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Sample records for alkaline igneous complex

  1. Petrochemical nature of baradangua alkaline igneous complex, Orissa, India

    NASA Astrophysics Data System (ADS)

    Das, Madhumita; Acharya, S.

    The Baradangua alkaline complex on the southern bank of the Brahmani river, Orissa, strikes E-W with steep southerly dips, in conformity with the regional trend of the litho units of the Eastern Ghat Mobile Belt of this sector. The nepheline syenite, a hypersolvus rock, comprises potash feldspar, nepheline, plagioclase and calcite, with biotite as the dominant mafic mineral. The agpaitic index [ {( Na2O + K2O) }/{Al2O3} mol prop] ranges from 0.43 to 0.74 in the nepheline syenites, indicating their miaskitic nature. Field, petrography and geochemistry suggest a magmatic origin for nepheline syenites, the differentiation pattern being reflected by the distribution of the trace elements.

  2. Anisotropy of the Magnetic Susceptibility of the Alnö alkaline and carbonatite igneous complex

    NASA Astrophysics Data System (ADS)

    Andersson, M.; Almqvist, B.; Malehmir, A.; Troll, V. R.; Snowball, I.; Lougheed, B.

    2013-12-01

    The Alnö igneous complex in central Sweden is one of the largest (radius ~2.5 km) of the few well-known alkaline and carbonatite ring-intrusions in the world. The lithologies span from alkaline silicate rocks (nepheline syenite, ijolite, and pyroxenite) to a range of carbonatite dykes (e.g. sövite) with variable composition. The depth extent, dip, and dip direction of the alkaline and carbonatite rocks have been inferred from surface geological mapping, and a dome-shaped magma chamber with the roof at ~2 km below the palaeosurface was inferred to have supplied steeply dipping radial dykes and (shallowly dipping) cone sheets. Recent high-resolution reflection seismic profiles and gravity and ground magnetic measurements suggest, in turn, a saucer-shaped magma chamber at ~3 km depth below present day land surface. To provide further insight into the internal flow mechanics of these dykes and into their emplacement mechanisms, we have measured the anisotropy of magnetic susceptibility (AMS). About 250 samples from 119 oriented cores were collected with a handheld drilling machine from 26 localities within the Alnö complex. Prior to preparation of discrete samples for AMS, the cores were measured for their density and for ultrasonic P- and S-wave velocities. Most of the sampling locations lie on a transect through the intrusion. Three locations have been sampled in detail, to determine the variation of AMS within individual carbonatite dykes. The AMS of samples were measured in low-field, using a KLY-2 Kappabridge. Bulk magnetic susceptibility ranges from 3.01e-5 to 2.50e-1 SI, and correlates with lithology. The sövites have the widest range of susceptibility (average 4.32e-2, with a range from 3.01e-5 to 2.50e-1 SI), whereas fenites have the lowest average susceptibility (average 2.06e-3, with a range from 9.86e-5 to 1.47e-2 SI); nepheline-syenite, ijolite and pyroxenite have susceptibilities between these two end member lithologies. Sövite consists mainly of

  3. Phlogopite- and clinopyroxene-dominated fractional crystallization of an alkaline primitive melt: petrology and mineral chemistry of the Dariv Igneous Complex, Western Mongolia

    NASA Astrophysics Data System (ADS)

    Bucholz, Claire E.; Jagoutz, Oliver; Schmidt, Max W.; Sambuu, Oyungerel

    2014-04-01

    We present field relationships, petrography, and mineral major and trace element data for the Neoproterozoic Dariv Igneous Complex of the Altaids of Western Mongolia. This unique complex of high-K plutonic rocks is composed of well-exposed, km-scale igneous intrusions of wehrlites, phlogopite wehrlites, apatite-bearing phlogopite clinopyroxenites, monzogabbros, monzodiorites, and clinopyroxene-bearing monzonites, all of which are intruded by late stage lamprophyric and aplitic dikes. The biotite-dominated igneous complex intrudes depleted harzburgitic serpentinite. The observed lithological variability and petrographic observations suggest that the plutonic rocks can be ascribed to a fractionation sequence defined by olivine + clinopyroxene ± Fe-Ti oxides → phlogopite + apatite → K-feldspar + plagioclase → amphibole + quartz. Notably, phlogopite is the dominant hydrous mafic mineral. Petrogenesis of the observed lithologies through a common fractionation sequence is supported by a gradual decrease in the Mg# [molar Mg/(Fetotal + Mg) × 100] of mafic minerals. Crystallization conditions are derived from experimental phase petrology and mineral chemistry. The most primitive ultramafic cumulates crystallized at ≤0.5 GPa and 1,210-1,100 °C and oxygen fugacity ( fO2) of +2-3 ∆FMQ (log units above the fayalite-quartz-magnetite buffer). Trace element modeling using clinopyroxene and apatite rare earth element compositions indicates that the dominant mechanism of differentiation was fractional crystallization. The trace element composition of a parental melt was calculated from primitive clinopyroxene compositions and compares favorably with the compositions of syn-magmatic lamprophyres that crosscut the fractionation sequence. The parental melt composition is highly enriched in Th, U, large ion lithophile elements, and light rare earth elements and has a pronounced negative Nb-Ta depletion, suggestive of an alkaline primitive melt originating from a subduction

  4. Petrology and mineralogy of the La Peña igneous complex, Mendoza, Argentina: An alkaline occurrence in the Miocene magmatism of the Southern Central Andes

    NASA Astrophysics Data System (ADS)

    Pagano, Diego Sebastián; Galliski, Miguel Ángel; Márquez-Zavalía, María Florencia; Colombo, Fernando

    2016-04-01

    The La Peña alkaline igneous complex (LPC) is located in the Precordillera (32°41‧34″ S - 68°59‧48″ W) of Mendoza province, Argentina, above the southern boundary of the present-day flat-slab segment. It is a 19 km2 and 5 km diameter subcircular massif emplaced during the Miocene (19 Ma) in the Silurian-Devonian Villavicencio Fm. The LPC is composed of several plutonic and subvolcanic intrusions represented by: a cumulate of clinopyroxenite intruded by mafic dikes and pegmatitic gabbroic dikes, isolated bodies of malignite, a central intrusive syenite that develops a wide magmatic breccia in the contact with clinopyroxenite, syenitic and trachytic porphyries, a system of radial and ring dikes of different compositions (trachyte, syenite, phonolite, alkaline lamprophyre, tephrite), and late mafic breccias. The main minerals that form the LPC, ordered according to their abundance, are: pyroxene (diopside, hedenbergite), calcium amphibole (pargasite, ferro-pargasite, potassic-ferro-pargasite, potassic-hastingsite, magnesio-hastingsite, hastingsite, potassic-ferro-ferri-sadanagaite), trioctahedral micas (annite-phlogopite series), plagioclase (bytownite to oligoclase), K-feldspar (sanidine and orthoclase), nepheline, sodalite, apatite group minerals (fluorapatite, hydroxylapatite), andradite, titanite, magnetite, spinel, ilmenite, and several Cu-Fe sulfides. Late hydrothermal minerals are represented by zeolites (scolecite, thomsonite-Ca), epidote, calcite and chlorite. The trace element patterns, coupled with published data on Sr-Nd-Pb isotopes, suggest that the primary magma of the LPC was generated in an initially depleted but later enriched lithospheric mantle formed mainly by a metasomatized spinel lherzolite, and that this magmatism has a subduction-related signature. The trace elements pattern of these alkaline rocks is similar to other Miocene calc-alkaline occurrences from the magmatic arc of the Southern Central Andes. Mineral and whole

  5. Petrology, geochemistry, and mineralogy of pyroxene and pegmatitic carbonatite and the associated fluorspar deposit at Okorusu alkaline igneous carbonatite complex, Namibia

    NASA Astrophysics Data System (ADS)

    Shivdasan, Purnima Ashok

    Field observations, petrography, electron microprobe analysis (EPMA), geothermometry, and geochemical analyses (ICP-MS and XRF) of the fluorspar deposit associated with the Late Cretaceous alkaline igneous-carbonatite complex at Okorusu (Namibia) have identified two previously unrecognized types of carbonatites, namely pyroxene and pegmatitic carbonatites. These carbonatites exhibit interesting textural characteristics, with the pyroxene carbonatite exhibiting occasional bands of diopside alternating with coarse-grained calcite-rich bands, and pegmatitic carbonatite having the same mineralogy but much coarser texture. Both types of carbonatites are closely spatially associated. Ulvospinel ex-solution lamellae were recognized in magnetite crystals within the pyroxene and pegmatitic carbonatite. Stable isotope determinations for calcite crystals separated from pegmatitic carbonatites, pyroxene carbonatites, and marbles indicate that the carbonatites are primary in origin. Cathodoluminescence microscopy (CL) and emission spectrography of the carbonatites indicated that the carbonate mineral is almost entirely calcite rather than dolomite, and there are at least two generations of calcite. CL study of fenites, which are metasomatised Precambrian metasedimentary rocks, intruded by carbonatites reveal that fenitization is mostly incipient, marked by the introduction of Fe3+ activated feldspars. Geothermometric determination from EPMA of apatite and biotite in pyroxene carbonatite provided a range of 537--409°C except in one sample which clearly indicated later hydrothermal alteration. The temperature range is similar to a previous titaniferous magnetite-ilmenite temperature determination and is interpreted to represent magmatic crystallization. Trace element patterns of carbonatites are largely consistent with the results of previous studies, although phosphorus values are anomalously high because of apatite. As one of only two producing carbonatite-related fluorspar

  6. Sudbury Igneous Complex: Impact melt or igneous rock? Implications for lunar magmatism

    NASA Technical Reports Server (NTRS)

    Norman, Marc D.

    1992-01-01

    The recent suggestion that the Sudbury Igneous Complex (SIC) is a fractionated impact melt may have profound implications for understanding the lunar crust and the magmatic history of the Moon. A cornerstone of much current thought on the Moon is that the development of the lunar crust can be traced through the lineage of 'pristine' igneous rocks. However, if rocks closely resembling those from layered igneous intrusions can be produced by differentiation of a large impact melt sheet, then much of what is thought to be known about the Moon may be called into question. This paper presents a brief evaluation of the SIC as a differentiated impact melt vs. endogenous igneous magma and possible implications for the magmatic history of the lunar crust.

  7. Alkaline igneous rocks of Magnet Cove, Arkansas: Mineralogy and geochemistry of syenites

    USGS Publications Warehouse

    Flohr, M.J.K.; Ross, M.

    1990-01-01

    Syenites from the Magnet Cove alkaline igneous complex form a diverse mineralogical and geochemical suite. Compositional zoning in primary and late-stage minerals indicates complex, multi-stage crystallization and replacement histories. Residual magmatic fluids, rich in F, Cl, CO2 and H2O, reacted with primary minerals to form complex intergrowths of minerals such as rinkite, fluorite, V-bearing magnetite, F-bearing garnet and aegirine. Abundant sodalite and natrolite formed in pegmatitic segregations within nepheline syenite where Cl- and Na-rich fluids were trapped. During autometasomatism compatible elements such as Mn, Ti, V and Zr were redistributed on a local scale and concentrated in late-stage minerals. Early crystallization of apatite and perovskite controlled the compatible behavior of P and Ti, respectively. The formation of melanite garnet also affected the behaviour of Ti, as well as Zr, Hf and the heavy rare-earth elements. Pseudoleucite syenite and garnet-nepheline syenite differentiated along separate trends, but the two groups are related to the same parental magma by early fractionation of leucite, the presumed precursor of intergrowths of K-feldspar and nepheline. The Diamond Jo nepheline syenite group defines a different differentiation trend. Sphene-nepheline syenite, alkali syenite and several miscellaneous nepheline syenites do not consistently plot with the other syenite groups or each other on element and oxide variation diagrams, indicating that they were derived from still other parental syenite magmas. Mineral assemblages indicate that relatively high f{hook};O2, at or above the fayalite-magnetite-quartz buffer, prevailed throughout the crystallization history of the syenites. ?? 1990.

  8. Magnetic modeling of the Bushveld Igneous Complex

    NASA Astrophysics Data System (ADS)

    Webb, S. J.; Cole, J.; Letts, S. A.; Finn, C.; Torsvik, T. H.; Lee, M. D.

    2009-12-01

    Magnetic modeling of the 2.06 Ga Bushveld Complex presents special challenges due a variety of magnetic effects. These include strong remanence in the Main Zone and extremely high magnetic susceptibilities in the Upper Zone, which exhibit self-demagnetization. Recent palaeomagnetic results have resolved a long standing discrepancy between age data, which constrain the emplacement to within 1 million years, and older palaeomagnetic data which suggested ~50 million years for emplacement. The new palaeomagnetic results agree with the age data and present a single consistent pole, as opposed to a long polar wander path, for the Bushveld for all of the Zones and all of the limbs. These results also pass a fold test indicating the Bushveld Complex was emplaced horizontally lending support to arguments for connectivity. The magnetic signature of the Bushveld Complex provides an ideal mapping tool as the UZ has high susceptibility values and is well layered showing up as distinct anomalies on new high resolution magnetic data. However, this signature is similar to the highly magnetic BIFs found in the Transvaal and in the Witwatersrand Supergroups. Through careful mapping using new high resolution aeromagnetic data, we have been able to map the Bushveld UZ in complicated geological regions and identify a characteristic signature with well defined layers. The Main Zone, which has a more subdued magnetic signature, does have a strong remanent component and exhibits several magnetic reversals. The magnetic layers of the UZ contain layers of magnetitite with as much as 80-90% pure magnetite with large crystals (1-2 cm). While these layers are not strongly remanent, they have extremely high magnetic susceptibilities, and the self demagnetization effect must be taken into account when modeling these layers. Because the Bushveld Complex is so large, the geometry of the Earth’s magnetic field relative to the layers of the UZ Bushveld Complex changes orientation, creating

  9. Emplacement of the La Peña alkaline igneous complex, Mendoza, Argentina (33° S): Implications for the early Miocene tectonic regime in the retroarc of the Andes

    NASA Astrophysics Data System (ADS)

    Pagano, D. S.; Galliski, M. A.; Márquez-Zavalía, M. F.

    2014-03-01

    The La Peña alkaline complex (LPC) of Miocene age (18-19 Ma) lies on the eastern front of the Precordillera (32°41ʹ34ʺS, 68°59ʹ48″W, 1400-2900 m a.s.l.), 30 km northwest of Mendoza city, Argentina. It is a subcircular massif of 19 km2 and 5 km in diameter, intruded in the metasedimentary sequence of the Villavicencio Formation of Silurian-Devonian age. It is the result of integration of multiple pulses derived from one or more deep magma chambers, which form a suite of silicate rocks grouped into: a clinopyroxenite body, a central syenite facies with a large breccia zone at the contact with the clinopyroxenite, bodies of malignite, trachyte and syenite porphyry necks, and a system of radial and annular dikes of different compositions. Its subcircular geometry and dike system distribution are frequent features of intraplate plutons or plutons emplaced in post-orogenic settings. These morphostructural features characterize numerous alkaline complexes worldwide and denote the importance of magmatic pressures that cause doming with radial and annular fracturing, in a brittle country rock. However, in the LPC, the attitude of the internal fabric of plutonic and subvolcanic units and the preferential layout of dikes match the NW-SE extensional fractures widely distributed in the host rock. This feature indicates a strong tectonic control linked to the structure that facilitate space for emplacement, corresponding to the brittle shear zone parallel to the N-S stratigraphy of the country rock. Shearing produced a system of discontinuities, with a K fractal fracture pattern, given by the combination of Riedel (R), anti-Riedel (R‧), (P) and extensional (T) fracture systems, responsible for the control of melt migration by the opening of various fracture branches, but particularly through the NW-SE (T) fractures. Five different pulses would have ascent, (1) an initial one from which cumulate clinopyroxenite was formed, (2) a phase of mafic composition represented by

  10. Evidence for alkaline igneous activity and associated metasomatism in the Reelfoot rift, south-central Midcontinent, U. S. A

    SciTech Connect

    Goldhaber, M.B.; Diehl, S.F.; Sutley, S.J. ); Flohr, M.J.K. )

    1993-03-01

    Alkaline igneous magmatism is commonly associated with intracontinental rifts such as the Reelfoot rift (RR). Direct evidence for alkaline magmatism in the area of the RR occurs as lamprophyre and syenite encountered in deep wells. The authors' new studies of lamprophyres and sedimentary rocks from wells in the region provide additional examples of alkaline magmatism and emphasize the effects of related metasomatism. Sedimentary rocks in the Dow Chemical No. 1 Garrigan well, which is not known to contain lamprophyre dikes, probably also were metasomatically altered, as they contain authigenic fluorapatite, Ce-phosphates, and other REE-rich minerals. Enrichments of incompatible and large ion lithophile elements commonly associated with alkaline magmatism occur in the New Madrid test well, near the crest of the Pascola Arch. The carbonate-free fraction of Paleozoic rocks in this well is highly enriched in Nb (500 ppm), Ba (> 5,000 ppm), La (500 ppm), Th (1,000 ppm), and F (2,400 ppm). Abundant inclusion-rich potassium-feldspar cement in a nearby well may also be the result of alkaline metasomatism. Fluorite and elevated F concentrations are found in several wells in the RR, and contrast with stratigraphically correlative platform carbonates of the Ozark uplift, which lack F enrichment. Well and spring water samples above the RR are enriched in fluorine (as much as 5,000 ppb) compared to samples away from the rift which typically have concentrations two orders of magnitude smaller. The data and observations are consistent with relatively widespread alkaline metasomatism, which was associated with the intrusion of alkaline magmas in the RR.

  11. Recrystallized Impact Glasses of the Onaping Formation and the Sudbury Igneous Complex, Sudbury Structure, Ontario, Canada

    NASA Technical Reports Server (NTRS)

    Dressler, B. O.; Weiser, T.; Brockmeyer, P.

    1996-01-01

    The origin of the Sudbury Structure and of the associated heterolithic breccias of the Onaping Formation and the Sudbury Igneous Complex have been controversial. While an impact origin of the structure has gained wide acceptance over the last 15 years, the origin of the recrystallized Onaping Formation glasses and of the igneous complex is still being debated. Recently the interpretation of the breccias of the Onaping Formation as suevitic fall-back impact breccias has been challenged. The igneous complex is interpreted either as a differentiated impact melt sheet or as a combination of an upper impact melt represented by the granophyre, and a lower, impact-triggered magmatic body consisting of the norite-sublayer formations. The Onaping Formation contains glasses as fluidal and nonfluidal fragments of various shapes and sizes. They are recrystallized, and our research indicates that they are petrographically heterogeneous and span a wide range of chemical compositions. These characteristics are not known from glasses of volcanic deposits. This suggests an origin by shock vitrification, an interpretation consistent with their association with numerous and varied country rock clasts that exhibit microscopic shock metamorphic features. The recrystallized glass fragments represent individual solid-state and liquid-state vitrified rocks or relatively small melt pods. The basal member lies beneath the Gray and Black members of the Onaping Formation and, where not metamorphic, has an igneous matrix. Igneous-textured melt bodies occur in the upper two members and above the Basal Member. A comparison of the chemical compositions of recrystallized glasses and of the matrices of the Basal Member and the melt bodies with the components and the bulk composition of the igneous complex is inconclusive as to the origin of the igneous complex. Basal Member matrix and Melt Bodies, on average, are chemically similar to the granophyre of the Sudbury Igneous Complex, suggesting that

  12. Magmatic complexes of the Urals as suspect parts of Large Igneous Provinces

    NASA Astrophysics Data System (ADS)

    Puchkov, Victor

    2016-10-01

    Petrogenetic, geochemical studies and isotope age determinations of flood basalts, dolerites, trachybasalts, picrite-basalts, rapakivi granites, layered mafic-ultramafic intrusions and also alkaline and carbonatite magmatic complexes of the Urals permit to put forward a preliminary list of objects - “candidates” at being attributed to Large Igneous Provinces (LIPs) - manifestations of superplume activity. Their petro-geochemical properties distinguish them from spreading and subduction types, and are closer to epicontinental rift zones. They are characterized by wide areas of development and very short periods of activity. In the Southern Urals near the base of the Lower Riphean (Uppermost Paleoproterozoic and Lower Mesoproterozoic) there are volcanic deposits of the Navysh Subformation, represented by trachybasalts. The age of the unit was determined as 1752 ± llMa. Volcanic rocks of the age level of 1750-1780 Ma are developed not only in some other places of Baltica, but also in the Northern Africa, Siberia, Laurentia (parts of Nuna supercontinent). Therefore, they may belong to a LIP. Higher up the section of the Riphean, at the base of the Middle Riphean (Mid-Mesoproterozoic), rhyolites of the basalt-rhyolite Mashak Formation were dated as 1380-1385 Ma. The same ages have also rapakivi granites, layered gabbro, carbonatites and dolerite dykes developed in the Southern Urals and encountered in boreholes of the East European platform; magmatic rocks of the same age are traced to Laurentia and Siberian cratons and date the beginning of Nuna supercontinent break-up. Less confidently we may speak of the younger Neoproterozoic magmatic complexes of the Southern Urals as LIPs, dated as ca. 720 Ma and 680 Ma (Arshinian and Kiryabinka complexes); they need a further study. The next in the succession of magmatic episodes, represented by subalkaline volcanics, is connected with a rift process that started at ca. 490 Ma, that led to oceanic spreading and formation of

  13. The Late Cretaceous Alkaline Igneous Province in the Iberian Peninsula, and its tectonic significance

    NASA Astrophysics Data System (ADS)

    Rock, N. M. S.

    1982-04-01

    The Iberian Province consists of the following: the three subvolcanic, syenitic, major intrusive complexes of Monchique, Sines and Sintra in W. and SW Portugal, together with their basanitic/lamprophyric minor intrusive suites; basanitic volcanic complexes around Lisbon; at least some of a widespread suite of basanitic to theralitic minor intrusives in west central Portugal; about 80 small basanitic/lamprophyric to nepheline syenitic intrusions scattered through the Pyrenees, NE Spain, the French Corbières, and off the coast of NW Spain; and the Ormonde Seamount of the Gorringe Bank off the SW coast of Portugal. Most of these occurrences have been dated isotopically or from field evidence as Late Cretaceous. Geological and petrological details of the various occurrences are compiled and reviewed. Primary basanitic magmas were probably parental to the entire Province, and generated syenitic magmas by differentiation processes; oversaturated rocks were produced by alkali loss and perhaps also by crustal involvement. The Iberian Province is related to the opening of the N. Atlantic, specifically that of the Bay of Biscay.

  14. Isotopic ages for alkaline igneous rocks, including a 26 Ma ignimbrite, from the Peshawar plain of northern Pakistan and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Ahmad, Irshad; Khan, Shuhab; Lapen, Thomas; Burke, Kevin; Jehan, Noor

    2013-01-01

    New isotopic ages on zircons from rocks of the Peshawar Plain Alkaline Igneous Province (PPAIP) reveal for the first time the occurrence of ignimbritic Cenozoic (Oligocene) volcanism in the Himalaya at 26.7 ± 0.8 Ma. Other new ages confirm that PPAIP rift-related igneous activity was Permian and lasted from ˜290 Ma to ˜250 Ma. Although PPAIP rocks are petrologically and geochemically typical of rifts and have been suggested to be linked to rifting on the Pangea continental margin at the initiation of the Neotethys Ocean, there are no documented rift-related structures mapped in Permian rocks of the Peshawar Plain. We suggest that Permian rift-related structures have been dismembered and/or reactivated during shortening associated with India-Asia collision. Shortening in the area between the Main Mantle Thrust (MMT) and the Main Boundary Thrust (MBT) may be indicative of the subsurface northern extension of the Salt Range evaporites. Late Cenozoic sedimentary rocks of the Peshawar Plain deposited during and after Himalayan thrusting occupy a piggy-back basin on top of the thrust belt. Those sedimentary rocks have buried surviving evidence of Permian rift-related structures. Igneous rocks of the PPAIP have been both metamorphosed and deformed during the Himalayan collision and Cenozoic igneous activity, apart from the newly recognized Gohati volcanism, has involved only the intrusion of small cross-cutting granitic bodies concentrated in areas such as Malakand that are close to the MMT. Measurements on Chingalai Gneiss zircons have confirmed the occurrence of 816 ± 70 Ma aged rocks in the Precambrian basement of the Peshawar Plain that are comparable in age to rocks in the Malani igneous province of the Rajasthan platform ˜1000 km to the south.

  15. The growth of large mafic intrusions: Comparing Niquelândia and Ivrea igneous complexes

    NASA Astrophysics Data System (ADS)

    Correia, Ciro Teixeira; Sinigoi, Silvano; Girardi, Vicente Antonio Vitorio; Mazzucchelli, Maurizio; Tassinari, Colombo Celso Gaeta; Giovanardi, Tommaso

    2012-12-01

    The Niquelândia Complex, Brazil, is one of the world's largest mafic-ultramafic plutonic complexes. Like the Mafic Complex of the Ivrea-Verbano Zone, it is affected by a pervasive high-T foliation and shows hypersolidus deformation structures, contains significant inclusions of country-rock paragneiss, and is subdivided into a Lower and an Upper Complex. In this paper, we present new SHRIMP U-Pb zircon ages that provide compelling evidence that the Upper and the Lower Niquelândia Complexes formed during the same igneous event at ca. 790 Ma. Coexistence of syn-magmatic and high-T subsolidus deformation structures indicates that both complexes grew incrementally as large crystal mush bodies which were continuously stretched while fed by pulses of fresh magma. Syn-magmatic recrystallization during this deformation resulted in textures and structures which, although appearing metamorphic, are not ascribable to post-magmatic metamorphic event(s), but are instead characteristic of the growth process in huge and deep mafic intrusions such as both the Niquelândia and Ivrea Complexes. Melting of incorporated country-rock paragneiss continued producing hybrid rocks during the last, vanishing stages of magmatic crystallization. This resulted in the formation of minor, late-stage hybrid rocks, whose presence obscures the record of the main processes of interaction between mantle magmas and crustal components, which may be active at the peak of the igneous events and lead to the generation of eruptible hybrid magmas.

  16. Synmagmatic deformation in the underplated igneous complex of the Ivrea-Verbano zone

    USGS Publications Warehouse

    Quick, J.E.; Sinigoi, S.; Negrini, L.; Demarchi, G.; Mayer, A.

    1992-01-01

    The Ivrea-Verbano zone, northern Italy, contains an igneous complex up to 10km thick that is thought to have been intruded near the interface between the continental crust and mantle during the late Paleozoic. New data indicate that this complex is pervasively deformed and concentrically foliated. The presence of analogous features in ophiolitic gabbros suggests that emplacement of the Ivrea-Verbano zone plutonic rocks involved large-scale flow of crystal mush in a dynamic, and possibly extensional, tectonic environment. -from Authors

  17. Distribution of chemical elements in calc-alkaline igneous rocks, soils, sediments and tailings deposits in northern central Chile

    NASA Astrophysics Data System (ADS)

    Oyarzún, Jorge; Oyarzun, Roberto; Lillo, Javier; Higueras, Pablo; Maturana, Hugo; Oyarzún, Ricardo

    2016-08-01

    This study follows the paths of 32 chemical elements in the arid to semi-arid realm of the western Andes, between 27° and 33° S, a region hosting important ore deposits and mining operations. The study encompasses igneous rocks, soils, river and stream sediments, and tailings deposits. The chemical elements have been grouped according to the Goldschmidt classification, and their concentrations in each compartment are confronted with their expected contents for different rock types based on geochemical affinities and the geologic and metallogenic setting. Also, the element behavior during rock weathering and fluvial transport is here interpreted in terms of the ionic potentials and solubility products. The results highlight the similarity between the chemical composition of the andesites and that of the average Continental Crust, except for the higher V and Mn contents of the former, and their depletion in Mg, Ni, and Cr. The geochemical behavior of the elements in the different compartments (rocks, soils, sediments and tailings) is highly consistent with the mobility expected from their ionic potentials, their sulfates and carbonates solubility products, and their affinities for Fe and Mn hydroxides. From an environmental perspective, the low solubility of Cu, Zn, and Pb due to climatic, chemical, and mineralogical factors reduces the pollution risks related to their high to extremely high contents in source materials (e.g., rocks, altered zones, tailings). Besides, the complex oxyanions of arsenic get bound by colloidal particles of Fe-hydroxides and oxyhydroxides (e.g., goethite), thus becoming incorporated to the fine sediment fraction in the stream sediments.

  18. Pre-Elsonian mafic magmatism in the Nain Igneous Complex, Labrador: the bridges layered intrusion

    USGS Publications Warehouse

    Ashwal, L.D.; Wiebe, R.A.; Wooden, J.L.; Whitehouse, M.J.; Snyder, Diane

    1992-01-01

    Decades of work on the pristine, unmetamorphosed, and well exposed anorthositic, mafic and granitic rocks of the Nain igneous complex, Labrador, have led to the conclusion that all plutonic rocks in that area were emplaced in a short time intercal at about 1300 ?? 10 Ma). We report here new isotopic data for mafic intrusive rocks that appear to have crystallized several hundred Ma earlier than the bulk of the plutonic activity in the Nain complex. The Bridges layered intrusion (BLI) is a small (15-20 km2) lens of layered mafic rocks about 1.5 km thick, surrounded and intruded by anorthositic, leuconoritic and leucotroctolitic plutons in the middle of the coastal section of the Nain igneous complex. BLI shows very well developed magmatic structures, including channel scours, slump structures, and ubiquitous modally graded layering. Most rocks, however, show granular textures indicative of recrystallization, presumably caused by emplacement of younger anorthositic rocks. BLI contains cumulate rocks with slightly more primitive mineral compositions (An60-83, Fo66-71) than those of other mafic intrusions in the Nain igneous complex, including Kiglapait. SmNd isotopic data for 7 BLI whole-rocks ranging in composition between olivine melagabbro and olivine leucogabbro yield an age of 1667 ?? 75 Ma, which we interpret as the time of primary crystallization. The internal isotopic systematics of the BLI have been reset, probably by intrusion of adjacent anorthositic plutons. A SmNd mineral isochron (plag, whole-rock, mafics) for a BLI olivine melagabbro gives an age of 1283 ?? 22 Ma, equivalent within error of a mineral array (plag, whole-rock, opx, cpx) for an adjacent, igneous-textured, leuconorite vein (1266 ?? 152 Ma). The initial Nd ratio for BLI corresponds to ??{lunate}Nd = -3.18 ?? 0.44. Other whole-rock samples, however, some with vein-like alteration (Chlorite, serpentine, amphiboles), show ??{lunate}Nd values as low as -9.1, suggesting variable contamination by

  19. Intrusive origin of the Sudbury Igneous Complex: Structural and sedimentological evidence

    NASA Technical Reports Server (NTRS)

    Cowan, E. J.; Schwerdtner, W. M.

    1992-01-01

    In recent years, many geoscientists have come to believe that the Sudbury event was exogenic rather than endogenic. Critical to a recent exogenic hypothesis is the impact melt origin of the Sudbury Igneous Complex (SIC). Such origin implies that the SIC was emplaced before deposition of the Whitewater Group, in contrast to origins in which the SIC postdates the lithification of the Onaping Formation. Structural and sedimentological evidence is summarized herein that supports an intrusion of the SIC after lithification of all Whitewater Group strata, and conflicts with the hypothesis advanced by other researchers.

  20. Drilling through the largest magma chamber on Earth: Bushveld Igneous Complex Drilling Project (BICDP)

    NASA Astrophysics Data System (ADS)

    Trumbull, R. B.; Ashwal, L. D.; Webb, S. J.; Veksler, I. V.

    2015-05-01

    A scientific drilling project in the Bushveld Igneous Complex in South Africa has been proposed to contribute to the following scientific topics of the International Continental Drilling Program (ICDP): large igneous provinces and mantle plumes, natural resources, volcanic systems and thermal regimes, and deep life. An interdisciplinary team of researchers from eight countries met in Johannesburg to exchange ideas about the scientific objectives and a drilling strategy to achieve them. The workshop identified drilling targets in each of the three main lobes of the Bushveld Complex, which will integrate existing drill cores with new boreholes to establish permanently curated and accessible reference profiles of the Bushveld Complex. Coordinated studies of this material will address fundamental questions related to the origin and evolution of parental Bushveld magma(s), the magma chamber processes that caused layering and ore formation, and the role of crust vs. mantle in the genesis of Bushveld granites and felsic volcanic units. Other objectives are to study geophysical and geodynamic aspects of the Bushveld intrusion, including crustal stresses and thermal gradient, and to determine the nature of deep groundwater systems and the biology of subsurface microbial communities.

  1. Palaeomagnetism of the Early Permian Mount Leyshon Intrusive Complex and Tuckers Igneous Complex, North Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Clark, D. A.; Lackie, M. A.

    2003-06-01

    This study provides reliable, precisely defined and well-dated Early Permian (286 +/- 6 Ma) palaeomagnetic poles for Australia from the Mount Leyshon Intrusive Complex (MLIC) and the Tuckers Igneous Complex (TIC). Both complexes are associated with prominent negative magnetic anomalies, indicating the presence of rocks carrying stable remanence of reverse polarity, with a Koenigsberger ratio greater than unity. The characteristic remanence carried by the intrusive phases and by locally remagnetized, contact-metamorphosed host rocks is always of reverse polarity, consistent with acquisition during the Permo-Carboniferous (Kiaman) Reverse Superchron. The corresponding palaeopoles confirm that Australia occupied high latitudes in the Early Permian. The pole positions are: MLIC: lat. = 43.2 °S, long. = 137.3 °E dp = 6.0°, dm = 6.4° Q= 6; TIC: lat. = 47.5 °S, long. = 143.0 °E, dp = 6.0°, dm = 6.6° Q= 6. Permian palaeomagnetic overprinting is detectable at considerable distances from the MLIC (2-3 km), well beyond the zone of visible alteration. The primary nature of the Early Permian palaeomagnetic signature is established by full baked contact/aureole tests at both localities. Other new data from Australia are consistent with the poles reported here. Comparison of the Australian, African and South American Apparent Polar Wander Paths (APWP) suggests that mean Permian and Triassic poles from West Gondwana, particularly from South America, are biased by remagnetization in the Jurassic-Cretaceous and that the Late Palaeozoic-Mesozoic APWP for Gondwana is best defined by Australian data. The Australian APWP exhibits substantial movement through the Mesozoic. Provided only that the time-averaged palaeofield was zonal, the Early Triassic palaeomagnetic data from Australia provide an important palaeogeographic constraint that the south geographic pole was within, or very close to, SE Australia around 240 Ma. The new Early Permian poles are apparently more consistent

  2. A trishear model for the deformation of the Sudbury Igneous Complex, Canada

    NASA Astrophysics Data System (ADS)

    Lenauer, Iris; Riller, Ulrich

    2017-04-01

    The Sudbury Igneous Complex (SIC), Canada, is an impact-induced layered sheet of crystalline rocks deformed into an asymmetrical fold basin, the Sudbury Basin. The basin geometry at depth is largely unknown as few attempts were made to quantify displacement and rotation of layer contacts. We propose that the dip of layer contacts and foliation surfaces in the southern SIC can be approximated by trishear fault propagation folding. Trishear deformation accounts for: (1) angular discordances between upper and basal SIC contacts, (2) local overturning of the SIC, (3) progressive steepening of foliation surfaces from NW to SE, (4) strain gradient in the Sudbury Basin sedimentary rocks, and (5) thickness variations in SIC layers. Moreover, the South Range Shear Zone, a zone of moderately strong metamorphic fabrics, coincides with the surface manifestation of the proposed trishear zone. We demonstrate the use of structural data together with forward kinematic modelling to identify the strain distribution within the SIC, rotation of SIC contacts and thickness changes of SIC layers. Backward kinematic modelling provides information on the initial geometry of the SIC and is used to restore the shape of the igneous sheet, showing that the SIC was shortened by approximately 10 km in NW-SE diameter. Most of the shortening was accommodated by 40% reduction in the thickness of the upper SIC layer.

  3. Tungsten anomalies in the Uyaijah ring structure, Kushaymiyah igneous complex, Kingdom of Saudi Arabia - Section A, Geology and geochemistry of the Uyaijah ring structure; Section B, Regional geophysics

    USGS Publications Warehouse

    Theobald, P.K.; Allcott, Glenn H.; Flanigan, Vincent J.; Andeasen, Gordon E.

    1975-01-01

    Anomalous amounts of tungsten, molybdenum, and bismuth are present in the Uyaijah ring structure of the Kushaymiyah igneous complex in the eastern part of the Precambrian shield of the Kingdom of Saudi Arabia. The complex includes four major rock units, the Murdama Group, porphyritic granodiorite, quartz monzonite, alkaline granite, and areas enriched in silica. Structural and compositional relationships among some of the rock units are defined in part by aeromagnetic and gamma-ray spectrometric geophysical data. Geochemical data from -10 +30 mesh surficial debris were primarily related to the composition of the major rock units, whereas data from heavy-mineral concentrates were used to establish the location of tungsten-molybdenum-bismuth anomalies. Two areas of about 40 sq km each are occupied by tungsten-molybdenum-bismuth anomalies interpreted to be related to the alkaline granite. One of these is a contact metasomatic anomaly; the other is related to leakage from an inferred underlying cupola of the alkaline granite. These two anomalous areas are recommended for further investigation

  4. LA-ICP-MS mineral chemistry of titanite and the geological implications for exploration of porphyry Cu deposits in the Jinshajiang - Red River alkaline igneous belt, SW China

    NASA Astrophysics Data System (ADS)

    Xu, Leiluo; Bi, Xianwu; Hu, Ruizhong; Tang, Yongyong; Wang, Xinsong; Xu, Yue

    2015-04-01

    The Jinshajiang-Red River alkaline igneous belt in the eastern Indian-Asian collision zone, of southwestern China, hosts abundant, economically important Cu-Mo-Au mineralization of Cenozoic age. Major- and trace-element compositions of titanites from representative Cu-mineralized intrusions determined by LA-ICP-MS show higher values for Fe2O3/Al2O3, ΣREE + Y, LREE/HREE, Ce/Ce*, (Ce/Ce*)/(Eu/Eu*), U, Th, Ta, Nb and Ga, and lower values for Al2O3, CaO, Eu/Eu*, Zr/Hf, Nb/Ta and Sr than those for titanites from barren intrusions. Different ΣREE + Y, LREE/HREE, U, Th, Ta and Nb values of titanites between Cu-mineralized and barren intrusions were controlled mainly by the coexisting melt compositions. However, different Sr concentrations and negative Eu anomalies of titanites between Cu-mineralized and barren intrusions were most probably caused by different degrees of crystallization of feldspar from melts. In addition, different Ga concentrations and positive Ce anomalies of titanites between Cu-mineralized and barren intrusions were most likely caused by different magmatic fO2 conditions. Pronounced compositional differences of titanites between Cu-mineralized and barren intrusions can provide a useful tool to help discriminate between ore-bearing and barren intrusions at an early stage of exploration, and, thus, have a potential application in exploration for porphyry Cu deposits in the Jinshajiang - Red River alkaline igneous belt, and to other areas.

  5. Deep structure of the Mount Amram igneous complex, interpretation of magnetic and gravity data

    NASA Astrophysics Data System (ADS)

    Shirman, Boris; Rybakov, Michael; Beyth, Michael; Mushkin, Amit; Ginat, Hanan

    2015-03-01

    The Mt Amram igneous complex (AIC) represents northern tip of the Neoproterozoic Arabian Nubian Shield (ANS). For the first time the AIC deep structure was studied using the gravity, aero and ground magnetic, magnetic susceptibility and density measurements and geological data. Analysing all available data at the Amram area we concluded what only monzonite body can be reason for gravity high and coinciding reduced to pole (RTP) maximum. Geological knowledge allowed suggesting its intrusive character and compact body form. Cluster of inverse solutions (Werner deconvolution) localized this body as initial model for forward modelling. Further iterations (23/4-D forward modelling) clarified the monzonite geometry and properties; the modelling allowed also to investigate the non-uniqueness and estimate also the confident intervals for final solution. The research consists three interconnected stages. At the detailed scale, ground magnetic data suggested three magmatic blocks of few hundred meters shifted dextral about 100 m along the Zefunut fault. Estimated accuracy for geometry of the magnetic bodies is a few tens metres. At the middle scale, quantitative gravity and magnetic interpretations provide model of the monzonite body, which is an order of magnitude more than the volume of the felsic rhyolites and granite rocks. Boundary of the whole monzonite body was estimated with accuracy as a hundred meters. As a result we suggest that the parent magma for the AIC is the monzonite, similar to the model suggested for the Timna Igneous Complex 12 km north of the AIC. The model developed can be applied to evaluate the subsurface volumes of the mafic magmatic rocks in adjacent locations. At the regional scale for exposed the Sinai and Arab Saudi Precambrian crystalline shield our approach allows to understand the apparent contradiction between geological predominantly granite composition (low magnetic rocks) and magnetic data. The aeromagnetic data show number strong

  6. Granodiorite Pluton Formation at the Mid-Cenozoic Never Summer Igneous Complex, North-Central Colorado

    NASA Astrophysics Data System (ADS)

    Jacob, K. H.; Farmer, G.

    2012-12-01

    Field observations, major- and trace-element geochemistry, and Sr and Nd isotopic data were used to assess the petrogenesis of epizonal intrusive rocks and related volcanic rocks from the ~28 Ma Never Summer igneous complex in north-central Colorado. Intrusive igneous rocks at this igneous center consist of an older granodiorite pluton (the Mt Richthofen stock, MRS) that is intruded by the granitic Mt. Cumulus stock. The latter has a uniform bulk composition equivalent to that of high silica rhyolite (~77 wt % SiO2, ɛNd(T) ~ -6). Whole rock studies of the MRS reveal that it is compositionally zoned (55-67 wt % SiO2,ɛNd(T) -0.5 to -5.7, 87Sr/86Sr(T) 0.7049 to 0.7119), with the lowest wt % SiO2 and highest ɛNd(T) occurring along the western margin of the pluton. Field observations, combined with the observed compositional variations, suggest that the pluton was originally a shallowly intruded (< 2 km), ~1 km thick sill that was vertically zoned from a mafic base to more felsic roof. The entire pluton has been tilted ~25 degrees to the west after emplacement. Given the lack of obvious wall-rock assimilation at the level of pluton emplacement, the isotopic variations in the pluton most likely reflect differences in the isotopic compositions of melts from which the pluton was assembled. Obvious field evidence exists for underplating of the developing pluton by mafic, high ɛNd (T) (>-2) melts and illustrates that mafic magmas were present in the uppermost crust and likely participated in pluton formation. The higher wt % SiO2 and lower ɛNd(T) portions of the MRS, however, could not have been derived directly from the mafic magmas in any closed system process. One option is that the MRS ultimately represents the product of mixing of >70 wt % SiO2 melts (+ crystals), analogous to the melts from which the Mt. Cumulus stock crystallized, and underplating mafic magma. This model implies that two primary magmas types, high silica rhyolite and basalt/basaltic andesite

  7. Zonation of the Newry Igneous Complex, Northern Ireland, based on geochemical and geophysical data

    NASA Astrophysics Data System (ADS)

    Anderson, P. E.; Cooper, M. R.; Stevenson, C. T.; Hastie, A. R.; Hoggett, M.; Inman, J.; Meighan, I. G.; Hurley, C.; Reavy, R. J.; Ellam, R. M.

    2016-09-01

    The Late Caledonian Newry Igneous Complex (NIC), Northern Ireland, comprises three largely granodioritic plutons, together with an intermediate-ultramafic body at its northeastern end. New whole-rock geochemical data, petrological classifications, and published data, including recent Tellus aeromagnetic and radiometric results, have been used to establish 15 distinct zones across the four bodies of the NIC. These become broadly younger to the southwest of the complex and toward the centres of individual plutons. In places, zones are defined by both current compositional data (geochemistry and petrology) and Tellus results. This is particularly clear at the eastern edge of the NIC, where a thorium-elevated airborne radiometric signature occurs alongside distinct concentrations of various elements from geochemistry. However, in the northeastern-most pluton of the NIC, a prominent ring-shaped aeromagnetic anomaly occurs independent of any observed surface compositional variation, and thus the zones in this area are defined by aeromagnetic data only. The origins of this and other aeromagnetic anomalies are as yet undetermined, although in places, these closely correspond to facies at the surface. The derived zonation for the NIC supports incremental emplacement of the complex as separate, distinct magma pulses. Each pulse is thought to have originated from the same fractionally crystallising source that periodically underwent mixing with more basic magma.

  8. Petrogenesis of the Bashisuogong bimodal igneous complex in southwest Tianshan Mountains, China: Implications for the Tarim Large Igneous Province

    NASA Astrophysics Data System (ADS)

    Ma, Yuan; Zhang, Zhaochong; Huang, He; Santosh, M.; Cheng, Zhiguo

    2016-11-01

    The Bashisuogong (BSSG) complex is located in the tectonic transition zone between South Tianshan Collisional Belt (STCB) and Tarim Block (TB). The complex is composed of a mafic unit (mainly including gabbro and diabase) and a felsic unit (mainly composed of quartz syenite and alkali granite), both of which are crosscut by several diabase and alkali granite dykes. Here we present LA-ICP-MS zircon U-Pb data which show that the two units were emplaced coevally at 276 Ma. The rocks from the two units display a wide SiO2 gap, implying a typical bimodal magmatic feature. The petrographic and geochemical evidence such as mafic microgranular enclave (MME) within the syenite, negative linear correlations between SiO2 and some major elements, and a wide range of (87Sr/86Sr)i suggest that the syenite formed via magma mixing process. The positive εNd(t) values (+ 5.42 to + 5.66 for gabbro and + 4.70 to + 5.02 for diabase) and OIB-like geochemical features of the mafic unit indicate that the parent magma was derived from asthenospheric mantle or mantle plume. The felsic unit shows higher contents of SiO2, K2O and total alkalis. Their trace element patterns are characterized by Rb, Y, Zr and Hf enrichment, and high 10,000 Ga/Al ratios, indicating an A1-type affinity. The syenite shows εNd(t) values in the range of - 0.15 to + 0.30 and zircon εHf(t) values of + 1.68 to + 5.10, whereas the alkali granite has εNd(t) values of - 2.10 to - 1.92 and εHf(t) values of - 4.10 to + 0.32. The two stage Hf isotope model ages of zircon grains in the syenite are older than 1.0 Ga, whereas those of the alkali granite are even older (> 1.3 Ga). Our results suggest that the alkali granite was generated by partial melting of a Neoproterozoic gabbroic source. Zircon grains in the A1-type felsic intrusions yield high Zr saturation temperature (728-983 °C). Although the OIB-like affinities and high temperature zircon grains of the BSSG complex suggest a genetic link with the Tarim mantle

  9. Magnetic fabrics and petrology of the Newry Igneous Complex, Northern Ireland reveals a new emplacement model

    NASA Astrophysics Data System (ADS)

    Anderson, Paul; Stevenson, Carl; Cooper, Mark; Ellam, Rob; Meighan, Ian; Hurley, Colm; Reavy, John; Inman, James; Condon, Dan; Crowley, Quentin

    2013-04-01

    The Newry Igneous Complex (NIC) is a largely granodioritic intrusion, comprising three plutons together with an intermediate-ultramafic body at its NE end. The recent Tellus survey of Northern Ireland has highlighted several geophysical anomalies within this area, including two previously unrecognised concentric aeromagnetic structures. U-Pb zircon ages and a geochemical study suggest that these features represent magmas intruded at different times, and that each pluton was emplaced through a series of inward-younging, concentric pulses. A combination of anisotropy of magnetic susceptibility (AMS) and field relations were used to investigate the emplacement of these pulses. AMS reveals strong, dominantly oblate, concentric fabrics. These suggest forceful emplacement. Field relationships indicate that the complex was intruded as steep, sheet-like pulses. Host rocks show deflection of fabrics around the NIC supporting the forceful emplacemnt model. However the amount of strain recorded in the host rocks does not fully explain the space required for intrusion. The presence of a deeply penetrating tectontic structure offers a way to transport magma and create space through a releasing bend. The releasing bend would have created some of the space for intrusion to take place initially and likely guided the ascent of magma. However, the strong fabrics present within the NIC suggest that most of the space for the intrusion was created in a forceful way. Therefore, the NIC was emplaced as a ballooning type pluton after ascent through a tectonically created conduit along a deeply penetrating fault.

  10. Mantle-derived sources of syenites from the A-type igneous suites - New approach to the provenance of alkaline silicic magmas

    NASA Astrophysics Data System (ADS)

    Litvinovsky, B. A.; Jahn, B. M.; Eyal, M.

    2015-09-01

    Granite is generally dominant in A-type igneous suites but these frequently include also alkali feldspar- and peralkaline- syenite and quartz syenite. Such syenites can provide essential information about magma sources and mode of generation of A-type silicic magma. This paper addresses the petrogenesis of syenites based on comparisons between the Mongolian-Transbaikalian Belt, Russia (MTB), and the northern Arabian-Nubian Shield (ANS) as exposed in the Sinai Peninsula, Egypt and adjacent areas of southern Israel. The syenitic rocks from MTB and ANS are characterized by high alkali content (Na2O + K2O = 10.5 to 12.5 wt.%) and are assigned to alkaline metaluminous and peralkaline granitoids. Peralkaline syenites are generally richer in Na and contain slightly less K and Ba than are metaluminous granitoids. REE abundances are similar in all types of syenites. The Eu/Eu* ratios range commonly from 0.35 to 0.65, although higher values, up to 1.15, attributed to presence of accumulated Afs and minor Pl, also occur in some plutons. The geochemical and Sr-Nd isotope characteristics of associated syenite, granite and monzogabbro from five igneous suites ( 80 samples) suggest that the main rock types, silicic and mafic, are cogenetic in each suite. Syenite magmas were produced from mantle-derived source with little, if any silicic crustal component. The generation of abundant A-type granite and syenite magmas in the young juvenile crust (ANS) argues that old continental crust is not required for generation of highly alkaline silicic magmas, as commonly advocated. The most probable source of both syenite and granite was mantle-derived K-rich shoshonitic monzogabbro. The bimodal character of the A-type suites suggests that partial melting of monzogabbro, rather than fractional crystallization of basic magma, accompanied with enrichment of a cumulate phase in the mafic units, was the dominant mode of granitoid magma formation. Granite magmas were produced in the lower crust at

  11. Subsurface Structure of the Bushveld Igneous Complex, South Africa: An Application of Geophysics

    NASA Astrophysics Data System (ADS)

    Vallejo, G.; Galindo, B. L.; Carranza, V.; Gomez, C. D.; Ortiz, K.; Castro, J. G.; Falzone, C.; Guandique, J.; Emry, E.; Webb, S. J.; Nyblade, A.

    2014-12-01

    South Africa is host to the largest single known platinum group metal supply in the world. The Bushveld Igneous Complex, spanning 300x400 kilometers, hosts hundreds of years' worth of platinum, chromite, vanadium, and other ore. Its wealth of these metals is tied directly to the large layered igneous intrusion that formed roughly 2061 million years ago. The extraction of platinum is vital to the industrial world - as these metals are widely used in the automotive industry, dental restorations, computer technology, in addition to many other applications. In collaboration with the Africa Array geophysics field school and the Penn State Summer Research Opportunities Program (SROP), we surveyed the Modikwa mine located along the border of the provinces of Mpumalanga and Limpopo in South Africa. The following techniques were applied to survey the area of interest: seismic refraction and reflection, gravity, magnetics, electrical resistivity, and electromagnetics. The data collected were used to determine the depth to bedrock and to identify potential mining hazards from dykes and faults in the bedrock. Several areas were studied and with the combination of the above-mentioned methods several possible hazards were identified. One broad, major dyke that was located in a prior aeromagnetic survey and several previously undetected, parallel, minor dykes were identified in the region. The overburden thickness was determined to be ̴4-5 meters in some regions, and as thin as several centimeters in others. This section of rock and soil lies above an area where platinum will likely be mined in the future. The removal of overburden can be accomplished by using power shovels or scrapers; while remaining material can be contained with the use of galvanized steel culverts. Additionally, a number of joints were located that may have allowed water to accumulate underground. The models created from the data permit us to estimate which hazards could be present in different parts of the

  12. Metamorphic and thermal evolution of large contact aureoles - lessons from the Bushveld Igneous Complex

    NASA Astrophysics Data System (ADS)

    Waters, D.

    2012-04-01

    Large igneous intrusions crystallise, cool, and transfer heat out into their host rocks. The thermal structure of the resulting aureole can be mapped as a series of assemblage zones and isograds, and can in principle be modelled on the assumption that heat transfer is dominantly by conduction. The local peak of contact metamorphism occurs later in time with increasing distance from the igneous contact. The importance of fluids as a metamorphic/metasomatic agent or heat transfer mechanism depends on volatile contents of magma and country rock, and on the geometry of the intrusion. Many of these features are spectacularly illustrated by the aureole beneath the mafic Rustenburg Layered Suite of the Bushveld Complex, which was emplaced at ca. 2060 Ma sub-concordantly into the shale-quartzite succession of the Pretoria Group in the Transvaal Basin. The layered suite reaches a thickness of at least 8 km, and the metamorphic aureole extends 4 km or more downwards into the "floor" of the intrusion. The great extent and relative absence of deformation make this a remarkable natural laboratory for studying the fundamental processes of metamorphism. In quantifying the thermal history, however, a number of second-order factors need to be taken into account. The first relates to the markedly different thermal properties of the major quartzite and shale units, and the second to the importance of endothermic metamorphic reactions in shale units relative to the quartzites. Further insights into metamorphic processes arise from the exquisite detail of poikiloblast growth microstructures preserved in graphite-poor metapelites of the Timeball Hill and Silverton Formations, 2.5 to 3.5 km beneath the igneous contact. These allow a detailed reconstruction of the time sequence of mineral growth and replacement, revealing a marked overlap of the growth intervals of porphyroblastic staurolite, cordierite, biotite, garnet and andalusite at the expense of muscovite, chlorite and chloritoid

  13. The Emplacement of the Newry Igneous Complex, Northern Ireland, from magnetic fabrics and strain

    NASA Astrophysics Data System (ADS)

    Stevenson, C.; Anderson, P.; Cooper, M.; Ellam, R. M.; Reavy, J.; Condon, D. J.; Crowley, Q.

    2013-05-01

    The Newry Igneous Complex (NIC) is a largely granodioritic intrusion, comprising three plutons together with an intermediate-ultramafic body at its NE end. The recent Tellus survey of Northern Ireland has highlighted several geophysical anomalies within this area, including two previously unrecognised concentric aeromagnetic structures. U-Pb zircon ages and a geochemical study suggest that these features represent magmas intruded at different times, and that each pluton was emplaced through a series of inward-younging, concentric pulses. A combination of anisotropy of magnetic susceptibility (AMS) and field relations were used to investigate the emplacement of these pulses. AMS reveals strong, dominantly oblate, concentric fabrics. These suggest forceful emplacement. In detail magnetic anisotropy values are highest near the boundary of internal pulses, suggesting that AMS is recording variations in magmatic strain consistent with a pulsed emplacement in unique detail. Our model for the NIC is that it was emplaced as a ballooning type pluton after ascent through a tectonically created conduit along a deeply penetrating fault.

  14. Is the West Karmøy complex igneous or metasedimentary?

    NASA Astrophysics Data System (ADS)

    Rodgers, John

    1994-03-01

    The island of Karmøy in southwestern Norway is famous among geologists for the Ophiolite, one of the first ophiolites to be recognized and described in the Scandinavian Caledonides. Much of the island is underlain by the West Karmøy Complex, presently interpreted as an igneous complex that intrudes the Karmøy Ophiolite. There is a striking resemblance of some rocks of the Complex with the Sykesville "granite" of Maryland, which was shown by Cloos and by Hopson (1964) to be a metadiamictite. After local examination of the rocks and after comparison with the 1980 report of Ledru, the conclusion was drawn that — except for the Risdal granodiorite, pegmatite and aplite dikes — the Complex is a metasedimentary, compositionally variable succession of meta-arkose (the "quartz-augen gneiss"—Ledru's Diorite quartzique et Granodiorite du nord) and metadiamictite (his various inclusion-rich "granite" units). Both units were derived by erosion from advancing thrust sheets, including the Karmøy Ophiolite, which then overrode the sedimentary succession. The high modal quartz and normative corundum contents of the "granitic" rocks resemble those of the Sykesville and favor a metasedimentary origin; the chemistry is also similar and rather far from a granite minimum melt, though certain mixtures of quartz-sandy matrix and mafic blocks may have melted locally while being overridden by the Ophiolite. Reports that quartz diorite of the West Karmøy Complex intrudes metagabbro of the Karmøy Ophiolite could not be confirmed, although trondhjemite dikes belonging to the Ophiolite do intrude the metagabbro; the contact of the Ophiolite with the Complex was faulted wherever observed. As recognized by almost all observers, both Ophiolite and Complex are overlain unconformably by Upper Ordovician sediments of the Skudeneset Group, which was later deformed and metamorphosed in the greenschist facies; at least a great part of the fault separating the Karmøy Ophiolite and the West

  15. Thermobarometric studies on the Levack Gneisses: Footwall rocks to the Sudbury Igneous Complex

    NASA Technical Reports Server (NTRS)

    James, R. S.; Peredery, W.; Sweeny, J. M.

    1992-01-01

    Granulite and amphibolite facies gneisses and migmatites of the Levack Gneiss Complex occupy a zone up to 8 km wide around the northern part of the Sudbury Igneous Complex (SIC). Orthopyroxene- and garnet-bearing tonalitic and semipelitic assemblages of granulite facies grade occur within 3 km of the SIC together with lenses of mafic and pyroxenitic rock compositions normally represented by an amphibole +/- cpx-rich assemblage; amphibolite facies assemblages dominate elsewhere in this terrain. These 2.711-Ga gneisses were introduced by (1) the Cartier Granite Batholith during late Archaean to early Proterozoic time and (2) the SIC, at 1.85 Ga, which produced a contact aureole 1-1.5 km wide in which pyroxene hornfelses are common within 200-300 m of the contact. A suite of 12 samples including both the opx-gt and amphibole-rich rock compositions have been studied. Garnets in the semipelitic gneisses are variably replaced by a plg-bio assemblage. Thermobarometric calculations using a variety of barometers and thermometers reported in the literature suggest that the granulite facies assemblages formed at depths in the 21-28 km range (6-8 kbar). Textures and mineral chemistry in the garnet-bearing semipelitic rocks indicate that this terrain underwent a second metamorphic event during uplift to depth in the 5-11 km range (2-3 kbar) and at temperatures as low as 500-550 C. This latter event is distinct from thermal recrystallization caused by the emplacement of the SIC; it probably represents metamorphism attributable to intrusion of the Cartier Granite Batholith. These data allow two interpretations for the crustal uplift of the Levack Gneisses: (1) The gneisses were tectonically uplifted prior to the Sudbury Event (due to intrusion of the Cartier Batholith); or (2) the gneisses were raised to epizonal levels as a result of meteorite impact at 1.85 Ga.

  16. The Paleoproterozoic Singo granite in south-central Uganda revealed as a nested igneous ring complex using geophysical data

    NASA Astrophysics Data System (ADS)

    Abdelsalam, Mohamed G.; Katumwehe, Andrew B.; Atekwana, Estella A.; Le Pera, Alan K.; Achang, Mercy

    2016-04-01

    We used high-resolution airborne magnetic and radiometric data and satellite gravity data to investigate the form of occurrence of the Paleoproterozoic Singo granite in west-central Uganda. This granitic body covers an area of ∼700 km2, intrudes Paleoproterozoic crystalline rocks and overlain by Paleoproterozoic-Mesoproterozoic sedimentary rocks, both of which belong to the Rwenzori terrane, and it is host to hydrothermally-formed economic minerals such as gold and tungsten. Our analysis provided unprecedented geometrical details of the granitic body and revealed the following: (1) the margins of the Singo granite are characterized by a higher magnetic signature compared to the interior of the granitic body as well as the surroundings. These anomalies are apparent in both the total magnetic field and horizontal derivative images and define eight overlapping ring features. (2) the depth continuation of these magnetic anomalies define outward but steeply-dipping features as indicated by the tilt images extracted from the airborne magnetic data. This is further supported by forward modeling of the magnetic and gravity data. (3) the Singo granite is characterized by relatively high and evenly-distributed equivalent concentration of Uranium (eU) and Thorium (eTh) compared to the surroundings and this is apparent in the Potassium (K)-eTh-eU radiometric ternary image. (4) the granitic body is defined by a gravity low anomaly that persisted to a depth of three km as shown by the Bouguer anomaly image and its five km upward continuation. We used these observations to identify this granitic body as a nested igneous ring complex and we refer to it as the Singo Igneous Ring Complex (SIRC). We further interpreted the eight ring structures as individual igneous ring complexes aligned in an E-W and NE-SW direction and these were developed due to repeated calderas collapse. Additionally, we interpreted the ring-shaped magnetic anomalies as due to hydrothermally-altered margins

  17. A melt inclusion study of the Sudbury Igneous Complex (Ontario, Canada): preliminary results

    NASA Astrophysics Data System (ADS)

    Watts, Kathleen; Hanley, Jacob; Kontak, Daniel; Ames, Doreen

    2013-04-01

    The 1.85 Ga Sudbury Igneous Complex (SIC), Ontario, Canada, is an intrusive complex representing the crystallized melt sheet that formed within a large impact crater. The SIC has been extensively studied due to its rich endowment in magmatic sulfide ores (Ni-Cu-PGEs). The nature and origin of the SIC melt sheet and its subsequent evolution still remain controversial. In this study, analyses of primary melt inclusions hosted in cumulus apatite within three mafic units of the SIC (gabbro, norite and sublayer quartz diorite) are used to decipher the thermometric and chemical characteristics of the evolving melt sheet as it crystallized. Apatite-hosted melt inclusions commonly display a negative crystal shape, occur parallel to the c-axis, and often occur within a central growth zone, which suggest a primary origin. The compositions of coeval (co-entrapped) melt inclusions are distinct and may represent either the products of immiscibility (low or high temperature field; c.f. the Skaergaard Intrusion: Jakobsen et al., Geology, 2005), or a product of early, high-temperature, impact-generated emulsification (prior to and independent of crystallization of the melt sheet). The compositions of homogenized (1100-1200oC for 3 hrs) melt inclusions, determined by SEM-EDS and EMP analyses of opened, homogenized melt inclusions, equate to two distinct compositions: (1) Type-I are SiO2-rich, ranging from tonalitic to granodioritic in composition (60-70 wt% SiO2, up to 11 wt% FeO); and (2) Type-II are Fe-rich with syenogabbroic to essexitic to alkali gabbroic compositions (27-49 wt% SiO2, 16-44 wt% FeO). Trace element data, obtained by LA-ICPMS analyses of single inclusions and surrounding host apatite, are used to infer D values between apatite and the two melt types, and between the coexisting melt types. Apparent Dap-melt values for both Type-I and Type-II inclusions show that the REE, Sr, and Y are compatible in apatite, and As is weakly compatible or incompatible in apatite

  18. Tilting, burial, and uplift of the Guadalupe Igneous Complex, Sierra Nevada, California

    USGS Publications Warehouse

    Haeussler, Peter J.; Paterson, Scott R.

    1993-01-01

    It is often incorrectly assumed that plutons have a relatively uneventful structural history after emplacement. The 151 Ma Guadalupe Igneous Complex (GIC) in the Foothills Terrane, California, was involved in three post-emplacement events: (1) ∼30° of southwestside-up tilting during ductile regional faulting and contraction, (2) burial of the pluton from ∼4 to 12 km during crustal thickening of the wall rocks, and (3) uplift with only minor tilting in the Late Cretaceous. Tilting of the pluton is indicated by (1) southwest to northeast gradational changes from layered gabbros and diorites to granites and granophyres; (2) northeastward dips of layering in gabbro, internal contacts, and bedding of overlying coeval(?) volcanic rocks; (3) northeastward decrease in wall-rock metamorphic grade; and (4) paleomagnetic data from 14 localities across the pluton. We argue that tilting occurred between 146-135 Ma during southwest-northeast-directed regional contraction. This contraction is indicated by widespread folds and cleavages and by reverse motion on the Bear Mountains fault zone (BMFZ), a large northeast-dipping shear zone that bounds the GIC on its southwest side. Burial of the GIC, which overlapped in time but outlasted tilting, is suggested by (1) post-emplacement contractional faulting, folding, and cleavage development; (2) analyses of strains associated with widespread cleavage that indicate vertical thickening of ∼100% and (3) microstructural and mineral assemblage data that indicate shallow emplacement of the GIC, in contrast to mineral assemblage and limited geobarometric data from adjacent 120-110 Ma plutons that indicate moderate emplacement levels. Late Cretaceous uplift is indicated by 95-75 Ma sedimentary rocks that unconformably overlie the 120-110 Ma plutons.This geologic history is interesting for several reasons. First, although the GIC participated in extensive post-emplacement deformation, it lacks internal structural evidence of these events

  19. Electrochemical effects of magmatic crystallisation: cyclic units of the Bushveld Igneous Complex

    NASA Astrophysics Data System (ADS)

    Veksler, Ilya V.; Reid, David L.; Dulski, Peter; Keiding, Jakob K.; Trumbull, Robert B.

    2013-04-01

    The Upper Critical Zone (UCZ) of the Bushveld Igneous Complex displays spectacular layering in the form of cyclic units comprising a basal chromitite layer overlain by a sequence of silicate cumulates in the order, from the bottom to the top, pyroxentite-norite-anorthosite. Electron microprobe and laser ablation ICP-MS analyses of chromite and silicate cumulate minerals in the cyclic units between the UG2 chromitite and the Merensky reef revealed variations in major and trace element compositions that are difficult to reconcile with existing models of cumulate mineral-melt evolution. The anomalies in mineral chemistry are best developed at sharp contacts of chromitites with adjacent anorthosite and pyroxenitic cumulates. At the contacts, major element characteristics of chromite composition change abruptly from high and stable Mg/(Mg+Fe2+) and Fe2+/Fe3+ typical for cumulus chromitites to variable and generally low values in chromite crystals disseminated in silicate cumulates. Chromites from different types of cumulates also differ in Sc, V, Ni and Zn contents. The abrupt changes in chromite composition mark the contacts regardless of the thickness of the chromitite layer and estimated mass proportions of chromite to intercumulus liquid. Chemical variations, which defy a simple explanation, are also observed in plagioclase. In addition to previously revealed inconsistency between chemical trends of cumulus plagioclase and orthopyroxene in the UCZ cyclic units our study demonstrates that intercumulus, poikilitic plagioclase cementing chromitite layers has anomalously low Li, K, Rb concentrations and K/La values. Summarising previous studies and the new trace element data we propose a model of post-cumulus re-crystallisation leading to consolidation of a modally layered crystal-liquid mush into a sequence of nearly monomineral layers of chromitites, pyroxenites and anorthosites, which defines the cyclic units. The crucial element of the model is the establishment of

  20. A review of scientific literature examining the mining history, geology, mineralogy, and amphibole asbestos health effects of the Rainy Creek igneous complex, Libby, Montana, USA.

    PubMed

    Bandli, Bryan R; Gunter, Mickey E

    2006-11-01

    This article reviews the past 90 yr of scientific research directed on multiple aspects of the unique geology and environmental health issues surrounding the vermiculite deposit found at Libby, MT. Hydrothermal alteration and extensive weathering of the ultramafic units resulted in the formation of a rich deposit of vermiculite that was mined for 67 yr and used in numerous consumer products in its expanded form. Later intrusions of alkaline units caused hydrothermal alteration of the pyroxenes, resulting in formation of amphiboles. Some of these amphiboles occur in the asbestiform habit and have been associated with pulmonary disease in former miners and mill workers. Identification of these amphibole asbestos minerals has received little attention in the past, but recent work shows that the majority of the amphibole mineral species present may not be any of the amphibole species currently regulated by government agencies. Epidemiological studies on former miners have, nevertheless, shown that the amphibole asbestos from the Rainy Creek igneous complex is harmful; also, a recent study by the Agency for Toxic Substances and Disease Registry shows that residents of Libby who had not been employed in the vermiculite mining or milling operations also appear to have developed asbestos-related pulmonary diseases at a higher rate than the general public elsewhere. Since November 1999, the U.S. Environmental Protection Agency has been involved in the cleanup of asbestos-contaminated sites in and around Libby associated with the mining and processing of vermiculite.

  1. Petrochemistry and hydrothermal alteration within the Tyrone Igneous Complex, Northern Ireland: implications for VMS mineralization in the British and Irish Caledonides

    NASA Astrophysics Data System (ADS)

    Hollis, Steven P.; Roberts, Stephen; Earls, Garth; Herrington, Richard; Cooper, Mark R.; Piercey, Stephen J.; Archibald, Sandy M.; Moloney, Martin

    2014-06-01

    Although volcanogenic massive sulfide (VMS) deposits can form within a wide variety of rift-related tectonic environments, most are preserved within suprasubduction affinity crust related to ocean closure. In stark contrast to the VMS-rich Appalachian sector of the Grampian-Taconic orogeny, VMS mineralization is rare in the peri-Laurentian British and Irish Caledonides. Economic peri-Gondwanan affinity deposits are limited to Avoca and Parys Mountain. The Tyrone Igneous Complex of Northern Ireland represents a ca. 484-464 Ma peri-Laurentian affinity arc-ophiolite complex and a possible broad correlative of the Buchans-Robert's Arm belt of Newfoundland, host to some of the most metal-rich VMS deposits globally. Stratigraphic horizons prospective for VMS mineralization in the Tyrone Igneous Complex are associated with rift-related magmatism, hydrothermal alteration, synvolcanic faults, and high-level subvolcanic intrusions (gabbro, diorite, and/or tonalite). Locally intense hydrothermal alteration is characterized by Na-depletion, elevated SiO2, MgO, Ba/Sr, Bi, Sb, chlorite-carbonate-pyrite alteration index (CCPI) and Hashimoto alteration index (AI) values. Rift-related mafic lavas typically occur in the hanging wall sequences to base and precious metal mineralization, closely associated with ironstones and/or argillaceous sedimentary rocks representing low temperature hydrothermal venting and volcanic quiescence. In the ca. 475 Ma pre-collisional, calc-alkaline lower Tyrone Volcanic Group rift-related magmatism is characterized by abundant non-arc type Fe-Ti-rich eMORB, island-arc tholeiite, and low-Zr tholeiitic rhyolite breccias. These petrochemical characteristics are typical of units associated with VMS mineralization in bimodal mafic, primitive post-Archean arc terranes. Following arc-accretion at ca. 470 Ma, late rifting in the ensialic upper Tyrone Volcanic Group is dominated by OIB-like, subalkaline to alkali basalt and A-type, high-Zr rhyolites. These units

  2. Mercury(II) Penicillamine Complex Formation in Alkaline Aqueous Solution

    SciTech Connect

    Leung, B.O.; Jalilehvand, F.; Mah, V.

    2009-06-01

    The complex formation between mercury(II) and penicillamine (H{sub 2}Pen = 3,3'-dimethyl cysteine) in alkaline aqueous solutions (pH {approx}2) has been investigated with extended X-ray absorption fine structure (EXAFS) and {sup 199}Hg NMR spectroscopy. By varying the penicillamine concentration (C{sub H{sub 2}Pen} = 0.2--1.25 M) in {approx}0.1 M Hg(II) solutions, two coexisting major species [Hg(Pen){sub 2}]{sup 2-} and [Hg(Pen){sub 3}]{sub 4-} were characterized with mean Hg-S bond distances 2.34(2) and 2.44(2) {angstrom}, respectively. The [Hg(Pen){sub 2}]{sup 2-} complex with two deprotonated penicillamine ligands forms an almost linear S-Hg-S entity with two weak chelating Hg-N interactions at the mean Hg-N distance 2.52(2) {angstrom}. The same type of coordination is also found for the corresponding [Hg(Cys){sub 2}]{sup 2-} complex in alkaline aqueous solution with the mean bond distances Hg-S 2.34(2) {angstrom} and Hg-N 2.56(2) {angstrom}. The relative amounts of the [Hg(Pen){sub 2}]{sup 2-} and [Hg(Pen){sub 3}]{sup 4-} complexes were estimated by fitting linear combinations of the EXAFS oscillations to the experimental spectra. Also their {sup 199}Hg NMR chemical shifts were used to evaluate the complex formation, showing that the [Hg(Pen){sub 3}]{sup 4-} complex dominates already at moderate excess of the free ligand ([Pen{sup 2-}] > {approx} 0.1 M).

  3. The influence of complexing pharmaceutical compositions on alkaline phosphatase

    NASA Astrophysics Data System (ADS)

    Atyaksheva, L. F.; Chukhrai, E. S.; Stepina, N. D.; Novikova, N. N.; Yur'eva, E. A.

    2011-06-01

    It is established that the pharmaceutical compositions xydiphon, medifon, succimer, and EDTA, which are used as complexing agents for accelerating the excretion of heavy metals from human organism, at certain concentrations inhibit enzyme alkaline phosphatase (AP). It is concluded that xydiphon and EDTA have a noticeable effect on AP activity at concentrations over 0.01 mM; medifon and succimer, at concentrations of over 0.3-0.5 mM. The enzyme's inhibition constants and type of inhibition are determined. Xydiphon is found to manifest the highest affinity to AP ( K I = 0.35 mM). It is shown by kinetic analysis that dissociative chemoinactivation of the enzyme takes place under the action of complexing agents. The corresponding kinetic parameters are calculated.

  4. Middle Jurassic oceanic island igneous rocks of the Raohe accretionary complex, northeastern China: Petrogenesis and tectonic implications

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Hui; Ge, Wen-Chun; Yang, Hao; Zhang, Yan-Long; Bi, Jun-Hui; Tian, De-Xin; Xu, Wen-Liang

    2015-11-01

    Whole-rock major and trace element, and Sr, Nd, and Hf isotopic data, together with zircon U-Pb ages and in situ zircon Hf isotopes, are reported for Middle Jurassic igneous rocks of the Raohe accretionary complex, northeastern China, to investigate their petrogenesis and tectonic implications. The igneous rocks consist of pillow basalt, pyroxenite, gabbro, plagioclasite, and plagiogranite. The zircons from one plagioclasite and one plagiogranite are euhedral-subhedral and display fine-scale oscillatory growth zoning, indicating a magmatic origin. Zircon U-Pb dating gives an emplacement age of 169-167 Ma. The basalts are associated with late Paleozoic to middle Mesozoic sediments typical of ocean plate stratigraphy; i.e., limestone, bedded chert, and siliceous shale. The basalts, which show geochemical features similar to those of oceanic island basalts (OIBs), are enriched in TiO2, light rare earth elements (LREEs) (average: La/Smn = 2.12), and Nb (average: Zr/Nb = 12.24), and are characterized by positive Nb anomalies (averages: Nb/Thpm = 1.46, Nb/Lapm = 1.31). The rocks are depleted in heavy rare earth elements (HREEs) (average: Gd/Ybn = 2.03) and exhibit high εNd(t) (+8.2 to +8.3) and εHf(t) (+9.0 to +9.1) values. The geochemical features indicate the Jurassic OIB-like basalts were derived by a low degree of partial melting (<5%) of peridotite in the garnet stability field. The intermediate-mafic intrusive rocks show typical OIB affinities and are geochemically similar to the basalts. Most of the intermediate-mafic intrusive rocks are enriched in LREEs and Nb, depleted in HREEs, and show low Zr/Nb ratios and high εNd(t) (+7.2 to +8.2) and εHf(t) (+8.8 to +10.3) values, indicating they were derived from a common source and are the products of fractional crystallization of the OIB-like basalts. All of the igneous rocks are likely fragments of oceanic islands/seamounts. The identification of OIB-like basalts and associated intermediate-mafic intrusive rocks

  5. Cu(II) complex formation with xylitol in alkaline solutions.

    PubMed

    Norkus, Eugenijus; Vaiciūniene, Jūrate; Vuorinen, Tapani; Gaidamauskas, Ernestas; Reklaitis, Jonas; Jääskeläinen, Anna-Stiina; Crans, Debbie C

    2004-02-25

    The formation of four Cu(II)-xylitol complexes was observed in aqueous alkaline solutions (11.0< or =pH< or =14.0, I=1.0, 20 degrees C) by means of direct current polarography and VIS spectrophotometry. Mononuclear hydroxy complexes, CuXyl(OH)- (log beta=17.7 +/- 0.5), CuXyl(OH)2(2-) (log beta=20.2 +/- 0.3) and CuXyl2(OH)2(4-) (log beta=22.4 +/- 0.3), are formed at high ligand-to-metal ratios (L:M> or =10), whereas dinuclear complex Cu2Xyl (log beta=29.2 +/- 0.3) is the predominant species at low ligand-to-metal ratio (L:M=0.5). Diffusion coefficients and molar absorptivities of the complex species were determined. pH variable 13C NMR suggested that pKa values of xylitol are rather similar and equal to 13.8 +/- 0.2, 13.9 +/- 0.1 and 13.9 +/- 0.2 for OH-groups adjacent to (C-1,C-5), (C-3) and (C-2,C-4) carbon atoms, respectively.

  6. Syn- and post-orogenic alkaline magmatism in a continental arc: Along-strike variations in the composition, source, and timing of igneous activity in the Ross Orogen, Antarctica

    NASA Astrophysics Data System (ADS)

    Hagen-Peter, G.; Cottle, J. M.

    2013-12-01

    Neoproterozoic-Paleozoic convergence and subduction along the margin of East Gondwana (Australia, New Zealand, Antarctica) resulted in a belt of deformed and metamorphosed sedimentary rocks and batholith-scale igneous intrusions comparable in size to the present day Andes. Mid-crustal levels of this belt, known as the Ross Orogen in Antarctica, are exposed in the basement of the Cenozoic Transantarctic Mountains, providing snapshots of the intrusive magma system of a major continental arc. Whole rock major- and trace-element geochemistry, Hf isotopes in zircon, and U-Pb geochronology have identified along-strike variations in the composition, source, and timing of magmatism along ~200 km of the southern Victoria Land segment of the orogen. There is an apparent younging of the igneous activity from south to north. New U-Pb ages for intrusive rocks from the Koettlitz Glacier Alkaline Province (KGAP) reveal that igneous activity spanned ca. 565-500 Ma (~30 m.y. longer than previously recognized), while immediately to the north in the Dry Valleys area most igneous activity was confined to a relatively short period (ca. 515-495 Ma). Alkaline and subalkaline igneous rocks occur in both the Dry Valleys area and the KGAP, but alkaline rocks in the Dry Valleys are restricted to the latest phase of magmatism. Na-alkaline rocks in the KGAP, including nepheline syenites, carbonatites, and A-type granites, range in age from ca. 545-500 Ma and overlap in age with more typical subduction/collision-related I- and S-type granites elsewhere in southern Victoria Land. Strong enrichments in the LILE and LREE and high LILE/HFSE and LREE/HREE of samples from the KGAP reveal a source enriched in aqueous-mobile elements, potentially a strongly metasomatized mantle wedge beneath the arc. In the Dry Valleys area, rocks with alkali-calcic composition constitute only the youngest intrusions (505-495 Ma), apparently reflecting a shift to post-orogenic magmatism. Zircons from Dry Valleys

  7. Crystal mat-formation as an igneous layering-forming process: Textural and geochemical evidence from the 'lower layered' nepheline syenite sequence of the Ilímaussaq complex, South Greenland

    NASA Astrophysics Data System (ADS)

    Lindhuber, Matthias J.; Marks, Michael A. W.; Bons, Paul D.; Wenzel, Thomas; Markl, Gregor

    2015-05-01

    The lower layered nepheline syenite sequence (kakortokites) of the Mesoproterozoic alkaline to peralkaline Ilímaussaq complex, South Greenland shows spectacular rhythmic meter-scale igneous layering. The 29 exposed units have sharp contacts against each other and each of these units consists of three modally graded layers dominated by arfvedsonitic amphibole, eudialyte-group minerals, and alkali feldspar, respectively. This study uses field observations on changes in mineral orientation, recurrent mineral textures, compositional data from eudialyte-group minerals and amphibole, and settling rate calculations based on a modified Stokes' equation to explain the igneous layering of the kakortokites. We propose that the three major cumulus minerals (amphibole, eudialyte s.l., and alkali feldspar) were separated from each other by density contrasts, resulting in modally graded layers within each unit. The densest of these three minerals (amphibole) formed crystal mats within the cooling magma body. These crystal mats acted as barriers that inhibited large-scale vertical migration of melts and crystals with increasing effectiveness over time. The sub-volumes of magma captured in between the crystal mats evolved largely as geochemically independent sub-systems, as indicated by the observed trends in mineral composition.

