium, barium and rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (mostly La, Ce, Pr and Nd). A similar work has been reported for the analysis of Brazil's lateritic material from Morro do Ferro to determine <span class="hlt">elemental</span> compositions (including barium and rare-<span class="hlt">earth</span> <span class="hlt">elements</span>) and its relationship to the mobilization of thorium from the deposit using a Co-57 radioisotope source. The objective of this work was to develop an analytical method to determine barium and rare-<span class="hlt">earth</span> <span class="hlt">element</span> present in Venezuelan lateritic material from Cerro Impacto. We have employed a method before, employing a Si(Li) detector, but due to the low detection efficiencies in the rare-<span class="hlt">earth</span> K-lines region (about 30 KeV - 40 KeV), we have decided to study the improvement in sensitivities and detection limits using an hyperpure germanium detector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715501H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715501H"><span id="translatedtitle">Geochemical and mineralogical constraints on the distribution and enrichment of the rare <span class="hlt">earth</span> <span class="hlt">elements</span> during pedogenesis and tropical weathering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hardy, Liam; Smith, Martin; Moles, Norman; Marsellos, Antonios</p> <p>2015-04-01</p> <p>Current European manufacturing relies heavily on imports from the USA & China for unprocessed rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) and rare <span class="hlt">earth</span> oxides (REOs). It has been suggested that the EU holds viable reserves of REEs that, with adequate research, could satisfy 10% of EU industrial demand, by the recycling of mine waste from bauxite production (red muds) alone (Deady, E. (BGS), 2014). Focus has been turned to the potential for Mount Weld type laterite deposits being exploited in the EU, but limited exploration and understanding of EU laterite (& paleo laterite) formations currently makes them unattractive to investment. Although previously researched, the full range of factors influencing the transition of rare <span class="hlt">earth</span> (primarily lanthanide series, Y & Sc) <span class="hlt">elements</span> between mineral and clay phases in allochthonous soils, saprolites and laterites is not fully understood, especially in present and Paleo-European environments (Herrington, Boni, Skarpelis, & Large, 2007) (Deady, E. (BGS), 2014) but several deposits globally are suggested to have formed at economically viable concentrations due to this secondary remobilisation & transition from mineral to clay phase and subsequent seasonal leaching and evaporation system, to form depositional buffer zones other than the soil base. (Hoatson, Jaireth, & Miezitis, 2011) (Berger, Janots, Gnos, Frei, & Bernier, 2014). This project intends to use new techniques in sequential extractions, ICP-MS, Quantitative XRD & SEM analysis to expand current knowledge around lateritic & allochtonous ore forming, & weathering processes. Heavy REE content and mineralogical variations in clays will be examined, with examples from a selection of profiles across Southern Europe (and potentially paleo soils from Scandinavia) to define the main influencing factors on REE concentration. Are the specific sites enriched simply by the nature of their source rock (protolith), by the soil formation (pedogenesis), or by biogenic & meteorological factors? These results will then be applied in targeted, environmentally focused exploration projects, and perhaps enhance techniques used industrially for the extraction of HREEs, for less environmentally damaging production in sensitive areas (with current research sites within national parks in Italy and Portugal; and in areas where it is believed more attention should be paid to environmental preservation, including Central Turkey and Southern China). It is hypothesised that: HREE content in tropical laterite formations is due primarily to the source rock's mineralogy, although it's distribution is a result of slower genesis and leaching as opposed to more common biogenetic pedogenesis. It is suggested this distribution initially forms banded horizontal enrichment zones according to protolith, but eventual separation of heavy and light REEs is controlled by clay-surface (the protolith's weathering style), solvent type, fluctuation and availability. It may be found, as in Fe-Ni laterite resources globally (Herrington, Boni, Skarpelis, & Large, 2007) (Eliopoulos, 2000), that high initial bedrock concentrations of REEs are not necessarily required if prolonged weathering continues to concentrate these <span class="hlt">elements</span>/minerals over longer periods (although this has been found inversely in certain Turkish bauxites (Karadag?, Peli, Ary, & Ayhan, 2008)). Regardless of eventual concentrations, identifying the argillic phase and the time scales required for clay REE hosting clay formation may broaden the European search for supergene enrichments to REE hosting marine shales, mineral sands and other sedimentary formations that have been long-term- weathered without major displacement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.V31C2337O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.V31C2337O"><span id="translatedtitle"><span class="hlt">Geochemistry</span> and Minerality of Wine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oze, C.; Horton, T. W.; Beaman, M.</p> <p>2010-12-01</p> <p>Kaolinite (Al2Si2O5(OH)4) and gibbsite (Al(OH)3) are capable of forming in a variety of environments including anthropogenic solutions such as wine. Here, we evaluate the <span class="hlt">geochemistry</span> of twelve white wines in order to assess the potential relationship between kaolinite/gibbsite saturation and minerality, a common wine descriptor used to express the rock and/or soil character in the aromas and flavors of wines. Aluminum and Si concentrations ranged from 228-1,281 µg L-1 and 6,583-19,746 µg L-1, respectively, where Si and Al are the only <span class="hlt">elements</span> to demonstrate positive covariance with minerality scores. Sulfur levels varied from 25,013-167,383 µg L-1 and show the strongest negative covariance with minerality scores. However, like all of the <span class="hlt">elements</span> studied (Al, Si, Na, Mg, S, K, Ca, and Fe), these trends were not significantly different than random at the 95% confidence level. In contrast, the relative degrees of gibbsite/kaolinite saturation display strong positive covariance with minerality scores and these trends are not random at the greater than 95% confidence level. Overall, our tasters were able to accurately assess the degree of gibbsite/kaolinite saturation amongst the twelve wines based on the objective of assessing minerality. Although the wines were undersaturated with respect to gibbsite/kaolinite, geochemical modeling reveals that increasing the wines’ pHs from ~3.3 to 4.1-4.6 (which is achievable on the palate where saliva has a pH of 7.4) results in gibbsite/kaolinite oversaturation. By considering that minerality is a function of gibbsite/kaolinite saturation and decreasing S, the origin of minerality’s taste and chemical origin in wine with known physical standards becomes increasingly crystalline.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003423','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003423"><span id="translatedtitle">Effect of Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (Er, Ho) on Semi-Metallic Materials (ScN) in an Applied Electric Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kim, Hyunjung; Park, Yeonjoon; King, Glen C.; Lee, Kunik; Choi, Sang H.