Academic literature on the topic 'Amphibolite geochemistry'

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Journal articles on the topic "Amphibolite geochemistry"

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Fonseca, Ariadne Do Carmo. "Fragmento tectónico cabo frio: aspectos de campo, petrografía e geoquímica." Anuário do Instituto de Geociências 17 (December 1, 1994): 109–31. http://dx.doi.org/10.11137/1994_0_109-131.

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The main lithological units which occur in the "Cabo Frio Tectonic Fragment" are orthogneisses and paragneisses. The orthogneisses have granitic-granodioritic-tonalitic compositions, with amphibolitic enclaves and intercalations and are cutted by granitic aplites. The paragneisses are metapelites, with intercalations of amphibolite, quartzites and calc-silicate rocks, metamorphosed in upper amphibolite facies, in intermediate pressure conditions. Geochemically, the orthogneisses correspond to a metaluminous high-K calc-alkalic series, with monzogabbro, quartz-monzodiorite and monzonite compositions. Otherwise, the petrography indicates a low-K calc-alkalic series, suggesting a pre-collisional granitoids series related to oceanic crust subduction. A divergence between the compositions obtained by the petrography and geochemistry can be the result of problems in the analyses of alkalies. The amphibolites, associated to the orthogneisses, also present calc-alkalic metaluminous character, with basaltic and andesitic compositions, suggestive of orogenic emplacement. The paragneisses show compositions varying between lithoarenite and arkoses, with peraluminous character, probably deposited in a continental are or ative continental margin environment.
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BOGDANOVA, Alyona Romanovna, Nadezhda Vladimirovna VAKHRUSHEVA, and Pavel Borisovich SHIRYAEV. "Main and rare earth elements of amphibolites of the Ray-Iz massif (Polar Urals)." NEWS of the Ural State Mining University, no. 4 (December 20, 2020): 19–27. http://dx.doi.org/10.21440/2307-2091-2020-4-19-27.

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Relevance. The Ray-Iz massif contains the Tsentralnoye chromium ore deposit and is unique in terms of variety of metamorphic rock associations. It has been studied since 1932. However, some aspects of geology and petrology in the literature are not fully covered. One of these areas is a vein series of rocks localized in ultramafic rocks. The spatial confinement of amphibolites to the Central zone of metamorphism, which is consistent with the zone of distribution of deposits and ore occurrences of chromites, determines the need for a detailed study. Purpose of work. Study of mineralogical and petrographic characteristics, as well as the geochemistry of lanthanides of amphibolites of the Ray-Iz massif (Polar Urals). Results. The study of the nature of REE distribution in rock-forming minerals made it possible to determine that the variation in the amount of REE (33–75 g/t) within one rock is associated with the quantitative content of the main minerals-concentrators. The main mineral concentrator lanthanides in garnet amphibolites is garnet, while amphibole is in garnet-free pyroxene-bearing amphibolites. Based on the results of the chemical composition of amphibole and coexisting plagioclases and amphibolite garnets, the temperature was calculated using amphiboleplagioclase by T. Holland, J. Blundy, as well as the garnet amphibolite by L. L. Perchuk geothermometers and pressure based on amphibole geobarometer by M. W. Schmidt. Conclusion. The nature of the distribution of lanthanides in the main rock-forming minerals, amphibole and garnet, has been revealed. Comparison of parameters and compositional features of amphiboles made it possible to conclude that there is a direct relationship between temperature, pressure, the sum of REE and TiO2 , as well as (La/Yb)n , in the mineral.
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Ahmid-Said, Y., and B. E. Leake. "The composition and origin of the Kef Lakhal amphibolites and associated amphibolite and olivine-rich enclaves, Edough, Annaba, NE Algeria." Mineralogical Magazine 56, no. 385 (December 1992): 459–68. http://dx.doi.org/10.1180/minmag.1992.056.385.02.

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AbstractThe Kef Lakhal amphibolitcs and associated amphibolitc and olivine-rich enclaves are dcscribcd and their major and trace element chemistry indicates that both amphibolites were evolved medium to high alumina tholeiitic basalts with talc-alkaline affinities probably formed within plate settings. The olivine-rich enclaves are disrupted periodotites of the type lherzolite-harzburgite and probably represent mantle residua after melting.
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Moazzen, Mohssen, Zohreh Salimi, Yann Rolland, Michael Bröcker, and Robab Hajialioghli. "Protolith nature and P–T evolution of Variscan metamorphic rocks from the Allahyarlu complex, NW Iran." Geological Magazine 157, no. 11 (March 18, 2020): 1853–76. http://dx.doi.org/10.1017/s0016756820000102.