  8. Anatomy of a deep crustal volcanic conduit system; The Reinfjord Ultramafic Complex, Seiland Igneous Province, Northern Norway

    NASA Astrophysics Data System (ADS)

    Grant, Thomas B.; Larsen, Rune B.; Anker-Rasch, Lars; Grannes, Kim Rune; Iljina, Markku; McEnroe, Suzanne; Nikolaisen, Even; Schanche, Mona; Øen, Endre

    2016-05-01

    The Reinfjord Ultramafic Complex, Seiland Igneous Province represents a lower crustal magma chamber (25-30 km depth) that likely records a deep conduit system for mantle derived melts ascending through the continental crust. It consists of cumulates of dunite, wehrlite, olivine clinopyroxene as well as subordinate lherzolite and websterites, intruded into gabbro-norite and metasediment gneisses. Field, petrographic and geochemical data show that the intrusion developed through fractional crystallization and interactions between new batches of magma and partially solidified cumulates. This resulted in a 'reverse fractionation sequence' whereby cumulates became progressively more MgO and olivine rich with time. Contamination by partial melting of the gabbro-norite is evident in the marginal zones, but is limited in the central parts of the intrusion. Interrupted crystallization sequences of olivine → olivine + clinopyroxene and the absence of significant amounts of more evolved melts, suggests that large volumes of melt passed through the system to shallower levels in the crust leaving behind the cumulate sequences observed at Reinfjord. Therefore, the Reinfjord Ultramafic Complex represents a deep crustal conduit system, through which mantle derived melts passed. The parent melts are likely to have formed from partial melting of mantle with residual garnet and clinopyroxene.

  9. Studying Spectral Variability of an Igneous Stratified Complex as a Tool to Map Lunar Highlands

    NASA Astrophysics Data System (ADS)

    Carli, C.; Sgavetti, M.; Capaccioni, F.; Serventi, G.

    2012-07-01

    Moon Mineralogy Mapper data have revealed different portion of magmatic chambers or separate plutons. We analysed Stillwater Complex (SWC) rock suite. Spectral signatures and spectral parameters could help to interpret the new spectral lunar data.

  10. Assessment of the natural radioactivity and its radiological hazards in Shewa-Shahbaz Garhi igneous complex, Peshawar Plain, NW Pakistan.

    PubMed

    Ali, Amanat; Orfi, S D; Qureshi, A A

    2002-01-01

    Forty-two representative rock samples used for construction purpose were collected from the quarries and outcrops of the rock units forming the Shewa-Shahbaz Garhi igneous complex, North-West Pakistan. Radioactivity of terrestrial radionuclides (238U, 232Th, and 40K) was measured in these samples using gamma ray spectrometry system with an HPGe detector. The samples showed fairly high mean concentrations of 51 +/- 16 Bq kg(-1) of 238U, 70 +/- 20 Bq kg(-1) of 232Th and 1,272 +/- 367 Bq kg(-1) of 40K. Mean absorbed gamma dose rate in air of 119 +/- 29 nGy h(-1) was found. Assessment of radiological hazards was made by calculating radium equivalent activities with external and internal hazard indices. The calculations showed radium equivalent activity ranging from 52 to 346 Bq kg(-1). External and internal hazard indices ranging from 0.14 to 0.94 and 0.17 to 1.1, respectively, were found.

  11. The Hlagothi Complex: The identification of fragments from a Mesoarchaean large igneous province on the Kaapvaal Craton

    NASA Astrophysics Data System (ADS)

    Gumsley, A. P.; de Kock, M. O.; Rajesh, H. M.; Knoper, M. W.; Söderlund, U.; Ernst, R. E.

    2013-08-01

    In this paper, we present geochronological, geochemical and palaeomagnetic results from the Hlagothi Complex and a NW-trending dolerite dyke swarm on the southeastern region of the Kaapvaal Craton in northern KwaZulu-Natal, South Africa. The Hlagothi Complex consists of layered sills of meta-peridotite, pyroxenite and gabbro intruding into the Pongola Supergroup. U-Pb baddeleyite ages on the Hlagothi Complex and a NW-trending dyke of 2866 ± 2 Ma and 2874 ± 2 Ma, respectively, reveal a ca. 2.87 Ga magmatic event on the southeastern Kaapvaal Craton. The geochemical signature of the Hlagothi Complex recognises two discrete groupings, with a magmatic source that is chemically distinct from those of the older rift-related Nsuze and Dominion groups. Additional units on the Kaapvaal Craton can be linked with this new ‘Hlagothi' event based on spatial and temporal association, and geochemistry: 1) the Thole Complex, 2) parts of the Usushwana Complex, and 3) flood basalts within the Mozaan Group and Central Rand Group. The association between all these units suggests a previously unrecognised large igneous province in the southeastern Kaapvaal Craton. Our palaeomagnetic data identifies a possible primary magnetisation within the least-altered lithologies of the Hlagothi Complex (with a virtual geographic pole at 23.4°N, 53.4°E, dp = 8.2° and dm = 11.8°). The bulk of samples however, displayed two episodes of remagnetisation. These are likely to be associated with 2.85 to 2.75 Ga aged granitoids across the southeastern Kaapvaal Craton, and tectonic activity in the nearby Meso- to Neoproterozoic Namaqua-Natal mobile belt. A short-lived (≤ 8 Ma) mantle plume is proposed to have caused the ca. 2.87 Ga magmatism, and also may well have controlled sedimentation within the Pongola-Witwatersrand basin. Volcanism during uplift would have been fed through a series of feeder dykes and sills, of which the Hlagothi Complex and NW-trending dykes are part of.

  12. Radiological Mapping of the Alkaline Intrusive Complex of Jombo, South Coastal Kenya by In-Situ Gamma-Ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Kaniu, Ian; Darby, Iain G.; Kalambuka Angeyo, Hudson

    2016-04-01

    Carbonatites and alkaline intrusive complexes are rich in a variety of mineral deposits such as rare earth elements (REEs), including Nb, Zr and Mn. These are often associated with U and Th bearing minerals, including monazite, samarskite and pyrochlore. Mining waste resulting from mineral processing activities can be highly radioactive and therefore poses a risk to human health and environment. The Jombo complex located in Kenya's south coastal region is potentially one of the richest sources of Nb and REEs in the world. It consists of the main intrusion at Jombo hill, three associated satellite intrusions at Mrima, Kiruku and Nguluku hills, and several dykes. The complex is highly heterogeneous with regard to its geological formation as it is characterized by alkaline igneous rocks and carbonatites which also influence its radio-ecological dynamics. In-situ gamma spectrometry offers a low-cost, rapid and spatially representative radioactivity estimate across a range of landscapes compared to conventional radiometric techniques. In this work, a wide ranging radiological survey was conducted in the Jombo complex as follow up on previous studies[1,2], to determine radiation exposure levels and source distributions, and perform radiological risk assessments. The in-situ measurements were carried out using a 2.0 l NaI(Tl) PGIS-2 portable detector from Pico Envirotec Inc integrated with GPS, deployed for ground (back-pack) and vehicular gamma-ray spectrometry. Preliminary results of radiological distribution and mapping will be presented. [1] Patel, J. P. (1991). Discovery and Innovation, 3(3): 31-35. [2] Kebwaro, J. M. et. al. (2011). J. Phys. Sci., 6(13): 3105-3110.

  13. Geophysical analysis of the Alpha-Mendeleev ridge complex: Characterization of the High Arctic Large Igneous Province

    NASA Astrophysics Data System (ADS)

    Oakey, G. N.; Saltus, R. W.

    2016-11-01

    The Alpha-Mendeleev ridge complex is a first-order physiographic and geological feature of the Arctic Amerasia Basin. High amplitude "chaotic" magnetic anomalies (the High Arctic Magnetic High Domain or HAMH) are associated with the complex and extend beyond the bathymetric high beneath the sediment cover of the adjacent Canada and Makarov-Podvodnikov basins. Residual marine Bouguer gravity anomalies over the ridge complex have low amplitudes implying that the structure has minimal lateral density variability. A closed pseudogravity (magnetic potential) contour around the ridge complex quantifies the aerial extent of the HAMH at 1.3 × 106 km2. We present 2D gravity/magnetic models for transects across the Alpha Ridge portion of the complex constrained with recently acquired seismic reflection and refraction data. The crustal structure is modeled with a simple three-layer geometry. Large induced and remanent magnetization components were required to fit the observed magnetic anomalies. Density values for the models were based on available seismic refraction P-wave velocities. The 3000 kg/m3 lower crustal layer is interpreted as a composite of the original crustal protolith and deep (ultramafic) plutonic intrusions related to a plume sourced (High Arctic) LIP. The 2900 kg/m3 mid-crustal and 2600 kg/m3 upper-crustal layers are interpreted as the combined effect of sills, dikes, and flows. Volumetric estimates of the volcanic composition include (at least) 6 × 106 km3 for the mid- and upper-crust and between 13 × 106 and 17 × 106 km3 within the lower crust - for a total of 20 × 106 km3. We compare the magnetic structure, pseudogravity, and volumetric estimates for the HAMH portion of the HALIP with global large igneous province analogs and discuss implications for Arctic tectonics. Our results show that the closest analog to the HAMH/HALIP is the Kerguelen Plateau, which is considered a continental plateau intensively modified by plume-related volcanism.

  14. Assembly of a zoned volcanic magma chamber from multiple magma batches: The Cerberean Cauldron, Marysville Igneous Complex, Australia

    NASA Astrophysics Data System (ADS)

    Clemens, J. D.; Birch, W. D.

    2012-12-01

    The Late Devonian (374 Ma) Cerberean Cauldron forms the northern part of the Marysville Igneous Complex, in Central Victoria, Australia, filled with around 900 km3 of intra-caldera ignimbrites. The basal volcanic formation is the rhyolitic high-Al Rubicon Ignimbrite, overlain by a larger volume of crystal-rich rhyolitic low-Al Rubicon Ignimbrite, which grades upward into the voluminous, rhyodacitic Lake Mountain Ignimbrite. The rocks are S-type in character, with initial 87Sr/86Sr around 0.709 to 0.710 and ɛNdt varying from - 4.7 to - 6.0, suggesting metagreywacke protoliths. The chemistry of the volcanic rocks is incompatible with formation by a differentiation mechanism. Experimentally determined phase relations of a low-Al Rubicon Ignimbrite and a Lake Mountain Ignimbrite show that early crystallisation of the Lake Mountain magma began at > 450 MPa and at > 875 °C (possibly up to 940 °C), with an initial magma H2O content of 4.1 to 5.3 wt.%. In the pre-eruption magma chamber, the Rubicon Ignimbrite magma had a temperature of ≥ 780 °C and contained ≥ 4 wt.% H2O. Each formation, and indeed smaller volumes of rock, appears to have been produced by partial melting of slightly contrasting greywackes in a protolith with spatial variations in its chemistry and mineralogy, with the magma delivered in batches to a high-level chamber. The Rubicon Ignimbrite magmas underwent some internal differentiation, probably by crystal settling, prior to eruption, and variations in the Lake Mountain Ignimbrite are most probably due to small but variable degrees of peritectic phase entrainment. The limited gradation between the Rubicon Ignimbrite and Lake Mountain Ignimbrite is due to minor, pre-eruption mixing across the magma interface. Such limited mixing between individual magma batches appears typical of anatectic granitic magmas.

  15. A multi-isotope approach to understanding the evolution of Cenozoic magmatism in the northeastern Basin and Range: Results from igneous rocks in the Albion-Raft River-Grouse Creek metamorphic core complex

    NASA Astrophysics Data System (ADS)

    Konstantinou, A.; Strickland, A.; Miller, E. L.

    2012-12-01

    Deep crustal rocks exposed by extensional processes in metamorphic core complexes provide a unique opportunity to address the magmatic and isotopic evolution of the crust and assess the relative crust versus mantle contributions in Cenozoic igneous rocks exposed in the complexes. The Albion-Raft River-Grouse Creek metamorphic core complex exposes mid-crustal rocks that resided at depths of ~15-20 km before the onset of Cenozoic extension. Three major Cenozoic magmatic events are represented in the complex and have been studied using multiple isotopic systems (whole rock Sr and Nd coupled with the Oxygen isotopes in zircon). These three major events are: (1) 42-31 Ma intrusion of a composite plutonic complex of calc-alkaline composition that intrudes both upper crustal rocks (~5-10 km depth) and deeper rocks. (2) A 32-25 Ma plutonic complex, with evolved calc-alkaline composition that intruded in the middle crust (~12-15 km depth), and (3) A 10-8 Ma bimodal (basalt-rhyolite) suite of volcanic rocks that contain high-T anhydrous mineral assemblages erupted across the complex. The pre-extensional crust consisted of an upper crust composed primarily of Neoproterozoic through Triassic metasedimentary rocks (schist and quartzite at its base and limestone at its top). The middle crust consists of late Archean orthogneiss with evolved composition (metamorphosed peraluminous granite) with average 87Sr/86Sr40~0.800, ɛNd40~ -43.4 and δ18Ozirc ~5.7‰. The lower crust is inferred to have been composed of Precambrian intermediate composition igneous rocks with average 87Sr/86Sr40~0.750, ɛNd40~ -37.5 and δ18Ozirc ~5.9‰, and Precambrian mafic rocks with average 87Sr/86Sr40~0.717, ɛNd40~ -25 and δ18Ozirc ~7.0‰. Existing and new data indicate that the 42-31 Ma upper crustal plutonic complex ranges in isotopic composition from 87Sr/86Sri=0.709-0.712, ɛNdi=-15 to -25 and δ18Ozirc 4.7-6.5‰. The composition of the 32-25 Ma middle crustal plutonic complex ranges from 87Sr

  16. U-Pb geochronology documents out-of-sequence emplacement of ultramafic layers in the Bushveld Igneous Complex of South Africa

    NASA Astrophysics Data System (ADS)

    Mungall, James E.; Kamo, Sandra L.; McQuade, Stewart

    2016-11-01

    Layered intrusions represent part of the plumbing systems that deliver vast quantities of magma through the Earth's crust during the formation of large igneous provinces, which disrupt global ecosystems and host most of the Earth's endowment of Pt, Ni and Cr deposits. The Rustenburg Layered Suite of the enormous Bushveld Igneous Complex of South Africa has been presumed to have formed by deposition of crystals at the floor of a subterranean sea of magma several km deep and hundreds of km wide called a magma chamber. Here we show, using U-Pb isotopic dating of zircon and baddeleyite, that individual chromitite layers of the Rustenburg Layered Suite formed within a stack of discrete sheet-like intrusions emplaced and solidified as separate bodies beneath older layers. Our U-Pb ages and modelling necessitate reassessment of the genesis of layered intrusions and their ore deposits, and challenge even the venerable concept of the magma chamber itself.

  17. U–Pb geochronology documents out-of-sequence emplacement of ultramafic layers in the Bushveld Igneous Complex of South Africa

    PubMed Central

    Mungall, James E.; Kamo, Sandra L.; McQuade, Stewart

    2016-01-01

    Layered intrusions represent part of the plumbing systems that deliver vast quantities of magma through the Earth's crust during the formation of large igneous provinces, which disrupt global ecosystems and host most of the Earth's endowment of Pt, Ni and Cr deposits. The Rustenburg Layered Suite of the enormous Bushveld Igneous Complex of South Africa has been presumed to have formed by deposition of crystals at the floor of a subterranean sea of magma several km deep and hundreds of km wide called a magma chamber. Here we show, using U–Pb isotopic dating of zircon and baddeleyite, that individual chromitite layers of the Rustenburg Layered Suite formed within a stack of discrete sheet-like intrusions emplaced and solidified as separate bodies beneath older layers. Our U–Pb ages and modelling necessitate reassessment of the genesis of layered intrusions and their ore deposits, and challenge even the venerable concept of the magma chamber itself. PMID:27841347

  18. U-Pb geochronology documents out-of-sequence emplacement of ultramafic layers in the Bushveld Igneous Complex of South Africa.

    PubMed

    Mungall, James E; Kamo, Sandra L; McQuade, Stewart

    2016-11-14

    Layered intrusions represent part of the plumbing systems that deliver vast quantities of magma through the Earth's crust during the formation of large igneous provinces, which disrupt global ecosystems and host most of the Earth's endowment of Pt, Ni and Cr deposits. The Rustenburg Layered Suite of the enormous Bushveld Igneous Complex of South Africa has been presumed to have formed by deposition of crystals at the floor of a subterranean sea of magma several km deep and hundreds of km wide called a magma chamber. Here we show, using U-Pb isotopic dating of zircon and baddeleyite, that individual chromitite layers of the Rustenburg Layered Suite formed within a stack of discrete sheet-like intrusions emplaced and solidified as separate bodies beneath older layers. Our U-Pb ages and modelling necessitate reassessment of the genesis of layered intrusions and their ore deposits, and challenge even the venerable concept of the magma chamber itself.

  19. Architecture of the Igneous Lower Crust at Oceanic Core Complexes: constraints from IODP Hole U1309D

    NASA Astrophysics Data System (ADS)

    Christofferson, C. A.; Cheadle, M. J.; John, B. E.; Schoolmeesters, N.; Swapp, S. M.; Grimes, C. B.

    2011-12-01

    Slow spreading mid-ocean ridges are a ubiquitous part of the global ridge system, yet remain poorly understood. The crust produced at these ridges is fundamentally different than that produced at fast spreading ridges where the crustal architecture largely conforms to the standard Penrose type crust. At slow spread ridges, a reduced magma supply to the crust allows extensional faulting to play a much more important role in accommodating plate separation than at fast spread ridges. Oceanic core complexes (OCCs), a product of such faulting, denude lower crust to the surface via detachment faulting, and thus provide a means to study the architecture of slow spread lower crust. We report a detailed lithologic analysis of IODP Hole U1309D drilled into the Atlantis Massif OCC (30°N MAR). The abundance of sharp contacts between thin inter-layered gabbroic and ultramafic rocks throughout the core supports crustal construction via small (10-40m thick) injections of magma. Paleomagnetic remanance data allows re-orientation of the observed contacts and igneous fabrics to their original orientation at intrusion, and suggest that most contacts and fabrics were sub-vertical. These data therefore imply that construction of slow spread gabbroic lower crust at OCCs is dominated by dike-like intrusions rather than by sills. Combined U-Pb and (U-Th)/He zircon thermochronometry are used to predict a 3-4km thick zone of accretion that lies 6-7 km below seafloor, at the root of the detachment fault. Existing seismic data estimate the depth of the Moho to be 5km at Atlantis Massif constraining the width of the accretion zone in the footwall of the detachment fault to be 4km. Igneous fabrics from unfaulted gabbroic rocks provide an additional major constraint on the processes occurring within this zone of magmatic accretion. Electron backscatter diffraction (EBSD) was used to characterize the fabrics of slow-spread gabbros from the Atlantis Massif OCC, and other OCCs on the MAR (the 15

  20. 40Ar/39Ar hornblende and biotite geochronology of the Bulfat Igneous Complex, Zagros Suture Zone, NE Iraq: New insights on complexities of Paleogene arc magmatism during closure of the Neotethys Ocean

    NASA Astrophysics Data System (ADS)

    Aswad, Khalid J.; Ali, Sarmad A.; Al. Sheraefy, Ruaa M.; Nutman, Allen P.; Buckman, Solomon; Jones, Brian G.; Jourdan, F.

    2016-12-01

    In NE Iraq, the eastern edge of the Arabian plate is overlain by arc rock allochthons whose genesis and tectonic emplacement were related to the consumption and closure of the Neotethys Ocean. This paper demonstrates the occurrence of unrelated Paleogene arc rocks in two adjacent allochthons. The Bulfat Igneous Complex at Wadi Rashid (NE Iraq) is an intrusion within the Upper Allochthon Albian-Cenomanian Gimo-Qandil sequence suprasubduction zone assemblage. A thrust separates this allochthon from the underlying Lower Allochthon of the Eocene-Oligocene Walash-Naopurdan volcanic-sedimentary arc rocks. The Bulfat Igneous Complex at Wadi Rashid consists of gabbro and granitic composite intrusions in which components mingle down to a small scale. Textural relationships in the Bulfat Igneous Complex rocks indicate emplacement at high crustal levels with rapid cooling, which is consistent with amphibole geobarometry indicating crystallisation pressures between 250 and 300 Mpa. Ti-rich igneous pargasite and Ti-rich igneous Fe-biotite from gabbroic and granitic components yielded 40Ar/39Ar ages of 39.23 ± 0.21 and 38.87 ± 0.24 Ma respectively. These ages agree within analytical error and suggest coeval emplacement and rapid cooling of mafic and felsic magmas in the Eocene, in an event that was distinct and much younger than the host Albian-Cenomanian rocks. This igneous event was unrelated to formation of Cenozoic rocks in the underlying, tectonically separate, lower allochthon. The trace element signatures of the Wadi Rashi volcanic rocks show volcanic-arc characteristics for the granites and the gabbroic rocks resemble E type MORB. The presence of Eocene arc-related rocks in two allochthons suggests complexity in Paleogene subduction systems, with possibly two subduction zones operating at that time.

  1. Middle Miocene nepheline-bearing mafic and evolved alkaline igneous rocks at House Mountain, Arizona Transition Zone, north-central Arizona

    SciTech Connect

    Wittke, J.; Holm, R.F.; Ranney, W.D.R. . Dept. of Geology)

    1993-04-01

    The Middle Miocene House Mountain shield volcano is located on the northern margin of the Arizona Transition Zone, about 7 km SW of Sedona, AZ. Deep erosion has exposed internal structural and stratigraphic relationships of the volcano. Mapping documents two igneous suites: (1) alkali basalt to trachyte and alkali-feldspar syenite, and (2) olivine melanephelinite, nepheline monzodiorite, nepheline monzosyenite and nepheline syenite. The rocks of the first suite occur as dikes and flows, which, with a thick pyroclastic section, are the principal units of the volcano. The melanephelinite is nonvesicular and intruded as a large irregular dike and several smaller dikes. The nepheline-bearing syenitic rocks, which are phaneritic with nepheline and clinopyroxene crystals up to 1 cm in diameter, occur as pods and sheets within the melanephelinite. Also within the melanephelinite are wispy leucocratic segregations, syenitic fracture-fillings, and ocelli. The largest phaneritic sheet is [approx]18 m thick; it displays crude subhorizontal compositional banding and vuggy surfaces. The latter indicate that the magmas were fluid-rich. Compositions intermediate between the melanephelinite and syenitic rocks have not been found. Although the syenitic rocks are coarse-grained, mapping indicates the they are near the summit of the volcano and were probably emplaced at a depth of less than 1 km, possibly of only a few hundred meters. The field relationships of the phaneritic rocks can be explained by ascent and coalescence of immiscible syenitic liquids within the melanephelinite dike. Calculated density contrasts between melanephelinite and syenitic liquids exceed 0.2 g/cm[sup 3].

  2. 916 Ma Pole for southwestern Baltica: palaeomagnetism of the Bjerkreim-Sokndal layered intrusion, Rogaland Igneous Complex, southern Norway

    NASA Astrophysics Data System (ADS)

    Brown, Laurie L.; McEnroe, Suzanne A.

    2015-10-01

    The Rogaland Igneous Complex (RIC) in southern Norway intruded into post-Sveconorwegian granulite facies crust ˜930 Ma. It includes three massif anorthosites, several small leuconorite bodies and the ˜7 km thick norite-quartz mangerite layered Bjerkreim-Sokndal (BKS) intrusion. The intrusion consists of five rhythmic megaunits created by repeated magma influxes topped by a transition zone and more evolved mangerites and quartz mangerites. Over 70 palaeomagnetic sites have been collected in the BKS, sampling all the megacyclic subunits and overlying mangerites. Remanence within the BKS is held in hemo-ilmenite-only rocks (lower parts of the megacyclic units), mixed hemo-ilmenite and magnetite rocks (upper parts of the lower megacyclic units) and magnetite only rocks in the upper highest megacyclic unit and overlying mangerites. Due to the different oxides present magnetic susceptibility varies over four orders of magnitude with a bimodal distribution (mean susceptibility of 6.4 × 10-3 SI for hemo-ilmenite rocks, and 8.7 × 10-2 SI for magnetite rocks). NRM values do not show a strong bimodal distribution as many of the rocks lacking magnetite have hemo-ilmenite with strong lamellar magnetism; average NRM for the entire suite is 8.83 A m-1. All sites within the cyclic part of the intrusion have stable remanence and produce well-clustered site means. Samples from the upper mangerite rocks, dominated by MD magnetite, are commonly unstable and not all sites provide acceptable data. Mean directions for 66 sites spanning the entire intrusion are I = -73.5°, D = 303.4°, with α95 = 3.7° and k = 24. The resulting pole position is at 35.9°S and 217.9°E, with a palaeolatitude for this part of Baltica of -59.4°. Examination of the magnetic mineralogy combined with geochronology for RIC rocks and cooling rates for the region yields an age of magnetization of 916 Ma. Metamorphic country rocks yield similar directions at least 10 km from the contact, confirming the

  3. The Precambrian Singo Igneous Complex (SIC), Uganda Revealed As a Mineralized Nested Ring Complex Using High Resolution Airborne Radiometric and Magnetic Data.

    NASA Astrophysics Data System (ADS)

    Atekwana, E. A.; LePera, A.; Abdelsalam, M. G.; Katumwehe, A. B.; Achang, M.

    2014-12-01

    We used high-resolution radiometrics and aeromagnetic data to investigate the Precambrian Singo Igneous Complex (SIC) in Uganda. The SIC covers an area of about 700 km² and is host to hydrothermally formed economic minerals such as Gold and Tungsten. The distribution of the ore deposits is not well known and current mine workings are limited to the western margins of the complex. Our objectives were to (1) provide a detailed geological map of the SIC and surrounding, (2) investigate relationships between preserved intrusive bodies and Precambrian tectonic structures to provide insight into emplacement of the complex, (3) examine links between magma emplacement, discontinuities and hydrothermal alteration (4) generate two-dimensional (2-D) and three-dimensional (3-D) models of the complex to understand its subsurface geometry, (5) investigate the relationship between the structure of the SIC and mineral occurrences as an aid to future exploration programs. Edge enhancement filters such as the analytical signal, vertical and tilt derivatives were applied to the magnetic data. In addition, 2-D and 3-D models were produced using Geosoft's GM-SYS 2-D and Voxi modules. The filtered data provided unprecedented structural details of the complex and revealed the following: (1) the edge of the SIC is characterized by higher magnetic susceptibility and Thorium content than its interior, (2) the SIC is characterized by eight to nine nested ring complexes with diameters ranging from 2.5 to 14 km, (3) the 3-D inversion suggests near vertical walls for the ring complexes extending to a depth of about 7 km, (4) the SIC was emplaced within a Precambrian folded basement and was traversed by numerous NW-trending dykes and (5) present day mining activities are concentrated within the folded basement units although occurrences of Tungsten and Gold are found associated with the highly magnetized edge of the ring complexes. We interpret the highly magnetized edges of the nested ring

  4. Two Distinct Sets of Magma Sources in Cretaceous Rocks From Magnet Cove, Prairie Creek, and Other Igneous Centers of the Arkansas Alkaline Province, USA

    NASA Astrophysics Data System (ADS)

    Duke, G. I.; Carlson, R. W.; Eby, G. N.

    2008-12-01

    Two distinct sets of magma sources from the Arkansas alkaline province (~106-89 Ma) are revealed by Sr-Nd-Pb isotopic compositions of olivine lamproites vs. other alkalic rock types, including carbonatite, ijolite, lamprophyres, tephrite, malignite, jacupirangite, phonolite, trachyte, and latite. Isotopic compositions of diamond-bearing olivine lamproites from Prairie Creek and Dare Mine Knob point to Proterozoic lithosphere as an important source, and previous Re-Os isotopic data indicate derivation from subcontinental mantle lithosphere. Both sources were probably involved in lamproite generation. Magnet Cove carbonatites and other alkalic magmas were likely derived from an asthenospheric source. Lamproite samples are isotopically quite different from other rock types in Sr-Nd-Pb isotopic space. Although three lamproite samples from Prairie Creek have a large range of SiO2 contents (40-60 wt %), initial values of ɛNd (-10 to -13), 206Pb/204Pb (16.61-16.81), 207Pb/204Pb (15.34-15.36), and 208Pb/204Pb (36.57-36.76) are low and similar. Only 87Sr/86Sr(i) displays a wide range in the Prairie Creek lamproites (0.70627-0.70829). A fourth lamproite from Dare Mine Knob has the most negative ɛNd(i) of -19. Lamproite isotope values show a significant crustal component and isotopically overlap subalkalic rhyolites from the Black Hills (SD), which assimilated Proterozoic crust. Six samples of carbonatite, ijolite, and jacupirangite from Magnet Cove and Potash Sulphur Springs exhibit the most depleted Sr-Nd isotopic signatures of all samples. For these rock types, 87Sr/86Sr(i) is 0.70352 - 0.70396, and ɛNd(i) is +3.8 - +4.3. Eight other rock types have a narrow range of ɛNd(i) (+1.9 - +3.7), but a wide range of 87Sr/86Sr(i) (0.70424 - 0.70629). These 14 samples comprise a fairly tight cluster of Pb isotopic values: 206Pb/204Pb (18.22-19.23), 207Pb/204Pb (15.54-15.62), and 208Pb/204Pb (38.38-38.94), suggesting very little crustal assimilation. They are most similar to EM-2

  5. U-Pb Dating, whole rock and Sr-Nd-Pb-O isotope geochemistry of collisional magmatism in the CACC: Çiçekdaǧ igneous complex (ÇIC)

    NASA Astrophysics Data System (ADS)

    Deniz, Kiymet; Kagan Kadioglu, Yusuf; Stuart, Finlay; Ellam, Rob; Boyce, Adrian; Condon, Daniel

    2015-04-01

    The closure of Neotethys induced from calcalkaline through alkaline magmatism within the Central Anatolia Crystalline Complex (CACC) during the late Cretaceous-early Paleogene. Timing of these magmatism is very important for understanding the magmato-tectonic evolution and the relation with the collision. Despite the genesis of felsic products are well understood, there is lack of petrogenetic explanation about especially alkaline mafic products. The relation between Neotethyan ophiolites and late alkaline dykes which haven't reported before is the most important undeclared gap. Çiçekdağ igneous complex (ÇIC) is one of the best area for explaining all of these problems within the CACC. In accordance with these purposes, we have carried out detailed petrographic, whole rock geochemical, Sr-Nd-Pb-O isotopic and geochronological (U/Pb and Ar/Ar) study of the rocks in the ÇIC in order to unravel the magmatic history of the CACC and thus constrain the tectonic history. The intrusive rocks of the ÇIC are differentiated into four main group as an ophiolites, calcalkaline series, alkaline series and late alkaline dykes. The felsic and mafic units intruded to the ophiolitic rocks. The calcalkaline series mostly composed of monzonites and monzodiorite porphyry whereas the alkaline series consist of syenites and feldspathoid-bearing gabbros. Variations in the major oxide compositions of both rock series can be attributed with fractionation of clinopyroxene, plagioclase, amphibole, apatite and iron titan oxide minerals. The high 87Sr/86Sr and low 143Nd/144Nd of both series are indicative of mantle sources with large continental crustal components. Feldspar and quartz oxygen isotope data from calcalkaline and alkaline series have a range of δ18O values 5.1-11.4o 8.3-9.2o and 7.7-14.1o 10.2-13.7o respectively and are compatible with the values for I-A-type granitoids. Both rock series represent the mixed (mantle-crustal) origin. The combination of all data suggest that

  6. Petrogenesis of coeval silica-saturated and silica-undersaturated alkaline rocks: Mineralogical and geochemical evidence from the Saima alkaline complex, NE China

    NASA Astrophysics Data System (ADS)

    Zhu, Yu-Sheng; Yang, Jin-Hui; Sun, Jin-Feng; Zhang, Ji-Heng; Wu, Fu-Yuan

    2016-03-01

    A combined study of zircon U-Pb ages, mineral chemistry, whole-rock elements and Sr-Nd-Hf isotopes was carried out for the Saima alkaline complex in the northeastern China, in order to investigate the source and petrogenesis of coeval silica-saturated and silica-undersaturated alkaline rocks. The Saima alkaline complex consists of nepheline syenites, quartz-bearing syenites and alkaline volcanic rocks (i.e., phonolite and trachyte), with minor mafic dikes and carbonatitic veins. Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and secondary ion mass spectrometry (SIMS) zircon U-Pb dating gives consistent ages of 230-224 Ma for these rocks, suggesting that they are coeval. All alkaline rocks in the Saima complex are enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), and depleted in high field strength elements (HFSEs) with significant negative Nb, Ta and Ti anomalies. Geochemical data and Sr-Nd-Hf isotopic compositions indicate that the various alkaline rocks were all derived from partial melting of an ancient, re-enriched lithospheric mantle in the garnet stability field, but experienced variable siliceous- or carbonate-rich crustal contamination. Based on petrographic evidence, mineral compositions, and whole-rock geochemical data, two distinct magmatic evolutionary trends are proposed to explain the coeval emplacement of the various rock types within the Saima alkaline complex. The silica-undersaturated rocks (nepheline syenites and phonolites) result from alkali feldspar + apatite + titanite crystal fractionation of an alkaline mafic parental melt combined with assimilation of marine carbonate host rocks. In contrast, the generation of silica-saturated rocks (quartz-bearing syenites and trachytes) may be attributed to subsequent and continued clinopyroxene + apatite + biotite crystal fractionation coupled with assimilation of siliceous sediments.

  7. Variations in the Pb isotope composition in polyformational magmatic rocks of the Ketkap-Yuna igneous province of the Aldan Shield: Evidence for mantle-crust interaction

    NASA Astrophysics Data System (ADS)

    Polin, V. F.; Dril, S. I.; Khanchuk, A. I.; Velivetskaya, T. A.; Vladimirova, T. A.; Il'ina, N. N.

    2016-06-01

    The Pb isotope composition of polyformational Mesozoic igneous rocks of the Ketkap-Yuna igneous province (KYIP) and lower crustal metamorphic rocks of the Batomga granite-greenstone area (the complex of the KYIP basement) of the Aldan Shield was studied for the first time. Based on the data obtained, several types of material sources participating in petrogenetic processes were distinguished. The mantle source identified as PREMA is registered in most of the igneous formations and predominates in mafic alkaline rocks. According to the isotope characteristics, the upper crustal source corresponds to a source of the "Orogen" type by the model of "plumbotectonics" or to the average composition of the continental crust by the Stacey-Kramers model. The lower crust is the third material source; however, the type of lower crustal protolith involved in the igneous process is still not defined, which makes difficult to estimate its role in the petrogenetic processes.

  8. Arc-continent collision and the formation of continental crust: A new geochemical and isotopic record from the Ordovician Tyrone Igneous Complex, Ireland

    USGS Publications Warehouse

    Draut, Amy E.; Clift, Peter D.; Amato, Jeffrey M.; Blusztajn, Jerzy; Schouten, Hans

    2009-01-01

    Collisions between oceanic island-arc terranes and passive continental margins are thought to have been important in the formation of continental crust throughout much of Earth's history. Magmatic evolution during this stage of the plate-tectonic cycle is evident in several areas of the Ordovician Grampian-Taconic orogen, as we demonstrate in the first detailed geochemical study of the Tyrone Igneous Complex, Ireland. New U-Pb zircon dating yields ages of 493 2 Ma from a primitive mafic intrusion, indicating intra-oceanic subduction in Tremadoc time, and 475 10 Ma from a light rare earth element (LREE)-enriched tonalite intrusion that incorporated Laurentian continental material by early Arenig time (Early Ordovician, Stage 2) during arc-continent collision. Notably, LREE enrichment in volcanism and silicic intrusions of the Tyrone Igneous Complex exceeds that of average Dalradian (Laurentian) continental material that would have been thrust under the colliding forearc and potentially recycled into arc magmatism. This implies that crystal fractionation, in addition to magmatic mixing and assimilation, was important to the formation of new crust in the Grampian-Taconic orogeny. Because similar super-enrichment of orogenic melts occurred elsewhere in the Caledonides in the British Isles and Newfoundland, the addition of new, highly enriched melt to this accreted arc terrane was apparently widespread spatially and temporally. Such super-enrichment of magmatism, especially if accompanied by loss of corresponding lower crustal residues, supports the theory that arc-continent collision plays an important role in altering bulk crustal composition toward typical values for ancient continental crust. ?? 2009 Geological Society of London.

  9. Polyhydroxyflavones as extractants. Communication 7. Solvent extraction of europrium complexes with morin from alkaline media

    SciTech Connect

    Blank, A.B.

    1985-09-01

    This paper studies the analytical application of europium (III)-morin complex which is formed in alkaline medium and has an intense color. The extent of europium extraction was determined by adding to the extract a morin solution in isoamyl alcohol in a 50-100-fold excess with respect to europium. The dependence of the optical density of the extracts on the ph in the system europium (III)-morin-water-organic solvent for different excesses of the reagent is shown: this indicates formation of two extractable complexes, one being dominant in the pH range 4-7, the other at pH greater than or equal to 8.5. The extraction of the europium (III)-morin complex from alkaline solution is used for direct extraction-photometric determination of europium(III) in compounds of elements having amphoteric properties or forming amines (Zns, Mo0/sub 3/).

  10. Homoleptic alkaline earth metal bis(trifluoromethanesulfonyl)imide complex compounds obtained from an ionic liquid.

    PubMed

    Babai, Arash; Mudring, Anja-Verena

    2006-04-17

    The first homoleptic alkaline earth bis(trifluoromethanesulfonyl)imide (Tf2N) complexes [mppyr]2[Ca(Tf2N)4], [mppyr]2[Sr(Tf2N)4], and [mppyr][Ba(Tf2N)3] were crystallized from a solution of the respective alkaline earth bis(trifluoromethanesulfonyl)imide and the ionic liquid [mppyr][Tf2N] (mppyr = 1,1-N-methyl-N-propylpyrrolidinium). In the calcium and strontium compounds, the alkaline earth metal (AE) is coordinated by four bidentately chelating Tf2N ligands to form isolated (distorted) square antiprismatic [AE(Tf2N)4]2- complexes which are separated by N-methyl-N-propylpyrrolidinium cations. In contrast, the barium compound, [mppyr][Ba(Tf2N)3], forms an extended structure. Here the alkaline earth cation is surrounded by six oxygen atoms belonging to three Tf2N- anions which coordinate in a bidentate chelating fashion. Three further oxygen atoms of the same ligands are linking the Ba2+ cations to infinite (infinity)(1)[Ba(Tf2N)3] chains.

  11. Application of remote sensing to the geological study of the alkaline complex region of Itatiaia. [Brazil

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N. (Principal Investigator); Rodrigues, J. E.

    1980-01-01

    The methodology of remote sensing applied to geological study in a complex area was evaluated. Itatiaia was selected as a test area, which covers the alkaline massives and its precambrian basement. LANDSAT-MSS and radar mosaic of the RADAMBRASIL Project were used for photointerpretation. Previous geological works were consulted and many discrepancies in the distribution of stratigraphic units were found. Moreover, structural lineaments and talus deposits were clearly delineated.

  12. Lunar igneous intrusions.

    PubMed

    El-Baz, F

    1970-01-02

    Photographs taken from Apollo 10 and 11 reveal a number of probable igneous intrusions, including three probable dikes that crosscut the wall and floor of an unnamed 75-kilometer crater on the lunar farside. These intrusions are distinguished by their setting, textures, structures, and brightness relative to the surrounding materials. Recognition of these probable igneous intrusions in the lunar highlands slupports the indications of the heterogeneity of lunar materials and the plausibility of intrusive igneous activity, in addition to extrusive volcanism, on the moon.

  13. The Ezhimala Igneous Complex, southern India: Possible imprint of Late Cretaceous magmatism within rift setting associated with India-Madagascar separation

    NASA Astrophysics Data System (ADS)

    Mohan, M. Ram; Shaji, E.; Satyanarayanan, M.; Santosh, M.; Tsunogae, T.; Yang, Qiong-Yan; Dhanil Dev, S. G.

    2016-05-01

    The gabbro-granophyre-granite complex of Ezhimala emplaced along the western rifted continental margin of India preserves evidence for bimodal magmatism, with related magma mixing and mingling processes. Here we report petrological, geochemical, zircon U-Pb geochronological and Lu-Hf isotopic data from the Ezhimala Igneous Complex (EIC) that provide insights into the Late Cretaceous magmatic activity. Field investigations and petrographic observations in Zircon U-Pb data from the granophyres show emplacement ages of 93.21 ± 0.6 Ma and 94.26 ± 0.92 Ma. The evolved Lu-Hf isotopic systematics for these rocks are indicative of the involvement of older crustal material during magma genesis. The geochemical systematics together with isotopic data suggest magma generation in a rift-related setting, and interaction with or melting of Neoproterozoic basement rocks. The timing of magmatism broadly correlates with the Late Cretaceous Marion hotspot activity which is considered to be responsible for the break-up of India and Madagascar. We thus interpret the EIC to be one of the rare signatures in southern India for the final phase of rifting of Gondwana.

  14. U-Pb ages, geochemistry, C-O-Nd-Sr-Hf isotopes and petrogenesis of the Catalão II carbonatitic complex (Alto Paranaíba Igneous Province, Brazil): implications for regional-scale heterogeneities in the Brazilian carbonatite associations

    NASA Astrophysics Data System (ADS)

    Guarino, Vincenza; Wu, Fu-Yuan; Melluso, Leone; de Barros Gomes, Celso; Tassinari, Colombo Celso Gaeta; Ruberti, Excelso; Brilli, Mauro

    2016-09-01

    The Catalão II carbonatitic complex is part of the Alto Paranaíba Igneous Province (APIP), central Brazil, close to the Catalão I complex. Drill-hole sampling and detailed mineralogical and geochemical study point out the existence of ultramafic lamprophyres (phlogopite-picrites), calciocarbonatites, ferrocarbonatites, magnetitites, apatitites, phlogopitites and fenites, most of them of cumulitic origin. U-Pb data have constrained the age of Catalão I carbonatitic complex between 78 ± 1 and 81 ± 4 Ma. The initial strontium, neodymium and hafnium isotopic data of Catalão II (87Sr/86Sri = 0.70503-0.70599; ɛNdi = -6.8 to -4.7; 176Hf/177Hf = 0.28248-0.28249; ɛHfi = -10.33 to -10.8) are similar to the isotopic composition of the Catalão I complex and fall within the field of APIP kimberlites, kamafugites and phlogopite-picrites, indicating the provenance from an old lithospheric mantle source. Carbon isotopic data for Catalão II carbonatites (δ13C = -6.35 to -5.68 ‰) confirm the mantle origin of the carbon for these rocks. The origin of Catalão II cumulitic rocks is thought to be caused by differential settling of the heavy phases (magnetite, apatite, pyrochlore and sulphides) in a magma chamber repeatedly filled by carbonatitic/ferrocarbonatitic liquids (s.l.). The Sr-Nd isotopic composition of the Catalão II rocks matches those of APIP rocks and is markedly different from the isotopic features of alkaline-carbonatitic complexes in the southernmost Brazil. The differences are also observed in the lithologies and the magmatic affinity of the igneous rocks found in the two areas, thus demonstrating the existence of regional-scale heterogeneity in the mantle sources underneath the Brazilian platform.

  15. Inhibition of acid, alkaline, and tyrosine (PTP1B) phosphatases by novel vanadium complexes.

    PubMed

    McLauchlan, Craig C; Hooker, Jaqueline D; Jones, Marjorie A; Dymon, Zaneta; Backhus, Emily A; Greiner, Bradley A; Dorner, Nicole A; Youkhana, Mary A; Manus, Lisa M

    2010-03-01

    In the course of our investigations of vanadium-containing complexes for use as insulin-enhancing agents, we have generated a series of novel vanadium coordination complexes with bidentate ligands. Specifically we have focused on two ligands: anthranilate (anc(-)), a natural metabolite of tryptophan, and imidizole-4-carboxylate (imc(-)), meant to mimic naturally occurring N-donor ligands. For each ligand, we have generated a series of complexes containing the V(III), V(IV), and V(V) oxidation states. Each complex was investigated using phosphatase inhibition studies of three different phosphatases (acid, alkaline, and tyrosine (PTP1B) phosphatase) as prima facia evidence for potential use as an insulin-enhancing agent. Using p-nitrophenyl phosphate as an artificial phosphatase substrate, the levels of inhibition were determined by measuring the absorbance of the product at 405nm using UV/vis spectroscopy. Under our experimental conditions, for instance, V(imc)(3) appears to be as potent an inhibitor of alkaline phosphatase as sodium orthovanadate when comparing the K(cat)/K(m) term. VO(anc)(2) is as potent an inhibitor of acid phosphatase and tyrosine phosphatase as the Na(3)VO(4). Thus, use of these complexes can increase our mechanistic understanding of the effects of vanadium in vivo.

  16. Direct electrochemiluminescence of gold nanoparticles bifunctionalized by luminol analogue-metal complexes in neutral and alkaline media.

    PubMed

    Shu, Jiangnan; Wang, Wei; Cui, Hua

    2015-07-21

    Electrochemiluminescence of gold nanoparticles bifunctionalized by luminol analogue-metal complexes was studied for the first time. Strong direct electrochemiluminescence was observed in neutral and alkaline media without an additional coreactant.

  17. ReOs isotope systematics of NiCu sulfide ores, Sudbury Igneous Complex, Ontario: evidence for a major crustal component

    USGS Publications Warehouse

    Walker, R.J.; Morgan, J.W.; Naldrett, A.J.; Li, C.; Fassett, J.D.

    1991-01-01

    Sudbury Igneous Complex sublayer ores from the Levack West, Falconbridge and Strathcona mines were analyzed for their Re and Os concentrations and Os isotopic compositions. The ReOs isotope systematics of three ores from the different mines give isochron ages of 1840 ?? 60 Ma, 1770 ?? 60 Ma and 1780 ?? 110 Ma, suggesting that the ReOs system became closed at the time of, or soon after the 1850 ?? 1 Ma crystallization age of the complex. The Os isotopic compositions of different portions of the complex at the time of crystallization varied considerably, with initial 187Os 186Os1850 ranging from 4.64 at Levack West to 7.55 at Strathcona. These heterogeneities require that the Os, and probably also the other platinum-group elements contained in the ores, were derived from at least two sources. In addition, the high initial 187Os 186Os ratios indicate that the Os was derived predominantly from ancient crust. Previous studies have suggested that the complex either crystallized from a mixture of mantle-derived basaltic melt and ancient continental crust, or was derived exclusively from the fusion of ancient continental crust resulting from a meteorite impact. Results of modelling suggest that if a contemporaneous mantle-derived basaltic melt was involved in the origin of the SIC, it likely contributed < 50% of the Os to all three ores. The large percentage of ancient crust involved in the production of the ores is most consistent with an interpretation of substantial crustal fusion resulting from meteorite impact. ?? 1991.

  18. Petrogenesis of the igneous Mucajaí AMG complex, northern Amazonian craton — Geochemical, U-Pb geochronological, and Nd-Hf-O isotopic constraints

    NASA Astrophysics Data System (ADS)

    Heinonen, A. P.; Fraga, L. M.; Rämö, O. T.; Dall'Agnol, R.; Mänttäri, I.; Andersen, T.

    2012-10-01

    The ca. 1525 Ma igneous Mucajaí anorthosite-monzonite-granite (AMG) complex in northern Brazil is a rare manifestation of Mesoproterozoic intraplate magmatism in the northern Amazonian Craton. The complex comprises a two-phase rapakivi granite batholith with subordinate quartz-fayalite monzonites and syenites and the closely associated Repartimento anorthosite. Zircon U-Pb (ID-TIMS) geochronology reveals that the anorthosite (1526 ± 2 Ma), monzonite (1526 ± 2 Ma), and the main-phase biotite-hornblende granite (1527 ± 2 Ma) of the complex intruded the Paleoproterozoic (~ 1.94 Ga) country rocks simultaneously at ~ 1526 Ma and that the more evolved biotite granite is marginally younger at 1519 ± 2 Ma. Intraplate magmatism in the Mucajaí region was relatively short-lived and lasted 12 million years (1529-1517 Ma) at maximum. The Nd (whole-rock, ID-TIMS; ɛNd from - 1.9 to - 2.8), Hf (zircon, LAM-ICP-MS; ɛHf from - 2.0 to - 3.1), and O (zircon, SIMS; δ18O from 6.1 to 7.0‰) isotopic compositions of the studied rocks are fairly uniform but still reveal a small degree of isotopic heterogeneity in the Paleoproterozoic crust enclosing the complex. The small isotopic differences observed in the two types of rapakivi granites (biotite-hornblende granite and biotite granite) may result either from an isotopically heterogeneous lower crustal source or, more likely, from contamination of the granitic magma derived from a lower crustal source during prolonged residence at upper crustal levels.

  19. Modal Petrology and Geostatistics of the Blue Hills Igneous Complex, Boston, Massachusetts, by Rietveld X-ray Diffraction: Multi-scalar Investigation of Volcanic and Intrusive Relationships

    NASA Astrophysics Data System (ADS)

    Besancon, J. R.; Spence, T. M.

    2004-12-01

    The Blue Hills Igneous Complex of eastern Massachusetts consists of mildly peralkaline volcanic and intrusive units including the Quincy Granite, the Blue Hills Porphyry, and a set of mainly pyroclastic rhyolite flow units traditionally called the Aporhyolite. Similar whole-rock chemistry has led most workers to assume that they are related rocks, despite some unclear field relationships. Kaktins (1976) divided the volcanic rocks into six units, but buried contacts do not permit confidence in either their number or stratigraphic position. To test a new method of modal analysis of these rocks, thirty-five samples were crushed, ground to approximately 5 micrometers, spray-dried to produce randomly oriented powder, and analyzed by x-ray diffraction. A constant eleven-phase Rietveld starting model was applied to the x-ray spectra, and then refined to produce a modal database of phase proportions in each sample. Geostatistical analysis with GIS software delineates a number of trends, with statistical measures of uncertainty. Aegirine in volcanics decreases in abundance with distance south from the E-W contact of volcanic rocks and granite. Riebeckite is found in the granite (both as veins and as apparently magmatic crystals) and the porphyry, but is less abundant or absent among the volcanic rocks. Where both amphibole and pyroxene are present, they are negatively correlated. The goal is to develop an additional tool for correlation of volcanic rocks, one based on mineral proportions in both aphanitic and phaneritic rocks.

  20. Resolving the Richat enigma: Doming and hydrothermal karstification above an alkaline complex

    NASA Astrophysics Data System (ADS)

    Matton, Guillaume; Jébrak, Michel; Lee, James K. W.

    2005-08-01

    The Richat structure (Sahara, Mauritania) appears as a large dome at least 40 km in diameter within a Late Proterozoic to Ordovician sequence. Erosion has created circular cuestas represented by three nested rings dipping outward from the structure. The center of the structure consists of a limestone-dolomite shelf that encloses a kilometer-scale siliceous breccia and is intruded by basaltic ring dikes, kimberlitic intrusions, and alkaline volcanic rocks. Several hypotheses have been presented to explain the spectacular Richat structure and breccia, but their origin remains enigmatic. The breccia body is lenticular in shape and irregularly thins at its extremities to only a few meters. The breccia was created during karst dissolution and collapse. Internal sediments fill the centimeter- to meter-scale cavities. Alkaline enrichment and the presence of Cretaceous automorphous neoformed K-feldspar demonstrate the hydrothermal origin of these internal sediments and their contemporaneity with magmatism. A model is proposed in which doming and the production of hydrothermal fluids were instrumental in creating a favorable setting for dissolution. The circular Richat structure and its breccia core thus represent the superficial expression of a Cretaceous alkaline complex with an exceptionally well preserved hydrothermal karst infilling at its summit.

  1. Crystal structures of Bacillus alkaline phytase in complex with divalent metal ions and inositol hexasulfate.

    PubMed

    Zeng, Yi-Fang; Ko, Tzu-Ping; Lai, Hui-Lin; Cheng, Ya-Shan; Wu, Tzu-Hui; Ma, Yanhe; Chen, Chun-Chi; Yang, Chii-Shen; Cheng, Kuo-Joan; Huang, Chun-Hsiang; Guo, Rey-Ting; Liu, Je-Ruei

    2011-06-03

    Alkaline phytases from Bacillus species, which hydrolyze phytate to less phosphorylated myo-inositols and inorganic phosphate, have great potential as additives to animal feed. The thermostability and neutral optimum pH of Bacillus phytase are attributed largely to the presence of calcium ions. Nonetheless, no report has demonstrated directly how the metal ions coordinate phytase and its substrate to facilitate the catalytic reaction. In this study, the interactions between a phytate analog (myo-inositol hexasulfate) and divalent metal ions in Bacillus subtilis phytase were revealed by the crystal structure at 1.25 Å resolution. We found all, except the first, sulfates on the substrate analog have direct or indirect interactions with amino acid residues in the enzyme active site. The structures also unraveled two active site-associated metal ions that were not explored in earlier studies. Significantly, one metal ion could be crucial to substrate binding. In addition, binding of the fourth sulfate of the substrate analog to the active site appears to be stronger than that of the others. These results indicate that alkaline phytase starts by cleaving the fourth phosphate, instead of the third or the sixth that were proposed earlier. Our high-resolution, structural representation of Bacillus phytase in complex with a substrate analog and divalent metal ions provides new insight into the catalytic mechanism of alkaline phytases in general.

  2. Chemical data and variation diagrams of igneous rocks from the Timber Mountain-Oasis Valley Caldera Complex, southern Nevada

    USGS Publications Warehouse

    Quinlivan, W.D.; Byers, F.M.

    1977-01-01

    Silica variation diagrams presented here are based on 162 chemical analyses of tuffs, lavas, and intrusives, representative of volcanic centers of the Timber Mountain-Oasis Valley caldera complex and cogenetic rocks of the Silent Canyon ca1dera. Most of the volcanic units sampled are shown on the U.S. Geological Survey geologic map of the Timber Mountain caldera area (I-891) and are described in U.S. Geological Survey Professional Paper 919. Early effusives of the complex, although slightly altered, are probably chemically, and petrographically, more like the calc-alkalic Fraction Tuff (Miocene) of the northern Nellis Air Force Base Bombing and Gunnery Range to the north, whereas effusives of later Miocene age, such as the Paintbrush and Timber Mountain Tuffs, are alkali-calcic.

  3. Pyroxene zonation trends in mafic nepheline syenite and ijolite, Diamond Jo quarry, Magnet Cove igneous alkalic complex, Arkansas

    SciTech Connect

    Flohr, M.J.K.; Ross, M.

    1985-01-01

    Compositions of pyroxenes from mafic nepheline syenite and ijolite from Magnet Cove (NS and IJ) define zoning trends that reflect changing conditions in the crystallizing magmas and are used to contrast Magnet Cove with other alkalic complexes. The Na-Mg-Fe/sup 2 +/+Mn plot is used to compare NS and IJ pyroxenes with pyroxenes from nepheline syenites from S. Qoroq Centre, Greenland, and the Coldwell Complex intrusions, Ontario. Trends from the three areas are similar, but differences exists. Zoning in individual NS grains is greater than ranges for individual intrusions from S. Qoroq. Also, NS pyroxenes with compositions more magnesisan than Mg/sub 50/Nag are more Al-rich than S. Qoroq and Coldwell pyroxenes, indicating crystallization from a more undersaturated magma. These NS pyroxenes also contain 2-3 times more Ti and Fe/sup 3 +/. Despite different concentrations of Al, Ti, and Fe/sup 3 +/, the general crystallization trends shown by all elements considered are similar in NS and S. Qoroq pyroxenes. Sparse biotite and the absence of amphibole in NS indicate an H/sub 2/O-poor parent magma compared with those of the Coldwell and S. Qoroq nepheline syenites, which contain these phases. Mg-rich biotites and pyroxenes in IJ indicate that it formed from a less evolved liquid than NS.

  4. REE mineralization in the carbonatites of the sung valley ultramafic-alkaline-carbonatite complex, Meghalaya, India

    NASA Astrophysics Data System (ADS)

    Sadiq, Mohd.; Ranjith, A.; Umrao, Ravi

    2014-12-01

    The Early Cretaceous Sung Valley Ultramafic-Alkaline-Carbonatite (SUAC) complex intruded the Proterozoic Shillong Group of rocks and located in the East Khasi Hills and West Jaintia Hills districts of Meghalaya. The SUAC complex is a bowl-shaped depression covering an area of about 26 km2 and is comprised serpentinised peridotite forming the core of the complex with pyroxenite rim. Alkaline rocks are dominantly ijolite and nepheline syenite, occur as ring-shaped bodies as well as dykes. Carbonatites are, the youngest intrusive phase in the complex, where they form oval-shaped bodies, small dykes and veins. During the course of large scale mapping in parts of the Sung Valley complex, eleven carbonatite bodies were delineated. These isolated carbonatite bodies have a general NW-SE and E-W trend and vary from 20-125 m long and 10-40 m wide. Calcite carbonatite is the dominant variety and comprises minor dolomite and apatite and accessory olivine, magnetite, pyrochlore and phlogopite. The REE-bearing minerals identified in the Sung Valley carbonatites are bastnäsite-(Ce), ancylite-(Ce), belovite-(Ce), britholite-(Ce) and pyrochlore that are associated with calcite and apatite. The presence of REE carbonates and phosphates associated with REE-Nb bearing pyrochlore enhances the economic potential of the Sung Valley carbonatites. Trace-element geochemistry also reveals an enrichment of LREEs in the carbonatites and average ΣREE value of 0.102% in 26 bed rock samples. Channel samples shows average ΣREE values of 0.103 wt%. Moreover, few samples from carbonatite bodies has indicated relatively higher values for Sn, Hf, Ta and U. Since the present study focuses surface evaluation of REE, therefore, detailed subsurface exploration will be of immense help to determine the REE and other associated mineralization of the Sung Valley carbonatite prospect.

  5. Igneous evolution of a complex laccolith-caldera, the Solitario, Trans-Pecos Texas: Implications for calderas and subjacent plutons

    USGS Publications Warehouse

    Henry, C.D.; Kunk, M.J.; Muehlberger, W.R.; McIntosh, W.C.

    1997-01-01

    The Solitario is a large, combination laccolith and caldera (herein termed "laccocaldera"), with a 16-km-diameter dome over which developed a 6 x 2 km caldera. This laccocaldera underwent a complex sequence of predoming sill, laccolith, and dike intrusion and concurrent volcanism; doming with emplacement of a main laccolith; ash-flow eruption and caldera collapse; intracaldera sedimentation and volcanism; and late intrusion. Detailed geologic mapping and 40Ar/39Ar dating reveal that the Solitario evolved over an interval of approximately 1 m.y. in three distinct pulses at 36.0, 35.4, and 35.0 Ma. The size, duration, and episodicity of Solitario magmatism are more typical of large ash-flow calderas than of most previously described laccoliths. Small volumes of magma intruded as abundant rhyolitic to trachytic sills and small laccoliths and extruded as lavas and tuffs during the first pulse at 36.0 Ma. Emplacement of the main laccolith, doming, ash-flow eruption, and caldera collapse occurred at 35.4 Ma during the most voluminous pulse. A complex sequence of debris-flow and debris-avalanche deposits, megabreccia, trachyte lava, and minor ash-flow tuff subsequently filled the caldera. The final magmatic pulse at 35.0 Ma consisted of several small laccoliths or stocks and numerous dikes in caldera fill and along the ring fracture. Solitario rocks appear to be part of a broadly cogenetic, metaluminous suite. Peralkaline rhyolite lava domes were emplaced north and west of the Solitario at approximately 35.4 Ma, contemporaneous with laccolith emplacement and the main pulse in the Solitario. The spatial and temporal relation along with sparse geochemical data suggest that the peralkaline rhyolites are crustal melts related to the magmatic-thermal flux represented by the main pulse of Solitario magmatism. Current models of laccolith emplacement and evolution suggest a continuum from initial sill emplacement through growth of the main laccolith. Although the Solitario

  6. The Job Canyon caldera, Stillwater Range, west-central Nevada: A steeply tilted late Oligocene igneous complex

    SciTech Connect

    John, D.A.; Pickthorn, W.J. )

    1993-04-01

    The Job Canyon caldera (JCC) and underlying IXL pluton are the oldest ([approx]29 Ma) and most well preserved parts of the Stillwater caldera complex (SCC), southern Stillwater Range (SR). SCC consists of three partly overlapping calderas JCC, Poco Canyon caldera (PCC), and Elevenmile Canyon caldera (ECC) and the underlying IXL and Freeman Creek plutons. SCC was steeply tilted to the west or east by earliest Miocene extensional faulting exposing sections of late Oligocene rocks as thick as 10 km. JCC consists of 2 structural blocks separated by an E-striking fault zone that was later reactivated to form the north margins of PCC and ECC. The north block of JCC consists of 1.1 km of dacite and andesite lavas, overlain by 2 km of rhyolitic ash-flow tuff locally interbedded with megabreccia, overlain by 2.5 km of dacite and andesite lavas. The south block of JCC is broken into 5 small fault blocks that have thinner sequences of caldera fill consisting of rhyolite ash-flow tuff underlain locally by dacite and andesite lavas. Caldera collapse was accomplished both by large-scale displacement along steep bounding faults and by small displacement along high-angle faults in the interior of the caldera. Hydrothermal alteration of caldera fill is pervasive within JCC and in the upper part of the IXL pluton and appears to predate formation of PCC and tilting of SCC. Most alteration is propylitic and intensity of alteration increases downwards within caldera fill. Preliminary whole-rock [delta][sup 18]O values indicate that hydrothermal fluids were dominated by meteoric water. These values increase upwards to +5 to [minus]3 permil near the top suggesting that there was a steep temperature gradient with temperature increasing with depth. SCC was steeply tilted at about 24--23 Ma shortly following formation of PCC and ECC at about 25--24 Ma. Late Miocene--Holocene Basin and Range faulting has uplifted the SR exposing the older extensional faults and fossil hydrothermal system.

  7. Combination of alkaline phosphatase anti-alkaline phosphatase (APAAP)- and avidin-biotin-alkaline phosphatase complex (ABAP)-techniques for amplification of immunocytochemical staining of human testicular tissue.

    PubMed

    Davidoff, M S; Schulze, W; Holstein, A F

    1991-01-01

    An amplification procedure was developed for the visualization of antigens in human testis using monoclonal antibodies against desmin and vimentin. The technique combines the high sensitive and specific APAAP- and ABAP-methods. Depending on the quality of the antibodies used and the processing of the material prior to the immunocytochemical staining the amplification technique may be applied either as a single APAAP and ABAP- or as a double APAAP and ABAP-combination. Especially after the double amplification reaction a distinct increase of the staining intensity of the vimentin- (in Sertoli cells, myofibroblasts of the lamina propria, and fibroblasts of the interstitium) and desmin- (in myofibroblasts of the lamina propria and smooth muscle cells of the blood vessels) like immunoreactivity was observed. If different diazonium salts were used for the visualization of the alkaline phosphatase activity (e.g. Fast Red TR Salt, Fast Blue BB Salt) desmin- and vimentin-like immunoreactivity can be demonstrated in the same tissue section in a double sequential staining approach. For double staining, the alkaline phosphatase technique may be combined successfully with a technique or a combination that uses peroxidase as a marker.

  8. Multiple sulfur isotope and mineralogical constraints on the genesis of Ni-Cu-PGE magmatic sulfide mineralization of the Monchegorsk Igneous Complex, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Bekker, A.; Grokhovskaya, T. L.; Hiebert, R.; Sharkov, E. V.; Bui, T. H.; Stadnek, K. R.; Chashchin, V. V.; Wing, B. A.

    2016-12-01

    We present the results of a pilot investigation of multiple sulfur isotopes for the Ni-Cu-PGE sulfide mineralization of the ˜2.5 Ga Monchegorsk Igneous Complex (MIC). Base Metal Sulfide (BMS) compositions, Platinum Group Element (PGE) distributions, and Platinum Group Mineral (PGM) assemblages were also studied for different types of Ni-Cu-PGE mineralization. The uniformly low S content of the country rocks for the MIC as well as variable Sm-Nd isotope systematics and low-sulfide, PGE-rich mineralization of the MIC suggest that S saturation was reached via assimilation of silicates rather than assimilation of sulfur-rich lithologies. R-factor modeling suggests that the mixing ratio for silicate-to-sulfide melt was very high, well above 15,000 for the majority of our mineralized samples, as might be expected for the low-sulfide, PGE-rich mineralization of the MIC. Small, negative Δ33S values (from -0.23 to -0.04 ‰) for sulfides in strongly metamorphosed MIC-host rocks indicate that their sulfur underwent mass-independent sulfur isotope fractionation (MIF) in the oxygen-poor Archean atmosphere before it was incorporated into the protoliths of the host paragneisses and homogenized during metamorphism. Ore minerals from the MIC have similar Δ33S values (from -0.21 to -0.06 ‰) consistent with country rock assimilation contributing to sulfide saturation, but, also importantly, our dataset suggests that Δ33S values decrease from the center to the margin of the MIC as well as from early to late magmatic phases, potentially indicating that both local assimilation of host rocks and S homogenization in the central part of the large intrusion took place.

  9. Review of the complexation of tetravalent actinides by ISA and gluconate under alkaline to hyperalkaline conditions.

    PubMed

    Gaona, X; Montoya, V; Colàs, E; Grivé, M; Duro, L

    2008-12-12

    Isosaccharinic (ISA) and gluconic acids (GLU) are polyhydroxy carboxylic compounds showing a high affinity to metal complexation. Both organic ligands are expected in the cementitious environments usually considered for the disposal of low- and intermediate-level radioactive wastes. The hyperalkaline conditions imposed by cementitious materials contribute to the formation of ISA through cellulose degradation, whereas GLU is commonly used as a concrete additive. Despite the high stability attributed to ISA/GLU complexes of tetravalent actinides, the number and reliability of available experimental studies is still limited. This work aims at providing a general and comprehensive overview of the state of the art regarding Th, U(IV), Np(IV), and Pu(IV) complexes with ISA and GLU. In the presence of ISA/GLU concentrations in the range 10(-5)-10(-2) M and absence of calcium, An(IV)(OH)x(L)y complexes (An(IV)=Th, U(IV), Np(IV), Pu(IV); L=ISA, GLU) are expected to dominate the aqueous speciation of tetravalent actinides in the alkaline pH range. There is a moderate agreement among their stability, although the stoichiometry of certain An(IV)-GLU complexes is still ill-defined. Under hyperalkaline conditions and presence of calcium, the species CaTh(OH)4(L)2(aq) has been described for both ISA and GLU, and similar complexes may be expected to form with other tetravalent actinides. In the present work, the available thermodynamic data for An(IV)-ISA/GLU complexes have been reviewed and re-calculated to ensure the internal consistency of the stability constants assessed. Further modelling exercises, estimations based on Linear Free-Energy Relationships (LFER) among tetravalent actinides, as well as direct analogies between ISA and GLU complexes have also been performed. This approach has led to the definition of a speciation scheme for the complexes of Th, U(IV), Np(IV) and Pu(IV) with ISA and GLU forming in alkaline to hyperalkaline pH conditions, both in the absence and

  10. Review of the complexation of tetravalent actinides by ISA and gluconate under alkaline to hyperalkaline conditions

    NASA Astrophysics Data System (ADS)

    Gaona, X.; Montoya, V.; Colàs, E.; Grivé, M.; Duro, L.

    2008-12-01

    Isosaccharinic (ISA) and gluconic acids (GLU) are polyhydroxy carboxylic compounds showing a high affinity to metal complexation. Both organic ligands are expected in the cementitious environments usually considered for the disposal of low- and intermediate-level radioactive wastes. The hyperalkaline conditions imposed by cementitious materials contribute to the formation of ISA through cellulose degradation, whereas GLU is commonly used as a concrete additive. Despite the high stability attributed to ISA/GLU complexes of tetravalent actinides, the number and reliability of available experimental studies is still limited. This work aims at providing a general and comprehensive overview of the state of the art regarding Th, U(IV), Np(IV), and Pu(IV) complexes with ISA and GLU. In the presence of ISA/GLU concentrations in the range 10 - 5 -10 - 2 M and absence of calcium, An(IV)(OH) x(L) y complexes (An(IV) = Th, U(IV), Np(IV), Pu(IV); L = ISA, GLU) are expected to dominate the aqueous speciation of tetravalent actinides in the alkaline pH range. There is a moderate agreement among their stability, although the stoichiometry of certain An(IV)-GLU complexes is still ill-defined. Under hyperalkaline conditions and presence of calcium, the species CaTh(OH) 4(L) 2(aq) has been described for both ISA and GLU, and similar complexes may be expected to form with other tetravalent actinides. In the present work, the available thermodynamic data for An(IV)-ISA/GLU complexes have been reviewed and re-calculated to ensure the internal consistency of the stability constants assessed. Further modelling exercises, estimations based on Linear Free-Energy Relationships (LFER) among tetravalent actinides, as well as direct analogies between ISA and GLU complexes have also been performed. This approach has led to the definition of a speciation scheme for the complexes of Th, U(IV), Np(IV) and Pu(IV) with ISA and GLU forming in alkaline to hyperalkaline pH conditions, both in the

  11. Deciphering igneous and metamorphic events in high-grade rocks of the Wilmington complex, Delaware: Morphology, cathodoluminescence and backscattered electron zoning, and SHRIMP U-Pb geochronology of zircon and monazite

    USGS Publications Warehouse

    Aleinikoff, J.N.; Schenck, W.S.; Plank, M.O.; Srogi, L.A.; Fanning, C.M.; Kamo, S.L.; Bosbyshell, H.

    2006-01-01

    High-grade rocks of the Wilmington Complex, northern Delaware and adjacent Maryland and Pennsylvania, contain morphologically complex zircons that formed through both igneous and metamorphic processes during the development of an island-arc complex and suturing of the arc to Laurentia. The arc complex has been divided into several members, the protoliths of which include both intrusive and extrusive rocks. Metasedimentary rocks are interlayered with the complex and are believed to be the infrastructure upon which the arc was built. In the Wilmingto n Complex rocks, both igneous and metamorphic zircons occur as elongate and equant forms. Chemical zoning, shown by cathodoluminescence (CL), includes both concentric, oscillatory patterns, indicative of igneous origin, and patchwork and sector patterns, suggestive of metamorphic growth. Metamorphic monazites are chemically homogeneous, or show oscillatory or spotted chemical zoning in backscattered electron images. U-Pb geochronology by sensitive high resolution ion microprobe (SHRIMP) was used to date complexly zoned zircon and monazite. All but one member of the Wilmington Complex crystallized in the Ordovician between ca. 475 and 485 Ma; these rocks were intruded by a suite of gabbro-to-granite plutonic rocks at 434 ?? Ma. Detrital zircons in metavolcanic and metasedimentary units were derived predominantly from 0.9 to 1.4 Ga (Grenvillian) basement, presumably of Laurentian origin. Amphibolite to granulite facies metamorphism of the Wilmington Complex, recorded by ages of metamorphic zircon (428 ?? 4 and 432 ?? 6 Ma) and monazite (429 ?? 2 and 426 ?? 3 Ma), occurred contemporaneously with emplacement of the younger plutonic rocks. On the basis of varying CL zoning patterns and external morphologies, metamorphic zircons formed by different processes (presumably controlled by rock chemistry) at slightly different times and temperatures during prograde metamorphism. In addition, at least three other thermal episodes are

  12. Spirit Discovers New Class of Igneous Rocks

    NASA Technical Reports Server (NTRS)

    2006-01-01

    During the past two-and-a-half years of traversing the central part of Gusev Crater, NASA's Mars Exploration Rover Spirit has analyzed the brushed and ground-into surfaces of multiple rocks using the alpha particle X-ray spectrometer, which measures the abundance of major chemical elements. In the process, Spirit has documented the first example of a particular kind of volcanic region on Mars known as an alkaline igneous province. The word alkaline refers to the abundance of sodium and potassium, two major rock-forming elements from the alkali metals on the left-hand side of the periodic table.

    All of the relatively unaltered rocks -- those least changed by wind, water, freezing, or other weathering agents -- examined by Spirit have been igneous, meaning that they crystallized from molten magmas. One way geologists classify igneous rocks is by looking at the amount of potassium and sodium relative to the amount of silica, the most abundant rock-forming mineral on Earth. In the case of volcanic rocks, the amount of silica present gives scientists clues to the kind of volcanism that occurred, while the amounts of potassium and sodium provide clues about the history of the rock. Rocks with more silica tend to erupt explosively. Higher contents of potassium and sodium, as seen in alkaline rocks like those at Gusev, may indicate partial melting of magma at higher pressure, that is, deeper in the Martian mantle. The abundance of potassium and sodium determines the kinds of minerals that make up igneous rocks. If igneous rocks have enough silica, potassium and sodium always bond with the silica to form certain minerals.

    The Gusev rocks define a new chemical category not previously seen on Mars, as shown in this diagram plotting alkalis versus silica, compiled by University of Tennessee geologist Harry McSween. The abbreviations 'Na2O' and 'K2O' refer to oxides of sodium and potassium. The abbreviation 'SiO2' refers to silica. The abbreviation 'wt

  13. Petrology, geochemistry and zircon U-Pb geochronology of a layered igneous complex from Akarui Point in the Lützow-Holm Complex, East Antarctica: Implications for Antarctica-Sri Lanka correlation

    NASA Astrophysics Data System (ADS)

    Kazami, Sou; Tsunogae, Toshiaki; Santosh, M.; Tsutsumi, Yukiyasu; Takamura, Yusuke

    2016-11-01

    The Lützow-Holm Complex (LHC) of East Antarctica forms part of a complex subduction-collision orogen related to the amalgamation of the Neoproterozoic supercontinent Gondwana. Here we report new petrological, geochemical, and geochronological data from a metamorphosed and disrupted layered igneous complex from Akarui Point in the LHC which provide new insights into the evolution of the complex. The complex is composed of mafic orthogneiss (edenite/pargasite + plagioclase ± clinopyroxene ± orthopyroxene ± spinel ± sapphirine ± K-feldspar), meta-ultramafic rock (pargasite + olivine + spinel + orthopyroxene), and felsic orthogneiss (plagioclase + quartz + pargasite + biotite ± garnet). The rocks show obvious compositional layering reflecting the chemical variation possibly through magmatic differentiation. The metamorphic conditions of the rocks were estimated using hornblende-plagioclase geothermometry which yielded temperatures of 720-840 °C. The geochemical data of the orthogneisses indicate fractional crystallization possibly related to differentiation within a magma chamber. Most of the mafic-ultramafic samples show enrichment of LILE, negative Nb, Ta, P and Ti anomalies, and constant HFSE contents in primitive-mantle normalized trace element plots suggesting volcanic arc affinity probably related to subduction. The enrichment of LREE and flat HREE patterns in chondrite-normalized REE plot, with the Nb-Zr-Y, Y-La-Nb, and Th/Yb-Nb/Yb plots also suggest volcanic arc affinity. The felsic orthogneiss plotted on Nb/Zr-Zr diagram (low Nb/Zr ratio) and spider diagrams (enrichment of LILE, negative Nb, Ta, P and Ti anomalies) also show magmatic arc origin. The morphology, internal structure, and high Th/U ratio of zircon grains in felsic orthogneiss are consistent with magmatic origin for most of these grains. Zircon U-Pb analyses suggest Early Neoproterozoic (847.4 ± 8.0 Ma) magmatism and protolith formation. Some older grains (1026-882 Ma) are regarded as

  14. Alkaline magmatism in the Amambay area, NE Paraguay: The Cerro Sarambí complex

    NASA Astrophysics Data System (ADS)

    Gomes, C. B.; Velázquez, V. F.; Azzone, R. G.; Paula, G. S.

    2011-07-01

    The Early Cretaceous alkaline magmatism in the northeastern region of Paraguay (Amambay Province) is represented by stocks, plugs, dikes, and dike swarms emplaced into Carboniferous to Triassic-Jurassic sediments and Precambrian rocks. This magmatism is tectonically related to the Ponta Porã Arch, a NE-trending structural feature, and has the Cerro Sarambí and Cerro Chiriguelo carbonatite complexes as its most significant expressions. Other alkaline occurrences found in the area are the Cerro Guazú and the small bodies of Cerro Apuá, Arroyo Gasory, Cerro Jhú, Cerro Tayay, and Cerro Teyú. The alkaline rocks comprise ultramafic-mafic, syenitic, and carbonatitic petrographic associations in addition to lithologies of variable composition and texture occurring as dikes; fenites are described in both carbonatite complexes. Alkali feldspar and clinopyroxene, ranging from diopside to aegirine, are the most abundant minerals, with feldspathoids (nepheline, analcime), biotite, and subordinate Ti-rich garnet; minor constituents are Fe-Ti oxides and cancrinite as the main alteration product from nepheline. Chemically, the Amambay silicate rocks are potassic to highly potassic and have miaskitic affinity, with the non-cumulate intrusive types concentrated mainly in the saturated to undersaturated areas in silica syenitic fields. Fine-grained rocks are also of syenitic affiliation or represent more mafic varieties. The carbonatitic rocks consist dominantly of calciocarbonatites. Variation diagrams plotting major and trace elements vs. SiO 2 concentration for the Cerro Sarambí rocks show positive correlations for Al 2O 3, K 2O, and Rb, and negative ones for TiO 2, MgO, Fe 2O 3, CaO, P 2O 5, and Sr, indicating that fractional crystallization played an important role in the formation of the complex. Incompatible elements normalized to primitive mantle display positive spikes for Rb, La, Pb, Sr, and Sm, and negative for Nb-Ta, P, and Ti, as these negative anomalies are

  15. Structural diversity in binuclear complexes of alkaline earth metal ions with 4,6-diacetylresorcinol

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; Khalil, Saied M. E.; Taha, A.; Mahdi, M. A. N.

    2012-11-01

    A new series of binuclear and mixed-ligand complexes with the general formula: [M 2(LO)yClz]; where M = Mg(II), Ca(II), Sr(II) and Ba(II); H2L = 4,6-diacetylresorcinol, the secondary ligand L' = acetylacetone (acac), 8-hydroxyquinoline (8-HQ) or 2,2'-bipyridyl (Bipy), n = 0-2, m = 1, 2, x = 0, 1, 2, 4, y = 0, 2, 4, 5 and z = 0-2; have been synthesized. They have been characterized by the analytical and spectral methods (IR, 1H NMR and mass) as well as TGA and molar conductivity measurements. The spectroscopic and conductance data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the basicity of the secondary ligand, through the two phenolic and two carbonyl groups. Binuclear octahedral geometry has been assigned to all of the prepared complexes in various molar ratios 2:2; 2:2:2; 1:2:1 and 1:2:4 (L:M:L'). Molecular orbital calculations were performed for the ligands and their complexes using Hyperchem 7.52 program on the bases of PM3 level and the results were correlated with the experimental data. The ligand and some of its alkaline metal(II) complexes showed antibacterial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  16. Alkaline phosphatase-polyresorcinol complex: characterization and application to seed coating.

    PubMed

    Pilar, María C; Ortega, Natividad; Perez-Mateos, Manuel; Busto, María D

    2009-03-11

    An alkaline phosphatase (EC 3.1.3.1) from Escherichia coli ATCC27257 was immobilized by copolymerization with resorcinol. The phosphatase-polyresorcinol complex synthesized retained about 74% of the original enzymatic activity. The pH and temperature profile of the immobilized and free enzyme revealed a similar behavior. Kinetic parameters were determined: K(m) and K(i) values were 2.44 and 0.423 mM, respectively, for the phosphatase-polyresorcinol complex and 1.07 and 0.069 mM, respectively, for free phosphatase. The thermal and storage stabilities of the immobilized phosphatase were higher than those of the native one. On addition to soil, free enzyme was completely inactivated in 4 days, whereas the phosphatase-polyresorcinol complex was comparatively stable. Barley seed coated with the immobilized enzyme exhibited higher rhizosphere phosphatase activity. Under pot culture conditions, an increase in the soil inorganic phosphorus was detected when the seed was encapsulated with the phosphatase-polyresorcinol complex, and a positive influence on biomass and inorganic phosphorus concentration of shoot was observed.

  17. On the complex structural diffusion of proton holes in nanoconfined alkaline solutions within slit pores

    PubMed Central

    Muñoz-Santiburcio, Daniel; Marx, Dominik

    2016-01-01

    The hydroxide anion OH−(aq) in homogeneous bulk water, that is, the solvated proton hole, is known to feature peculiar properties compared with excess protons solvated therein. In this work, it is disclosed that nanoconfinement of such alkaline aqueous solutions strongly affects the key structural and dynamical properties of OH−(aq) compared with the bulk limit. The combined effect of the preferred hypercoordinated solvation pattern of OH−(aq), its preferred perpendicular orientation relative to the confining surfaces, the pronounced layering of nanoconfined water and the topology of the hydrogen bond network required for proton hole transfer lead to major changes of the charge transport mechanism, in such a way that the proton hole migration mechanism depends exquisitely on the width of the confined space that hosts the water film. Moreover, the anionic Zundel complex, which is of transient nature in homogeneous bulk solutions, can be dynamically trapped as a shallow intermediate species by suitable nanoconfinement conditions. PMID:27550616

  18. The alkaline and alkaline-carbonatite magmatism from Southern Brazil

    NASA Astrophysics Data System (ADS)

    Ruberti, E.; Gomes, C. D. B.; Comin-Chiaramonti, P.