</p> <p>2012-01-01</p> <p>The development of materials and fabrication technology for field-controlled spectrally active optics is essential for applications such as membrane optics, filters for LIDARs, windows for sensors, telescopes, spectroscopes, cameras and flat-panel displays. The dopants of rare <span class="hlt">earth</span> <span class="hlt">elements</span>, in a host of optical systems, create a number of absorption and emission band structures and can easily be incorporated into many high quality crystalline and amorphous hosts. In wide band-gap semiconductors like ScN, the existing deep levels can capture or emit the mobile charges, and can be ionized with the loss or capture of the carriers which are the fundamental basis of concept for smart optic materials. The band gap shrinkage or splitting with dopants supports the possibility of this concept. In the present work, a semi-metallic material (ScN) was doped with rare <span class="hlt">earth</span> <span class="hlt">elements</span> (Er, Ho) and tested under an applied electric field to characterize spectral and refractive index shifts by either Stark or Zeeman Effect. These effects can be verified using the UV-Vis spectroscopy, the Hall Effect measurement and the ellipsometric spectroscopy. The optical band gaps of ScN doped with Er and doped with Ho were experimentally estimated as 2.33eV and 2.24eV ( 0.2eV) respectively. This is less than that of undoped ScN (2.5 0.2eV). The red-shifted absorption onset is a direct evidence for the decrease of band gap energy (Eg), and the broadening of valence band states is attributable to the doping cases. A decrease in refractive index with an applied field was observed as a small shift in absorption coefficient using a variable angle spectroscopic ellipsometer. In the presence of an electric field, mobile carriers are redistributed within the space charge region (SCR) to produce this electro-refractive effect. The shift in refractive index is also affected by the density and location of deep potential wells within the SCR. In addition, the microstructure change was observed by a TEM analysis. These results give an insight for future applications for the field-controlled spectrally active material systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMDI31A2208S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMDI31A2208S"><span id="translatedtitle">TerraFERMA: The Transparent Finite <span class="hlt">Element</span> Rapid Model Assembler for multi-physics problems in the solid <span class="hlt">Earth</span> sciences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spiegelman, M. W.; Wilson, C. R.; Van Keken, P. E.</p> <p>2013-12-01</p> <p>We announce the release of a new software infrastructure, TerraFERMA, the Transparent Finite <span class="hlt">Element</span> Rapid Model Assembler for the exploration and solution of coupled multi-physics problems. The design of TerraFERMA is driven by two overarching computational needs in <span class="hlt">Earth</span> sciences. The first is the need for increased flexibility in both problem description and solution strategies for coupled problems where small changes in model assumptions can often lead to dramatic changes in physical behavior. The second is the need for software and models that are more transparent so that results can be verified, reproduced and modified in a manner such that the best ideas in computation and <span class="hlt">earth</span> science can be more easily shared and reused. TerraFERMA leverages three advanced open-source libraries for scientific computation that provide high level problem description (FEniCS), composable solvers for coupled multi-physics problems (PETSc) and a science neutral options handling system (SPuD) that allows the hierarchical management of all model options. TerraFERMA integrates these libraries into an easier to use interface that organizes the scientific and computational choices required in a model into a single options file, from which a custom compiled application is generated and run. Because all models share the same infrastructure, models become more reusable and reproducible. TerraFERMA inherits much of its functionality from the underlying libraries. It currently solves partial differential equations (PDE) using finite <span class="hlt">element</span> methods on simplicial meshes of triangles (2D) and tetrahedra (3D). The software is particularly well suited for non-linear problems with complex coupling between components. We demonstrate the design and utility of TerraFERMA through examples of thermal convection and magma dynamics. TerraFERMA has been tested successfully against over 45 benchmark problems from 7 publications in incompressible and compressible convection, magmatic solitary waves and Stokes flow with free surfaces. We have been using it extensively for research in basic magma dynamics, fluid flow in subduction zones and reactive cracking in poro-elastic materials. TerraFERMA is open-source and available as a git repository at bitbucket.org/tferma/tferma and through CIG. Instability of a 1-D magmatic solitary wave to spherical 3D waves calculated using TerraFERMA</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5628091','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5628091"><span id="translatedtitle">Trends in organic <span class="hlt">geochemistry</span> for petroleum exploration</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tissot, B.P.</p> <p>1988-08-01</p> <p>Exploration efficiency has increased since 1970 due to improvements in geophysical treatments and the development of organic <span class="hlt">geochemistry</span>. Further increase of the success ratio in wildcats is expected during the 1990s from integrating all <span class="hlt">earth</span> sciences in basin modeling. Explorationists expect from <span class="hlt">geochemistry</span> a clear answer to several questions essential for prospect evaluation: existence and location of source rock kitchens, amount and type of hydrocarbons generated, migration paths, and quantity and type of petroleum accumulated in traps. Based on the scientific knowledge developed during the last 20 years, such a clear answer can now be given to all questions related to generation. Kinetic models of oil generation will help us quantify the evaluation. Regarding migration, both approaches - observations and basin model - offer promising trends for individual trap evaluation. However, further work is needed before a quantitative figure of inplace reserves can be given. Examples of bacterial and thermal gas prospects in the Po basin (northern Italy), mainly from lower Tertiary and lower Mesozoic sources, respectively, are presented. Occurrences of liquid oil at great depth in the same basin are also presented, and the influences of kerogen type, burial history, geothermal gradient, and pressure regime are discussed. Immature heavy oils are present in the Adriatic basin and in Sicily. Their conditions of generation are interpreted with respect to specific type of high-sulfur crudes and burial history. More generally the important role of a late subsidence associated with the Europe-Africa collision is emphasized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/sir/2008/5224/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/sir/2008/5224/"><span id="translatedtitle">Statistical Analysis of Major Ion and Trace <span class="hlt">Element</span> <span class="hlt">Geochemistry</span> of Water, 1986-2006, at Seven Wells Transecting the Freshwater/Saline-Water Interface of the Edwards Aquifer, San Antonio, Texas</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mahler, Barbara J.