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AbstractMetamorphic rocks associated with ophiolitic rocks occur on the eroded surface of a NW–SE-trending anticline in the Allahyarlu area, NW Iran, between the Caucasus and Zagros orogenic belts. Metapelitic rocks consist mainly of quartz, muscovite chlorite, altered biotite and garnet. S1 is the pervasive schistosity, wrapping garnet, which is folded by the second schistosity (S2). The amphibolite records only one phase of deformation as the main lineation. The rocks experienced metamorphism up to the amphibolite facies, then overprinted by greenschist facies condition. Thermobarometry indicates an average pressure of c. 5 kbar and an average temperature of c. 600 °C for the amphibolite facies metamorphism, corresponding to a ∼33 °C km−1 geothermal gradient in response to a thick magmatic arc setting. Greenschist facies metamorphism shows re-equilibration of the rocks during exhumation. Amphibolites whole rock geochemistry shows trace elements patterns similar to both island arc and back-arc basin basalts, suggesting that the protolith-forming magma of the amphibolites was enriched at shallow to medium depth of a subduction system. Negative Nb anomaly and slight enrichment in light rare earth elements (LREE) and large-ion lithophile elements (LILE) of the amphibolites indicate arc-related magmatism for their protolith and a back-arc sialic setting for their formation. 40Ar–39Ar dating on muscovite separated from two gneiss samples, and hornblende separated from three amphibolite samples, documents a Variscan (326–334 Ma) age. The magmatic and metamorphic rock association of the Allahyarlu area suggests the existence of an active continental margin arc during the Variscan orogeny, without clear evidence for a continental collision.
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Bogoch, R., and M. Shirav. "Carbonate nodules of probable stromatolitic origin in amphibolite from the Neoproterozoic terrain of southern Israel." Mineralogical Magazine 68, no. 4 (August 2004): 579–89. http://dx.doi.org/10.1180/0026461046840213.

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AbstractSeveral small bodies of massive to banded amphibolite occur within plagioclase-quartz-biotite hornblende gneiss at or close to its boundary with a quartz diorite pluton in the Neoproterozoic terrain of southern Israel. Entrapped within the amphibolite are nodules consisting mainly of calcite+talc, and rare banded marble. Remnant laminae and certain geochemical features such as the negative Ce anomaly and depleted δ13C of the nodules sugggest that they initially formed as stromatolites. The local geological setting of the amphibolites together with the presence of the enclosed meta-carbonates favoured an origin as sediments, although some of the geochemical data point to a basaltic precursor and some of the carbonates have a puzzlingly high (>1000 ppm) Ni content. The origin of the amphibolites is thus enigmatic.
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Moyen, Jean-François, and Gordon R. Watt. "Pre-Nagssugtoqidian crustal evolution in West Greenland: geology, geochemistry and deformation of supracrustal and granitic rocks north-east of Kangaatsiaq." Geological Survey of Denmark and Greenland (GEUS) Bulletin 11 (December 5, 2006): 33–52. http://dx.doi.org/10.34194/geusb.v11.4915.

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The area north-east of Kangaatsiaq features polyphase grey orthogneisses, supracrustal rocks and Kangaatsiaq granite exposed within a WSW–ENE-trending synform. The supracrustal rocks are comprised of garnet-bearing metapelites, layered amphibolites and layered, likewise grey biotite paragneisses. Their association and geochemical compositions are consistent with a metamorphosed volcano-sedimentary basin (containing both tholeiitic and calc-alkali lavas) and is similar to other Archaean greenstone belts. The Kangaatsiaq granite forms a 15 × 3 km flat, subconcordant body of deformed, pink, porphyritic granite occupying the core of the supracrustal synform, and is demonstrably intrusive into the amphibolites. The granite displays a pronounced linear fabric (L or L > S). The post-granite deformation developed under lower amphibolite facies conditions (400 ± 50°C), and is characterised by a regular, NE–SW-trending subhorizontal lineation and an associated irregular foliation, whose poles define a great circle; together they are indicative of highly constrictional strain. The existence of a pre-granite event is attested by early isoclinal folds and a foliation within the amphibolites that is not present in the granite, and by the fact that the granite cuts earlier structures in the supracrustal rocks. This early event, preserved only in quartz-free lithologies, resulted in high-temperature fabrics being developed under upper amphibolite to granulite facies conditions.
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Soret, Mathieu, Philippe Agard, Benoît Ildefonse, Benoît Dubacq, Cécile Prigent, and Claudio Rosenberg. "Deformation mechanisms in mafic amphibolites and granulites: record from the Semail metamorphic sole during subduction infancy." Solid Earth 10, no. 5 (October 23, 2019): 1733–55. http://dx.doi.org/10.5194/se-10-1733-2019.