    2015-12-01

    Early to Late Cretaceous lasting to Paleocene alkaline magmatism from southern Brazil is found associated with major extensional structural features in and around the Paraná Basin and grouped into various provinces on the basis of several data. Magmatism is variable in size, mode of occurrence and composition. The alkaline rocks are dominantly potassic, a few occurrences showing sodic affinity. The more abundant silicate rocks are evolved undersaturated to saturated in silica syenites, displaying large variation in igneous forms. Less evolved types are restricted to subvolcanic environments and outcrops of effusive suites occur rarely. Cumulatic mafic and ultramafic rock types are very common, particularly in the alkali-carbonatitic complexes. Carbonatite bodies are represented by Ca-carbonatites and Mg-carbonatites and more scarcely by Fe-carbonatites. Available radiometric ages for the alkaline rocks fit on three main chronological groups: around 130 Ma, subcoveal with the Early Cretaceous flood tholeiites of the Paraná Basin, 100-110 Ma and 80-90 Ma (Late Cretaceous). The alkaline magmatism also extends into Paleocene times, as indicated by ages from some volcanic lavas. Geochemically, alkaline potassic and sodic rock types are distinguished by their negative and positive Nb-Ta anomalies, respectively. Negative spikes in Nb-Ta are also a feature common to the associated tholeiitic rocks. Sr-Nd-Pb systematics confirm the contribution of both HIMU and EMI mantle components in the formation of the alkaline rocks. Notably, Early and Late Cretaceous carbonatites have the same isotopic Sr-Nd initial ratios of the associated alkaline rocks. C-O isotopic Sr-Nd isotopic ratios indicate typical mantle signature for some carbonatites and the influence of post-magmatic processes in others. Immiscibility of liquids of phonolitic composition, derived from mafic alkaline parental magmas, has been responsible for the origin of the carbonatites. Close association of alkaline

  19. Xenoliths of mafic/ultramafic igneous rocks as carriers of information on lower crust beneath Złotoryja - Jawor volcanic complex (SW Poland).

    NASA Astrophysics Data System (ADS)

    Dajek, Michał; Matusiak-Malek, Magdalena; Puziewicz, Jacek; Lipa, Danuta; Ntaflos, Theodors

    2016-04-01

    The Cenozoic alkaline volcanic rocks in Lower Silesia (SW Poland) are known for their mantle peridotite xenoliths. However, the mafic and ultramafic xenoliths with cumulative textures and of composition of olivine- or hornblende clinopyroxenite, clinopyroxenite, websterite, norite and gabbro occur in some of the lavas (6 sites) of the Złotoryja-Jawor volcanic complex. The xenoliths are anhydrous, only in Wilcza Góra minor amount of amphibole occurs. The Mg# of clinopyroxene varies from 0.54 (Ostrzyca Proboszczowicka clinopyroxenite) to 0.89 (Góra Świątek clinopyroxenite). Forsterite content in olivine varies from 64% (Winna Góra gabbro) to 86% (Wilcza Góra hornblende clinopyroxenite). Anortite content in plagioclase in nortite and gabbros is 33-56%. The Mg# in amphibole is 0.43 to 0.76. Clinopyroxene trace element composition is typically LREE enriched, but in Wilcza Góra norite and Mnisza Góra clinopyroxenite it is LREE-depleted. The calculated pressures of clinopyroxene crystallization (calculated by the algorithm of Nimis and Ulmer, 1998, CMP, 1998, 122-135, assuming all Fe to be 2+) is from 0.45 to 0.96 GPa pointing to crystallization of the pyroxenitic rocks in lower crust or at crust/mantle boundary. Theoretical melts in equilibrium with clinopyroxene enriched in LREE resemble the alkaline lavas from the area and we suggest they are cognate with host magmas. We explain variations in composition of mafic xenoliths from Wilcza Góra, Winna Góra and Grodziec to be a result of magma fractionation. Xenoliths containing clinopyroxene impoverished in LREE may represent lithologies inherited from Variscan oceanic crust. Megacrysts of clinopyroxene present in some of the localities cannot result from disintegration of mafic xenoliths This study was possible thanks to project NCN UMO-2014/15/B/ST10/00095 of Polish National Centre for Science.

  20. Geology is the Key to Explain Igneous Activity in the Mediterranean Area

    NASA Astrophysics Data System (ADS)

    Lustrino, M.

    2014-12-01

    Igneous activity in tectonically complex areas can be interpreted in many different ways, producing completely different petrogenetic models. Processes such as oceanic and continental subduction, lithospheric delamination, changes in subduction polarity, slab break-off and mantle plumes have all been advocated as causes for changes in plate boundaries and magma production, including rate and temporal distribution, in the circum-Mediterranean area. This region thus provides a natural laboratory to investigate a range of geodynamic and magmatic processes. Although many petrologic and tectonic models have been proposed, a number of highly controversial questions still remain. No consensus has yet been reached about the capacity of plate-tectonic processes to explain the origin and style of the magmatism. Similarly, there is still not consensus on the ability of geochemical and petrological arguments to reveal the geodynamic evolution of the area. The wide range of chemical and mineralogical magma compositions produced within and around the Mediterranean, from carbonatites to strongly silica-undersaturated silico-carbonatites and melilitites to strongly silica-oversaturated rhyolites, complicate models and usually require a large number of unconstrained assumptions. Can the calcalkaline-sodic alkaline transition be related to any common petrogenetic point? Is igneous activity plate-tectonic- (top-down) or deep-mantle-controlled (bottom-up)? Do the rare carbonatites and carbonate-rich igneous rocks derive from the deep mantle or a normal, CO2-bearing upper mantle? Do ultrapotassic compositions require continental subduction? Understanding chemically complex magmas emplaced in tectonically complex areas require open minds, and avoiding dogma and assumptions. Studying the geology and shallow dynamics, not speculating about the deep lower mantle, is the key to understanding the igneous activity.

  1. Petrology and geochronology of Xuejiashiliang igneous complex and their genetic link to the lithospheric thinning during the Yanshanian orogenesis in eastern China

    NASA Astrophysics Data System (ADS)

    Su, Shangguo; Niu, Yaoling; Deng, Jinfu; Liu, Cui; Zhao, Guochun; Zhao, Xingguo

    2007-06-01

    The Xuejiashiliang igneous complex, ˜ 150 km north of the City of Beijing, is an important member of the Mesozoic Yanshanian orogen in eastern China. This complex consists of gabbro, monzogabbro, monzonite, syenite and granite. In situ zircon U/Pb dating shows that the Xuejiashiliang complex was emplaced at ˜ 128.8-123.7 Ma (i.e., K 11). Field and petrographic observations together with bulk-rock major element, trace element and Sr-Nd-Pb isotopic data suggest that the gabbro represent remnants of a mafic intrusion formed from cooling of a mantle derived melt that underplated beneath or intruded into the lower crust. The monzogabbro may be the product of deep crustal assimilation of this mantle derived melt. The syenite may have precipitated from a melt produced by deep crustal melting caused by the mantle derived melt. The monzonite may have formed from mixing between melts parental to the syenite and monzogabbro. That is, all these diverse lithologies may have resulted from varying degrees of mantle melt induced crustal melting, melt assimilation, differentiation and mixing. The granite is best interpreted as resulting from upper crustal melting and advanced degrees of differentiation. The remarkably similar Nb-Sr-Pb isotopes of all these lithologies (except for 87Sr/ 86Sr of the granite) with an "EM1-like" signature point to a common source they share. This common source could be ancient lithospheric mantle, but we consider the Archean lower crust to be the more likely candidate. The high 87Sr/ 86Sr (0.8955) of the granite resulted from radiogenic ingrowth of 87Sr due to the elevated Rb/Sr ratio (˜ 22.4). The high [La/Yb] CN and Sr/Y ratios of all these lithologies (except the granite) are consistent with magma genes at depths where garnet is a stable phase. This is consistent with the condition of syenite genes that requires pressures equivalent to depths in excess of 50 km. All these constrain that the complex may have formed at the base of the thickened

  2. Draped aeromagnetic survey in Transantarctic Mountains over the area of the Butcher Ridge igneous complex showing extent of underlying mafic intrusion

    USGS Publications Warehouse

    Behrendt, John C.; Damaske, D.; Finn, C.A.; Kyle, P.; Wilson, T.J.

    2002-01-01

    A draped aeromagnetic survey over the area surrounding the Butcher Ridge igneous complex (BRIC), Transantarctic Mountains, was acquired in 1997-1998 as part of a larger Transantarctic Mountains Aerogeophysical Research Activity survey. The BRIC is a sill-like hypoabyssal intrusion ranging in composition from tholeiitic basalt to rhyolite. An 40Ar/39 Ar age of 174 Ma and the chemical character of the basaltic rocks show the BRIC to be part of the widespread Jurassic Ferrar suite of continental tholeiitic rocks, that extends for 3500 km across Antarctica. The aeromagnetic survey shows a horseshoe-shaped pattern of anomalies reaching amplitudes as great as 1900 nT generally associated with the bedrock topography where it is exposed. It is apparent that the high-amplitude anomaly pattern is more extensive than the 10-km-long exposed outcrop, first crossed by a single 1990 aeromagnetic profile. The highest-amplitude anomalies appear south of the profile acquired in 1990 and extend out of the survey area. The new aeromagnetic data allow determination of the extent of the interpreted Butcher mafic(?) intrusion beneath exposures of Beacon sedimentary rock and ice in the area covered, as well as beneath the small BRIC exposure. The magnetic anomalies show a minimum area of 3000 km2, a much greater extent than previously inferred. Magnetic models indicate a minimum thickness of ~1-2 km for a horizontal intrusion. However, nonunique models with magnetic layers decreasing in apparent susceptibility with depth are consistent with of a 4- to 8-km-thick layered intrusion. These magnetic models indicate progressively deeper erosion of the interpreted mafic-layered body from the south to north. The erosion has removed more magnetic upper layers that mask the magnetic effects of the lower less magnetic layers. The probable minimum volume of the intrusion in the area of the survey is ~6000 km3. An alternate, but less likely, interpretation of a series of dikes can also fit the

  3. Magnetotelluric investigation of the Alnö alkaline and carbonatite ring complex, central Sweden

    NASA Astrophysics Data System (ADS)

    Yan, Ping; Andersson, Magnus; Garcia Juanatey, Maria A.; Shan, Chunling; Malehmir, Alireza; Pedersen, Laust B.

    2014-05-01

    Alnö complex, 553-590 Ma, located in central Sweden, is one of the largest of few known alkaline and carbonatite ring intrusions in the world. The complex primarily consists of alkaline silicate rocks (ijolite, nepheline-syenite and pyroxenite) and a wide range of carbonatite dykes with different compositions (e.g., sövite). To better understand the intrusion mechanism(s) and the deeper structure of the intrusion, three high-resolution reflection seismic, gravity and magnetic profiles, crossing the main intrusion, were acquired in winter 2010. Together with these, petrophysical measurements on various rock samples have also been carried out. These data not only successfully showed the lateral extension of the intrusion at depth but also suggested a solidified saucer-shaped magma chamber at about 3 km depth that is associated with caldera-related ring-type fault systems. To further elucidate these interpretations, magnetotelluric (MT) data were acquired in summer 2013. The MT data were measured at 34 stations across the intrusion and designed so that a 3D conductivity model can be obtained. Most of the sites are located along the seismic profiles, while the rest is distributed over the intrusion area, to provide lateral and off-profile information. The time series were recorded with four broadband MT instruments simultaneously. The used sampling rates were 1000 Hz (two hours after midnight) and 20 Hz (a full day). The collected MT data are highly influenced by noise from cultural sources. Luckily, higher frequencies are less influenced providing a good coverage of the interest depth of about 5 km. Therefore, the data processing and analysis focused solely on the high frequency data. To decrease the effect of noise, the best quality site in one day was chosen for remote referencing the other three. Even if the sites were only 500 to 1000 m apart, better results were obtained, indicating very localized noise sources in the area. The strike analysis of the obtained

  4. Petrogenesis of the Sabongari alkaline complex, cameroon line (central Africa): Preliminary petrological and geochemical constraints

    NASA Astrophysics Data System (ADS)

    Njonfang, Emmanuel; Tchoneng, Gilbert Tchuenté; Cozzupoli, Domenico; Lucci, Federico

    2013-07-01

    The petrography, mineral chemistry and geochemical features of the Sabongari alkaline complex are presented and discussed in this paper with the aim of constraining its petrogenesis and comparing it with other alkaline complexes of the Cameroon Line. The complex is mainly made up of felsic rocks: (i) granites predominate and include pyroxene-amphibole (the most abundant), amphibole-biotite, biotite and pyroxene types; (ii) syenites are subordinate and comprise amphibole-pyroxene and amphibole-biotite quartz syenites; (iii) pyroxene-amphibole-biotite trachyte and (iv) relatively abundant rhyolite. The minor basic and intermediate terms associated with felsic rocks consist of basanites, microdiorite and monzodioites. Two groups of pyroxene bearing rocks are distinguished: a basanite-trachyte-granite (Group 1) bimodal series (SiO2 gap: 44 and 63 wt.%) and a basanite-microdiorite-monzodiorite-syenite-granite (Group 2) less pronounced bimodal series (reduced SiO2 gap: 56-67 wt.%). Both are metaluminous to peralkaline whereas felsic rocks bare of pyroxene (Group 3) are metaluminous to peraluminous. The Group 1 basanite is SiO2-undersaturated (modal analcite in the groundmass and 11.04 wt.% normative nepheline); its Ni (240 ppm) and Cr (450 ppm) contents, near mantle values, indicate its most primitive character. The Group 2 basanite is rather slightly SiO2-saturated (1.56 wt.% normative hypersthene), a marker of its high crustal contamination (low Nb/Y-high Rb/Y). The La/Yb and Gd/Yb values of both basanites (1: 19.47 and 2.92; 2: 9.09 and 2.23) suggest their common parental magma composition, and their crystallization through two episodes of partial melting (2% and 3% respectively) of a lherzolite mantle source with <4% residual garnet. The effects of crustal contamination were selectively felt in the values of HFSE/LREE, LREE/LILE and LREE/HFSE ratios, known as indicators. Similar features have been recently obtained in the felsic lavas of the Cameroon Volcanic Line.

  5. Mercury(II) Complex Formation With Glutathione in Alkaline Aqueous Solution

    SciTech Connect

    Mah, V.; Jalilehvand, F.

    2009-05-19

    The structure and speciation of the complexes formed between mercury(II) ions and glutathione (GSH = L-glutamyl-L-cysteinyl-glycine) have been studied for a series of alkaline aqueous solutions (C{sub Hg{sup 2+}} {approx} 18 mmol dm{sup -3} and C{sub GSH} = 40-200 mmol dm{sup -3} at pH {approx} 10.5) by means of extended X-ray absorption fine structure (EXAFS) and {sup 199}Hg NMR spectroscopy at ambient temperature. The dominant complexes are [Hg(GS){sub 2}]{sup 4-} and [Hg(GS){sub 3}]{sup 7-}, with mean Hg-S bond distances of 2.32(1) and 2.42(2) {angstrom} observed in digonal and trigonal Hg-S coordination, respectively. The proportions of the Hg{sup 2+}-glutathione complexes were evaluated by fitting linear combinations of model EXAFS oscillations representing each species to the experimental EXAFS spectra. The [Hg(GS){sub 4}]{sup 10-} complex, with four sulfur atoms coordinated at a mean Hg-S bond distance of 2.52(2) {angstrom}, is present in minor amounts (<30%) in solutions containing a large excess of glutathione (C{sub GSH} {ge} 160 mmol dm{sup -3}). Comparable alkaline mercury(II) cysteine (H{sub 2}Cys) solutions were also investigated and a reduced tendency to form higher complexes was observed, because the deprotonated amino group of Cys{sup 2-} allows the stable [Hg(S,N-Cys){sub 2}]{sup 2-} chelate to form. The effect of temperature on the distribution of the Hg{sup 2+}-glutathione complexes was studied by comparing the EXAFS spectra at ambient temperature and at 25 K of a series of glycerol/water (33/67, v/v) frozen glasses with and C{sub Hg{sup 2+}} {approx} 7 mmol dm{sup -3} and C{sub GSH} = 16-81 mmol dm{sup -3}. Complexes with high Hg-S coordination numbers, [Hg(GS){sub 3}]{sup 7-} and [Hg(GS){sub 4}]{sup 10-}, became strongly favored when just a moderate excess of glutathione (C{sub GSH} {ge} 28 mmol dm{sup -3}) was used in the glassy samples, as expected for a stepwise exothermic bond formation. Addition of glycerol had no effect on the Hg

  6. Late Triassic alkaline complex in Sulu UHP terrane: Implications for post-collisional magmatism along the continental subduction zone

    NASA Astrophysics Data System (ADS)

    Xu, H.; Song, Y.; Liu, Q.

    2014-12-01

    In order to insight into crust-mantle interaction triggered by partial melting of the subudcted continental crust during its exhumation, we carried out a combined study on Shidao alkaline complex in the Sulu ultrahigh pressure (UHP) terrane. The alkaline complex is composed of shoshonitic to ultrapotassic gabbro, pyroxene syenite, amphibole syenite, quartz syenite, and granite. Field researches suggest that the mafic rocks are earlier than the felsic ones in sequence. LA-ICPMS zircon U-Pb dating on them gives Late Triassic ages of 214 ± 2 to 200 ± 3 Ma from mafic to felsic rocks. These ages are a bit younger than Late Triassic ages for partial melting of the Sulu UHP terrane during exhumation, indicating syn-exhumation magmatism during continental collision. The alkaline rocks have wide ranges of SiO2 (49.7 - 76.7 wt.%), MgO (8.25 - 0.03 wt.%),total Fe2O3 (9.23 - 0.47 wt.%), CaO (8.39 - 0.39 wt.%), Ni (126.0 - 0.07 ppm), and Cr (182.0 - 0.45 ppm) contents. Other major oxides are regularly changed with SiO2. The alkaline rocks have characteristics of arc-like patterns in the trace element distribution, e.g., enrichment of LREE and LILE (Rb, Ba, Th and U), depletion of HFSE (Nb, Ta, P and Ti), and positive Pb anomalies. From the mafic to felsic rocks, (La/Yb)N ratios and contents of the total REE, Sr and Ba are decreased but Rb contents are increased. The alkaline rocks also display features of A2-type granitoids, suggesting a post-collisional magmatism. They have high initial 87Sr/86Sr ratios (0.70575 and 0.70927) and negative ɛNd(t) values (-18.6 to -15.0) for whole-rock. The homogeneous initial 87Sr/86Sr ratios and ɛNd(t) values of the alkaline rocks are almost unchanged with SiO2 and MgO contents, suggesting a fractional crystallization (FC) process from a same parental magma. Our studies suggest a series of crust-mantle interaction processes along the continental subduction interface as follows: (1) melts from partial melting of the subducted continental

  7. Subduction- and non-subduction-related igneous rocks in the Central European Variscides: geochemical and Nd isotope evidence from the Kłodzko Metamorphic Complex, Polish Sudetes

    NASA Astrophysics Data System (ADS)

    Kryza, Ryszard; Mazur, Stanisław; Pin, Christian

    2003-11-01

    The Kłodzko Metamorphic Complex (KMC) in the Central Sudetes is a composite outcrop of pre-Upper Devonian metasedimentary and metaigneous rocks, formed of several thrust units. The metaigneous rocks are geochemically diversified, and were interpreted to reflect a complex geodynamic setting of emplacement. The association of large amounts of felsic and mafic rocks is reminiscent of the model of Cambro-Ordovician bimodal, rift-related suites developed along the northern periphery of Gondwana. However, the felsic rocks are potash-poor, calc-alkaline in character, while the associated mafic rocks are, in part, metagabbros and cumulates resembling N-MORB, which is consistent with neither typical ensialic rift nor evolved MOR tectonic environments. Combined with published data, our new geochemical and Nd isotope results show that the metabasic rocks of the northeastern part of the KMC, not associated with felsic volcanics, are of within-plate type, with an ɛNd 400 (assuming approximate youngest possible Silurian/Devonian age) of +6.8, typical of magmas derived from time-integrated depleted mantle sources. The metagabbros of the southwestern part of the KMC (associated with felsic rocks) range from slightly enriched to depleted rocks, and their ɛNd 560 (assuming a Neoproterozoic age, K. Turniak, personal communication) scatters from +2.2 to +8.6, suggesting that hybrid sources and/or variable degrees of crustal contamination of a strongly depleted mantle source were involved. The intermediate and acidic rocks are peraluminous to metaluminous rhyolites, rhyodatites/dacites, and andesites (and volcaniclastics), with Na 2O > K 2O and large negative anomalies of Nb, Sr, and Ti. Their highly variable, but distinctly positive, ɛNd 560 values (from +2.9 to +8.6, mostly clustered around +5.5) overlap those measured in the associated metagabbros, thereby substantiating close genetic relationships. Metarhyolites produced by crustal melting are conspicuously missing. A

  8. Sensitive and selective colorimetric assay of alkaline phosphatase activity with Cu(II)-phenanthroline complex.

    PubMed

    Hu, Qiong; He, Minhui; Mei, Yaqi; Feng, Wenjie; Jing, Su; Kong, Jinming; Zhang, Xueji

    2017-01-15

    Alkaline phosphatase (ALP) plays a vital role in dephosphorylation- and phosphorylation-related cellular regulation and signaling processes. Accordingly, the development of efficient methods for ALP activity assay is of significant importance in clinical diagnosis. In this work, a simple and practical method is reported for the first time for the sensitive and selective colorimetric assay of ALP activity by exploiting a water-soluble Cu(II)-phenanthroline complex as the probe, on the basis of the distinctive metal-to-ligand charge-transfer (MLCT) properties. This method is simply built on a two-step chromogenic reaction: the enzymatic hydrolysis of the substrate ascorbic acid 2-phosphate to ascorbic acid (AA), followed by the reduction of the colorimetric probe Cu(BPDS)2(2-) (BPDS=bathophenanthroline disulfonate) by AA to its cuprous form. The latter process triggers a turn-on spectral absorption at 424nm and a striking color change of the solution from colorless to blackish-green. Needless of complicated protocols and instrumentation, this method allows a sensitive readout of ALP activity within a wide linear range of 0-200mUmL(-)(1), with a detection limit down to 1.25mUmL(-1). Results also reveal that it is highly selective and holds great potential in ALP inhibitor efficiency evaluation. In addition, quantitative analysis of ALP activity in spiked serum samples has been realized successfully in the linear range of 0-200mUmL(-1), with a detection limit of 1.75mUmL(-1). Advantages of simplicity, wide linear range, high sensitivity and selectivity, low cost, and little background interference render this method great potential in practical applications.

  9. High crystallization temperatures indicated for igneous rocks from tranquillity base.

    PubMed

    Skinner, B J

    1970-01-30

    Complex intergrowths of troilite (FeS) and iron in the igneous rocks from Tranquillity Base contain 8.4 percent native iron by volume. The intergrowths were derived from an initially homogeneous sulfide liquid that separated immiscibly from the magma at 1140 degrees C or above. Textures show that the sulfide liquid formed late in the crystallization and cooling history of the igneous rocks and after the major ilmenite and pyroxene had formed.

  10. Tertiary alkaline Roztoky Intrusive Complex, České středohoří Mts., Czech Republic: petrogenetic characteristics

    NASA Astrophysics Data System (ADS)

    Skála, Roman; Ulrych, Jaromír; Ackerman, Lukáš; Jelínek, Emil; Dostál, Jaroslav; Hegner, Ernst; Řanda, Zdeněk

    2014-07-01

    The České středohoří Mts. is the dominant volcanic center of the Ohře (Eger) rift zone. It hosts the Roztoky Intrusive Complex (RIC), which is made up of a caldera vent and intrusions of 33-28-Ma-old hypabyssal bodies of essexite-monzodiorite-sodalite syenite series accompanied by a radially oriented 30-25-Ma-old dike swarm comprising about 1,000 dikes. The hypabyssal rocks are mildly alkaline mostly foid-bearing types of mafic to intermediate compositions. The dike swarm consists of chemically mildly alkaline and rare strongly alkaline rocks (tinguaites). The geochemical signatures of the mildly alkaline hypabyssal and associated dike rocks of the RIC are consistent with HIMU mantle sources and contributions from lithospheric mantle. The compositional variations of essexite and monzodiorite can be best explained by fractional crystallization of parent magma without significant contributions of crustal material. On the other hand, the composition of monzosyenite, leuco-monzodiorite and sodalite syenite reflects fractional crystallization coupled with variable degrees of crustal assimilation. It is suggested that the parent magmas in the Ohře rift were produced by an adiabatic decompression melting of ambient upper mantle in response to lithospheric extension associated with the Alpine Orogeny.

  11. Remote mineralogic and lithologic mapping of the Ice River alkaline complex, British Columbia, Canada, using AVIRIS data

    USGS Publications Warehouse

    Bowers, T.L.; Rowan, L.C.

    1996-01-01

    The Ice River Alkaline Complex is a late Paleozoic intrusion of mafic alkaline rocks, syenite, and carbonatite exposed in southeastern British Columbia, Canada. The complex intrudes Cambrian and Ordovician shales, slates, and limestones of the Chancellor and Ottertail Formations and the McKay Group. We examined the alkaline complex and adjacent country rocks using Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) data. The data were first calibrated to relative reflectance and then used to spectrally map mineralogies in the study area by using a linear spectral unmixing program. This technique models each pixel spectrum in an AVIRIS image as a linear combination of unique endmember spectra. We selected endmember spectra from well-exposed and spectrally distinct mineralogic units, vegetation, and snow. Four of the endmembers reflect mineralogic variations within the McKay group in the study area, and may represent lateral and vertical variations of sedimentary or metamorphic facies. Otherwise, the resultant spatial distribution of endmembers shows generally close agreement with the published geologic map, although, in several places, our image-map is more accurate than the published map.

  12. Primary alkaline magmas associated with the Quaternary Alligator Lake volcanic complex, Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Eiché, G. E.; Francis, D. M.; Ludden, J. N.

    1987-02-01

    The Alligator Lake complex is a Quaternary alkaline volcanic center located in the southern Yukon Territory of Canada. It comprises two cinder cones which cap a shield consisting of five distinct lava units of basaltic composition. Units 2 and 3 of this shield are primitive olivine-phyric lavas (13.5 19.5 cation % Mg) which host abundant spinel lherzolite xenoliths, megacrysts, and granitoid fragments. Although the two lava types have erupted coevally from adjacent vents and are petrographically similar, they are chemically distinct. Unit 2 lavas have considerably higher abundances of LREE, LILE, and Fe, but lower HREE, Y, Ca, Si, and Al relative to unit 3 lavas. The 87Sr/86Sr and 143Nd/144Nd isotopic ratios of these two units are, however, indistinguishable. The differences between these two lava types cannot be explained in terms of low pressure olivine fractionation, and the low concentrations of Sr, Nb, P, and Ti in the granitoid xenoliths relative to the primitive lavas discounts differential crustal contamination. The abundance of spinel lherzolite xenoliths and the high Mg contents in the lavas of both units indicates that their compositional differences originated in the upper mantle. The Al and Si systematics of these lavas suggests that, compared to unit 3 magmas, the unit 2 magmas may have segregated at greater depths from a garnet lherzolite mantle. The identical isotopic composition and similar ratios of highly incompatible elements in these two lava units argues against their differences being a consequence of random metasomatism or mantle heterogeneity. The lower Y and HREE contents but higher concentrations of incompatible elements in the unit 2 lavas relative to unit 3 can be most simply explained by differential partial melting of similar garnet-bearing sources. The unit 2 magmas thus appear to have been generated by smaller degrees of melting at a greater depth than the unit 3 magmas. The contemporaneous eruption of two distinct but

  13. Origins of Igneous Layering

    NASA Astrophysics Data System (ADS)

    Marsh, Bruce

    Anyone who has ever seen a photo of a layered intrusion, let alone visited one first hand, or even seen a thin section from one, cannot help but be impressed by the stunning record of crystal growth and deposition. Such bodies stand as majestic monuments of undeniable evidence that intricate magmatic processes exist, processes that couple crystallization, convection, and crystal sorting to form rocks so highly ordered and beautiful that they are a wonder to behold. These are the altars to which petrologists must carry their conceived petrologic processes for approval.Although significant in number, the best layered intrusions seem to be found almost always in remote places. Their names, Bushveld, Muskox, Kiglapait, Stillwater, Duke Island, Skaergaard, Rhum, ring through igneous petrology almost as historic military battles (Saratoga, Antietam, Bull Run, Manassas, Gettysburg) do through American history. People who have worked on such bodies are almost folk heros: Wager, Deer, Brown, Jackson, Hess, Irvine, McBirney, Morse; these names are petrologic household words. Yet with all this fanfare and reverence, layered instrusions are nearly thought of as period pieces, extreme examples of what can happen, but not generally what does. This is now all changing with the increasing realization that these bodies are perhaps highly representative of all magmatic bodies. They are simply more dynamically complete, containing more of the full range of interactions, and of course, exposing a more complete record. They are one end of a spectrum containing lava flows, lava lakes, large sills, plutons, and layered intrusions. This book uniquely covers this range with an abundance of first-hand field observations and a good dose of process conceptualization, magma physics, and crystal growth kinetics.

  14. Spatiotemporal reconstruction of Late Mesozoic silicic large igneous province and related epithermal mineralization in South China: Insights from the Zhilingtou volcanic-intrusive complex

    NASA Astrophysics Data System (ADS)

    Wang, Guo-Guang; Ni, Pei; Zhao, Chao; Wang, Xiao-Lei; Li, Pengfei; Chen, Hui; Zhu, An-Dong; Li, Li

    2016-11-01

    Silicic large igneous provinces (SLIPs) generally reflect large-scale melting of lower crustal materials and represent significant metal reservoirs. The South China Block-Coastal Region (SCB-CR) SLIP hosts several large epithermal deposits. To better understand these deposits, we document the spatiotemporal framework of the host SLIP across the SCB-CR. Using zircon U-Pb dating and geochemical and isotopic analysis, we identify four stages of emplacement. Stage 1 felsophyre (circa 149 Ma) shows a chemical affinity to highly fractionated I-type granites. Stages 2 and 3 of low-Mg felsic volcanics (circa 128 to 111 Ma) and stage 4 felsite (circa 100 Ma) have higher ɛHf(t) and ɛNd(t) values than stage 1 felsophyre, suggesting a significant contribution of newly underplated juvenile crust to the magma sources. Stage 4 diabase (circa 101 Ma) was likely produced by melting of subduction˗metasomatized asthenospheric mantle. Together with reliable published data, we build a new spatiotemporal framework of volcanics and infer that the majority of the SCB-CR SLIP was related to the gradual northwestward subduction of the Izanagi plate beneath South China in a continental arc setting during circa 170 to 110 Ma, and minor contribution was from the eastward retreat of the subducting slab in a back-arc setting during circa 110 to 90 Ma. We conclude that the large-scale epithermal mineralization was generated by melting of the metal-rich, thin (30-40 km), newly underplated hydrous juvenile crust during the tectonic transition from arc to back-arc settings.

  15. Mesozoic igneous intrusions in New England and Quebec: Implications from lead (Pb) isotopes on petrogenesis and mantle sources (Ascutney Mountain, Vermont; Mont Saint Hilaire, Quebec; Pliny Complex, New Hampshire)

    SciTech Connect

    Schucker, D.E.

    1992-01-01

    Lead isotopes are used to study Mesozoic intrusions from New England and Quebec, specifically the igneous complexes of Ascutney Mountain (Vermont), Mont Saint Hilaire (Quebec), and Pliny (New Hampshire). The main objectives are to address the: (1) petrogenesis of specific complexes using Pb isotopes along with previous results; and (2) sources of parental magmas in the context of a possible plume source for the Cretaceous intrusions and New England Seamounts. Analytical procedures for Pb and U are also described in detail. For each of the three complexes, significant variation in apparent initial [sup 208]Pb/[sup 204]Pb, [sup 207]Pb/[sup 204]Pb, and [sup 206]Pb/[sup 204]Pb ratios are observed. These variations reflect crustal contamination and local country rocks are isotopically suitable contaminants. Contamination lowers the Pb isotopic ratios of the modified magmas. The Pb ratios of the parental magmas are constrained by defining trends resulting from crustal contamination. At the Ascutney complex, granites appear to be uniform at the time of formation based on feldspar results. Granite whole rocks exhibit open system U-Pb behavior which is attributed to significant recent U loss (of up to 38%). Both local schists and gneisses are important contaminants with generally <25% contamination. Significant isotopic variations are apparent at Mont Saint Hilaire where rock-feldspar variations are apparently not in isotopic equilibrium. Feldspars reflect magmatic values and indicate crustal contamination of a parental magma for the Hilaire complex. A limited data set for the Pliny complex suggests a parental magma. The Pb results support a common mantle source for the Cretaceous continental intrusions (Ascutney and Mont Saint Hilaire) and the New England Seamounts. They imply magma from a sublithospheric mantle-plume, and that magmas ascended with little or no lithospheric interaction. The magma source for the Jurassic Pliny complex appears to be different.

  16. Petrology of the igneous rocks

    NASA Technical Reports Server (NTRS)

    Mccallum, I. S.

    1987-01-01

    Papers published during the 1983-1986 period on the petrology and geochemistry of igneous rocks are discussed, with emphasis on tectonic environment. Consideration is given to oceanic rocks, subdivided into divergent margin suites (mid-ocean ridge basalts, ridge-related seamounts, and back-arc basin basalts) and intraplate suites (oceanic island basalts and nonridge seamounts), and to igneous rocks formed at convergent margins (island arc and continental arc suites), subdivided into volcanic associations and plutonic associations. Other rock groups discussed include continental flood basalts, layered mafic intrusions, continental alkalic associations, komatiites, ophiolites, ash-flow tuffs, anorthosites, and mantle xenoliths.

  17. Temperature-induced collapse of alkaline Earth cation-polyacrylate anion complexes.

    PubMed

    Lages, Sebastian; Schweins, Ralf; Huber, Klaus

    2007-09-06

    Polyacrylate anions are used to inhibit CaCO3 precipitation and may be a promising additive to control formation of inorganic nanoparticles. The origin of this applicability lies in specific interactions between the alkaline earth cations and the carboxylate functions along the polyacrylate chains. In the absence of CO32- anions, these interactions eventually cause precipitation of polyelectrolytes. Extended investigation of dilute sodium polyacrylate solutions approaching this precipitation threshold revealed a dramatic shrinking of the PA coil dimensions once the threshold is reached (Eur. Phys. J. E 2001, 5, 117). Recent isothermal calorimetric titration experiments by Antonietti et al. (Macromolecules 2004, 37, 3444) indicated that the driving force of this precipitation is entropic in nature. In the present work, we investigated the impact of temperature on the structural changes of dissolved polyacrylate chains decorated with alkaline earth cations. To this end, large polyacrylate chains were brought close to the precipitation threshold by the addition of distinct amounts of Ca2+ or Sr2+ cations. The resulting structural intermediates were then subjected to temperature variations in the range of 15 degrees C

  18. Determination of the equilibrium formation constants of two U(VI)-peroxide complexes at alkaline pH.

    PubMed

    Meca, S; Martínez-Torrents, A; Martí, V; Giménez, J; Casas, I; de Pablo, J

    2011-08-21

    The formation of uranyl-peroxide complexes was studied at alkaline media by using UV-Visible spectrophotometry and the STAR code. Two different complexes were found at a H(2)O(2)/U(VI) ratio lower than 2. A graphical method was used in order to obtain the formation constants of such complexes and the STAR program was used to refine the formation constants values because of its capacity to treat multiwavelength absorbance data and refining equilibrium constants. The values obtained for the two complexes identified were: UO(2)(2+) + H(2)O(2) + 4OH(-) <−> UO(2)(O(2))(OH)(2)(2-) + 2H(2)O: log β°(1,1,4) = 28.1 ± 0.1 (1). UO(2)(2+) + 2H(2)O(2) + 6OH(-) <−> UO(2)(O(2))(2)(OH)(2)(4-) + 4H(2)O: log β°(1,2,6) = 36.8 ± 0.2 (2). At hydrogen peroxide concentrations higher than 10(-5) mol dm(-3), and in the absence of carbonate, the UO(2)(O(2))(2)(OH)(2)(4-) complex is predominant in solution, indicating the significant peroxide affinity of peroxide ions for uranium and the strong complexes of uranium(VI) with peroxide.

  19. Ionium dating of igneous rocks.

    PubMed

    Kigoshi, K

    1967-05-19

    Local fractionation of uranium and thorium, between minerals within a sample of igneous rock at the time of crystallization, makes it possible to date its solidification by use of ionium and uranium. Results on samples of granite, pumice, and lava suggest that this method of dating is reliable.

  20. Hydrogen and carbon abundances and isotopic ratios in apatite from alkaline intrusive complexes, with a focus on carbonatites

    SciTech Connect

    Nadeau, S.L.; Epstein, S.; Stolper, E.

    1999-06-01

    The authors report H and C contents and {delta}D and {delta}{sup 13}C values of apatites from 15 alkaline intrusive complexes ranging in age from 110 Ma to 2.6 Ga. Sampling focused on carbonatites, but included silicate rocks as well. Heating temperatures up to 1,500 C is needed to extract fully H{sub 2}O and CO{sub 2} from these apatites. Apatites from carbonatite-rich intrusive complexes contain 0.2--1.1 wt% H{sub 2}O and 0.05--0.70 wt% CO{sub 2}; apatites from two silicate-rich alkaline complexes with little or no carbonatite are generally poorer in both volatile components (0.1--0.2% H{sub 2}O and 0.01--0.11% CO{sub 2}). D/H ratios in apatites from these rocks are bimodally distributed. The authors suggest that the {delta}D values of group I apatites represent primitive, mantle-derived values and that the group II apatites crystallized from degassed magmas, resulting in lower H{sub 2}O contents and {delta}D values. In contrast to H{sub 2}O contents and {delta}D values, CO{sub 2} contents and {delta}{sup 13}C values of gas released at high temperatures from multiple aliquots of these apatite samples are variable. This suggests the presence of more than one C-bearing component in these apatites, one of which is proposed to be dissolved carbonate; the other could be associated with hydrocarbons.

  1. Maltol complexes of vanadium (IV) and (V) regulate in vitro alkaline phosphatase activity and osteoblast-like cell growth.

    PubMed

    Barrio, D A; Braziunas, M D; Etcheverry, S B; Cortizo, A M

    1997-06-01

    Vanadium compounds have been found to possess insulin- and growth factor-mimetic effects. In consequence, these derivatives are potentially useful as effective oral therapeutic agents in diabetic patients. However, their use has been limited by various toxic side-effects and by the low solubility of different derivatives. Recently, vanadium complex with maltol, a sugar used as a common food additive, have been synthesised and investigated in animals, showing possible insulin-mimetic effects with low toxic side-effects. In the present study we have investigated the effect of bis(maltolato)oxovanadium (IV) (BMOV) and bis(maltolato)dioxovanadium (V) (BMV) on bone cells in culture as well as their direct effect on alkaline phosphatase in vitro. A comparison was also made with the action of vanadate and vanadyl cation. Vanadium compounds regulated cell proliferation in a biphasic manner with similar potencies. Osteoblast differentiation, assessed by alkaline phosphatase activity, was found to be dose-dependent, with the inhibitory effect being stronger for vanadate and BMOV than for vanadyl and BMV. All vanadium compounds directly inhibited bovine intestinal ALP with a similar potency. Thus, maltol vanadium derivatives behave in a similar way to vanadate and vanadyl in osteoblast-like UMR 106 cells in culture.

  2. 3D magnetotelluric modelling of the Alnö alkaline and carbonatite ring complex, central Sweden

    NASA Astrophysics Data System (ADS)

    Yan, Ping; Andersson, Magnus; Kalscheuer, Thomas; García Juanatey, María A.; Malehmir, Alireza; Shan, Chunling; Pedersen, Laust B.; Almqvist, Bjarne S. G.

    2016-06-01

    Thirty-four broadband magnetotelluric stations were deployed across the Alnö alkaline and carbonatite ring intrusion in central Sweden. The measurements were designed such that both 2D models along existing seismic profiles and a 3D model can be constructed. Alnö Island and surrounding areas are densely populated and industrialized and in order to reduce the effect of noise, the remote reference technique was utilized in time series processing. Strike and dimensionality analyses together with the induction arrows show that there is no homogeneous regional strike direction in this area. Therefore, only the determinant of the impedance tensor was used for 2D inversion whereas all elements of the impedance tensor were used for 3D inversion. Representative rock samples were collected from existing outcrops and their resistivities were measured in the laboratory to facilitate interpretation of the inversion models. The results from these measurements show that coarse-grained (sövite, white color) and fine-grained (dark color) carbonatites are the most conductive and resistive rock types, respectively. In accordance with the interpretation of the reflection seismic images, the 2D and 3D resistivity models depict the caldera-related ring-type fault system and updoming faulted and fractured systems as major 10-500 Ωm conductors, extending down to about 3 km depth. A central ~ 4000 Ωm resistive unit at about 3 km depth appears to correspond to a solidified fossil magma chamber as speculated from the reflection seismic data and earlier field geological studies.

  3. Igneous Graphite in Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1997-01-01

    Igneous graphite. a rare constituent in terrestrial mafic and ultramafic rocks. occurs in three EH and one EL enstatite chondrite impact-melt breccias as 2-150 Ilm long euhedrallaths. some with pyramidal terminations. In contrast. graphite in most enstatite chondrites exsolved from metallic Fe-Ni as polygonal. rounded or irregular aggregates. Literature data for five EH chondrites on C combusting at high temperatures show that Abee contains the most homogeneous C isotopes (i.e. delta(sup 13)C = -8.1+/-2.1%); in addition. Abee's mean delta(sup l3)C value is the same as the average high-temperature C value for the set of five EH chondrites. This suggests that Abee scavenged C from a plurality of sources on its parent body and homogenized the C during a large-scale melting event. Whereas igneous graphite in terrestrial rocks typically forms at relatively high pressure and only moderately low oxygen fugacity (e.g., approx. 5 kbar. logfO2, approx. -10 at 1200 C ). igneous graphite in asteroidal meteorites formed at much lower pressures and oxygen fugacities.

  4. Unusual evolution of silica-under- and -oversaturated alkaline rocks in the Cenozoic Ambohimirahavavy Complex (Madagascar): Mineralogical and geochemical evidence

    NASA Astrophysics Data System (ADS)

    Estrade, Guillaume; Béziat, Didier; Salvi, Stefano; Tiepolo, Massimo; Paquette, Jean-Louis; Rakotovao, Soatsitohaina

    2014-10-01

    The almost unknown Ambohimirahavavy ring complex in the Cenozoic alkaline province of northwestern Madagascar has recently attracted considerable interest because of the discovery of important rare-metal mineralization. The complex consists of arc-shaped bodies made up of silica-under- and -oversaturated syenites and extremely evolved peralkaline granitic dykes, as well as several mafic to felsic volcanic units, including basalt, phonolite and trachyte, all of which have an alkaline affinity. Uranium-lead zircon ages of 24.2 ± 0.6 Ma and 23.5 ± 6.8 Ma have been obtained for nepheline syenites and peralkaline granitic dykes, respectively, which, together with field data and ages of neighboring complexes, support emplacement controlled by regional lithospheric structures, rather than an evolving hot spot. Whole-rock major and trace-element and Sr-Nd isotopic data for the mafic suite suggest that the parental melt of this complex was generated by low degrees of melting of a metasomatized mantle source with residual amphibole. Fractional crystallization of this alkali basaltic melt likely produced the silica-undersaturated suite. We propose that the silica-oversaturated suite evolved from the undersaturated melt after contamination of the latter by crustal material. Further evolution to peralkaline compositions in both suites is attributed mainly to plagioclase and alkali feldspar segregation. Nepheline and feldspar compositions, as well as considerations of mineral equilibria among mafic silicates and Fe-Ti oxide minerals indicate crystallization temperatures of 1000 to 700 °C and an oxygen fugacity of 0.4 to 0.8 log units below the fayalite-magnetite-quartz (FMQ) buffer at 1 kbar for the silica-undersaturated melt, and temperatures of 860 to 570 °C and an oxygen fugacity of 1.5 to 3.8 log units below FMQ for the oversaturated syenitic melt. The undersaturated melt evolved towards a more peralkaline composition. Crystallization of arfvedsonite plus aegirine

  5. Alkaline earth complexes of silylated aminopyridinato ligands: homoleptic compounds and heterobimetallic coordination polymers.

    PubMed

    Ortu, Fabrizio; Moxey, Graeme J; Blake, Alexander J; Lewis, William; Kays, Deborah L

    2013-11-04

    The synthesis and characterization of magnesium and calcium complexes of sterically demanding aminopyridinato ligands is reported. The reaction of the 2-Me3SiNH-6-MeC5H3N (L(1)H), 2-MePh2SiNH-6-MeC5H3N (L(2)H), and 2-Me3SiNH-6-PhC5H3N (L(3)H) with KH in tetrahydrofuran (THF) yielded potassium salts L(1)K(thf)0.5 (1), L(2)K (2), and L(3)K(thf)0.5 (3), which, through subsequent reaction with MgI2 and CaI2, afforded the homoleptic complexes (L)2Ae(thf)n [L = L(1), Ae = Mg, n = 1 (4); L = L(2), Ae = Mg, n = 0 (5); L = L(3), Ae = Mg, n = 0 (6); L = L(2), Ae = Ca, n = 2 (7)] and heterobimetallic calciates {[(L)3Ca]K}∞ [L = L(1) (8); L = L(2) (9)]. The solid state structure of 8 reveals a polymeric arrangement in which the calciate units are interlocked by bridging potassium ions. Metalation reactions between L(1)H or L(2)H and ((n)Bu)2Mg lead to the solvent-free compounds (L)2Mg [L = L(1) (10); L = L(2) (5)]. The bridged butyl mixed-metal complex [(L(1))Li(μ2-(n)Bu)Mg(L(1))]∞ (11) was also obtained via a cocomplexation reaction with (n)BuLi and ((n)Bu)2Mg. 11, which adopts a monodimensional polymeric array in the solid state, is a rare example of an alkyl-bridged Li/Mg complex and the first complex to feature an unsupported bridging butyl interaction between two metals. Changing the cocomplexation reaction conditions, the order of reagents added to the reactions mixture, and with the use of a coordinating solvent (tetrahydrofuran) formed the magnesiate complex (L(1))3MgLi(thf) (12).

  6. Magma storage of an alkali ultramafic igneous suite from Chamberlindalen, SW Svalbard

    NASA Astrophysics Data System (ADS)

    Gołuchowska, Karolina; Barker, Abigail K.; Czerny, Jerzy; Majka, Jarosław; Manecki, Maciej; Farajewicz, Milena; Dwornik, Maciej

    2016-10-01

    An alkali mafic-ultramafic igneous suite of composite intrusions, lenses and associated greenstones are hosted by Neoproterozoic metasedimentary sequences in Chamberlindalen, Southwest Svalbard. This study focuses on the alkali igneous suite of Chamberlindalen with a view to determining the conditions of magma storage. The rocks from Chamberlindalen display cumulate textures, are highly magnesian and are classified as alkaline by the occurrence of kaersutite. They have textures that indicate cocrystallization of primary magmatic minerals such as diopside, kaersutite-ferrokaersutite and biotite-phlogopite in different proportions. The historic magma plumbing system for the alkaline cumulates has been reconstructed by thermobarometry. Diopside and kaersutite crystallization in the alkaline cumulates show a dominant level of magma storage between 30 and 50 km in the subcontinental lithospheric mantle.

  7. The evolution of hyperagpaitic magma in the Ilímaussaq alkaline complex, Greenland: Fractional crystallization or intraplutonic assimilation ?

    NASA Astrophysics Data System (ADS)

    Andersen, Tom

    2013-04-01

    Hyperagpaitic rocks are highly peralkaline nepheline syenites in which minerals like ussingite (Na2AlSi3O8(OH)) and naujakasite (Na6FeAl4Si8O26) crystallize instead of or in addition to feldspars and feldspathoids, eudialyte is replaced by complex sodium-calcium silicate and phosphosilicate minerals like steenstrupine, and highly water soluble minerals such as villiaumite (NaF) form part of magmatic mineral assemblages. Most hyperagpaitic rocks are pegmatites or veins that can be attributed to late magmatic fluid-rock interaction (Khomyakov 1995). However, in the Ilímaussaq alkaline complex in South Greenland, hyperagpaitic villiaumite-, steenstrupine-, and naujakasite-bearing lujavrite (i.e. melanocratic, silica-undersaturated syenite) forms genuine magmatic intrusions (Sørensen and Larsen 2001, Rose-Hansen and Sørensen 2002). The agpaitic part of the Ilímaussaq complex consists of an upper series of sodalite foyaite and naujaite (i.e. sodalite-rich nepheline syenite) roof cumulates, and a floor series of kakortokite (i.e. modally layered arfvedsonite, eudialyte and nepheline + alkali feldspar cumulates). Different varieties of aegirine and arfvedsonite-bearing lujavrite make up a sandwich-horizon, and form intrusions in roof cumulate and non-agpaitic border group rocks (Ferguson 1964). The albite-nepheline-aegirine plane forms a critical boundary between agpaitic and potentially hyperagpaitic liquid compositions in the NaO0.5-AlO1.5-SiO2-FeOt tetrahedron (Andersen and Sørensen 2005). Both eudialyte and sodalite plot to the high-alkali side of this plane. In contrast, kakortokite and related rocks in Ilímaussaq plot within the less alkaline albite-nepheline-arfvedsonite-aegirine volume. Co-precipitation of sodalite and / or eudialyte with albite, nepheline and arfvedsonite from such magma will therefore prevent formation of more highly peralkaline (i.e. hyperagpaitic) residual liquids by closed system fractional crystallization. Hyperagpaitic residual

  8. Log evaluation of oil-bearing igneous rocks

    SciTech Connect

    Khatchikian, A.

    1983-12-01

    The evaluation of porosity, water saturation and clay content of oilbearing igneous rocks with well logs is difficult due to the mineralogical complexity of this type of rocks. The log responses to rhyolite and rhyolite tuff; andesite, dacite and zeolite tuff; diabase and basalt have been studied from examples in western Argentina and compared with values observed in other countries. Several field examples show how these log responses can be used in a complex lithology program to make a complete evaluation.

  9. Microscopic tubes in igneous rocks

    NASA Technical Reports Server (NTRS)

    Richter, D.; Simmons, G.

    1977-01-01

    Microscopic tubes have been observed in several igneous rocks and may be quite common. They occur in single crystals and have either elliptical or circular cross-sections 1 to 5 microns in diameter and are ten to hundreds of microns long. Microtubes may be hollow or partially or completely filled with another phase, but are distinct from acicular crystals of accessory minerals such as rutile. Microtubes can form by at least three processes: (1) the partial annealing of microcracks, (2) the natural etching of dislocations, or (3) the primary inclusion of fluid material during crystal growth.

  10. Mineral Detector for Igneous Rocks

    NASA Astrophysics Data System (ADS)

    Ishikawa, S. T.; Hart, S. D.; Gulick, V. C.

    2010-12-01

    We present a Raman spectral analysis tool that uses machine learning algorithms to classify pure minerals in igneous rocks. Experiments show greater than 90% accuracy classifying a test set of pure minerals against a database of similar reference minerals using an artificial neural network. Efforts are currently underway to improve this tool for use as a mineral detector in rock samples, an important milestone toward autonomously classifying rocks based on spectral, and previous imaging work. Although pure mineral classification has been widely successful, applying the same methods to rocks is difficult because the spectra may represent a combination of multiple, and often competing, mineral signatures. In such cases some minerals may appear with more intensity than others resulting in masking of weaker minerals. Furthermore, with our particular spectrometer (852 nm excitation, ~50 micron spot size), minerals such as potassium feldspar fluoresce, both obscuring its characteristic Raman features and suppressing those of weaker minerals. For example, plagioclase and quartz, two key minerals for determining the composition of igneous rocks, are often hidden by minerals such as potassium feldspar and pyroxene, and are consequently underrepresented in the spectral analysis. These technicalities tend to skew the perceived composition of a rock from its actual composition. Despite these obstacles, an experiment involving a training set of 26 minerals (plagioclase, potassium feldspar, pyroxene, olivine, quartz) and a test set of 57 igneous rocks (basalt, gabbro, andesite, diorite, dacite, granodiorite, rhyolite, granite) shows that generalizations derived from their spectral data are consistent with expected trends: as rock composition goes from felsic to mafic there is a marked increase in the detection of minerals such as plagioclase and pyroxene along with a decrease in the detection of minerals such as quartz and potassium feldspar. The results suggest that phaneritic

  11. Polychronous (Early Cretaceous to Palaeogene) emplacement of the Mundwara alkaline complex, Rajasthan, India: 40Ar/39Ar geochronology, petrochemistry and geodynamics

    NASA Astrophysics Data System (ADS)

    Pande, Kanchan; Cucciniello, Ciro; Sheth, Hetu; Vijayan, Anjali; Sharma, Kamal Kant; Purohit, Ritesh; Jagadeesan, K. C.; Shinde, Sapna

    2016-07-01

    The Mundwara alkaline plutonic complex (Rajasthan, north-western India) is considered a part of the Late Cretaceous-Palaeogene Deccan Traps flood basalt province, based on geochronological data (mainly 40Ar/39Ar, on whole rocks, biotite and hornblende). We have studied the petrology and mineral chemistry of some Mundwara mafic rocks containing mica and amphibole. Geothermobarometry indicates emplacement of the complex at middle to upper crustal levels. We have obtained new 40Ar/39Ar ages of 80-84 Ma on biotite separates from mafic rocks and 102-110 Ma on whole-rock nepheline syenites. There is no evidence for excess 40Ar. The combined results show that some of the constituent intrusions of the Mundwara complex are of Deccan age, but others are older and unrelated to the Deccan Traps. The Mundwara alkaline complex is thus polychronous and similar to many alkaline complexes around the world that show recurrent magmatism, sometimes over hundreds of millions of years. The primary biotite and amphibole in Mundwara mafic rocks indicate hydrous parental magmas, derived from hydrated mantle peridotite at relatively low temperatures, thus ruling out a mantle plume. This hydration and metasomatism of the Rajasthan lithospheric mantle may have occurred during Jurassic subduction under Gondwanaland, or Precambrian subduction events. Low-degree decompression melting of this old, enriched lithospheric mantle, due to periodic diffuse lithospheric extension, gradually built the Mundwara complex from the Early Cretaceous to Palaeogene time.

  12. Volume characteristics and element transfer of fenite aureoles: a case study from the Iivaara alkaline complex, Finland

    NASA Astrophysics Data System (ADS)

    Sindern, Sven; Kramm, Ulrich

    2000-03-01

    Fenitization in granodioritic rocks has been investigated taking the Iivaara alkaline complex (Finland) as a case study. Five main fenitization reactions responsible for the transition from a granodioritic precursor mineral assemblage to a syenitic or even cancrinite-syenitic mineral assemblage of the fenites are set up. An assessment of element transfer and volume change associated with each of these reactions indicates a general volume loss of about 20% due to fenitization. High activities of Na, Ca, Mg and Fe as well as a low H 2O/CO 2 ratio in the fenitizing fluid phase are indicated. Si, which is the main component released from the precursor rock, was redistributed within the aureole and formed pyroxene dominated mineral assemblages in a reaction with the fenitizing fluid. These vein-type pyroxenites can be found cross-cutting all fenite types. Compositional data of aegirine augite in the fenites reveal disequilibria and feldspar compositions point to minimum temperatures for the production of fenites with syenitic compositions of 660°C and also indicate fast cooling. A Sr isotope characterization of the fenites allows assessment of minimum fluid-rock weight-ratios in the fenite aureole of 0.023-2.3. The element transfer scheme developed in this study is applicable to other localities since many aureoles formed in granitic to granodioritic host rocks have petrographic characteristics similar to the Iivaara fenites.

  13. Mind Over Magma: The Story of Igneous Petrology

    NASA Astrophysics Data System (ADS)

    Snyder, Don

    2004-01-01

    In the centuries that enquiring minds have studied and theorized about igneous rocks, much progress has been made, both in accumulating observations and in developing theories. Yet, writing a history of this progress is a daunting undertaking. The volume of the literature is vast and in multiple languages; the various lines of inquiry are diverse and complex; and the nomenclature is sometimes abstruse. On top of these challenges, many of its principal issues have yet to find a definitive consensus. With the exception of a few topical studies, historians of science have virtually avoided the subject. In Mind Over Magma: The Story of Igneous Petrology, Davis Young has taken on the challenge of writing a comprehensive survey of the study of igneous rocks, and the result has been a remarkable book of meticulous scholarship. Igneous petrology is a vast subject, and it is not obvious how best to organize its history. Young takes a topical approach, generally grouping together various studies by either the problem being investigated or the method of attack. These topics span the earliest times to the present, with an emphasis on recurring themes, such as the causes of magmatic diversity and the origins of the granitic rocks. The range of topics includes most of the subjects central to the field over its history. As much as is practical, topics are discussed in chronological order, and along the way, the reader is treated to biographical sketches of many of the key contributors. This organization proves effective in dealing with the multitude of concepts.

  14. Synchronous alkaline and subalkaline magmatism during the late Neoproterozoic-early Paleozoic Ross orogeny, Antarctica: Insights into magmatic sources and processes within a continental arc

    NASA Astrophysics Data System (ADS)

    Hagen-Peter, Graham; Cottle, John M.

    2016-10-01

    Extensive exposure of intrusive igneous rocks along the Ross orogen of Antarctica-an ancient accretionary orogen on the margin of East Gondwana-provides an exceptional opportunity to study continental arc magmatism. There is significant petrologic and geochemical variability in igneous rocks within a 500-km-long segment of the arc in southern Victoria Land. The conspicuous occurrence of carbonatite and alkaline silicate rocks (nepheline syenite, A-type granite, and alkaline mafic rocks) adjacent to large complexes of subalkaline granitoids is not adequately explained by traditional models for continental arc magmatism. Extensive geochemical analysis (> 100 samples) and zircon U-Pb geochronology (n = 70) confirms that alkaline and carbonatitic magmatism was partially contemporaneous with the emplacement of large subduction-related igneous complexes in adjacent areas. Major pulses of subalkaline magmatism were compositionally distinct and occurred at different times along the arc. Large bodies of subalkaline orthogneiss and granite (sensu lato) were emplaced over similar time intervals (ca. 25 Myr) to the north (ca. 515-492 Ma) and south (ca. 550-525 Ma) of the alkaline magmatic province, although the initiation of these major pulses of magmatism was offset by ca. 35 Myr. Alkaline and carbonatitic magmatism spanned at least ca. 550-509 Ma, overlapping with voluminous subalkaline magmatism in adjacent areas. The most primitive rocks from each area have similarly enriched trace element compositions, indicating some common characteristics of the magma sources along the arc. The samples from the older subalkaline complex have invariably low Sr/Y ratios (< 40), consistent with relatively shallow magma generation and differentiation. The younger subalkaline complex and subalkaline rocks within the area of the alkaline province extend to higher Sr/Y ratios (up to 300), indicative of generation and differentiation at deeper levels. The significant spatial and temporal

  15. Teaching Igneous Geology in Physical Geography: Some Recommendations.

    ERIC Educational Resources Information Center

    Powell, William E.

    1982-01-01

    The most common igneous minerals and their diagnostic properties, which the author considers the most significant and pragmatic aspect of igneous geology for physical geography students, are discussed. The nature of igneous geology is also examined. (RM)

  16. Kinetics of crystallization of igneous rocks

    SciTech Connect

    Kirkpatrick, R.J.

    1981-01-01

    The geochemistry of igneous rocks is discussed, with the primary objectives of bringing together the theories underlying the kinetics of crystallization of igneous rocks and illustrating the use of these theories in understanding experimental and observational data. The primary purpose of the chapter is to introduce current thinking about the kinetics of igneous rocks and to provide a basis for understanding other work. A basic assumption made in the discussion is that the rate of any chemical reaction, including the crystallization of igneous rocks, is zero at equilibrium and proceeds at a finite rate only at a finite deviation from equilibrium. As such, an understanding of the processes operating in igneous rocks requires an understanding of how deviation from equilibrium affects the rates and mechanisms of the processes occurring during crystallization. These processes are detailed, with special emphasis given to nucleation and crystal growth. (JMT)

  17. Ureilites are not igneous differentiates

    NASA Technical Reports Server (NTRS)

    Clayton, Robert N.; Mayeda, Toshiko K.

    1988-01-01

    Although most all meteorites are as old as the solar system (4.5 billion years), they can be subdivided into primitive and evolved groups, depending on the extent of their chemical and physical processing. Primitive meteorites, most of which are chondrites, are assemblages of dust and millimeter-sized pellets from the presolar nebula, which were not extensively heated and processed since their assembly. Thus they provide information about the conditions in the nebular cloud. Many of the evolved meteorites are achondrites, which are igneous rocks produced by melting on or within an asteroidal object known as the parent body. A major unsolved problem in solar system studies is identification of the source of heat which led to melting of the achondrites. The role of oxygen isotopes in establishing genetic relationships among meteorites is examined.

  18. Alkaline side-coordination strategy for the design of nickel(II) and nickel(III) bis(1,2-diselenolene) complex based materials.

    PubMed

    Ribas, Xavi; Dias, João C; Morgado, Jorge; Wurst, Klaus; Santos, Isabel C; Almeida, Manuel; Vidal-Gancedo, José; Veciana, Jaume; Rovira, Concepció

    2004-06-14

    The deprotonated form of the pyrazine-2,3-diselenol (pds) ligand, pds(2-), reacts with Ni(II) inorganic salts to form the nickel compounds [Ni(II)(pds)(2)](nBu(4)N)(2) (1), [Ni(II)(pds)(2)]Na(2).2H(2)O (2), and [Ni(III)(pds)(2)](2)Na(2).4H(2)O (3), depending on the reaction conditions. They are characterized by NMR, EPR, UV-vis, and IR spectroscopies, elemental analysis, cyclic voltammetry, and X-ray crystallography. The crystal structure of compound 3 shows the formation of segregated stacks of Ni(pds)(2-) units, with a strong dimerization along the stacks. The stacked fashion of the crystal packing was expected since the supramolecular forces of the alkaline side coordination to the pyrazine moieties dominate, as happens in the recently reported analogous copper system [Cu(III)(pds)(2)]Na.2H(2)O. The structure of 2 further emphasizes the alkaline coordination as the dominating supramolecular event, and an orthogonal array of 2D layers is observed. The absence of alkaline cations in complex 1 is reflected in a crystal packing with isolated complex Ni(pds)(2)(2-) units. The dimerization found in the paramagnetic Ni(III) complex 3 promotes a very strong antiferromagnetic interaction, leading to a singlet ground state.

  19. Geochemical and modal data for igneous rocks associated with epithermal mineral deposits

    USGS Publications Warehouse

    du Bray, Edward A.

    2014-01-01

    The purposes of this report are to (1) present available geochemical and modal data for igneous rocks associated with epithermal mineral deposits and (2) to make those data widely and readily available for subsequent, more in-depth consideration and interpretation. Epithermal precious and base-metal deposits are commonly associated with subduction-related calc-alkaline to alkaline arc magmatism as well as back-arc continental rift magmatism. These deposits form in association with compositionally diverse extrusive and intrusive igneous rocks. Temperature and depth regimes prevailing during deposit formation are highly variable. The deposits form from hydrothermal fluids that range from acidic to near-neutral pH, and they occur in a variety of structural settings. The disparate temperature, pressure, fluid chemistry, and structural controls have resulted in deposits with wide ranging characteristics. Economic geologists have employed these characteristics to develop classification schemes for epithermal deposits and to constrain the important genetic processes responsible for their formation.

  20. Charge-separated and molecular heterobimetallic rare earth-rare earth and alkaline earth-rare earth aryloxo complexes featuring intramolecular metal-pi-arene interactions.

    PubMed

    Deacon, Glen B; Junk, Peter C; Moxey, Graeme J; Ruhlandt-Senge, Karin; St Prix, Courtney; Zuniga, Maria F

    2009-01-01

    Treatment of a rare earth metal (Ln) and a potential divalent rare earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200-250 degrees C) afforded heterobimetallic aryloxo complexes, which were structurally characterised. A charge-separated species [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] was obtained for a range of metals, demonstrating the similarities between the chemistry of the divalent rare earth metals and the alkaline earth metals. The [(Ln'/Ae)(2)(Odpp)(3)](+) cation in the heterobimetallic structures is unusual in that it consists solely of bridging aryloxide ligands. A molecular heterobimetallic species [AeEu(Odpp)(4)] (Ae = Ca, Sr, Ba) was obtained by treating an alkaline earth metal and Eu metal with HOdpp at elevated temperatures. Similarly, [BaSr(Odpp)(4)] was prepared by treating Ba metal and Sr metal with HOdpp. Treatment of [Ba(2)(Odpp)(4)] with [Mg(Odpp)(2)(thf)(2)] in toluene afforded [Ba(2)(Odpp)(3)][Mg(Odpp)(3)(thf)]. Analogous solution-based syntheses were not possible for [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] complexes, for which the free-metal route was essential. As a result of the absence of additional donor ligands, the crystal structures of the heterobimetallic complexes feature extensive pi-Ph-metal interactions involving the pendant phenyl groups of the Odpp ligands, thus enabling the large electropositive metal atoms to attain coordination saturation. The charge-separated heterobimetallic species were purified by extraction with toluene/thf mixtures at ambient temperature (Ba-containing compounds) or by extraction with toluene under pressure above the boiling point of the solvent (other products). In donor solvents, heterobimetallic complexes other than those containing barium were found to fragment into homometallic species.

  1. Identifying the presence of a disulfide linkage in peptides by the selective elimination of hydrogen disulfide from collisionally activated alkali and alkaline earth metal complexes.

    PubMed

    Kim, Hugh I; Beauchamp, J L

    2008-01-30

    We report a new method for identifying disulfide linkages in peptides using mass spectrometry. This is accomplished by collisional activation of singly charged cationic alkali and alkaline earth metal complexes, which results in the highly selective elimination of hydrogen disulfide (H2S2). Complexes of peptides possessing disulfide bonds with sodium and alkaline earth metal are generated using electrospray ionization (ESI). Isolation followed by collision induced dissociation (CID) of singly charged peptide complexes results in selective elimination of H2S2 to leave newly formed dehydroalanine residues in the peptide. Further activation of the product yields sequence information in the region previously short circuited by the disulfide bond. For example, singly charged magnesium and calcium ion bound complexes of [Lys8]-vasopressin exhibit selective elimination of H2S2 via low-energy CID. Further isolation of the product followed by CID yields major b- and z-type fragments revealing the peptide sequence in the region between the newly formed dehydroalanine residues. Numerous model peptides provide mechanistic details for the selective elimination of H2S2. The process is initiated starting with a metal stabilized enolate anion at Cys, followed by cleavage of the S-C bond. An examination of the peptic digest of insulin provides an example of the application of the selective elimination of H2S2 for the identification of peptides with disulfide linkages. The energetics and mechanisms of H2S2 elimination from model compounds are investigated using density functional theory (DFT) calculations.

  2. Structure reactivity and thermodynamic analysis on the oxidation of ampicillin drug by copper(III) complex in aqueous alkaline medium (stopped-flow technique)

    NASA Astrophysics Data System (ADS)

    Shetti, Nagaraj P.; Hegde, Rajesh N.; Nandibewoor, Sharanappa T.

    2009-07-01

    Oxidation of penicillin derivative, ampicillin (AMP) by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of 0.01-mol dm -3 was studied spectrophotometrically. The reaction between DPC and ampicillin in alkaline medium exhibits 1:4 stoichiometry (ampicillin:DPC). Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidences, a mechanism involving the protonated form of DPC as the reactive oxidant species has been proposed. The oxidation reaction in alkaline medium has been shown to proceed via a DPC-AMP complex, which decomposes slowly in a rate determining step to yield phenyl glycine (PG) and free radical species of 6-aminopenicillanic acid (6-APA), followed by other fast steps to give the products. The two major products were characterized by IR, NMR, LC-MS and Spot test. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed and thermodynamic quantities were also determined.

  3. Inherited igneous zircons in jadeitite predate high-pressure metamorphism and jadeitite formation in the Jagua Clara serpentinite mélange of the Rio San Juan Complex (Dominican Republic)

    NASA Astrophysics Data System (ADS)

    Hertwig, Andreas; McClelland, William C.; Kitajima, Kouki; Schertl, Hans-Peter; Maresch, Walter V.; Stanek, Klaus; Valley, John W.; Sergeev, Sergey A.

    2016-05-01

    This study utilizes zircon SIMS U-Pb dating, REE and trace-element analysis as well as oxygen isotope ratios of zircon to distinguish jadeite-rich rocks that formed by direct crystallization from a hydrous fluid from those that represent products of a metasomatic replacement process. Zircon was separated from a concordant jadeitite layer and its blueschist host, as well as from loose blocks of albite-jadeite rock and jadeitite that were all collected from the Jagua Clara serpentinite-matrix mélange in the northern Dominican Republic. In the concordant jadeitite layer, three groups of zircon domains were distinguished based on both age as well as geochemical and oxygen isotope values: age groups old (117.1 ± 0.9 Ma), intermediate (three dates: 90.6, 97.3, 106.0 Ma) and young (77.6 ± 1.3 Ma). Zircon populations from the blueschist host as well as the other three jadeite-rich samples generally match zircon domains of the old age group in age as well as geochemistry and oxygen isotope ratios. Moreover, these older zircon populations are indistinguishable from zircon typical of igneous oceanic crust and hence are probably inherited from igneous protoliths of the jadeite-rich rocks. Therefore, the results suggest that all investigated jadeite-rich rocks were formed by a metasomatic replacement process. The younger domains might signal actual ages of jadeitite formation, but there is no unequivocal proof for coeval zircon-jadeite growth.

  4. Copper(II) complexes with cyanoguanidine and o-phenanthroline: Theoretical studies, in vitro antimicrobial activity and alkaline phosphatase inhibitory effect

    NASA Astrophysics Data System (ADS)

    Martínez Medina, Juan J.; Islas, María S.; López Tévez, Libertad L.; Ferrer, Evelina G.; Okulik, Nora B.; Williams, Patricia A. M.

    2014-01-01

    Calculations based on density functional methods are carried out for two Cu(II) complexes with cyanoguanidine (cnge) and o-phenanthroline (o-phen): [Cu(o-phen)2(cnge)](NO3)2ṡ2H2O (1) and [Cu(o-phen)(cnge)(H2O)(NO3)2] (2). The calculated geometrical parameters are in agreement with the experimental values. The results of Atoms in Molecules (AIM) topological analysis of the electron density indicate that the Cu-N(phen) bonds in complex (1) have lower electron density, suggesting that those bonds are stronger in complex (2). Moreover, the ionic character of the Cu-N bond in the complex (1) is slightly stronger than that in the complex (2) and this situation would explain the fact that only complex (2) was stable in water solution. For this reason, the antimicrobial and enzymatic assays were performed using complex (2). It is well known that the increased use of antibiotics has resulted in the development of resistant bacterial and fungal strains. In this context, the study of novel antimicrobial agents has an enormous importance and metal complexes represent an interesting alternative for the treatment of infectious diseases. The aim of this work is to prove the modification of some biological properties like antimicrobial activity or alkaline phosphatase inhibitory activity upon copper complexation.

  5. Geochemistry and petrogenesis of late Ediacaran (605-580 Ma) post-collisional alkaline rocks from the Katherina ring complex, south Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Azer, M. K.; Obeid, M. A.; Ren, M.

    2014-10-01

    The Katherina ring complex (KRC) in the central part of south Sinai, Egypt, is a typical ring complex of late Neoproterozoic age (605-580 Ma). It was developed during the final tectono-magmatic stage of the north Arabian-Nubian Shield (ANS) during evolution of the Pan-African crust. The KRC includes Katherina volcanics, subvolcanic bodies, ring dykes and Katherina granitic pluton. The Katherina volcanics represent the earliest stage of the KRC, which was subsequently followed by emplacement of the subvolcanic bodies and ring dykes. The Katherina granitic pluton depicts as the latest evolution stage of the KRC that intruded all the early formed rock units in the concerned area. The Katherina volcanics are essentially composed of rhyolites, ignimbrite, volcanic breccia and tuffs. Mineralogically, the peralkaline rhyolites contain sodic amphiboles and aegirine. The rhyolite whole rock chemistry has acmite-normative character. The subvolcanic bodies of the KRC are represented by peralkaline microgranite and porphyritic quartz syenite. The ring dykes are semicircular in shape and consist mainly of quartz syenite, quartz trachyte and trachybasalt rock types. The Katherina subvolcanic rocks, volcanic rocks as well as the ring dykes are alkaline or/and peralkaline in nature. The alkaline granitic pluton forms the inner core of the KRC, including the high mountainous areas of G. Abbas Pasha, G. Bab, G. Katherina and G. Musa. These mountains are made up of alkaline syenogranite and alkali feldspar granite. The mantle signature recorded in the KRC indicates a juvenile ANS crust partial melting process for the generation of this system. The evolution of the KRC rocks is mainly dominated by crystal fractionation and crustal contamination. Mineral geothermometry points to the high temperature character of the KRC, up to 700-1100 °C.

  6. Variations in magmatic processes among igneous asteroids

    NASA Technical Reports Server (NTRS)

    Gaffey, M. J.

    1991-01-01

    Six asteroid classes (types V, E, A, R, M, S) are composed primarily of differentiated assemblages produced by igneous processes within their parent planetesimals. These are identified by surface materials which deviate from a chondritic composition to a degree that require igneous chemical fractionation processes. There are large variations among these igneous asteroids in the peak temperatures attained, in the efficiency of magmatic phase separation, and in the depth within the original parent body exposed at the present surface. These variations provide important constraints on the nature of asteroidal heating events, on the differentiation processes within small planetary bodies, and on the disruption of those parent bodies. Variations due to depth within the parent body and due to degree of magmatic differentiation are detailed.

  7. Organic protomolecule assembly in igneous minerals.

    PubMed

    Freund, F; Staple, A; Scoville, J

    2001-02-27

    CH stretching bands, nu(CH), in the infrared spectrum of single crystals of nominally high purity, of laboratory-grown MgO, and of natural upper mantle olivine, provide an "organic" signature that closely resembles the symmetrical and asymmetrical C--H stretching modes of aliphatic -CH(2) units. The nu(CH) bands indicate that H(2)O and CO(2), dissolved in the matrix of these minerals, converted to form H(2) and chemically reduced C, which in turn formed C--H entities, probably through segregation into defects such as dislocations. Heating causes the C--H bonds to pyrolyze and the nu(CH) bands to disappear, but annealing at 70 degrees C causes them to reappear within a few days or weeks. Modeling dislocations in MgO suggests that the segregation of C can lead to C(x) chains, x = 4, with the terminal C atoms anchored to the MgO matrix by bonding to two O(-). Allowing H(2) to react with such C(x) chains leads to [O(2)C(CH(2))(2)CO(2)] or similar precipitates. It is suggested that such C(x)--H(y)--O(z) entities represent protomolecules from which derive the short-chain carboxylic and dicarboxylic and the medium-chain fatty acids that have been solvent-extracted from crushed MgO and olivine single crystals, respectively. Thus, it appears that the hard, dense matrix of igneous minerals represents a medium in which protomolecular units can be assembled. During weathering of rocks, the protomolecular units turn into complex organic molecules. These processes may have provided stereochemically constrained organics to the early Earth that were crucial to the emergence of life.

  8. Organic protomolecule assembly in igneous minerals

    PubMed Central

    Freund, Friedemann; Staple, Aaron; Scoville, John

    2001-01-01

    C—H stretching bands, νCH, in the infrared spectrum of single crystals of nominally high purity, of laboratory-grown MgO, and of natural upper mantle olivine, provide an “organic” signature that closely resembles the symmetrical and asymmetrical C—H stretching modes of aliphatic —CH2 units. The νCH bands indicate that H2O and CO2, dissolved in the matrix of these minerals, converted to form H2 and chemically reduced C, which in turn formed C—H entities, probably through segregation into defects such as dislocations. Heating causes the C—H bonds to pyrolyze and the νCH bands to disappear, but annealing at 70°C causes them to reappear within a few days or weeks. Modeling dislocations in MgO suggests that the segregation of C can lead to Cx chains, x = 4, with the terminal C atoms anchored to the MgO matrix by bonding to two O−. Allowing H2 to react with such Cx chains leads to [O2C(CH2)2CO2] or similar precipitates. It is suggested that such Cx—Hy—Oz entities represent protomolecules from which derive the short-chain carboxylic and dicarboxylic and the medium-chain fatty acids that have been solvent-extracted from crushed MgO and olivine single crystals, respectively. Thus, it appears that the hard, dense matrix of igneous minerals represents a medium in which protomolecular units can be assembled. During weathering of rocks, the protomolecular units turn into complex organic molecules. These processes may have provided stereochemically constrained organics to the early Earth that were crucial to the emergence of life. PMID:11226206

  9. Organic Protomolecule Assembly in Igneous Minerals

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann; Staple, Aaron; Scoville, John

    2001-01-01

    C-H stretching bands in the infrared spectrum of single crystals of nominally high purity, laboratory-grown MgO and of natural upper mantle olivine provide an "organic" signature that closely resembles the symmetrical and asymmetrical C-H stretching modes of aliphatic -CH2- units. The C-H stretching bands indicate that H20 and CO2, dissolved in the matrix of these minerals, converted to form H2 and chemically reduced C, which in turn formed C-H entities, probably through segregation into defects such as dislocations. Heating causes the C-H bonds to pyrolyze and the C-H stretching bands to disappear, but annealing at 70 C causes them to reappear within a few days or weeks. Modeling dislocations in MgO suggests that the segregation of C can lead to Cx chains, x less than or equal to 4, with the terminal C atoms anchored to the MgO matrix by bonding to two U. Allowing H2 to react with such Cx chains leads to [O2C(CH2)2CO2] or similar precipitates. It is suggested that such Cx-Hy-Oz entities represent protomolecules from which derive the short-chain carboxylic and dicarboxylic and of the medium-chain fatty acids that have been solvent-extracted from crushed MgO and olivine single crystals, respectively. Thus it appears that the hard, dense matrix of igneous minerals represents a medium in which protomolecular units can be assembled. During weathering of rocks the protomolecular units turn into complex organic molecules. These processes may have provided stereochemically constrained organics to the early Earth that were crucial to the emergence of Life.

  10. Zr and REE mineralization in sodic lujavrite from the Saima alkaline complex, northeastern China: A mineralogical study and comparison with potassic rocks

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Wang, Ru-Cheng; Yang, Jin-Hui; Wu, Fu-Yuan; Zhang, Wen-Lan; Gu, Xiang-Ping; Zhang, Ai-Cheng

    2016-10-01

    The Triassic Saima alkaline complex on the Liaodong Peninsula, northeastern China, consists mainly of potassic phonolite, nepheline syenite, and sodic lujavrite. The lujavrite shows significant Zr-REE mineralization, which is present in the form of early magmatic, Zr-REE-enriched clinopyroxene (30%-40%), titanite (5%), and loparite-(Ce), and late magmatic to hydrothermal wadeite, widespread eudialyte group minerals (5%-10%), and catapleiite. Ultimately, the fractionation of the alkaline magma leads to the crystallization of mosandrite and hezuolinite. Textural relations and compositional variation among the characteristic Zr-REE-bearing minerals record that both Zr and REEs were strongly incompatible in the sodic melt, but that Zr mineralization preceded REE mineralization. The main Zr-REE mineralization in the Saima lujavrite resulted from the high peralkalinity, Na/K ratio and HFSE content, low oxygen fugacity, and the intensive activity of water and volatiles of its evolving magma. The discontinuous and abrupt changes in melt composition and mineral assemblage from the potassic nepheline syenite of the complex to the sodic lujavrite suggest that their magma was derived from different episodes of magmatic activity with different physico-chemical characteristics, rather than from the continuous evolution of a single magmatic event.

  11. Theoretical petrology. [of igneous and metamorphic rocks

    NASA Technical Reports Server (NTRS)

    Stolper, E.

    1979-01-01

    In the present paper, some areas of growing interest in the American efforts in petrology during the 1975-1978 quadrennium are reviewed. In igneous petrology, studies of structures and thermodynamic properties of silicate melts and of kinetics of igneous processes are in a period of rapid growth. Plate tectonic concepts have had (and will no doubt continue to have) an important influence by focusing interest on specific problems and by providing a framework for the understanding of petrogenesis. An understanding of mantle processes and evolution through the integration of petrological, geophysical, and geochemical constraints has been developed over the past 20 years, and will undoubtedly provide direction for future petrological studies.

  12. The coordination complex structures and hydrogen bonding in the three-dimensional alkaline earth metal salts (Mg, Ca, Sr and Ba) of (4-aminophenyl)arsonic acid.