</p> <p>2008-01-01</p> <p>This report by the U.S. Geological Survey, in cooperation with the San Antonio Water System, describes the results of a statistical analysis of major ion and trace <span class="hlt">element</span> <span class="hlt">geochemistry</span> of water at seven wells transecting the freshwater/saline-water interface of the Edwards aquifer in San Antonio, Texas, either over time or in response to variations in hydrologic conditions. The data used in this report were collected during 1986-2006. The seven monitoring wells are screened at different depths in the aquifer at three sites that form a generally north-to-south transect. The three wells of the southern site and the deeper of the two middle-site wells are open to the freshwater/saline-water transition zone, which contains saline water. The shallower well of the middle site and the two wells of the northern site are open to the freshwater zone. Mean specific conductance (SC) values were greater at transition-zone wells than at freshwater-zone wells, but SC did not vary systematically with depth. Concentrations of all major ions except bicarbonate were greater at transition-zone wells than at freshwater-zone wells, but concentrations tended to be more variable at freshwater-zone wells. Mean molar ratios of magnesium:calcium, sulfate:chloride, and sodium:chloride were similar at transition-zone wells and freshwater-zone wells. Concentrations of trace <span class="hlt">elements</span> for many water samples at the seven transect wells were below the laboratory analytical reporting level. Detections of trace <span class="hlt">elements</span> were more frequent at transition-zone wells, and mean concentrations of cadmium, chromium, copper, lead, and silver were elevated at transition-zone wells relative to freshwater-zone wells. All strong correlations between SC and major ions were positive, and in general there were more and stronger correlations between SC and major ions in the water from the freshwater-zone wells than from the transition-zone wells. Except for the shallowest transition-zone well, the transition-zone wells had relatively few strong correlations overall. The lack of a strong correlation indicates that much of the variability in the major ion concentrations at these wells might be a result of analytical variability caused by the multiple laboratory analytical methods used. In most cases, strong correlations between concentrations of trace <span class="hlt">elements</span> were positive, and transition-zone wells and freshwater-zone wells had water with a similar number of significant correlations. Principal components analysis indicates dilution of ground water by low-ionic-strength meteoric water at the three freshwater-zone wells and at the shallowest transition-zone well. At the two deeper transition-zone wells at the southern site, principal components analysis indicates that there is no systematic variation in major ion concentrations. At three transition-zone wells, there was a general trend toward less salinity over the 21-year period of sampling. Trends in SC at the freshwater-zone wells were less consistent. There is no systematic change in the direction of trend in SC by water type (saline or fresh), between sites, or with depth. In general, trends in major ion concentrations corresponded to those in SC. For each trace <span class="hlt">element</span> over the 21-year sampling period, there was either no trend or a downward trend. Relations between SC, major ions, and major ion molar ratios and hydrologic indicators (concurrent or prior time-averaged measures of water level and effective rainfall) were investigated. Correlations between geochemical variables and measures of water level in the freshwater-zone wells were much more frequent than correlations between geochemical variables and measures of water level in the transition-zone wells. There were correlations between SC and all measures of water level at the two freshwater-zone wells at the northern site, but there were no correlations between SC and any measures of water level at any transition-zone wells. SC was correlated with effe</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20171311','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20171311"><span id="translatedtitle">Comparison of single and sequential extraction procedures for the study of rare <span class="hlt">earth</span> <span class="hlt">elements</span> remobilisation in different types of soils.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rao, Chebrolu Rama Mohan; Sahuquillo, Angels; Lopez-Sanchez, Jose Fermin</p> <p>2010-03-10</p> <p>With the continual increase in the utilisation of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) for industrial and agricultural purposes, research into the environmental and biogeochemical behaviour of REE had attracted much interest in recent times. This study principally describes the distribution of REE in four different types of soils like lateritic soil (S-1), in situ natural soil (S-2), soil contaminated by mining activity (S-3) and accidentally polluted soil (S-4) utilizing the optimised BCR sequential extraction procedure and partial extractions with various types of single extractants such as unbuffered salt solutions 0.1 M NaNO(3), 0.01 M CaCl(2), 1 M NH(4)NO(3); complexing agents 0.005 M DTPA and 0.05 M EDTA; acid solutions 0.43 M CH(3)COOH and 1 M HCl. Comparison of the sum of the four BCR fractions, which included an aqua regia attack on the residue, with the pseudo-total aqua regia digest values to assess the accuracy of the BCR partioning approach has been undertaken. Partial extraction results with several single extractants have also been reported for all the REE <span class="hlt">elements</span> including yttrium which have been analysed by the optimised BCR procedure. Results obtained after 24 h extraction with each of the single extractant have also been discussed. The extraction with 1 M HCl during 24 h yielded similar quantities of REE as those released under the combined steps of 1, 2 and 3 of the BCR sequential extraction for all the four different type of soil samples indicating that this reagent can be used successfully to estimate the total extractable contents of REE in various types of soil samples. PMID:20171311</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP23E3633B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP23E3633B"><span id="translatedtitle">Critical Zone Weathering and Your Smartphone: Understanding How Mineral Decomposition and Colloid Redistribution Can Generate Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Deposits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bern, C.; Foley, N.</p> <p>2014-12-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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. <span class="hlt">Elemental</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010QSRv...29..265G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010QSRv...29..265G"><span id="translatedtitle">A major glacial-interglacial change in aeolian dust composition inferred from Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in Antarctic ice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabrielli, Paolo; Wegner, Anna; Petit, Jean Robert; Delmonte, Barbara; De Deckker, Patrick; Gaspari, Vania; Fischer, Hubertus; Ruth, Urs; Kriews, Michael; Boutron, Claude; Cescon, Paolo; Barbante, Carlo</p> <p>2010-01-01</p> <p>We present the first Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REE) concentration record determined in 294 sections of an Antarctic ice core (EPICA Dome C), covering a period from 2.9 to 33.7 kyr BP. REE allow a detailed quantitative evaluation of aeolian dust composition because of the large number of variables (i.e. 14 <span class="hlt">elements</span>). REE concentrations match the particulate dust concentration profile over this period and show a homogeneous crustal-like composition during the last glacial stage (LGS), with only a slight enrichment