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Abstract. This study sheds light on the deformation mechanisms of subducted mafic rocks metamorphosed at amphibolite and granulite facies conditions and on their importance for strain accommodation and localization at the top of the slab during subduction infancy. These rocks, namely metamorphic soles, are oceanic slivers stripped from the downgoing slab and accreted below the upper plate mantle wedge during the first million years of intraoceanic subduction, when the subduction interface is still warm. Their formation and intense deformation (i.e., shear strain ≥5) attest to a systematic and transient coupling between the plates over a restricted time span of ∼1 Myr and specific rheological conditions. Combining microstructural analyses with mineral chemistry constrains grain-scale deformation mechanisms and the rheology of amphibole and amphibolites along the plate interface during early subduction dynamics, as well as the interplay between brittle and ductile deformation, water activity, mineral change, grain size reduction and phase mixing. Results indicate that increasing pressure and temperature conditions and slab dehydration (from amphibolite to granulite facies) lead to the nucleation of mechanically strong phases (garnet, clinopyroxene and amphibole) and rock hardening. Peak conditions (850 ∘C and 1 GPa) coincide with a pervasive stage of brittle deformation which enables strain localization in the top of the mafic slab, and therefore possibly the unit detachment from the slab. In contrast, during early exhumation and cooling (from ∼850 down to ∼700 ∘C and 0.7 GPa), the garnet–clinopyroxene-bearing amphibolite experiences extensive retrogression (and fluid ingression) and significant strain weakening essentially accommodated in the dissolution–precipitation creep regime including heterogeneous nucleation of fine-grained materials and the activation of grain boundary sliding processes. This deformation mechanism is closely assisted with continuous fluid-driven fracturing throughout the exhumed amphibolite, which contributes to fluid channelization within the amphibolites. These mechanical transitions, coeval with detachment and early exhumation of the high-temperature (HT) metamorphic soles, therefore controlled the viscosity contrast and mechanical coupling across the plate interface during subduction infancy, between the top of the slab and the overlying peridotites. Our findings may thus apply to other geodynamic environments where similar temperatures, lithologies, fluid circulation and mechanical coupling between mafic rocks and peridotites prevail, such as in mature warm subduction zones (e.g., Nankai, Cascadia), in lower continental crust shear zones and oceanic detachments.
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Dolníček, Zdeněk, and Jana Ulmanová. "Chemické složení granátů v amfibolitech z lomu Libodřice u Kolína (kutnohorské krystalinikum, Česká republika)." Bulletin Mineralogie Petrologie 30, no. 2 (2022): 205–13. http://dx.doi.org/10.46861/bmp.30.205.

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Three types of garnet-bearing lithologies sampled in the quarry Libodřice near Kolín (Kutná Hora Crystalline Complex, Czech Republic) were studied by means of BSE imaging and electron microprobe analyses. The first type is represented by common garnetic amphibolites, in which garnet forms isolated millimetre-sized porphyroblasts containing numerous inclusions of minerals of the host amphibolite matrix (plagioclase, epidote, amphibole, sulphides). The composition of weakly zoned garnet is Alm55-56Grs30-37Sps1-5Prp5-12Adr0-3. Second type is garnetite, composed of garnet+quartz or garnet+epidote, in both cases with minor amphibole, which forms rare centimetre-thick bands in amphibolites. The garnetite garnet is distinctly zoned, with cores enriched in spessartine component (Alm42-51Grs29-38Sps11-16 Prp2-8Adr0-3Ti-Grs0-1F-Kat0-1) and margins depleted in Sps and enriched in pyrope component (Alm49-54Grs28-35Sps4-10 Prp7-11Adr0-1F-Kat0-1). The origin of the pronounced enrichment in Mn is interpreted in terms of specific chemical composition of protolith of this garnetite, which was likely represented by a chemogenic precipitate rich in Si, Al, Fe, Mn and in places possibly also Ca. The last found garnetiferous lithology is represented by zoned reaction skarn rimming small xenoliths of calcitic marbles enclosed in amphibolites. The garnet-rich zone of the skarn is dominated by chemically homogeneous grossularite with composition Grs73-76Adr16-21Alm2-5Ti-Grs1-2Sps1F-Kat1Gol0-1.
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Shiraishi, Kazuyuki, Takanobu Oba, Morihisa Suzuki, and Ken’ichi Ishikawa. "Subsilicic magnesian potassium-hastingsite from the Prince Olav Coast, East Antarctica." Mineralogical Magazine 58, no. 393 (December 1994): 621–27. http://dx.doi.org/10.1180/minmag.1994.058.393.11.