    PubMed

    Smith, Graham; Wermuth, Urs D

    2017-01-01

    (4-Aminophenyl)arsonic acid (p-arsanilic acid) is used as an antihelminth in veterinary applications and was earlier used in the monosodium salt dihydrate form as the antisyphilitic drug atoxyl. Examples of complexes with this acid are rare. The structures of the alkaline earth metal (Mg, Ca, Sr and Ba) complexes with (4-aminophenyl)arsonic acid (p-arsanilic acid) have been determined, viz. hexaaquamagnesium bis[hydrogen (4-aminophenyl)arsonate] tetrahydrate, [Mg(H2O)6](C6H7AsNO3)·4H2O, (I), catena-poly[[[diaquacalcium]-bis[μ2-hydrogen (4-aminophenyl)arsonato-κ(2)O:O']-[diaquacalcium]-bis[μ2-hydrogen (4-aminophenyl)arsonato-κ(2)O:O

  13. Geochemical Behavior of Selenium in Igneous Systems

    NASA Astrophysics Data System (ADS)

    Jenner, F. E.; Mavrogenes, J. A.; Arculus, R. J.; O'Neill, H. S.

    2008-12-01

    Selenium (Se) is generally assumed to behave much like sulfur (S) in igneous systems. However, it is unclear how valid this assumption is considering that so little is known about the geochemical behaviour of Se. Constraining the range in Se and S concentrations of mantle-derived magmas is important to studies of: core segregation; the composition of late-accreted material; collisional erosion models; processes of mantle melting in various tectonic environments; and recycling of lithospheric components into the mantle, to mention only a few. Previous estimates of the S/Se of primitive and depleted mantle assume that S-Se are similar to Zr-Hf and Nb-Ta in their geochemical coherence, and that S/Se of the Earth's mantle is chondritic (Palme and O"Neill 2003 and references therein). Due to the low abundances of Se in mantle-derived rocks and the lack of calibration materials for routine analysis (i.e. NIST 612), this assumption remains unchallenged. Using a combination of SHRIMP, electron probe, and LA-ICP-MS techniques the concentration of Se in NIST 612 and BCR-2G was obtained to permit rapid in situ LA-ICP-MS analysis of Se concentrations in volcanic glasses. We have obtained Se, S, major and comprehensive trace element data for volcanic glasses from a global range of tectonic settings (mid-ocean ridges, ocean island, island arc and back-arc basins) to improve understanding of the behaviour of Se during igneous processes (e.g. partial melting, fractional crystallisation, and volatile phase separation). Analysis of a range of mid-ocean ridge glasses shows that Se behaves as an incompatible element, but is decoupled from S as the S/Se extends to values well in excess of the chondritic estimate (i.e. 2528; Palme and O"Neill 2003). During back-arc basin and island-arc magmatism, the abundance, systematics and S/Se are diverse. For example, at a specific MgO content, the absolute abundance of Se varies with depletion of the mantle source. Within back-arc suites derived

  14. Oligocene caldera complex and calc-alkaline tuffs and lavas of the Indian Peak volcanic field, Nevada and Utah

    USGS Publications Warehouse

    Best, M.G.; Christiansen, E.H.; Blank, H.R.

    1989-01-01

    The Indian Peak volcanic field is representative of the more than 50 000 km3 of ashflow tuff and tens of calderas in the Great Basin that formed during the Oligocene-early Miocene "ignimbrite flareup' in southwestern North America. These dominantly high-K calc-alkaline rocks are a record of the birth, maturation, and death of a large, open, continental magma system that was probably initiated and sustained by influx of mafic magma derived from a southward-migrating locus of magma production in the mantle. Recurrent production of very large batches (some greater than 3000 km3) of quite uniform dacite magmas appears to have required combination of andesite magma and crustal silicic material in vigorously convecting chambers. Compositional data indicate that rhyolites are polygenetic. As the main locus of mantle magma production shifted southward, trachydacite magma could have been produced by fractionation of andesitic magma within the crust. -from Author

  15. Magmatic systems of large continental igneous province

    NASA Astrophysics Data System (ADS)

    Sharkov, Evgenii

    2014-05-01

    Large igneous provinces (LIPs) of the modern type are known from the middle Paleoproterozoic and have a great abundance in the Phanerozoic. The most researches considered their appearance with ascending of the mantle thermochemical superplumes which provided simultaneously eruption of the same type of lavas on the huge territories. Judging on presence among them different subprovinces, formation of concrete magmatic systems were linked with protuberances (secondary plumes) on the superplumes surfaces. We suggest that origin of such plumes was linked with local enrichment of upper part of the superplumes head beneath roofing by fluid components; it led to lowering of the plume material density and initiated ascending of the secondary plumes. As a result, their heads, where partial melting occurred, can reach the level of the upper crust as it follows from absence of lower-crustal rocks among xenoliths in basalts, although mantle xenoliths existed in them. Important feature of LIPs is presence of two major types of mafic lavas: (1) geochemical-enriched alkali Fe-Ti basalts and picrites, and (2) basalts of normal alkalinity (tholeiites) with different contents of TiO2. At that the first type of mafites are usually typical for lower parts of LIPs which initially developed as continental rifts, whereas the second type composed the upper part of the traps' cover. Magmatic systems of the LIPs are subdivided on three levels of different deep: (1) zones of magma generation, (2) areas of transitional magma chambers where large often layered intrusive bodies are formed, and (3) areas on surface where lava eruptions and subvolcanic intrusions occurred. All these levels are linked by feeder dykes. The least known element of the system is area of magma generation, and, especially, composition of melting substratum. Important information about it is contained in aforementioned mantle xenoliths in alkali basalts and basanites. They practically everywhere are represented by two

  16. Electrocatalysis for dioxygen reduction by a μ-oxo decavanadium complex in alkaline medium and its application to a cathode catalyst in air batteries

    NASA Astrophysics Data System (ADS)

    Dewi, Eniya Listiani; Oyaizu, Kenichi; Nishide, Hiroyuki; Tsuchida, Eishun

    The redox behavior of a decavanadium complex [(VO) 10(μ 2-O) 9(μ 3-O) 3(C 5H 7O 2) 6] ( 1) was studied using cyclic voltammetry under acidic and basic conditions. The reduction potential of V(V) was found at less positive potentials for higher pH electrolyte solutions. The oxygen reduction at complex 1 immobilized on a modified electrode was examined using cyclic voltammetry and rotating ring-disk electrode techniques in the 1 M KOH solutions. On the basis of measurements using a rotating disk electrode (RDE), the complex 1 was found to be highly active for the direct four-electron reduction of dioxygen at -0.2 V versus saturated calomel electrode (SCE). The complex 1 as a reduction catalyst of O 2 with a high selectivity was demonstrated using rotating ring-disk voltammograms in alkaline solutions. The application of complex 1 as an oxygen reduction catalyst at the cathode of zinc-air cell was also examined. The zinc-air cell with the modified electrode showed a stable discharge potential at approximately 1 V with discharge capacity of 80 mAh g -1 which was about five times larger than that obtained with the commonly used manganese dioxide catalyst.

  17. Fluid inclusion studies on the Koraput Alkaline Complex, Eastern Ghats Province, India: Implications for mid-Neoproterozoic granulite facies metamorphism and exhumation

    NASA Astrophysics Data System (ADS)

    Nanda, J.; Panigrahi, M. K.; Gupta, S.

    2014-03-01

    Following ultrahigh temperature granulite metamorphism at ˜1 Ga, the Eastern Ghats Province of India was intruded by the Koraput Alkaline Complex, and was subsequently re-metamorphosed in the granulite facies in the mid-Neoproterozoic time. Fluid inclusion studies were conducted on silica undersaturated alkali gabbro and syenites in the complex, and a pre-metamorphic pegmatitic granite dyke that intrudes it. High density (1.02-1.05 g/cc), pseudo-secondary pure CO2 inclusions are restricted to metamorphic garnets within the gabbro and quartz within the granite, whereas moderate (˜0.92-0.95 g/cc) and low density (˜0.75 g/cc) secondary inclusions occur in garnet, magmatic clinopyroxene, plagioclase, hornblende and quartz. The isochores calculated for high density pseudo-secondary inclusions pass very close to the peak metamorphic window (˜8 kbar, 750 °C), and are interpreted to represent the fluid present during peak metamorphism that was entrapped by the growing garnet. Microscopic round inclusions of undigested, relict calcite in garnet suggest that the CO2 present during metamorphism of the complex was internally derived through carbonate breakdown. Pure to low salinity (0.00-10.1 wt% NaCl equivalent) aqueous intra-/intergranular inclusions showing unimodal normal distribution of final ice-melting temperature (Tm) and temperature of homogenization (Th) are present only in quartz within the granite. These represent re-equilibrated inclusions within the quartz host that were entrapped at the metamorphic peak. Rare, chemically precipitated graphite along the walls of carbonic inclusions is interpreted as a post-entrapment reaction product formed during decompression. The fluid inclusion evidence is consistent with rapid exhumation of a thickened lower crust following the mid-Neoproterozoic granulite facies metamorphic event. The study suggests that mantle CO2, transported by alkaline magma into the crust, was locked up within carbonates and released during

  18. Igneous and tectonic evolution of Venusian and terrestrial coronae

    NASA Technical Reports Server (NTRS)

    Kargel, J. S.; Komatsu, G.

    1992-01-01

    A great variety of tectonic and volcanic features have been documented on Venus. It is widely appreciated that there are close spatial associations among certain types of tectonic structures and some classes of volcanic flows and constructs. Coronae are endowed with a particularly rich variety of volcanism. It is thought that coupled tectonic and volcanic aspects of coronae are cogenetic manifestations of mantle plumes. An outstanding feature of most venusian coronae is their circular or elliptical shape defined by peripheral zones of fracturing and/or folding. Some coronae are composite, consisting of two or more small coronae within a larger enclosing corona, suggesting complex histories of structured diapirism analogous in some ways to salt dome tectonics. Coronae range widely in size, from smaller than 100 km to over 1000 km in diameter. Volcanic features associated with venusian coronae include lunar-like sinuous rilles, thin lava flows, cinder cone-like constructs, shield volcanos, and pancake domes. Several types of volcanic features are often situated within or near a single corona, in many instances including land-forms indicating effusions of both low- and high-viscosity lavas. In some cases stratigraphic evidence brackets emplacement of pancake domes during the period of tectonic development of the corona, thus supporting a close link between the igneous and tectonic histories of coronae. These associations suggest emplacement of huge diapirs and massive magmatic intrusions, thus producing the tectonic deformations defining these structures. Igneous differentiation of the intrusion could yield a range of lava compositions. Head and Wilson suggested a mechanism that would cause development of neutral buoyancy zones in the shallow subsurface of Venus, thereby tending to promote development of massive igneous intrusions.

  19. Late Proterozoic and Silurian alkaline plutons within the southeastern New England Avalon zone

    SciTech Connect

    Hermes, O.D. ); Zartman, R.E. )

    1992-07-01

    Distinct pulses of quartz-bearing, alkaline plutonism and volcanism are known to have occurred in the Avalon zone of southeastern New England during the Late Ordovician, Early Silurian, Devonian, and Carboniferous. Zircon separates from the Franklin and Dartmouth plutons demonstrate that two additional, previously unrecognized periods of alkaline magmatism occurred. The Franklin pluton yields an age of 417 {plus minus} 6 Ma (Late Silurian), whereas the Dartmouth pluton is Late Proterozoic (595 {plus minus} 5 Ma) and markedly older than the other plutons of alkaline affinity. The new ages further emphasize the episodic nature and long-term duration of such alkaline igneous events within the southeastern New England Avalon zone. The Dartmouth pluton may represent a post-collisional alkaline granite emplaced in the Late Proterozoic, almost immediately after a major period of calcalkaline igneous activity that accompanied plate convergence and continental accretion. The abrupt change from orogenic calcalkaline igneous activity to post-collisional alkaline granite, followed by younger episodes of anorogenic emplacement, is remarkably similar to igneous events reported from pan-African mobile belts widespread throughout Africa. In addition, parts of the Dartmouth pluton exhibit features indicative of mixing and commingling of felsic and mafic melts that are associated with coevally formed mylonitic fabrics. Because these fabrics are conformable to those in adjacent gneisses, but discordant with Alleghanian fabrics in the nearby Carboniferous Narragansett basin, they represent some of the best candidates for pre-Alleghanian structures thus far identified in the southeastern New England Avalon zone.

  20. MULTIPLE EPISODES OF IGNEOUS ACTIVITY, MINERALIZATION, AND ALTERATION IN THE WESTERN TUSHAR MOUNTAINS, UTAH.

    USGS Publications Warehouse

    Cunningham, Charles G.; Steven, Thomas A.; Campbell, David L.; Naeser, Charles W.; Pitkin, James A.; Duval, Joseph S.

    1984-01-01

    The report outlines the complex history of igneous activity and associated alteration and mineralization in the western Tushar Mountains, Utah and pointss out implciations for minerals exploration. The area has been subjected to recurrent episodes of igneous intrusion, hydrothermal alteration, and mineralization, and the mineral-resource potential of the different mineralized areas is directly related to local geologic history. The mineral commodities to be expected vary from one hydrothermal system to another, and from one depth to another within any given system. Uranium and molybdenum seem likely to have the greatest economic potential, although significant concentrations of gold may also exist.

  1. Application of remote sensing to the photogeologic mapping of the region of the Itatiaia alkaline complex. M.S. Thesis; [Minas Gerais, Rio De Janeiro, Sao Paulo, and Itatiaia, Brazil

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N. (Principal Investigator); Rodrigues, J. E.

    1981-01-01

    Remote sensing methods applied to geologically complex areas, through interaction of ground truth and information obtained from multispectral LANDSAT images and radar mosaics were evaluated. The test area covers parts of Minos Gerais, Rio De Janeiro and Sao Paulo states and contains the alkaline complex of Itatiaia and surrounding Precambrian terrains. Geological and structural mapping was satisfactory; however, lithological varieties which form the massif's could not be identified. Photogeological lineaments were mapped, some of which represent the boundaries of stratigraphic units. Automatic processing was used to classify sedimentary areas, which includes the talus deposits of the alkaline massifs.

  2. Genetic implications of minor-element and Sr-isotope geochemistry of alkaline rock complexes in the Wet Mountains area, Fremont and Custer counties, Colorado

    USGS Publications Warehouse

    Armbrustmacher, T.J.; Hedge, C.E.

    1982-01-01

    Concentrations of Rb, Sr, and REE (rare earth elements), and Sr-isotopic ratios in rocks of the Cambrian alkaline complexes in the Wet Mountains area, Colorado, show that rocks formed as end-products of a variety of magmas generated from different source materials. The complexes generally contain a bimodal suite of cumulus mafic-ultramafic rocks and younger leucocratic rocks that include nepheline syenite and hornblende-biotite syenite in the McClure Mountain Complex, nepheline syenite pegmatite in the Gem Park Complex, and quartz syenite in the complex at Democrat Creek. The nepheline syenite and hornblende-biotite syenite at McClure Mountain (535??5m.y.) are older than the syenitic rocks at Democrat Creek (511??8m.y.). REE concentrations indicate that the nepheline syenite at McClure Mountain cannot be derived from the hornblende-biotite syenite, which it intrudes, or from the associated mafic-ultramafic rocks. REE also indicate that mafic-ultramafic rocks at McClure Mountain have a source distinct from that of the mafic-ultramafic rocks at Democrat Creek. In the McClure Mountain Complex, initial87Sr/86Sr ratios for mafic-ultramafic rocks (0.7046??0.0002) are similar to those of hornblende-biotite syenite (0.7045??0.0002), suggesting a similar magmatic source, whereas ratios for carbonatites (0.7038??0.0002) are similar to those of nepheline syenite (0.7038??0.0002). At Democrat Creek, initial ratios of syenitic rocks (0.7032??0.0002) and mafic-ultramafic rocks (0.7028??0.0002) are different from those of corresponding rocks at McClure Mountain. ?? 1982 Springer-Verlag.

  3. Geology and porphyry copper-type alteration-mineralization of igneous rocks at the Christmas Mine, Gila County, Arizona

    USGS Publications Warehouse

    Koski, Randolph A.

    1979-01-01

    The Christmas copper deposit, located in southern Gila County, Arizona, is part of the major porphyry copper province of southwestern North America. Although Christmas is known for skarn deposits in Paleozoic carbonate rocks, ore-grade porphyry-type copper mineralization also occurs in a composite granodioritic intrusive complex and adjacent mafic volcanic country rocks. This study considers the nature, distribution, and genesis of alteration-mineralization in the igneous rock environment at Christmas. At the southeast end of the Dripping Spring Mountains, the Pennsylvanian Naco Limestone is unconformably overlain by the Cretaceous Williamson Canyon Volcanics, a westward-thinning sequence of basaltic volcanic breccia and lava flows, and subordinate clastic sedimentary rocks. Paleozoic and Mesozoic strata are intruded by Laramide-age dikes, sills, and small stocks of hornblende andesite porphyry and hornblende rhyodacite porphyry, and the mineralized Christmas intrusive complex. Rocks of the elongate Christmas stock, intruded along an east-northeast-trending fracture zone, are grouped into early, veined quartz diorite (Dark Phase), biotite granodiorite porphyry (Light Phase), and granodiorite; and late, unveined dacite porphyry and granodiorite porphyry. Biotite rhyodacite porphyry dikes extending east and west from the vicinity of the stock are probably coeval with biotite granodiorite porphyry. Accumulated normal displacement of approximately 1 km along the northwest-trending Christmas-Joker fault system has juxtaposed contrasting levels (lower, intrusive-carbonate rock environment and upper, intrusive-volcanic rock environment) within the porphyry copper system. K-Ar age determinations and whole-rock chemical analyses of the major intrusive rock types indicate that Laramide calc-alkaline magmatism and ore deposition at Christmas evolved over an extended period from within the Late Cretaceous (~75-80 m.y. ago) to early Paleocene (~63-61 m.y. ago). The sequence of

  4. Water oxidation with mononuclear ruthenium(II) polypyridine complexes involving a direct Ru(IV)═O pathway in neutral and alkaline media.

    PubMed

    Badiei, Yosra M; Polyansky, Dmitry E; Muckerman, James T; Szalda, David J; Haberdar, Rubabe; Zong, Ruifa; Thummel, Randolph P; Fujita, Etsuko

    2013-08-05

    The catalytic water oxidation mechanism proposed for many single-site ruthenium complexes proceeds via the nucleophilic attack of a water molecule on the Ru(V)═O species. In contrast, Ru(II) complexes containing 4-t-butyl-2,6-di-1',8'-(naphthyrid-2'-yl)-pyridine (and its bisbenzo-derivative), an equatorial water, and two axial 4-picolines follow the thermodynamically more favorable "direct pathway" via [Ru(IV)═O](2+), which avoids the higher oxidation state [Ru(V)═O](3+) in neutral and basic media. Our experimental and theoretical results that focus on the pH-dependent onset catalytic potentials indicative of a PCET driven low-energy pathway for the formation of products with an O-O bond (such as [Ru(III)-OOH](2+) and [Ru(IV)-OO](2+)) at an applied potential below the Ru(V)═O/Ru(IV)═O couple clearly support such a mechanism. However, in the cases of [Ru(tpy)(bpy)(OH2)](2+) and [Ru(tpy)(bpm)(OH2)](2+), the formation of the Ru(V)═O species appears to be required before O-O bond formation. The complexes under discussion provide a unique functional model for water oxidation that proceeds by four consecutive PCET steps in neutral and alkaline media.

  5. Igneous petrogenesis and tectonic setting of granitic rocks from the eastern Blue Ridge, Alabama Appalachians

    SciTech Connect

    Drummond, M.S. . Geology Dept.); Allison, D.T. . Geology Dept.); Tull, J.F. . Geology Dept.); Bieler, D.B. . Geology Dept.)

    1994-03-01

    A span of 150 my of orogenic activity is recorded within the granitic rocks of the eastern Blue Ridge of Alabama (EBR). Four discrete episodes of plutonism can be differentiated, each event exhibiting distinct field relations and geochemical signatures. (1) Penobscotian stage: this initial stage of plutonic activity is represented by the Elkahatchee Quartz Diorite (EQD), a premetamorphic (495 Ma) batholith and the largest intrusive complex (880 km[sup 2]) exposed in the Blue Ridge. Calc-alkaline I-type tonalite-granodiorite are the principal lithologies, with subordinate cumulate hbl-bt diorite, metadacite, granite and trondhjemite. The parental tonalitic magmas are interpreted to have been derived from a subducted MORB source under eclogite to get amphibolite conditions. (2) Taconic stage: the Kowaliga augen gneiss (KAG) and the Zana granite gneiss (ZG) are 460 Ma granitic bodies that reside in the SE extremity and structurally highest portion of the EBR. Both of these bodies are pre-metamorphic with strongly elongate sill- and pod-like shapes concordant with S[sub 1] foliation. Granite and granodiorite comprise the bulk of the KAG. (3) Acadian stage: Rockford Granite (RG), Bluff springs Granite (BSG, 366 Ma), and Almond Trondhjemite represent a suite of pre- to syn-metamorphic granitic intrusions. (4) late-Acadian stage: The Blakes Ferry pluton (BFP) is a post-kinematic pluton displaying spectacular by schlieren igneous flow structures, but no metamorphic fabric. The pluton's age can be bracketed between a 366 Ma age on the BSG and a 324 Ma K-Ar muscovite age on the BFP. BFP's petrogenesis has involved partial melting a MORB source followed by assimilation of metasedimentary host rock.

  6. Tectonic significance of Neoproterozoic magmatism of Nakora area, Malani igneous suite, Western Rajasthan, India

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Vallinayagam, G.

    2014-05-01

    Three magmatic phases are distinguished in the Neoproterozoic Nakora Ring Complex (NRC) of Malani Igneous Suite (MIS), namely (a) Extrusive (b) Intrusive and (c) Dyke phase. Magmatism at NRC initiated with minor amount of (basic) basalt flows and followed by the extensive/voluminous acid (rhyolites-trachytes) flows. The ripple marks are observed at the Dadawari area of NRC in tuffaceous rhyolite flow which suggests the aqueous condition of flows deposition. The emplacement of the magma appears to have been controlled by a well defined NE-SW tectonic lineament and cut by radial pattern of dykes. These NE-SW tectonic lineaments are the linear zones of crustal weakness and high heat flow. The spheroidal and rapakivi structures in the Nakora acid volcanics indicate the relationship between genetic link and magma mixing. Basalt-trachyte-rhyolite association suggests that the large amount of heat is supplied to the crust from the magma chamber before the eruption. The field (elliptical/ring structures), mineralogical and geochemical characteristics of Nakora granites attest an alkaline character in their evolution and consistent with within plate tectonic setting. The emplacement of these granites and associated volcanics is controlled by ring structures, a manifestation of plume activity and cauldron subsidence, an evidence of extensional tectonic environment. NRC granites are the product of partial melting of rocks similar to banded gneiss from Kolar Schist Belt of India. The present investigations suggest that the magmatic suites of NRC rocks are derived from a crustal source and the required heat supplied from a mantle plume.

  7. Is phosphorus predictably incompatible in igneous processes?

    NASA Technical Reports Server (NTRS)

    Goodrich, C. A.; Barnes, S.

    1984-01-01

    Siderophile element abundances are central to recent models for core formation in the Earth and Moon and the origin of the Moon. It is important to identify siderophile elements whose behavior in igneous processes is predictable, so that primary mantle abundances can be deduced by subtracting out the effects of igneous processes. Newsom's model for core formation in the Moon requires subchondritic P, and suggests that P was depleted due to volatility. Experiments were conducted to determine P olivine/liquid distribution coefficients. Preliminary results indicate that P can be compatible with olivine during rapid cooling, but is not during isothermal crystallization with long growth times, and tends to be expelled during annealing. It is therefore not likely that P is compatible under any widespread igneous conditions, and the incompatible behavior of P in lunar crustal rocks can be safety assumed. In addition, low fO2 is insufficient to cause P compatibility, so it is unlikely that P-rich silicates formed during the early evolution of the Earth or Moon. These results indicate that P is depleted in the Moon.

  8. Heteroleptic alkyl and amide iminoanilide alkaline earth and divalent rare earth complexes for the catalysis of hydrophosphination and (cyclo)hydroamination reactions.

    PubMed

    Liu, Bo; Roisnel, Thierry; Carpentier, Jean-François; Sarazin, Yann

    2013-09-27

    [{N^N}M(X)(thf)n] alkyl (X=CH(SiMe3)2) and amide (X=N(SiMe3)2) complexes of alkaline earths (M=Ca, Sr, Ba) and divalent rare earths (Yb(II) and Eu(II) ) bearing an iminoanilide ligand ({N^N}(-)) are presented. Remarkably, these complexes proved to be kinetically stable in solution. X-ray diffraction studies allowed us to establish size-structure trends. Except for one case of oxidation with [{N^N}Yb(II){N(SiMe3)2}(thf)], all these complexes are stable under the catalytic conditions and constitute effective precatalysts for the cyclohydroamination of terminal aminoalkenes and the intermolecular hydroamination and intermolecular hydrophosphination of activated alkenes. Metals with equal sizes across alkaline earth and rare earth families display almost identical apparent catalytic activity and selectivity. Hydrocarbyl complexes are much better catalyst precursors than their amido analogues. In the case of cyclohydroamination, the apparent activity decreases with metal size: Ca>Sr>Ba, and the kinetic rate law agrees with R(CHA) =k[precatalyst](1)[aminoalkene](1). The intermolecular hydroamination and hydrophosphination of styrene are anti-Markovnikov regiospecific. In both cases, the apparent activity increases with the ionic radius (Ca

  9. Magmatic Evolution of the Skye Igneous Center, Western Scotland

    NASA Astrophysics Data System (ADS)

    Fowler, S. J.; Bohrson, W. A.; Spera, F. J.

    2003-12-01

    Geochemically complex igneous suites are the result of interplay between deep and crustal-level processes. Quantitatively modeling the contribution that crustal-level processes such as magma recharge, crustal assimilation, and fractional crystallization have is critical for developing realistic models of how magma transport/storage systems evolve. The Energy-Constrained Recharge, Assimilation, and Fractional Crystallization simulator (EC-RAFC, Spera & Bohrson, 2001, 2002; Bohrson & Spera, 2001, 2003) provides a means to model thermal, compositional, and magma volume data for complex magmatic systems. The Skye igneous center, western Scotland, spanning the period 60.53 +/- 0.08 Ma - 53.5 +/- 0.8 Ma and characterized by a well-documented suite of lavas and intrusive rocks of picritic to granitic composition, is the first natural data set to which the EC-RAFC model has been applied in detail. Based on analysis of published field, stratigraphic, petrographic, and chemical data, we propose that the Skye Tertiary magmatic sequence be divided into four petrogenetically related lineages. EC-RAFC results indicate that each lineage is characterized by a unique parental magma that has undergone distinct episodes of RAFC. Model results, constrained by published data on the nature of the crust beneath Skye, indicate that the character of the assimilant changes upsection, suggesting that the associated magma reservoirs migrated to shallower levels as the magmatic system matured. The magmatic products of each group also record the fingerprint of multiple episodes of magma recharge, where the character of the recharge magma also evolves with time. The image of the magma transport system that emerges is one in which magma is initially intruded at lower crustal levels and undergoes a distinct RAFC episode. Residual magma from this event then migrates to shallower levels, where mid-crustal wallrock is assimilated; recharge magma is characterized by increasingly crustal chemical and

  10. Neodymium and Sr isotopic constraints on the petrogenetic relationships between carbonatites and cancrinite syenites from the Lueshe Alkaline Complex, east Zaire

    NASA Astrophysics Data System (ADS)

    Kramm, U.; Maravic, H. V.; Morteani, G.

    1997-07-01

    Field observations, petrographic investigations and age determinations on minerals of cancrinite syenites and carbonatites from the Lueshe Alkaline Complex, east Zaire, provide evidence for a spatial and temporal relationship of the two rock types. The Nd and Sr isotope compositions of these carbonatites and cancrinite syenites, however, reveal a genetic heterogeneity. In particular, the initial Sr data show a large variation in ɛ Sr (-15.9 to +33.8). ɛ Nd's vary from -1.33 to +0.10. Within the cancrinite syenites, a spatial variation in texture, as well as in mineral and chemical composition is observed. The rocks range from trachytoidal syenites found in the central part of the body to equigranular syenites with mosaic textures, which finally grade into carbosyenites when in contact with carbonatite. The variation in Sr isotope composition of this rock sequence (ɛ Sr: +4.7 to -10.5) is accompanied by an increase in the Ca and the Sr contents. This variation is interpreted as a fenitising effect imported on the syenites in situ by the carbonatite melts. Neglecting this late stage alteration of the syenites with its changing of the Sr isotope composition towards that of the carbonatites, the syenites become isotopically similar to the fenites. Therefore, a palingenetic origin for the cancrinite syenites involving rheomorphism of high-grade fenites which should have been similar in isotopic composition to the surrounding fenites of the Lueshe Complex is suggested.

  11. Stable Isotope Variability of Altered Sanidine Feldspars within the Bear Lodge Alkaline Intrusive Complex, Wyoming: Implications for Mineral Exploration Near a Late-Stage Carbonatite Ore Body

    NASA Astrophysics Data System (ADS)

    Mulvaney-Norris, J. L.; Larson, P. B.

    2015-12-01

    In a brecciated intrusive complex, mineral assemblages from non-ore-stage hydrothermal alteration may be mistakenly associated with ore body emplacement during exploration. The ability to differentiate mineralizing from non-mineralizing alteration by stable isotope analysis, and to map the fluid pathways, is a useful tool for future exploration. The Bull Hill diatreme, central Bear Lodge Mountains, contains porphyritic alkaline clasts and cross-cutting megacrystic sanidine trachyte dikes. The K feldspar (Kfs) phenocrysts reacted with and recorded the passage of hydrothermal fluids, likely derived from post-diatreme carbonatite intrusions. A study of the δ18O values of Kfs in the complex can assist mineralization mapping by revealing the late hydrothermal fluid pathways and provenance. Dike and breccia samples were split from three drill holes at regular distances, moving away from carbonatite dikes and large veins. Eighteen samples were prepared for oxygen isotope analysis by physical separation of megacrysts, or by crushing and hand-picking Kfs fragments from the breccia. A carbonatite Kfs sample was prepared by partial HCl digestion. Oxygen isotope ratios were measured at the Washington State University GeoAnalytical Laboratory using a Finnegan Delta S Mass Spectrometer. Kfs δ18O values range between 7.69‰ and 9.09‰ in the diatreme breccia xenocrysts, 5.28‰ to 8.12‰ in the megacrystic dike phenocrysts, and 7.15‰ in the carbonatite phenocrysts. Results suggest no clear relationship between the δ18O values in Kfs and the different phases of intrusion. This may be due to δ18O variability introduced by zoned and multi-crystal samples, limited variations of δ18O values among intrusion fluids, or that the final carbonatite intrusion pervasively altered all samples within the study area. Therefore, this method may not be particularly useful for identifying potential ore-bearing units in the Bear Lodge Intrusive Complex.

  12. Uranium in NIMROC standard igneous rock samples

    NASA Technical Reports Server (NTRS)

    Rowe, M. W.; Herndon, J. M.

    1976-01-01

    Results are reported for analysis of the uranium in multiple samples of each of six igneous-rock standards (dunite, granite, lujavrite, norite, pyroxenite, and syenite) prepared as geochemical reference standards for elemental and isotopic compositions. Powdered rock samples were examined by measuring delayed neutron emission after irradiation with a flux of the order of 10 to the 13th power neutrons/sq cm per sec in a nuclear reactor. The measurements are shown to compare quite favorably with previous uranium determinations for other standard rock samples.

  13. Magmas and magmatic rocks: An introduction to igneous petrology

    SciTech Connect

    Middlemost, E.A.K.

    1986-01-01

    This book melds traditional igneous petrology with the emerging science of planetary petrology to provide an account of current ideas on active magmatic and volcanic processes, drawing examples from all igneous provinces of the world as well as from the moon and planets. It reviews the history and development of concepts fundamental to modern igneous petrology and includes indepth sections on magmas, magnetic differentiation and volcanology.

  14. A novel chemiluminescence quenching method for determination of sulfonamides in pharmaceutical and biological fluid based on luminol-Ag(III) complex reaction in alkaline solution.

    PubMed

    Sun, Hanwen; Chen, Peiyun; Li, Liqing; Cheng, Peng

    2011-05-01

    A novel chemiluminescence (CL) quenching method for the determination of sulfonamides is proposed. The CL reaction between Ag(III) complex [Ag(HIO₆)₂]⁵⁻ and luminol in alkaline solution was investigated. The quenching effect of sulfonamides on CL emission of [Ag(HIO₆)₂]⁵⁻-luminol system was found. Quenching degree of CL emission was proportional to sulfonamide concentration. The effects of the reaction conditions on CL emission and quenching were examined. Under optimal conditions, the detection limits (s/n = 3) were 7.2, 17 and 8.3 ng/mL for sulfadiazine, sulfameter, and sulfadimethoxine, respectively. The recoveries of the three drugs were in the range of 91.3-110% with RSDs of 1.9-2.7% for urine samples, and 106-112% with RSDs of 1.6-2.8% for serum samples. The proposed method was used for the determination of sulfadiazine at clinically relevant concentrations in real urine and serum samples with satisfactory results.

  15. Northeast Atlantic Igneous Province volcanic margin development

    NASA Astrophysics Data System (ADS)

    Mjelde, R.; Breivik, A. J.; Faleide, J. I.

    2009-04-01

    Early Eocene continental breakup in the NE Atlantic Volcanic Province (NAIP) was associated with voluminous extrusive and intrusive magmatism, and initial seafloor spreading produced anomalously thick oceanic crust. Recent publications based on crustal-scale wide-angle seismic data show that there is a positive correlation between igneous crustal thickness (H) and average P-wave velocity (Vp) on all investigated margins in the NAIP. Vp can be used as a proxy for crustal composition, which can be related to the mode of mantle melting. A positive H-Vp correlation indicates that excessive mantle melting the first few million years after breakup was driven by an initial increased temperature that cools off as seafloor spreading develops, consistent with a mantle plume model. Variations in mantle composition can explain excess magmatism, but will generate a negative H-Vp correlation. Active mantle convection may increase the flux of mantle rocks through the melting zone above the rate of passive corner flow, which can also produce excessive magmatism. This would produce little H-Vp correlation, and place the curve lower than the passive flow melting curve in the diagram. We have compiled earlier published results with our own analyses of published and unpublished data from different groups to look for systematic variations in the mantle melting mode along the NAIP margins. Earlier studies (Holbrook et al., 2002, White et al, 2008) on the southeast Greenland conjugate system, indicate that the thick igneous crust of the southern NAIP (SE Greenland ? Hatton Bank) was dominated by increased mantle temperature only, while magmatism closer to the southern side of and including the Greenland-Iceland-Færøy Ridge (GIFR) was created by combined temperature increase and active mantle convection. Recent publications (Breivik et al., 2008, White et al, 2008) north of the GIFR for the Norway Basin segment, indicate temperature dominated magmatism between the Jan Mayen Fracture

  16. Reaction of the coordinate complexes of inositol hexaphosphate with first row transition series cations and Cd(II) with calf intestinal alkaline phosphatase.

    PubMed

    Martin, C J

    1995-05-01

    The reaction of alkaline phosphatase (APase) with the complexes of myo-inositol hexakisphosphate (IHP) and various cations at pH 7.2 results in a decrease in activity. Singly, neither IHP nor metal ions induce such changes. IHP-Mn(II) complexes were the least effective. Using the ions of nickel or cadmium, activity was reduced by > 95%. A similar large decrease (> 99%) was seen previously in the reaction of APase with IHP-Cu(II) complexes. With Co(II) and IHP as reactants, the activity was reduced to 10-12% of that of the native enzyme. When the apoprotein, prepared by reaction of the enzyme with either EDTA or 1,10-phenanthroline, was titrated with Co(II), the activity was equal to that resulting from the reaction of the enzyme with IHP-Co(II) complexes. Titration with zinc restored 95% of the original activity. The products are metal-substituted derivatives in which the resident catalytic (A-site) zinc ions, at least, are replaced by the cation of the IHP complex that was used. The rates of such reactions were fastest with the complexes of Cu(II) and Cd(II) (0.12 min-1), less so with Co(II) as the ion (0.056 min-1), and slowest with complexes of nickel and manganese (0.01 min-1). In every case, the rate of reaction, but not its extent of change, was inhibited by zinc ions that reduced rate constants to 0.0014-0.0054 min-1. Magnesium ions had no effect. Likewise, Mn(II), with but one exception, did not affect the reactions. When present along with IHP-Ni(II) complexes, the rate was increased and the enzyme activity further decreased. If Zn(II) was also present, this enhancement was eliminated. All changes in enzyme activity were reversible by treatment with EDTA followed by reconstitution with zinc. Approximately 95% conversion to the original activity could be attained. Reactivation of modified APase preparation also could be attained, in some cases, by pre-incubation with Zn(II) at pH 8. For example, conversion of the Cd(II)-substituted APase to the zinc enzyme

  17. Introduction to the Apollo collections. Part 1: Lunar igneous rocks

    NASA Technical Reports Server (NTRS)

    Mcgee, P. E.; Warner, J. L.; Simonds, C. H.

    1977-01-01

    The basic petrographic, chemical, and age data is presented for a representative suite of igneous rocks gathered during the six Apollo missions. Tables are given for 69 samples: 32 igneous rocks and 37 impactites (breccias). A description is given of 26 basalts, four plutonic rocks, and two pyroclastic samples. The textural-mineralogic name assigned each sample is included.

  18. Igneous rocks from Apollo 16 rake samples

    NASA Technical Reports Server (NTRS)

    Dowty, E.; Keil, K.; Prinz, M.

    1974-01-01

    Results are reported for a study of seven holocrystalline feldspathic rocks (including a spinel troctolite and six melt rocks) and one mare basalt clast from the Apollo-16 rake samples. The composition and grain structure of each rock is described in detail. Only the spinel troctolite is considered a good candidate for a primary igneous cumulate formed during the original differentiation of the lunar crust. It is shown that the melt rocks probably resulted from shock melting followed by rapid crystallization of heterogeneous highland material and that compositional variations are probably due to mixing of various amounts of heterogeneous cumulates and KREEP components. It is suggested that the mare basalt clast may have been derived from Mare Fecunditatis, although the nearest mare to the Apollo-16 site is Nectaris.

  19. Large igneous provinces linked to supercontinent assembly

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Santosh, M.; Luo, Zhaohua; Hao, Jinhua

    2015-04-01

    Models for the disruption of supercontinents have considered mantle plumes as potential triggers for continental extension and the formation of large igneous provinces (LIPs). An alternative hypothesis of top-down tectonics links large volcanic eruptions to lithospheric delamination. Here we argue that the formation of several LIPs in Tarim, Yangtze, Lhasa and other terranes on the Eurasian continent was coeval with the assembly of the Pangean supercontinent, in the absence of plumes rising up from the mantle transition zone or super-plumes from the core-mantle boundary. The formation of these LIPs was accompanied by subduction and convergence of continents and micro-continents, with no obvious relation to major continental rifting or mantle plume activity. Our model correlates LIPs with lithospheric extension caused by asthenospheric flow triggered by multiple convergent systems associated with supercontinent formation.

  20. The nakhlite meteorites: Augite-rich igneous rocks from Mars

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    2005-01-01

    analyses show mass-independent fractionations of S isotopes. Nitrogen and noble gases are complex and represent three components: two mantle sources (Chas-E and Chas-S), and fractionated Martian atmosphere. The nakhlites are igneous cumulate rocks, formed from basaltic magma at approx.1.3 Ga, containing excess crystals over what would form from pure magma. After accumulation of their augite and olivine crystals, they were affected (to various degrees) by crystallization of the magma, element diffusion among minerals and magma, chemical reactions among minerals and magma, magma movement among the crystals, and post-igneous chemical equilibration. The extent of these modifications varies, from least to greatest, in the order: MIL03346, NWA817, Y000593, Nakhla = Governador Valadares, Lafayette, and NWA998. Chemical, isotopic, and chronologic data confirm that the nakhlites formed on Mars, most likely in thick lava flows or shallow intrusions. Their crystallization ages, referenced to crater count chronologies for Mars, suggest that the nakhlites formed on the large volcanic constructs of Tharsis, Elysium, or Syrtis Major. The nakhlites were suffused with liquid water, probably at approx.620 ma. This water dissolved olivine and mesostasis glass, and deposited iddingsite and salt minerals in their places. The nakhlites were ejected from Mars at approx.10.75Ma by an asteroid impact and fell to Earth within the last 10,000 years. Although the nakhlites are enriched in incompatible elements, their source mantle was strongly depleted. This depletion event was ancient, as the nakhlites source mantle was fractionated while short-lived radionuclides (e.g., t(sub 1/2 = 9 my) were still active. This differentiation event may have been core formation coupled with a magma ocean, as is inferred for the moon.

  1. Number of Waste Package Hit by Igneous Intrusion

    SciTech Connect

    M. Wallace

    2004-10-13

    The purpose of this scientific analysis report is to document calculations of the number of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analyses include disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application (TSPA-LA) for the Yucca Mountain Project (YMP). Igneous activity is a disruptive event that is included in the TSPA-LA analyses. Two igneous activity scenarios are considered: (1) The igneous intrusion groundwater release scenario (also called the igneous intrusion scenario) considers the in situ damage to waste packages or failure of waste packages that occurs if they are engulfed or otherwise affected by magma as a result of an igneous intrusion. (2) The volcanic eruption scenario depicts the direct release of radioactive waste due to an intrusion that intersects the repository followed by a volcanic eruption at the surface. An igneous intrusion is defined as the ascent of a basaltic dike or dike system (i.e., a set or swarm of multiple dikes comprising a single intrusive event) to repository level, where it intersects drifts. Magma that does reach the surface from igneous activity is an eruption (or extrusive activity) (Jackson 1997 [DIRS 109119], pp. 224, 333). The objective of this analysis is to develop a probabilistic measure of the number of waste packages that could be affected by each of the two scenarios.

  2. Preliminary results, Central Gneiss Complex of the Coast Range batholith, southeastern Alaska: the roots of a high-K, calc-alkaline arc?

    USGS Publications Warehouse

    Barker, F.; Arth, Joseph G.

    1984-01-01

    The Central Gneiss Complex (CGC) of the Coast Range batholith is the oldest unit of the batholith east of Ketchikan, Alaska, being dated by the zircon UPb method (by T.W. Stern) at 128-140 Ma. Heterogeneous, layered, commonly migmatitic, orthogneiss of hornblende-biotite quartz diorite, tonalite, quartz monzodiorite and granodiorite compositions (IUGS terminology) form the major part of the CGC. These gneisses show a range of 50-65% SiO2 and are high in Al2O3 (c. 15-19%), K2O (1.5-4%) and Sr (800-900 ppm). Most major elements show coherent, typically magmatic trends with SiO2. La and Rb show maxima at ??? 58% SiO2. Initial 87Sr/86Sr ratios are relatively high and range from 0.7052 to 0.7066. Wallrocks of the CGC are mostly metagraywacke, pelite and metavolcanic rocks at amphibolite facies; they are geochemically dissimilar to the CGC. Major and minor elements of the CGC are very similar to those of high-K orogenic, calc-alkaline andesitic suites. The CGC may have formed largely by fractionation of mantle-derived, high AlKSr basaltic liquid in an ascending diapir, having hornblende, plagioclase, and biotite as major precipitating phases. The CGC probably represents the plutonic equivalent of a continental-margin or Andean arc that formed when the Taku terrane of the Insular belt on the west collided with the previously emplaced (but also allochthonous) Stikine terrane on the east in Late Jurassic or Early Cretaceous time. ?? 1984.

  3. On Some Feedback Relations Between Igneous Intrusion - Fluid flow - Metamorphic / Metasomatic Events and Deformation Events During low-P high-T Metamorphism. An Example From the Osor High Grade Complex (Catalan Coastal Ranges. NE Iberia)

    NASA Astrophysics Data System (ADS)

    Martínez, F. J.

    2004-05-01

    Bulk composition is an important factor that can influence both the rheologic and paragenetic histories of metamorphic rocks. Metasomatic changes are likely to occur in certain crustal levels from interplaying phenomena such as the intrusion and crystallization of magmatic bodies and also from pervasive or densely channelized fluid flow through these rocks during their metamorphic evolution. Accordingly, the following possibilities should be tested: a) The role of particular metasomatic changes in the sequence of mineral assemblages and mineral reactions; b) their role in changing deformation regimes and styles; c) their role in the location of major crustal tectonic features such as detachment shear zones, and d) their role in the onset and development of the exhumation histories of metamorphic complexes formed in medium and lower crustal levels during orogenesis. In the Osor Complex we have found evidence for fluid flow related to garnet growth during the prograde stage of a LP/HT metamorphic event and of fluid flow related to granitoid crystallization during the waning stages of regional metamorphic evolution. Fluid flow during increasing T was responsible for the modal deplection of the Osor metapelitic-metapsamitic rocks in quartz, plagioclase and muscovite, carrying away the SiO2, CaO and alcalis in solution. Local migmatization, with the generation of peraluminous granitoid lenses, took place during the final stages of this prograde process. Crystallization of granites was responsible for the recycling of K2O into the enclosing series and, as a result, growth of secondary blastic muscovite, biotite and albitic plagioclase occurred. Quartz deposition during retrogression also implies the recycling of SiO2 lost during the previous deplection stage, although in this case SiO2 concentrated locally, forming a set of quartz veins. The Osor rocks show the imprint of three main deformational events. D2 produced the dominant foliation, a penetrative crenulation

  4. Regional investigations of tectonic and igneous geology, Iran, Pakistan, and Turkey

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The author has identified the following significant results. An extension of the trace of the Chaman-Nushki fault was detected and delineated for 42 km, as was the Ornach-Nal fault for 170 km. Two structural intersections responsible for restricted movements in particular segments of the Chaman-Nushki fault were detected and interpreted. The newest and youngest fault named the Quetta-Mustung-Surab system was delineated for 580 km. The igneous complex of the Lasbela area was interpreted and differentiation was made between ultramafic complex, mafic complex, and basaltic lava flows. One oblong feature was also found which was interpreted as a porphyritic basalt plug.

  5. Igneous rock from Severnyi Kolchim (H3) chondrite: Nebular origin

    NASA Technical Reports Server (NTRS)

    Nazarov, M. A.; Brandstaetter, F.; Kurat, G.

    1993-01-01

    The discovery of lithic fragments with compositions and textures similar to igneous differentiates in unequilibrated ordinary chondrites (UOC's) and carbonaceous chondrites (CC's) has been interpreted as to suggest that planetary bodies existed before chondrites were formed. As a consequence, chondrites (except, perhaps CI chondrites) cannot be considered primitive assemblages of unprocessed nebular matter. We report about our study of an igneous clast from the Severnyi Kolchim (H3) chondrite. The results of the study are incompatible with an igneous origin of the clast but are in favor of a nebular origin similar to that of chondrules.

  6. Effect of igneous intrusive bodies on sedimentary thermal maturity

    SciTech Connect

    Wang, X.; Lerche, I.; Walter, C. )

    1989-09-01

    The high temperatures of igneous intrusives cause localized thermal maturity of sediments far in excess of the regional variation. Previous studies have shown that igneous bodies cool in less than about 1 million years for all but the most exceptional geological conditions. Three case studies are provided which show how the increase in thermal maturity around an igneous body can be used to assess the temperature of the intrusive at emplacement and also the time of intrusion. Corollative implications for localized hydrocarbon generation, migration, and accumulation are also discussed briefly.

  7. From birth to death of arc magmatism: The igneous evolution of Komandorsky Islands recorded tectonic changes during 50 Ma of westernmost Aleutian history

    NASA Astrophysics Data System (ADS)

    Höfig, T. W.; Portnyagin, M.; Hoernle, K.; Hauff, F. F.; van den Bogaard, P.; Garbe-Schoenberg, C.

    2013-12-01

    The Komandorsky Islands form the westernmost end of the Aleutian Island Arc. Four igneous complexes, spanning almost 50 Ma of magmatism, have previously been identified (Ivaschenko et al., 1984: Far East Scientific Centre, Vladivostok, 192 pp.). The petrogenesis of this protracted magmatic record and accurate absolute ages of events, however, remain poorly constrained. Our study investigates the relationship between magma composition and tectonic setting. The Komandorsky igneous basement formed in subduction zone setting. It hosts some of the oldest igneous rocks of the entire Aleutian Arc with the onset of magmatism occurring at 47 Ma. This early stage was characterized by classic fluid-dominated arc volcanism, which produced two coeval but likely genetically unrelated magmatic series of tholeiitic mafic and tholeiitic to calc-alkaline felsic rocks. To date, no boninites have been found and therefore arc initiation is different at the Aleutians than at Izu-Bonin-Marianas or the oldest rocks in the Aleutians have yet to be discovered. The prolonged production of the contrasting basalt-rhyolite association on Komandorsky Islands had lasted ~25 Ma and ceased around the Oligocene-Miocene boundary. Concurrently to this long-lasting activity, a gradual transition to a different mode of arc magmatism took place reflected by newly discovered Sr-enriched, HREE-depleted calc-alkaline basaltic andesitic lavas of mid-upper Eocene age spanning a time of at least ~7 Ma. This so-called Transition Series displays a moderate garnet signature marking the increased contribution of a slab-melt component to the magma sources of the Komandorsky Islands. Slab-melt contribution increased with decreasing age leading to strongly adakitic magmatism as early as ~33 Ma (Lower Oligocene), reflected by eruption of high-Sr (up to 2,500 ppm), highly HREE-depleted Adak-type magnesian basaltic andesites and andesites. These remarkable magmas became predominant during the Lower Miocene. They were

  8. On the weathering of Martian igneous rocks

    NASA Technical Reports Server (NTRS)

    Dreibus, G.; Waenke, H.

    1992-01-01

    Besides the young crystallization age, one of the first arguments for the martian origin of shergottite, nakhlite, and chassignite (SNC) meteorites came from the chemical similarity of the meteorite Shergotty and the martian soil as measured by Viking XRF analyses. In the meantime, the discovery of trapped rare gas and nitrogen components with element and isotope ratios closely matching the highly characteristic ratios of the Mars atmosphere in the shock glasses of shergottite EETA79001 was further striking evidence that the SNC's are martian surface rocks. The martian soil composition as derived from the Viking mission, with its extremely high S and Cl concentrations, was interpreted as weathering products of mafic igneous rocks. The low SiO2 content and the low abundance of K and other trace elements in the martian soils point to a mafic crust with a considerably smaller degree of fractionation compared to the terrestrial crust. However, the chemical evolution of the martian regolith and soil in respect to surface reaction with the planetary atmosphere or hydrosphere is poorly understood. A critical point in this respect is that the geochemical evidence as derived from the SNC meteorites suggests that Mars is a very dry planet that should have lost almost all its initially large water inventory during its accretion.

  9. Igneous intrusions in coal-bearing sequences

    SciTech Connect

    Gurevich, A.B.; Shishlov, S.B.

    1987-08-01

    Intrusions of various compositions, sizes, and shapes have been observed in 115 out of 620 coal basins or deposits on all the continents. They are mainly subvolcanic and hypabyssal, with depths of emplacement estimated as ranging from a few hundred meters to 6 km, but usually 3-4 km. Compositionally, 42% are basic, 31% intermediate, 23% acid, and 4% ultrabasic. Mafic (and related) rock types include dolerites, trachydolerites, gabbro-dolerites, gabbro-monzonites, monzonites, diabases, gabbrodiabases, and less often gabbros and basalts (subvolcanic bodies). These mafic intrusions occur in coal formations of various ages from Carboniferous through Neogene, but predominate in Paleozoic (47%) and Cenozoic beds (45%). They also occur in coal formations of all genetic types, apart from those on ancient stable platforms, where there are no signs of intrusive activity. The mafic intrusions are almost everywhere associated with comagmatic lavas and tuffs (mainly in the younger strata), and the coal beds themselves are to some extent enriched in pyroclastic material, particularly in the upper horizons. This paper gives a worldwide review of igneous intrusions in coal beds. 24 references.

  10. Evaporatic-source model for igneous-related Fe oxide (REE-Cu-Au-U) mineralization

    SciTech Connect

    Barton, M.D.; Johnson, D.A.

    1996-03-01

    We propose that many igneous-related Fe oxide-rich (REE-Cu-Au-U-bearing) deposits form by hydrothermal processes involving evaporitic ligand sources, either coeval salars or older evaporites. These deposits are abundant in both Phanerozoic and Proterozoic extensional continental and continent-margin settings. They commonly form in global arid zones, but they also occur where magmatism is superimposed upon older evaporites. Magmatic compositions exert only second-order control, mainly on alteration mineralogy and on element abundances. Hot S-poor brines generated by interaction with evaporitic materials are consistent with geologic settings and help rationalize the distinctive element enrichments (siderophile, lithophile) and hydrothermal alteration (sodic, locally alkaline) found in these systems. This model contrasts with immiscible oxide melt and magmatic-hydrothermal origins commonly proposed for these deposits, although all three mechanisms can occur. 31 refs., 3 figs., 1 tab.

  11. 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.

  12. Some Environmental Consequences of Large Igneous Provinces

    NASA Astrophysics Data System (ADS)

    Coffin, M. F.

    2009-12-01

    The formation of large igneous provinces (LIPs)—continental flood basalts, ‘volcanic’ margins, and oceanic plateaus—may impact the atmosphere, oceans, and biosphere by rapidly releasing huge amounts of particulates, magmatic volatiles (CO2, SO2, Cl, F, etc.), and potentially volatiles (CO2, CH4, SO2, etc.) from intruded sediments (e.g., carbonates, organic-rich shales, evaporites). A key factor affecting the magnitude of volatile release is whether eruptions are subaerial or marine; hydrostatic pressure inhibits vesiculation and degassing of relatively soluble volatile components (H2O, S, Cl, F) in deep water submarine eruptions, although low solubility components (CO2, noble gases) are mostly degassed even at abyssal depths. Directly or indirectly, such injections may cause changes in the atmosphere/ocean system that can lead to perturbations of atmosphere/ocean chemistry, circulation, ecology, and biological productivity. These changes can be global in extent, particularly if environmental conditions were at or near a threshold state or tipping point. LIPs may have been responsible for some of the most dramatic and rapid changes in the global environment. For example, between ~145 and ~50 Ma, the global ocean was characterized by chemical and isotopic variations (especially in C and Sr isotope ratios, trace metal concentrations, and biocalcification), relatively high temperatures, high relative sea level, episodic deposition of black shales (oceanic anoxic events), high production of hydrocarbons, mass extinctions of marine organisms, and radiations of marine flora and fauna. Temporal correlations between the intense pulses of igneous activity associated with LIP formation and environmental changes suggest more than pure coincidence. The 1783-84 eruption of Laki on Iceland provides the only historical record of the type of volcanism that constructs transient LIPs. Although Laki produced a basaltic lava flow representing only ~1% of the volume of a typical

  13. Charge Generation and Propagation in Igneous Rocks

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann

    2000-01-01

    Resistivity changes, ground potentials, electromagnetic (EM) and luminous signals prior to or during earthquakes have been reported, in addition to ground uplift and tilt, and to changes in the seismic wave propagation parameters. However, no physical model exists that ties these diverse phenomena together. Through time-resolved impacts experiments it has been observed that, when igneous rocks (gabbro, diorite, granite) are impacted at low velocities (approx. 100 m/sec), highly mobile electronic charge carriers are generated, spreading from a small volume near the impact point, causing electric potentials, EM and light emission. The rock becomes momentarily conductive. When impacted at higher velocities (approx. 1.5 km/sec), the propagation of the P and S waves is registered through the transient piezoelectric response of quartz. At the same time, the rock volume is filled with mobile charge carriers, and a positive surface potential is registered. During the next 1-2 msec the surface potential oscillates, due to electron injection from ground. These observations are consistent with positive holes, e.g. defect electrons in the O(2-) sublattice, that can travel via the O 2p-dominated valence band of the silicate minerals at the speed of a phonon-mediated charge transfer. Before activation, the positive hole charge carriers lay dormant in form of positive hole pairs, PHP, electrically inactive, chemically equivalent to peroxy links in the structures of constituent minerals. PHPs are introduced by way of hydroxyl (O3Si-OH) incorporated into nominally anhydrous minerals when they crystallize in water-laden environments. Given that sound waves of even relatively low intensity appear to cause PHPs dissociation, thus generating mobile positive holes, it is proposed that microfracturing during rock deformation cause PHP dissociation. Depending on where and how much the rock volume is stressed, the positive holes are expected to form fluctuating charge clouds in the

  14. On the Basic Principles of Igneous Petrology

    NASA Astrophysics Data System (ADS)

    Marsh, B. D.

    2014-12-01

    How and why Differentiation occurs has dominated Igneous Petrology since its beginning (~1880) even though many of the problems associated with it have been thoroughly solved. Rediscovery of the proverbial wheel with new techniques impedes progress. As soon as thin section petrography was combined with rock and mineral chemistry, rock diversity, compositional suites, and petrographic provinces all became obvious. The masterful 1902 CIPW norm in a real sense solved the chemical mystery of differentiation: rocks are related by the addition and subtraction of minerals in the anciently appreciated process of fractional crystallization. Yet few believed this, even after phase equilibria arrived. Assimilation, gas transfer, magma mixing, Soret diffusion, immiscibility, and other processes had strong adherents, even though by 1897 Becker conclusively showed the ineffectiveness of molecular diffusion in large-scale processes. The enormity of heat to molecular diffusion (today's Lewis no.) should have been convincing; but few paid attention. Bowen did, and he refined and restated the result; few still paid attention. And in spite of his truly masterful command of experiment and field relations in promoting fractional crystallization, Fenner and others fought him with odd arguments. The beauty of phase equilibria eventually dominated at the expense of knowing the physical side of differentiation. Bowen himself saw and struggled with the connection between physical and chemical processes. Progress has come from new concepts in heat transfer, kinetics, and slurry dynamics. The key approach is understanding the dynamic competition between spatial rates of solidification and all other processes. The lesson is clear: Scholarship and combined field, laboratory and technical expertise are critical to understanding magmatic processes. Magma is a limitlessly enchanting and challenging material wherein physical processes buttressed by chemistry govern.

  15. Alkaline rocks of Samchampi-Samteran, District Karbi-Anglong, Assam, India

    NASA Astrophysics Data System (ADS)

    Nag, S.; Sengupta, S. K.; Gaur, R. K.; Absar, A.

    1999-03-01

    The Samchampi-Samteran alkaline igneous complex (SAC) is a near circular, plug-like body approximately 12 km2 area and is emplaced into the Precambrian gneissic terrain of the Karbi Anglong district of Assam. The host rocks, which are exposed in immediate vicinity of the intrusion, comprise granite gneiss, migmatite, granodiorite, amphibolite, pegmatite and quartz veins. The SAC is composed of a wide variety of lithologies identified as syenitic fenite, magnetite ± perovskite ± apatite rock, alkali pyroxenite, ijolite-melteigite, carbonatite, nepheline syenite with leucocratic and mesocratic variants, phonolite, volcanic tuff, phosphatic rock and chert breccia. The magnetite ± perovskite ± apatite rock was generated as a cumulus phase owing to the partitioning of Ti, Fe at a shallow level magma chamber (not evolved DI = O1). The highly alkaline hydrous fluid activity indicated by the presence of strongly alkalic minerals in carbonatites and associated alkaline rocks suggests that the composition of original melt was more alkalic than those now found and represent a silica undersaturated ultramafic rock of carbonated olivine-poor nephelinite which splits with falling temperature into two immiscible fractions—one ultimately crystallises as alkali pyroxenite/ijolite and the other as carbonatite. The spatial distribution of varied lithotypes of SAC and their genetic relationships suggests that the silicate and carbonate melts, produced through liquid immiscibility, during ascent generated into an array of lithotypes and also reaction with the country rocks by alkali emanations produced fenitic aureoles (nephelinisation process). Isotopic studies (δ18O and δ13C) on carbonatites of Samchampi have indicated that the δ13C of the source magma is related to contamination from recycled carbon.

  16. Carbonatite and alkaline intrusion-related rare earth element deposits–A deposit model

    USGS Publications Warehouse

    Verplanck, Philip L.; Van Gosen, Bradley S.

    2011-01-01

    The rare earth elements are not as rare in nature as their name implies, but economic deposits with these elements are not common and few deposits have been large producers. In the past 25 years, demand for rare earth elements has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare earth elements come from only a few sources. China produces more than 95 percent of the world's supply of rare earth elements. Because of China's decision to restrict exports of these elements, the price of rare earth elements has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare earth elements deposits, and identifying and quantifying our nation's rare earth elements resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. 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 elements, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare earth elements, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.

  17. Petrological and Geochemical Studies of the Igneous Rocks at Cerro EL Borrego, Chihuahua, Mexico

    NASA Astrophysics Data System (ADS)

    Estrada, V. M.; Espejel-Garcia, V. V.; Villalobos-Aragon, A.

    2013-05-01

    Cerro El Borrego, which is a hill composed of igneous rocks, is located 13.7 km to the SW of Chihuahua city, in northern Mexico. The coordinates of the hill are 28° 11' 07'' N latitude and 105° 33' 23'' W longitude. The study area is within the Basin and Range Physiographic Province, characterized by a complex tectonic-structural pattern, such as elongated ranges with folds and igneous rock formations of Paleogene age. A lava flow of Oligocene age is part of the large volcanic and plutonic activity at the early times of the Cenozoic, which occurred to the NW portion of Mexico. In Cerro El Borrego, the rocks that outcrop are middle Oligocene's rhyolitic tuff to the NW of the hill, while to its SE there is a Pleistocene polymictic conglomerate. Previous work shows different interpretations about the origin and composition of the igneous rocks at Cerro El Borrego. This project includes whole rock and textural analyses, which helped to discern the petrogenesis of these rocks. Preliminary petrographic analyses indicate that the Cerro El Borrego, is a structural dome, and its feldspar-rich rocks contain large crystals that can be appreciated without a microscope. The presence of a porphyritic texture, suggest a sallow intrusion origin. A preliminary conclusion is that Cerro El Borrego is a shallow depth intrusive body with a syenitic composition derived from the Oligocene plutonic activity.

  18. Criticality Potential of Waste Packages Containing DOE SNF Affected by Igneous Intrusion

    SciTech Connect

    D.S. Kimball; C.E. Sanders

    2006-02-07

    The Department of Energy (DOE) is currently preparing an application to submit to the U.S. Nuclear Regulatory Commission for a construction authorization for a monitored geologic repository. The repository will contain spent nuclear fuel (SNF) and defense high-level waste (DHLW) in waste packages placed in underground tunnels, or drifts. The primary objective of this paper is to perform a criticality analysis for waste packages containing DOE SNF affected by a disruptive igneous intrusion event in the emplacement drifts. The waste packages feature one DOE SNF canister placed in the center and surrounded by five High-Level Waste (HLW) glass canisters. The effective neutron multiplication factor (k{sub eff}) is determined for potential configurations of the waste package during and after an intrusive igneous event. Due to the complexity of the potential scenarios following an igneous intrusion, finding conservative and bounding configurations with respect to criticality requires some additional considerations. In particular, the geometry of a slumped and damaged waste package must be examined, drift conditions must be modeled over a range of parameters, and the chemical degradation of DOE SNF and waste package materials must be considered for the expected high temperatures. The secondary intent of this calculation is to present a method for selecting conservative and bounding configurations for a wide range of end conditions.

  19. Amido-based potassium-alkaline earth metallates--synthesis and structures of heterobimetallic complexes of heavy s-block elements.

    PubMed

    Glock, Carsten; Görls, Helmar; Westerhausen, Matthias

    2011-08-28

    The metathesis reaction of potassium N-isopropylanilide with alkaline earth metal diiodides of calcium, strontium and barium in a molar ratio of 4:1 yields the corresponding alkaline earth metalates of the type [(THF)(n)K(μ-NPhiPr)(2)Ae(μ-NPhiPr)(2)K(THF)(n)] (1: Ae = Ca, n = 2). Stabilization and crystallization of such derivatives succeeds after exchange of the THF ligands by multidentate amino bases such as tetramethylethylenediamine (TMEDA) or pentamethyldiethylenetriamine (PMDETA). The influence of the size and hardness of the alkaline earth metal center on the molecular structures is studied with [(L)K(μ-NPhiPr)(2)Ae(μ-NPhiPr)(2)K(L)] (2: Ae = Ca, L = TMEDA; 3: Ae = Sr, L = TMEDA; 4: Ae = Sr, L = PMDETA; and 5: Ae = Ba, L = PMDETA). The molecular structures are dominated by (attractive and repulsive) electrostatic and steric factors leading to a shortening of the non-bonding AeK distances from calcium to barium.

  20. The Banhadão Alkaline Complex, Southeastern Brazil: source and evolution of potassic SiO2-undersaturated high-Ca and low-Ca magmatic series

    NASA Astrophysics Data System (ADS)

    Ruberti, Excelso; Enrich, Gaston E. R.; Azzone, Rogério G.; Comin-Chiaramonti, Piero; de Min, Angelo; Gomes, Celso B.

    2012-01-01

    The Cretaceous Banhadão alkaline complex in southeastern Brazil presents two potassic SiO2-undersaturated series. The high-Ca magmatic series consist of initially fractionated olivine (Fo92-91) + diopside (Wo48-43En49-35Ae0-7), as evidenced by the presence of xenocrysts and xenoliths. In that sequence, diopside (Wo47-38En46-37Ae0-8) + phlogopite + apatite + perovskite (Prv>92) crystallized to form the phlogopite melteigite and led to the Ca enrichment of the magma. Diopside (Wo47-41En32-24 Ae3-14) continued to crystallize as an early mafic mineral, followed by nepheline (Ne74.8-70.1Ks26.3-21.2Qz7.6-0.9) and leucite (Lc65-56) and subsequently by melanite and potassic feldspar (Or85-99Ab1-7) to form melanite ijolites, wollastonite-melanite urtites and melanite-nepheline syenites. Melanite-pseudoleucite-nepheline syenites are interpreted to be a leucite accumulation. Melanite nephelinite dykes are believed to represent some of the magmatic differentiation steps. The low-Ca magmatic series is representative of a typical fractionation of aegirine-augite (Wo36-29En25-4Ae39-18) + alkali feldspar (Or57-96Ab3-43) + nepheline (Ne76.5-69.0Ks19.9-14.4Qz15.1-7.7) + titanite from phonolite magma. The evolution of this series from potassic nepheline syenites to sodic sodalite syenites and sodalitolites is attributed to an extensive fractionation of potassic feldspar, which led to an increase of the NaCl activity in the melt during the final stages forming sodalite-rich rocks. Phonolite dykes followed a similar evolutionary process and also registered some crustal assimilation. The mesocratic nepheline syenites showed interactions with phlogopite melteigites, such as compatible trace element enrichments and the presence of diopside xenocrysts, which were interpreted to be due to a mixing/mingling process of phonolite and nephelinite magmas. The geochemical data show higher TiO2 and P2O5 contents and lower SiO2 contents for the high-Ca series and different LILE evolution trends

  1. Paleomagnetism of large igneous provinces: case-study from West Greenland, North Atlantic igneous province

    NASA Astrophysics Data System (ADS)

    Riisager, Janna; Riisager, Peter; Pedersen, Asger Ken

    2003-09-01

    We present new paleomagnetic and multi-model stereo photogrammetry data from lava sequences in the West Greenland part of the North Atlantic igneous province (NAIP). The joint analyses of paleomagnetic and photogrammetric data yield a well-defined paleomagnetic pole located at Lat=73.6°N, Long=160.5°E ( N=44, α95=6.2°, K=13.1; age ˜61-55 Ma), which is statistically indistinguishable from a pole recently obtained for the Eurasian part of the NAIP on Faroe Islands [Riisager et al., Earth Planet. Sci. Lett. 201 (2002) 261-276]. Combining the two datasets we obtain a joint NAIP paleomagnetic pole in Greenland coordinates: Lat=71.1°N, Long=161.1°E ( N=87, α95=4.3°, K=13.6; age ˜61-54 Ma). The results presented here represent the first study in which photogrammetry profiles were photographed at the exact same locations where paleomagnetic fieldwork was carried out, and a direct flow-to-flow comparison of the two datasets is possible. Photogrammetry is shown to be particularly useful because of (i) highly precise dip/strike measurements and (ii) detailed 'field observations' that can be made in the laboratory. Highly precise determination of the structural attitude of well-exposed Kanisut Mb lava sequences demonstrates that their apparently reliable in-field dip/strike measurements typically are up to ˜6° wrong. Erroneous dip/strike readings are particularly problematic as they offset paleomagnetic poles without affecting their confidence limits. Perhaps more important for large igneous provinces is the recognition of a variable temporal relationship between consecutive lava flows. We demonstrate how correct interpretation of paleosecular variation, facilitated by the detailed photogrammetry analysis, is crucial for the rapidly emplaced Vaigat Formation lavas. Inaccurate tectonic correction, non-averaged paleosecular variation and unrecognized excursional directions may, perhaps, explain why coeval paleomagnetic poles from large igneous provinces are often

  2. Calc-Alkaline magmatism associated with lithospheric extension in the Eocene and Miocene of the Pacific Northwest, U. S. A

    SciTech Connect

    Hooper, P.R.; Bailey, D.G.; Holder, G.A.M.; Urbanzcyk, K.M. . Dept. of Geology)

    1993-04-01

    A basic tenet of igneous petrology is that calc-alkaline suites are created in the subduction process and that extension is associated with alkalic and bimodal suites. Tectonic models of older terranes often use calc-alkaline suites as sure evidence of subduction. Eocene magmatism in the Pacific Northwest and Miocene volcanism associated with the northern limits of the Basin and Range province appear to contradict these tenets and so to raise reservations concerning their use in developing tectonic models. In northeast Washington State, extension in the Eocene is evidenced by gneissic core complexes and grabens. Recent precise dating of structures and magmatism (plutons, dikes and lavas) leaves no doubt that magmatism and extension are products of the same process. South of the Columbia Plateau, in the Miocene, the Powder River volcanic field consists of basalts, andesites, dacites and rhyolites erupted within the La Grande and Baker grabens; the magmatism clearly coincidental with graben development at ca. 14 Ma. Both basalts and more silicic flows have the typical subduction-related trace element signature. In neither province is progression from calc-alkaline to bimodal volcanism apparent. Both the Eocene and Miocene suites are associated with alkalic rocks. The authors suggest that in areas such as the western Cordillera extension causes the partial melting of sources which already carry the subduction-related signature. This could be crust (intermediate to more silicic magmas) or a depleted subcontinental mantle enriched during an earlier subduction event (basalts); that is, that while calc-alkaline rocks are associated with subduction, they may not require contemporaneous subduction, as is usually assumed.

  3. Rare gas isotopes and parent trace elements in ultrabasic-alkaline-carbonatite complexes, Kola Peninsula: identification of lower mantle plume component

    NASA Astrophysics Data System (ADS)

    Tolstikhin, I. N.; Kamensky, I. L.; Marty, B.; Nivin, V. A.; Vetrin, V. R.; Balaganskaya, E. G.; Ikorsky, S. V.; Gannibal, M. A.; Weiss, D.; Verhulst, A.; Demaiffe, D.

    2002-03-01

    During the Devonian magmatism (370 Ma ago) ˜20 ultrabasic-alkaline-carbonatite complexes (UACC) were formed in the Kola Peninsula (north-east of the Baltic Shield). In order to understand mantle and crust sources and processes having set these complexes, rare gases were studied in ˜300 rocks and mineral separates from 9 UACC, and concentrations of parent Li, K, U, and Th were measured in ˜70 samples. 4He/ 3He ratios in He released by fusion vary from pure radiogenic values ˜10 8 down to 6 × 10 4. The cosmogenic and extraterrestrial sources as well as the radiogenic production are unable to account for the extremely high abundances of 3He, up to 4 × 10 -9 cc/g, indicating a mantle-derived fluid in the Kola rocks. In some samples helium extracted by crushing shows quite low 4He/ 3He = 3 × 10 4, well below the mean ratio in mid ocean ridge basalts (MORB), (8.9 ± 1.0) × 10 4, indicating the contribution of 3He-rich plume component. Magnetites are principal carriers of this component. Trapped 3He is extracted from these minerals at high temperatures 1100°C to 1600°C which may correspond to decrepitation or annealing primary fluid inclusions, whereas radiogenic 4He is manly released at a temperature range of 500°C to 1200°C, probably corresponding to activation of 4He sites degraded by U, Th decay. Similar 4He/ 3He ratios were observed in Oligocene flood basalts from the Ethiopian plume. According to a paleo-plate-tectonic reconstruction, 450 Ma ago the Baltica (including the Kola Peninsula) continent drifted not far from the present-day site of that plume. It appears that both magmatic provinces could relate to one and the same deep-seated mantle source. The neon isotopic compositions confirm the occurrence of a plume component since, within a conventional 20Ne/ 22Ne versus 21Ne/ 22Ne diagram, the regression line for Kola samples is indistinguishable from those typical of plumes, such as Loihi (Hawaii). 20Ne/ 22Ne ratios (up to 12.1) correlate well with 40

  4. On some fundamentals of igneous petrology

    NASA Astrophysics Data System (ADS)

    Marsh, Bruce D.

    2013-09-01

    The age-old process of crystal fractionation leading to the diversity of the igneous rocks and Earth itself is an exceedingly well-understood chemical process in magmatism and physical chemistry. But the broader physical aspects of this and related processes have proven elusive on many fronts, especially in its relation to the spatial variations in rock composition, texture, and macroscopic features like layering. Magmatic systems, be they volcanic, dikes, sills, or plutons, are generally analyzed with a problem at hand and an end result in mind. The processes invoked to solve these problems, which are most often purely chemical, are often unique to each problem with few if any general principles emerging that are central to understanding the wider perspective of magmatic processes and problems. An attempt is made at the outset to provide a list of inviolate Magmatic First Principles that are relevant to analyzing most magmatic problems. These involve: initial conditions; critical crystallinity; solidification fronts; transport and emplacement fluxes; phenocrysts, xenocrysts, primocrysts; crystal size; layering and crystal sorting; thermal convection; magmatic processes are physical. Along with these principles, two reference magmatic systems are suggested where the initial conditions and outcome are unequivocal: the Sudbury impact melt sheet and the Hawaiian lava lakes. Sudbury formed in ~5 min by superheated magma crystallized to a near uniform sequence, while the tiny lava lakes, formed of crystal-laden slurries, form a highly differentiated layered sequence. The major difference is in the initial conditions of formation, especially the nature of the input materials. The challenge is to construct and analyze magmatic systems (i.e., magma chambers, sills, dikes, and lavas) using these reference end members and the suggested principles. The Hawaiian 500,000 year volcanic record exhibits what can be expected as input materials, namely a highly varied output of

  5. Oxidative mobilization of cerium and uranium and enhanced release of "immobile" high field strength elements from igneous rocks in the presence of the biogenic siderophore desferrioxamine B

    NASA Astrophysics Data System (ADS)

    Kraemer, Dennis; Kopf, Sebastian; Bau, Michael

    2015-09-01

    Polyvalent trace elements such as the high field strength elements (HFSE) are commonly considered rather immobile during low-temperature water-rock interaction. Hence, they have become diagnostic tools that are widely applied in geochemical studies. We present results of batch leaching experiments focused on the mobilization of certain HFSE (Y, Zr, Hf, Th, U and rare earth elements) from mafic, intermediate and felsic igneous rocks in the presence and absence, respectively, of the siderophore desferrioxamine B (DFOB). Our data show that DFOB strongly enhances the mobility of these trace elements during low-temperature water-rock interaction. The presence of DFOB produces two distinct features in the Rare Earths and Yttrium (REY) patterns of leaching solutions, regardless of the mineralogical and chemical composition or the texture of the rock type studied. Bulk rock-normalized REY patterns of leaching solutions with DFOB show (i) a very distinct positive Ce anomaly and (ii) depletion of La and other light REY relative to the middle REY, with a concave downward pattern between La and Sm. These features are not observed in experiments with hydrochloric acid, acetic acid or deionized water. In DFOB-bearing leaching solutions Ce and U are decoupled from and selectively enriched relative to light REY and Th, respectively, due to oxidation to Ce(IV) and U(VI). Oxidation of Ce3+ and U4+ is promoted by the significantly higher stability of the Ce(IV) and U(VI) DFOB complexes as compared to the Ce(III) and U(IV) DFOB complexes. This is similar to the relationship between the Ce(IV)- and Ce(III)-pentacarbonate complexes that cause positive Ce anomalies in alkaline lakes. However, while formation of Ce(IV) carbonate complexes is confined to alkaline environments, Ce(IV) DFOB complexes may produce positive Ce anomalies even in mildly acidic and near-neutral natural waters. Siderophore-promoted dissolution processes also significantly enhance mobility of other 'immobile' HFSE

  6. Development of a novel chemiluminescence method for the determination of cefazolin sodium in injectable powder and human urine based on a luminol-Cu(III) complex reaction in alkaline medium.

    PubMed

    Sun, Hanwen; Wang, Juan; Wang, Ting

    2013-01-01

    A novel chemiluminescence (CL) method was developed for the determination of cefazolin sodium based on the CL reaction between the [Cu(HIO6)2](5-) Cu(III) complex and luminol in alkaline solution. Results showed that CL emission of Cu(III) complex-luminol in alkaline medium was significantly different from that in acidic medium. A possible mechanism of the enhanced effect of cefazolin on CL emission of the [Cu(HIO6)2](5-)-luminol system was proposed. The effect of the reaction conditions on CL emissions was examined. Under optimized conditions, a good linear relationship was obtained between CL intensity and concentrations of cefazolin sodium in the range of 2.0 x 10(-8) to 2.0 x 10(-6) g/mL with a correlation coefficient of R(2) = 0.9978. The limit of detection was 4.58 x 10(-9) g/mL. The proposed method was applied for the determination of cefazolin sodium in real samples with recoveries of 82.0-109% with an RSD of 0.7-2.1%. The proposed method was successfully used for the determination of cefazolin sodium in injectable powder preparations and human urine with satisfactory results.

  7. Origin of igneous meteorites and differentiated asteroids

    NASA Astrophysics Data System (ADS)

    Scott, E.; Goldstein, J.; Asphaug, E.; Bottke, W.; Moskovitz, N.; Keil, K.

    2014-07-01

    Introduction: Igneously formed meteorites and asteroids provide major challenges to our understanding of the formation and evolution of the asteroid belt. The numbers and types of differentiated meteorites and non-chondritic asteroids appear to be incompatible with an origin by fragmentation of numerous Vesta-like bodies by hypervelocity impacts in the asteroid belt over 4 Gyr. We lack asteroids and achondrites from the olivine-rich mantles of the parent bodies of the 12 groups of iron meteorites and the ˜70 ungrouped irons, the 2 groups of pallasites and the 4--6 ungrouped pallasites. We lack mantle and core samples from the parent asteroids of the basaltic achondrites that do not come from Vesta, viz., angrites and the ungrouped eucrites like NWA 011 and Ibitira. How could core samples have been extracted from numerous differentiated bodies when Vesta's basaltic crust was preserved? Where is the missing Psyche family of differentiated asteroids including the complementary mantle and crustal asteroids [1]? Why are meteorites derived from far more differentiated parent bodies than chondritic parent bodies even though C and S class chondritic asteroids dominate the asteroid belt? New paradigm. Our studies of meteorites, impact modeling, and dynamical studies suggest a new paradigm in which differentiated asteroids accreted at 1--2 au less than 2 Myr after CAI formation [2]. They were rapidly melted by 26Al and disrupted by hit-and-run impacts [3] while still molten or semi-molten when planetary embryos were accreting. Metallic Fe-Ni bodies derived from core material cooled rapidly with little or no silicate insulation less than 4 Myr after CAI formation [4]. Fragments of differentiated planetesimals were subsequently tossed into the asteroid belt. Meteorite evidence for early disruption of differentiated asteroids. If iron meteorites were samples of Fe-Ni cores of bodies that cooled slowly inside silicate mantles over ˜50--100 Myr, irons from each core would have

  8. Anodes for alkaline electrolysis

    DOEpatents

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  9. The Kenna ureilite - An ultramafic rock with evidence for igneous, metamorphic, and shock origin

    NASA Technical Reports Server (NTRS)

    Berkley, J. L.; Brown, H. G.; Keil, K.; Carter, N. L.; Mercier, J.-C. C.; Huss, G.

    1976-01-01

    Ureilites are a rare group of achondrites. They are composed mainly of olivine and pigeonite in a matrix of carbonaceous material, including graphite, lonsdaleite, diamond, and metal. In most respects Kenna is a typical ureilite with the requisite mineralogical and chemical properties of the group. Differences of the Kenna ureilite from previously studied ureilites are related to a greater density, the occurrence of exceedingly minute quantities of feldspar, and a very strong elongation lineation of the silicate minerals. A description is presented of a study which indicates a complex history for Kenna, including igneous, mild metamorphic, and shock processes.