in medium REE. This signature is consistent with the persistent fallout of a mixture of dust from heterogeneous sources located in different areas or within the same region (e.g. South America). Starting at ˜15 kyr BP, there was a major change in dust composition, the variable character of which persisted throughout the Holocene. This varying signature may highlight the alternation of single dust contributions from different sources during the Holocene. We observe that the frequent changes in REE composition at the onset of the Holocene (10-13.5 kyr BP) are linked to dust size and in turn to wind strength and/or the path of the atmospheric trajectory. This may indicate that atmospheric circulation dictated the composition of the dust fallout to East Antarctica at that time. Although the dust concentrations remained fairly low, a notable return towards more glacial dust characteristics is recorded between 7.5 and 8.3 kyr BP. This happened concomitantly with a widespread cold event around 8 kyr BP that was 400-600 years long and suggests a moderate reactivation of the dust emission from the same potential source areas of the LGS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Ap.....58..512M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Ap.....58..512M"><span id="translatedtitle">Investigation of Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> in the Atmosphere of the roAp Star HD 134214: Nd II, Nd III, and Gd II Lines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mykhailytskaya, N. G.</p> <p>2015-12-01</p> <p>High-resolution spectra are used to investigate the abundance of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in the atmosphere of the magnetic, rapidly oscillating, chemically peculiar (roAp) star HD134214. The neodymium abundance is investigated using the lines of neodymium in the first and second ionization states. Disruption of ionization equilibrium REE (mismatch of the contents determined according to the lines of singly and doubly ionized atoms) is found in the atmosphere of the roAp star. Excess abundance of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (relative to the Sun) is found. The results of an abundance analysis of REE and some other <span class="hlt">elements</span> are presented. The modulus and the components Br /Bm of the magnetic field are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5354490','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5354490"><span id="translatedtitle">Separation of Bk(IV) and Ce(IV) from trivalent transplutonium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> on ion exchange resins in solutions of sulfuric acid</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guseva, L.I.; Stepushkina, V.V.</p> <p>1987-11-01</p> <p>Th behavior of Am, Cm, Bk, Cf, Es, Ce, Eu, and Pr on an anion exchange resin and a cation exchange resin in a mixture with PbO/sub 2/ was investigated in sulfuric acid solutions. A substantial difference was detected in the distribution coefficients of Bk and Ce, on the one hand, and the remaining transplutonium and rare <span class="hlt">earth</span> <span class="hlt">elements</span>, on the other, associated with oxidation of the first two <span class="hlt">elements</span> to the tetravalent state. Methods are proposed for the concentration and separation of Bk(IV) and Ce(IV) from the other transplutonium and rare <span class="hlt">earth</span> <span class="hlt">elements</span> on an anion exchange resin in solution of 0.01-0.25 M H/sub 2/SO/sub 4/ and a cation exchange resin in 0.75-1.0 M H/sub 2/SO/sub 4/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Ap....tmp...62M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Ap....tmp...62M"><span id="translatedtitle">Investigation of Rare-<span class="hlt">Earth</span> <span class="hlt">Elements</span> in the Atmosphere of the roAp Star HD 134214: Nd II, Nd III, and Gd II Lines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mykhailytskaya, N. G.</p> <p>2015-11-01</p> <p>High-resolution spectra are used to investigate the abundance of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REE) in the atmosphere of the magnetic, rapidly oscillating, chemically peculiar (roAp) star HD134214. The neodymium abundance is investigated using the lines of neodymium in the first and second ionization states. Disruption of ionization equilibrium REE (mismatch of the contents determined according to the lines of singly and doubly ionized atoms) is found in the atmosphere of the roAp star. Excess abundance of the rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (relative to the Sun) is found. The results of an abundance analysis of REE and some other <span class="hlt">elements</span> are presented. The modulus and the components Br /Bm of the magnetic field are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Tectp.483..413B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Tectp.483..413B"><span id="translatedtitle">Comment on "<span class="hlt">Geochemistry</span>, petrogenesis and tectonic setting of the Samothraki mafic suite, NE Greece: Trace-<span class="hlt">element</span>, isotopic and zircon age constraints" by N. Koglin, D. Kostopoulos & T. Reischmann [Tectonophysics 473, 53-68 (doi:10.1016/j.tecto.2008.10.028)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bonev, Nikolay; Stampfli, Gérard</p> <p>2010-03-01</p> <p>The work by Koglin et al. (Koglin, N., Kostopoulos, D., Reichmann, T., 2009. <span class="hlt">Geochemistry</span>, petrogenesis and tectonic setting of the Samothraki mafic suite, NE Greece: Trace-<span class="hlt">element</span>, isotopic and zircon age constraints. Tectonophysics 473, 53-68. doi:10.1016/j.tecto.2008.10.028), where the authors have proposed to nullify the scenario presented by Bonev and Stampfli (Bonev, N., Stampfli, G., 2008. Petrology, <span class="hlt">geochemistry</span> and geodynamic implications of Jurassic island arc magmatism as revealed by mafic volcanic rocks in the Mesozoic low-grade sequence, eastern Rhodope, Bulgaria. Lithos 100, 210-233) is here put under discussion. The arguments for this proposal are reviewed in the light of available stratigraphic and radiometric age constraints, geochemical signature and tectonics of highly relevant Jurassic ophiolitic suites occurring immediately north of the Samothraki mafic suite. Our conclusion is that the weak arguments and the lack of knowledge on the relevant constraints from the regional geologic information make inconsistent the proposal and the model of these authors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18970723','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18970723"><span id="translatedtitle">Subcellular distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> and characterization of their binding species in a newly discovered hyperaccumulator Pronephrium simplex.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lai, Ying; Wang, Qiuquan; Yang, Limin; Huang, Benli</p> <p>2006-08-15</p> <p>Subcellular distribution of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs, including 14 lanthanides and yttrium) in a newly discovered REE hyperaccumulator, Pronephrium simplex (P. simplex), was determined by a chemical sequence extraction followed by ICP-MS analysis. Results showed that most REEs are associated with cell wall and proteins, and REEs concentration in the proteins, 2899.5mugg(-1), is much higher than those in the cell wall; in the chloroplast of P. simplex, REEs distribute almost equally in chloroplast membrane and thylakoid, while most REEs in the thylakoid are binding with photosystem II (PS II); a new REE-binding peptide in the lamina of P. simplex, which can accumulate REEs up to 3000mugg(-1) and has higher affinity with light REEs, was characterized, indicating that its molecular mass is 5073Da, and may have beta-sheet structure; isoelectrofocusing electrophoretic photograph indicated that it is acidic peptide with IP of 3.7. Such information should be useful for understanding of both the storage and physiological role of REEs in P. simplex and further studies on the phytoremediation of REEs contaminated environments. PMID:18970723</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15228111','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15228111"><span id="translatedtitle">Cyanex 923 as the extractant in a rare <span class="hlt">earth</span> <span class="hlt">element</span> impurity analysis of high-purity cerium oxide.