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AbstractTwo subsilicic magnesian potassium-hastingsites (4.55 and 4.34 wt.% K2O) and one magnesian potassium-hastingsite occur in calc-silicate pods in well-layered gneisses from the transitional amphibolite- and granulite-facies terrain of a Cambrian metamorphic complex, East Antarctica. Subsilicic magnesian potassium-hastingsite is the most K-rich Ca-amphibole yet reported:
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Belic, Maximilian, Christoph A. Hauzenberger, and Yunpeng Dong. "Multistage Metamorphic Evolution of Retrograded Eclogites from the Songshugou Complex, Qinling Orogenic Belt, China." Journal of Petrology 60, no. 11 (November 1, 2019): 2201–26. http://dx.doi.org/10.1093/petrology/egaa007.

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Abstract The Qinling Orogenic Belt is one of the major collisional orogens in eastern Asia and marks the boundary between the North China Craton and South China Craton. The Songshugou complex is the largest basic to ultrabasic body to be found in the North Qinling Belt, and was emplaced as a lens-shaped body at the southern margin of the Qinling Group. A detailed petrological investigation of garnet amphibolite, augen amphibolite and well-foliated amphibolite together with garnet zoning patterns of major and trace elements, inclusions in garnet, and thermodynamic modelling indicate a multistage metamorphic history. Garnets clearly show characteristics of discontinuous growth, as they display optically light-colored snowball-textured cores surrounded by a darker mantle with few inclusions as well as chemically a sudden increase in grossular and decrease in almandine components. A partly resorbed rim is not recognized optically but mineral inclusions and a discontinuous chemical composition of garnet are proof of this third garnet growth stage. Rare earth element distribution patterns of garnet also show clear evidence for discontinuous growth and allow us to identify the reactions responsible for garnet growth. Garnet core compositions as well as amphibole inclusions allow us to constrain a P–T window where this rock equilibrated in a first stage. Calculated pseudosections and the application of the garnet–amphibole thermometer indicate an upper amphibolite- to lower granulite-facies metamorphic episode at 630–740 °C and 0·7–0·9 GPa. The presence of relict omphacite as well as a discontinuously grown garnet mantle with rutile inclusions clearly places the peak metamorphic stage in the eclogite facies. Garnet (XGrs, XAlm, XPrp) and omphacite isopleths (XMg, XNa) constrain this event at 1·7–2·1 GPa and 570–650 °C. Consistent temperatures of 500–650 °C were also determined by clinopyroxene–garnet geothermobarometry for this event. Growth of an outermost rim as well as different stages of garnet breakdown to plagioclase + amphibole coronae and the nearly complete replacement of former omphacite by a variety of symplectites point to an intricate retrograde P–T path. In more strongly retrograded samples plagioclase + amphibole ± quartz pseudomorphs entirely replace former garnet grains. Certain coronae around garnets and symplectites also contain prehnite and pumpellyite, which formed during a late retrograde stage or during a different event at very low P–T conditions (250–350 °C). Based on the detailed petrological study, we favour a multistage metamorphic history of the Songshugou metabasic rocks. The age of the eclogite-facies metamorphic event must be related to the deep subduction of the Songshugou complex during the early Paleozoic, although the age of garnet core growth remains enigmatic. The development of garnet cores indicates an upper amphibolite-facies regional metamorphic overprint succeeded by an eclogite-facies event around 500 Ma and subsequent retrogression seen in replacement of garnet and formation of symplectite. The latest imprint evidenced by prehnite and pumpellyite may be the result of fluid infiltration during the fading orogenic phase or represents a low-temperature overprint by a later process, probably related to the uplift of the North Qinling terrane at around 420 Ma.
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Dissertations / Theses on the topic "Amphibolite geochemistry"

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Wang, Weiliang. "Amphibolites of the Bangong-Nujiang suture zone, Tibet." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41897237.