  10. Uranium and other element analyses of igneous rocks of Arkansas

    SciTech Connect

    Steele, K.F.

    1982-05-01

    Seventy-six samples of igneous rocks representing a variety of rock types and locations in Arkansas were analyzed by neutron activation analysis for the elements U, Th, Na, Al, Sc, Ti, V, Mn, Fe, La, Ce, Sm, Eu, Dy, Yb, Lu, and Hf. Samples were collected from the major igneous intrusions at Granite Mountain, Bauxite, Magnet Cove, Potash Sulfur Springs, and Murfreesboro, representing various syenites, lamprophyres, carbonatite, kimberlite, and periodotite. To make the data available for public use without further delay, this report is being issued without the normal technical and copy editing.

  11. Igneous Petrogenesis of Tequila Volcano, Western Mexico

    NASA Astrophysics Data System (ADS)

    Vázquez-Duarte, A.; Gómez-Tuena, A.; Díaz-Bravo, B.

    2011-12-01

    Tequila volcano belongs to a Quaternary volcanic chain that runs in parallel to the Middle American Trench, but that have been constructed within the so-called Tepic-Zacoalco rift: an extensional tectonic structure that has been active for the past 3.5 Ma. This unusual tectonic setting, and the existence of a high-resolution stratigraphy for the Tequila Volcanic Field (Lewis-Kenedi, 2005, Bull Volcanol), provide an excellent opportunity to study andesite petrogenesis. New comprehensive geochemical data allow the recognition of at least four different magmatic series around Tequila: 1) The Santa Rosa intraplate basalts (1.0 - 0.2 Ma), a volcanic plateau constructed along the Santiago River Fault north of Tequila volcano. These Na-alkaline basalts are olivine-phyric, have negligible subduction signatures (Ba/Nb= 11.75 - 49.36), and display Sr-Nd-Pb isotopic compositions that correlate with fractionation indexes, probably indicating melt-crust interactions. 2) A group of vitreous domes and flows of dacitic to rhyolitic compositions, mostly contemporaneous to the Santa Rosa basalts, that were emplaced on the periphery of Tequila volcano. These rocks can have very low Sr and Eu contents but their isotopic compositions are remarkably constant and similar to the Santa Rosa basalts, probably indicating a genetic link through low pressure fractionation in the stability field of plagioclase. 3) The main edifice of Tequila volcano (~0.2 Ma) is made of two pyroxene andesites and dacites with strong subduction signatures (Ba/Nb= 53-112), that inversely correlate with MgO contents, but that follow a diverging evolutionary trend as the rest of the sequences. The isotopic compositions of Tequila main edifice can extend to slightly more enriched values, but do not correlate with fractionation indexes, thus indicating provenance from a different source. 4) The youngest activity on Tequila volcano (~0.09 Ma) is represented by amphibole bearing andesites that erupted through the

  12. Characterization of Arctic Highly Magnetic Domains - the Geophysical Expression of Inferred Large Igneous Province(s)

    NASA Astrophysics Data System (ADS)

    Saltus, R. W.; Oakey, G.; Miller, E. L.; Jackson, R.

    2012-12-01

    The magnetic anomalies of the high arctic are dominated by a large domain (1000 x 1700 km; the High Arctic Magnetic High, HAMH) consisting of numerous high-amplitude magnetic high ridges with a complex set of orientations and by other smaller, but still fundamentally highly magnetic, domains. The magnetic potential anomaly field (also known as pseudogravity) of the HAMH shows a single large intensity high and underscores the crustal-scale thickness of this geophysical feature (which also forms a prominent anomaly on satellite magnetic maps). The seafloor morphology of this region includes the complex linear trends of the Alpha and Mendeleev ridges, but the magnetic expression of this domain extends beyond the complex bathymetry to include areas where Canada Basin sediments have covered the complex basement topography. The calculated magnetic effect of the bathymetric ridges matches some of the observed magnetic anomalies, but not others. We have analyzed and modeled the distinctive HAMH and other smaller magnetic high domains to generate estimates of their volume and to characterize the directionality of their component features. Complimentary processing and modeling of high arctic gravity anomalies allows characterization of the density component of these geophysical features. Spatially, the HAMH encompasses the Alpha and Mendeleev "ridges," that are considered to represent a major mafic igneous province. The term "Alpha-Mendeleev Large Igneous Province" is given to a domain mapped by tracing magnetic anomalies in a recent map published by AAPG (Grantz and others, 2009). On this map the province is described as "alkali basalt with ages between 120 and 90 Ma". New seismic and bathymetric data, collected as part of on-going research efforts for definition of extended continental shelf, are revealing new details about the Alpha ridge. One interesting development is the possible identification of a supervolcano that may represent a major locus of igneous activity. In

  13. Synthesis, crystal structure and investigation of mononuclear copper(II) and zinc(II) complexes of a new carboxylate rich tripodal ligand and their interaction with carbohydrates in alkaline aqueous solution.

    PubMed

    Stewart, Christopher D; Pedraza, Mayra; Arman, Hadi; Fan, Hua-Jun; Schilling, Eduardo Luiz; Szpoganicz, Bruno; Musie, Ghezai T

    2015-08-01

    A new carboxylate rich asymmetric tripodal ligand, N-[2-carboxybenzomethyl]-N-[carboxymethyl]-β-alanine (H3camb), and its di-copper(II), (NH4)2[1]2, and di-zinc(II), ((CH3)4N)2[2]2, complexes have been synthesized as carbohydrate binding models in aqueous solutions. The ligand and complexes have been fully characterized using several techniques, including single crystal X-ray diffraction. The interactions of (NH4)2[1]2 and ((CH3)4N)2[2]2 with D-glucose, D-mannose, D-xylose and xylitol in aqueous alkaline media were investigated using UV-Vis and (13)C-NMR spectroscopic techniques, respectively. The molar conductance, NMR and ESI-MS studies indicate that the complexes dissociate in solution to produce the respective complex anions, 1(-) and 2(-). Complexes 1(-) and 2(-) showed chelating ability towards the naturally abundant and biologically relevant sugars, D-glucose, D-mannose, D-xylose, and xylitol. The complex ions bind to one molar equivalent of the sugars, even in the presence of stoichiometric excess of the substrates, in solution. Experimentally obtained spectroscopic data and computational results suggest that the substrates bind to the metal center in a bidentate fashion. Apparent binding constant values, pK(app), between the complexes and the substrates were determined and a specific mode of substrate binding is proposed. The pK(app) and relativistic density functional theory (DFT) calculated Gibbs free energy values indicate that D-mannose displayed the strongest interaction with the complexes. Syntheses, characterizations, detailed substrate binding studies using spectroscopic techniques, single crystal X-ray diffraction and geometry optimizations of the complex-substrates with DFT calculations are also reported.

  14. Band gaps and photocurrent responses of two novel alkaline earth metal(II) complexes based on 4,5-di(4‧-carboxylphenyl)benzene

    NASA Astrophysics Data System (ADS)

    Meng, Jiang Ping; Yan, Zhi Shuo; Long, Ji Ying; Gong, Yun; Lin, Jian Hua

    2017-01-01

    By using a rigid dicarboxylate ligand, 4,5-di(4‧-carboxylphenyl)benzene (H2L), two complexes formulated as SrL(DMF)(H2O)·(CH3CN) (DMF=N,N‧-dimethylformamide) (1) and BaL(H2O)2 (2) were solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1 and 2 display two-dimensional (2D) layer structures. The two complexes exhibit different electrochemical and photoelectrochemical properties. Their thermal stabilities, cyclic voltammograms, UV-vis absorption and diffuse reflectance spectra and photoluminescence properties have been investigated. The band structures, the total density of states (TDOS) and partial density of states (PDOS) of the two complexes were calculated by CASTEP program. Complex 2 exhibits much higher photocurrent density than complex 1. The Mott-Schottky plots reveal that complexes 1 and 2 both are p-type semiconductors, which are in agreement with their band structure calculations.

  15. Winter Ice and Snow as Models of Igneous Rock Formation.

    ERIC Educational Resources Information Center

    Romey, William D.

    1983-01-01

    Examines some features of ice and snow that offer teachers and researchers help in understanding many aspects of igneous processes and configurations. Careful observation of such processes as melting, decay, evolution, and snow accumulation provide important clues to understanding processes by which many kinds of rocks form. (Author/JN)

  16. The Formation of Igneous CAIs and Chondrules by Impacts?

    NASA Technical Reports Server (NTRS)

    Connolly, Harold C., Jr.; Love, Stanley G.

    2001-01-01

    Numerous challenges exist with forming the igneous spheres found within chondrites via collision events in the early solar nebula. We explore these challenges and discuss potential methods to overcome them. Collision models should be received cautiously. Additional information is contained in the original extended abstract.

  17. Igneous fractionation and subsolidus equilibration of diogenite meteorites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.

    1993-01-01

    Diogenites are coarse-grained orthopyroxenite breccias of remarkably uniform major element composition. Most diogenites contain homogeneous pyroxene fragments up to 5 cm across of Wo2En74Fs24 composition. Common minor constituents are chromite, olivine, trolite and metal, while silica, plagioclase, merrillite and diopside are trace phases. Diogenites are generally believed to be cumulates from the eucrite parent body, although their relationship with eucrites remains obscure. It has been suggested that some diogenites are residues after partial melting. I have performed EMPA and INAA for major, minor and trace elements on most diogenites, concentrating on coarse-grained mineral and lithic clasts in order to elucidate their igneous formation and subsequent metamorphic history. Major element compositions of diogenites are decoupled from minor and trace element compositions; the latter record an igneous fractionation sequence that is not preserved in the former. Low equilibration temperatures indicate that major element diffusion continued long after crystallization. Diffusion coefficients for trivalent and tetravalent elements in pyroxene are lower than those of divalent elements. Therefore, major element compositions of diogenites may represent means of unknown portions of a cumulate homogenized by diffusion, while minor and trace elements still yield information on their igneous history. The scale of major element equilibration is unknown, but is likely to be on the order of a few cm. Therefore, the diogenite precursors may have consisted largely of cm-sized, igneously zoned orthopyroxene grains, which were subsequently annealed during slow cooling, obliterating major element zoning but preserving minor and trace incompatible element zoning.

  18. Alkaline battery operational methodology

    DOEpatents

    Sholklapper, Tal; Gallaway, Joshua; Steingart, Daniel; Ingale, Nilesh; Nyce, Michael

    2016-08-16

    Methods of using specific operational charge and discharge parameters to extend the life of alkaline batteries are disclosed. The methods can be used with any commercial primary or secondary alkaline battery, as well as with newer alkaline battery designs, including batteries with flowing electrolyte. The methods include cycling batteries within a narrow operating voltage window, with minimum and maximum cut-off voltages that are set based on battery characteristics and environmental conditions. The narrow voltage window decreases available capacity but allows the batteries to be cycled for hundreds or thousands of times.

  19. Geochemistry of Rock Samples Collected from the Iron Hill Carbonatite Complex, Gunnison County, Colorado

    USGS Publications Warehouse

    Van Gosen, Bradley S.

    2008-01-01

    A study conducted in 2006 by the U.S. Geological Survey collected 57 surface rock samples from nine types of intrusive rock in the Iron Hill carbonatite complex. This intrusive complex, located in Gunnison County of southwestern Colorado, is known for its classic carbonatite-alkaline igneous geology and petrology. The Iron Hill complex is also noteworthy for its diverse mineral resources, including enrichments in titanium, rare earth elements, thorium, niobium (columbium), and vanadium. This study was performed to reexamine the chemistry and metallic content of the major rock units of the Iron Hill complex by using modern analytical techniques, while providing a broader suite of elements than the earlier published studies. The report contains the geochemical analyses of the samples in tabular and digital spreadsheet format, providing the analytical results for 55 major and trace elements.

  20. Empirical equation for igneous calcic amphibole geobarometry

    SciTech Connect

    Hammarstrom, J.M.; Zen, E.

    1985-01-01

    The octahedral (Al/sup vi/) aluminum content of amphibole (am) is frequently cited as a pressure sensitive parameter. A positive correlation between total (Al/sup T/) and tetrahedral (Al/sup lv/) aluminum, defined by a single linear trend, is observed for calcic am from 6 calc-alkalic tonalite- and granodiorite-dominant plutonic complexes which have similar 1) mineral assemblages, 2) bulk composition, 3) crystallization temperature ranges, and 4) oxygen fugacities. The 6 complexes vary from 1 to 8-10 kbar in estimated pressure (P) of emplacement based on one or more of the following criteria: associated regional/contact metamorphism, reconstructed overburden, cooling history, presence of magmatic epidote, and/or grossular-almandine garnet, and presence of miarolites. Am from each complex are compositionally variable, largely due to the strong dependence of Al/sup iv/ on temperature; e.g., Al/sup T/ values, calculated for 23 oxygens per formula unit, range from 0.6 to 1.8 and 1.7 to 2.7 in complexes with estimated emplacement pressures of 2 and 8 kbar, respectively. The entire range of microprobe analyses from these complexes and others indicate this empirical geobarometer: P (kbar) = -3.89 + 5.04 Al/sup T/, +/- 2 kbar standard error on the pressure estimate. Al/sup T/ is preferred over Al/sup vi/ as the independent parameter because it is not a difference between two large numbers, and is less sensitive to errors in site assignments and ferric iron estimates from microprobe data.

  1. CO2-dependent fractional crystallization of alkaline silicate magmas and unmixing of carbonatites within the intrusive complexes of Brava Island (Cape Verde)

    NASA Astrophysics Data System (ADS)

    Weidendorfer, D.; Schmidt, M. W.; Mattsson, H. B.

    2014-12-01

    Intrusive carbonatites often occur in intimate association with SiO2-undersaturated rocks such as melilitites, nephelinites, syenites and phonolites. The occurrence of carbonatites on five of the 10 main islands of the Cape Verde hotspot argues for a CO2-enriched mantle source. Whether alkali-poor carbonatites on the Cape Verdes directly represent small mantle melt fractions or form by extreme fractionation and/or liquid immiscibility from a CO2-rich silicate magma remains a matter of debate. This study focuses on the pyroxenites, nephelinites, ijolites, syenites, phonolites and carbonatites of the intrusive unit of Brava Island. This relative complete series allows for the deduction of a CO2-dependent fractionation pathway from the most primitive basanitic dikes towards phonolitic compositions through an ijolitic series. Major and trace element whole rock and mineral composition trends can be reproduced by fractionating a sequence of olivine, augite, perovskite, biotite, apatite, sodalite and FeTi-oxides, present as phenocrysts in the rocks corresponding to their fractionation interval. To reproduce the observed chemistry of the alkaline silicate rocks a total fractionation of ~87% is required. The melts evolve towards the carbonatite-silicate miscibility gap, an initial CO2 of 0.5 wt% would be sufficient to maintain CO2-saturation in the more evolved compositions. The modelled carbonatite compositions, conjugate to nepheline-syenites to phonolites, correspond well to the observed ones except for an alkali-enrichment with respect to the natural samples. The alkali-depleted nature of the small carbonatite intrusions and dikes on Brava is likely a consequence of fluid-release to the surrounding wall-rocks during crystallization, where fenitization can be observed. The trace element chemistry of primary carbonates and also cpx within both, the carbonatites and the associated silicate rocks, substantiates our fractionation model. Furthermore, carbonatite and silicate

  2. Magnetic petrofabric of igneous rocks: Lessons from pyroclastic density current deposits and obsidians

    NASA Astrophysics Data System (ADS)

    Cañón-Tapia, E.; Mendoza-Borunda, R.

    2014-12-01

    Measurement of the anisotropy of magnetic susceptibility (AMS) of igneous rocks can provide clues concerning their mechanism of formation and in particular are very helpful as flow direction indicators. Unlike other igneous rocks, however, pyroclastic density current deposits (PDCDs) present a challenge in the interpretation of AMS measurements due to the complexity of their mechanism of emplacement. In this paper we review the most common assumptions made in the interpretation of the AMS of PDCD, taking advantage of key lessons obtained from obsidians. Despite the complexities on the mechanism of formation of PDCDs, it is shown that a key element for the fruitful interpretation of AMS is to give proper attention to the various components likely to be involved in controlling their general petrofabric. The anisotropies of ferromagnetic crystals (whether as free phases or embedded within clasts or shards), and those of paramagnetic minerals (mainly ferrosilicates) need to be taken into consideration when interpreting the AMS measurements of PDCDs. Variations of the deposition regime both as a function of position and of time also need to be considered on the interpretations. Nevertheless, if a suitable sampling strategy is adopted, the potential of the AMS method as a petrofabric indicator is maximized.

  3. Magmatism and Eurekan deformation in the High Arctic Large Igneous Province: Age and geological constraints from North Greenland

    NASA Astrophysics Data System (ADS)

    Tegner, C.; Storey, M.; Holm, P. M.; Thorarinsson, S. B.; Zhao, X.; Tappe, S.; Heaman, L.; Knudsen, M. F.

    2013-12-01

    Age, compositional and geological data show the High Arctic Large Igneous Province is unusual on two counts: first, magmatism was prolonged and include an initial tholeiitic phase (130-80 Ma) and a second alkaline phase (85-60 Ma); second, it was subsequently deformed during the Eurekan orogeny. New 40Ar-39Ar and U-Pb dating provides emplacement ages of 71-68 Ma for most of the Kap Washington alkaline volcanics of North Greenland, but with activity continuing down to 61 Ma. A thermal resetting age of 49-47 Ma is also identified in 40Ar-39Ar whole-rock data for trachyte flows. Patch perthite feldspars and coeval resetting of Rb-Sr isotopes by hydrothermal fluids provide further support for thermal overprinting, interpreted as a result of Eurekan compressional tectonism. The formation of the tholeiitic suite (130-80 Ma) appears to be associated with the opening of the Canada Basin and may have involved mantle plume action. Formation of the alkaline suite (85-60 Ma) is attributed to continental rifting in the Lincoln Sea area linked to seafloor spreading in the Labrador Sea and the Baffin Bay. The alkaline and tholeiitic suites of the High Arctic may therefore be unrelated. It is striking that High Arctic volcanism terminates at about the same time (c. 60 Ma) as magmatism in the North Atlantic Large Igneous Province begins. We suggest this is a corollary of a change from extensional to compressional tectonism in the High Arctic. In the period when Greenland moved together with Eurasia (>60 Ma), the separation from North America resulted in rift-related alkaline magmatism in the High Arctic. When Greenland subsequently moved as a separate plate (60-35 Ma), overlapping spreading on both sides pushed it northwards and volcanism in the High Arctic stopped due to compression. Evaluation of plate kinematic models shows that the relative northwards movement of Greenland culminated in the Eocene, coinciding with thermal resetting. We conclude that compression in North

  4. Did North Atlantic Igneous Province igneous sills trigger or maintain Paleocene Eocene Thermal Maximum global warming?

    NASA Astrophysics Data System (ADS)

    Fernandes, Karina; Jones, Stephen M.; Schofield, Nick; Clayton, Geoff

    2010-05-01

    Igneous sills of the North Atlantic Igneous Province (NAIP) were intruded into organic-rich sediments, generating methane and carbon dioxide by thermal maturation. These greenhouse gases escaped to the ocean and atmosphere through hydrothermal vents above the sills that have been observed on seismic reflection data and by drilling. It has been suggested that the NAIP sills provided a significant component of the greenhouse gases that forced warming during the Paleocene Eocene Thermal Maximum (PETM). Here we consider whether methane released by NAIP sills could have triggered, as well as maintained, the PETM warming. Warming resulting from the PETM trigger began a few thousand years before the major upheaval in the carbon cycle that was associated with the PETM itself. Recent organic geochemical investigations have suggested that methane was involved in the trigger. Since the lifetime of methane in the atmosphere was approximately one decade during the Paleocene, the triggering methane pulse probably contained on the order of 100 Gt or more of carbon and was probably released in a period of c. 10 years or less. We use recent field observations of fluidized country rocks around sills to speculate on a model for sill emplacement, greenhouse gas generation and escape. The observation of fluidized sediments associated with lobe and finger structures along inward-dipping sections of many sills suggests that these sill rims propagated laterally by fluidizing a restricted volume of country rock, allowing the magma to advance into the fluidized region as a viscous fingering front. At this stage, the fluidized region was not connected to the surface by a conduit, so greenhouse gases could not escape rapidly. Eventually, as the sill rim propagated laterally and upward, a hydrothermal conduit was initiated and propagated rapidly upward to the surface. This model, based on field observations implies that the gases which initially escaped up the hydrothermal conduit were

  5. Towards a comprehensive classification of igneous rocks and magmas

    NASA Astrophysics Data System (ADS)

    Middlemost, Eric A. K.

    1991-08-01

    The IUGS Subcommission on the Systematics of Igneous Rocks has recently published an excellent book on the classification of these rocks. This event has shifted the vexed question of classification towards the top of the agenda in igneous petrology. Over the years the Subcommission has used many different criteria to establish the positions of the boundaries between the various common igneous rocks. It now has to adopt a holistic approach and develop a comprehensive, coherent classification that is purged of all the minor anomalies that arise between the various classifications that it has approved. It is appreciated that the Subcommission's classification was never intended to have any genetic implications; however, it is suggested that an ideal classification should he presented in such a way that it is able to group rocks into an order that directs attention to petrogenetic relationships between individual rocks and larger groups of rocks. Unfortunately, many of the Subcommission's definitions are Earth chauvinistic; for example, igneous rocks are defined as being those rocks that solidified from a molten state either within or on the surface of the Earth. Nowhere in the book is it acknowledged that during the past 20 years, while the Subcommission has been framing its many recommendations, a whole new science of planetary petrology has subsumed classical petrology. In any new edition of the book, the Subcommission should acknowledge that rocks are essentially the solid materials of which planets, natural satellites and other broadly similar cosmic bodies are made. The Subcommission should also explicitly recognise that igneous rocks can be divided into either a main sequence of essentially common rocks or a number of supplementary clans of special rocks that evolved outside the main sequence. It is hoped that in the near future the Subcommission will rescind its recommendation that the TAS classification should be regarded as an adjunct to its more traditional

  6. Alkaline Earth Metal and Lanthanide(III) Complexes of Ligands Based upon 1,4,7,10-Tetraazacyclododecane-1,7-bis(acetic acid).

    PubMed

    Huskens, Jurriaan; Torres, Diego A.; Kovacs, Zoltan; André, João P.; Geraldes, Carlos F. G. C.; Sherry, A. Dean

    1997-03-26

    The macrocyclic ligand DO2A (1,4,7,10-tetraazacyclododecane-1,7-bis(acetic acid)) was prepared and used as a building block for four new macrocyclic ligands having mixed side-chain chelating groups. These ligands and their complexes with Mg(II), Ca(II), and Ln(III) were studied extensively by potentiometry, high-resolution NMR, and water proton relaxivity measurements. The protonation constants of all compounds compared well with those of other cyclen-based macrocyclic ligands. All Ca(II) complexes were found to be more stable than the corresponding Mg(II) complexes. Trends for the stabilities of the Ln(III) complexes are discussed and compared with literature data, incorporating the effects of water coordination numbers, Ln(III) contraction, and the nature of the side chains and the steric hindrance between them. (1)H NMR titrations of DO2A revealed that the first and second protonations take place preferentially at the secondary ring nitrogens, while the third and fourth involved protonation of the acetates. (17)O NMR shifts showed that the DyDO2A(+) complex had two inner-sphere water molecules. Water proton spin-lattice relaxation rates for the GdDO2A(+) complex were also consistent with water exchange between bulk water and two inner-sphere Gd(III) coordination positions. Upon formation of the diamagnetic complexes of DO2A (Ca(II), Mg(II), La(III), and Lu(III)), all of the macrocyclic ring protons became nonequivalent due to slow conformational rearrangements, while the signals for the acetate CH(2) protons remained a singlet.

  7. Effects of Compositional and Structural Variations on Log Responses in Igneous and Metamorphic Rocks

    NASA Astrophysics Data System (ADS)

    Pechnig, R.; Bartetzko, A.; Delius, H.

    2001-12-01

    Petrophysical in-situ data of several boreholes drilled igneous and metamorphic rocks of continental and oceanic basement were analyzed in order to characterize and classify the occurring rock types. Since physical properties of crystalline rocks are controlled by both, compositional and structural features, one objective of this study was to develop methods to detect and quantify matrix effects. The comparison of mineralogical and geochemical core data with wireline data reveal following systematic observations: (1) Mafic rocks (e.g. oceanic basalts, volcanic island basalts, gabbros and amphibolites) generally have low contents of radioactive minerals. This is in particular valid for mafic rocks from the upper and lower oceanic crust. Slight increases in gamma-ray are related to an enrichment in potassium due to seafloor alteration. In contrast to this uniform, mantle source controlled rocks, extrusives and re-sedimented material from ocean islands and large igneous provinces show a large scatter in gamma-ray responses as a result of their more complex evolution. Mafic rocks recovered from boreholes into continental crust, are characterized by high gamma-ray values, due to enrichment of thorium and uranium during regional metamorphism. In contrast to the mafic plutonic and metamorphic rocks, where the density and p-wave velocity is controlled by the mineralogical composition, the physical parameters of mafic volcanic rocks are strongly affected by fracturing and vesicularity. Density, p-wave velocity and electrical resistivity logs are significantly lowered depending on the degree of vesicularity and fracturing. (2) Acid to intermediate igneous rocks and orthogneisses are distinguishable from paragneisses by their log responses despite showing a similar geochemical composition. The main difference occurs for the relation of the gamma-ray log to the density and neutron porosity log. The gamma-ray in paragneisses is controlled by the amount of phyllosilicates, which

  8. Primary Igneous Anhydrite: Progress Since the 1982 El Chichón Eruption (Mexico)

    NASA Astrophysics Data System (ADS)

    Luhr, J. F.

    2006-05-01

    Anhydrite (CaSO4) was confirmed as a stable primary igneous mineral, capable of precipitating from a silicate melt, through petrographic observations of fresh trachyandesitic pumices erupted in the spring of 1982 from El Chichón, a little known, isolated tuff and lava-dome complex in eastern Mexico. The 1982 eruption was also notable for the associated release of an estimated 5-9 megatons of SO2 to the stratosphere and troposphere, as measured by the Total Ozone Mapping Spectrometer. Subsequent years saw confirmation of primary igneous anhydrite in laboratory phase-equilibrium experiments, and anhydrite was also observed in the products of several subsequent explosive eruptions, most importantly dacitic pumices from the massive 15 June 1991 eruption of Mount Pinatubo, in the Philippines. That eruption involved ~5X the mass of magma and ~3X the mass of SO2 release compared to El Chichón's eruption. For both the Pinatubo and El Chichón eruptions, it has been concluded that the sulfur released to the atmosphere was too great in mass to have been dissolved in the erupted melt volume just prior to eruption. In both cases workers advocated the existence of a separate gas phase prior to eruption, where much of the subsequently released sulfur was present. Thus, primary igneous anhydrite has been linked with another important phenomenon: excess sulfur release during volcanic eruptions. This presentation will review other developments concerning primary igneous anhydrite since 1982. These include: (1) other examples of primary anhydrite from volcanic samples (Nevado del Ruiz, Colombia; Lascar, Chile; Sutter Buttes, USA; Eagle Mountain, USA; Shiveluch, Russia; (2) examples of primary anhydrite from plutonic samples (Julcani, Peru; Santa Rita, USA; Cajon Pass Scientific Drillhole, USA); (3) laboratory experiments that have expanded our understanding of the T-P-fO2 conditions of anhydrite stability, melt/vapor partition coefficients for sulfur as a function of these

  9. Martian Igneous Geochemistry: The Nature of the Martian Mantle

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Elkins-Tanton, L. T.; Peng, Z. X.; Herrin, J. S.

    2012-01-01

    Mafic igneous rocks probe the interiors of their parent objects, reflecting the compositions and mineralogies of their source regions, and the magmatic processes that engendered them. Incompatible trace element contents of mafic igneous rocks are widely used to constrain the petrologic evolution of planets. We focus on incompatible element ratios of martian meteorites to constrain the petrologic evolution of Mars in the context of magma ocean/cumulate overturn models [1]. Most martian meteorites contain some cumulus grains, but regardless, their incompatible element ratios are close to those of their parent magmas. Martian meteorites form two main petrologic/ age groupings; a 1.3 Ga group composed of clinopyroxenites (nakhlites) and dunites (chassignites), and a <1 Ga group composed of basalts and lherzolites (shergottites).

  10. Igneous Consequence Modeling for the TSPA-SR

    SciTech Connect

    John McCord

    2001-10-29

    The purpose of this technical report is to develop credible, defendable, substantiated models for the consequences of igneous activity for the TSPA-SR Model. The effort will build on the TSPA-VA and improve the quality of scenarios and depth of the technical basis underlying disruptive events modeling. Computational models for both volcanic eruptive releases (this is an event that results in ash containing waste being ejected from Yucca Mountain) and igneous intrusion groundwater releases (this is an event that reaches the repository level, impacts the waste packages, and produces releases from waste packages damaged by igneous activity) will be included directly in the TSPA calculations as part of the TSPA-SR Model. This Analysis Model Report (AMR) is limited to development of the conceptual models for these two scenarios. The mathematical implementation of these conceptual models will be done within the TSPA-SR Model. Thus, this AMR will not include any model results or sensitivity analyses. Calculation of any doses resulting from igneous releases will also be done within the TSPA-SR model, as will the probabilistic weighting of these doses. Calculation and analysis of the TSPA-SR Model results for igneous disruption are, therefore, outside the scope of this activity. The reason for not running the mathematical models as part of this AMR is that the models are integrated within the TSPA-SR model and, thus, any model simulations and the corresponding results are out of the scope of this AMR. The scope of this work as defined in the development plan (CRWMS M&O 2000j) involves using data that has been extracted from existing sources to design and support the TSPA-SR models for the transport of radionuclides following igneous disruption of the repository. The development plan states ''applications of the code in this analysis will be limited to testing of the code and sensitivity analyses during analysis design.'' In contrast to the development plan, the ASHPLUME

  11. Lunar igneous rocks and the nature of the lunar interior

    NASA Technical Reports Server (NTRS)

    Hays, J. F.; Walker, D.

    1974-01-01

    Lunar igneous rocks are interpreted, which can give useful information about mineral assemblages and mineral chemistry as a function of depth in the lunar interior. Terra rocks, though intensely brecciated, reveal, in their chemistry, evidence for a magmatic history. Partial melting of feldspathic lunar crustal material occurred in the interval 4.6 to 3.9 gy. Melting of ilmenite-bearing cumulates at depths near 100 km produced parent magmas for Apollo 11 and 17 titaniferous mare basalts in the interval 3.8 to 3.6 gy. Melting of ilmenite-free olivine pyroxenites at depths greater than 200 km produced low-titanium mare basalts in the interval 3.4 to 3.1 gy. No younger igneous rocks have yet been recognized among the lunar samples and present-day melting seems to be limited to depths greater than 1000 km.

  12. Lunar igneous rocks and the nature of the lunar interior

    NASA Technical Reports Server (NTRS)

    Hays, J. F.; Walker, D.

    1977-01-01

    Lunar igneous rocks, properly interpreted, can give useful information about mineral assemblages and mineral chemistry as a function of depth in the lunar interior. Though intensely brecciated, terra rocks reveal, in their chemistry, evidence for a magmatic history. Partial melting of feldspathic lunar crustal material occurred in the interval 4.6 to 3.9 Gy. Melting of ilmenite-bearing cumulates at depths near 100 km produced parent magmas for Apollo 11 and 17 titaniferous mare basalts in the interval 3.8 to 3.6 Gy. Melting of ilmenite-free olivine pyroxenites (also cumulates?) at depths greater than 200 km produced low-titanium mare basalts in the interval 3.4 to 3.1 Gy. No younger igneous rocks have yet been recognized among the lunar samples and present-day melting seems to be limited to depths greater than 1000 km.

  13. Felsic Igneous Rocks at Gale Crater : a Comparison with Lithic Clasts in NWA 7533

    NASA Astrophysics Data System (ADS)

    Sautter, V.; Wiens, R. C.; Toplis, M. J.; Cousin, A.; Forni, O.; Fabre, C.

    2014-12-01

    Curiosity rover landed at Gale, an early Hesperian age crater formed within Noachian rocks. In Hummocky plain, more than half of the igneous floats rocks are highly alkaline rocks (Stolper et al. doi: 101126/science.12239463, Schmidt et al. doi: 10.1002/2013JE004481) and feldspar-bearing rocks (Sautter et al. doi: 10.1002/2013JE00447). ChemCam observations at sub-millimeter scale show that these samples contain a significant feldspar component, either associated with LCP in gabbroic texture or with augite in effusive rocks defining an alkaline K-feldspar-bearing suite: basanite, trachy-andesite with porphyritic texture and syenitic rock with apahnitic texture. This series likely resulted from differentiation of liquids produced by low degrees of partial melting of primitive mantle. These rocks are float rocks or occurred as clast in conglomerate suggesting a provenance from Gale crater rim. NWA 7533 is the first Noachian breccia sampling the southern hemisphere Martian regolith. It is a polymict breccia with leucocratic clasts including zircon with 4.4 Ga ages Humayun et al., doi :10.1038/nature). The alkali basaltic evolved clasts contain two feldspars (alkali and plagioclase) and modal recombination gives a basaltic trachy-andesite, gabbroic, trachy-andesite and mugearite clast (Agee et al. doi: 10.1126/science. 1228858). Noritic clasts contain andesine, LCP, and Cr-magnetite. The monzonitic/mugearitic-evolved clasts are composed of alkali feldspar, plagioclase, augite, Ti-Magnetite, Cl-apatite and zircon. These clasts would represent products of Martian crust emplaced at 4.5 Ga and re-melted at 4.4 Ga (Humayun et al., doi :10.1038/nature). The leucocratic clasts of the Noachian SNC breccia will be compared with evolved lithology encountered at Gale crater and products of Noachian magmatism will be discussed.

  14. A Comparison of Microbial Communities from Deep Igneous Crust

    NASA Astrophysics Data System (ADS)

    Smith, A. R.; Flores, G. E.; Fisk, M. R.; Colwell, F. S.; Thurber, A. R.; Mason, O. U.; Popa, R.

    2013-12-01

    Recent investigations of life in Earth's crust have revealed common themes in organism function, taxonomy, and diversity. Capacities for hydrogen oxidation, carbon fixation, methanogenesis and methanotrophy, iron and sulfur metabolisms, and hydrocarbon degradation often predominate in deep life communities, and crustal mineralogy has been hypothesized as a driving force for determining deep life community assemblages. Recently, we found that minerals characteristic of the igneous crust harbored unique communities when incubated in the Juan de Fuca Ridge flank borehole IODP 1301A. Here we present attached mineral biofilm morphologies and a comparison of our mineral communities to those from a variety of locations, contamination states, and igneous crustal or mineralogical types. We found that differences in borehole mineral communities were reflected in biofilm morphologies. Olivine biofilms were thick, carbon-rich films with embedded cells of uniform size and shape and often contained secondary minerals. Encrusted cells, spherical and rod-shaped cells, and tubes were indicative of glass surfaces. We also found that the attached communities from incubated borehole minerals were taxonomically more similar to native, attached communities from marine and continental crust than to communities from the aquifer water that seeded it. Our findings further support the hypothesis that mineralogy selects for microbial communities that have distinct phylogenetic, morphological, and potentially functional, signatures. This has important implications for resolving ecosystem function and microbial distributions in igneous crust, the largest deep habitat on Earth.

  15. 40Ar/39Ar dates from alkaline intrusions of the northern Crazy Mountains, south-central Montana

    NASA Astrophysics Data System (ADS)

    Harlan, S. S.

    2005-05-01

    The Crazy Mountains basin of south-central Montana is a complex foreland basin that formed during the interaction of thin-skinned, decollement-style folds of the Montana thrust belt and the basement-involved folds and thrust faults of the Rocky Mountain foreland province. Near the depositional center of the basin, synorogenic strata of the Paleocene Fort Union Formation have been intruded and locally thermally metamorphosed by strongly alkaline to subalkaline Tertiary intrusive rocks. The subalkaline rocks are found mostly in the southern Crazy Mountains and form stocks (Big Timber stock, Loco Mountain stock), radiating dikes and sills. With the exception of the Ibex Mountain sill (?), the alkaline rocks are restricted to the northern Crazy Mountains. New 40Ar/39Ar dates are reported from the strongly alkaline rocks, including the Comb Creek stock and dike swarm, the Ibex Mountain sill(?), and sills from the Robinson anticline intrusive complex. The alkaline rocks of the Robinson anticline intrusive complex are exposed in the easternmost folds of the Cordilleran fold and thrust belt, but despite their arcuate and apparently folded map geometry they have been shown to post-date folding. Hornblende from a trachyte sill in the Robinson anticline intrusive complex yielded a relatively simple age spectrum with a weighted mean of 50.61 ± 0.14 Ma (2σ), which probably records the age of sill emplacement. Nepheline syenite and mafic nepheline syenites of the Comb Creek stock and a dike from its radial dike swarm, two sills from the Robinson antlicline intrusive complex, and the Ibex Mountains sill(?) gave biotite plateau dates ranging from 50.03 to 50.22 Ma, with 2σ errors of ± 0.11 to 0.19 Ma. Because these dates are from fairly small, hypabyssal intrusions, they must have cooled quickly and thus these dates closely approximate the emplacement age of the intrusions. These data indicate that the strongly alkaline intrusions were emplaced during a fairly restricted

  16. Titanium, zinc and alkaline-earth metal complexes supported by bulky O,N,N,O-multidentate ligands: syntheses, characterisation and activity in cyclic ester polymerisation.

    PubMed

    Sarazin, Yann; Howard, Ruth H; Hughes, David L; Humphrey, Simon M; Bochmann, Manfred

    2006-01-14

    The reactions of the bulky amino-bis(phenol) ligand Me(2)NCH(2)CH(2)N[CH(2)-3,5-Bu(t)(2)-C(6)H(2)OH-2](2)(1-H(2)) with Zn[N(SiMe(3))(2)](2)(4), [Mg[N(SiMe(3))(2)](2)](2)(5) and Ca[N(SiMe(3))(2)](2)(THF)(2)(6) yield the complexes 1-Zn, 1-Mg and 1-Ca in good yields. The X-ray structure of 1-Ca showed the complex to be dimeric, with calcium in a distorted octahedral coordination geometry. Five of the positions are occupied by an N(2)O(3) donor set, while the sixth is taken up by an intramolecular close contact to an o-Bu(t) substituent, a rare case of a Ca...H-C agostic interaction (Ca...H distances of 2.37 and 2.41 Angstroms). Another sterically hindered calcium complex, Ca[2-Bu(t)-6-(C(6)F(5)N=CH)C(6)H(3)O](2)(THF)(2).(C(7)H(8))(2/3)(7), was prepared by reaction of 6 with the iminophenol 2-Bu(t)-6-(C(6)F(5)N=CH)C(6)H(3)OH (3-H). According to the crystal structure 7 is monomeric and octahedral, with trans THF ligands. The complex Ti[N[CH(2)-3-Bu(t)-5-Me-C(6)H(2)O-2](2)[CH(2)CH(2)NMe(2)

  17. Diclofenac salts. III. Alkaline and earth alkaline salts.

    PubMed

    Fini, Adamo; Fazio, Giuseppe; Rosetti, Francesca; Angeles Holgado, M; Iruín, Ana; Alvarez-Fuentes, Josefa

    2005-11-01

    Diclofenac salts containing the alkaline and two earth alkaline cations have been prepared and characterized by scanning electron microscopy (SEM) and EDAX spectroscopy; and by thermal and thermogravimetric analysis (TGA): all of them crystallize as hydrate when precipitated from water. The salts dehydrate at room temperature and more easily on heating, but recovery the hydration, when placed in a humid environment. X-ray diffraction spectra suggest that on dehydration new peaks appear on diffractograms and the lattice of the salts partially looses crystallinity. This phenomenon is readily visible in the case of the calcium and magnesium salts, whose thermograms display a crystallization exotherm, before melting or decomposing at temperatures near or above 200 degrees C; these last salts appear to form solvates, when prepared from methanol. The thermogram of each salt shows a complex endotherm of dehydration about 100 degrees C; the calcium salt displays two endotherms, well separated at about 120 and 160 degrees C, which disappear after prolonged heating. Decomposition exotherms, before or soon after the melting, appear below 300 degrees C. The ammonium salt is thermally unstable and, when heated to start dehydration, dissociates and leaves acidic diclofenac.

  18. Geology and genesis of the Toongi rare metal (Zr, Hf, Nb, Ta, Y and REE) deposit, NSW, Australia, and implications for rare metal mineralization in peralkaline igneous rocks

    NASA Astrophysics Data System (ADS)

    Spandler, Carl; Morris, Caitlin

    2016-12-01

    The Toongi Deposit, located in central NSW, Australia, hosts significant resources of Zr, Hf, Nb, Ta, Y and REE within a small (ca. 0.3 km2), rapidly cooled trachyte laccolith. Toongi is part of regional Late Triassic to Jurassic alkaline magmatic field, but is distinguished from the other igneous bodies by its peralkaline composition and economically significant rare metal content that is homogenously distributed throughout the trachyte body. The primary ore minerals are evenly dispersed throughout the rock and include lueshite/natroniobite and complex Na-Fe-Zr-Nb-Y-REE silicate minerals dominated by a eudialyte group mineral (EGM). The EGM occurs in a unique textural setting in the rock, commonly forming spheroidal or irregular-shaped globules, herein called "snowballs", within the rock matrix. The snowballs are often protruded by aegirine and feldspar phenocrysts and contain swarms of fine aegirine and feldspar grains that often form spiral or swirling patterns within the snowball. Secondary ore minerals include REE carbonates, Y milarite, catapleiite and gaidonnayite that fill fractures and vesicles in the rock. Based on bulk-rock geochemical and Nd isotope data, and thermodynamic modelling of magma fractionation, the alkaline rocks of the region are interpreted to represent extrusive to hyperbyssal products of mantle-derived magma that ponded at mid-crustal levels (ca. 0.3 GPa) and underwent extensive fractionation under low-oxygen fugacity conditions. The high Na2O, peralkaline nature of the Toongi Deposit trachyte developed via extensive fractionation of an alkali olivine basalt parental magma initially in the mid-crust and subsequently at shallow levels (ca. 0.1 GPa). This extended fractionation under low fO2 and relatively low H2O-activity conditions limited volatile release and allowed build-up of rare metal contents to ore grades. We speculate that the ore minerals may have originally formed from rare metal-rich sodic-silicate melt that formed immiscible

  19. Alkaline flooding injection strategy

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1992-03-01

    The objective of this project is to improved alkali-surfactant flooding methods, and this includes determining the proper design of injection strategy. Several different injection strategies have been used or suggested for recovering heavy oils with surfactant-enhanced alkaline flooding methods. Oil recovery was compared for four different injection strategies: (1) surfactant followed by polymer, (2) surfactant followed by alkaline polymer, (3) alkaline surfactant followed by polymer, and (4) alkali, surfactant, and polymer mixed in a single formulation. The effect of alkaline preflush was also studied under two different conditions. All of the oil recovery experiments were conducted under optimal conditions with a viscous, non-acidic oil from Hepler (KS) oil field. The coreflood experiments were conducted with Berea sandstone cores since field core was not available in sufficient quantity for coreflood tests. The Tucker sand of Hepler field is a Class I fluvial dominated deltaic reservoir, as classified by the Department of Energy, which has been selected as the site of a DOE-sponsored field pilot test.

  20. Applications of Real-Time FTIR Spectroscopy to the Elucidation of Complex Electroorganic Pathways: Electrooxidation of Ethylene Glycol on Platinum, Gold, and Nickel in Alkaline Solution

    DTIC Science & Technology

    1991-10-01

    carboxylates along with carbonate. Two other vicinal diol compounds, 2,3-butanediol and 1,2- propanediol , were also studied on nickel in order to ascertain the...indicating that bond scission occurs only at the central, diol, position. As expected on this basis, 1,2- propanediol [CH 3(CHOH)CH20H] yields equal amounts...be present on adjacent carbons, i.e., a vicinal diol. For example, electrooxidation of 1,3- propanediol yields a complex SPAIR spectrum not consistent

  1. Contrasting methods of fracture trend characterization in crystalline metamorphic and igneous rocks of the Windham quadrangle, New Hampshire

    USGS Publications Warehouse

    Walsh, G.J.; Clark, S.F.

    2000-01-01

    The bedrock of the Windham quadrangle in southeastern New Hampshire consists of deformed early Palaeozoic crystalline metamorphic and intrusive igneous rocks intruded by Mesozoic igneous dikes. Generally, less common northeast striking, steeply dipping fractures developed sub-parallel to the pre-existing tectonic foliation in the Palaeozoic rocks. Mesozoic lamprophyre and diabase dikes intruded along the northeast trending fractures, utilizing the pre-existing anisotropy in the crystalline rocks. Northwest striking, steeply dipping systematic joints and joint sets are the most prominent fractures in the area and, at least in part, post-date the Mesozoic dikes. Sub-horizontal sheeting joints occur in all rock types. Locally, the coincidence of the sub-horizontal fractures with a sub-horizontal Paleozoic cleavage suggests that some of the sheeting fractures utilized the pre-existing ductile anisotropy during unloading. Generally, the metasedimentary rocks show a less complex pattern of fracturing than the intrusive rocks suggesting that rock type is a controlling factor. Metasedimentary rocks in the biotite zone and well-foliated igneous rocks show a greater tendency to fracture along pre-existing bedding and foliation surfaces than metasedimentary rocks in the garnet zone and poorly foliated igneous rocks. A comparison of mapped fracture data and station fracture data indicates that either mapped data or station data can be used to identify regional fracture trends. Local fracture trends can not be identified by limited measurements at a few fracture stations, however, because they do not address spatial variability. Some fracture trends may be scale-dependant because they may be either unique to a local area or present only at regional scales.

  2. Application of Sr and O isotope relations to the petrogenesis of the alkaline rocks of the Red Hill complex, New Hampshire, USA

    USGS Publications Warehouse

    Foland, K.A.; Friedman, I.

    1977-01-01

    The Red Hill ring complex in central New Hampshire is composed of apparently cogenetic syenites, nepheline-sodalite syenite, and granite. The ages and petrogenetic relations among five of the six recognized units have been investigated by rubidiumstrontium and oxygen isotope analysis of whole rocks and separated minerals. Whole-rock samples from three syenite units are consistent with a single Rb-Sr isochron which gives an age of 198??3 m.y. and an initial (87Sr/86Sr)o ratio of 0.70330??0.00016 (??2 sigma; ??=1.42?? 10-11y-1). However, Sr isotope data for two other units, nepheline syenite and granite, are not consistent with this isochron but rather indicate higher initial ratios which range from 0.7033 to about 0.707. Whole-rock O isotope analyses give ??18O values which range from+6.2 to+9.3??? Sr and O isotope analyses on mineral separates indicate that observed whole-rock variations in (87Sr/86Sr)o are primary and are not due to any secondary process. The fact that the isotope systematics correlate with rock type, suggests that crustal interaction is likely to have played a significant role in the development of this over-and undersaturated association. Such process(es), while still not fully delineated, could be of fundamental importance to the genesis of associations of critically undersaturated and oversaturated intrusives. The data support the idea that interaction between magmas and crustal materials strongly influenced the compositional relations of similar complexes elsewhere including those of the White Mountain magma series. ?? 1977 Springer-Verlag.

  3. Alkaline earth metal catalysts for asymmetric reactions.

    PubMed

    Kobayashi, Shū; Yamashita, Yasuhiro

    2011-01-18

    The group 2 alkaline earth metals calcium (Ca), strontium (Sr), and barium (Ba) are among the most common elements on Earth, abundant in both the sea and the Earth's crust. Although they are familiar in our daily lives, their application to organic synthesis has, so far, been limited. Some particularly useful properties of these elements include (i) low electronegativity, (ii) a stable oxidation state of +2, meaning that they can potentially form two covalent bonds with anions, and (iii) the ability to occupy a variety of coordination sites due to their large ionic radius. Furthermore, the alkaline earth metals, found between the group 1 and group 3 elements, show mild but significant Lewis acidity, which can be harnessed to control coordinative molecules via a Lewis acid-base interaction. Taken together, these characteristics make the metals Ca, Sr, and Ba very promising components of highly functionalized acid-base catalysts. In this Account, we describe the development of chiral alkaline earth metal catalysts for asymmetric carbon-carbon bond-forming reactions. Recently prepared chiral alkaline earth metal complexes have shown high diastereo- and enantioselectivities in fundamental and important chemical transformations. We chose chiral bisoxazoline (Box) derivatives bearing a methylene tether as a ligand for chiral modification. These molecules are very useful because they can covalently coordinate to alkaline earth metals in a bidentate fashion through deprotonation of the tether portion. It was found that chiral calcium-Box complexes could successfully promote catalytic asymmetric 1,4-addition and [3 + 2] cycloaddition reactions with high diastereo- and enantioselectivities. Both the calcium-Box complexes and chiral strontium-bis-sulfonamide and chiral barium-BINOLate complexes could catalyze asymmetric 1,4-addition reactions with high enantioselectivities. Furthermore, we designed a calcium-neutral coordinative ligand complex as a new type of chiral alkaline

  4. Nonexplosive and explosive magma/wet-sediment interaction during emplacement of Eocene intrusions into Cretaceous to Eocene strata, Trans-Pecos igneous province, West Texas

    USGS Publications Warehouse

    Befus, K.S.; Hanson, R.E.; Miggins, D.P.; Breyer, J.A.; Busbey, A.B.

    2009-01-01

    Eocene intrusion of alkaline basaltic to trachyandesitic magmas into unlithified, Upper Cretaceous (Maastrichtian) to Eocene fluvial strata in part of the Trans-Pecos igneous province in West Texas produced an array of features recording both nonexplosive and explosive magma/wet-sediment interaction. Intrusive complexes with 40Ar/39Ar dates of ~ 47-46??Ma consist of coherent basalt, peperite, and disrupted sediment. Two of the complexes cutting Cretaceous strata contain masses of conglomerate derived from Eocene fluvial deposits that, at the onset of intrusive activity, would have been > 400-500??m above the present level of exposure. These intrusive complexes are inferred to be remnants of diatremes that fed maar volcanoes during an early stage of magmatism in this part of the Trans-Pecos province. Disrupted Cretaceous strata along diatreme margins record collapse of conduit walls during and after subsurface phreatomagmatic explosions. Eocene conglomerate slumped downward from higher levels during vent excavation. Coherent to pillowed basaltic intrusions emplaced at the close of explosive activity formed peperite within the conglomerate, within disrupted Cretaceous strata in the conduit walls, and within inferred remnants of the phreatomagmatic slurry that filled the vents during explosive volcanism. A younger series of intrusions with 40Ar/39Ar dates of ~ 42??Ma underwent nonexplosive interaction with Upper Cretaceous to Paleocene mud and sand. Dikes and sills show fluidal, billowed, quenched margins against the host strata, recording development of surface instabilities between magma and groundwater-rich sediment. Accentuation of billowed margins resulted in propagation of intrusive pillows into the adjacent sediment. More intense disruption and mingling of quenched magma with sediment locally produced fluidal and blocky peperite, but sufficient volumes of pore fluid were not heated rapidly enough to generate phreatomagmatic explosions. This work suggests that

  5. Potential Future Igneous Activity at Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Cline, M.; Perry, F. V.; Valentine, G. A.; Smistad, E.

    2005-12-01

    Location, timing, and volumes of post-Miocene volcanic activity, along with expert judgement, provide the basis for assessing the probability of future volcanism intersecting a proposed repository for nuclear waste at Yucca Mountain, Nevada. Analog studies of eruptive centers in the region that may represent the style and extent of possible future igneous activity at Yucca Mountain have aided in defining the consequence scenarios for intrusion into and eruption through a proposed repository. Modeling of magmatic processes related to magma/proposed repository interactions has been used to assess the potential consequences of a future igneous event through a proposed repository at Yucca Mountain. Results of work to date indicate future igneous activity in the Yucca Mountain region has a very low probability of intersecting the proposed repository. Probability of a future event intersecting a proposed repository at Yucca Mountain is approximately 1.7 X 10-8 per year. Since completion of the Probabilistic Volcanic Hazard Assessment (PVHA) in 1996, anomalies representing potential buried volcanic centers have been identified from aeromagnetic surveys. A re-assessment of the hazard is currently underway to evaluate the probability of intersection in light of new information and to estimate the probability of one or more volcanic conduits located in the proposed repository along a dike that intersects the proposed repository. U.S. Nuclear Regulatory Commission regulations for siting and licensing a proposed repository require that the consequences of a disruptive event (igneous event) with annual probability greater than 1 X 10-8 be evaluated. Two consequence scenarios are considered; 1) igneous intrusion-groundwater transport case and 2) volcanic eruptive case. These scenarios equate to a dike or dike swarm intersecting repository drifts containing waste packages, formation of a conduit leading to a volcanic eruption through the repository that carries the contents of

  6. Potential Future Igneous Activity at Yucca Mountain, Nevada

    SciTech Connect

    M. Cline; F. Perry; G. Valentine; E. Smistad

    2005-05-26

    Location, timing, and volumes of post-Miocene volcanic activity, along with expert judgment, provide the basis for assessing the probability of future volcanism intersecting a proposed repository for nuclear waste at Yucca Mountain, Nevada. Analog studies of eruptive centers in the region that may represent the style and extent of possible future igneous activity at Yucca Mountain have aided in defining the consequence scenarios for intrusion into and eruption through a proposed repository. Modeling of magmatic processes related to magma/proposed repository interactions has been used to assess the potential consequences of a future igneous event through a proposed repository at Yucca Mountain. Results of work to date indicate future igneous activity in the Yucca Mountain region has a very low probability of intersecting the proposed repository. Probability of a future event intersecting a proposed repository at Yucca Mountain is approximately 1.7 x 10{sup -8} per year. Since completion of the Probabilistic Volcanic Hazard Assessment (PVHA) in 1996, anomalies representing potential buried volcanic centers have been identified from aeromagnetic surveys. A re-assessment of the hazard is currently underway to evaluate the probability of intersection in light of new information and to estimate the probability of one or more volcanic conduits located in the proposed repository along a dike that intersects the proposed repository. US Nuclear Regulatory Commission regulations for siting and licensing a proposed repository require that the consequences of a disruptive event (igneous event) with annual probability greater than 1 x 10{sup -8} be evaluated. Two consequence scenarios are considered: (1) igneous intrusion-poundwater transport case and (2) volcanic eruptive case. These scenarios equate to a dike or dike swarm intersecting repository drifts containing waste packages, formation of a conduit leading to a volcanic eruption through the repository that carries the

  7. Igneous Intrusion Impacts on Waste Packages and Waste Forms

    SciTech Connect

    P. Bernot

    2004-08-16

    The purpose of this model report is to assess the potential impacts of igneous intrusion on waste packages and waste forms in the emplacement drifts at the Yucca Mountain Repository. The model is based on conceptual models and includes an assessment of deleterious dynamic, thermal, hydrologic, and chemical impacts. This constitutes the waste package and waste form impacts submodel of the Total System Performance Assessment for the License Application (TSPA-LA) model assessing the impacts of a hypothetical igneous intrusion event on the repository total system performance. This submodel is carried out in accordance with Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of SR and LA (BSC 2003a) and Total System Performance Assessment-License Application Methods and Approaches (BSC 2002a). The technical work plan is governed by the procedures of AP-SIII.10Q, Models. Any deviations from the technical work plan are documented in the TSPA-LA approach to implementing the models for waste package and waste form response during igneous intrusion is based on identification of damage zones. Zone 1 includes all emplacement drifts intruded by the basalt dike, and Zone 2 includes all other emplacement drifts in the repository that are not in Zone 1. This model report will document the following model: (1) Impacts of magma intrusion on the components of engineered barrier system (e.g., drip shields and cladding) of emplacement drifts in Zone 1, and the fate of waste forms. (2) Impacts of conducting magma heat and diffusing magma gases on the drip shields, waste packages, and cladding in the Zone 2 emplacement drifts adjacent to the intruded drifts. (3) Impacts of intrusion on Zone 1 in-drift thermal and geochemical environments, including seepage hydrochemistry. The scope of this model only includes impacts to the components stated above, and does not include impacts to other engineered barrier system (EBS) components such as the invert and

  8. Distinct Igneous APXS Rock Compositions on Mars from Pathfinder, MER and MSL

    NASA Technical Reports Server (NTRS)

    Gellert, Ralf; Arvidson, Raymond; Clark, Benton, III; Ming, Douglas W.; Morris, Richard V.; Squyres, Steven W.; Yen, Albert S.

    2015-01-01

    The alpha particle x-ray spectrometer (APXS) on all four Mars Rovers returned geochemical data from about 1000 rocks and soils along the combined traverses of over 50 kilometers. Here we discuss rocks likely of igneous origin, which might represent source materials for the soils and sediments identified along the traverses. Adirondack-type basalts, abundant in the plains of Gusev Crater, are primitive, olivine bearing basalts. They resemble in composition the basaltic soils encountered at all landing sites, except the ubiquitous elevated S, Cl and Zn in soils. They have been postulated to represent closely the average Martian crust composition. The recently identified new Martian meteorite Black Beauty has similar overall geochemical composition, very distinct from the earlier established SNC meteorites. The rim of the Noachian crater Endeavour, predating the sulfate-bearing Burns formation at Meridiani Planum, also resembles closely the composition of Adirondack basalts. At Gale Crater, the MSL Curiosity rover identified a felsic rock type exemplified by the mugearitic float rock JakeM, which is widespread along the traverse at Gale. While a surprise at that time, possibly related more evolved, alkaline rocks had been previously identified on Mars. Spirit encountered the Wishstone rocks in the Columbia Hills with approx. 6% Na2O+K2O, 15 % Al2O3 and low 12% FeO. Pathfinder rocks with elevated K and Na and >50% SiO2 were postulated to be andesitic. Recently Opportunity encountered the rock JeanBaptisteCharbonneau with >15% Al2O3, >50% SiO2 and approx. 10% FeO. A common characteristic all these rocks is the very low abundance of Cr, Ni and Zn, and an Fe/Mn ratio of about 50, indicating an unaltered Fe mineralogy. Beside these likely igneous rock types, which occurred always in several rocks, a few unique rocks were encountered, e.g. Bounce Rock, a pyroxene-bearing ejecta rock fragment resembling the Shergottite EETA 79001B meteorite. The APXS data can be used to

  9. The Central-Western Mediterranean: Anomalous igneous activity in an anomalous collisional tectonic setting

    NASA Astrophysics Data System (ADS)

    Lustrino, Michele; Duggen, Svend; Rosenberg, Claudio L.

    2011-01-01

    The central-western Mediterranean area is a key region for understanding the complex interaction between igneous activity and tectonics. In this review, the specific geochemical character of several 'subduction-related' Cenozoic igneous provinces are described with a view to identifying the processes responsible for the modifications of their sources. Different petrogenetic models are reviewed in the light of competing geological and geodynamic scenarios proposed in the literature. Plutonic rocks occur almost exclusively in the Eocene-Oligocene Periadriatic Province of the Alps while relatively minor plutonic bodies (mostly Miocene in age) crop out in N Morocco, S Spain and N Algeria. Igneous activity is otherwise confined to lava flows and dykes accompanied by relatively greater volumes of pyroclastic (often ignimbritic) products. Overall, the igneous activity spanned a wide temporal range, from middle Eocene (such as the Periadriatic Province) to the present (as in the Neapolitan of southern Italy). The magmatic products are mostly SiO 2-oversaturated, showing calcalkaline to high-K calcalcaline affinity, except in some areas (as in peninsular Italy) where potassic to ultrapotassic compositions prevail. The ultrapotassic magmas (which include leucitites to leucite-phonolites) are dominantly SiO 2-undersaturated, although rare, SiO 2-saturated (i.e., leucite-free lamproites) appear over much of this region, examples being in the Betics (southeast Spain), the northwest Alps, northeast Corsica (France), Tuscany (northwest Italy), southeast Tyrrhenian Sea (Cornacya Seamount) and possibly in the Tell region (northeast Algeria). Excepted for the Alpine case, subduction-related igneous activity is strictly linked to the formation of the Mediterranean Sea. This Sea, at least in its central and western sectors, is made up of several young (< 30 Ma) V-shaped back-arc basins plus several dispersed continental fragments, originally in crustal continuity with the European

  10. Igneous rocks of the West Sakhalin Terrane of Sakhalin Island

    NASA Astrophysics Data System (ADS)

    Grannik, V. M.

    2016-10-01

    It has been determined that the Rozhdestvenka Formation of the West Sakhalin Terrane composed of Late Mesozoic igneous rocks is a fragment of the accretionary prism of the Rebun-Kabato-Moneron-Samarga island-arc system. Volcanic eruptions, as well as destruction of the Rebun-Kabato-Moneron-Samarga island-arc and the East Sikhote-Alin volcano plutonic marginal continental belt, were the sources of pyroclastic and clastic material entering the sedimentary basin, where the Pobedinsk and Krasnoyarka suites of the West Sakhalin Terrane were formed.

  11. Magnetic fabric constraints of the emplacement of igneous intrusions

    NASA Astrophysics Data System (ADS)

    Maes, Stephanie M.

    Fabric analysis is critical to evaluating the history, kinematics, and dynamics of geological deformation. This is particularly true of igneous intrusions, where the development of fabric is used to constrain magmatic flow and emplacement mechanisms. Fabric analysis was applied to three mafic intrusions, with different tectonic and petrogenetic histories, to study emplacement and magma flow: the Insizwa sill (Mesozoic Karoo Large Igneous Province, South Africa), Sonju Lake intrusion (Proterozoic Midcontinent Rift, Minnesota, USA), and Palisades sill (Mesozoic rift basin, New Jersey, USA). Multiple fabric analysis techniques were used to define the fabric in each intrusive body. Using digital image analysis techniques on multiple thin sections, the three-dimensional shape-preferred orientation (SPO) of populations of mineral phases were calculated. Low-field anisotropy of magnetic susceptibility (AMS) measurements were used as a proxy for the mineral fabric of the ferromagnetic phases (e.g., magnetite). In addition, a new technique---high-field AMS---was used to isolate the paramagnetic component of the fabric (e.g., silicate fabric). Each fabric analysis technique was then compared to observable field fabrics as a framework for interpretation. In the Insizwa sill, magnetic properties were used to corroborate vertical petrologic zonation and distinguish sub-units within lithologically defined units. Abrupt variation in magnetic properties provides evidence supporting the formation of the Insizwa sill by separate magma intrusions. Low-field AMS fabrics in the Sonju Lake intrusion exhibit consistent SW-plunging lineations and SW-dipping foliations. These fabric orientations provide evidence that the cumulate layers in the intrusion were deposited in a dynamic environment, and indicate magma flowed from southwest to northeast, parallel to the pre-existing rift structures. In the Palisades sill, the magnetite SPO and low-field AMS lineation have developed orthogonal to

  12. Magnetostriction and palæomagnetism of igneous rocks

    USGS Publications Warehouse

    Graham, John W.; Buddington, A.F.; Balsley, James R.

    1959-01-01

    IN a recent communication, Stott and Stacey1 report on a “crucial experiment” from which they conclude: “This excellent agreement between the dip and the directions of artificial thermoremanent magnetization of the stressed and unstressed rocks indicates that large systematic errors due to magnetostriction are most improbable in igneous rocks of types normally used for palæomagnetic work”. This experiment was intended to test the proposals2 and measurements3 bearing on the role of magnetostriction in rock magnetism. We present here our reasons for believing that the experiment was not crucial and that the conclusion is not justified.

  13. Alkaline quinone flow battery.

    PubMed

    Lin, Kaixiang; Chen, Qing; Gerhardt, Michael R; Tong, Liuchuan; Kim, Sang Bok; Eisenach, Louise; Valle, Alvaro W; Hardee, David; Gordon, Roy G; Aziz, Michael J; Marshak, Michael P

    2015-09-25

    Storage of photovoltaic and wind electricity in batteries could solve the mismatch problem between the intermittent supply of these renewable resources and variable demand. Flow batteries permit more economical long-duration discharge than solid-electrode batteries by using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based on redox-active organic molecules that are composed entirely of Earth-abundant elements and are nontoxic, nonflammable, and safe for use in residential and commercial environments. The battery operates efficiently with high power density near room temperature. These results demonstrate the stability and performance of redox-active organic molecules in alkaline flow batteries, potentially enabling cost-effective stationary storage of renewable energy.

  14. Advanced alkaline water electrolysis

    NASA Astrophysics Data System (ADS)

    Wakabayashi, N.; Torikai, E.; Kawami, Y.; Takenaka, H.

    Results are presented of experimental studies of possible separators and electrodes for use in advanced, high-temperature, high-pressure alkaline water electrolyzers. Material evaluations in alkaline water electrolyzers at temperatures from 100 to 120 C have shown a new type polytetrafluoroethylene membrane impregnated with potassium titanate to be the most promising when the separator is prepared by the hydrothermal treatment of a porous PFTE membrane impregnated with hydrated titanium oxide. Measurements of cell voltages in 30% KOH at current densities from 5 to 100 A/sq dm at temperatures up to 120 C with nickel electrodes of various structures have shown the foamed nickel electrode, with an average pore size of 1-1.5 mm, to have the best performance. When the foamed nickel is coated by fine powdered nickel, carbonyl nickel or Raney nickel to increase electrode surface areas, even lower cell voltages were found, indicating better performance.

  15. Inclusion of the insecticide fenitrothion in dimethylated-β-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution

    PubMed Central

    Cruickshank, Dyanne L; Rougier, Natalia M; Vico, Raquel V; Bourne, Susan A

    2013-01-01

    Summary An anhydrous 1:1 crystalline inclusion complex between the organophosphorus insecticide fenitrothion [O,O-dimethyl O-(3-methyl-4-nitrophenyl)phosphorothioate] and the host compound heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) was prepared and its structure elucidated by single-crystal X-ray diffraction. This revealed two independent host molecules in the asymmetric unit. In one of these, the cavity is occupied by two disordered guest components (distinguishable as rotamers with respect to the P–OAr bond) while in the other, three distinct guest components with site-occupancies 0.44, 0.29 and 0.27 appear, the last having a reversed orientation relative to all the other components. Kinetic studies of the alkaline hydrolysis of fenitrothion in the presence of DIMEB showed a remarkable reduction of 84% in the rate of this reaction relative to that for the free substrate, a value exceeding those previously attained with the native hosts, β- and γ-cyclodextrin, and fully methylated β-cyclodextrin. PMID:23400042

  16. Late Paleozoic vertical crustal growth of Western Junggar, Xinjiang in China: evidence from petrology and Nd isotope in charnockites and alkaline granites

    NASA Astrophysics Data System (ADS)

    Xian, W. S.; Sun, M.; Zhang, L. F.; Zhao, G. C.; Malpas, J.

    2003-04-01

    This abstract reports our new petrographic, mineralogical, geochemical and Nd isotope studies on the charnockites and alkaline granites in the western Junggar of Xinjiang, China. During the 1997 field excursion, we for the first time discovered charnockites in the Miaergou alkaline granite batholith, one of the six largest intrusive A-type bodies in the western Junggar of Xinjiang, Northwest China. The batholith is located in the southwestern part of the East-Central Asian Orogenic Belt, which is characterized by the presence of voluminous Paleozoic to Mesozoic granitoids with positive ɛNd(t) values. In spatial distribution, the batholith occurs as a ring-like igneous complex, which intrudes the early-Carboniferous volcanic sedimentary rocks of low-grade metamorphism. It is mainly composed of charnockite, quartz diorite, alkaline granite, potash feldspar granite, syenite and rare tourmaline-bearing intermediate-mafic dykes. Charnockites occur only within the diorite. A large amount of gabbroic, dioritic and leucogranitic enclaves are found in a zone between the alkaline granite and diorite. Petrographic and mineralogical studies indicate that the charnockites were derived from partial melting of the lower crust and crystallized under P-T conditions of 5.44˜5.63 ± 1.0 kbar and 700˜800^oC. Zircons from a charnockite sample and an alkaline granite sample yielded concordant U-Pb TIMS ages of 305.3 ± 1. 1 Ma and 274.1 ± 2.9 Ma, respectively, interpreted as the age of the emplacement of the charnockites and alkaline granites. Two-pyroxene granulites, biotite-spinel-cordierite gneisses and sillimanlite-biotite gneisses occur as enclaves within the charnockites. The two-pyroxene granulite enclaves are considered to be restites of partial melting of the previous lower crust at ˜845^oC, whereas the xenoliths of biotite-spinel-cordierite and sillimanlite-biotite gneisses were metamorphosed at low-pressure amphibolite- to granulite-facies, which were related to the

  17. The role of igneous sills in shaping the Martian uplands

    NASA Technical Reports Server (NTRS)

    Wilhelms, D. E.; Baldwin, R. J.

    1989-01-01

    Relations among geologic units and landforms suggest that igneous sills lie beneath much of the intercrater and intracrater terrain of the Martian uplands. The igneous rocks crop out along the upland-lowland front and in crater floors and other depressions that are low enough to intersect the sill's intrusion horizons. It is suggested that heat from the cooling sills melted some of the ice contained in overlying fragmental deposits, creating valley networks by subsurface flow of the meltwater. Terrains with undulatory, smooth surfaces and softened traces of valleys were created by more direct contact with the sills. Widespread subsidence following emplacement of the sills deformed both them and the nonvolcanic deposits that overlie them, accounting for the many structures that continue from ridged plains into the hilly uplands. Crater counts show that the deposit that became valleyed, softened, and ridged probably began to form (and to acquire interstitial ice) during or shortly after the Middle Noachian Epoch, and continued to form as late as the Early Hesperian Epoch. The upper layers of this deposit, many of the visible valleys, and the ridged plains and postulated sills all have similar Early Hesperian ages. Continued formation of valleys is indicated by their incision of fresh-appearing crater ejecta. The dependence of valley formation on internal processes implies that Mars did not necessarily have a dense early atmosphere or warm climate.

  18. Post-igneous redistribution of components in eucrites

    NASA Technical Reports Server (NTRS)

    Phinney, W. C.; Lindstrom, D. J.; Mittlefehldt, D. W.; Martinez, R. R.

    1993-01-01

    In our analyses, we utilize a microdrilling technique that removes 40 to 100 micron diameter cores from mineral grains in thin sections analyzed by microprobe. The cores are then analyzed by INAA using the technique of Lindstrom. Three eucrites were selected for application of this analytical technique: monomict breccias Pasamonte and Stannern and unbrecciated EET90020. Pasamonte is among the most unequilibrated of the eucrites on the basis of zoning in pyroxenes and is considered to be an igneous rock not significantly affected by metamorphism. Stannern has igneous texture but its pyroxenes indicate some re-equilibration, although little, if any, recrystallization. EET90020 has a granulite texture and has been substantially recrystallized. Our sample of Pasamonte contains several clasts of different grain sizes ranging from glass to fine grained with diabasic texture containing lathy plagioclase, unexsolved pigeonite, and mesostasis. Cores were taken of the glass and from minerals and mesostases in six lithic clasts which normally allowed sampling of more than one phase per clast. Our sample of Stannern is also a breccia but with little difference in grain size between clasts and matrix. The plagioclase and pigeonite are blocky, twinned, and exsolved and coexist with a bit of mesostasis. Cores were taken of plagioclase and pigeonite with no attempt to distinguish separate clasts. EET90020 is a granular mixture of twinned plagioclase and pigeonite having rather uniform size and many triple junctions. Several cores were taken of both phases. Both clear and cloudy grains of plagioclase and pyroxene were sampled in all three eucrites.

  19. The alkaline earth intercalates of molybdenum disulfide

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Hadek, V.; Rembaum, A.; Samson, S.; Woollam, J. A.

    1975-01-01

    Molybdenum disulfide has been intercalated with calcium and strontium by means of the liquid ammonia technique. Chemical, X-ray, and superconductivity data are presented. The X-ray data reveal a lowering of crystal symmetry and increase of complexity of the structure upon intercalation with the alkaline earth metals. The Ca and Sr intercalates start to superconduct at 4 and 5.6 K, respectively, and show considerable anisotropy regarding the critical magnetic field.

  20. Mafic and felsic igneous rocks at Gale crater

    NASA Astrophysics Data System (ADS)

    Sautter, Violaine; Cousin, Agnès; Mangold, Nicolas; Toplis, Michael; Fabre, Cécile; Forni, Olivier; Payré, Valérie; Gasnault, Olivier; Ollila, Anne; Rapin, William; Fisk, Martin; Meslin, Pierre-Yves; Wiens, Roger; Maurice, Sylvestre; Lasue, Jérémie; Newsom, Horton; Lanza, Nina

    2015-04-01

    The Curiosity rover landed at Gale, an early Hesperian age crater formed within Noachian terrains on Mars. The rover encountered a great variety of igneous rocks to the west of the Yellow Knife Bay sedimentary unit (from sol 13 to 800) which are float rocks or clasts in conglomerates. Textural and compositional analyses using MastCam and ChemCam Remote micro Imager (RMI) and Laser Induced Breakdown Spectroscopy (LIBS) with a ˜300-500 µm laser spot lead to the recognition of 53 massive (non layered) igneous targets, both intrusive and effusive, ranging from mafic rocks where feldspars form less than 50% of the rock to felsic samples where feldspar is the dominant mineral. From morphology, color, grain size, patina and chemistry, at least 5 different groups of rocks have been identified: (1) a basaltic class with shiny aspect, conchoidal frature, no visible grains (less than 0.2mm) in a dark matrix with a few mm sized light-toned crystals (21 targets) (2) a porphyritic trachyandesite class with light-toned, bladed and polygonal crystals 1-20 mm in length set in a dark gray mesostasis (11 targets); (3) light toned trachytes with no visible grains sometimes vesiculated or forming flat targets (6 targets); (4) microgabbro-norite (grain size < 1mm) and gabbro-norite (grain size >1 mm) showing dark and light toned crystals in similar proportion ( 8 targets); (5) light-toned diorite/granodiorite showing coarse granular (>4 mm) texture either pristine or blocky, strongly weathered rocks (9 rock targets). Overall, these rocks comprise 2 distinct geochemical series: (i) an alkali-suite: basanite, gabbro trachy-andesite and trachyte) including porphyritic and aphyric members; (ii) quartz-normative intrusives close to granodioritic composition. The former looks like felsic clasts recently described in two SNC meteorites (NWA 7034 and 7533), the first Noachian breccia sampling the martian regolith. It is geochemically consistent with differentiation of liquids produced by low

  1. Rb-Sr age of lunar igneous rocks 62295 and 14310

    NASA Technical Reports Server (NTRS)

    Mark, R. K.; Lee-Hu, C.-N.; Wetherill, G. W.

    1974-01-01

    Measurements of Rb-Sr ages of crystallization performed on igneous lunar highland rocks 62295 and 14310 are reported. Lunar sample 62295 is a mesostasis-rich spinel-troctolite very-high-alumina basalt exhibiting a variable igneous structure. Sample 14310 is a feldspathic KREEP-rich basalt. The determined ages probably date the cooling of shock melts.

  2. The "Key" Method of Identifying Igneous and Metamorphic Rocks in Introductory Laboratory.

    ERIC Educational Resources Information Center

    Eves, Robert Leo; Davis, Larry Eugene

    1987-01-01

    Proposes that identification keys provide an orderly strategy for the identification of igneous and metamorphic rocks in an introductory geology course. Explains the format employed in the system and includes the actual key guides for both igneous and metamorphic rocks. (ML)

  3. U-Th-Pb geochronology of meta-carbonatites and meta-alkaline rocks in the southern Canadian Cordillera: A geodynamic perspective

    NASA Astrophysics Data System (ADS)

    Millonig, Leo J.; Gerdes, Axel; Groat, Lee A.

    2012-11-01

    U-Pb and Th-Pb ages of zircons from seven meta-carbonatite and three meta-alkaline rock samples provide evidence for three distinct episodes of carbonatite and alkaline magmatism in the southern Canadian Cordillera spanning a period of ~ 460 Ma. The earliest, Neoproterozoic event occurred at ~ 800-700 Ma and coincides with the postulated initial break-up of Rodinia. The second, previously undocumented, event of carbonatitic magmatism is constrained to the Late Cambrian at ~ 500 Ma and corresponds to a period of extensional tectonics that affected the western continental margin of North America from the Canadian Cordillera to the southwestern United States. The youngest and most prevalent period of alkaline igneous activity occurred in Late Devonian to Early Carboniferous times at ~ 360-340 Ma and resulted from extensional tectonics, presumably caused by slab rollback. In addition, different episodes of amphibolite-facies metamorphism subsequently affected the igneous rocks between ~ 155 and 50 Ma. This dataset puts new constraints on the timing of carbonatite and alkaline igneous activity and the evolution of (ancestral) North America's western continental margin from Neoproterozoic to Carboniferous times.

  4. Presentation and interpretation of chemical data for igneous rocks

    USGS Publications Warehouse

    Wright, T.L.

    1974-01-01

    Arguments are made in favor of using variation diagrams to plot analyses of igneous rocks and their derivatives and modeling differentiation processes by least-squares mixing procedures. These methods permit study of magmatic differentiation and related processes in terms of all of the chemical data available. Data are presented as they are reported by the chemist and specific processes may be modeled and either quantitatively described or rejected as inappropriate or too simple. Examples are given of the differing interpretations that can arise when data are plotted on an AEM ternary vs. the same data on a full set of MgO variation diagrams. Mixing procedures are illustrated with reference to basaltic lavas from the Columbia Plateau. ?? 1974 Springer-Verlag.

  5. Evolution of the martian mantle as recorded by igneous rocks

    NASA Astrophysics Data System (ADS)

    Balta, J. B.; McSween, H. Y.

    2013-12-01

    Martian igneous rocks provide our best window into the current state of the martian mantle and its evolution after accretion and differentiation. Currently, those rocks have been examined in situ by rovers, characterized in general from orbiting spacecraft, and analyzed in terrestrial laboratories when found as meteorites. However, these data have the potential to bias our understanding of martian magmatism, as most of the available meteorites and rover-analyzed rocks come from the Amazonian (<2 Ga) and Hesperian (~3.65 Ga) periods respectively, while igneous rocks from the Noachian (>3.8 Ga) have only been examined by orbiters and as the unique meteorite ALH 84001. After initial differentiation, the main planetary-scale changes in the structure of Mars which impact igneous compositions are cooling of the planet and thickening of the crust with time. As the shergottite meteorites give ages <500 Ma1, they might be expected to represent thick-crust, recent volcanism. Using spacecraft measurements of volcanic compositions and whole rock compositions of meteorites, we demonstrate that the shergottite meteorites do not match the composition of the igneous rocks composing the young volcanoes on Mars, particularly in their silica content, and no crystallization or crustal contamination trend reproduces the volcanoes from a shergottite-like parent magma. However, we show that the shergottite magmas do resemble older martian rocks in composition and mineralogy. The Noachian-aged meteorite ALH 84001 has similar radiogenic-element signatures to the shergottites and may derive from a similar mantle source despite the age difference2. Thus, shergottite-like magmas may represent melting of mantle sources that were much more abundant early in martian history. We propose that the shergottites represent the melting products of an originally-hydrous martian mantle, containing at least several hundred ppm H2O. Dissolved water can increase the silica content of magmas and thus

  6. Primary igneous rocks on Mars: Composition and distribution

    NASA Technical Reports Server (NTRS)

    Singer, Robert B.; Mcsween, Harry Y., Jr.

    1991-01-01

    The present knowledge of the crustal composition of Mars is synthesized and implications discussed for in-situ resource utilization. Sources of information include remote sensing observations, Viking XRF chemical measurements, and characteristics of the SNC meteorites (which most researchers now believe originated on Mars). There are a number of lines of evidence that abundant ferrous-iron rich igneous crustal rocks (and derivative soils) are available at or very near the current Martian surface at many locations on the planet. Most of these exposures show spectroscopic evidence for abundant pyroxene, consistent with basaltic compositions. The SNC meteorites, which have basaltic compositions, were also studied extensively. Interpretations of Mars crustal chemistry and mineralogy (petrology) based on these various sources are reviewed, and their consistencies and differences are discussed.

  7. Major and trace elements in igneous rocks from Apollo 15.

    NASA Technical Reports Server (NTRS)

    Helmke, P. A.; Blanchard, D. P.; Haskin, L. A.; Telander, K.; Weiss, C.; Jacobs, J. W.

    1973-01-01

    The concentrations of major and trace elements have been determined in igneous rocks from Apollo 15. All materials analyzed have typical depletions of Eu except for minerals separated from sample 15085. Four samples have concentrations of trace elements that are similar to those of KREEP. The samples of mare basalt from Apollo 15 have higher concentrations of FeO, MgO, Mn, and Cr and lower concentrations of CaO, Na2O, K2O, and rare-earth elements (REE) as compared to the samples of mare basalt from Apollos 11, 12, and 14. The samples can be divided into two groups on the basis of their normative compositions. One group is quartz normative and has low concentrations of FeO while the other is olivine normative and has high concentrations of FeO. The trace element data indicate that the samples of olivine normative basalt could be from different portions of a single lava flow.