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Duan, Taicheng; Li, Hongfei; Kang, JianZhen; Chen, Hangting</p> <p>2004-06-01</p> <p>In this work, the feasibility of employing Cyanex 923 as an extractant into the non-cerium REE (rare <span class="hlt">earth</span> <span class="hlt">elements</span>) impurity analysis of high-purity cerium oxide was investigated. Through investigations on the choice of the extraction medium, the optimium extraction acidity, matrix Ce4+ effect on the non-cerium REE ion extraction, the optimium extractant concentration and suitable extracting time, and oscillation strengh, it was found that when the phase ratio was at 1:1 and the acicidity was about 2% H2SO4, by gently shaking by hand for about 2 min, 10 mL of 30% Cyanex 923 could not extract even for a 20 ng amount of non-cerium REE3+ ions. However, the extraction efficiency for Ce4+ of 100 mg total amount under the same conditions was about 96%, indicating that a 25-fold preconcentration factor could be achieved. Thus, it was concluded that Cyanex 923 could be used in a REE impurity analysis of 99.9999% or so pure cerium oxide for primary sepapation to elimilate matrix-induced interferences encountered in an ICP-MS (inductively coupled plasma mass spectroscopy) determination. PMID:15228111</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22314612','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22314612"><span id="translatedtitle">Magnetocaloric effect in heavy rare-<span class="hlt">earth</span> <span class="hlt">elements</span> doped Fe-based bulk metallic glasses with tunable Curie temperature</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Li, Jiawei; Huo, Juntao; Chang, Chuntao E-mail: dujun@nimte.ac.cn; Du, Juan E-mail: dujun@nimte.ac.cn; Man, Qikui; Wang, Xinmin; Li, Run-Wei; Law, Jiayan</p> <p>2014-08-14</p> <p>The effects of heavy rare <span class="hlt">earth</span> (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE?=?Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE <span class="hlt">element</span> and its concentration can easily tune T{sub C} in a large temperature range of 120?K without significantly decreasing the magnetic entropy change (?S{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ?S{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{sub C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4451788','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4451788"><span id="translatedtitle">Formation of carbonatite-related giant rare-<span class="hlt">earth-element</span> deposits by the recycling of marine sediments</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hou, Zengqian; Liu, Yan; Tian, Shihong; Yang, Zhiming; Xie, Yuling</p> <p>2015-01-01</p> <p>Carbonatite-associated rare-<span class="hlt">earth-element</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4572474','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4572474"><span id="translatedtitle">Some Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> Analysis by Microwave Plasma Torch Coupled with the Linear Ion Trap Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xiong, Xiaohong; Jiang, Tao; Qi, Wenhao; Zuo, Jun; Yang, Meiling; Fei, Qiang; Xiao, Saijin; Yu, Aimin; Zhu, Zhiqiang; Chen, Huanwen</p> <p>2015-01-01</p> <p>A sensitive mass spectrometric analysis method based on the microwave plasma technique is developed for the fast detection of trace rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in aqueous solution. The plasma was produced from a microwave plasma torch (MPT) under atmospheric pressure and was used as ambient ion source of a linear ion trap mass spectrometer (LTQ). Water samples were directly pneumatically nebulized to flow into the plasma through the central tube of MPT. For some REEs, the generated composite ions were detected in both positive and negative ion modes and further characterized in tandem mass spectrometry. Under the optimized conditions, the limit of detection (LOD) was at the level 0.1?ng/mL using MS2 procedure in negative mode. A single REE analysis can be completed within 2~3 minutes with the relative standard deviation ranging between 2.4% and 21.2% (six repeated measurements) for the 5 experimental runs. Moreover, the recovery rates of these REEs are between the range of 97.6%–122.1%. Two real samples have also been analyzed, including well and orange juice. These experimental data demonstrated that this method is a useful tool for the field analysis of REEs in water and can be used as an alternative supplement of ICP-MS. PMID:26421013</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.B41D0325H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.B41D0325H"><span id="translatedtitle">Rare <span class="hlt">Earth</span> <span class="hlt">Element</span> Signatures of Early Diagenesis in Pore Waters at Methane-Seeps from Hydrate Ridge, off Oregon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Himmler, T.; Haley, B.; Torres, M. E.; Klinkhammer, G. P.; Bohrmann, G.; Peckmann, J.</p> <p>2010-12-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations of pore waters from Beggiatoa covered sediments at methane-seeps on southern Hydrate Ridge were analyzed using ion-exchange chromatography. Pore water REE concentration significantly increase within the first 2 cm below seafloor compared to bottom water concentration. Below 2 cm a gradual decrease is observed, reaching bottom water REE concentrations at 5 cm. At this depth, pore water sulfate is completely consumed and converted to hydrogen-sulfide through sulfate reduction. Shale-normalized REE patterns show a linear light REE-depletion across the REE series. At 2 cm a distinct convex-shaped, light REE-depleted pattern with a positive cerium (Ce) anomaly is observed. All other samples reveal negative Ce anomalies. These findings suggest (1) an active REE-source immediately below the sediment-water interface, which might be related to the anaerobic oxidation of methane coupled to sulfate reduction at this depth (c.f. Boetius et al., 2000. A marine consortium apparently mediating anaerobic oxidation of methane. Nature 407, 623-626), and (2) REE-removal from pore waters probably caused by the uptake of REEs in authigenic minerals (e.g. carbonates, sulfides, barite).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRC..118..592G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRC..118..592G"><span id="translatedtitle">From the subtropics to the central equatorial Pacific Ocean: Neodymium isotopic composition and rare <span class="hlt">earth</span> <span class="hlt">element</span> concentration variations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grenier, MéLanie; Jeandel, Catherine; Lacan, FrançOis; Vance, Derek; Venchiarutti, CéLia; Cros, Alexandre; Cravatte, Sophie</p> <p>2013-02-01</p> <p>Neodymium isotopic compositions (?Nd) and rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) concentrations were measured for filtered surface to deep waters (112 samples) in the Southern Tropical Pacific. The relatively detailed picture of these tracer distributions allowed us to refine the areas where oceanic ?Nd variations occur. ?Nd values increase for most of the water masses flowing from Samoa to the Solomon Sea and in the Papua New Guinea (PNG) area, as already observed. Furthermore, water masses arriving from the eastern equatorial Pacific (200-550 m depth) also revealed radiogenic values, possibly acquired in the vicinity of the South American coasts and Galapagos Islands. These ?Nd variations affect the whole water column. The most likely process causing such variations is "boundary exchange" between the numerous radiogenic slopes/margins located in this area and seawater flowing past. Dissolution of atmospheric deposition and/or diffuse streaming of volcanic ash are also suggested to explain the radiogenic ?Nd observed at the surface in the PNG area. Interestingly, a positive europium (Eu) anomaly characterizes the normalized REE patterns of most of the studied water masses. This anomaly is consistent with the REE patterns of sediment and rock samples that are potential sources for the local waters. Such consistency reinforces the hypothesis that lithogenic sources play a major role in the oceanic REE budget, thanks to "boundary exchange." The data set presented here is a good basis for further sampling that will be realized in the framework of the ongoing GEOTRACES program (www.geotraces.org).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26035414','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26035414"><span id="translatedtitle">Formation of carbonatite-related giant rare-<span class="hlt">earth-element</span> deposits by the recycling of marine sediments.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hou, Zengqian; Liu, Yan; Tian, Shihong; Yang, Zhiming; Xie, Yuling</p> <p>2015-01-01</p> <p>Carbonatite-associated rare-<span class="hlt">earth-element</span> (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 (87)Sr/(86)Sr 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.geology.wisc.edu/people/sahaiPDF/Sahai2007.pdf','EPRINT'); return false;" href="http://www.geology.wisc.edu/people/sahaiPDF/Sahai2007.pdf"><span id="translatedtitle">WHAT IS MEDICAL MINERALOGY AND <span class="hlt">GEOCHEMISTRY</span>?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Sahai, Nita</p> <p></p> <p>WHAT IS MEDICAL MINERALOGY AND <span class="hlt">GEOCHEMISTRY</span>? The connection between human health of medical mineralogy and <span class="hlt">geochemistry</span> (MMG) focuses on understanding the equilibria and reaction pathways phases with naturally occurring, inorganic solid phases within the human body. Medical mineralogy</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17203370','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17203370"><span id="translatedtitle"><span class="hlt">Geochemistry</span> of the barkinite liptobiolith (Late Permian) from the Jinshan Mine, Anhui Province, China.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Yuzhuang; Lin, Mingyue; Qin, Peng; Zhao, Cunliang; Jin, Kankun</p> <p>2007-02-01</p> <p>This paper discusses the <span class="hlt">geochemistry</span> and mineralogy of the barkinite liptobiolith of the Late Permian age from the Jinshan Mine, Guangde County, Anhui Province, China. Samples were examined using inductively coupled plasma-mass spectroscopy, X-ray fluorescence, cold-vapor atomic absorption spectrometry, ion-selective electrode, sequential chemical extraction, scanning electron microscopy equipped with energy-dispersive X-ray, and optical microscopy. The coal is a medium-ash and high-sulfur resource. Minerals in the coal are composed of kaolinite, pyrite, calcite, and quartz. Pyrite and calcite are derived from seawater during peat accumulation. Quartz in the coal is of authigenic origin. Part of the kaolinite is from a land-source region, and part occurs as cell-fillings and is of authigenic origin. The results also indicate that the barkinite liptobiolith contains some toxic <span class="hlt">elements</span> in high concentrations. <span class="hlt">Elements</span> including Li, Be, Si, Sc, Ti, V, Cr, Fe, Ga, Se, Y, Zr, Mo, the rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs), W, Hg, Tl, Pb, Th, and U in the coals are enriched in the barkinite liptobiolith. Results of sequential chemical extraction showed that Li, Sc, Ti, Cr, Y, Zr, REEs, and Th in the coal mainly occur as silicates, while Be and W are related to organic matter. Pyrite is the dominant source of S, Mo, Hg, Tl, and Pb. Gallium only occurs in silicate, and U and V occur both in organic and silicate associations. PMID:17203370</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/ofr20131072','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/ofr20131072"><span id="translatedtitle">Preliminary estimates of the quantities of rare-<span class="hlt">earth</span> <span class="hlt">elements</span> contained in selected products and in imports of semimanufactured products to the United States, 2010</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bleiwas, Donald I.; Gambogi, Joseph</p> <p>2013-01-01</p> <p>Rare-<span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) are contained in a wide range of products of economic and strategic importance to the Nation. The REEs may or may not represent a significant component of that product by mass, value, or volume; however, in many cases, the embedded REEs are critical for the device’s function. Domestic sources of primary supply and the manufacturing facilities to produce products are inadequate to meet U.S. requirements; therefore, a significant percentage of the supply of REEs and the products that contain them are imported to the United States. In 2011, mines in China produced roughly 97 percent of the world’s supply of REEs, and the country’s production of these <span class="hlt">elements</span> will likely dominate global supply until at least 2020. Preliminary estimates of the types and amount of rare-<span class="hlt">earth</span> <span class="hlt">elements</span>, reported as oxides, in semimanufactured form and the amounts used for electric vehicle batteries, catalytic converters, computers, and other applications were developed to provide a perspective on the Nation’s use of these <span class="hlt">elements</span>. The amount of rare-<span class="hlt">earth</span> metals recovered from recycling, remanufacturing, and reuse is negligible when the tonnage of products that contain REEs deposited in landfills and retained in storage is considered. Under favorable market conditions, the recovery of REEs from obsolete products could potentially displace a portion of the supply from primary sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011E%26PSL.311..253C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011E%26PSL.311..253C"><span id="translatedtitle">Highly siderophile <span class="hlt">element</span> systematics of the 3.3 Ga Weltevreden komatiites, South Africa: Implications for early <span class="hlt">Earth</span> history</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Connolly, Brian D.; Puchtel, Igor S.; Walker, Richard J.; Arevalo, Ricardo; Piccoli, Philip M.; Byerly, Gary; Robin-Popieul, Christophe; Arndt, Nick</p> <p>2011-11-01</p> <p>Highly siderophile <span class="hlt">element</span> (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundances, Re-Os isotopic systematics, and major-, minor-, and lithophile trace <span class="hlt">element</span> abundances are determined for a suite of remarkably fresh komatiites from the Weltevreden Formation (Fm.) of the Barberton Greenstone Belt, South Africa. The komatiite lavas examined are calculated to have contained ca. 31% MgO upon emplacement, and are among the most MgO-rich lavas ever erupted onto <span class="hlt">Earth</span>'s surface. Based on the partitioning behavior of V, indicating reduced conditions of magma formation, as well as the low calculated H 2O abundance of ~ 0.02% in the mantle source, anhydrous melting for the Weltevreden Fm. komatiites is inferred. The high calculated liquidus temperatures of the emplaced komatiite lavas of ca. 1600 °C require an unusually hot (~ 1800 °C) mantle source, > 100 °C hotter than the ambient contemporaneous mantle. These observations are most consistent with formation of the Weltevreden komatiites via deep (~ 530 km) melting in a mantle plume. The Re-Os isotopic data for twelve whole-rock samples and an olivine separate define a precise Re-Os isochron age of 3266 ± 8 Ma (2? mean) and an initial 187Os/ 188Os of 0.10440 ± 5 (? 