  8. The Search for Igneous Materials at the Viking Landing Sites

    NASA Technical Reports Server (NTRS)

    Arvidson, R. E.; Dale-Bannister, M.; Guinnes, E. A.

    1985-01-01

    The use of Viking Lander 6 channel (0.4 to 1.1 microns) images to identify igneous materials is discussed. Movies of synthetic image cubes demonstrate that there are a number of contrast reversals between soils and certain rocks. Typically, large, angular rocks are brighter than the surrounding soils in the shortest wavelengths, and much darker than the soils at longest wavelengths. These results, which seem difficult to explain solely on the basis of photometric effects related to local lighting and viewing, are consistent with the presence of Fe+2 bearing silicates at the rock surfaces, producing relatively moderate absorptions in the blue and green parts of the spectrum, but more significant absorptions near about 1.0 micrometer (e.g., Fe+2 bearing pyroxenes). The soils, on the other hand, have signatures consistent with strong Fe+3 related absorptions at shorter wavelengths (e.g., Fe+3 bearing oxides or hydroxides).

  9. The High Arctic Large Igneous Province Mantle Plume caused uplift of Arctic Canada

    NASA Astrophysics Data System (ADS)

    Galloway, Jennifer; Ernst, Richard; Hadlari, Thomas

    2016-04-01

    The Sverdrup Basin is an east-west-trending extensional sedimentary basin underlying the northern Canadian Arctic Archipelago. The tectonic history of the basin began with Carboniferous-Early Permian rifting followed by thermal subsidence with minor tectonism. Tectonic activity rejuvenated in the Hauterivian-Aptian by renewed rifting and extension. Strata were deformed by diapiric structures that developed during episodic flow of Carboniferous evaporites during the Mesozoic and the basin contains igneous components associated with the High Arctic Large Igneous Province (HALIP). HALIP was a widespread event emplaced in multiple pulses spanning ca. 180 to 80 Ma, with igneous rocks on Svalbard, Franz Josef Island, New Siberian Islands, and also in the Sverdrup Basin on Ellef Ringnes, Axel Heiberg, and Ellesmere islands. Broadly contemporaneous igneous activity across this broad Arctic region along with a reconstructed giant radiating dyke swarm suggests that HALIP is a manifestation of large mantle plume activity probably centred near the Alpha Ridge. Significant surface uplift associated with the rise of a mantle plume is predicted to start ~10-20 my prior to the generation of flood basalt magmatism and to vary in shape and size subsequently throughout the LIP event (1,2,3) Initial uplift is due to dynamical support associated with the top of the ascending plume reaching a depth of about 1000 km, and with continued ascent the uplift topography broadens. Additional effects (erosion of the ductile lithosphere and thermal expansion caused by longer-term heating of the mechanical lithosphere) also affect the shape of the uplift. Topographic uplift can be between 1 to 4 km depending on various factors and may be followed by subsidence as the plume head decays or become permanent due to magmatic underplating. In the High Arctic, field and geochronological data from HALIP relevant to the timing of uplift, deformation, and volcanism are few. Here we present new evidence

  10. Natural radioactivity and radon exhalation rate in Brazilian igneous rocks.

    PubMed

    Moura, C L; Artur, A C; Bonotto, D M; Guedes, S; Martinelli, C D

    2011-07-01

    This paper reports the natural radioactivity of Brazilian igneous rocks that are used as dimension stones, following the trend of other studies on the evaluation of the risks to the human health caused by the rocks radioactivity as a consequence of their use as cover indoors. Gamma-ray spectrometry has been utilized to determine the (40)K, (226)Ra and (232)Th activity concentrations in 14 rock types collected at different quarries. The following activity concentration range was found: 12.18-251.90 Bq/kg for (226)Ra, 9.55-347.47 Bq/kg for (232)Th and 407.5-1615.0 Bq/kg for (40)K. Such data were used to estimate Ra(eq), H(ex) and I(γ), which were compared with the threshold limit values recommended in literature. They have been exceeded for Ra(eq) and H(ex) in five samples, where the highest indices corresponded to a rock that suffered a process of ductile-brittle deformation that caused it a microbrecciated shape. The exhalation rate of Rn and daughters has also been determined in slabs consisting of rock pieces ~10 cm-long, 5 cm-wide and 3 cm-thick. It ranged from 0.24 to 3.93 Bq/m(2)/h and exhibited significant correlation with eU (=(226)Ra), as expected. The results indicated that most of the studied rocks did not present risk to human health and may be used indoors, even with low ventilation. On the other hand, igneous rocks that yielded indices above the threshold limit values recommended in literature may be used outdoors without any restriction or indoors with ample ventilation.

  11. Geochronology of igneous rocks and formation of the Late Paleozoic south Mongolian active margin of the Siberian continent

    NASA Astrophysics Data System (ADS)

    Yarmolyuk, V. V.; Kovalenko, V. I.; Sal'Nikova, E. B.; Kovach, V. P.; Kozlovsky, A. M.; Kotov, A. B.; Lebedev, V. I.

    2008-04-01

    The succession of magmatic events associated with development of the Early Carboniferous-Early Permian marginal continental magmatic belt of southern Mongolia is studied. In the belt structure there are defined the successive rock complexes: the older one represented by differentiated basalt-andesite-rhyodacite series and younger bimodal complex of basalt-comendite-trachyrhyolite composition. The granodiorite-plagiogranite and banatite (diorite-monzonite-granodiorite) plutonic massifs are associated with the former, while peralkaline granite massifs are characteristic of the latter. First systematic geochronological study of igneous rock associations is performed to establish time succession and structural position of both complexes. Geochronological results and geological relations between rocks of the bimodal and differentiated complexes showed first that rocks of the differentiated complex originated 350 to 330 Ma ago at the initial stage of development of the marginal continental belt. This is evident from geochronological dates obtained for the Adzh-Bogd and Edrengiyn-Nuruu massifs and for volcanic associations of the complex. The dates are consistent with paleontological data. The bimodal association was formed later, 320 to 290 Ma ago. The time span separating formation of two igneous complexes ranges from several to 20 30 m.y. in different areas of the marginal belt. The bimodal magmatism was interrelated with rifting responsible for development of the Gobi-Tien Shan rift zone in the belt axial part and the Main Mongolian lineament along the belt northern boundary. Loci of bimodal rift magmatism likely migrated with time: the respective magmatic activity first initiated on the west of the rift system and then advanced gradually eastward with development of rift structures. Normal granitoids untypical but occurring nevertheless among the products of rift magmatism in addition to peralkaline massifs are assumed to have been formed, when the basic magmatism

  12. Geochemical characteristics of igneous rocks associated with epithermal mineral deposits—A review

    USGS Publications Warehouse

    du Bray, Edward A.

    2017-01-01

    Newly synthesized data indicate that the geochemistry of igneous rocks associated with epithermal mineral deposits varies extensively and continuously from subalkaline basaltic to rhyolitic compositions. Trace element and isotopic data for these rocks are consistent with subduction-related magmatism and suggest that the primary source magmas were generated by partial melting of the mantle-wedge above subducting oceanic slabs. Broad geochemical and petrographic diversity of individual igneous rock units associated with epithermal deposits indicate that the associated magmas evolved by open-system processes. Following migration to shallow crustal reservoirs, these magmas evolved by assimilation, recharge, and partial homogenization; these processes contribute to arc magmatism worldwide.Although epithermal deposits with the largest Au and Ag production are associated with felsic to intermediate composition igneous rocks, demonstrable relationships between magmas having any particular composition and epithermal deposit genesis are completely absent because the composition of igneous rock units associated with epithermal deposits ranges from basalt to rhyolite. Consequently, igneous rock compositions do not constitute effective exploration criteria with respect to identification of terranes prospective for epithermal deposit formation. However, the close spatial and temporal association of igneous rocks and epithermal deposits does suggest a mutual genetic relationship. Igneous systems likely contribute heat and some of the fluids and metals involved in epithermal deposit formation. Accordingly, deposit formation requires optimization of source metal contents, appropriate fluid compositions and characteristics, structural features conducive to hydrothermal fluid flow and confinement, and receptive host rocks, but not magmas with special compositional characteristics.

  13. Origin of modal and rhythmic igneous layering by sedimentation in a convecting magma chamber

    NASA Astrophysics Data System (ADS)

    Sparks, R. Stephen; Huppert, Herbert E.; Koyaguchi, Takehiro; Hallworth, Mark A.

    1993-01-01

    EXPERIMENTAL investigations of convecting, particle-laden fluids show two regimes for convection driven by cooling from above1. In very dilute suspensions, convection will maintain a homogeneous distribution of particles throughout the convecting layer provided that particle fall velocities are small compared with turbulent fluid velocities. Above a critical concentration, convection is unable to keep the particles suspended, so the particles settle, leaving behind a layer of convecting fluid virtually free of particles. Here we apply these results to cooling magma chambers, in which crystallization leads to an increase in suspended crystal content with time. Discrete sedimentation events are predicted each time the concentration exceeds the critical value. For common igneous minerals, critical concentrations are very small (typically 0.002-0.03 wt%) and layers of the order of centimetres to a few metres thick will result. Because minerals of different density and size have different critical concentrations and settling velocities, complex fluctuations in sedimentation rate and mineral proportions can occur in a multi-component melt. This may lead to either regular repetitive cycles or more complex fluctuations. The process is confined to low-viscosity magmas, such as basalts, in which the crystals are able to separate from the active thermal boundary layer during convection.

  14. IGNEOUS INTRUSION IMPACTS ON WASTE PACKAGES AND WASTE FORMS

    SciTech Connect

    P. Bernot

    2004-04-19

    The purpose of this model report is to assess the potential impacts of igneous intrusion on waste packages and waste forms in the emplacement drifts at the Yucca Mountain Repository. The models are based on conceptual models and includes an assessment of deleterious dynamic, thermal, hydrologic, and chemical impacts. The models described in this report constitute the waste package and waste form impacts submodel of the Total System Performance Assessment for the License Application (TSPA-LA) model assessing the impacts of a hypothetical igneous intrusion event on the repository total system performance. This submodel is carried out in accordance with Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of LA (BSC 2004 [DIRS:167796]) and Total System Performance Assessment-License Application Methods and Approaches (BSC 2003 [DIRS: 166296]). The technical work plan was prepared in accordance with AP-2.27Q, Planning for Science Activities. Any deviations from the technical work plan are documented in the following sections as they occur. The TSPA-LA approach to implementing the models for waste package and waste form response during igneous intrusion is based on identification of damage zones. Zone 1 includes all emplacement drifts intruded by the basalt dike, and Zone 2 includes all other emplacement drifts in the repository that are not in Zone 1. This model report will document the following model assessments: (1) Mechanical and thermal impacts of basalt magma intrusion on the invert, waste packages and waste forms of the intersected emplacement drifts of Zone 1. (2) Temperature and pressure trends of basaltic magma intrusion intersecting Zone 1 and their potential effects on waste packages and waste forms in Zone 2 emplacement drifts. (3) Deleterious volatile gases, exsolving from the intruded basalt magma and their potential effects on waste packages of Zone 2 emplacement drifts. (4) Post-intrusive physical

  15. Complete Analytical Data for Samples of Jurassic Igneous Rocks in the Bald Mountain Mining District, Nevada

    USGS Publications Warehouse

    du Bray, Edward A.

    2009-01-01

    This report presents all petrographic, major oxide, and trace element data for a set of 109 samples collected during an investigation of Jurassic igneous rocks in the Bald Mountain mining district, Nevada. Igneous rocks in the district include the Bald Mountain stock, quartz-feldspar porphyry dikes, basaltic andesite dikes, aplite sills, and rare lamprophyre dikes. These rocks, although variably altered near intrusion-related mineral deposits, are fresh in many parts of the district. Igneous rocks in the district are hosted by Paleozoic sedimentary rocks.

  16. Characterize Framework for Igneous Activity at Yucca Mountain, Nevada

    SciTech Connect

    F. Perry; B. Youngs

    2000-11-06

    The purpose of this Analysis/Model (AMR) report is twofold. (1) The first is to present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) consistent with the volcanic and tectonic history of this region and the assessment of this history by experts who participated in the Probabilistic Volcanic Hazard Analysis (PVHA) (CRWMS M&O 1996). Conceptual models presented in the PVHA are summarized and extended in areas in which new information has been presented. Alternative conceptual models are discussed as well as their impact on probability models. The relationship between volcanic source zones defined in the PVHA and structural features of the YMR are described based on discussions in the PVHA and studies presented since the PVHA. (2) The second purpose of the AMR is to present probability calculations based on PVHA outputs. Probability distributions are presented for the length and orientation of volcanic dikes within the repository footprint and for the number of eruptive centers located within the repository footprint (conditional on the dike intersecting the repository). The probability of intersection of a basaltic dike within the repository footprint was calculated in the AMR ''Characterize Framework for Igneous Activity at Yucca Mountain, Nevada'' (CRWMS M&O 2000g) based on the repository footprint known as the Enhanced Design Alternative [EDA II, Design B (CRWMS M&O 1999a; Wilkins and Heath 1999)]. Then, the ''Site Recommendation Design Baseline'' (CRWMS M&O 2000a) initiated a change in the repository design, which is described in the ''Site Recommendation Subsurface Layout'' (CRWMS M&O 2000b). Consequently, the probability of intersection of a basaltic dike within the repository footprint has also been calculated for the current repository footprint, which is called the 70,000 Metric Tons of Uranium (MTU) No-Backfill Layout (CRWMS M&O 2000b). The calculations for both footprints are presented in this AMR. In addition, the

  17. Alkaline battery, separator therefore

    NASA Technical Reports Server (NTRS)

    Schmidt, George F. (Inventor)

    1980-01-01

    An improved battery separator for alkaline battery cells has low resistance to electrolyte ion transfer and high resistance to electrode ion transfer. The separator is formed by applying an improved coating to an electrolyte absorber. The absorber, preferably, is a flexible, fibrous, and porous substrate that is resistant to strong alkali and oxidation. The coating composition includes an admixture of a polymeric binder, a hydrolyzable polymeric ester and inert fillers. The coating composition is substantially free of reactive fillers and plasticizers commonly employed as porosity promoting agents in separator coatings. When the separator is immersed in electrolyte, the polymeric ester of the film coating reacts with the electrolyte forming a salt and an alcohol. The alcohol goes into solution with the electrolyte while the salt imbibes electrolyte into the coating composition. When the salt is formed, it expands the polymeric chains of the binder to provide a film coating substantially permeable to electrolyte ion transfer but relatively impermeable to electrode ion transfer during use.

  18. Petrology of Igneous Clasts in Regolithic Howardite EET 87503

    NASA Technical Reports Server (NTRS)

    Hodges, Z. V.; Mittlefehldt, D. W.

    2017-01-01

    The howardite, eucrite and diogenite (HED) clan of meteorites is widely considered to originate from asteroid 4 Vesta, as a result of a global magma ocean style of differentiation. A global magmatic stage would allow silicate material to be well mixed, destroying any initial heterogeneity that may have been present resulting in the uniformity of eucrite and diogenite delta(exp 17)O, for example. The Fe/Mn ratio of mafic phases in planetary basalts can be diagnostic of different source bodies as this ratio is little-affected by igneous processes, so long as the oxygen and sulphur fugacities are buffered. Here, pyroxene Fe/Mn ratios in mafic clasts in howardite EET 87503 have been determined to further evaluate whether the HED parent asteroid is uniform. Uniformity would suggest that the parent asteroid was subject to homogenization prior to the formation of HED lithologies, likely through an extensive melting phase. Whereas, distinct differences may point towards heterogeneity of the parent body.

  19. Large Igneous Provinces, Sulfur Aerosols, and Initiation of Snowball Earth

    NASA Astrophysics Data System (ADS)

    Macdonald, F. A.; Wordsworth, R. D.

    2015-12-01

    The events that led to the initiation of Snowball Earth remain poorly understood. Proposed scenarios include a methane addiction, a biological innovation that led to an increase in organic carbon burial and anaerobic remineralization, or an increase in global weatherability due to a paleogeography with a preponderance of low latitude continents, and the subareal implacement of large igneous provinces (LIPs) at the equator. The Franklin LIP was emplaced between 730 and 710 Ma and covers an area of over 2.25 Mkm2 with lavas, sills, and dikes extending over much of northern Laurentia from Alaska through northern Canada to Greenland and potentially to Siberia. The most precise geochronological constraints on the Franklin LIP overlap with the onset of the Sturtian Snowball Earth glaciation, which began between 717 and 716 Ma and marked the first glaciation in over 1 billion years. The Franklin LIP is the largest preserved Neoproterozoic LIP and one of the largest in Earth History. Additionally, it was emplaced at equatorial latitudes with associated sills that invaded epicontinental sulfur evaporite basins, potentially maximizing environmental effects. Here we explore the hypothesis that the Sturtian Snowball Earth was initiated in part by an increase in planetary albedo from the conversion of volcanic SO2/H2S emissions to tropospheric and stratospheric sulfate aerosols through a combination of geochemical and modeling studies.

  20. Pristine Igneous Rocks and the Early Differentiation of Planetary Materials

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.

    2005-01-01

    Our studies are highly interdisciplinary, but are focused on the processes and products of early planetary and asteroidal differentiation, especially the genesis of the ancient lunar crust. The compositional diversity that we explore is the residue of process diversity, which has strong relevance for comparative planetology. Most of the accessible lunar crust consists of materials hybridized by impact-mixing. Our lunar research concentrates on the rare pristine (unmixed) samples that reflect the original genetic diversity of the early crust. Among HED basalts (eucrites and clasts in howardites), we distinguish as pristine the small minority that escaped the pervasive thermal metamorphism of the parent asteroid's crust. We have found a correlation between metamorphically pristine HED basalts and the similarly small minority of compositionally evolved "Stannern trend" samples, which are enriched in incompatible elements and titanium compared to main group eucrites, and yet have relatively high mg ratios. Other topics under investigation included: lunar and SNC (martian?) meteorites; igneous meteorites in general; impact breccias, especially metal-rich Apollo samples and polymict eucrites; siderophile compositions of the lunar and martian mantles; and planetary bulk compositions and origins.

  1. The Igneous SPICEs Suite: Old Programs with a New Look

    NASA Astrophysics Data System (ADS)

    Davenport, J. D.

    2013-12-01

    Understanding the chemistry of magma is important for understanding how the planets differentiated into crusts, rocky mantles, and metallic cores. Magma formation and crystallization can be modeled using computer programs. A valuable and useful set of programs was developed by John Longhi (Lamont-Doherty Earth Observatory, Palisades, New York). John Longhi generously shared these programs widely with colleagues, but they were written in Fortran by John for his own use, and not as user-friendly research tools. As a major part of my Masters thesis at the University of Notre Dame, I was using the programs to do numerous calculations of the crystallization of the lunar magma ocean, the deep, global magma layer surrounding the Moon when it formed. It occurred to me that it would make my life easier if the programs were more straightforward, so working with others at Notre Dame and elsewhere, including John Longhi, I converted the programs for use with MATLAB, a powerful mathematical program. The revisions (Simulating Planetary Igneous Crystallization Environments, SPICEs) have a simple graphical interface for ease of input and output, yet use the same rigorous calculations in the original Longhi programs. My goal is to make the programs more widely used for research and education.

  2. Thermal diffusivity of igneous rocks at elevated pressure and temperature

    SciTech Connect

    Durham, W.B.; Mirkovich, V.V.; Heard, H.C.

    1987-10-10

    Thermal diffusivity measurements of seven igneous rocks were made to temperatures of 400 /sup 0/C and pressures of 200 MPa. The measuring method was based on the concept of cylindrical symmetry and periodic heat pulses. The seven rocks measured were Westerly (Rhode Island) granite, Climax Stock (Nevada) quartz monzonite, Pomona (Washington) basalt, Atikokan (Ontario, Canada) granite, Creighton (Ontario, Canada) gabbro, East Bull Lake (Ontario, Canada) gabbro, and Stripa (Sweden) granite. The diffusivity of all the rocks showed a positive linear dependence on inverse temperature and, excluding the East Bull Lake gabbro, showed a linear dependence on quartz content. (Quartz content varied from 0 to 31% by volume.) Diffusivity in all cases rose or remained steady with increasing confining pressure. The pressure effect was strongest at lowest pressures and vanished by levels between 10 and 100 MPa, depending on rock type. The pressure effect (measured as a percentage change in diffusivity) is stronger in the four rocks of granite composition than in the three of basaltic composition. Our results agree well with existing thermal diffusivity measurements at atmospheric pressure.

  3. Workshop on Evolution of Igneous Asteroids: Focus on Vesta and the HED Meteorites. Pt. 1

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W. (Editor); Papike, James J. (Editor)

    1996-01-01

    This volume contains abstracts of papers that have been accepted for presentation at the Workshop on Evolution of Igneous Asteroids: Focus on Vesta and the HED Meteorites, October 16-18, 1996, in Houston, Texas.

  4. Hawai'i and Gale Crater: A Mars Analogue Study of Igneous, Sedimentary, Weathering, and Alteration Trends in Geochemistry

    NASA Technical Reports Server (NTRS)

    Berger, J. A.; Flemming, R. L.; Schmidt, M. E.; Gellert, R.; Morris, R. V.; Ming, D. W.

    2017-01-01

    Sedimentary rocks in Gale Crater on Mars indicate a varied provenance with a range of alteration and weathering [1, 2]. Geochemical trends identified in basaltic and alkalic sedimentary rocks by the Alpha Particle X-ray Spectrometer (APXS) on the Mars rover Curiosity represent a complex interplay of igneous, sedimentary, weathering, and alteration processes. Assessing the relative importance of these processes is challenging with unknown compositions for parent sediment sources and with the constraints provided by Curiosity's instruments. We therefore look to Mars analogues on Earth where higher-resolution analyses and geologic context can constrain interpretations of Gale Crater geochemical observations. We selected Maunakea (AKA Mauna Kea) and Kohala volcanoes, Hawai'i, for an analogue study because they are capped by post-shield transitional basalts and alkalic lavas (hawaiites, mugearites) with compositions similar to Gale Crater [1, 3]. Our aim was to characterize Hawaiian geochemical trends associated with igneous processes, sediment transport, weathering, and alteration. Here, we present initial results and discuss implications for selected trends observed by APXS in Gale Crater.

  5. Vigrishinite, Zn2Ti4 - x Si4O14(OH,H2O,□)8, a new mineral from the Lovozero alkaline complex, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Britvin, S. N.; Zubkova, N. V.; Chukanov, N. V.; Bryzgalov, I. A.; Lykova, I. S.; Belakovskiy, D. I.; Pushcharovsky, D. Yu.

    2013-12-01

    A new mineral vigrishinite, epistolite-group member and first layer titanosilicate with species-defining Zn, was found at Mt. Malyi Punkaruaiv, in the Lovozero alkaline complex, Kola Peninsula, Russia. It occurs in a hydrothermally altered peralkaline pegmatite and is associated with microcline, ussingite, aegirine, analcime, gmelinite-Na, and chabazite-Ca. Vigrishinite forms rectangular or irregularly shaped lamellae up to 0.05 × 2 × 3 cm flattened on [001]. They are typically slightly split and show blocky character. The mineral is translucent to transparent and pale pink, yellowish-pinkish or colorless. The luster is vitreous. The Mohs' hardness is 2.5-3. Vigrishinite is brittle. Cleavage is {001} perfect. D meas = 3.03(2), D calc = 2.97 g/cm3. The mineral is optically biaxial (-), α = 1.755(5), β = 1.82(1), γ = 1.835(8), 2 V meas = 45(10)°, 2 V calc = 50°. IR spectrum is given. The chemical composition (wt %; average of 9 point analyses, H2O is determined by modified Penfield method) is as follows: 0.98 Na2O, 0.30 K2O, 0.56 CaO, 0.05 SrO, 0.44 BaO, 0.36 MgO, 2.09 MnO, 14.39 ZnO, 2.00 Fe2O3, 0.36 Al2O3, 32.29 SiO2, 29.14 TiO2, 2.08 ZrO2, 7.34 Nb2O5, 0.46 F, 9.1 H2O, -0.19 O=F2, total is 101.75. The empirical formula calculated on the basis of Si + Al = 4 is: H7.42(Zn1.30Na0.23Mn0.22Ca0.07Mg0.07K0.05Ba0.02)Σ1.96(Ti2.68Nb0.41Fe{0.18/3+}Zr0.12)Σ3.39(Si3.95Al0.05)Σ4 20.31F0.18. The simplified formula is: Zn2Ti4- x Si4O14(OH,H2O,□)8 ( x < 1). Vigrishinite is triclinic, space group P , a = 8.743(9), b = 8.698(9), c = 11.581(11)Å, α = 91.54(8)°, β = 98.29(8)°, γ = 105.65(8)°, V = 837.2(1.5) Å3, Z = 2. The strongest reflections in the X-ray powder pattern ( d, Å, - I[ hkl]) are: 11.7-67[001], 8.27-50[100], 6.94-43[01, 10], 5.73-54[11, 002], 4.17-65[020, 2, 200], and 2.861-100[30, 22, 004, 11]. The crystal structure model was obtained on a single crystal, R = 0.171. Vigrishinite and murmanite are close in the structure of the TiSiO motif, but

  6. Discrimination of alkalinity in granitoid Rocks: A potential TIMS application

    NASA Technical Reports Server (NTRS)

    Ruff, Steven W.

    1995-01-01

    In mineral exploration, the ability to distinguish and map petrochemical variations of magmatic rocks can be a useful reconnaissance tool. Alkalinity is one such petrochemical parameter and is used in the characterization of granitoid rocks. In quartz normative plutonic rocks, alkalinity is related to the composition and abundance of feldspars. Together with quartz abundance, knowledge of feldspar modes allows the classification of these igneous rocks according to the Streckeisen diagram. Alternative classification schemes rely on whole rock geochemistry instead of mineral identifications. The relative ease of obtaining whole rock analyses means that geochemical classifications tend to be favored in exploration geology. But the technique of thermal infrared spectroscopy of rocks yields information on mineralogy and is one that can be applied remotely. The goal of the current work then is to establish whether data from TIMS can be used to distinguish the mineralogical variations that relate to alkalinity. An ideal opportunity to test this thesis arises from the work presented in a paper by Dewitt (1989). This paper contains the results of mapping and analysis of Proterozoic plutonic rocks in north-central Arizona. The map resulting from this work delineates plutons according to alkalinity in an effort to establish a trend or polarity in the regional magmatism. Also contained within this paper are brief descriptions of the mineralogy of half of the region's plutons. This combination of mineralogical and geochemical information was the rationale behind choosing this area as a site for TIMS over flights. A portion of the region centered on the northern Bradshaw Mountains was selected because it contains plutons of all three alkalinity classifications (alkali-calcic, calc-alkalic, and calic) present on DeWitt's map within a relatively small area. The site was flown in August of 1994 and the data received a few days before the writing of this manuscript. Most of this

  7. Crystallization trends of precursor pyroxene in ordinary chondrites: Implications for igneous origin of precursor

    NASA Technical Reports Server (NTRS)

    Fujita, T.; Kitamura, M.

    1994-01-01

    Various observations suggest that the precursor of the fine fragments and the relict pyroxene was formed by an igneous process in a grandparent body of the chondrite. Furthermore, the fact that the precursors appear as fragments in the matrix as well as relicts in the chondrule suggests a shock origin for the chondrite by collision of two or more bodies, which had already to some extent undergone igneous differentiation.

  8. The Iron Hill (Powderhorn) Carbonatite Complex, Gunnison County, Colorado - A Potential Source of Several Uncommon Mineral Resources

    USGS Publications Warehouse

    Van Gosen, Bradley S.

    2009-01-01

    A similar version of this slide show was presented on three occasions during 2008: two times to local chapters of the Society for Mining, Metallurgy, and Exploration (SME), as part of SME's Henry Krumb lecture series, and the third time at the Northwest Mining Association's 114th Annual Meeting, held December 1-5, 2008, in Sparks (Reno), Nevada. In 2006, the U.S. Geological Survey (USGS) initiated a study of the diverse and uncommon mineral resources associated with carbonatites and associated alkaline igneous rocks. Most of these deposit types have not been studied by the USGS during the last 25 years, and many of these mineral resources have important applications in modern technology. The author chose to begin this study at Iron Hill in southwestern Colorado because it is the site of a classic carbonatite complex, which is thought to host the largest known resources of titanium and niobium in the United States.

  9. Do the Columbia Hills of Gusev Crater Represent a Layered Igneous Intrusion on Mars?

    NASA Astrophysics Data System (ADS)

    Francis, D.

    2009-12-01

    The Martian Rover Spirit has now collected some 60 whole-rock chemical analyses on rock outcrops and boulders on its traverse from its landing site on the Gusev crater plains into the nearby Columbia Hills. Although Fe-rich “basaltic” compositions dominate the data set, there is a relatively wide range of mafic compositions that define a striking trend of increasing Fe with increasing Mg, and a small subset of ultramafic compositions at higher Mg. Although many of the analyzed samples have been shown to have experienced the effects of acidic chemical weathering, only the minor elements S, P, and K appear to have been seriously disturbed. Comparisons of analyses of rocks before and after abrasion suggests that it is unlikely that the co-variation between Fe and Mg in the Spirit whole rock analyses is a weathering effect. Despite the coherence of the array of Spirit data in Fe-Mg space, however, no plausible crystal fractionation model can explain the decrease in Fe with Mg within the mafic samples, nor relate the ultramafic samples to the mafic ones, if the samples of the data set are assumed to represent volcanic compositions defining a liquid line of descent. This reflects a fundamental inconsistency between the compositions of the olivine present (Fo~50-60), as estimated by Mössbauer analysis, and that predicted on the basis of Fe/Mg partitioning (Fo ~ 80). Positively correlated linear arrays in Fe - Mg space are, however, a common feature of whole rock data collected across cyclic feldspar-rich and mafic-rich cumulates in layered igneous intrusions. In such cyclically layered sequences, the whole rock compositions reflect magmatic crystal sorting, and scatter along mixing lines between the compositions of dominant cumulate phases. There is in fact a striking correspondence between the Fe-Mg array of Spirit data and those of dunite to troctolite cumulate layers in the Fe-rich Lac Raudot Troctolite Complex of the Grenville Province of Québec. If the Spirit

  10. Igneous geology of the Carlin trend, Nevada: The importance of Eocene magmatism in gold mineralization

    NASA Astrophysics Data System (ADS)

    Ressel, Michael Walter, Jr.

    Igneous rocks of five ages are present in the Carlin trend, Nevada, and include: (1) Paleozoic basalt of the Roberts Mountains allochthon, (2) the Jurassic (˜158 Ma) Goldstrike intrusive complex, which includes the Goldstrike diorite laccolith and abundant dikes and sills, (3) a Cretaceous (112 Ma) granite stock, (4) lavas and intrusions of the Emigrant Pass volcanic field and widespread epizonal plugs and dikes of Eocene (˜40-36 Ma) age that range from rhyolite through basalt, and (5) Miocene (15 Ma) rhyolite lava and tuff. Jurassic and Eocene igneous rocks are by far the most important volumetrically and are spatially associated with nearly all ore deposits of the Carlin trend. This study focuses on the field relations, isotopic dating, and geochemistry of Eocene dikes that intrude sedimentary rocks in many deposits of the Carlin trend, because they are the youngest pre-mineral rocks and have simpler alteration histories than other host rocks. In the Beast, Genesis, Deep Star, Betze-Post, Rodeo-Goldbug, Meikle-Griffin, and Dee-Storm deposits, Eocene dikes are altered, commonly mineralized, and locally constitute ore. Gold-bearing dikes and sedimentary rocks have similar ore mineralogy, including arsenian pyrite, marcasite, and arsenopyrite, with late barite and stibnite. At Beast, as much as half the ore is hosted in a 37.3 Ma rhyolite dike. Post-gold alunite is ˜18.6 Ma. At Meikle and Griffin, porphyritic dacite dikes yield concordant U/Pb zircon and 40Ar/39Ar biotite emplacement ages of ˜39.2 Ma, and illite from the same QSP-altered dacite, with as much 9 ppm Au, yields similar, although imprecise 40Ar/39Ar ages. Thus, gold mineralization at these deposits closely followed emplacement of Eocene dikes. Carlin-type gold deposits in northeastern Nevada have been variously interpreted as partly syngenetic with Paleozoic carbonate rocks, products of Mesozoic contraction and metamorphism with or without significant magmatism, and of Tertiary age and related or

  11. Aspects of igneous activity significant to a repository at Yucca Mountain, Nevada

    SciTech Connect

    Krier, D. J.; Perry, F. V.

    2004-01-01

    Location, timing, volume, and eruptive style of post-Miocene volcanoes have defined the volcanic hazard significant to a proposed high-level radioactive waste (HLW) and spent nuclear fuel (SNF) repository at Yucca Mountain, Nevada, as a low-probability, high-consequence event. Examination of eruptive centers in the region that may be analogueues to possible future volcanic activity at Yucca Mountain have aided in defining and evaluating the consequence scenarios for intrusion into and eruption above a repository. The probability of a future event intersecting a repository at Yucca Mountain has a mean value of 1.7 x 10{sup -8} per year. This probability comes from the Probabilistic Volcanic Hazard Assessment (PVHA) completed in 1996 and updated to reflect change in repository layout. Since that time, magnetic anomalies representing potential buried volcanic centers have been identified fiom magnetic surveys; however these potential buried centers only slightly increase the probability of an event intersecting the repository. The proposed repository will be located in its central portion of Yucca Mountain at approximately 300m depth. The process for assessing performance of a repository at Yucca Mountain has identified two scenarios for igneous activity that, although having a very low probability of occurrence, could have a significant consequence should an igneous event occur. Either a dike swarm intersecting repository drifts containing waste packages, or a volcanic eruption through the repository could result in release of radioactive material to the accessible environment. Ongoing investigations are assessing the mechanisms and significance of the consequence scenarios. Lathrop Wells Cone ({approx}80,000 yrs), a key analogue for estimating potential future volcanic activity, is the youngest surface expression of apparent waning basaltic volcanism in the region. Cone internal structure, lavas, and ash-fall tephra have been examined to estimate eruptive volume

  12. Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona: Implications for the sources of plutons and metals in porphyry copper deposits

    USGS Publications Warehouse

    Bouse, R.M.; Ruiz, J.; Titley, S.R.; Tosdal, R.M.; Wooden, J.L.

    1999-01-01

    Porphyry copper deposits in Arizona are genetically associated with Late Cretaceous and early Tertiary igneous complexes that consist of older intermediate volcanic rocks and younger intermediate to felsic intrusions. The igneous complexes and their associated porphyry copper deposits were emplaced into an Early Proterozoic basement characterized by different rocks, geologic histories, and isotopic compositions. Lead isotope compositions of the Proterozoic basement rocks define, from northwest to southeast, the Mojave, central Arizona, and southeastern Arizona provinces. Porphyry copper deposits are present in each Pb isotope province. Lead isotope compositions of Late Cretaceous and early Tertiary plutons, together with those of sulfide minerals in porphyry copper deposits and of Proterozoic country rocks, place important constraints on genesis of the magmatic suites and the porphyry copper deposits themselves. The range of age-corrected Pb isotope compositions of plutons in 12 Late Cretaceous and early Tertiary igneous complexes is 206Pb/204Pb = 17.34 to 22.66, 207Pb/204Pb = 15.43 to 15.96, and 208Pb/204Pb = 37.19 to 40.33. These Pb isotope compositions and calculated model Th/U are similar to those of the Proterozoic rocks in which the plutons were emplaced, thereby indicating that Pb in the younger rocks and ore deposits was inherited from the basement rocks and their sources. No Pb isotope differences distinguish Late Cretaceous and early Tertiary igneous complexes that contain large economic porphyry copper deposits from less rich or smaller deposits that have not been considered economic for mining. Lead isotope compositions of Late Cretaceous and early Tertiary plutons and sulfide minerals from 30 metallic mineral districts, furthermore, require that the southeastern Arizona Pb province be divided into two subprovinces. The northern subprovince has generally lower 206Pb/204Pb and higher model Th/U, and the southern subprovince has higher 206Pb/204Pb and

  13. Evaluation of and new completion recommendations for a fractured, crystalline, igneous reservoir, Texas Panhandle

    SciTech Connect

    Weimer, B.A.; Manwaring, M.S. )

    1987-02-01

    In the Panhandle field of Texas, the lowest stratigraphic producing formation is a crystalline basement rock. The igneous rock is productive when it is naturally fractured sufficiently to hold hydrocarbons trapped in the same structure as the expansive Panhandle field. Research work to understand the crystalline reservoir better focused on the fracturing, mineralogy, and production potential of the basement interval. This trap is a true fractured reservoir; it has no more than 1% primary porosity in the nonfractured rock. The mineralogy of the host rock and fracture-filling minerals was established from drill and core samples. The host rock is a complex of granodiorite, dacite, and gabbroic diorite. Scanning electron microscopy, x-ray diffraction, and optical work confirmed the occurrence of at least 12 secondary fracture-fill minerals. Fluid inclusion analysis established formation temperatures for many of the minerals and allowed postulation of a detailed sequence of formation. The character of the fracture in differing host petrologies and the occurrence of clay minerals coating fracture surfaces were deemed to be critical factors in hydrocarbon production. New and specific enhancement treatments were designed for the subject reservoir, and these recommendations were used in a test well. Results from the test were favorable and appear to confirm the ideas formed from this work. The new recommended treatments are less expensive than current practices and indicate potential for greater ultimate recoveries of oil.

  14. Thermal aureoles of igneous intrusions: some possible indications of hydrothermal convective cooling

    SciTech Connect

    Parmentier, E.M.; Schedl, A.

    1981-01-01

    The size and shape of metamorphic aureoles is investigated as a possible indicator of hydrothermal convective cooling of epizonal igneous intrusions. A simple family of numerical models illustrates the effect of convective cooling on maximum temperatures attained in the country rock surrounding an intrusion. Boundary layer approximations have also been applied to describe convection of vaporizing groundwater near the contact of an intrusion early in its cooling history. Maximum temperature isotherms are taken to reflect the width and shape of thermal aureoles defined by preserved mineral assemblages as appears to be reasonable based on several well-studied conductively cooled intrusions. The thermal aureoles of intrusions for which oxygen and hydrogen isotope data indicate convective groundwater circulation have been examined on the basis of the simple numerical and boundary layer models. The shape of the low temperature alteration aureole of the well-mapped El Salvador porphyry copper deposit suggests convective cooling of a permeable intrusion. The width of the low temperature (greenschist) aureole of the Mull intrusive complex can be explained by convective cooling of permeable intrusive rock. The narrow high temperature (amphibolite) aureole of the Cuillin gabbro on Skye can be explained by strong convective cooling; but the low temperature (greenschist) aureole is wide enough to be consistent with conductive cooling, thus suggesting decreasing permeabilities during the cooling history. This is consistent with oxygen isotope sampling and other geologic observations.

  15. The Late Ordovician crisis: the Large Igneous Province hypothesis tested by global carbon cycle modeling.

    NASA Astrophysics Data System (ADS)

    Lefebvre, Vincent; Servais, Thomas; François, Louis; Averbuch, Olivier

    2010-05-01

    The causes of the well-known Late Ordovician-Hirnantian glaciation remain largely debated. This global cooling event is generally attributed to a severe decrease of atmospheric pCO2 during a time of general greenhouse climate but its duration is not fully determined. The climate perturbation is synchronous with one of the biggest biotic crisis of the Earth history. Some authors have shown that, considering the Ashgillian paleogeography, a drop in pCO2 below a threshold of 8x to 10x PAL (Present Atmospheric Level) may induce a decrease in temperature in high latitudes so that the installation of an ice-sheet on Gondwana could be possible. Such a process requires an intensification of silicate weathering and/or organic carbon burial that are the two major processes potentially driving a decrease in atmospheric pCO2 at the geologic time scale. The Late Ordovician is known to be a period of high mantellic activity marked by a lack of reversal magnetic field and high volcanic activity. Barnes (2004) and Courtillot and Olson (2007) link this process to a superplume event that may give rise to continental basalt flooding. In the present study, we tested this hypothesis with a global carbon cycle numerical box-model coupled with an Energy Balance Climate Model. The Model is an upgrade of that used by Grard et al. (2005) to simulate the environmental impact of the Siberian traps at the P/T boundary. The configuration of the box-model has been set using the Late Ordovician paleogeography. In each oceanic box, the model calculates the evolution of carbon, phosphorus and oxygen concentrations and alkalinity. It also calculates atmospheric pCO2, atmospheric and oceanic δ13C. We tested different scenarios of Large Igneous Province (LIP) emplacements and organic carbon cycle interactions simulating atmospheric pCO2 drops of amplitude large enough to produce the Hirnantian glaciation. We show that the hypothesis of low latitude LIP well accounts for the Late Ordovician climate

  16. "Fingerprinting" tectono-magmatic provenance using trace elements in igneous zircon

    NASA Astrophysics Data System (ADS)

    Grimes, C. B.; Wooden, J. L.; Cheadle, M. J.; John, B. E.

    2015-12-01

    Over 5300 recent SHRIMP-RG analyses of trace elements (TE) in igneous zircon have been compiled and classified based on their original tectono-magmatic setting to empirically evaluate "geochemical fingerprints" unique to those settings. Immobile element geochemical fingerprints used for lavas are applied with the same rational to zircon, including consideration of mineral competition on zircon TE ratios, and new criteria for distinguishing mid-ocean ridge (MOR), magmatic arc, and ocean island (and other plume-influenced) settings are proposed. The elemental ratios in zircon effective for fingerprinting tectono-magmatic provenance are systematically related to lava composition from equivalent settings. Existing discrimination diagrams using zircon U/Yb versus Hf or Y do not distinguish TE-enriched ocean island settings (i.e., Iceland, Hawaii) from magmatic arc settings. However, bivariate diagrams with combined cation ratios involving U-Nb-Sc-Yb-Gd-Ce provide a more complete distinction of zircon from these settings. On diagrams of U/Yb versus Nb/Yb, most MOR, ocean island, and kimberlite zircon define a broad "mantle-zircon array"; arc zircon defines a parallel array offset to higher U/Yb. Distinctly low U/Yb ratios of MOR zircon (typically <0.1) mirror their parental magmas and long-term incompatible element depletion of the MORB mantle. Plume-influenced sources are distinguished from MOR by higher U/Yb, U/Nb, Nb/Yb, and Nb/Sc. For zircon with U/Yb > 0.1, high Sc/Yb separates arc settings from low-Sc/Yb plume-influenced sources. The slope of scandium enrichment trends in zircon differ between MOR and continental arc settings, likely reflecting the involvement of amphibole during melt differentiation. Scandium is thus also critical for discriminating provenance, but its behavior in zircon probably reflects contrasting melt fractionation trends between tholeiitic and calc-alkaline systems more than compositional differences in primitive magmas sourced at each

  17. Survey of Large, Igneous-Textured Inclusions in Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Armstrong, K.; Ruzicka, A. M.

    2013-12-01

    Ordinary (O) chondrites are a class of primitive stony meteorites, and as a group comprise our most abundant samples of early solar system materials. Unique to O chondrites are igneous-textured inclusions up to 4 cm in diameter; about an order of magnitude larger than the much more abundant chondrules. These inclusions are almost always highly depleted in metal and sulfide relative to their host meteorite, but but otherwise have diverse characteristics. They exhibit a large range of textures, mineralogies, and bulk compositions, suggesting a variety of formation processes. They all crystallized from large melt volumes, the origins of which are poorly understood. Models proposed for their formation include (1) shock melting of ordinary chondrites with an associated loss of metal and sulfide; (2) melting of vapor-fractionated condensate mixture; (3) chondrule formation involving a larger melt production volume than typical for chondrules; and (4) igneous differentiation occurring within planetesimals sampled by ordinary chondrite parent bodies. Polished thin sections of inclusions from several O-chondrites have been examined with optical light microscopy (OLM) using a Leica DM 2500 petrographic microscope. Petrographic data such as texture, grain sizes and shapes were collected for the inclusions and their hosts in order to facilitate comparisons. Texturally, the inclusions were determined to fall into one of three distinct textural categories: porphyritic, fine granular, and skeletal. Mean grain sizes are on the order of 100 um for both microporphyritic and fine granular inclusions, with microporphyritic inclusions showing a much wider range of grain sizes. The largest grains in the microporphyritic inclusions are on average ~0.25 mm, with the grains of the mesostasis <100 microns. Skeletal olivine textures are defined as being dominated by crystals that are an order of magnitude longer across one direction than the other (e.g., 1 mm x 100 um). Five inclusions have

  18. Integrating isotopic fingerprinting with petrology: how do igneous rocks evolve?

    NASA Astrophysics Data System (ADS)

    Davidson, J. P.

    2002-12-01

    In the title of his seminal work, N.L. Bowen recognized the fundamental importance of magmatic evolution in producing the spectrum of igneous rocks. Indeed it is difficult to imagine a hot highly reactive fluid passing through c. 100 km of a chemically distinct medium (lithosphere) without evolving through cooling, crystallization and interaction with the wall rocks. The fact that magmas evolve - almost invariably through open system processes - has been largely marginalized in the past 30 years by the desire to use them as probes of mantle source regions. This perspective has been driven principally by advances offered by isotope geochemistry, through which components and sources can be effectively fingerprinted. Two fundamental observations urge caution in ignoring differentiation effects; 1) the scarcity of truly primary magmas according to geochemical criteria (recognized long ago by petrologists), and 2) the common occurrence of petrographic criteria attesting to open system evolution. Recent advances in multicollector mass spectrometry permit integration of the powerful diagnostic tools of isotope geochemistry with petrographic observations through accurate and precise analysis of small samples. Laser ablation and microdrilling enable sampling within and between mineral phases. The results of our microsampling investigations give widespread support for open system evolution of magmas, and provide insights into the mechanisms and timescales over which this occurs. For example; 1) core-rim decreases in 87Sr/86Sr in zoned plagioclase crystals from 1982 lavas of El Chichon volcano, Mexico, argue that the zoning and isotopic changes are in response to magma recharge mixing with an originally contaminated resident magma; 2) Single grain and intra-grain isotopic analyses of mineral phases from Ngauruhoe andesites (New Zealand) are highly variable, arguing that bulk rock data reflect mechanical aggregations of components which have evolved in discrete domains of the

  19. Characterize Framework for Igneous Activity at Yucca Mountain, Nevada

    SciTech Connect

    F. Perry; R. Youngs

    2004-10-14

    The purpose of this scientific analysis report is threefold: (1) Present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) consistent with the volcanic and tectonic history of this region and the assessment of this history by experts who participated in the probabilistic volcanic hazard analysis (PVHA) (CRWMS M&O 1996 [DIRS 100116]). Conceptual models presented in the PVHA are summarized and applied in areas in which new information has been presented. Alternative conceptual models are discussed, as well as their impact on probability models. The relationship between volcanic source zones defined in the PVHA and structural features of the YMR are described based on discussions in the PVHA and studies presented since the PVHA. (2) Present revised probability calculations based on PVHA outputs for a repository footprint proposed in 2003 (BSC 2003 [DIRS 162289]), rather than the footprint used at the time of the PVHA. This analysis report also calculates the probability of an eruptive center(s) forming within the repository footprint using information developed in the PVHA. Probability distributions are presented for the length and orientation of volcanic dikes located within the repository footprint and for the number of eruptive centers (conditional on a dike intersecting the repository) located within the repository footprint. (3) Document sensitivity studies that analyze how the presence of potentially buried basaltic volcanoes may affect the computed frequency of intersection of the repository footprint by a basaltic dike. These sensitivity studies are prompted by aeromagnetic data collected in 1999, indicating the possible presence of previously unrecognized buried volcanoes in the YMR (Blakely et al. 2000 [DIRS 151881]; O'Leary et al. 2002 [DIRS 158468]). The results of the sensitivity studies are for informational purposes only and are not to be used for purposes of assessing repository performance.

  20. Thermal conductivity anisotropy of metasedimentary and igneous rocks

    NASA Astrophysics Data System (ADS)

    Davis, Michael G.; Chapman, David S.; van Wagoner, Thomas M.; Armstrong, Phillip A.

    2007-05-01

    Thermal conductivity anisotropy was determined for three sets of metasedimentary and igneous rocks from central Utah, USA. Most conductivity measurements were made in transient mode with a half-space, line source instrument oriented in two orthogonal directions on a flat face cut perpendicular to bedding. One orientation of the probe yields thermal conductivity parallel to bedding (kpar) directly, the other orientation of the probe measures a product of conductivities parallel and perpendicular to bedding from which the perpendicular conductivity (kperp) is calculated. Some direct measurements of kpar and kperp were made on oriented cylindrical discs using a conventional divided bar device in steady state mode. Anisotropy is defined as kpar/kperp. Precambrian argillites from Big Cottonwood Canyon have anisotropy values from 0.8 to 2.1 with corresponding conductivity perpendicular to bedding of 2.0 to 6.2 W m-1 K-1. Anisotropy values for Price Canyon sedimentary samples are less than 1.2 with a mean of 1.04 although thermal conductivity perpendicular to bedding for the samples varied from 1.3 to 5.0 W m-1 K-1. The granitic rocks were found to be essentially isotropic with thermal conductivity perpendicular to bedding having a range of 2.2 to 3.2 W m-1 K-1 and a mean of 2.68 W m-1 K-1. The results confirm the observation by Deming [1994] that anisotropy is negligible for rocks having kperp greater than 4.0 W m-1 K-1 and generally increases for low conductivity metamorphic and clay-rich rocks. There is little evidence, however, for his suggestion that thermal conductivity anisotropy of all rocks increases systematically to about 2.5 for low thermal conductivity rocks.

  1. Linking mantle plumes, large igneous provinces and environmental catastrophes.

    PubMed

    Sobolev, Stephan V; Sobolev, Alexander V; Kuzmin, Dmitry V; Krivolutskaya, Nadezhda A; Petrunin, Alexey G; Arndt, Nicholas T; Radko, Viktor A; Vasiliev, Yuri R

    2011-09-14

    Large igneous provinces (LIPs) are known for their rapid production of enormous volumes of magma (up to several million cubic kilometres in less than a million years), for marked thinning of the lithosphere, often ending with a continental break-up, and for their links to global environmental catastrophes. Despite the importance of LIPs, controversy surrounds even the basic idea that they form through melting in the heads of thermal mantle plumes. The Permo-Triassic Siberian Traps--the type example and the largest continental LIP--is located on thick cratonic lithosphere and was synchronous with the largest known mass-extinction event. However, there is no evidence of pre-magmatic uplift or of a large lithospheric stretching, as predicted above a plume head. Moreover, estimates of magmatic CO(2) degassing from the Siberian Traps are considered insufficient to trigger climatic crises, leading to the hypothesis that the release of thermogenic gases from the sediment pile caused the mass extinction. Here we present petrological evidence for a large amount (15 wt%) of dense recycled oceanic crust in the head of the plume and develop a thermomechanical model that predicts no pre-magmatic uplift and requires no lithospheric extension. The model implies extensive plume melting and heterogeneous erosion of the thick cratonic lithosphere over the course of a few hundred thousand years. The model suggests that massive degassing of CO(2) and HCl, mostly from the recycled crust in the plume head, could alone trigger a mass extinction and predicts it happening before the main volcanic phase, in agreement with stratigraphic and geochronological data for the Siberian Traps and other LIPs.

  2. Complexity.

    PubMed

    Gómez-Hernández, J Jaime

    2006-01-01

    It is difficult to define complexity in modeling. Complexity is often associated with uncertainty since modeling uncertainty is an intrinsically difficult task. However, modeling uncertainty does not require, necessarily, complex models, in the sense of a model requiring an unmanageable number of degrees of freedom to characterize the aquifer. The relationship between complexity, uncertainty, heterogeneity, and stochastic modeling is not simple. Aquifer models should be able to quantify the uncertainty of their predictions, which can be done using stochastic models that produce heterogeneous realizations of aquifer parameters. This is the type of complexity addressed in this article.

  3. The igneous charnockite-high-K alkali-calcic I-type granite-incipient charnockite association in Trivandrum Block, southern India

    NASA Astrophysics Data System (ADS)

    Rajesh, H. M.

    The Pan-African (640 Ma) Chengannoor granite intrudes the NW margin of the Neoproterozoic high-grade metamorphic terrain of the Trivandrum Block (TB), southern India, and is spatially associated with the Cardamom hills igneous charnockite massif (CM). Geochemical features characterize the Chengannoor granite as high-K alkali-calcic I-type granite. Within the constraints imposed by the high temperature, anhydrous, K-rich nature of the magmas, comparison with recent experimental studies on various granitoid source compositions, and trace- and rare-earth-element modelling, the distinctive features of the Chengannoor granite reflect a source rock of igneous charnockitic nature. A petrogenetic model is proposed whereby there was a period of basaltic underplating; the partial melting of this basaltic lower crust formed the CM charnockites. The Chengannoor granite was produced by the partial melting of the charnoenderbites from the CM, with subsequent fractionation dominated by feldspars. In a regional context, the Chengannoor I-type granite is considered as a possible heat source for the near-UHT nature of metamorphism in the northern part of the TB. This is different from previous studies, which favoured CM charnockite as the major heat source. The occurrence of incipient charnockites (both large scale as well as small scale) adjacent to the granite as well as pegmatites (which contain CO2, CO2-H2O, F and other volatiles), suggests that the fluids expelled from the alkaline magma upon solidification generated incipient charnockites through fluid-induced lowering of water activity. Thus the granite and associated alkaline pegmatites acted as conduits for the transfer of heat and volatiles in the Achankovil Shear Zone area, causing pervasive as well as patchy charnockite formation. The transport of CO2 by felsic melts through the southern Indian middle crust is suggested to be part of a crustal-scale fluid system that linked mantle heat and CO2 input with upward migration

  4. [High Precision Identification of Igneous Rock Lithology by Laser Induced Breakdown Spectroscopy].

    PubMed

    Wang, Chao; Zhang, Wei-gang; Yan, Zhi-quan

    2015-09-01

    In the field of petroleum exploration, lithology identification of finely cuttings sample, especially high precision identification of igneous rock with similar property, has become one of the geological problems. In order to solve this problem, a new method is proposed based on element analysis of Laser-Induced Breakdown Spectroscopy (LIBS) and Total Alkali versus Silica (TAS) diagram. Using independent LIBS system, factors influencing spectral signal, such as pulse energy, acquisition time delay, spectrum acquisition method and pre-ablation are researched through contrast experiments systematically. The best analysis conditions of igneous rock are determined: pulse energy is 50 mJ, acquisition time delay is 2 μs, the analysis result is integral average of 20 different points of sample's surface, and pre-ablation has been proved not suitable for igneous rock sample by experiment. The repeatability of spectral data is improved effectively. Characteristic lines of 7 elements (Na, Mg, Al, Si, K, Ca, Fe) commonly used for lithology identification of igneous rock are determined, and igneous rock samples of different lithology are analyzed and compared. Calibration curves of Na, K, Si are generated by using national standard series of rock samples, and all the linearly dependent coefficients are greater than 0.9. The accuracy of quantitative analysis is investigated by national standard samples. Element content of igneous rock is analyzed quantitatively by calibration curve, and its lithology is identified accurately by the method of TAS diagram, whose accuracy rate is 90.7%. The study indicates that LIBS can effectively achieve the high precision identification of the lithology of igneous rock.

  5. The behaviour of copper isotopes during igneous processes

    NASA Astrophysics Data System (ADS)

    Savage, P. S.; Moynier, F.; Harvey, J.; Burton, K. W.

    2015-12-01

    Application of Cu isotopes to high temperature systems has recently gained momentum and has the potential for probing sulphide fractionation during planetary differentiation [1]. This requires robust estimates for planetary reservoirs, and a fundamental understanding of how igneous processes affect Cu isotopes; this study aims to tackle the latter. Cogenetic suites affected by both fractionation crystallisation and cumulate formation were analysed to study such effects on Cu isotopes. In S-undersatured systems, Cu behaves incompatibly during melt evolution and the Cu isotope composition of such melt is invariant over the differentiation sequence. In contrast, S-saturated systems show resolvable Cu isotope variations relative to primitive melt. Such variations are minor but imply a slightly heavy Cu isotope composition for continental crust compared to BSE, consistent with granite data [2]. Although olivine accumulation does not affect Cu isotopes, spinel-hosted Cu is isotopically light relative to the bulk. Analysis of variably melt-depleted cratonic peridotites shows that partial melting can affect Cu isotope composition in restite, with the depleted samples isotopically light compared to BSE. This could be due to residual spinel and/or incongruent melting of sulphides - individual sulphides picked from a single xenolith reveal a range of Cu isotope compositions, dependent on composition. Although partial melting may fractionate Cu isotopes, models suggest most mantle-derived melt will have δ65Cu ≈ BSE, as most source Cu will be transferred to the melt. Small degree melts such as ocean island basalts are predicted to be isotopically heavier than MORB, if derived from a primitive mantle source. OIBs have a range of Cu isotope compositions: some are heavier than MORB as predicted; however, some have much lighter compositions. Since Cu isotopes can be significantly fractionated in the surface environment [e.g. 3] OIB Cu isotopic variations may be linked to

  6. Pristine Igneous Rocks and the Early Differentiation of Planetary Materials

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.

    1998-01-01

    Our studies are highly interdisciplinary, but are focused on the processes and products of early planetary and asteroidal differentiation, especially the genesis of the ancient lunar crust. Most of the accessible lunar crust consists of materials hybridized by impact-mixing. Rare pristine (unmixed) samples reflect the original genetic diversity of the early crust. We studied the relative importance of internally generated melt (including the putative magma ocean) versus large impact melts in early lunar magmatism, through both sample analysis and physical modeling. Other topics under investigation included: lunar and SNC (martian?) meteorites; igneous meteorites in general; impact breccias, especially metal-rich Apollo samples and polymict eucrites; effects of regolith/megaregolith insulation on thermal evolution and geochronology; and planetary bulk compositions and origins. We investigated the theoretical petrology of impact melts, especially those formed in large masses, such as the unejected parts of the melts of the largest lunar and terrestrial impact basins. We developed constraints on several key effects that variations in melting/displacement ratio (a strong function of both crater size and planetary g) have on impact melt petrology. Modeling results indicate that the impact melt-derived rock in the sampled, megaregolith part of the Moon is probably material that was ejected from deeper average levels than the non-impact-melted material (fragmental breccias and unbrecciated pristine rocks). In the largest lunar impacts, most of the impact melt is of mantle origin and avoids ejection from the crater, while most of the crust, and virtually all of the impact-melted crust, in the area of the crater is ejected. We investigated numerous extraordinary meteorites and Apollo rocks, emphasizing pristine rocks, siderophile and volatile trace elements, and the identification of primary partial melts, as opposed to partial cumulates. Apollo 15 sample 15434,28 is an

  7. The pre-Caledonian Large Igneous Province and the North Atlantic Wilson Cycle

    NASA Astrophysics Data System (ADS)

    Tegner, Christian; Andersen, Torgeir B.; Corfu, Fernando; Planke, Sverre; Jørgen Kjøll, Hans; Torsvik, Trond H.

    2016-04-01

    Magmatism of the first known rifting phase of the North Atlantic Wilson Cycle is surprisingly well preserved in the Caledonian nappes of central Scandinavia. The Särv and Seve Nappes are characterised by spectacular dyke complexes originally emplaced into continental sediments along the rifted margin of Iapetus. The intensity and structure of the pre-Caledonian Dyke Complex is comparable to that of the present passive margins of the North Atlantic large igneous province (NALIP) and U-Pb ages of 610-590 Ma suggest magmatism was short-lived. It can be described as a pre-Caledonian large igneous province (CLIP). To constrain the origin of CLIP magmatism we: (1) re-visited the dyke complexes of the Sarek, Kebnekaise and Tornetrask mountains of North Sweden; (2) compiled new and published geochemical data for the more than 950 km long, magma-rich segment of the Scandinavian Caledonides; and (3) extended reconstructions of the paleo-position of Baltica back to 600 Ma. Although the appearance of the dykes ranges from garnet amphibolite gneiss to pristine magmatic intrusions, all bulk rock compositions largely reflect the original magmatic rock. The compiled dataset includes 584 analyses that essentially forms a coherent suite of tholeiitic ferrobasalt (2-12 wt% MgO, 45-54 wt% SiO2; 6-16 wt% FeOtot; 0.7-4.0 wt% TiO2) akin to LIP basalts such as those of NALIP (61-54 Ma). A few samples (<20) are significantly contaminated with crust, but most are largely uncontaminated. The delta Nb value is a proxy for geochemical enrichment based on Nb-Zr-Y systematics and was defined for the present-day North Atlantic system to distinguish enriched Iceland basalts (positive delta Nb) from normal MORB basalts (negative delta Nb). The CLIP dykes are dominantly enriched with positive delta Nb (-0.07 to +0.9) in the central and southern portion, but stretching to more negative values (-0.6 to +0.5) in the northern portion (Sarek, Kebnekaise, Tornetrask). The few available rare earth element

  8. Hydrocarbon occurrences in igneous and metamorphic rocks: Plays of the 1990s

    SciTech Connect

    Harrelson, D.W.

    1989-09-01

    A review of available geologic literature has indicated numerous references detailing the occurrences of hydrocarbon in igneous and metamorphic rocks. Notable among these references is a paper by Chung-Hsiang P'an and a group of papers edited by Sidney Powers. Collectively, these papers conclude a biogenic source for hydrocarbons, most of which occur in (1) weathered igneous and metamorphic reservoir rocks that are higher than the source rocks (e.g., Amarillo field) or (2) igneous and metamorphic rocks that exert structural or stratigraphic control on the reservoir or source rocks (e.g., Jackson dome and the Wiggins anticline-Hancock ridge). It should be noted that a new twist on the abiogenic origin of some inert hydrocarbon gases (i.e., helium and nitrogen) proposes a degassing of igneous and metamorphic rocks from sources in the underlying mantle. Recent european super-deep tests (e.g., the Siljan Ring and the Kola SG-3 testholes) have attempted, with mixed results, to verify this theory. Drilling for these deep igneous and metamorphic prospects today is considered at or below economic basement or worse - a rank wildcat. However, these plays should become increasingly commercial in the 1990s as deeper drilling technology progresses, the current oil glut is eliminated, and more exotic deep gas prospects become accepted.

  9. Middle Jurassic to early Cretaceous igneous rocks along eastern North American continental margin

    SciTech Connect

    Jansa, L.F.; Pe-Piper, G.

    1988-03-01

    Late Middle Jurassic and Early Cretaceous mafic dikes, sills, flows, and local volcaniclastic sediments are intercalated within continental shelf sediments from the Baltimore Canyon Trough northward to the Grand Banks of Newfoundland. The igneous rocks on the eastern North American margin are mainly alkali basalts of intraplate affinity. The late Middle Jurassic igneous activity was of short duration, at about 140 Ma, and was restricted to Georges Bank where it led to construction of several volcanic cones. The main period of igneous activity was concentrated at about 120 Ma in the Aptian/Berremian. The activity consists of dike swarms in Baltimore Canyon, occasional dikes on the Scotian Shelf, and the growth of stratovolcanoes on the Scotian Shelf and Grand Banks. Younger dikes (approx. 95 Ma) also are present on the Grand Banks. With regard to oil exploration on the continental margin, care must be taken to properly identify igneous and volcaniclastic rocks on mechanical logs, drill cuttings, and cores. Reflection seismic profiles can be used to map the areal extent of sills, flows, and low-angle dikes, which commonly show distinctive seismic responses. However, steeply dipping dikes generally produce little, if any, seismic response. Isotopic-age determinations of igneous rocks, combined with biostratigraphic-age determinations of adjacent strata, are invaluable for stratigraphic correlation, establishing chronology of seismic sequences, and analysis of basin sedimentation and tectonic history. 9 figures, 2 tables.

  10. Early and Late Alkali Igneous Pulses and a High-3He Plume Origin for the Deccan Flood Basalts.

    PubMed

    Basu, A R; Renne, P R; Dasgupta, D K; Teichmann, F; Poreda, R J

    1993-08-13

    Several alkalic igneous complexes of nephelinite-carbonatite affinities occur in extensional zones around a region of high heat flow and positive gravity anomaly within the continental flood basalt (CFB) province of Deccan, India. Biotites from two of the complexes yield (40)Ar/(39)Ar dates of 68.53 +/- 0.16 and 68.57 +/- 0.08 million years. Biotite from a third complex, which intrudes the flood basalts, yields an (40)Ar/(39)Ar date of 64.96 +/- 0.1 1 million years. The complexes thus represent early and late magmatism with respect to the main pulse of CFB volcanism 65 million years ago. Rocks from the older complexes show a (3)He/(4)He ratio of 14.0 times the air ratio, an initial (87)Sr/(86)Sr ratio of 0.70483, and other geochemical characteristics similar to ocean island basalts; the later alkalic pulse shows isotopic evidence of crustal contamination. The data document 3.5 million years of incubation of a primitive, high-(3)He mantle plume before the rapid eruption of the Deccan CFB.

  11. Heat production rate from radioactive elements in igneous and metamorphic rocks in Eastern Desert, Egypt.

    PubMed

    Abbady, Adel G E; El-Arabi, A M; Abbady, A

    2006-01-01

    Radioactive heat-production data of Igneous and Metamorphic outcrops in the Eastern Desert are presented. Samples were analysed using a low level gamma-ray spectrometer (HPGe) in the laboratory. A total of 205 rock samples were investigated, covering all major rock types of the area. The heat-production rate of igneous rocks ranges from 0.11 (basalt) to 9.53 microWm(-3) (granite). In metamorphic rocks it varies from 0.28 (serpentinite ) to 0.91 microWm(-3) (metagabbro). The contribution due to U is about 51%, as that from Th is 31% and 18% from K. The corresponding values in igneous rocks are 76%, 19% and 5%, respectively. The calculated values showed good agreement with global values except in some areas containing granites.

  12. Timing and chemistry of igneous events associated with the Southern Oklahoma Aulacogen

    NASA Astrophysics Data System (ADS)

    Charles Gilbert, M.

    1983-05-01

    Igneous activity in the Southern Oklahoma Aulacogen of North America was concentrated in the early rifting stages of aulacogen development. The time span over which liquids rose may not have exceeded 50 m.y. and certainly terminated before the Upper Cambrian. Igneous activity began with three basaltic liquids, stratigraphically identifiable but perhaps not all distinct genetically. This was followed by one large rhyolitic-granitic episode of A-type character. One final basaltic event ended the activity. All the basaltic types seem to be tholeiitic showing more kinship with either the older, Proterozoic North American Midcontinental Rift or the northern part of the Cenozoic Rio Grande Rift, than the Cenozoic East African Rift. Two major uplifts occurred: one between the earlier basalts and the rhyolite, and one much later, after all igneous activity was over, in the Pennsylvanian.

  13. New low-Ni (igneous?) particles among the C and C? types of cosmic dust

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Sutton, S. R.; Bajt, S.; Kloeck, W.

    1993-01-01

    Low-Ni particles with major element abundances, optical properties, and morphologies sufficiently similar to chondritic interplanetery dust particles (IDP's) to receive JSC Cosmic Dust Catalog classifications of C or C?-types were shown to have trace element contents and mineralogies similar to igneous material. Examination of the JSC Catalog EDX spectra by Cooke et al. has shown that 13 percent of the C-type and 38 percent of the C?-type particles are potentially low-Ni particles. Two new low-Ni particles were identified, and it was shown that an additional fragment from the L2002*C cluster has an igneous composition. A newly analyzed fragment of the W7066*A cluster has a chondritic composition. The W7066*A cluster is important because it has yielded a fragment of igneous composition and another fragment having high concentrations of He and Ne suggesting an extraterrestrial origin.

  14. Igneous history of the aubrite parent asteroid - evidence from the Norton County enstatite achondrite

    SciTech Connect

    Okada, A.; Keil, K.; Taylor, G.J.; Newsom, H.

    1988-03-01

    Numerous specimens of the Norton County enstatite achondrite (aubrite) were studied by optical microscopy, electron microprobe, and neutron-activation analysis. Norton County is found to be a fragmental impact breccia, consisting of a clastic matrix made mostly of crushed enstatite, into which are embedded a variety of mineral and lithic clasts of both igneous and impact melt origin. The Norton County precursor materials were igneous rocks, mostly plutonic orthopyroxenites, not grains formed by condensation from the solar nebula. The Mg-silicate-rich aubrite parent body experienced extensive melting and igneous differentiation, causing formation of diverse lithologies including dunites, plutonic orthopyroxenites, plutonic pyroxenites, and plagioclase-silica rocks. The presence of impact melt breccias (the microporphyritic clasts and the diopside-plagioclase-silica clast) of still different compositions further attests to the lithologic diversity of the aubrite parent body. 60 references.

  15. Igneous history of the aubrite parent asteroid - Evidence from the Norton County enstatite achondrite

    NASA Technical Reports Server (NTRS)

    Okada, Akihiko; Keil, Klaus; Taylor, G. Jeffrey; Newsom, Horton

    1988-01-01

    Numerous specimens of the Norton County enstatite achondrite (aubrite) were studied by optical microscopy, electron microprobe, and neutron-activation analysis. Norton County is found to be a fragmental impact breccia, consisting of a clastic matrix made mostly of crushed enstatite, into which are embedded a variety of mineral and lithic clasts of both igneous and impact melt origin. The Norton County precursor materials were igneous rocks, mostly plutonic orthopyroxenites, not grains formed by condensation from the solar nebula. The Mg-silicate-rich aubrite parent body experienced extensive melting and igneous differentiation, causing formation of diverse lithologies including dunites, plutonic orthopyroxenites, plutonic pyroxenites, and plagioclase-silica rocks. The presence of impact melt breccias (the microporphyritic clasts and the diopside-plagioclase-silica clast) of still different compositions further attests to the lithologic diversity of the aubrite parent body.

  16. Paleozoic to Triassic ocean opening and closure preserved in Central Iran: Constraints from the geochemistry of meta-igneous rocks of the Anarak area

    NASA Astrophysics Data System (ADS)

    Buchs, David M.; Bagheri, Sasan; Martin, Laure; Hermann, Joerg; Arculus, Richard

    2013-07-01

    The Anarak area belongs to an ophiolitic belt along the northern border of the Central-East Iranian Microcontinent, and is thought to contain fragments of the former Paleotethys and Neotethys oceans. A wide range of meta-igneous rocks from the Late Paleozoic to Triassic Anarak Metamorphic Complex (AMC) and nearby Meraji area have been studied to constrain the origins and modes of emplacement of oceanic remnants in Central Iran. Our samples occur as layers and lenses embedded in extensive sequences of deformed meta-sediments and smaller bodies of serpentinized ultramafic rocks. Petrographical and geochemical data combined with field and satellite observations allow recognition of seven types of meta-igneous rocks preserved from low grade to blueschist facies conditions. Their origins based on relative abundances of immobile trace elements include subduction zone, mid-ocean ridge, ocean intraplate, and continental rift settings. These data and existing geochronological constraints show the AMC formed an accretionary complex formed/exhumed incrementally during the Carboniferous, Permo-triassic and Triassic. Igneous rocks from Meraji formed in the Early Devonian due to opening of the Paleotethys, and belong to a rift sequence extending over 300 km along the edge of the Central-East Iranian Microcontinent. The AMC and nearby rock associations record the evolution of the Paleotethys during a complete Wilson Cycle between ca. 450 and 225 Ma, with implications for: (1) continental rifting; (2) ocean opening; (3) subduction initiation; (4) ocean intraplate and continued mid-ocean volcanism; (5) ridge subduction; and (6) final closure of the ocean during continent-continent collision. Alternate interpretations of the Anarak metabasites are possible, but require radical departures from the widely accepted model for tectonic evolution of the Paleotethys, with the existence of Paleotethyan backarc basin(s) and Permian or earlier collision of continental blocks in Central Iran

  17. Crystal Size Distributions in Igneous rocks: Where are we now?

    NASA Astrophysics Data System (ADS)

    Higgins, M.

    2003-12-01

    in either slope of intercept is significant and can be related to other parameters. Concave down CSDs, with no small crystals, are commonly encountered in porphyritic, oikocrystic and plutonic rocks. This texture may be produced by textural coarsening (Ostwald ripening, annealing): this occurs when the magma is maintained close to the mineral liquidus. In this situation the nucleation rate is zero, but growth rates are significant. The classic LSW model is not the only solution possible: more modern solutions, such as Communicating Neighbours may be more appropriate. Variable degrees of textural coarsening will produce CSDs that appear to rotate about a single point. This again reflects closure. Concave up CSDs with no lower size limit are very common. They do not generally have a lognormal or fractal size distribution. They can be produced by mixing of two or more magmas, or crystallisation under several different conditions of undercooling. They can also result from alternations of nucleation and growth followed by textural coarsening. Crystal accumulation and fraction should modify existing CSDs in a predictable manner. An exact solution to this problem has not yet been developed, but simplistic models suggest that CSDs should rotate upwards about the size origin for accumulation and downwards for fractionation. However, clear evidence for such effects has not yet been observed, even in well-layered rocks. There are many igneous systems still to be explored using CSDs. An exiting new domain may be the application of CSDs in experimental petrology.

  18. Mantle Redox Conditions in the North Atlantic Igneous Province

    NASA Astrophysics Data System (ADS)

    Heister, L. E.; Gras, M. A.; Lesher, C. E.

    2004-12-01

    The North Atlantic igneous province (NAIP) has long been viewed as a region of anomalous mantle upwelling related to plume activity, continental rifting, and a heterogeneous mantle source. Prior to continental rifting in the Tertiary, the northern portion of the region was the site of closure of the Iapetus ocean basin. This tectonic event may have contributed to heterogeneities within the upper mantle and altered its oxidation state relative to the ambient mantle. Vanadium has been shown to be a useful indicator of redox conditions due to its multiple valence states (e.g. [1-2]). In mantle minerals, vanadium becomes increasingly incompatible under more oxidizing conditions [3]. Because both scandium and vanadium are moderately incompatible during melting, the Sc/V ratio of primitive basalts can be used to investigate the oxidation state of the mantle [1-3]. We have examined the Sc/V ratios of primitive lavas from the mid-Atlantic ridge (MAR), Iceland, and the East Greenland margin to determine if there are spatial or temporal variations in the oxidation state of the NAIP mantle. The Sc/V ratios for MAR basalts are 0.13-0.20 (GEOROC chemical database); while Icelandic basalts range from 0.10-0.25 with an average of 0.16 (1 σ =0.05). The entire range of Sc/V ratios of the Paleogene East Greenland basalts is 0.07-0.17 with an average of 0.10 (1 σ = 0.05). The Sc/V ratios of Icelandic basalts are similar to MAR basalts, but the East Greenland lavas are distinctly lower than both the MAR and Iceland. The Sc/V ratio also can vary as a function of mean pressure of melting (i.e. spinel versus garnet lherzolite). To test the relative importance of melting systematics, source composition, and oxygen fugacity on the Sc/V systematics for NAIP basalts, we incorporated the oxygen-fugacity-dependent V mineral-melt partitioning data of [3] into the polybaric decompression melting model REEBOX [4]. The best-fit model parameters for the majority of the Iceland and MAR basalts

  19. Zinc electrode in alkaline electrolyte

    SciTech Connect

    McBreen, J.

    1995-12-31

    The zinc electrode in alkaline electrolyte is unusual in that supersaturated zincate solutions can form during discharge and spongy or mossy zinc deposits can form on charge at low overvoltages. The effect of additives on regular pasted ZnO electrodes and calcium zincate electrodes is discussed. The paper also reports on in situ x-ray absorption (XAS) results on mossy zinc deposits.

  20. Petrogenesis of Igneous-Textured Clasts in Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    Santos, A. R.; Agee, C. B.; Humayun, M.; McCubbin, F. M.; Shearer, C. K.

    2016-01-01

    The martian meteorite Northwest Africa 7034 (and pairings) is a breccia that samples a variety of materials from the martian crust. Several previous studies have identified multiple types of igneous-textured clasts within the breccia [1-3], and these clasts have the potential to provide insight into the igneous evolution of Mars. One challenge presented by studying these small rock fragments is the lack of field context for this breccia (i.e., where on Mars it formed), so we do not know how many sources these small rock fragments are derived from or the exact formation his-tory of these sources (i.e., are the sources mantle de-rived melt or melts contaminated by a meteorite impactor on Mars). Our goal in this study is to examine specific igneous-textured clast groups to determine if they are petrogenetically related (i.e., from the same igneous source) and determine more information about their formation history, then use them to derive new insights about the igneous history of Mars. We will focus on the basalt clasts, FTP clasts (named due to their high concentration of iron, titanium, and phosphorous), and mineral fragments described by [1] (Fig. 1). We will examine these materials for evidence of impactor contamination (as proposed for some materials by [2]) or mantle melt derivation. We will also test the petrogenetic models proposed in [1], which are igneous processes that could have occurred regardless of where the melt parental to the clasts was formed. These models include 1) derivation of the FTP clasts from a basalt clast melt through silicate liquid immiscibility (SLI), 2) derivation of the FTP clasts from a basalt clast melt through fractional crystallization, and 3) a lack of petrogenetic relationship between these clast groups. The relationship between the clast groups and the mineral fragments will also be explored.

  1. Geochemical microanalysis: The link between textural and geochemical characterization of igneous rocks

    NASA Astrophysics Data System (ADS)

    Kent, A. J.

    2003-12-01

    In this presentation I will review recent advances in microanalytical techniques that allow us to directly couple textural and geochemical information to the study of igneous rocks, particularly with respect to the analysis of silicate melt inclusions. Textural examination has long been a mainstay of the classification and petrologic study of igneous materials. The advent of the electron microprobe over 50 years ago allowed textural and geochemical observations to be coupled at small spatial scales and directly related to the physical and chemical conditions of formation and subsequent melt evolution. This resulted in a revolution in the petrological investigation and understanding of igneous rocks that continues today. Recent advances in geochemical microanalysis techniques are providing exciting access to new geochemical information at smaller and smaller spatial scales. These are enabling measurement of the abundances, and in some cases isotopic compositions, of a range of elements in correspondingly smaller sample volumes. A case in point is the study of silicate melt inclusions. Although melt inclusions have been recognized and studied for over a century, there has been a recent surge in interest directly tied to development of techniques capable of performing in-situ analysis of trace element and volatile components at small spatial scales. Melt inclusions allow direct sampling of melts present during crystal formation, and are particularly useful for relating crystal textures and compositions to those of their source melts. Chemical compositions of melt inclusions reveal the diversity of igneous compositions present in igneous systems, and may be combined with textural observations to constrain a wide range of igneous processes, including degassing, assimilation, fractional crystallization and mixing.

  2. Cripple Creek and other alkaline-related gold deposits in the Southern Rocky Mountains, USA: Influence of regional tectonics

    USGS Publications Warehouse

    Kelley, K.D.; Ludington, S.

    2002-01-01

    Alkaline-related epithermal vein, breccia, disseminated, skarn, and porphyry gold deposits form a belt in the southern Rocky Mountains along the eastern edge of the North American Cordillera. Alkaline igneous rocks and associated hydrothermal deposits formed at two times. The first was during the Laramide orogeny (about 70-40 Ma), with deposits restricted spatially to the Colorado mineral belt (CMB). Other alkaline igneous rocks and associated gold deposits formed later, during the transition from a compressional to an extensional regime (about 35-27 Ma). These younger rocks and associated deposits are more widespread, following the Rocky Mountain front southward, from Cripple Creek in Colorado through New Mexico. All of these deposits are on the eastern margin of the Cordillera, with voluminous calc-alkaline rocks to the west. The largest deposits in the belt include Cripple Creek and those in the CMB. The most important factor in the formation of all of the gold deposits was the near-surface emplacement of relatively oxidized volatile-rich alkaline magmas. Strontium and lead isotope compositions suggest that the source of the magmas was subduction-modified subcontinental lithosphere. However, Cripple Creek alkaline rocks and older Laramide alkaline rocks in the CMB that were emplaced through hydrously altered LREE-enriched rocks of the Colorado (Yavapai) province have 208Pb/204Pb ratios that suggest these magmas assimilated and mixed with significant amounts of lower crust. The anomalously hot, thick, and light crust beneath Colorado may have been a catalyst for large-scale transfer of volatiles and crustal melting. Increased dissolved H2O (and CO2, F, Cl) of these magmas may have resulted in more productive gold deposits due to more efficient magmatic-hydrothermal systems. High volatile contents may also have promoted Te and V enrichment, explaining the presence of fluorite, roscoelite (vanadium-rich mica) and tellurides in the CMB deposits and Cripple Creek as

  3. Emplacement and Eruption Style in the Franklin Large Igneous Province, Victoria Island, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Bedard, J. H.; Williamson, N.; Dell'Oro, T. A.; Hayes, B.; Hryciuk, M.; Winpenny, A.; Scoates, J. S.; Weis, D. A.; Nabelek, P. I.; Naslund, H. R.; MacDonald, W. D.