187Os = - 0.13 ± 0.05). The Re-Os data, coupled with the relatively high calculated HSE abundances in the mantle source totaling ~ 80% of those in modern Primitive Mantle (PM) estimates, indicate that at least some portions of the deep, early Archean mantle evolved with essentially chondritic Re/Os and absolute HSE abundances that are typical of the sources of late Archean komatiites. If the HSE budget of the terrestrial mantle was established via late accretion of several large planetesimals following the cessation of major chemical interaction between the core and the mantle, our data indicate that by 3.3 Ga, these materials were well homogenized within the mantle domains sampled by the Weltevreden komatiites and, by inference, within the mantle as a whole.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26062469','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26062469"><span id="translatedtitle">Laboratory calibration and field testing of the Chemcatcher-Metal for trace levels of rare <span class="hlt">earth</span> <span class="hlt">elements</span> in estuarine waters.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Petersen, Jördis; Pröfrock, Daniel; Paschke, Albrecht; Broekaert, Jose A C; Prange, Andreas</p> <p>2015-10-01</p> <p>Little knowledge is available about water concentrations of rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in the marine environment. The direct measurement of REEs in coastal waters is a challenging task due to their ultra-low concentrations as well as the high salt content in the water samples. To quantify these <span class="hlt">elements</span> at environmental concentrations (pg L(-1) to low ng L(-1)) in coastal waters, current analytical techniques are generally expensive and time consuming, and require complex chemical preconcentration procedures. Therefore, an integrative passive sampler was tested as a more economic alternative sampling approach for REE analysis. We used a Chemcatcher-Metal passive sampler consisting of a 3M Empore Chelating Disk as the receiving phase, as well as a cellulose acetate membrane as the diffusion-limiting layer. The effect of water turbulence and temperature on the uptake rates of REEs was analyzed during 14-day calibration experiments by a flow-through exposure tank system. The sampling rates were in the range of 0.42 mL h(-1) (13 °C; 0.25 m s(-1)) to 4.01 mL h(-1) (13 °C; 1 m s(-1)). Similar results were obtained for the different REEs under investigation. The water turbulence was the most important influence on uptake. The uptake rates were appropriate to ascertain time-weighted average concentrations of REEs during a field experiment in the Elbe Estuary near Cuxhaven Harbor (exposure time 4 weeks). REE concentrations were determined to be in the range 0.2 to 13.8 ng L(-1), where the highest concentrations were found for neodymium and samarium. In comparison, most of the spot samples measured along the Chemcatcher samples had REE concentrations below the limit of detection, in particular due to necessary dilution to minimize the analytical problems that arise with the high salt content in marine water samples. This study was among the first efforts to measure REE levels in the field using a passive sampling approach. Our results suggest that passive samplers could be an effective tool to monitor ultra-trace concentrations of REEs in coastal waters with high salt content. PMID:26062469</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V41A2761S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V41A2761S"><span id="translatedtitle">Methodology Measuring Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> in High TDS Reservoir Brines Application as Natural Tracers in CCUS Studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, W.; Mcling, T. L.; Smith, R. W.; Neupane, H.</p> <p>2013-12-01</p> <p>In recent years rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REE) have been demonstrated to be useful natural tracers for geochemical processes in aqueous environments. The application of REE's to carbon dioxide utilization and storage (CCUS) could provide researchers with a sensitive, inexpensive tool for tracking the movement of CO2 and displaced formation brines. By definition, geologic reservoirs that have been deemed suitable for carbon capture and storage contain formation brine with total dissolved solids (TDS) greater than 10,000 ppm and often these formation brines exceed 75,000 ppm TDS. This high TDS water makes it very difficult to measure REE, which typically occur at part per trillion concentrations. Critical to the use of REE for CCUS studies is the development of a procedure, which allows for the pre-concentration of REE's across a wide range of water quality. Additionally, due to the large number of samples that will need analysis, any developed procedure must be inexpensive, reproducible, and quick to implement. As part of the Big Sky Carbon Sequestration Project the INL's Center for Advance Energy Studies is developing REE pre-concentration procedures based on methods reported in the literature. While there are many REE pre-concentration procedures in the literature, our tests have shown these methods have difficulty at TDS greater than seawater (roughly 35,000 ppm TDS). Therefore, the ability to quantitatively measure REE's in formation brines with very high TDS has required the modification of an already developed procedure. After careful consideration and testing we selected methods modified after those described by Kingston et al., 1978 and Strachan et al., 1989 utilizing chelating media for very high TDS waters and ion-exchange media as detailed by Crock et al., 1984; Robinson et al., 1985; and Stetzenbach et al., 1994 for low TDS (<10,000 ppm TDS) waters. These modified procedures have been successfully tested in our laboratory and have proven effective in greatly reducing interfering monovalent and divalent cation concentrations (e.g. Ba) and enriching the REE up to 100X for analysis. The procedures are straightforward, inexpensive, and require little infrastructure, using only single chromatography columns with inexpensive, reusable, commercially available resins and wash chemicals. The procedures have been tested with synthetic brines and waters (up to 250,000 ppm TDS) and field water samples (up to 5,000 ppm TDS). Testing has produced data with REE capture efficiency exceeding 95%, while reducing interfering <span class="hlt">elements</span> by more than 93%. Further method development and testing continues in preparation for brine analysis of waters from the Big Sky Carbon Sequestration Partnership's Kevin Dome Pilot Study and the University of Wyoming's Carbon Institutes Rock Springs Uplift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26076480','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26076480"><span id="translatedtitle">Uptake and Effects of Six Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REEs) on Selected Native and Crop Species Growing in Contaminated Soils.