    2011-12-01

    The Neoproterozoic Franklin large igneous province preserves up to 1.1 km thickness of basaltic volcanics (Natkusiak Fm.). The Natkusiak volcanics include basal agglutinate and local hyaloclastite breccias and pillows, lensoid or sheet flows, some picritic, and lahar deposits that seem to infill paleo-valleys. The overlying main series lavas are mostly subareal sheet flows and exhibit cycles of upwardly decreasing MgO. Localized vent facies include unconsolidated scoria and bombs, spatter, and fumarolic malachite/zeolite around native Cu veins. Lateral trace element chemical heterogeneity implies eruption through multiple vents with distinct plumbing systems. The underlying exposed 3-4 km of the Shaler Supergroup are dolostones, sandstones, gypsum evaporites and shales, which are riddled with sills (most 20-50m, up to 100m). Sills constitute 50-75% of the section in most places, and belong to two distinct geochemical subtypes. A heterogeneous LREE-enriched facies includes sills with olivine-rich bases. A more homogeneous diabasic subtype has flatter REE patterns and occurs higher in the section. The oft-reported saucer-shaped sill morphology does not occur in the Franklin sills, which tend to be concordant over 10s of km distance. In many places, up-section transgressions appear to be structurally controlled by pre-existing faults that guided magma ascent and may have modulated reactivation and injection of olivine-rich slurries into pre-existing sills. The roof-zones of upward transgressions are injected with arcuate dikes on various scales (1m to 1 km), and are often associated with cataclasites, oxide-sulfide skarns and calc-silicates. These reflect the complexity of melt-driven fracture propagation, varying host ductility, fluctuation of magma pressure, and expulsion of melt and fluids from cooling sills. Some of these intrusions are enriched in sulphide minerals, possibly the result of assimilation of S-rich host rocks.

  4. Flexure and faulting of sedimentary host rocks during growth of igneous domes, Henry Mountains, Utah

    USGS Publications Warehouse

    Jackson, M.D.; Pollard, D.D.

    1990-01-01

    A sequence of sedimentary rocks about 4 km thick was bent, stretched and uplifted during the growth of three igneous domes in the southern Henry Mountains. Mount Holmes, Mount Ellsworth and Mount Hillers are all about 12 km in diameter, but the amplitudes of their domes are about 1.2, 1.85 and 3.0 km, respectively. These mountains record successive stages in the inflation of near-surface diorite intrusions that are probably laccolithic in origin. The host rocks deformed along networks of outcrop-scale faults, or deformation bands, marked by crushed grains, consolidation of the porous sandstone and small displacements of sedimentary beds. Zones of deformation bands oriented parallel to the beds and formation contacts subdivided the overburden into thin mechanical layers that slipped over one another during doming. Measurements of outcrop-scale fault populations at the three mountains reveal a network of faults that strikes at high angles to sedimentary beds which themselves strike tangentially about the domes. These faults have normal and reverse components of slip that accommodated bending and stretching strains within the strata. An early stage of this deformation is displayed at Mount Holmes, where states of stress computed from three fault samples correlate with the theoretical distribution of stresses resulting from bending of thin, circular, elastic plates. Field observations and analysis of frictional driving stresses acting on horizontal planes above an opening-mode dislocation, as well as the paleostress analysis of faulting, indicate that bedding-plane slip and layer flexure were important components of the early deformation. As the amplitude of doming increased, radial and circumferential stretching of the strata and rotation of the older faults in the steepening limbs of the domes increased the complexity of the fault patterns. Steeply-dipping, map-scale faults with dip-slip displacements indicate a late-stage jostling of major blocks over the central

  5. Classification scheme for sedimentary and igneous rocks in Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Mangold, N.; Schmidt, M. E.; Fisk, M. R.; Forni, O.; McLennan, S. M.; Ming, D. W.; Sautter, V.; Sumner, D.; Williams, A. J.; Clegg, S. M.; Cousin, A.; Gasnault, O.; Gellert, R.; Grotzinger, J. P.; Wiens, R. C.

    2017-03-01

    Rocks analyzed by the Curiosity rover in Gale crater include a variety of clastic sedimentary rocks and igneous float rocks transported by fluvial and impact processes. To facilitate the discussion of the range of lithologies, we present in this article a petrological classification framework adapting terrestrial classification schemes to Mars compositions (such as Fe abundances typically higher than for comparable lithologies on Earth), to specific Curiosity observations (such as common alkali-rich rocks), and to the capabilities of the rover instruments. Mineralogy was acquired only locally for a few drilled rocks, and so it does not suffice as a systematic classification tool, in contrast to classical terrestrial rock classification. The core of this classification involves (1) the characterization of rock texture as sedimentary, igneous or undefined according to grain/crystal sizes and shapes using imaging from the ChemCam Remote Micro-Imager (RMI), Mars Hand Lens Imager (MAHLI) and Mastcam instruments, and (2) the assignment of geochemical modifiers based on the abundances of Fe, Si, alkali, and S determined by the Alpha Particle X-ray Spectrometer (APXS) and ChemCam instruments. The aims are to help understand Gale crater geology by highlighting the various categories of rocks analyzed by the rover. Several implications are proposed from the cross-comparisons of rocks of various texture and composition, for instance between in place outcrops and float rocks. All outcrops analyzed by the rover are sedimentary; no igneous outcrops have been observed. However, some igneous rocks are clasts in conglomerates, suggesting that part of them are derived from the crater rim. The compositions of in-place sedimentary rocks contrast significantly with the compositions of igneous float rocks. While some of the differences between sedimentary rocks and igneous floats may be related to physical sorting and diagenesis of the sediments, some of the sedimentary rocks (e

  6. Distribution of Igneous Rocks in Medina and Uvalde Counties, Texas, as Inferred from Aeromagnetic Data

    USGS Publications Warehouse

    Smith, David V.; McDougal, Robert R.; Smith, Bruce D.; Blome, Charles D.

    2008-01-01

    A high-resolution aeromagnetic survey was flown in 2001 over Medina and Uvalde Counties, Texas, as part of a multi-disciplinary investigation of the geohydrologic framework of the Edwards aquifer in south-central Texas. The objective of the survey was to assist in mapping structural features that influence aquifer recharge and ground-water flow. The survey revealed hundreds of magnetic anomalies associated with igneous rocks that had previously been unmapped. This report presents an interpretation of the outcrops and subcrops of igneous rocks, based upon procedures of matched-filtering and potential field modeling.

  7. Modeling the evolution of Sm and Eu abundances during lunar igneous differentiation

    NASA Technical Reports Server (NTRS)

    Weill, D. F.; Mckay, G. A.; Kridelbaugh, S. J.; Grutzeck, M.

    1974-01-01

    The current work presents models for the evolution of europium and samarium abundances during lunar igneous processes. The effect of probable variations in lunar temperature and oxygen fugacity, mineral-liquid distribution coefficients, and the crystallization or melting progression are considered in the model calculations. Changes in the proportions of crystallizing phases strongly influence the evolution of trace element abundances during fractional crystallization, and models must include realistic estimates of the major phase equilibria during crystallization. The results are applied to evaluating the possibility of generating KREEP-rich materials by lunar igneous processes.

  8. Elevation and igneous crater modification on Venus: Implications for magmatic volatile content

    NASA Technical Reports Server (NTRS)

    Wichman, R. W.

    1993-01-01

    Although most impact craters on Venus preserve nearly pristine crater rim and ejecta features, a small number of craters have been identified showing clear evidence of either igneous intrusion emplacement (floor-fracturing) beneath the crater floor or of volcanically embayed exterior ejecta deposits. Since the volcanically embayed craters consistently occur at higher elevations than the identified floor-fractured craters, this report proposes that igneous crater modification on Venus is elevation dependent. This report describes how regional variations in magmatic neutral buoyancy could produce such elevation dependent crater modification and considers the implications for typical magmatic volatile contents on Venus.

  9. A Lithospheric Origin for the Elk Creek Carbonatite Complex, SE Nebraska?

    NASA Astrophysics Data System (ADS)

    Farmer, G. L.

    2015-12-01

    The Elk Creek carbonatite complex in southeastern Nebraska is part of a widespread Cambrian-Ordovician alkali igneous event that affected much of North America during and after the break-up of the Rodinian supercontinent. We conducted whole rock and mineral Nd, Sr, Pb and Hf isotopic analyses of drill cores obtained from this complex in order to assess the source regions of the parental carbonatite magma. Low precision laser ablation U-Pb age determinations from individual zircon grains separated from carbonate-rich "syenites" range from 480 +/- 20 Ma to 540+/- 14 Ma. Whole rock Nd, Sr and Pb isotopic compositions all plot on Cambrian (~550 Ma) isochrons, implying that the carbonatites crystallized from melts with homogeneous radiogenic isotopic compositions. Initial ɛNd and ɛHf are well defined at ~+2 and ~0, respectively, while initial 87Sr/86Sr values are more variable and range from 0.7028 to 0.7058. The contemporaneously emplaced State Line kimberlites in the Front Range of north central Colorado share the same Nd and Sr isotopic compositions imply that sources of these rocks were similar and geographically widespread. Overall, the isotopic compositions are those expected from "Group 1" alkaline igneous rocks, usually interpreted as derivates from the sublithospheric mantle. Cretaceous-Tertiary alkaline rocks in North America generally belong to "Group 1" and may have originated in this fashion (Genet et al., 2014, Earth Planet. Sci. Lett.). An alternative possibility is that the Cambrian-Ordovician carbonatites and kimberlites were derived from underlying, carbonated portions of the lithospheric mantle that formed after the original stabilization of the latter in the Paleoproterozoic. Nd and Hf depleted mantle model ages for the Elk Creek and State Line alkaline rocks range from ~0.8 Ga to ~1.1 Ga and allow the possibility that both sets of intrusive rocks represent melting of mantle metasomatized either during or after the assembly of Rodinia. Widespread

  10. Additional 40Ar- 39Ar dating of the basement and the alkaline volcanism of Gorringe Bank (Atlantic Ocean)

    NASA Astrophysics Data System (ADS)

    Féraud, Gilbert; York, Derek; Mével, Catherine; Cornen, Guy; Hall, Chris M.; Auzende, Jean-Marie

    1986-09-01

    40Ar/ 39Ar step heating analyses are reported for a variety of samples from Gorringe Bank (Atlantic Ocean). Flat age spectra for two primary, igneous hornblendes of Gorringe (corresponding to an age of 143 Ma) show that the K-Ar ages obtained on these samples by Prichard and Mitchell [4] are evidently crystallization and not hybrid ages. This sustains the concept of an initiation age of 140 Ma [4] for Gorringe Bank. No support is found for Carpena's suggestion [7] that the formation of Gorringe Bank began 200 Ma ago. Secondary hornblendes from Ormonde seamount rocks appear to have formed shortly after the initiation of the Bank. Precise plateau ages on samples of two alkaline volcanics from Ormonde correspond to the older limit of the alkaline volcanism suggested by Féraud et al. [3,5].

  11. Geology, alteration and mesothermal Au-Ag-mineralization associated with a volcanic-intrusive complex at Mt. Shamrock-Mt. Ophir, SE Queensland

    NASA Astrophysics Data System (ADS)

    Williams, P. J.

    1991-04-01

    Au-Ag mineralization in the Mt-Shamrock — Mt. Ophir area of SE Queensland is related to a geographically-isolated calc-alkaline igneous centre consisting of high level plutonic and minor intrusions emplaced into the eroded remains of a silicic volcanic ediface and its basement. Mineralization occurs in both the igneous rocks and in the Permian siltstone country rocks and is controlled by a NE-trending structure parallel to Late Triassic lineaments. This structure is unrelated to, and younger than the exposed intrusions. Au-Ag-As-rich, Cu-Mo-poor mineralization occurs in breccias and veinlet networks within pervasively altered rocks characterized by silicification and H (sericite), CO2 (calcite-ankerite), Na (albite), B (tourmaline), and S (pyrite) metasomatism. Secondary mineral compositions suggest that most of this alteration occurred at temperatures between 350 ° and 400 °C. The alteration was complex in detail and characterized by multiple hydrothermal events and space and/or time variations of physico-chemical conditions. Although some of these features are similar to prophyry deposits the chemical character of the alteration and mineralization is not typical of Cu-Mo-Au porphyries and has more in common with tectonometamorphic Au deposits formed at considerably greater depths.

  12. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, David B.; Lao, Guifang

    1998-01-01

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium.

  13. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, D.B.; Lao, G.

    1998-01-06

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium. 3 figs.

  14. Neoproterozoic anorogenic magmatism in the Southern Bahia Alkaline Province of NE Brazil: U-Pb and Pb-Pb ages of the blue sodalite syenites

    NASA Astrophysics Data System (ADS)

    Rosa, Maria de Lourdes da Silva; Conceição, Herbet; Macambira, Moacir José Buenano; Galarza, Marco Antonio; Cunha, Mônica Pringsheim; Menezes, Rita Cunha Leal; Marinho, Moacyr Moura; Filho, Basílio Elesbão da Cruz; Rios, Débora Correia

    2007-08-01

    Blue sodalite syenite is a rare rock, and the Southern Bahia Alkaline Province (SBAP) is the only place in Brazil where economic deposits are found. This province forms part of the Archaean to Paleoproterozoic São Francisco craton, and contains a few batholiths, a large number of stocks and hundreds of dykes. Its southern part lies close to the tectonic contact between the craton and the Neoproterozoic Araçuaí mobile melt. Blue sodalite-bearing syenites are found in almost all the igneous bodies of the SBAP as dykes or pegmatitic masses hosted by nepheline syenite. Economically viable quantities for the production of dimension stones are found only in the Floresta Azul alkaline complex, the Itaju do Colônia and Rio Pardo stocks and the Itarantim batholith.U-Pb ages obtained for titanite from Itaju do Colônia (732 ± 8 Ma) and Rio Pardo (714 ± 8) and Pb-Pb evaporation ages of zircon from Floresta Azul (696 ± 3 Ma) and Itarantim (722 ± 5 Ma). The geochronology of the SBAP shows that the anorogenic alkaline magmatism persisted for at least 58 Ma, demonstrating an extensional tectonic environment in the southern part of the São Francisco craton at this time. The data show that the rift phase which preceded the formation of the Araçuaí orogen was active until at least 700 Ma. The reported ages are similar to those found for the nepheline syenite host bodies, which supports the conclusions of the previous petrologic study demonstrating that blue sodalite is formed during the crystallization of these bodies. Two different processes are involved. In the magmatic process, sodalite occurs as disseminated and interstitial crystals among alkali feldspar crystals, and is associated with calcite and cancrinite formed by destabilization of nepheline. In the metasomatic process, discontinuous bands of sodalite are in sharp contact with nepheline syenite pegmatite, and its crystal aggregates often contain relict textures of nepheline and albite been replaced by sodalite.

  15. Provenance of bentonite layers in the Palaeocene strata of the Central Basin, Svalbard: implications for magmatism and rifting events around the onset of the North Atlantic Igneous Province

    NASA Astrophysics Data System (ADS)

    Jones, Morgan T.; Eliassen, Gauti T.; Shephard, Grace E.; Svensen, Henrik H.; Jochmann, Malte; Friis, Bjarki; Augland, Lars E.; Jerram, Dougal A.; Planke, Sverre

    2016-11-01

    A fold-and-thrust belt developed between Greenland and Svalbard during the Palaeogene, with an associated foreland basin forming in what is now Spitsbergen. This Central Basin is comprised of the Van Mijenfjorden Group, a 2.3 km thick sandstone-shale dominated succession that contains prominent and laterally continuous bentonite layers in the lower formations. These altered tephra layers can be used as stratigraphic markers that connect the basin development with regional explosive volcanism and changes to relative plate motions. We sampled and analysed bentonites from nine borehole cores across the Central Basin. Each layer shows evidence of alteration, with mobile elements such as alkali and alkali earth metals particularly disrupted. However, immobile elements including rare earth elements (REE) and preserved igneous minerals retain a magmatic signature, allowing for comparisons with potential volcanic sources to be made. The majority of bentonites are both evolved and strongly alkaline, with chemical signatures that are much closer to the continental rift events around Ellesmere Island and North Greenland than to the early activity of the North Atlantic Igneous Province (NAIP). There is a clear difference between tephra layers in the mid Palaeocene versus late Palaeocene strata. The early bentonites have a REE signature comparable to the volcanics of the Kap Washington Group exposed in North Greenland. The later bentonites have likely come from volcanic centres in the Nares Strait that are also the source of abundant volcaniclastic sediments in the Judge Daly Promontory, Ellesmere Island. These findings suggest that a mid to late Palaeocene change in locus of volcanic provenance may reflect changes in relative plate motions related to the formation of the West Spitsbergen fold-and-thrust belt and the emplacement of the NAIP. However, the lack of bentonites matching NAIP sources suggests that explosive volcanism was of insufficient magnitude to lead to

  16. The secondary alkaline zinc electrode

    NASA Astrophysics Data System (ADS)

    McLarnon, Frank R.; Cairns, Elton J.

    1991-02-01

    The worldwide studies conducted between 1975 and 1990 with the aim of improving cell lifetimes of secondary alkaline zinc electrodes are overviewed. Attention is given the design features and characteristics of various secondary alkaline zinc cells, including four types of zinc/nickel oxide cell designs (vented static-electrolyte, sealed static-electrolyte, vibrating-electrode, and flowing-electrolyte); two types of zinc/air cells (mechanically rechargeable consolidated-electrode and mechanically rechargeable particulate-electrode); zinc/silver oxide battery; zinc/manganese dioxide cell; and zinc/ferric cyanide battery. Particular consideration is given to recent research in the fields of cell thermodynamics, zinc electrodeposition, zinc electrodissolution, zinc corrosion, electrolyte properties, mathematical and phenomenological models, osmotic pumping, nonuniform current distribution, and cell cycle-life perforamnce.

  17. Development of alkaline fuel cells.

    SciTech Connect

    Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari; Horan, James L.; Caire, Benjamin R.; Ziegler, Zachary C.; Herring, Andrew M.; Yang, Yuan; Zuo, Xiaobing; Robson, Michael H.; Artyushkova, Kateryna; Patterson, Wendy; Atanassov, Plamen Borissov

    2013-09-01

    This project focuses on the development and demonstration of anion exchange membrane (AEM) fuel cells for portable power applications. Novel polymeric anion exchange membranes and ionomers with high chemical stabilities were prepared characterized by researchers at Sandia National Laboratories. Durable, non-precious metal catalysts were prepared by Dr. Plamen Atanassovs research group at the University of New Mexico by utilizing an aerosol-based process to prepare templated nano-structures. Dr. Andy Herrings group at the Colorado School of Mines combined all of these materials to fabricate and test membrane electrode assemblies for single cell testing in a methanol-fueled alkaline system. The highest power density achieved in this study was 54 mW/cm2 which was 90% of the project target and the highest reported power density for a direct methanol alkaline fuel cell.

  18. Siderophile and volatile trace elements in 72255 and 72275. [meteoritic and igneous composition of lunar rocks

    NASA Technical Reports Server (NTRS)

    Morgan, J. W.; Ganapathy, R.; Higuchi, H.; Anders, E.

    1974-01-01

    Of six samples from boulder 1 at Station 2, four contain a unique meteoritic component, which is attributed to the Crisium projectile. The other two samples are meteorite free, igneous rocks: an unusual, alkali- and Ge-rich pigeonitic basalt, and an alkali-poor norite of unexceptional trace element chemistry.

  19. FeO and MgO in plagioclase of lunar anorthosites: Igneous or metamorphic?

    NASA Technical Reports Server (NTRS)

    Phinney, W. C.

    1994-01-01

    The combined evidence from terrestrial anorthosites and experimental laboratory studies strongly implies that lunar anorthosites have been subjected to high-grade metamorphic events that have erased the igneous signatures of FeO and MgO in their plagioclases. Arguments to the contrary have, to this point, been more hopeful than rigorous.

  20. Biological energy from the igneous rock enhances cell growth and enzyme activity.

    PubMed

    Lin, Y; Kuo, H; Chen, C; Kuo, S

    2000-08-01

    Some effects from natural resources might be ignored and unused by humans. Environmental hormesis could be a phenomena necessary to bio-organism existence on earth. Since 1919, radiation and some heavy metal hormesis from the environment were proved in various reports. In this study, igneous rock with very low radioactivity and high ferrous activity was measured by multichannel analyzer and inductively coupled plasma analyzer. The water treated by igneous rock, both directly soaked or indirectly in contact, induced increased activities of glucose oxidase, catalase, peroxidase, and superoxide dismutase. It also increased cell growth of SC-M1, HCT-15, Raji, and fibroblast cell lines. The water after treatment of igneous rock had no change in pH values, but displayed decreased conductivity values. We assume that the igneous rock could transfer energy to water to change the molecular structure or conformation of water cluster, or by radiation hormesis effect could then induce increased enzyme activity and cell growth. It is also possible that the energy from rock may combine radiation hormesis with other transferable biological energy forms to change water cluster conformation.

  1. Potential Igneous Processes Relevant to the Yucca Mountain Repository: Intrusive-Release Scenario

    SciTech Connect

    Apted, M.; Kozak, M.; Kessler, J.

    2006-07-01

    As part of the Department of Energy's (DOE's) license application for the proposed high level radioactive waste and spent nuclear fuel repository proposed for Yucca Mountain, Nevada, the DOE must provide probabilistic dose estimates after repository closure. These estimates must consider all events and processes that are considered reasonably likely to occur, including potential igneous events [1-4]. Current estimates of the probability of a future igneous event intruding through the proposed repository [5] are just high enough that dose consequences must be estimated. Estimates of igneous-event probability and the extent of any radionuclide release resulting from such an event have drawn considerable attention. In general, these estimates have included multiple, compounded conservatisms resulting in significant predicted dose consequences compared to dose consequences from the nominal release scenarios. This new independent study conducted for the Electric Power Research Institute (EPRI) provides a more realistic estimate of the likelihood and magnitude of doses to the public should such a low-probability event occur [6]. Analyses summarized here indicate that, under any reasonable expected conditions for a magmatic intrusion, the contribution to peak dose from such an igneous intrusion event would not affect peak dose estimates over the long term. (authors)

  2. Construction and evolution of igneous bodies: Towards an integrated perspective of crustal magmatism

    NASA Astrophysics Data System (ADS)

    Annen, Catherine; Blundy, Jonathan D.; Leuthold, Julien; Sparks, R. Stephen J.

    2015-08-01

    Field, geochronological and geophysical studies show that many igneous bodies are emplaced incrementally, growing by accretion of successive magma sheets. The existence of melt reservoirs with a size that exceeds one single increment strongly depends on the sheet emplacement rate, whereas the total volumes of magma that accumulate depend on the volumetric magma flux. Integration of geochronological and field data with numerical simulations suggeststhat those rates can vary dramatically over the growth of an igneous body and that magmas accumulate to form melt-rich magma chambers only during episodes of high magma flux. Heat and mass balance considerations and the large volumes of mafic magma required to generate differentiated melts suggest that most crustal differentiation happens in deep hot zones in the lower crust wherein a wide diversity of melts are produced by crystallisation of mafic parents and concomitant partial melting of the crust. Melt composition is further modified during migration, segregation and ascent, and intermediate compositions can be generated when different types of melt mix. Magma fluxes and intrusion geometry play a fundamental role in igneous body evolution. Thus our knowledge of igneous processes depends ultimately on our understanding of the physics that control magma fluxes into the crust, magma emplacement within the crust and magma migration through the crust.

  3. Zircon U-Pb age of the Pescadero felsite: A late Cretaceous igneous event in the forearc, west-central California Coast Ranges

    USGS Publications Warehouse

    Ernst, W.G.; Martens, U.C.; McLaughlin, R.J.; Clark, J.C.; Moore, Diane E.

    2011-01-01

    Weathered felsite is associated with the late Campanian-Maastrichtian Pigeon Point Formation near Pescadero, California. Poorly exposed, its age and correlation are uncertain. Is it part of the Pigeon Point section west of the San Gregorio-Hosgri fault? Does it rest on Nacimiento block basement? Is it dextrally offset from the Oligocene Cambria Felsite, ~185 km to the southeast? Why is a calc-alkaline hypabyssal igneous rock intrusive into the outboard accretionary prism? To address these questions, we analyzed 43 oscillatory-zoned zircon crystals from three incipiently recrystallized pumpellyite ?? prehnite ?? laumontite-bearing Pescadero felsite samples by sensitive high-resolution ion microprobe-reverse geometry (SHRIMPRG) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) techniques. Thirty-three zircons gave late Mesozoic U-Pb ages, with single-grain values ranging from 81 to 167 Ma; ten have pre-Mesozoic, chiefl y Proterozoic ages. A group of the four youngest Pescadero zircons yielded an apparent maximum igneous age of ca. 86-90 Ma. Refl ecting broad age scatter and presence of partly digested sandstone inclusions, we interpret the rest of the zircons (perhaps all) as xenocrysts. Twenty-three zircons were separated and analyzed from two samples of the similar Cambria Felsite, yielding a unimodal 27 Ma U-Pb age. Clearly, the origin of the Upper Oligocene Cambria Felsite is different from that of the Upper Cretaceous Pescadero felsite; these rocks are not correlated, and do not constrain displacement along the San Gregorio-Hosgri fault. Peak ages differ slightly, but relative probability curves for Mesozoic and pre-Mesozoic Pescadero zircons compare well, for example, with abundant U-Pb age data for detrital zircons from Franciscan metaclastic strata ~100 km to the east in the Diablo Range- San Francisco Bay area, San Joaquin Great Valley Group turbidites, Upper Cretaceous Nacimiento block Franciscan strata, and Upper Cretaceous

  4. PROBABILISTIC ANALYSES OF WASTE PACKAGE QUANTITIES IMPACTED BY POTENTIAL IGNEOUS DISRUPTION AT YUCCA MOUNTAIN

    SciTech Connect

    M.G. Wallace

    2005-08-26

    A probabilistic analysis was conducted to estimate ranges for the numbers of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analyses include disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application for the Yucca Mountain Project (YMP). The first scenario, igneous intrusion, investigated the case where one or more igneous dikes intersect the repository. A swarm of dikes was characterized by distributions of length, width, azimuth, and number of dikes and the spacings between them. Through the use in part of a latin hypercube simulator and a modified video game engine, mathematical relationships were built between those parameters and the number of waste packages hit. Corresponding cumulative distribution function curves (CDFs) for the number of waste packages hit under several different scenarios were calculated. Variations in dike thickness ranges, as well as in repository magma bulkhead positions were examined through sensitivity studies. It was assumed that all waste packages in an emplacement drift would be impacted if that drift were intersected by a dike. Over 10,000 individual simulations were performed. Based on these calculations, out of a total of over 11,000 planned waste packages distributed over an area of approximately 5.5 km{sup 2} , the median number of waste packages impacted was roughly 1/10 of the total. Individual cases ranged from 0 waste packages to the entire inventory being impacted. The igneous intrusion analysis involved an explicit characterization of dike-drift intersections, built upon various distributions that reflect the uncertainties associated with the inputs. The second igneous scenario, volcanic eruption (eruptive conduits), considered the effects of conduits formed

  5. Probablistic Analyses of Waste Package Quantities Impacted by Potential Igneous Disruption at Yucca Mountain

    NASA Astrophysics Data System (ADS)

    Wallace, M. G.; Iuzzolina, H.

    2005-12-01

    A probabilistic analysis was conducted to estimate ranges for the numbers of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analysis includes disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application for the Yucca Mountain Project (YMP). The first scenario, igneous intrusion, investigated the case where one or more igneous dikes intersect the repository. A swarm of dikes was characterized by distributions of length, width, azimuth, and number of dikes and the spacings between them. Through the use in part of a latin hypercube simulator and a modified video game engine, mathematical relationships were built between those parameters and the number of waste packages hit. Corresponding cumulative distribution function curves (CDFs) for the number of waste packages hit under several different scenarios were calculated. Variations in dike thickness ranges, as well as in repository magma bulkhead positions were examined through sensitivity studies. It was assumed that all waste packages in an emplacement drift would be impacted if that drift was intersected by a dike. Over 10,000 individual simulations were performed. Based on these calculations, out of a total of over 11,000 planned waste packages distributed over an area of approximately 5.5 km2 , the median number of waste packages impacted was roughly 1/10 of the total. Individual cases ranged from 0 waste packages to the entire inventory being impacted. The igneous intrusion analysis involved an explicit characterization of dike-drift intersections, built upon various distributions that reflect the uncertainties associated with the inputs. The second igneous scenario, volcanic eruption (eruptive conduits), considered the effects of conduits formed in

  6. Continental igneous rock composition: A major control of past global chemical weathering

    PubMed Central

    Bataille, Clément P.; Willis, Amy; Yang, Xiao; Liu, Xiao-Ming

    2017-01-01

    The composition of igneous rocks in the continental crust has changed throughout Earth’s history. However, the impact of these compositional variations on chemical weathering, and by extension on seawater and atmosphere evolution, is largely unknown. We use the strontium isotope ratio in seawater [(87Sr/86Sr)seawater] as a proxy for chemical weathering, and we test the sensitivity of (87Sr/86Sr)seawater variations to the strontium isotopic composition (87Sr/86Sr) in igneous rocks generated through time. We demonstrate that the 87Sr/86Sr ratio in igneous rocks is correlated to the epsilon hafnium (εHf) of their hosted zircon grains, and we use the detrital zircon record to reconstruct the evolution of the 87Sr/86Sr ratio in zircon-bearing igneous rocks. The reconstructed 87Sr/86Sr variations in igneous rocks are strongly correlated with the (87Sr/86Sr)seawater variations over the last 1000 million years, suggesting a direct control of the isotopic composition of silicic magmatism on (87Sr/86Sr)seawater variations. The correlation decreases during several time periods, likely reflecting changes in the chemical weathering rate associated with paleogeographic, climatic, or tectonic events. We argue that for most of the last 1000 million years, the (87Sr/86Sr)seawater variations are responding to changes in the isotopic composition of silicic magmatism rather than to changes in the global chemical weathering rate. We conclude that the (87Sr/86Sr)seawater variations are of limited utility to reconstruct changes in the global chemical weathering rate in deep times. PMID:28345044

  7. Possible Biosphere-Lithosphere Interactions Preserved in Igneous Zircon and Implications for Hadean Earth.

    PubMed

    Trail, Dustin; Tailby, Nicholas D; Sochko, Maggie; Ackerson, Michael R

    2015-07-01

    Granitoids are silicic rocks that make up the majority of the continental crust, but different models arise for the origins of these rocks. One classification scheme defines different granitoid types on the basis of materials involved in the melting/crystallization process. In this end-member case, granitoids may be derived from melting of a preexisting igneous rock, while other granitoids, by contrast, are formed or influenced by melting of buried sedimentary material. In the latter case, assimilated sedimentary material altered by chemical processes occurring at the near surface of Earth-including biological activity-could influence magma chemical properties. Here, we apply a redox-sensitive calibration based on the incorporation of Ce into zircon crystals found in these two rock types, termed sedimentary-type (S-type) and igneous-type (I-type) granitoids. The ∼400 Ma Lachlan Fold Belt rocks of southeastern Australia were chosen for investigation here; these rocks have been a key target used to describe and explore granitoid genesis for close to 50 years. We observe that zircons found in S-type granitoids formed under more reducing conditions than those formed from I-type granitoids from the same terrain. This observation, while reflecting 9 granitoids and 289 analyses of zircons from a region where over 400 different plutons have been identified, is consistent with the incorporation of (reduced) organic matter in the former and highlights one possible manner in which life may modify the composition of igneous minerals. The chemical properties of rocks or igneous minerals may extend the search for ancient biological activity to the earliest period of known igneous activity, which dates back to ∼4.4 billion years ago. If organic matter was incorporated into Hadean sediments that were buried and melted, then these biological remnants could imprint a chemical signature within the subsequent melt and the resulting crystal assemblage, including zircon.

  8. Continental igneous rock composition: A major control of past global chemical weathering.

    PubMed

    Bataille, Clément P; Willis, Amy; Yang, Xiao; Liu, Xiao-Ming

    2017-03-01

    The composition of igneous rocks in the continental crust has changed throughout Earth's history. However, the impact of these compositional variations on chemical weathering, and by extension on seawater and atmosphere evolution, is largely unknown. We use the strontium isotope ratio in seawater [((87)Sr/(86)Sr)seawater] as a proxy for chemical weathering, and we test the sensitivity of ((87)Sr/(86)Sr)seawater variations to the strontium isotopic composition ((87)Sr/(86)Sr) in igneous rocks generated through time. We demonstrate that the (87)Sr/(86)Sr ratio in igneous rocks is correlated to the epsilon hafnium (εHf) of their hosted zircon grains, and we use the detrital zircon record to reconstruct the evolution of the (87)Sr/(86)Sr ratio in zircon-bearing igneous rocks. The reconstructed (87)Sr/(86)Sr variations in igneous rocks are strongly correlated with the ((87)Sr/(86)Sr)seawater variations over the last 1000 million years, suggesting a direct control of the isotopic composition of silicic magmatism on ((87)Sr/(86)Sr)seawater variations. The correlation decreases during several time periods, likely reflecting changes in the chemical weathering rate associated with paleogeographic, climatic, or tectonic events. We argue that for most of the last 1000 million years, the ((87)Sr/(86)Sr)seawater variations are responding to changes in the isotopic composition of silicic magmatism rather than to changes in the global chemical weathering rate. We conclude that the ((87)Sr/(86)Sr)seawater variations are of limited utility to reconstruct changes in the global chemical weathering rate in deep times.

  9. Catalytic activity of ruthenium(III) on the oxidation of an anticholinergic drug-atropine sulfate monohydrate by copper(III) periodate complex in aqueous alkaline medium - decarboxylation and free radical mechanism.

    PubMed

    Byadagi, Kirthi S; Nandibewoor, Sharanappa T; Chimatadar, Shivamurti A

    2013-01-01

    Atropine sulfate monohydrate (ASM) is an anticholinergic drug, having a wide spectrum of activity. Hence, the kinetics of oxidation of ASM by diperiodatocuperate (DPC) in the presence of micro (10-6) amounts of Ru(III) catalyst has been investigated spectrophotometrically in aqueous alkaline medium at I = 0.50 mol dm-3. The reaction between DPC and ASM exhibits 1:2 stoichiometry (ASM:DPC) i. e., one mole of ASM require two moles of DPC to give products. The main oxidation products were confirmed by spectral studies. The reaction is first order with respect to [DPC] and [Ru(III)], while the order with respect to [ASM] and [OH-] was less than unity. The rates decreased with increase in periodate concentration. The reaction rates revealed that Ru(III) catalyzed reaction was about seven-fold faster than the uncatalyzed reaction. The catalytic constant (KC) was also determined at different temperatures. A plausible mechanism is proposed. The activation parameters with respect to slow step of the mechanism were calculated and the thermodynamic quantities were also determined. Kinetic experiments suggest that [Cu(H2IO6)(H2O)2] is the reactive Cu(III) species and [Ru(H2O)5OH]2+ is the reactive Ru(III) species.

  10. Complex igneous processes and the formation of the primitive lunar crustal rocks

    NASA Technical Reports Server (NTRS)

    Longhi, J.; Boudreau, A. E.

    1979-01-01

    Crystallization of a magma ocean with initial chondritic Ca/Al and REE ratios such as proposed by Taylor and Bence (TB, 1975), is capable of producing the suite of primitive crustal rocks if the magma ocean underwent locally extensive assimilation and mixing in its upper layers as preliminary steps in formation of an anorthositic crust. Lunar anorthosites were the earliest permanent crustal rocks to form the result of multiple cycles of suspension and assimilation of plagioclase in liquids fractionating olivine and pyroxene. There may be two series of Mg-rich cumulate rocks: one which developed as a result of the equilibration of anorthositic crust with the magma ocean; the other which formed in the later stages of the magma ocean during an epoch of magma mixing and ilmenite crystallization. This second series may be related to KREEP genesis. It is noted that crystallization of the magma ocean had two components: a low pressure component which produced a highly fractionated and heterogeneous crust growing downward and a high pressure component which filled in the ocean from the bottom up, mostly with olivine and low-Ca pyroxene.

  11. Igneous layering in the peralkaline intrusions ,Kola Peninsula :leading role of gravitational differentiation

    NASA Astrophysics Data System (ADS)

    Kogarko, L. N..

    2012-04-01

    In the center of Kola Peninsula there are two large layered intrusions of agpaitic nepheline syenites - Khibina and Lovozero. . The Khibina alkaline massif (Kola Peninsula,Russia) hosts the world's largest and economically most important apatite deposit. The Khibina massif is a complex multiphase body built up from a number of ring-like and conical intrusions. The apatite bearing intrusion is ring-like and is represented by a layered body of ijolitic composition with a thickness of about 1 - 2 km. The upper zone is represented by different types of apatite ores. These rocks consist of 60-90% euhedral very small (tenths of mm)apatite crystals. The lower zone has mostly ijolitic composition. The lower zone grades into underlying massive urtite consisting of 75-90% large (several mm) euhedral nepheline. Our experimental studies of systems with apatite demonstrated the near-eutectic nature of the apatite-bearing intrusion, resulting in practically simultaneous crystallization of nepheline, apatite and pyroxene. The mathematical model of the formation of the layered apatite-bearing intrusion based on the processes of sedimentation under the conditions of steady state convection taking account of crystal sizes is proposed. Under the conditions of steady-state convection large crystals of nepheline continuously had been settling forming massive underlying urtite whereas smaller crystals of pyroxenes, nepheline and apatite had been stirred in the convecting melt. During the cooling the intensity of convection decreased causing a settling of smaller crystals of nepheline and pyroxene and later very small crystalls of apatite in the upper part of alkaline magma chamber. The Lovozero massif, the largest of the Globe layered peralkaline intrusion, comprises super-large rare-metal (Nb, Ta, REE) deposit. The main ore mineral is loparite (Na, Ce, Ca)2 (Ti, Nb)2O6 which was mined during many years. The composition of cumulus loparite changed systematically upward through the

  12. Petrology of igneous clasts in Northwest Africa 7034: Implications for the petrologic diversity of the martian crust

    NASA Astrophysics Data System (ADS)

    Santos, Alison R.; Agee, Carl B.; McCubbin, Francis M.; Shearer, Charles K.; Burger, Paul V.; Tartèse, Romain; Anand, Mahesh

    2015-05-01

    The martian meteorite Northwest Africa (NWA) 7034 was examined both petrographically and geochemically using several micro-beam techniques including electron probe microanalysis and secondary ion mass spectrometry. We have identified various clast types of igneous, sedimentary, and impact origin that occur within the breccia, and we define a classification scheme for these materials based on our observations, although our primary focus here is on the petrology of the igneous clasts. A number of different igneous clasts are present in this meteorite, and our study revealed the presence of at least four different igneous lithologies (basalt, basaltic andesite, trachyandesite, and an Fe, Ti, and P (FTP) rich lithology). These lithologies do not appear to be related by simple igneous processes such as fractional crystallization, indicating NWA 7034 is a polymict breccia that contains samples from several different igneous sources. The basalt lithologies are a good match for measured rock compositions from the martian surface, however more exotic lithologies (e.g., trachyandesite and FTP lithologies) show this meteorite contains previously unsampled rock types from Mars. These new rock types provide evidence for a much greater variety of igneous rocks within the martian crust than previously revealed by martian meteorites, and supports recent rover observations of lithologic diversity across the martian surface. Furthermore, the ancient ages for the lithologic components in NWA 7034 indicate Mars developed this lithologic diversity in the early stages of crust formation.

  13. Alkaline fuel cell performance investigation

    NASA Technical Reports Server (NTRS)

    Martin, R. E.; Manzo, M. A.

    1988-01-01

    An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more that two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

  14. Diffusion effects on oxygen isotope temperatures of slowly cooled igneous and metamorphic rocks

    NASA Astrophysics Data System (ADS)

    Giletti, Bruno J.

    1986-03-01

    Recently obtained data on oxygen diffusion in feldspars, quartz, and hornblende permit the prediction of the apparent 18O 16O temperatures that would be measured in a rock that consisted only of those three minerals, and cooled slowly from high temperature. The computed temperatures would be based on the differences in the 18O 16O ratios between coexisting pairs of minerals. The present calculation takes into account the diffusion rates for oxygen as a function of temperature, the cooling rate of the rock, the mineral grain sizes, and the mode of the rock. For mineral grains 1 mm in radius, and a cooling rate of 10°C/m.y., the minimum difference in apparent temperature between quartz-feldspar and feldspar-hornblende pairs will be 115°C, despite the assumption of a normal, uneventful, slow cooling history to room temperature. Further, the apparent quartz-hornblende temperature will range over 30°C (590-620°C) depending on the mode of the rock. For a cooling rate of 1000°C/m.y., the apparent difference in temperature can be as much as 400°C. Consequently, consistency in temperatures obtained by oxygen isotope analysis should not be expected in most high-grade metamorphic rocks or igneous rocks which are cooled slowly. Departures from the pattern of temperatures obtained in this model would imply a very rapid quench from high temperature, or a complex history for the rock. For some minerals, including hornblende, the relation between temperature and the equilibrium fractionation of oxygen isotopes between coexisting phases has been derived from observed relations in natural specimens. The choice of the specimens used for such calibrations needs to be re-evaluated in light of these findings. This may result in a change in the equilibrium equation constants. An example from the literature, the San Jose tonalite, Baja California, Mexico, was modelled and yields δ 18O concentrations in the minerals that correspond closely with the measured values. This suggests

  15. Assessing the volcanic styles of the North Atlantic Igneous Province and their potential implications for the PETM

    NASA Astrophysics Data System (ADS)

    Jerram, Dougal; Reynolds, Peter; Jones, Morgan; Svensen, Henrik; Planke, Sverre; Millett, John; Galland, Olivier; Angkasa, Syahreza; Schofield, Nick; Howell, John

    2016-04-01

    In order to understand the role that large igneous provinces play in changing climatic conditions, it is important to constrain the different styles of volcanism and their volumes, both temporally and spatially. Regional variations in palaeo-environment as well as different volcanic materials (basic-acidic) can all have effects on the eruption styles, and determine whether eruptions effectively release gases into the atmosphere and hydrosphere. The North Atlantic Igneous Province (NAIP) covers a vast area as well as a significant time span, having formed at 60-55 Ma. Importantly, its' formation is implicated in the climatic perturbations at the Palaeocene-Eocene Thermal Maximum (PETM). The products of volcanism in the NAIP range from lava flows and hyaloclastites to more explosive tephra forming eruptions from both basaltic and more evolved eruptions. The explosive end member styles of both mafic and felsic volcanism also produce ash beds in the rock record at key times. Hydrothermal vent structures which are predominantly related with the emplacement of large (>1000 km3) intrusions into the subvolcanic basins in the NAIP are another style of eruption, where climate-forcing gases can be transferred into the atmosphere and hydrosphere. In this case, the types and volumes of gas produced by intrusions is heavily dependent on the host-rock sediment properties that they intrude through. The distribution of vent structures can be shown to be widespread on both the Norwegian and the Greenland margins of the NAIP. In this overview we assess the main eruption styles, deposits and their distribution within the NAIP using mapped examples from offshore seismic data as well as outcrop analogues, highlighting the variability of these structures and their deposits. As the availability of 3D data from offshore and onshore increases, the full nature of the volcanic stratigraphy from the subvolcanic intrusive complexes, through the main eruption cycles into the piercing vent

  16. The catalytic properties of alkaline phosphatases under various conditions

    NASA Astrophysics Data System (ADS)

    Atyaksheva, L. F.; Chukhrai, E. S.; Poltorak, O. M.

    2008-11-01

    A comparative study was performed to examine the catalytic properties of alkaline phosphatases from bacteria Escherichia coli and bovine and chicken intestines. The activity of enzyme dimers and tetramers was determined. The activity of the dimer was three or four times higher than that of the tetramer. The maximum activity and affinity for 4-nitrophenylphosphate was observed for the bacterial alkaline phosphatase ( K M = 1.7 × 10-5 M, V max = 1800 μmol/(min mg of protein) for dimers and V max = 420 μmol/(min mg of protein) for tetramers). The Michaelis constants were equal for two animal phosphatases in various buffer media (pH 8.5) ((3.5 ± 0.2) × 10-4 M). Five buffer systems were investigated: tris, carbonate, hepes, borate, and glycine buffers, and the lowest catalytic activity of alkaline phosphatases at equal pH was observed in the borate buffer (for enzyme from bovine intestine, V max = 80 μmol/(min mg of protein)). Cu2+ cations formed a complex with tris-(oxymethyl)-aminomethane ( tris-HCl buffer) and inhibited the intestine alkaline phosphatases by a noncompetitive mechanism.

  17. Polytopic vector analysis in igneous petrology: Application to lunar petrogenesis

    NASA Technical Reports Server (NTRS)

    Shervais, John W.; Ehrlich, R.

    1993-01-01

    Lunar samples represent a heterogeneous assemblage of rocks with complex inter-relationships that are difficult to decipher using standard petrogenetic approaches. These inter-relationships reflect several distinct petrogenetic trends as well as thermomechanical mixing of distinct components. Additional complications arise from the unequal quality of chemical analyses and from the fact that many samples (e.g., breccia clasts) are too small to be representative of the system from which they derived. Polytopic vector analysis (PVA) is a multi-variate procedure used as a tool for exploratory data analysis. PVA allows the analyst to classify samples and clarifies relationships among heterogenous samples with complex petrogenetic histories. It differs from orthogonal factor analysis in that it uses non-orthogonal multivariate sample vectors to extract sample endmember compositions. The output from a Q-mode (sample based) factor analysis is the initial step in PVA. The Q-mode analysis, using criteria established by Miesch and Klovan and Miesch, is used to determine the number of endmembers in the data system. The second step involves determination of endmembers and mixing proportions with all output expressed in the same geochemical variable as the input. The composition of endmembers is derived by analysis of the variability of the data set. Endmembers need not be present in the data set, nor is it necessary for their composition to be known a priori. A set of any endmembers defines a 'polytope' or classification figure (triangle for a three component system, tetrahedron for a four component system, a 'five-tope' in four dimensions for five component system, et cetera).

  18. Influence of Landscape Morphology and Vegetation Cover on the Sampling of Mixed Igneous Bodies

    NASA Astrophysics Data System (ADS)

    Perugini, Diego; Petrelli, Maurizio; Poli, Giampiero

    2010-05-01

    A plethora of evidence indicates that magma mixing processes can take place at any evolutionary stage of magmatic systems and that they are extremely common in both plutonic and volcanic environments (e.g. Bateman, 1995). Furthermore, recent studies have shown that the magma mixing process is governed by chaotic dynamics whose evolution in space and time generates complex compositional patterns that can span several length scales producing fractal domains (e.g. Perugini et al., 2003). The fact that magma mixing processes can produce igneous bodies exhibiting a large compositional complexity brings up the key question about the potential pitfalls that may be associated with the sampling of these systems for petrological studies. In particular, since commonly only exiguous portions of the whole magmatic system are available as outcrops for sampling, it is important to address the point whether the sampling may be considered representative of the complexity of the magmatic system. We attempt to address this crucial point by performing numerical simulations of chaotic magma mixing processes in 3D. The numerical system used in the simulations is the so-called ABC (Arnold-Beltrami-Childress) flow (e.g. Galluccio and Vulpiani, 1994), which is able to generate the contemporaneous occurrence of chaotic and regular streamlines in which the mixing efficiency is differently modulated. This numerical system has already been successfully utilized as a kinematic template to reproduce magma mixing structures observed on natural outcrops (Perugini et al., 2007). The best conditions for sampling are evaluated considering different landscape morphologies and percentages of vegetation cover. In particular, synthetic landscapes with different degree of roughness are numerically reproduced using the Random Mid-point Displacement Method (RMDM; e.g. Fournier et al., 1982) in two dimensions and superimposed to the compositional fields generated by the magma mixing simulation. Vegetation

  19. Alkaline detergent recycling via ultrafiltration

    SciTech Connect

    Steffani, C.; Meltzer, M.

    1995-06-01

    The metal finishing industry uses alkaline cleaners and detergents to remove oils and dirt from manufactured parts, often before they are painted or plated. The use of these cleaners has grown because environmental regulations are phasing out ozone depleting substances and placing restrictions on the use and disposal of many hazardous solvents. Lawrence Livermore National Laboratory is examining ultrafiltration as a cleaning approach that reclaims the cleaning solutions and minimizes wastes. The ultrafiltration membrane is made from sheets of polymerized organic film. The sheets are rolled onto a supporting frame and installed in a tube. Spent cleaning solution is pumped into a filter chamber and filtered through the membrane that captures oils and dirt and allows water and detergent to pass. The membrane is monitored and when pressure builds from oil and dirt, an automatic system cleans the surface to maintain solution flow and filtration quality. The results show that the ultrafiltration does not disturb the detergent concentration or alkalinity but removed almost all the oils and dirt leaving the solution in condition to be reused.

  20. Analysis and Discrimination of Sedimentary, Metamorphic, and Igneous Rocks Using Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rai, Ab. Kr.; Maurya, G. S.; Kumar, R.; Pathak, A. K.; Pati, J. K.; Rai, Aw. K.

    2017-01-01

    This study deals with the analysis of rocks using laser-induced breakdown spectroscopy (LIBS) coupled with principal component analysis. The spectra of sedimentary, metamorphic, and igneous rock samples were recorded in the 200-900 nm spectral range. The atomic lines of elements such as Si, Ca, Mg, Fe, Na, and K along with lighter elements, namely C, H, N, and O, were observed in these spectra. Multivariate analysis in combination with LIBS was used to classify the samples. For principal component analysis, a 12 × 5849 data matrix was formed using the results of LIBS. The plot of the analysis revealed similarities between the sedimentary and metamorphic rock samples compared with the igneous rock sample. Thus, the present study demonstrates that LIBS coupled with principal component analysis can become an important tool for rapid classification and in-situ discrimination of rock samples.

  1. Alkaline and alkaline earth metal phosphate halides and phosphors

    DOEpatents

    Lyons, Robert Joseph; Setlur, Anant Achyut; Cleaver, Robert John

    2012-11-13

    Compounds, phosphor materials and apparatus related to nacaphite family of materials are presented. Potassium and rubidium based nacaphite family compounds and phosphors designed by doping divalent rare earth elements in the sites of alkaline earth metals in the nacaphite material families are descried. An apparatus comprising the phosphors based on the nacaphite family materials are presented herein. The compounds presented is of formula A.sub.2B.sub.1-yR.sub.yPO.sub.4X where the elements A, B, R, X and suffix y are defined such that A is potassium, rubidium, or a combination of potassium and rubidium and B is calcium, strontium, barium, or a combination of any of calcium, strontium and barium. X is fluorine, chlorine, or a combination of fluorine and chlorine, R is europium, samarium, ytterbium, or a combination of any of europium, samarium, and ytterbium, and y ranges from 0 to about 0.1.

  2. Igneous lithologies on asteroid (4) Vesta mapped using gamma-ray and neutron data

    NASA Astrophysics Data System (ADS)

    Beck, Andrew W.; Lawrence, David J.; Peplowski, Patrick N.; Viviano-Beck, Christina E.; Prettyman, Thomas H.; McCoy, Timothy J.; McSween, Harry Y.; Yamashita, Naoyuki

    2017-04-01

    We use data collected by the Dawn Gamma-Ray and Neutron Detector (GRaND) at Vesta to map compositions corresponding to nearly pure igneous lithologies in the howardite, eucrite, diogenite (HED) meteorite clan (samples likely from Vesta). At the ∼300-km spatial scale of GRaND measurements, basaltic eucrite occurs on only 3% of the surface, whereas cumulate eucrite and orthopyroxenitic diogenite are not detected. The basaltic eucrite region is generally coincident with an area of the surface with thick regolith, elevated H, and moderate crater density, and may represent the best compositional sample of primordial vestan crust. We observe an absence of pure orthopyroxenitic diogenite terrains in the Rheasilvia basin and its ejecta, an observation corroborated by VIR (0.1%), which suggests the south-polar crust was a polymict mixture of igneous lithologies (howardite) at the time of the Rheasilvia impact, or was a thick basaltic eucrite crust with heterogeneously distributed orthopyroxenitic diogenite plutons. The most dominant igneous composition detected (11% of the surface) corresponds to one of the least-abundant igneous lithologies in the HED meteorite collection, the Yamato Type B diogenites (plagioclase-bearing pyroxenites). The distribution of Type B diogenite is spatially correlated with post-Rheasilvia craters in the north-polar region that are in close proximity to the Rheasilvia basin antipode. This suggests that north-polar Type B plutonism may have been associated with the Rheasilvia impact event. We propose that this was either through 1) uplift of pre-existing plutons at the antipode through focusing of Rheasilvia impact stress, or 2) Rheasilvia impact antipodal crustal melting, creating magmas that underwent fractionation to produce Type B plutons.

  3. Classification and Geochemical Characterization of Igneous Rocks: Southern Part of Chihuahua City, Mexico

    NASA Astrophysics Data System (ADS)

    Fontes, I. D.; Espejel-Garcia, V. V.; Villalobos-Aragon, A.

    2013-05-01

    Chihuahua City is the capital of the state with the same name, located in northern Mexico. The city was established near the Chuviscar River, but in the last decades it has been extended to the nearby areas (mountains), with volcanic (rhyolitic tuffs), and sedimentary rocks (limestone). The study area includes areas in the south part of Chihuahua City, where we can still find unbuilt lands and it is possible to appreciate outcrops of igneous rocks. This project includes 5 study spots, which are located about 9 km. far from the south extreme of the city. This research is developed in order to complement the geological information in this area, as there is no is detailed record of it. In the geological map H13-10 (SGM, 1997), it is said that the urban area is covered by Quaternary conglomerates, while exploring the region we have located several igneous rocks outcrops. In three of the sampling points, dark colored intrusive igneous rocks with large crystals appear in blocks without noticeable fractures. While in the other two sampling points, highly fractured blocks of pink aphanitic igneous rocks, showing traces of pyrolusite were observed. The petrographic study shows the two different textures that classify these rocks as extrusive (aphanitic) or intrusive (phaneritic), both with quartz and feldspars being the dominant minerals. Geochemical analyses confirm the felsic composition of the rocks, varying form trachytes to rhyolites. The trace element results show high contents of Sr, Ba, V, Rb, and Zr in trachytic compositions, while there are high concentrations of Mn, W, Rb and Co for rhyolitic compositions.

  4. Termination time of peak decratonization in North China: Geochemical evidence from mafic igneous rocks

    NASA Astrophysics Data System (ADS)

    Dai, Li-Qun; Zheng, Yong-Fei; Zhao, Zi-Fu

    2016-01-01

    Geophysical and petrological data indicate destruction of the cratonic lithosphere in North China in the Mesozoic, resulting in replacement of the ancient subcontinental lithospheric mantle (SCLM) by the juvenile SCLM. However, it remains to be answered when the craton destruction would have been terminated in the Mesozoic. This question is resolved by studying the two types of mafic igneous rocks with contrasting geochemical compositions from North China. The first type of mafic igneous rock shows arc-like trace element distribution patterns and enriched radiogenic Sr-Nd isotope compositions, with emplacement ages spanning from the Triassic to Early Cretaceous. The mafic magmatism is absent in a period from 200 Ma to 135 Ma, recording the thinning of cratonic lithosphere due to the westward flat subduction of the Paleo-Pacific slab beneath the North China Craton. In contrast, the second type of mafic igneous rocks exhibits oceanic island basalts (OIB)-like trace element distribution patterns and relatively depleted radiogenic Sr-Nd isotope compositions, with emplacement ages spanning from the Early Cretaceous to Cenozoic. Zircon U-Pb dating yields an age of 121 Ma for the geochemical transformation between the two types of mafic igneous rocks. This age marks a dramatic demarcation in the composition of their mantle sources. As such, the nature of mantle lithosphere in North China was changed from the ancient SCLM to the juvenile SCLM at 121 Ma. Thus, this age not only signifies the tectonic transition from the enriched mantle to the depleted mantle in the Early Cretaceous, but also dates the termination of peak decratonization in North China. Therefore, the craton destruction in the Early Cretaceous is temporally and spatially associated with the dramatic changes in the geochemical composition of mantle lithosphere.

  5. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    NASA Technical Reports Server (NTRS)

    Dewit, M. J.

    1986-01-01

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  6. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    NASA Astrophysics Data System (ADS)

    Dewit, M. J.

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  7. Primary uranium sources for sedimentary-hosted uranium deposits in NE China: insight from basement igneous rocks of the Erlian Basin

    NASA Astrophysics Data System (ADS)

    Bonnetti, Christophe; Cuney, Michel; Bourlange, Sylvain; Deloule, Etienne; Poujol, Marc; Liu, Xiaodong; Peng, Yunbiao; Yang, Jianxing

    2017-03-01

    Carboniferous-Permian, Triassic and Jurassic igneous basement rocks around the Erlian Basin in northeast China have been investigated through detailed mineralogical, whole-rock geochemistry, geochronological data and Sm-Nd isotope studies. Carboniferous-Permian biotite granites and volcanic rocks belong to a calc-alkaline association and were emplaced during the Late Carboniferous-Early Permian (313 ± 1-286 ± 2 Ma). These rocks are characterised by positive ɛNd( t) (3.3-5.3) and fairly young T DM model ages (485-726 Ma), suggesting a dominant derivation from partial melting of earlier emplaced juvenile source rocks. Triassic biotite granites belong to a high-K calc-alkaline association and were emplaced during the Middle Triassic (243 ± 3-233 ± 2 Ma). Their negative ɛNd( t) (-2 to -0.1) and higher T DM model ages (703-893 Ma) suggest a contribution from Precambrian crust during the magma generation processes, leading to a strong enrichment in K and incompatible elements such as Th and U. Highly fractionated magmas crystallised in U-rich biotite (up to 21 ppm U) and two-mica granites. In biotite granite, the major U-bearing minerals are uranothorite and allanite. They are strongly metamict and the major part of their uranium (90 %) has been released from the mineral structure and was available for leaching. Mass balance calculations show that the Triassic biotite granites may have, at least, liberated ˜14,000 t U/km3 and thus correspond to a major primary uranium source for the U deposits hosted in the Erlian Basin.

  8. Ages of igneous and hydrothermal events in the Round Mountain and Manhattan gold districts, Nye County, Nevada.

    USGS Publications Warehouse

    Shawe, D.R.; Marvin, R.F.; Andriessen, P.A.M.; Mehnert, H.H.; Merritt, V.M.

    1986-01-01

    Isotopic age determinations of rocks and minerals separated from them are applied to refining and correlating the geological history of igneous and mineralizing events in a part of the Basin and Range province. -G.J.N.

  9. Strength/Brittleness Classification of Igneous Intact Rocks Based on Basic Physical and Dynamic Properties

    NASA Astrophysics Data System (ADS)

    Aligholi, Saeed; Lashkaripour, Gholam Reza; Ghafoori, Mohammad

    2017-01-01

    This paper sheds further light on the fundamental relationships between simple methods, rock strength, and brittleness of igneous rocks. In particular, the relationship between mechanical (point load strength index I s(50) and brittleness value S 20), basic physical (dry density and porosity), and dynamic properties (P-wave velocity and Schmidt rebound values) for a wide range of Iranian igneous rocks is investigated. First, 30 statistical models (including simple and multiple linear regression analyses) were built to identify the relationships between mechanical properties and simple methods. The results imply that rocks with different Schmidt hardness (SH) rebound values have different physicomechanical properties or relations. Second, using these results, it was proved that dry density, P-wave velocity, and SH rebound value provide a fine complement to mechanical properties classification of rock materials. Further, a detailed investigation was conducted on the relationships between mechanical and simple tests, which are established with limited ranges of P-wave velocity and dry density. The results show that strength values decrease with the SH rebound value. In addition, there is a systematic trend between dry density, P-wave velocity, rebound hardness, and brittleness value of the studied rocks, and rocks with medium hardness have a higher brittleness value. Finally, a strength classification chart and a brittleness classification table are presented, providing reliable and low-cost methods for the classification of igneous rocks.

  10. Classification Scheme for Diverse Sedimentary and Igneous Rocks Encountered by MSL in Gale Crater

    NASA Technical Reports Server (NTRS)

    Schmidt, M. E.; Mangold, N.; Fisk, M.; Forni, O.; McLennan, S.; Ming, D. W.; Sumner, D.; Sautter, V.; Williams, A. J.; Gellert, R.

    2015-01-01

    The Curiosity Rover landed in a lithologically and geochemically diverse region of Mars. We present a recommended rock classification framework based on terrestrial schemes, and adapted for the imaging and analytical capabilities of MSL as well as for rock types distinctive to Mars (e.g., high Fe sediments). After interpreting rock origin from textures, i.e., sedimentary (clastic, bedded), igneous (porphyritic, glassy), or unknown, the overall classification procedure (Fig 1) involves: (1) the characterization of rock type according to grain size and texture; (2) the assignment of geochemical modifiers according to Figs 3 and 4; and if applicable, in depth study of (3) mineralogy and (4) geologic/stratigraphic context. Sedimentary rock types are assigned by measuring grains in the best available resolution image (Table 1) and classifying according to the coarsest resolvable grains as conglomerate/breccia, (coarse, medium, or fine) sandstone, silt-stone, or mudstone. If grains are not resolvable in MAHLI images, grains in the rock are assumed to be silt sized or smaller than surface dust particles. Rocks with low color contrast contrast between grains (e.g., Dismal Lakes, sol 304) are classified according to minimum size of apparent grains from surface roughness or shadows outlining apparent grains. Igneous rocks are described as intrusive or extrusive depending on crystal size and fabric. Igneous textures may be described as granular, porphyritic, phaneritic, aphyric, or glassy depending on crystal size. Further descriptors may include terms such as vesicular or cumulate textures.

  11. Voluminous silicic eruptions during late Permian Emeishan igneous province and link to climate cooling

    NASA Astrophysics Data System (ADS)

    Yang, Jianghai; Cawood, Peter A.; Du, Yuansheng

    2015-12-01

    Silicic eruptive units can constitute a substantive component in flood-basalts-dominated large igneous provinces, but usually constitute only a small proportion of the preserved volume due to poor preservation. Thus, their environmental impact can be underestimated or ignored. Establishing the original volume and potential climate-sensitive gas emissions of silicic eruptions is generally lacking for most large igneous provinces. We present a case study for the ∼260 Ma Emeishan province, where silicic volcanic rocks are a very minor component of the preserved rock archive due to extensive erosion during the Late Permian. Modal and geochemical data from Late Permian sandstones derived from the province suggest that silicic volcanic rocks constituted some ∼30% by volume of the total eroded Emeishan volcanic source rocks. This volume corresponds to > 3 ×104 km3 on the basis of two independent estimate methods. Detrital zircon trace element and Hf isotopic data require the silicic source rocks to be formed mainly by fractional crystallization from associated basaltic magmas. Based on experimental and theoretical calculations, these basalt-derived ∼104 km3 silicic eruptions released ∼1017 g sulfur gases into the higher atmosphere and contribute to the contemporaneous climate cooling at the Capitanian-Wuchiapingian transition (∼260 Ma). This study highlights the potentially important impact on climate of silicic eruptions associated with large igneous province volcanism.

  12. Igpet software for modeling igneous processes: examples of application using the open educational version

    NASA Astrophysics Data System (ADS)

    Carr, Michael J.; Gazel, Esteban

    2016-09-01

    We provide here an open version of Igpet software, called t-Igpet to emphasize its application for teaching and research in forward modeling of igneous geochemistry. There are three programs, a norm utility, a petrologic mixing program using least squares and Igpet, a graphics program that includes many forms of numerical modeling. Igpet is a multifaceted tool that provides the following basic capabilities: igneous rock identification using the IUGS (International Union of Geological Sciences) classification and several supplementary diagrams; tectonic discrimination diagrams; pseudo-quaternary projections; least squares fitting of lines, polynomials and hyperbolae; magma mixing using two endmembers, histograms, x-y plots, ternary plots and spider-diagrams. The advanced capabilities of Igpet are multi-element mixing and magma evolution modeling. Mixing models are particularly useful for understanding the isotopic variations in rock suites that evolved by mixing different sources. The important melting models include, batch melting, fractional melting and aggregated fractional melting. Crystallization models include equilibrium and fractional crystallization and AFC (assimilation and fractional crystallization). Theses, reports and proposals concerning igneous petrology are improved by numerical modeling. For reviewed publications some elements of modeling are practically a requirement. Our intention in providing this software is to facilitate improved communication and lower entry barriers to research, especially for students.

  13. Rubidium-87/strontium-87 age of juvinas basaltic achondrite and early igneous activity in the solar system.

    PubMed

    Allégre, C J; Birck, J L; Fourcade, S; Semet, M P

    1975-02-07

    A (4.60+/-0.07)x10(9) year internal isochron has been drawn for the achondrite Juvinas by the rubidium-87/strontium-87 method. Earlier petrographic investigation of achondrites supplemented by a new ion microprobe study of Juvinas strongly suggest an igneous origin for this class of meteorites. The results thus indicate that igneous activity may have rapidly followed the formation of the achondrites' parent body 4.6x10(9) years ago.

  14. Early-Middle Paleozoic subduction-collision history of the south-eastern Central Asian Orogenic Belt: Evidence from igneous and metasedimentary rocks of central Jilin Province, NE China

    NASA Astrophysics Data System (ADS)

    Pei, Fu-Ping; Zhang, Ying; Wang, Zhi-Wei; Cao, Hua-Hua; Xu, Wen-Liang; Wang, Zi-Jin; Wang, Feng; Yang, Chuan

    2016-09-01

    To constrain the Early-Middle Paleozoic tectonic evolution of the south-eastern segment of the Central Asian Orogenic Belt (CAOB), we undertook zircon U-Pb dating and analyzed major and trace elements and zircon Hf isotope compositions of Late Cambrian to Middle Devonian igneous and metasedimentary rocks in central Jilin Province, NE China. LA-ICP-MS zircon U-Pb dating indicates that the Early-Middle Paleozoic magmatism in central Jilin Province can be divided into four episodes: Late Cambrian (ca. 493 Ma), Middle Ordovician (ca. 467 Ma), Late Ordovician-Early Silurian (ca. 443 Ma), and Late Silurian-Middle Devonian (425-396 Ma). The progression from subduction initiation to maturity is recorded by Late Cambrian low-K tholeiitic meta-diabase, Middle Ordovician medium-K calc-alkaline pyroxene andesite, and Late Ordovician to Early Silurian low-K tonalite, which all have subduction-related characteristics and formed in an evolving supra-subduction zone setting. Late Silurian to Middle Devonian calc-alkaline igneous rocks, with the lithological association of granodiorite, monzogranite, rhyolite, dacite, and trachydacite, show progressively increasing K2O contents from medium K to shoshonite series. Furthermore, the Early-Middle Devonian monzogranites are characterized by high K2O, Sr/Y, and [La/Yb]N values, indicating they were generated by the melting of thickened lower crust. These results suggest a transition from subduction to post-orogenic setting during the Late Silurian-Middle Devonian. Our interpretation is supported by the maximum age of molasse deposition in the Zhangjiatun member of the Xibiehe Formation. Overall, we suggest that Late Cambrian tholeiitic meta-diabase, Middle Ordovician pyroxene andesite, and Late Ordovician-Early Silurian tonalite formed above the northward-subducting and simultaneously seaward-retreating of Paleo-Asian Ocean plate. Subsequently, the northern arc collided with the North China Craton and post-orogenic extension occurred

  15. The last stages of the Avalonian-Cadomian arc in NW Iberian Massif: isotopic and igneous record for a long-lived peri-Gondwanan magmatic arc

    NASA Astrophysics Data System (ADS)

    Andonaegui, Pilar; Arenas, Ricardo; Albert, Richard; Sánchez Martínez, Sonia; Díez Fernández, Rubén; Gerdes, Axel

    2016-06-01

    The upper allochthonous units of NW Iberian Massif contain an extensive Cambrian magmatism (c. 500 Ma), covering felsic to mafic compositions. The magmatic activity generated large massifs of granitoids and gabbros, with calc-alkaline and tholeiitic compositions respectively. Petrological and geochemical features of these massifs are characteristic of volcanic arc. The plutons intruded siliciclastic sedimentary series deposited in the periphery of the West Africa Craton. U-Pb/Hf isotopic compositions of detrital zircon in the siliciclastic host series, indicate continental arc activity between c. 750 Ma and c. 500 Ma. It was characterized by a large variety of isotopic sources, including from very old continental input, even Archean, to the addition of a significant amount of juvenile mafic material. These isotopic sources experienced an extensive mixing that explains the composition and isotopic features (εHft from - 50 until + 15) of the represented Cambrian plutons. The Cambrian igneous rocks of the upper units of NW Iberia are related to the latest activity of the Avalonian-Cadomian arc. From the Middle Cambrian arc activity in the periphery of Gondwana was replaced by pronounced extension associated with the development of continental rifting, which finally led to separation of the microcontinent Avalonia. Subsequent drifting of Avalonia to the North caused progressive opening one of the main Paleozoic ocean, the Rheic Ocean.

  16. New Metal-Organic Chemistry of Barium, AN Aqueous Synthesis for Volatile Alkaline Earth Complexes, and Synthesis and Characterization of Thallium-Barium - Thin Films by Metal-Organic Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Schulz, Douglas Lloyd

    The synthesis and characterization of six fluorine -free barium MOCVD (metal-organic chemical vapor deposition) precursors based upon encapsulating beta -ketoiminate-polyether ligation and having the general formula Ba(RCOCHC(NR^')R ^{''})_2 (R^' = ^{rm t}butyl, R^ ' = polyether, and R^{ ''} = methyl or ^{rm t}butyl) is reported. The complexes were prepared by a nonaqueous approach which employs BaH_2 and the corresponding beta-ketoimine. These complexes have been characterized by ^1H and ^{13}C NMR spectroscopy, elemental analysis, mass spectroscopy, cryoscopic molecular weight determination, thermogravimetric analysis, and single crystal X-ray structural analysis. These complexes serve as volatile barium MOCVD precursors. Thus, BaPbO _3 films have been grown using the aforementioned barium beta-ketoiminate complexes and Pb(dipivaloylmethanate)_2 as the respective barium and lead sources, and have been characterized by X-ray diffraction, scanning electron microscopy energy dispersive X-ray spectroscopy, and variable-temperature resistivity measurements. Investigation of thermolytic decomposition of the barium beta -ketoiminate complexes led to identification of 2-methyl -4-^{rm t}butylpyridine (17), pinacolone, and 2,2-dimethyl-5-imino-3-hexanone as the major organic thermolysis products of 11, 12, and 13. The MOCVD synthesis of Tl-Ba-Ca-Cu-O thin films on novel substrates, a growth method and film configuration which is potentially applicable toward device technologies, has been investigated. These films were prepared in three steps: first, deposition of Ba-Ca-Cu-O-(F) thin films by MOCVD; next, defluorination via water/oxygen anneal; and finally, thallination using volatile thallium oxides. Films were characterized by X-ray diffraction (theta/2 theta, omega, and phi scans), variable temperature magnetization, variable temperature conductivity, and scanning and transmission electron microscopy. Attempts at preparing Tl-Ba-Ca-Cu -O thin films on Pt resulted in the

  17. Closed type alkaline storage battery

    SciTech Connect

    Hayama, H.

    1980-06-10

    The alkaline storage battery employs a metallic hat shaped terminal closure which has a piercing needle as well as a puncturable metallic diaphragm positioned below the piercing needle. The needle is fixed by caulking at its peripheral edge portion to a edge of the closure. A comparatively thick and hard metal plate is placed on the inner surface of the diaphragm and is applied to an open portion of a tubular metallic container which has a battery element. A peripheral edge portion of the closure, the diaphragm and the metallic plate are clamped in airtight relationship through a packing between the caulked end portion and an inner annular step portion of the metallic container of the battery. A lead wire extends from one polarity electrode of the battery element and is connected to a central portion of the metallic plate.

  18. Origin of lithological zoning in Alaskan-type complexes: Studies from the Duke Island and Annette Island Complexes in southeastern Alaska

    NASA Astrophysics Data System (ADS)

    Thakurta, J.; Ripley, E.; Li, C.; Stifter, E.

    2011-12-01

    Alaskan-type complexes are small, cone-shaped, ultramafic to mafic, alkaline igneous intrusive bodies which commonly occur in linear groups along the trends of major orogenic belts and subduction zones as in southeastern Alaska and the Ural Mountains in Russia. Many of these complexes are characterized by nearly concentric lithological zoning from dunite in the core followed by successive zones of wehrlite, olivine clinopyroxenite and more silicic rocks towards the rim. The Duke Island and Annette Island Complexes are two Alaskan-type complexes located in the southern tip of the Alaskan panhandle. The former is characterized by multiple lithological zones with a distorted concentric arrangement, but the latter is a single intrusion of dunite, without any noticeable development of concentric zonal structures. Both complexes have been modeled to be the products of crystal accumulation from a differentiating parental magma with the composition of picrite or ankaramite. The compositions of the residual liquids are andesitic and this is consistent with the view that the Alaskan-type complexes represent magma reservoirs for andesitic eruptions of subduction zone volcanoes. Structural and petrological relationships between the lithological units at the Duke Island Complex indicate multiple magmatic inputs from an underlying staging magma chamber in a dynamic flow through system. Evidence of magmatic differentiation is observed at the level of the intrusion and also at the level of the staging magma chamber. Conversely, the dunite unit at Annette Island is a product of rapid magmatic uplift and relatively insignificant magmatic differentiation. The spectacular development of grain-size layering and magmatic flow structures at Duke Island and on a limited scale at Annette Island clearly indicate crystallization in a dynamic magma chamber environment.

  19. Geological evolution of the Coombs Allan Hills area, Ferrar large igneous province, Antarctica: Debris avalanches, mafic pyroclastic density currents, phreatocauldrons

    NASA Astrophysics Data System (ADS)

    Ross, Pierre-Simon; White, James D. L.; McClintock, Murray

    2008-05-01

    The Jurassic Ferrar large igneous province of Antarctica comprises igneous intrusions, flood lavas, and mafic volcaniclastic deposits (now lithified). The latter rocks are particularly diverse and well-exposed in the Coombs-Allan Hills area of South Victoria Land, where they are assigned to the Mawson Formation. In this paper we use these rocks in conjunction with the pre-Ferrar sedimentary rocks (Beacon Supergroup) and the lavas themselves (Kirkpatrick Basalt) to reconstruct the geomorphological and geological evolution of the landscape. In the Early Jurassic, the surface of the region was an alluvial plain, with perhaps 1 km of mostly continental siliciclastic sediments underlying it. After the fall of silicic ash from an unknown but probably distal source, mafic magmatism of the Ferrar province began. The oldest record of this event at Allan Hills is a ≤ 180 m-thick debris-avalanche deposit (member m1 of the Mawson Formation) which contains globular domains of mafic igneous rock. These domains are inferred to represent dismembered Ferrar intrusions emplaced in the source area of the debris avalanche; shallow emplacement of Ferrar magmas caused a slope failure that mobilized the uppermost Beacon Supergroup, and the silicic ash deposits, into a pre-existing valley or basin. The period which followed ('Mawson time') was the main stage for explosive eruptions in the Ferrar province, and several cubic kilometres of both new magma and sedimentary rock were fragmented over many years. Phreatomagmatic explosions were the dominant fragmentation mechanism, with magma-water interaction taking place in both sedimentary aquifers and existing vents filled by volcaniclastic debris. At Coombs Hills, a vent complex or 'phreatocauldron' was formed by coalescence of diatreme-like structures; at Allan Hills, member m2 of the Mawson Formation consists mostly of thick, coarse-grained, poorly sorted layers inferred to represent the lithified deposits of pyroclastic density currents

  20. Distribution and origin of igneous rocks from the landward slopes of the Mariana Trench: Implications for its structure and evolution

    SciTech Connect

    Bloomer, S.H.

    1983-09-10

    The landward slope of the Mariana Trench is composed largely of igneous rocks. Serpentinites and serpentinized ultramafic rocks occur at nearly all structural levels on the slope from depths of 8000 to 1200 m. Seamountlike features on the trench slope break are the surface expression of serpentinite diapirs. Cumulate and massive gabbros are found; several varieties of volcanic rocks are common including boninites, altered and metamorphosed basalts, andesites, and dacites. The chemical characteristics of the volcanic rocks indicate that nearly all are products of island arc volcanism. Together with the gabbros, these volcanic rocks represent what is probably a late Eocene arc complex. These rocks were probably the first volcanic products to result from the subduction of the Pacific plate beneath the Phillippine Sea plate; their exposure on the trench slope today implies a significant amount of tectonic erosion of the landward slope since Eocene time. Most of this removal of material appears to have occurred during the early stages of subduction. There are isolated occurrences on the landward slope of rock assemblages including alkalic basalts, chert, hyaloclastites, upper Cretaceous siliceous sediments, and shallow water limestones. These assemblages are very similar to rocks dredged from seamounts on the offshore flank of the trench, and their presence on the landward slope suggests that since the cessation of vigorous tectonic erosion, there has been episodic accretion of seamount fragments to the landward slope.

  1. Evolution of alkaline phosphatases in primates.

    PubMed Central

    Goldstein, D J; Rogers, C; Harris, H

    1982-01-01

    Alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] in placenta, intestine, liver, kidney, bone, and lung from a variety of primate species has been characterized by quantitative inhibition, thermostability, and immunological studies. Characteristic human placental-type alkaline phosphatase occurs in placentas of great apes (chimpanzee and orangutan) but not in placentas of other primates, including gibbon. It is also present in trace amounts in human lung but not in lung or other tissues of various Old and New World monkeys. However, a distinctive alkaline phosphatase resembling it occurs in substantial amounts in lungs from Old World monkeys but not New World monkeys. It appears that duplication of alkaline phosphatase genes and mutations of genetic elements controlling their tissue expression have occurred relatively recently in mammalian evolution. Images PMID:6950431

  2. Alkaline pH sensor molecules.

    PubMed

    Murayama, Takashi; Maruyama, Ichiro N

    2015-11-01

    Animals can survive only within a narrow pH range. This requires continual monitoring of environmental and body-fluid pH. Although a variety of acidic pH sensor molecules have been reported, alkaline pH sensor function is not well understood. This Review describes neuronal alkaline pH sensors, grouped according to whether they monitor extracellular or intracellular alkaline pH. Extracellular sensors include the receptor-type guanylyl cyclase, the insulin receptor-related receptor, ligand-gated Cl- channels, connexin hemichannels, two-pore-domain K+ channels, and transient receptor potential (TRP) channels. Intracellular sensors include TRP channels and gap junction channels. Identification of molecular mechanisms underlying alkaline pH sensing is crucial for understanding how animals respond to environmental alkaline pH and how body-fluid pH is maintained within a narrow range.

  3. The Igneous Architecture of IODP Hole U1309D: Constructing Oceanic Crust from Multiple Sills

    NASA Astrophysics Data System (ADS)

    Christofferson, C. A.; John, B. E.; Cheadle, M. J.; Swapp, S. M.; Grimes, C. B.

    2010-12-01

    Gabbroic rocks comprise a significant portion of the footwall of many oceanic core complexes. The decreasing age of these gabbros from the breakaway to the termination suggests that they are continuously accreted as the bounding detachment fault slips. But, questions remain; how are these large (>1 km diameter) gabbroic bodies constructed and at what scale and frequency is melt added to the system? Here we report a detailed lithologic analysis of IODP Hole U1309D drilled into the Atlantis Massif core complex (30° N, MAR). We present new, high resolution (1m scale) downhole lithological diagrams, compiled from observations of the archive core, refined using other available data including magnetic susceptibility. These data show that the thickness of the individual magmatic units is on the order of 1 to a few 10’s of m. Contacts between many of these units are sharp; many of the units are interpreted to result from small injections of melt as opposed to in-situ fractionation. However, these units are often disaggregated by later intrusive bodies and hence, it is likely that individual gabbro units were initially somewhat thicker. Downhole plots of magmatic fabric dip from both shipboard data and new electron backscatter diffraction (EBSD) data are consistent with the units having initially been intruded as sills, and subsequently rotated by ~40-50°, as constrained by paleomagnetic data (Morris et al., 2009). Using all of the available data, we propose the IODP Hole 1309D gabbro section is a composite body that grew episodically by relatively small (10’s m) repeated sill-like injections of melt. We conclude that the melt lens that formed these gabbros was relatively small at any one time. The EBSD data also provide textural constraints on the model for crustal accretion. Gabbroic samples analyzed so far show a moderate to weak plagioclase and clinopyroxene foliation, similar to those in continental mafic intrusions and are thus interpreted to be magmatic fabrics

  4. Proteomic analysis of protein expression in Lactobacillus plantarum in response to alkaline stress.

    PubMed

    Lee, KiBeom; Rho, Beom-Seop; Pi, KyungBae; Kim, Ho-Jin; Choi, Yun-Jaie

    2011-04-20

    Lactobacillus plantarum, a probiotic organism that plays an important role in the microbial fermentation of alkaline materials in fermenting foods, faces alkaline stress during the fermentation process. Here, we report the patterns of protein expression in L. plantarum subjected to transient (1h) alkaline stress at pH 7.7, 8.7 or 9.7. Thirty-three alkaline-responsive proteins were identified by two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS). Identification of proteins showing differential expression in response to alkaline stress revealed that the alkaline stress response of L. plantarum is a complex process. Some proteins appear to be induced, others repressed. These proteins could be clustered into nine groups based on their probable functions: energy metabolism, transport system, purine/pyrimidine metabolism, amino acid metabolism, proteolytic activity, transcription-translation, stress-related, general function, and unknown functions. These proteomic analyses are expected to prove useful in understanding the adaptive response of L. plantarum strains to alkaline stress and may facilitate future investigations into the genetic and physiological aspects of this response.

  5. Re-examining the doming uplift model of Emeishan Large Igneous Province (SW China): evidence from high-resolution conodont biostratigraphy and sedimentology

    NASA Astrophysics Data System (ADS)

    Yadong, S.; Wignall, P. B.; Ali, J. R.; Widdowson, M.; Bond, D. P.; Lai, X.

    2010-12-01

    stages of volcanism, which is itself further evidence against kilometre-scale up-doming (Wignall et al., 2009, Ali et al., 2010, Sun et al., 2010). We argue that the mantle plume which generated the Emeishan large igneous province 260-odd million years ago, resulted in a complex interaction between plume and overlying lithosphere, and was characterized by localized minor uplift and subsidence. References: Ali et al., 2010. Emeishan Large igneous Province (SW China) and the mantle plume up-doming hypothesis. J. Geol. Soc. Lond. 167, 953-959. Sun et al., 2010. Dating the onset and nature of the Middle Permian Emeishan large igneous province eruptions in SW China using conodont biostratigraphy and its bearing on mantle plume uplift models. Lithos doi: 10.1016/j.lithos.2010.05.012. Wignall et al., 2009. Volcanism, Mass Extinction, and Carbon Isotope Fluctuations in the Middle Permian of China. Science 324, 1179-1182.

  6. Subcellular localization of alkaline phosphatase in Bacillus licheniformis 749/C by immunoelectron microscopy with colloidal gold

    SciTech Connect

    Tinglu, G.; Ghosh, A.; Ghosh, B.K.

    1984-08-01

    Subcellular distribution of the alkaline phosphatase of Bacillus licheniformis 749/C was determined by an immunoelectron microscopy method. Anti-alkaline phosphatase antibody labeled with 15- to 18-nm colloidal gold particles (gold-immunoglobulin G (IgG) complex) were used for the study. Both the plasma membrane and cytoplasmic material were labeled with the gold-IgG particles. These particles formed clusters in association with the plasma membrane; in contrast, in the cytoplasm the particles were largely dispersed, and only a few clusters were found. The gold-IgG binding was quantitatively estimated by stereological analysis of labeled, frozen thin sections. This estimation of a variety of control samples showed that the labeling was specific for the alkaline phosphatase. Cluster formation of the gold -IgG particles in association with the plasma membrane suggests that existence of specific alkaline phosphatase binding sites (receptors) in the plasma membrane of B. licheniformis 749/C. 27 references, 6 figures, 1 table.

  7. On the scale-invariance of fractures and fracture patterns in the Transscandinavian Igneous Belt, Southeast Sweden

    NASA Astrophysics Data System (ADS)

    Krumbholz, M.; Burchardt, S.; Tanner, D. C.; Koyi, H.

    2012-04-01

    Fracture dimensions and their spatial distribution are of primary importance in many fields of applied geology, e.g. they determine the quality of sites for the long-term storage of hazardous waste and fractured reservoirs for e.g. hydrocarbons, CO2 sequestration, and geothermal energy. Unfortunately, the observation of fracture systems is commonly limited by the outcrop size or the resolution of the measuring method. Fractures and fracture properties are often assumed to be scale-invariant, albeit within a certain range. Therefore, knowing the fractal dimension of fracture properties allows conclusions to be drawn from one particular scale to another. We investigated fracture trace lengths and patterns at map-, outcrop- and handspecimen scale, covering a large area in the Transscandinavian Igneous Belt. The dataset comprises 11 fracture maps at three different scales containing 8641 fracture trace lengths. Analysis of the fracture trace lengths was carried out using cumulative frequency distributions, while the fracture patterns were analysed with the standard box-counting technique. Combining the three analysed scales, our results indicate that the fracture trace lengths can be considered to be scale-invariant with a fractal dimension of about 1.8. In contrast, the fractal dimension at one particular scale could not be determined, probably due to censoring and truncation effects. Analyses with the box-counting method show that the fracture patterns, in contrast to fracture trace lengths, are not scale-invariant. The box-counting dimension increases with increasing scale. It is a measure of the complexity and maturity of a fracture system, which increases with scale. Consequently, the complexity of fracture pattern is scale-variant.

  8. Process for extracting technetium from alkaline solutions

    DOEpatents

    Moyer, Bruce A.; Sachleben, Richard A.; Bonnesen, Peter V.

    1995-01-01

    A process for extracting technetium values from an aqueous alkaline solution containing at least one alkali metal hydroxide and at least one alkali metal nitrate, the at least one alkali metal nitrate having a concentration of from about 0.1 to 6 molar. The solution is contacted with a solvent consisting of a crown ether in a diluent for a period of time sufficient to selectively extract the technetium values from the aqueous alkaline solution. The solvent containing the technetium values is separated from the aqueous alkaline solution and the technetium values are stripped from the solvent.

  9. Alkaline sorbent injection for mercury control

    DOEpatents

    Madden, Deborah A.; Holmes, Michael J.

    2002-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  10. Alkaline sorbent injection for mercury control

    DOEpatents

    Madden, Deborah A.; Holmes, Michael J.

    2003-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  11. Igneous rocks of Arctic Ocean deep sea ridges: new data on petrology, geochemistry and geochronology

    NASA Astrophysics Data System (ADS)

    Petrov, Oleg; Morozov, Andrey; Shokalsky, Sergey; Sobolev, Nikolay; Kashubin, Sergey; Shevchenko, Sergey; Sergeev, Sergey; Belyatsky, Boris; Shatov, Vitaly; Petrov, Eugeny

    2015-04-01

    The aggregate results of studies of igneous rocks, collected from the central part of the Arctic Ocean during scientific marine expeditions «Arctic-2000, 2005, 2007 and 2012» are presented and discussed in the frame of modern understanding of High Polar Arctic tectonic constraint. Petrological, geochemical and isotope-geochronological studies of more than 500 samples have shown that the sedimentary rocks are of dominated population among the rock fragments dredged from deep-sea bottom, and represented by metamorphosed dolomite and quartz sandstone, limestone, sometimes with the Devonian - Permian fauna. Igneous rocks are 10-15% only (Archean and Paleoproterozoic gneissouse granites and gabbro, Neoproterozoic dolerite) and metamorphic rocks (green shales, metabasites, gneisses). Apparently, these rocks are part of the acoustic basement underlying the Late Mesozoic - Cenozoic layered loose sediments. In addition to the dredged fragments of the ancient mafic rocks, some samples were taken as a core during deep-water drilling in the northern and southern slopes of the Mendeleev Ridge and represented by trachybasalts, marking the border of Late-Cenozoic deposit cover and acoustic basement and quite similar in composition to those of Early-Late Cretaceous basalts form northward of the Chukchi Plateau seamounts, Alpha Ridge, Franz Josef Land, De Long islands and other parts of the large igneous province of the High Arctic (HALIP). Video-filming of Mendeleev Ridge escarps proofs the existing of rock outcrops and supports local origin of most of the rock fragments found in the sampling areas. Thus the continental type of the earth's crust of the Central Arctic Ridges basement is based on all obtained results of our study of sea-bottom excavated rock material.

  12. Classification of mafic clasts from mesosiderites: Implications for endogenous igneous processes

    SciTech Connect

    Rubin, A.E. ); Mittlefehldt, D.W. )

    1992-02-01

    The authors have analyzed thirteen igneous pebbles from the Vaca Muerta, EET87500, and Bondoc mesosiderites by electron microprobe and instrumental neutron activation and combined these data with literature data for forty-three analyzed mesosiderite clasts. They classify these well-characterized clasts into the following five principal groups: (1) Polygenic and monogenic cumulates (39%) are coarse-grained gabbros that are highly depleted in incompatible elements (relative to H chondrites); they formed at moderate depth either as residues of low-degree partial melting of pre-existing cumulate eucrites or as cumulates from parent melts similar to cumulate eucrites. (2) Polygenic basalts (30%) are finer-grained rocks with positive europium anomalies, La/Lu ratios < 1, and lower rare earth element abundances than basaltic eucrites. It seems likely that these rocks were formed near their parent body surface by remelting mixtures of major amounts of basaltic eucrites and lesser amounts of cumulate eucrites. (3) Quench-textured rocks comprise two compositional groups, (a) those which resemble basaltic eucrites (5%), and (b) those which resemble cumulate eucrites (2%). The quench-textured rocks are probably monogenic; they formed most likely when small-scale impacts at their parent body surface totally melted small amounts of basaltic or cumulate eucrite material. (4) Monogenic basalts (11%) resemble basaltic eucrites and formed by endogenous igneous processes on the mesosiderite parent body (MPB). (5) Ultramafic rocks are cumulates consisting mainly of large crystals of orthopyroxene (9%) or olivine (4%). Orthopyroxenite clasts closely resemble diogenites and were formed most likely by endogenous igneous processes.

  13. Log-ratio transformed major element based multidimensional classification for altered High-Mg igneous rocks

    NASA Astrophysics Data System (ADS)

    Verma, Surendra P.; Rivera-Gómez, M. Abdelaly; Díaz-González, Lorena; Quiroz-Ruiz, Alfredo

    2016-12-01

    A new multidimensional classification scheme consistent with the chemical classification of the International Union of Geological Sciences (IUGS) is proposed for the nomenclature of High-Mg altered rocks. Our procedure is based on an extensive database of major element (SiO2, TiO2, Al2O3, Fe2O3t, MnO, MgO, CaO, Na2O, K2O, and P2O5) compositions of a total of 33,868 (920 High-Mg and 32,948 "Common") relatively fresh igneous rock samples. The database consisting of these multinormally distributed samples in terms of their isometric log-ratios was used to propose a set of 11 discriminant functions and 6 diagrams to facilitate High-Mg rock classification. The multinormality required by linear discriminant and canonical analysis was ascertained by a new computer program DOMuDaF. One multidimensional function can distinguish the High-Mg and Common igneous rocks with high percent success values of about 86.4% and 98.9%, respectively. Similarly, from 10 discriminant functions the High-Mg rocks can also be classified as one of the four rock types (komatiite, meimechite, picrite, and boninite), with high success values of about 88%-100%. Satisfactory functioning of this new classification scheme was confirmed by seven independent tests. Five further case studies involving application to highly altered rocks illustrate the usefulness of our proposal. A computer program HMgClaMSys was written to efficiently apply the proposed classification scheme, which will be available for online processing of igneous rock compositional data. Monte Carlo simulation modeling and mass-balance computations confirmed the robustness of our classification with respect to analytical errors and postemplacement compositional changes.

  14. Geochemistry of the Kalkarindji Magmas: Insights into the Source of the Oldest Phanerozoic Large Igneous Province

    NASA Astrophysics Data System (ADS)

    Ware, B. D.; Jourdan, F.; Hodges, K.; Tessalina, S.; Chiaradia, M.; Evins, L.; Gole, M.

    2014-12-01

    The Kalkarindji continental flood basalt province (CFBP) of northern Australia is the oldest Phanerozoic large igneous province (LIP) in the world. The extent of this Middle Cambrian LIP has been estimated to at least 2.1 x 106 km2 with exposures in Western Australia, Northern Territory, Queensland, and South Australia. The research into Kalkarindji is still in its infancy with only a handful of studies published. The rocks of the Kalkarindji province occur as lava flows, sills, dykes, and volcanic tuffs. Kalkarindji has been linked to an extinction event at the Early-Middle Cambrian boundary. The Kalkarindji province displays Low-Ti values and high SiO2 values compared to other large igneous provinces, enriched 87Sr/86Sr values, and low 187Os/188Os. This project presents a large data set of new geochemical analyses of the various constituents of the Kalkarindji CFBP. Source mixing calculations, assimilation and fractionation models, coupled with Monte Carlo simulations were carried out to understand the petrogenesis of the province. The trace element and 87Sr/86Sr values indicate a contribution of enriched crustal-like material into the source region; however, the Os values fall into typical mantle ranges. These geochemical patterns suggest that the mantle source(s) of the Kalkarindji CFBP has been directly enriched at some stage of history, before the emplacement of the province. This study will provide further insights into the magma source and origin processes needed to create one of the world's largest and oldest Phanerozoic large igneous provinces.

  15. Diverse sources for igneous blocks in Franciscan melanges, California Coast Ranges

    SciTech Connect

    MacPherson, G.J. ); Phipps, S.P. ); Grossman, J.N. )

    1990-11-01

    Igneous blocks in Franciscan melanges are of three chemical-petrologic types: (1) tholeiitic basalts of both arc and spreading center origin, with depletions in light relative to heavy rare-earth elements, 3% > TiO{sub 2} > 1%, high Y/Zr and Y/Ti ratios, and relict augites that generally have low Al and Ti and well-defined iron-enrichment trends; (2) basalts of probable seamount origin with marked enrichments in light relative to heavy rare-earth elements, 5% > TiO{sub 2} > 1%, lower Y/Zr and Y/Ti than (1), and Ti-Al-rich augites showing little if any iron-enrichment trends; and (3) hypabyssal intrusives having SiO{sub 2} > 52%, TiO{sub 2} < 1%, flat or only slightly fractionated rare-earth-abundance patterns, and diopsidic augites that are very low in Ti and Al and show no iron-enrichment trends. All of the blocks are metamorphosed; most are undeformed pumpellyite-bearing greenstones, and a few contain sodic amphibole {plus minus} lawsonite {plus minus} sodic pyroxene. The melanges are probably olistostromal in origin, deriving their igneous block detritus both from the downgoing Pacific plate (ocean floor basalts and seamounts) and from the hanging wall of the Franciscan trench (basalts and arc-related silic intrusive rocks). The silicic intrusive rocks and some of the basalts are eroded fragments of the fore-arc crust that ultimately become the Coast Range Ophiolite. These fragments were incorporated into the Franciscan trench fill and subducted. Results suggest that the igneous blocks in ophiolitic melanges provide important information about melange formation and about the tectonics and paleogeography of the regions in which the melanges are found.

  16. Lead isotope systematics of some igneous rocks from the Egyptian Shield

    NASA Technical Reports Server (NTRS)

    Gillespie, J. G.; Dixon, T. H.

    1983-01-01

    Lead isotope data on whole-rock samples and two feldspar separates for a variety of Pan-African (late Precambrian) igneous rocks for the Egyptian Shield are presented. It is pointed out that the eastern desert of Egypt is a Late Precambrian shield characterized by the widespread occurrence of granitic plutons. The lead isotope ratios may be used to delineate boundaries between Late Precambrian oceanic and continental environments in northeastern Africa. The samples belong to three groups. These groups are related to a younger plutonic sequence of granites and adamellites, a plutonic group consisting of older tonalites to granodiorites, and the Dokhan volcanic suite.

  17. Diverse, Alkali-Rich Igneous and Volcaniclastic Rocks Reflect a Metasomatised Mantle Beneath Gale Crater

    NASA Astrophysics Data System (ADS)

    Schmidt, M. E.; Baker, M. B.; Berger, J. A.; Fisk, M. R.; Gellert, R.; McLennan, S. M.; Newcombe, M. E.; Stolper, E. M.; Thompson, L. M.

    2014-12-01

    Although Curiosity landed in a sedimentary setting, geochemical compositions determined by Alpha Particle X-ray Spectrometer (APXS) and ChemCam suggest that major element concentrations of some rocks were little modified by chemical weathering, and in these cases, the bulk (>70%) of the crystalline components determined by ChemMin are igneous. Gale rocks can therefore largely preserve the composition of their igneous protoliths and provide insight into the crystalline basement exposed in the north crater rim. Four end-member compositions are recognized on the basis of APXS analyses. (1) The diverse, evolved Jake M class (n=12) of inferred igneous origin includes float blocks and cobbles. Jake M rocks are phonotephritic/mugearitic to trachyandesitic and characterized by low MgO contents (3.0-5.7 wt%) and high Al and alkalis, particularly Na2O (up to 7.35 wt%). (2) The Bathurst class of siltstones to coarse sandstones (n=13) occurs as dark-toned float and bedded outcrop and is basaltic to trachybasaltic, ranging to high K2O (up to 3.8 wt%). Alteration of the protolith(s) or during diagenesis may have affected this class. (3) The Darwin class of conglomerates to coarse sandstones (n=10) has high Na and Al, likely reflecting a sodic plagioclase-rich mineralogy, but with higher Fe than Jake M class (13.0-17.1 vs. 6.0-12.5 wt%). (4) The low alkali "normal" Mars basaltic composition is typified by the Portage soils (n=6) and the John Klein class (n=13; includes the Sheepbed mudstone). Some degree of mixing and/or contamination with this low alkali basaltic compositon has affected all APXS analyses. Overall, Gale rocks are strongly enriched in total alkalis (at the same MgO) relative to basaltic shergottites and many have higher K2O than igneous rocks analyzed by Spirit and Opportunity, suggesting that the mantle beneath Gale is alkali-rich (likely as a result of a metasomatic event) and that alkalis are heterogeneously distributed in the planet's interior.

  18. Trace element partitioning in rock forming minerals of co-genetic, subduction-related alkaline and tholeiitic mafic rocks in the Ural Mountains, Russia

    NASA Astrophysics Data System (ADS)

    Krause, J.; Brügmann, G. E.; Pushkarev, E. V.

    2009-04-01

    The partitioning of trace elements between rock forming minerals in igneous rocks is largely controlled by physical and chemical parameters e.g. temperature, pressure and chemical composition of the minerals and the coexisting melt. In the present study partition coefficients for REE between hornblende, orthopyroxene, feldspars, apatite and clinopyroxene in a suite of co-genetic alkaline and tholeiitic mafic rocks from the Ural Mountains (Russia) were calculated. The results give insights to the influence of the chemical composition of the parental melt on the partitioning behaviour of the REE. Nepheline-bearing, alkaline melanogabbros (tilaites) are assumed to represent the most fractionated products of the melt that formed the ultramafic cumulates in zoned mafic-ultramafic complexes in the Ural Mountains. Co-genetic with the latter is a suite of olivine gabbros, gabbronorites and hornblende gabbros formed from a tholeiitic parental melt. Negative anomalies for the HFSE along with low Nb and Ta contents and a positive Sr anomaly indicate a subduction related origin of all parental melts. The nepheline gabbros consist predominantly of coarse-grained clinopyroxene phenocrysts in a matrix of fine grained clinopyroxene, olivine, plagioclase, K-feldspar and nepheline with accessory apatite. The tholeiitic gabbros have equigranular to porphyric textures with phenocrysts of olivine, pyroxene and hornblende in a plagioclase rich matrix with olivine hornblende, pyroxene and accessory apatite. Element concentrations of adjacent matrix grains and rims of phenochrysts were measured with LA-ICPMS. The distribution of REE between hornblende and clinopyroxene in the tholeiitic rocks is similar for most of the elements (DHbl•Cpx(La-Tm) = 2.7-2.8, decreasing to 2.6 and 2.4 for Yb and Lu, respectively). These values are about two times higher than published data (e.g. Ionov et al. 1997). Partition coefficients for orthopyroxene/clinopyroxene systematically decrease from the HREE

  19. K-Ar ages of allochthonous mafic and ultramafic complexes and their metamorphic aureoles, Western Brooks Range, Alaska

    SciTech Connect

    Boak, J.L.; Turner, D.L.; Wallace, W.K.; Moore, T.E.

    1985-04-01

    New K-Ar ages from allochthonous mafic and ultramafic complexes of the western Brooks Range (Brooks Range ophiolite) show that igneous rocks yielded ages nearly identical to those of underlying metamorphic aureole rocks. Dated rocks of the Misheguk igneous sequence from Tumit Creek consist of (1) hornblende gabbro with minor greenschist and lower grade alteration, hornblende age 147.2 +/- 4.4 Ma; and (2) hornblende-bearing diorite, also slightly altered, age 155.8 +/- 4.7 Ma. Both samples come from presumed higher levels of the Misheguk sequence. Dated samples of metamorphic aureole rocks come from outcrops near Kismilot Creek and lie structurally beneath the Iyikrok Mountain peridotite body. The rocks consist of amphibolite and garnet-bearing biotite-hornblende gneiss considered to be metamorphosed Copter igneous sequence and related sedimentary rocks. Hornblende ages are 154.2 +/- 4.6 Ma and 153.2 +/- 4.6 Ma. metamorphism is clearly related to the structurally overlying perioditite, as the degree of alteration decreases downward. The authors suggest that the K-Ar ages of these rocks represent the effects of thermal metamorphism post-dating igneous crystallization, and are related to tectonic emplacement of the complex. Earlier K-Ar data on igneous rocks give similar ages and have been interpreted as reflecting tectonothermal events. The age of igneous crystallization of the mafic and ultramafic rocks of the Misheguk igneous sequence remains uncertain.

  20. Possible petrogenetic associations among igneous components in North Massif soils: Evidence in 2-4 MM soil particles from 76503

    NASA Astrophysics Data System (ADS)

    Jolliff, Bradley L.; Bishop, Kaylynn M.; Haskin, Larry A.

    1992-12-01

    Studies of Apollo 17 highland igneous rocks and clasts in breccias from the North and South Massifs have described magnesian troctolite, norite, anorthositic gabbro, dunite, spinel cataclasites, and granulitic lithologies that may have noritic anothosite or anorthositic norite/gabbro as igneous precursors, and have speculated on possible petrogenetic relationships among these rock types. Mineral compositions and relative proportions of plagioclase and plagioclase-olivine particles in samples 76503 indicate that the precursor lithology of those particles were troctolitic anorthosite, not troctolite. Mineral and chemical compositions of more pyroxene-rich, magnesian breccias and granulites in 76503 indicate that their precursor lithology was anorthositic norite/gabbro. The combination of mineral compositions and whole-rock trace-element compositional trends supports a genetic relationship among these two groups as would result from differentiation of a single pluton. Although highland igneous lithologies in Apollo 17 materials have been described previously, the proportions of different igneous lithologies present in the massifs, their frequency of association, and how they are related are not well known. We consider the proportions of, and associations among, the igneous lithologies found in a North Massif soil, which may represent those of the North Massif or a major part of it.

  1. Possible petrogenetic associations among igneous components in North Massif soils: Evidence in 2-4 mm soil particles from 76503

    NASA Technical Reports Server (NTRS)

    Jolliff, Bradley L.; Bishop, Kaylynn M.; Haskin, Larry A.

    1992-01-01

    Studies of Apollo 17 highland igneous rocks and clasts in breccias from the North and South Massifs have described magnesian troctolite, norite, anorthositic gabbro, dunite, spinel cataclasites, and granulitic lithologies that may have noritic anothosite or anorthositic norite/gabbro as igneous precursors, and have speculated on possible petrogenetic relationships among these rock types. Mineral compositions and relative proportions of plagioclase and plagioclase-olivine particles in samples 76503 indicate that the precursor lithology of those particles were troctolitic anorthosite, not troctolite. Mineral and chemical compositions of more pyroxene-rich, magnesian breccias and granulites in 76503 indicate that their precursor lithology was anorthositic norite/gabbro. The combination of mineral compositions and whole-rock trace-element compositional trends supports a genetic relationship among these two groups as would result from differentiation of a single pluton. Although highland igneous lithologies in Apollo 17 materials have been described previously, the proportions of different igneous lithologies present in the massifs, their frequency of association, and how they are related are not well known. We consider the proportions of, and associations among, the igneous lithologies found in a North Massif soil, which may represent those of the North Massif or a major part of it.

  2. Cadomian magmatism and metamorphism at the Ossa Morena/Central Iberian zone boundary, Iberian Massif, Central Portugal: Geochemistry and P-T constraints of the Sardoal Complex

    NASA Astrophysics Data System (ADS)

    Henriques, S. B. A.; Neiva, A. M. R.; Tajčmanová, L.; Dunning, G. R.

    2017-01-01

    A well preserved Cadomian basement is exposed in the Iberian Massif, Central Portugal, at the Ossa Morena/Central Iberian zone boundary, which allows the determination of reliable geochemical data. A sequence of Cadomian and Variscan magmatic and tectonometamorphic events has been already described for this area and are documented in other areas of the Avalonian-Cadomian orogen. However, the geochemical information concerning the Cadomian basement for this area is still limited. We present whole rock geochemical and oxygen isotopic information to characterize the igneous protoliths of the Sardoal Complex, located within the Tomar-Badajoz-Córdoba Shear Zone, and identify their tectonic setting. We use detailed petrography, mineral chemistry and P-T data to characterize the final Cadomian tectonometamorphic event. The Sardoal Complex contains orthogneiss and amphibolite units. The protoliths of the orthogneiss are calc-alkaline magmas of acid composition and peraluminous character that were generated in an active continental margin in three different stages (ca. 692 Ma, ca. 569 Ma and ca. 548 Ma). The most significant processes in their petrogenesis are the partial melting of old metasedimentary and meta-igneous crust at different crustal levels and the crystal fractionation of plagioclase, alkali feldspars, apatite, zircon and Fe-Ti oxides. The protoliths of the amphibolite, older than ca. 540 Ma, are tholeiitic and calc-alkaline magmas of basic composition that display N-, T- and E-MORB affinities. They were generated in an active continental margin. Crustal contamination and fractional crystallization of hornblende and diopside were involved in their petrogenesis. However, the fractional crystallization was not significant. The magmatic activity recorded in the Sardoal Complex indicates the existence of a long-lived continental arc (ca. 692-540 Ma) with coeval felsic and mafic magmatism. The final stage of the Cadomian metamorphism is usually represented in other

  3. Tracing the Cambro-Ordovician ferrosilicic to calc-alkaline magmatic association in Iberia by in situ U-Pb SHRIMP zircon geochronology (Gredos massif, Spanish Central System batholith)

    NASA Astrophysics Data System (ADS)

    Díaz-Alvarado, Juan; Fernández, Carlos; Chichorro, Martim; Castro, Antonio; Pereira, Manuel Francisco

    2016-06-01

    U-Pb geochronological study of zircons from nodular granites and Qtz-diorites comprising part of Variscan high-grade metamorphic complexes in Gredos massif (Spanish Central System batholith) points out the significant presence of Cambro-Ordovician protoliths among the Variscan migmatitic rocks that host the Late Carboniferous intrusive granitoids. Indeed, the studied zone was affected by two contrasted tectono-magmatic episodes, Carboniferous (Variscan) and Cambro-Ordovician. Three main characteristics denote a close relation between the Cambro-Ordovician protholiths of the Prado de las Pozas high-grade metamorphic complex, strongly reworked during the Variscan Orogeny, and other Cambro-Ordovician igneous domains in the Central Iberian Zone of the Iberian Massif: (1) geochemical features show the ferrosilicic signature of nodular granites. They plot very close to the average analysis of the metavolcanic rocks of the Ollo de Sapo formation (Iberia). Qtz-diorites present typical calc-alkaline signatures and are geochemically similar to intermediate cordilleran granitoids. (2) Both Qtz-diorite and nodular granite samples yield a significant population of Cambro-Ordovician ages, ranging between 483 and 473 Ma and between 487 and 457 Ma, respectively. Besides, (3) the abundance of zircon inheritance observed on nodular granites matches the significant component of inheritance reported on Cambro-Ordovician metagranites and metavolcanic rocks of central and NW Iberia. The spatial and temporal coincidence of both peraluminous and intermediate granitoids, and specifically in nodular granites and Qtz-diorite enclaves of the Prado de las Pozas high-grade complex, is conducive to a common petrogenetic context for the formation of both magmatic types. Tectonic and geochemical characteristics describe the activity of a Cambro-Ordovician arc-back-arc tectonic setting associated with the subduction of the Iapetus-Tornquist Ocean and the birth of the Rheic Ocean. The extensional

  4. Alkaline phytase from lily pollen: Investigation of biochemical properties.

    PubMed

    Jog, Sonali P; Garchow, Barry G; Mehta, Bakul Dhagat; Murthy, Pushpalatha P N

    2005-08-15

    Phytases catalyze the hydrolysis of phytic acid (InsP6, myo-inositol hexakisphosphate), the most abundant inositol phosphate in cells. In cereal grains and legumes, it constitutes 3-5% of the dry weight of seeds. The inability of humans and monogastric animals such as swine and poultry to absorb complexed InsP6 has led to nutritional and environmental problems. The efficacy of supplemental phytases to address these issues is well established; thus, there is a need for phytases with a range of biochemical and biophysical properties for numerous applications. An alkaline phytase that shows unique catalytic properties was isolated from plant tissues. In this paper, we report on the biochemical properties of an alkaline phytase from pollen grains of Lilium longiflorum. The enzyme exhibits narrow substrate specificity, it hydrolyzed InsP6 and para-nitrophenyl phosphate (pNPP). Alkaline phytase followed Michaelis-Menten kinetics with a K(m) of 81 microM and V(max) of 217 nmol Pi/min/mg with InsP6 and a K(m) of 372 microM and V(max) of 1272 nmol Pi/min/mg with pNPP. The pH optimum was 8.0 with InsP6 as the substrate and 7.0 with pNPP. Alkaline phytase was activated by calcium and inactivated by ethylenediaminetetraacetic acid; however, the enzyme retained a low level of activity even in Ca2+-free medium. Fluoride as well as myo-inositol hexasulfate did not have any inhibitory affect, whereas vanadate inhibited the enzyme. The enzyme was activated by sodium chloride and potassium chloride and inactivated by magnesium chloride; the activation by salts followed the Hofmeister series. The temperature optimum for hydrolysis is 55 degrees C; the enzyme was stable at 55 degrees C for about 30 min. The enzyme has unique properties that suggest the potential to be useful as a feed supplement.

  5. Alkaline tolerant dextranase from streptomyces anulatus

    DOEpatents

    Decker, Stephen R.; Adney, William S.; Vinzant, Todd B.; Himmel, Michael E.

    2003-01-01

    A process for production of an alkaline tolerant dextranase enzyme comprises culturing a dextran-producing microorganism Streptomyces anulatus having accession no. ATCC PTA-3866 to produce an alkaline tolerant dextranase, Dex 1 wherein the protein in said enzyme is characterized by a MW of 63.3 kDa and Dex 2 wherein its protein is characterized by a MW of 81.8 kDa.

  6. Technetium recovery from high alkaline solution

    DOEpatents

    Nash, Charles A.

    2016-07-12

    Disclosed are methods for recovering technetium from a highly alkaline solution. The highly alkaline solution can be a liquid waste solution from a nuclear waste processing system. Methods can include combining the solution with a reductant capable of reducing technetium at the high pH of the solution and adding to or forming in the solution an adsorbent capable of adsorbing the precipitated technetium at the high pH of the solution.

  7. Toxicity of alkalinity to Hyalella azteca

    USGS Publications Warehouse

    Lasier, P.J.; Winger, P.V.; Reinert, R.E.

    1997-01-01

    Toxicity testing and chemical analyses of sediment pore water have been suggested for use in sediment quality assessments and sediment toxicity identification evaluations. However, caution should be exercised in interpreting pore-water chemistry and toxicity due to inherent chemical characteristics and confounding relationships. High concentrations of alkalinity, which are typical of sediment pore waters from many regions, have been shown to be toxic to test animals. A series of tests were conducted to assess the significance of elevated alkalinity concentrations to Hyalella azteca, an amphipod commonly used for sediment and pore-water toxicity testing. Toxicity tests with 14-d old and 7-d old animals were conducted in serial dilutions of sodium bicarbonate (NaHCO3) solutions producing alkalinities ranging between 250 to 2000 mg/L as CaCO3. A sodium chloride (NaCl) toxicity test was also conducted to verify that toxicity was due to bicarbonate and not sodium. Alkalinity was toxic at concentrations frequently encountered in sediment pore water. There was also a significant difference in the toxicity of alkalinity between 14-d old and 7-d old animals. The average 96-h LC50 for alkalinity was 1212 mg/L (as CaCO3) for 14-d old animals and 662 mg/L for the younger animals. Sodium was not toxic at levels present in the NaHCO3 toxicity tests. Alkalinity should be routinely measured in pore-water toxicity tests, and interpretation of toxicity should consider alkalinity concentration and test-organism tolerance.

  8. Alkaline Water and Longevity: A Murine Study

    PubMed Central

    Magro, Massimiliano; Corain, Livio; Ferro, Silvia; Baratella, Davide; Bonaiuto, Emanuela; Terzo, Milo; Corraducci, Vittorino; Salmaso, Luigi; Vianello, Fabio

    2016-01-01

    The biological effect of alkaline water consumption is object of controversy. The present paper presents a 3-year survival study on a population of 150 mice, and the data were analyzed with accelerated failure time (AFT) model. Starting from the second year of life, nonparametric survival plots suggest that mice watered with alkaline water showed a better survival than control mice. Interestingly, statistical analysis revealed that alkaline water provides higher longevity in terms of “deceleration aging factor” as it increases the survival functions when compared with control group; namely, animals belonging to the population treated with alkaline water resulted in a longer lifespan. Histological examination of mice kidneys, intestine, heart, liver, and brain revealed that no significant differences emerged among the three groups indicating that no specific pathology resulted correlated with the consumption of alkaline water. These results provide an informative and quantitative summary of survival data as a function of watering with alkaline water of long-lived mouse models. PMID:27340414

  9. Performed surfactant-optimized aqueous alkaline flood

    SciTech Connect

    Thigpen, D.R.; Lawson, J.B.; Nelson, R.C.

    1991-11-26

    This paper describes improvement in a process for recovering oil from an acidic oil reservoir by injecting an aqueous alkaline solution comprising water, sodium chloride, and alkaline material for reacting with the reservoir oil forming a petroleum acid soap to form an in-situ surfactant system. The improvement comprises: selecting a preformed cosurfactant which is soluble in both the aqueous solution and the reservoir oil and has a solubility ratio which is grater than the solubility ratio of the petroleum acid soap where the solubility ratio is the ratio of solubility in the aqueous alkaline solution to the solubility in the reservoir oil; combining with the alkaline solution an amount of the preformed cosurfactant which will result in the in-situ surfacant system having a salinity about equal to a salinity which results in minimal interfacial tension between the oil in the reservoir and the in-situ surfactant system at reservoir temperature, wherein the amount of the preformed cosurfactant is about 0.3 percent by weight in the aqueous alkaline solution; and injecting the cosurfactant-aqueous alkaline solution mixture into the reservoir to displace oil toward a fluid production location.

  10. Zirconolite: A new U-Pb chronometer for mafic igneous rocks

    NASA Astrophysics Data System (ADS)

    Rasmussen, Birger; Fletcher, Ian R.

    2004-09-01

    Precise dates for mafic igneous events are essential for tectonic reconstructions and understanding mantle dynamics, mass extinctions, and paleoclimate. Zirconolite (CaZrTi2O7) is a uranium-bearing accessory mineral, found in a wide range of terrestrial and lunar rocks, that has been largely overlooked as a chronometer. In situ U-Pb geochronology of zirconolite from three dolerite intrusions in Western Australia demonstrates that it yields emplacement ages that are more precise than those obtained from coexisting zircon and baddeleyite. Dikes in the Stirling Range Formation give a zirconolite 207Pb/ 206Pb age of 1218 ± 3 Ma, indistinguishable from the less precise dates obtained from zircon (1215 ± 10 Ma) and baddeleyite (1217 ± 39 Ma) and coincident with dike emplacement in the adjacent craton margin and peak metamorphism in the Albany-Fraser orogen. Zirconolite from the 755 Ma Mundine Well dike swarm yields a 207Pb/206Pb age of 754 ± 5 Ma. Sills intruding the Proterozoic Manganese Group contain zirconolite crystals that give a 207Pb/206Pb age of 523 ± 14 Ma. Despite high U contents (550 ppm to 14,000 ppm) and greenschist facies metamorphism, zirconolite in these samples is apparently unaffected by loss of radiogenic Pb. Because of its remarkable properties for U-Pb geochronology, it may soon become the dominant tool for dating mafic igneous rocks as young as 500 Ma by ion microprobe, and thus will prove especially valuable in reconstructing Precambrian geologic history.

  11. Geochemical Database for Igneous Rocks of the Ancestral Cascades Arc - Southern Segment, California and Nevada

    USGS Publications Warehouse

    du Bray, Edward A.; John, David A.; Putirka, Keith; Cousens, Brian L.

    2009-01-01

    Volcanic rocks that form the southern segment of the Cascades magmatic arc are an important manifestation of Cenozoic subduction and associated magmatism in western North America. Until recently, these rocks had been little studied and no systematic compilation of existing composition data had been assembled. This report is a compilation of all available chemical data for igneous rocks that constitute the southern segment of the ancestral Cascades magmatic arc and complement a previously completed companion compilation that pertains to rocks that constitute the northern segment of the arc. Data for more than 2,000 samples from a diversity of sources were identified and incorporated in the database. The association between these igneous rocks and spatially and temporally associated mineral deposits is well established and suggests a probable genetic relationship. The ultimate goal of the related research is an evaluation of the time-space-compositional evolution of magmatism associated with the southern Cascades arc segment and identification of genetic associations between magmatism and mineral deposits in this region.

  12. The role of igneous and metamorphic processes in triggering mass extinctions and Earth crises

    NASA Astrophysics Data System (ADS)

    Svensen, Henrik; Planke, Sverre; Polozov, Alexander G.; Jerram, Dougal; Jones, Morgan T.

    2016-04-01

    Mass extinctions and transient climate events commonly coincide in time with the formation of Large igneous provinces (LIPs). The end-Permian event coincides with the Siberian Traps, the end-Triassic with the Central Atlantic Magmatic Event (CAMP), the Toarcian with the Karoo LIP, and the Paleocene-Eocene Thermal Maximum (PETM) with the North Atlantic Igneous Province. Although the temporal relationship between volcanism and the environmental crises has been known for decades, the geological processes linking LIPs to these environmental events are strongly debated: Explosive LIP volcanism should lead to short term cooling (not long term warming), mantle CO2 is too 13C-enriched to explain negative 13C carbon isotope excursions from sedimentary sequences, the LIP volcanism is poorly dated and apparently lasts much longer that the associated environmental events, large portions of the LIPs remain poorly explored, especially the sub-volcanic parts where sills and dikes are emplaced in sedimentary host rocks, and thus gas flux estimates from contact aureoles around sill intrusions are often poorly constrained. In this presentation, we discuss the status of LIP research with an emphasis on the sub volcanic processes. We show that potential for degassing of greenhouse gases, aerosols, and ozone destructive gases is substantial and can likely explain the triggering of both climatic events and mass extinctions.

  13. Postcollisional mafic igneous rocks record crust-mantle interaction during continental deep subduction.

    PubMed

    Zhao, Zi-Fu; Dai, Li-Qun; Zheng, Yong-Fei

    2013-12-04

    Findings of coesite and microdiamond in metamorphic rocks of supracrustal protolith led to the recognition of continental subduction to mantle depths. The crust-mantle interaction is expected to take place during subduction of the continental crust beneath the subcontinental lithospheric mantle wedge. This is recorded by postcollisional mafic igneous rocks in the Dabie-Sulu orogenic belt and its adjacent continental margin in the North China Block. These rocks exhibit the geochemical inheritance of whole-rock trace elements and Sr-Nd-Pb isotopes as well as zircon U-Pb ages and Hf-O isotopes from felsic melts derived from the subducted continental crust. Reaction of such melts with the overlying wedge peridotite would transfer the crustal signatures to the mantle sources for postcollisional mafic magmatism. Therefore, postcollisonal mafic igneous rocks above continental subduction zones are an analog to arc volcanics above oceanic subduction zones, providing an additional laboratory for the study of crust-mantle interaction at convergent plate margins.

  14. Late Triassic, arc-related, potassic igneous rocks in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Mortimer, N.

    1986-12-01

    Igneous rocks of Late Triassic age are widespread in the Cordillera of western North America and, except in Wrangellia, consist of subduction-related plutonic and volcanic suites. Many of these, including those in the Stikinia, Quesnellia, Rattlesnake Creek, and Jackson terrenes and in southern California, are clinopyroxene rich and belong to high-potassium and shoshonitic rock series, features that are generally absent from older and younger igneous rocks in the same terranes. The Late Triassic subduction-related rocks are exposed in two discontinuous belts that lie east and west of the Cache Creek terrane in Canada and correlative melange terranes farther south. Stratigraphic and structural data suggest that these belts were spatially separate magmatic arcs in Late Triassic time. Tectonic implications of this analysis include an explanation of Middle Jurassic Cordilleran deformation as the result of collision of the western with the eastern belt, absence of Late Triassic links between Stikinia and Quesnellia, disassociation of Stikinia with terranes in northwestern Nevada, and tentative correlation of the Wallowa (Seven Devils) terrane with Stikinia rather than Wrangellia. *Present address: New Zealand Geological Survey, Department of Scientific and Industrial Research, Private Bag, Dunedin, New Zealand

  15. Thermal neutron absorption cross sections for igneous rocks: Newberry Caldera, Oregon

    SciTech Connect

    Lysne, P.

    1990-01-01

    The thermal neutron absorption cross sections of geologic materials are of first-order importance to the interpretation of pulsed neutron porosity logs and of second-order importance to the interpretation of steady-state porosity logs using dual detectors. Even in the latter case, uncertainties in log response can be excessive whenever formations are encountered that possess absorption properties appreciably greater than the limestones used in most tool calibrations. These effects are of importance to logging operations directed at geothermal applications where formation vary from igneous to sedimentary and which may contain solution-deposited minerals with very large cross-section values. Most measurements of cross-section values for geologic materials have been made for hydrocarbon production applications. Hence, the specimen materials are sedimentary and clean in the sense that they are not altered by geothermal fluids. This investigation was undertaken to measure cross-section values from a sequence of igneous materials obtained from a single hole drilled in an active hydrothermal system. 3 refs., 1 fig.

  16. Plume or no plume: Emeishan Large Igneous Province in Southwest China revisited from receiver function analysis

    NASA Astrophysics Data System (ADS)

    He, Chuansong; Santosh, M.; Wu, Jianping; Chen, Xuanhua

    2014-07-01

    The Late Permian Emeishan Large Igneous Province at the western margin of the Yangtze craton and eastern Tibet is popularly regarded as the signature of mantle plume impingement onto the lithosphere. In this study, we investigate the crustal structure and upper mantle discontinuities of this region by employing H-k stacking of receiver function and depth domain receiver function. Our results image the mantle transition zone. However, no vestiges of any mantle plume upwelling in this area are recorded in our results, and the region is characterized by a largely cold domain. In contrast, our data reveal a region of lower crustal delamination that coincides with the cold mantle transition zone. We therefore suggest that the delaminated lower crustal material was recycled into the upper mantle or the mantle transition zone, turning the latter into a cold domain. The delamination of the lower crust might have also led to asthenospheric upwelling and plume-like upwelling from the mantle transition zone that generated the basalts in the Emeishan Large Igneous Province.

  17. Postcollisional mafic igneous rocks record crust-mantle interaction during continental deep subduction

    PubMed Central

    Zhao, Zi-Fu; Dai, Li-Qun; Zheng, Yong-Fei

    2013-01-01

    Findings of coesite and microdiamond in metamorphic rocks of supracrustal protolith led to the recognition of continental subduction to mantle depths. The crust-mantle interaction is expected to take place during subduction of the continental crust beneath the subcontinental lithospheric mantle wedge. This is recorded by postcollisional mafic igneous rocks in the Dabie-Sulu orogenic belt and its adjacent continental margin in the North China Block. These rocks exhibit the geochemical inheritance of whole-rock trace elements and Sr-Nd-Pb isotopes as well as zircon U-Pb ages and Hf-O isotopes from felsic melts derived from the subducted continental crust. Reaction of such melts with the overlying wedge peridotite would transfer the crustal signatures to the mantle sources for postcollisional mafic magmatism. Therefore, postcollisonal mafic igneous rocks above continental subduction zones are an analog to arc volcanics above oceanic subduction zones, providing an additional laboratory for the study of crust-mantle interaction at convergent plate margins. PMID:24301173

  18. Igneous inclusions from ordinary chondrites: High temperature cumulates and a shock melt

    NASA Technical Reports Server (NTRS)

    Sack, Richard O.; Ghiorso, Mark, S.; Wang, Ming-Sheng; Lipschutz, Michael E.

    1994-01-01

    We report microprobe, instrumental neutron activation analysis, and radiochemical neutron activation analysis data for three large igneous inclusions in the Yamato (Y-)75097, Y-793241, and Y-794046 ordinary chondrites. The inclusions in the first two chondrites are troctolitic cumulates that have undergone appreciable reactions with their hosts either during emplacement and/or cooling. Olivine-spinel Fe-Mg exchange pairs in these two inclusions record equilibration temperatures of about 710 C, and these temperatures are similar to those exhibited by mineral pairs in the Y-75097 and Y-793241 hosts. The inclusion in Y-794046 is texturally unique, consisting of fine-grained, randomly distributed olivines, coarse (approximately 2 mm) fascicular pyroxene laths, and angular pockets of maskelynite/plagioclase feldspar. The phase compositions are readily interpreted as having resulted from extremely rapid, essentially isochemical cooling to temperatures less than 1000 C of a melt with an initial temperature greater than 1670 C. We suggest that this igneous inclusion formed in-situ by shock.

  19. Three-dimensional imaging of impact of a large igneous province with a subduction zone

    NASA Astrophysics Data System (ADS)

    Reyners, Martin; Eberhart-Phillips, Donna; Upton, Phaedra; Gubbins, David

    2017-02-01

    How the thickened crust of a large igneous province on an incoming oceanic plate is accommodated at a subduction zone remains an open question. New Zealand is one of the few places to study this, as at ca. 105 Ma the ca. 35 km-thick Hikurangi Plateau impacted the Gondwana subduction zone in what is now the South Island. Here we report on results from a forty-station portable seismograph array in the southern South Island, designed to delineate the leading edge of the subducted plateau. Three-dimensional images of Vp and Vp/Vs reveal the southwestern part of the plateau was a relatively narrow salient, and the first part to be subducted. The plateau then rotated clockwise about this salient until the southern edge of the plateau was parallel to subduction strike and subduction ceased at ca. 100 Ma. Our results suggest that the global-scale plate reorganization event at 105-100 Ma was due to a cessation of subduction caused by the Hikurangi Plateau choking the Gondwana subduction zone, rather than the subduction of mid ocean ridges as previously proposed. The choking of Gondwana subduction by the plateau also led to a concentration of slab pull in the adjacent subducted oceanic crust, explaining the episode of basin opening and intraplate magmatism there that occurred at the same time. Our study underlines the havoc caused by impact of a large igneous province with a subduction zone.

  20. Ferromagnetism in ZnO doped with alkaline elements

    NASA Astrophysics Data System (ADS)

    Wang, Yiren; Piao, Jingyuan; Xin, Guozhong; Lu, Yunhao; Ao, Zhimin; Bao, Nina; Ding, Jun; Li, Sean; Yi, Jiabao

    We have observed room temperature ferromagnetism (RTFM) in ZnO doped with alkaline elements Using first-principles calculations we found the magnetization in these systems is originated from the O2p hole states around Zn vacancies. Calculations indicate that the formation energy of Zn vacancies alone is rather high while further investigation indicates the formation can be much stabilized by the alkaline dopants in the form of defect complexes. By calculating the formation energy of concerned defects and complexes, we found the role of the dopants that under a certain doping concentration: Zn vacancy, substitutional and interstitial dopants can form a defect complex, which can lower formation energy, therefore stabilizing Zn vacancies. Moreover K dopants have shown unique functions on the ferromagnetism since the substitutional K can induce magnetic moments to the system by forming partial zinc vacancy via lattice distortion. Hence K doped ZnO can be magnetic at low doping concentrations. Experimentally, Li, Na doped ZnO films and K doped ZnO nanorods with different doping levels are synthesized, RTFM can be observed in all these systems. The magnetization is found to be greatly influenced by the doping concentrations. The experimental results have shown good consistence with our theoretical calculations. Our studies can inspire the defect induced ferromagnetism as a new route for the fabrication of new diluted magnetic semiconductors.

  1. PVA in Igneous Petrology: The Rosetta Stone for Testing Mixing and Fractionation Models

    NASA Astrophysics Data System (ADS)

    Vogel, T. A.; Ehrlich, R.

    2006-05-01

    One of the major goals of igneous petrology is to evaluate the relative contributions of fractional crystallization and magma mixing (or assimilation) that produce the chemical variations within related igneous units (plutons, sills and dikes, ash-flow tuffs, lavas etc). Mixing and fractional crystallization have often been evaluated by selecting a few variables (major elements, trace elements, isotopes) and modeling the trends. EC-AFC models have been developed to include energy constraints along with selected trace elements and isotopes. Polytopic Vector Analysis (PVA) is a technique that uses all of the chemical variations (major elements and trace elements) in all the samples to determine: (1) the number of end member compositions present in the system, (2) the chemical composition of each end member, and (3) the relative contribution of each end member in each sample from the igneous unit. Each sample in the dataset is described as the sum of some fraction of each end member; therefore each sample is uniquely described by a specific amount of each of the end members. Each end member is defined in the same non negative units as the sample values. Graphical analysis of the output allows the recognition of trends either due to crystal fraction or mixing of separate magma batches (assimilation), as samples form discrete clusters or trends with different variations in end member proportions. Mixing of discrete magma batches is immediately apparent, as samples representing mixed magmas plot between the parent magmas. PVA has been used successfully to identify end members in aqueous geochemistry and petroleum. However, even though it was originally developed in part by igneous petrologists, it has not been thoroughly tested on petrologic problems. In order to evaluate PVA, we selected three igneous units in which fractionation and mixing processes had been identified: (1) glasses from Kilauea Iki drilling, which are unquestionably due to crystal fractionation; (2

  2. [Alkaline phosphatase in Amoeba proteus].

    PubMed

    Sopina, V A

    2005-01-01

    In free-living Amoeba proteus (strain B), 3 phosphatase were found after disc-electrophoresis of 10 microg of protein in PAGE and using 1-naphthyl phosphate as a substrate a pH 9.0. These phosphatases differed in their electrophoretic mobilities - "slow" (1-3 bands), "middle" (one band) and "fast" (one band). In addition to 1-naphthyl phosphate, "slow" phosphatases were able to hydrolyse 2-naphthyl phosphate and p-nitrophenyl phosphate. They were slightly activated by Mg2+, completely inhibited by 3 chelators (EDTA, EGTA and 1,10-phenanthroline), L-cysteine, sodium dodecyl sulfate and Fe2+, Zn2+ and Mn2+ (50 mM), considerably inactivated by orthovanadate, molybdate, phosphatase inhibitor cocktail 1, p-nitrophenyl phosphate, Na2HPO4, DL-dithiothreitol and urea and partly inhibited by H2O2, DL-phenylalanine, 2-mercaptoethanol, phosphatase inhibitor cocktail 2 and Ca2+. Imidazole, L-(+)-tartrate, okadaic acid, NaF and sulfhydryl reagents -p-(hydroxy-mercuri)benzoate and N-ethylmaleimide - had no influence on the activity of "slow" phosphatases. "Middle" and "fast" phosphatases, in contrast to "slow" ones, were not inactivated by 3 chelators. The "middle" phosphatase differed from the "fast" one by smaller resistance to urea, Ca2+, Mn2+, phosphates and H2O2 and greater resistance to dithiothreitol and L-(+)-tartrate. In addition, the "fast" phosphatase was inhibited by L-cysteine but the "middle" one was activated by it. Of 5 tested ions (Mg2+, Cu2+, Mn2+, Ca2+ and Zn2+), only Zn2+ reactivated "slow" phosphatases after their inactivation by EDTA treatment. The reactivation of apoenzyme was only partial (about 35 %). Thus, among phosphatases found in amoebae at pH 9.0, only "slow" ones are Zn-metalloenzymes and may be considered as alkaline phosphatases (EC 3.1.3.1). It still remains uncertain, to which particular phosphatase class "middle" and "fast" phosphatases (pH 9.0) may belong.

  3. The High Arctic Magnetic High - The Geophysical Manifestation of a Large (1.36 x 10e6 km2) and Voluminous (5-10 x 10e6 km3) Igneous Province

    NASA Astrophysics Data System (ADS)

    Saltus, Richard; Oakey, Gordon; Miller, Elizabeth; Jackson, Ruth

    2013-04-01

    comparable wavelength patterns in the complex, basin and range - style bathymetry of the Alpha and Mendeleev Ridges. Although there are many open questions regarding the development of this crustal domain, the broad geophysical expression of this feature show that it represents a substantial portion of the high Arctic crust and, as a large igneous province, a significant influx of mass and heat during its formation. Any successful model for the tectonic development of the Amerasian Basin must account for the effects of these fluxes on the strength and composition of the crust.

  4. The Martian ocean: First acid, then alkaline

    NASA Technical Reports Server (NTRS)

    Schaefer, M. W.

    1992-01-01

    In Mars' distant past, carbon dioxide and water may have been plentiful. Values of total outgassed CO2 from several to about 10 bar are consistent with present knowledge, and this amount of CO2 implies an amount of water outgassed equal to an equivalent depth of 500 to 1000 m. It is quite reasonable, therefore, to envision an early Mars in which there was a body or bodies of liquid water, perhaps in the northern plains, and a dense carbon dioxide atmosphere. Under such conditions, the pH of the water will be low, due to the dissolution of carbon dioxide in the water to form carbonic acid. This acidic water is capable of weathering the available rock quite intensely, particularly because this rock is likely to be heavily fractured (from meteorite bombardment) or even consist of fine particles (such as pyroclastic deposits). As time goes on, however, the carbon dioxide atmosphere will rapidly pass through the ocean to form carbonate deposits. As the density of the atmosphere decreases, so will the flux of carbonic acid into the ocean. Without this input of carbonic acid, the effect of the dissolved weathering products will be to increase the pH of the water. The ocean will then become alkaline. To study this process, I have developed a geochemical cycle model for the atmosphere-hydrosphere-regolith system of Mars. The treatment of geochemical cycles as complex kinetic chemical reactions has been undertaken for terrestrial systems in recent years with much success. This method is capable of elegantly handling the interactions between the simultaneous chemical reactions needed to understand such a system.

  5. Solid / solution interaction: The effect of carbonate alkalinity on adsorbed thorium

    NASA Astrophysics Data System (ADS)

    LaFlamme, Brian D.; Murray, James W.

    1987-02-01

    Elevated activities of dissolved Th have been found in Soap Lake, an alkaline lake in Eastern Washington. Dissolved 232Th ranges from less than 0.001 to 4.9 dpm/L compared to about 1.3 × 10 -5 dpm/ L in sea water. The enhanced activity in the lake coincides with an increase in carbonate alkalinity. Experiments were conducted to evaluate the effect of pH, ionic strength and carbonate alkalinity on Th adsorption on goethite. Thorium (10 -13 M total) in the presence of 5.22 mg/L α-FeOOH and 0.1 M NaNO 3 has an adsorption edge from pH 2-5. At pH 9.0 ± 0.6 the percent Th absorbed on the solid began to decrease from 100% at 100 meq/L carbonate alkalinity and exhibited no adsorption above 300 meq/L. The experimental data were modeled to obtain the intrinsic adsorption equilibrium constants for Th hydrolysis species. These adsorption constants were incorporated in the model to interpret the observed effect of carbonate alkalinity on Th adsorption. There are two main effects of the alkalinity. To a significant degree the decrease in Th adsorption is due to competition of HCO -3 and CO 2-3 ions for surface sites. Dissolved Th carbonate complexes also contribute to the increase of Th in solution.

  6. An outline of tectonic, igneous, and metamorphic events in the Goshute-Toano Range between Silver Zone Pass and White Horse Pass, Elko County, Nevada; a history of superposed contractional and extensional deformation

    USGS Publications Warehouse

    Ketner, Keith Brindley; Day, Warren C.; Elrick, Maya; Vaag, Myra K.; Zimmerman, Robert A.; Snee, Lawrence W.; Saltus, Richard W.; Repetski, John E.; Wardlaw, Bruce R.; Taylor, Michael E.; Harris, Anita G.

    1998-01-01

    Seven kinds of fault-bounded tracts are described. One of the tracts provides a good example of Mesozoic contractional folding and faulting; six exemplify various aspects of Miocene extensional faulting. Massive landslide deposits resulting from Tertiary faulting are described. Mesozoic intrusive rocks and extensive exposures of Miocene volcanic rocks are described and dated. The age ranges of stratigraphic units were based on numerous conodont collections, and ages of igneous rocks were determined by argon/argon and fission-track methods. The geologic complexity of the Goshute-Toano Range provides opportunities for many additional productive structural studies.

  7. Dating the onset and nature of the Middle Permian Emeishan large igneous province eruptions in SW China using conodont biostratigraphy and its bearing on mantle plume uplift models

    NASA Astrophysics Data System (ADS)

    Sun, Yadong; Lai, Xulong; Wignall, Paul B.; Widdowson, Mike; Ali, Jason R.; Jiang, Haishui; Wang, Wei; Yan, Chunbo; Bond, David P. G.; Védrine, Stéphanie

    2010-09-01

    The Middle Permian Emeishan large igneous province of SW China has provided the quintessential example of the phenomenon of kilometre-scale pre-eruption domal uplift associated with mantle plume impingement on the base of the lithosphere. One key line of evidence is an interpreted zone of truncation of the platform carbonates belonging to the Maokou Formation that underlies the volcanic pile. Here we test this interpretation by conodont age dating the uppermost beds of the Maokou Formation in sections from Yunnan, Sichuan, Guizhou and Guangxi provinces, which span locations from the inner part of the igneous province to several hundred kilometres beyond its margins. The results show that eruptions began in the Jinogondolella altudaensis Zone (˜ 263 Ma) of the Middle Capitanian Stage and greatly increased in extent and volume in the J. xuanhanensis Zone (˜ 262 Ma). Pre-eruption uplift was muted, and most locations within the terrain and at many locations beyond its margins witnessed platform collapse (not uplift) with deep-water facies (radiolarian cherts and submarine fans) developing in the J. altudaensis Zone. The clearest evidence for an emergence surface occurs around the margins of the province in the J. xuanhanensis Zone. This is after the initial onset of eruptions and marks either a eustatic sequence boundary or a brief pulse of tectonic uplift contemporaneous with volcanism. As with recent studies on the basal volcanic successions of the Emeishan LIP, kilometre-scale plume-related domal uplift prior to Emeishan eruptions is not supported by these data; rather a more complex interaction between plume and lithosphere with minor localized uplift and subsidence is inferred.

  8. New insights into the lowest Xuanwei Formation in eastern Yunnan Province, SW China: Implications for Emeishan large igneous province felsic tuff deposition and the cause of the end-Guadalupian mass extinction

    NASA Astrophysics Data System (ADS)

    Zhao, Lixin; Dai, Shifeng; Graham, Ian T.; Li, Xiao; Zhang, Beibei

    2016-11-01

    A previous study suggested that the lowest Xuanwei Formation is derived from weathered clastic materials of silicic composition from the Emeishan large igneous province (ELIP) based on chemostratigraphic correlations (Al2O3/TiO2 ratios) between the two. In this study, we have adopted the model that the Emeishan mantle plume commenced and terminated within a short duration and have investigated the detailed mineralogy and geochemistry of carefully sampled rocks from the lower sections of the Xuanwei Formation, eastern Yunnan Province, Southwest China. These samples are intensely argillized and characterized by high proportions of clay minerals and quartz. The samples with Al2O3/TiO2 > 7 from the lowest Xuanwei Formation have an anomalous natural gamma response and high concentrations of Nb, Ta, Zr, Hf, Th, U, Ga and REY (rare earth elements and yttrium). Our results suggest that the samples with Al2O3/TiO2 > 7 from the lowest Xuanwei Formation represent felsic volcanic tuff instead of acidic clasts as originally proposed. The lowest Xuanwei Formation and the Wangpo Bed are the felsic tuffaceous layers interbedded with clastic rocks derived from the Emeishan high-Ti basalts. Such volcanic layers most likely represent ELIP felsic tuff originated from the extrusive equivalent of Nb-Zr-enriched alkaline syenitic magmatism at the waning stage of Emeishan mantle plume activity. This study has verified the existence of extensive alkaline felsic volcanism of early Late Permian age. Such alkaline volcanism may have been catastrophic and have contributed to the end-Guadalupian mass extinction.

  9. Hydrothermal alteration and zeolitization of the Fohberg phonolite, Kaiserstuhl Volcanic Complex, Germany

    NASA Astrophysics Data System (ADS)

    Weisenberger, Tobias Björn; Spürgin, Simon; Lahaye, Yann

    2014-11-01

    The subvolcanic Fohberg phonolite (Kaiserstuhl Volcanic Complex, Germany) is an economic zeolite deposit, formed by hydrothermal alteration of primary magmatic minerals. It is mined due to the high (>40 wt%) zeolite content, which accounts for the remarkable zeolitic physicochemical properties of the ground rock. New mineralogical and geochemical studies are carried out (a) to evaluate the manifestation of hydrothermal alteration, and (b) to constrain the physical and chemical properties of the fluids, which promoted hydrothermal replacement. The alkaline intrusion is characterized by the primary mineralogy: feldspathoid minerals, K-feldspar, aegirine-augite, wollastonite, and andradite. The rare-earth elements-phase götzenite is formed during the late-stage magmatic crystallization. Fluid-induced re-equilibration of feldspathoid minerals and wollastonite caused breakdown to a set of secondary phases. Feldspathoid minerals are totally replaced by various zeolite species, calcite, and barite. Wollastonite breakdown results in the formation of various zeolites, calcite, pectolite, sepiolite, and quartz. Zeolites are formed during subsolidus hydrothermal alteration (<150 °C) under alkaline conditions. A sequence of Ca-Na-dominated zeolite species (gonnardite, thomsonite, mesolite) is followed by natrolite. The sequence reflects an increase in and decrease in of the precipitating fluid. Low radiogenic 87Sr/86Sr values indicate a local origin of the elements necessary for secondary mineral formation from primary igneous phases. In addition, fractures cut the intrusive body, which contain zeolites, followed by calcite and a variety of other silicates, carbonates, and sulfates as younger generations. Stable isotope analysis of late-fracture calcite indicates very late circulation of meteoric fluids and mobilization of organic matter from surrounding sedimentary units.

  10. Igneous phenocrystic origin of K-feldspar megacrysts in granitic rocks from the Sierra Nevada batholith

    USGS Publications Warehouse

    Moore, J.G.; Sisson, T.W.

    2008-01-01

    Study of four K-feldspar megacrystic granitic plutons and related dikes in the Sierra Nevada composite batholith indicates that the megacrysts are phenocrysts that grew in contact with granitic melt. Growth to megacrystic sizes was due to repeated replenishment of the magma bodies by fresh granitic melt that maintained temperatures above the solidus for extended time periods and that provided components necessary for K-feldspar growth. These intrusions cooled 89-83 Ma, are the youngest in the range, and represent the culminating magmatic phase of the Sierra Nevada batholith. They are the granodiorite of Topaz Lake, the Cathedral Peak Granodiorite, the Mono Creek Granite, the Whitney Granodiorite, the Johnson Granite Porphyry, and the Golden Bear Dike. Megacrysts in these igneous bodies attain 4-10 cm in length. All have sawtooth oscillatory zoning marked by varying concentration of BaO ranging generally from 3.5 to 0.5 wt%. Some of the more pronounced zones begin with resorption and channeling of the underlying zone. Layers of mineral inclusions, principally plagioclase, but also biotite, quartz, hornblende, titanite, and accessory minerals, are parallel to the BaO-delineated zones, are sorted by size along the boundaries, and have their long axes preferentially aligned parallel to the boundaries. These features indicate that the K-feldspar megacrysts grew while surrounded by melt, allowing the inclusion minerals to periodically attach themselves to the faces of the growing crystals. The temperature of growth of titanite included within the K-feldspar megacrysts is estimated by use of a Zr-in-titanite geothermometer. Megacryst-hosted titanite grains all yield temperatures typical of felsic magmas, mainly 735-760 ??C. Titanite grains in the granodiorite hosts marginal to the megacrysts range to lower growth temperatures, in some instances into the subsolidus. The limited range and igneous values of growth temperatures for megacryst-hosted titanite grains support the

  11. Building the EarthChem System for Advanced Data Management in Igneous Geochemistry

    NASA Astrophysics Data System (ADS)

    Lehnert, K.; Walker, J. D.; Carlson, R. W.; Hofmann, A. W.; Sarbas, B.

    2004-12-01

    Several mature databases of geochemical analyses for igneous rocks are now available over the Internet. The existence of these databases has revolutionized access to data for researchers and students allowing them to extract data sets customized to their specific problem from global data compilations with their desktop computer within a few minutes. Three of the database efforts - PetDB, GEOROC, and NAVDAT - have initiated a collaborative effort called EarthChem to create better and more advanced and integrated data management for igneous geochemistry. The EarthChem web site (http://www.earthchem.org/) serves as a portal to the three databases and information related to EarthChem activities. EarthChem participants agreed to establish a dialog to minimize duplication of effort and share useful tools and approaches. To initiate this dialog, a workshop was run by EarthChem in October, 2003 to discuss cyberinfrastructure needs in igneous geochemistry (workshop report available at the EarthChem site). EarthChem ran an information booth with database and visualization demonstrations at the Fall 2003 AGU meeting (and will have one in 2004) and participated in the May 2003 GERM meeting in Lyon, France where we provided the newly established Publishers' Round Table a list of minimum standards of data reporting to ease the assimilation of data into the databases. Aspects of these suggestions already have been incorporated into new data policies at Geochimica et Cosmochimica Acta and Chemical Geology (Goldstein et al. 2004), and are under study by the Geological Society of America. EarthChem presented its objectives and activities to the Solid Earth Sciences community at the Annual GSA Meeting 2003 (Lehnert et al, 2003). Future plans for EarthChem include expanding the types and amounts of data available from a single portal, giving researchers, faculty, students, and the general public the ability to search, visualize, and download geochemical and geochronological data for a

  12. Potential temperature, upwelling rate and eclogite in the formation of the North Atlantic large igneous province

    NASA Astrophysics Data System (ADS)

    Brown, E. L.; Lesher, C. E.

    2010-12-01

    The volumes and compositions of basalts generated by adiabatic decompression melting of the Earth’s mantle depend on mantle potential temperature (T_P), upwelling rate and the fertility of the mantle source. The relative importance of these factors in generating the high productivity magmatism of the Paleogene - Recent North Atlantic large igneous province (NAIP) remains controversial. Each has been proposed as a primary factor in the region. To assess the significance of these mechanisms in NAIP magmatism, we apply our forward melting model, REEBOX PRO, which simulates the melting of a heterogeneous source comprised of peridotite and eclogite lithologies. The model accounts for the thermodynamics of adiabatic decompression melting of a heterogeneous source using constraints from laboratory melting experiments. Input values of T_P and eclogite abundance are used to calculate the buoyancy of the mantle source and maximum upwelling rates. Source buoyancy constrains the maximum amount of eclogite in the mantle source that can ascend beneath the rift axis. All melts generated within the melting regime are pooled to form magmatic crust according to the residual column method. Using the model, variations in magmatic crustal thickness (from geophysics) as a function of eclogite content (from geochemistry) can be related to T_P and upwelling rate. Models with no thermal anomaly, that call on either enhanced upwelling rates due to plate separation (edge - driven convection) or the melting of abundant (> 30%) eclogite at “ambient” T_P (1325 °C), cannot generate the observed igneous crustal thicknesses around the province. Rather, elevated mantle T_P (minimum thermal anomaly ~ 85 - 195 °C) and associated buoyancy - driven upwelling are needed to explain the volume of igneous crust in the province. Involvement of eclogite, while necessary to explain the compositions of many NAIP lavas, does not significantly enhance melt production. These factors, coupled with the long

  13. The Late Cretaceous igneous rocks of Romania (Apuseni Mountains and Banat): the possible role of amphibole versus plagioclase deep fractionation in two different crustal terranes

    NASA Astrophysics Data System (ADS)

    Vander Auwera, Jacqueline; Berza, Tudor; Gesels, Julie; Dupont, Alain

    2016-04-01

    We provide new whole-rock major and trace elements as well as 87Sr/86Sr and 143Nd/144Nd isotopic data of a suite of samples collected in the Late Cretaceous volcanic and plutonic bodies of the Apuseni Mts. (Romania) that belong to the Banatitic Magmatic and Metallogenic Belt, also called the Apuseni-Banat-Timok-Srednogorie belt. The samples define a medium- to high-K calc-alkaline differentiation trend that can be predicted by a three-step fractional crystallization process which probably took place in upper crustal magma chambers. Published experimental data indicate that the parent magma (Mg# = 0.47) of the Apuseni Mts. trend could have been produced by the lower crustal differentiation of a primary (in equilibrium with a mantle source) magma. The Late Cretaceous magmatic rocks of the Apuseni Mts. and Banat display overlapping major and trace element trends except that Sr is slightly lower and Ga is higher in the Apuseni Mts. parent magma. This difference can be accounted for by fractionating plagioclase-bearing (Apuseni Mts.) or amphibole-bearing (Banat) cumulates during the lower crustal differentiation of the primary magma to the composition of the parent magma of both trends. This, together with results obtained on the Late Cretaceous igneous rocks from the Timok area in Eastern Serbia, further suggests variation of the water content of the primary magma along and across the belt. The Apuseni Mts. versus the Banat samples display different isotopic compositions that likely resulted from the assimilation of two distinct crustal contaminants, in agreement with their emplacement in two separate mega-units of Alpine Europe.

  14. Latest Mesozoic-Early Cenozoic Continental Extension and Related Alkaline Magmatism in Central Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Kadioglu, Y. K.

    2009-04-01

    The Central Anatolian crystalline complex (CACC) in Turkey includes a suite of latest Mesozoic-early Cenozoic plutonic rocks intruding the metamorphic and ophiolitic basement rocks. The intrusive rocks consist of three groups of granitoid, syenitoid, and gabbroids plutons. The granitoid units occur around the periphery of the CACC as large plutonic bodies, whereas the syenitoid assemblages crop out in the inner part of the CACC as small plutons. All the felsic plutons are crosscut by the gabbroid rocks in the region. The alkaline rocks of the CACC change in composition from nordmarkite through pulaskite to lusitanite, and are made of silica-saturated and silica-undersaturated magmas. The silica under-saturated alkaline rocks have gradual contacts with the silica-saturated alkaline rocks and constitute the main component of the alkaline rocks in the CACC. Nepheline, pseudoleucite, cancrinite, nosean, melanite and arfvedsonite are the main typical mineral compositions of the silica-undersaturated alkaline rocks. The leucite- and pseudoleucite-bearing rocks have porphyritic textures intruding the other main subunits of the alkaline rocks at high topographic elevations in the region. They are mostly composed of foid syenite, monzosyenite, monzodiorite and include rare amount of monzogabbro and foidolite. Each subunit has a transitional contact with the others and is crosscut by alkali feldspar foid syenite veins. Felsic dykes intrude the alkaline rock units and fluorite-bearing hydrothermal veins, which manifest themselves as alteration zones. The alkaline rocks have an abundance of xenolithic enclaves but lack any magma mixing-mingling produced enclaves. Normalized elemental patterns of the analyzed alkaline rocks show a slight enrichment in large ion lithophile elements (LILE) and light rare earth elements relatively to high field strength elements (HFSE) and heavy rare earth elements (HREE). The less fluid mobile, LILE and LREE concentration in the alkaline rocks

  15. Magmatic evolution of the differentiated ultramafic, alkaline and carbonatite intrusion of Vuoriyarvi (Kola Peninsula, Russia). A LA-ICP-MS study of apatite

    NASA Astrophysics Data System (ADS)

    Brassinnes, S.; Balaganskaya, E.; Demaiffe, D.

    2005-11-01

    The nature of the petrogenetic links between carbonatites and associated silicate rocks is still under discussion (i.e., [ Gittins J., Harmer R.E., 2003. Myth and reality of the carbonatite-silicate rock "association". Period di Mineral. 72, 19-26.]). In the Paleozoic Kola alkaline province (NW Russia), the carbonatites are spatially and temporally associated to ultramafic cumulates (clinopyroxenite, wehrlite and dunite) and alkaline silicate rocks of the ijolite-melteigite series [ Kogarko, L.N., 1987. Alkaline rocks of the eastern part of the Baltic Shield (Kola Peninsula). In: Fitton, J.G., and Upton, B.G.J. (eds). Alkaline igneous rocks. Geol. Soc. Special Publication 30, 531-544; Kogarko, L.N., Kononova, V.A., Orlova, M.P., Woolley, A.R., 1995. Alkaline rocks and carbonatites of the world. Part 2. Former USSR. Chapman and Hall, London, 225 pp; Verhulst, A., Balaganskya, E., Kirnarsky, Y., Demaiffe, D., 2000. Petrological and geochemical (trace elements and Sr-Nd isotopes) characteristics of the Paleozoic Kovdor ultramafic, alkaline and carbonatite intrusion (Kola Peninsula, NW Russia). Lithos 51, 1-25; Dunworth, E.A., Bell, K., 2001. The Turiy Massif, Kola Peninsula, Russia; isotopic and geochemical evidence for a multi-source evolution. J. Petrol. 42, 377-405; Woolley, A.R., 2003. Igneous silicate rocks associated with carbonatites: their diversity, relative abundances and implications for carbonatite genesis. Period. di Mineral. 72, 9-17)]. In the small (≈ 20 km 2) Vuoriyarvi massif, apatite is typically a liquidus phase during the magmatic evolution and so it can be used to test genetic relationships. Trace elements contents have been obtained for both whole rocks and apatite (by LA-ICP-MS). The apatites define a single continuous chemical evolution marked by an increase in REE and Na (belovite-type of substitution, i.e., 2Ca 2+ = Na + + REE 3+). This evolution possibly reflects a fractional crystallisation process of a single batch of isotopically

  16. 3D seismic interpretation of subsurface eruptive centers in a Permian large igneous province, Tazhong Uplift, central Tarim Basin, NW China

    NASA Astrophysics Data System (ADS)

    Yang, Jiangfeng; Zhu, Wenbin; Guan, Da; Zhu, Beibei; Yuan, Liansheng; Xiang, Xuemei; Su, Jinbao; He, Jingwen; Wu, Xinhui

    2016-11-01

    A 1445-km2 high-resolution 3D seismic reflection dataset is used to analyze the Permian large igneous province in the subsurface of the Tazhong area in the central Tarim Basin in northwestern China. Constrained by the synthetic seismograms of four wells, the top and base of the igneous rocks were identified in the seismic data. Seven large volcanic craters, each >10 km2 in area, have been discovered via the application of coherency and amplitude attributes. The thickness and volume of the igneous rocks were obtained by time-depth transformation. In the study area, all of the igneous rocks, with thicknesses from 120 to 1133 m, were formed by eruptions in the Early Permian. These events produced huge erupted volumes (178 km3) and multiple closely spaced volcanic edifices (<13 km). These features suggest that the study area may be the part of the eruptive center of the Permian igneous rocks in the Tarim Basin.

  17. Igneous and Sedimentary Compositions from Four Landing Sites on Mars from the Alpha Particle X-Ray Spectrometer (APXS)

    NASA Technical Reports Server (NTRS)

    Gellert, R.; Arvidson, R. E.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. W.; Morris, R. W.; Squyres, S. W.; VanBommel, S.; Yen, A. S.

    2016-01-01

    The APXS - supported and promoted strongly by Heinrich Waenke - on all four Mars Rovers has returned compositional data from about 1000 rocks and soil targets along the combined traverses of over 60 kilometers. Providing precise and accurate bulk chemistry with typically 16 quantified elements, the APXS is a powerful and versatile tool that when combined with the ability to traverse to key rocks and soils has provided critical information needed to understand the geologic evolution of Mars. APXS data allow comparisons among landing sites, provide ground truth for orbiters and connections back to SNC meteorites. The soils and dust are basaltic in character and represent the average Mars composition similar to Adirondack basalts from Gusev crater but with unambiguous elevated and correlated S, Cl and Zn contents. At all four landing sites the APXS found several rocks with a felsic composition. The similarity is best assessed in a logarithmic ratio plot of rock normalized to the average soil composition (Fig.1). High alkaline, Al, and low Mg, Fe, low S, Cl and Ni, Zn as well as an Fe/Mn ratio of approximately 50 indicate a likely unaltered and igneous origin. Sediments, e.g. the Burns formation, with approximately 25 wt% SO3 at Meridiani Planum have been documented over 10s of kilometers (Fig. 2). This formation is compositionally homogeneous, but showing the removal of MgSO4 and a threefold increase in Cl downhill in 2 craters. The degraded rim of the Noachian crater Endeavour resembles average Mars crust, with local Ca, Mg and Fe sulfate alteration and elevated Mn, some felsic rocks, and high Al, Si and low Fe rocks, possibly indicating clays. Unusual soils at Gusev crater in the area surrounding Home Plate include some very rich in ferric sulfate salts (up to 35 wt% SO3) and some with 90% wt% SiO2, possibly indicating fumerolic activities. Rocks in the Columbia Hills show significant signs of alteration including elevated S, Cl and Br in the abraded interior. At

  18. Intermediate range order in alkaline borate glasses

    NASA Astrophysics Data System (ADS)

    Crupi, C.; Carini, G.; Ruello, G.; D'Angelo, G.

    2016-03-01

    We describe the neutron diffraction patterns of a series of alkaline borate glasses at different metal oxide content. Strong differences are observed in the intermediate range order as a function of the specific alkaline ion and of its concentration. On these results, we propose that the first sharp diffraction peak arises from correlations of atoms of voids and show that the compositional variation of this peak intensity in alkaline borate glasses is due to changes in the distribution of void sizes within the three-dimensional network. We argue that our interpretation in terms of interstitial (empty and/or filled) voids, having different sizes, provides a general explanation for all anomalous behaviours revealed for the first sharp diffraction peak.

  19. Trace Elements in Igneous Quartz: a new Petrogenetic Tool for the Study of Granite Pegmatite Genesis

    NASA Astrophysics Data System (ADS)

    Larsen, R. B.; Larsen, R. B.; Flem, B.; Henderson, I.; Ihlen, P. M.; Ihlen, P. M.; Lahaye, Y.; Malvik, T.; Prestvik, T.

    2001-12-01

    The trace-element chemistry of quartz is rarely, if ever, considered when evaluating the origin and evolution of silica over-saturated igneous rocks. Analytical obstacles have efficiently prevented in-depth studies of the trace-element chemistry of quartz because the most interesting elements are present at the sub-ppm level and because mineral separation of quartz for traditional solution analysis is a time-consuming process. Also, igneous quartz may contain both fluid and solid inclusions that are difficult to identify during handpicking and may influence the analytical results significantly. However, in the present study we utilised in situ Laser Ablation of quartz specimens with direct introduction of the ablated material in to a double focusing sector field, ICP-MS instrument, and we developed a method that is fine-tuned for the analysis of trace elements in quartz (Flem et al., Chemical Geology, in press). Among the elements covered by the method we have focussed on substitutional trace-elements replacing Si4+ (e.g. Ti, Ge, Al, Fe and P) or elements that represent charge compensators that are accommodated in lattice vacancies or in structural channels (e.g. Li, B, K, Ca, Be). Elements analysed at low, medium and high resolutions include Li, B, Be, Al, Mn, Ge, Rb, Sr, Ba, Pb, Th, Mg, P, Ti, Ca, Cr, Fe and K. 29Si or 30Si, were used as internal standards. In the present study we evaluate the chemical evolution of quartz by comparing with the chemistry of co-existing alkali-feldspar, for which the compositional changes during igneous evolution is well known from the literature. The study includes 75 strongly zoned gadolinite-type REE-Nb-Ta rich chamber pegmatites from two major Neoproterozoic pegmatite fields in SE-Norway. Analysis of alkali-feldspar for major and accessory elements including the REE shows that the pegmatites were formed from progressively more evolved liquids through extreme fractionation of primitive granitic melts. The total concentration of

  20. Venus: chemical weathering of igneous rocks and buffering of atmospheric composition.

    PubMed

    Nozette, S; Lewis, J S

    1982-04-09

    Data from the Pioneer Venus radar mapper, combined with measurements of wind velocity and atmospheric composition, suggest that surface erosion on Venus varies with altitude. Calcium- and magnesium-rich weathering products are produced at high altitudes by gas-solid reactions with igneous minerals, then removed into the hotter lowlands by surface winds. These fine-grained weathering products may then rereact with the lower atmosphere and buffer the composition of the observed gases carbon dioxide, water vapor, sulfur dioxide, and hydrogen fluoride in some regions of the surface. This process is a plausible mechanism for the establishment in the lowlands of a calcium-rich mineral assemblage, which had previously been found necessary for the buffering of these species.