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carpenter, David; Boutin, Céline; Allison, Jane E; Parsons, Jessica L; Ellis, Deanna M</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/2008/1356/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2008/1356/"><span id="translatedtitle">Factors that Influence the Price of Al, Cd, Co, Cu, Fe, Ni, Pb, Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span>, and Zn</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Papp, John F.; Bray, E. Lee; Edelstein, Daniel L.; Fenton, Michael D.; Guberman, David E.; Hedrick, James B.; Jorgenson, John D.; Kuck, Peter H.; Shedd, Kim B.; Tolcin, Amy C.</p> <p>2008-01-01</p> <p>This report is based on a presentation delivered at The 12th International Battery Materials Recycling Seminar, March 17-20, 2008, Fort Lauderdale, Fla., about the factors that influence prices for aluminum, cadmium, cobalt, copper, iron, lead, nickel, rare <span class="hlt">earth</span> <span class="hlt">elements</span>, and zinc. These are a diverse group of metals that are of interest to the battery recycling industry. Because the U.S. Geological Survey (USGS) closely monitors, yet neither buys nor sells, metal commodities, it is an unbiased source of metal price information and analysis. The authors used information about these and other metals collected and published by the USGS (U.S. production, trade, stocks, and prices and world production) and internationally (consumption and stocks by country) from industry organizations, because metal markets are influenced by activities and events over the entire globe. Long-term prices in this report, represented by unit values, were adjusted to 1998 constant dollars to remove the effects of inflation. A previous USGS study in this subject area was 'Economic Drivers of Mineral Supply' by Lorie A. Wagner, Daniel E. Sullivan, and John L. Sznopek (USGS Open File Report 02-335). By seeking a common cause for common behavior of prices among the various metal commodities, the authors found that major factors that influence prices of metal commodities were international events such as wars and recessions, and national events such as the dissolution of the Soviet Union in 1991 and economic growth in China, which started its open door policy in the 1970s but did not have significant market impact until the 1990s. Metal commodity prices also responded to commodity-specific events such as tariff or usage changes or mine strikes. It is shown that the prices of aluminum, cadmium, copper, iron, lead, nickel, and zinc are at historic highs, that world stocks are at (or near) historic lows, and that China's consumption of these metals had increased substantially, making it the world's leading consumer of these metals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP31B..08D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP31B..08D"><span id="translatedtitle">Geophysical expression of a buried niobium and rare <span class="hlt">earth</span> <span class="hlt">element</span> deposit: the Elk Creek carbonatite, Nebraska, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drenth, B.; Phillips, J. D.; Kass, A.; Krahenbuhl, R. A.</p> <p>2014-12-01</p> <p>The lower Paleozoic Elk Creek carbonatite is a 6-8 kilometer diameter intrusive complex buried under 200 meters of sedimentary rocks in southeastern Nebraska. It hosts the largest known niobium deposit in the U.S. and a rare <span class="hlt">earth</span> <span class="hlt">element</span> (REE) deposit. The carbonatite is composed of several lithologies, the relations of which are poorly understood. Niobium mineralization is most enriched within a magnetite beforsite unit, and REE oxides are concentrated in a barite beforsite unit. The carbonatite intrudes Proterozoic country rocks. A high-resolution airborne gravity gradient and magnetic survey was flown over the carbonatite in 2012. The carbonatite is associated with an annular vertical gravity gradient high with a subdued central low, and a central magnetic high surrounded by magnetic field values lower than those over the country rocks. Geophysical, borehole, and physical property data are combined for an interpretation of these signatures. The carbonatite is denser than the country rocks, explaining the gravity gradient high. Most carbonatite lithologies have weaker magnetic susceptibilities than those of the country rocks, explaining why the carbonatite produces a magnetic low at its margin. The primary source of the central magnetic high is interpreted to be mafic rocks that are strongly magnetized and are present in large volumes. Magnetite beforsite is very dense (mean density 3200 kg/m3) and strongly magnetized (median 0.073 SI magnetic susceptibility), producing a gravity gradient high and contributing to the aeromagnetic high. Barite beforsite has physical properties similar to most of the carbonatite volume, making it a poor geophysical target. Geophysical anomalies indicate the presence of dense and strongly magnetized rocks at depths below existing boreholes, either a large volume of magnetite beforsite or another unknown lithology. Studies are underway to investigate possible effects of alteration and magnetic remanence, and to better constrain the 3D distribution of magnetite beforsite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4468158','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4468158"><span id="translatedtitle">Uptake and Effects of Six Rare <span class="hlt">Earth</span> <span class="hlt">Elements</span> (REEs) on Selected Native and Crop Species Growing in Contaminated Soils</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Carpenter, David; Boutin, Céline; Allison, Jane E.; Parsons, Jessica L.; Ellis, Deanna M.</p> <p>2015-01-01</p> <p>Rare <span class="hlt">earth</span> <span class="hlt">elements</span> (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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.127..171M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.127..171M"><span id="translatedtitle">South Pacific dissolved Nd isotope compositions and rare <span class="hlt">earth</span> <span class="hlt">element</span> distributions: Water mass mixing versus biogeochemical cycling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Molina-Kescher, Mario; Frank, Martin; Hathorne, Ed</p> <p>2014-02-01</p> <p>Despite its enormous extent and importance for global climate, the South Pacific has been poorly investigated in comparison to other regions with respect to chemical oceanography. Here we present the first detailed analysis of dissolved radiogenic Nd isotopes (?Nd) and rare <span class="hlt">earth</span> <span class="hlt">elements</span> (REEs) in intermediate and deep waters of the mid-latitude (˜40°S) South Pacific along a meridional transect between South America and New Zealand. The goal of our study is to gain better insight into the distribution and mixing of water masses in the South Pacific and to evaluate the validity of Nd isotopes as a water mass tracer in this remote region of the ocean. The results demonstrate that biogeochemical cycling (scavenging processes in the Eastern Equatorial Pacific) and release of LREEs from the sediment clearly influence the distribution of the dissolved REE concentrations at certain locations. Nevertheless, the Nd isotope signatures clearly trace water masses including AAIW (Antarctic Intermediate Water) (average ?Nd = -8.2 ± 0.3), LCDW (Lower Circumpolar Deep Water) (average ?Nd = -8.3 ± 0.3), NPDW (North Pacific Deep Water) (average ?Nd = -5.9 ± 0.3), and the remnants of NADW (North Atlantic Deep Water) (average ?Nd = -9.7 ± 0.3). Filtered water samples taken from the sediment-water interface under the deep western boundary current off New Zealand suggest that boundary exchange processes are limited at this location and highlight the spatial and temporal variability of this process. These data will serve as a basis for the paleoceanographic application of Nd isotopes in the South Pacific.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/b