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Guilmette, Carl. "Petrology, geochemistry and geochronology of highly foliated amphibolites from the ophiolitic mélange beneath the Yarlung Zangbo ophiolites, Xigaze area, Tibet : geodynamical implications." Master's thesis, Université Laval, 2005. http://hdl.handle.net/20.500.11794/18102.

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On retrouve localement des amphibolites fortement foliées dans le mélange ophiolitique sous les massifs ophiolitiques de la Zone de Suture du Yarlung Zangbo (ZSYZ). Ces blocs représentent la partie supérieure d’une semelle métamorphique démembrée. La géochimie des amphibolites (La/Yb = 0.65-0.97, Ta/Th = 0.33-0.65) est similaire à celle des roches mafiques provenant de l’ophiolite, suggérant une origine dans le même bassin d’arrière-arc. Le métamorphisme de haut grade (P=14 kbars, T= 800°C) subit par les amphibolites suggère un enfouissement pendant la naissance d’une subduction. Les âges voisins des amphibolites et de la croûte ophiolitique (121-130 vs 120±10 et 126 Ma, respectivement) suggèrent que la naissance de la subduction s’est déroulée dans le bassin arrière-arc Néo-Téthysien. Un tel événement n’avait pas encore été rapporté. La présence de dikes et le métasomatisme tardif responsable de la cristallisation de préhnite pourraient indiquer la subduction d’un centre magmatique. La composition en isotopes stables du fluide responsable confirmerait une telle hypothèse.
Blocks of highly foliated amphibolites are locally found within the serpentinite matrix mélange underlying the Yarlung Zangbo ophiolites near Bainang and Buma, Xigaze area, Yarlung Zangbo Suture Zone (YZSZ), Tibet. The mélange is thought to be the result of the tectonic dismemberment of the base of the ophiolitic napes during its obduction over the Indian passive margin, circa 50 Ma. Prior to dismemberment, amphibolites were probably parts of a coherent dynamothermal sole, as observed at the base of many ophiolites. Sampled amphibolites can be subdivided in three groups: garnet, banded and common amphibolites. Medium-grained garnet amphibolites contain the assemblage A) Hb+CPX+Gt+Pl±Rt and B) Gt+Hb+Pl (corona assemblage). Fine to medium-grained banded amphibolites contain the assemblage C) Hb+CPX+Pl+Ep±Sp+Qtz+Ap. Fine-grained common amphibolites contain facies D) Hb+Pl±Ep+Ap+Sp. In all assemblages, plagioclase is pseudomorphosed by an albite-prehnite simplectite. Retrograde cataclastic veins contain the assemblage E) Ab+Pr±Ch+Ep. The geochemistry of the garnet, banded and common amphibolites is very similar to the geochemistry of other mafic blocks in the mélange and of mafic igneous rocks within the ophiolitic massifs. When compared to MORBs, light depletion of LREE (La/Yb = 0.65-0.97) and mild HFSE depletion (Ta/Th = 0.33-0.65) would suggest a mixing between the IAT and MORB sources, as seen in back-arc basins and nascent intra-oceanic arcs. The amphibolites were buried at the inception of a subduction within the back-arc to peak metamorphism conditions of 11-14 kbars and ~800 °C. Ar/Ar analysis of amphiboles revealed a metamorphic age of 121-130 Ma, which is synchronous with ages obtained from the overlying ophiolites. Overlapping in ophiolite-sole age relationship reveals inception of the subduction near or at the spreading center from which originated the ophiolite. Subduction of a buoyant body could explain heterogeneous coronitization of pyrope-rich (up to 35 %) garnet by Al-Tschermakites (Al2O3 up to 21 wt %) at high-pressures. After exhumation, amphibolites were injected by very fine-grained diabasic dykes and were subject to percolation of a prehnite-precipitating fluid. Oxygen stable isotopes suggest that a magmatic fluid is responsible for prehnite precipitation. The magmatic and metamorphic history of the dynamothermal sole and field relationships with adjacent units seem to indicate that most of Neo-Tethys oceanic domain was subducted along this new Late Cretaceous subduction zone.
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Wang, Weiliang, and 王維亮. "Amphibolites of the Bangong-Nujiang suture zone, Tibet." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41897237.

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Fernandez, Laure. "Etude géochimique et géochronologique d'un massif basique et ultrabasique des zones internes de la chaîne des Maghrébides (Edough, NE Algégrie) : contraintes sur l'évolution de la Méditerranée Occidentale au Cénozoïque." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS102/document.

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Le massif de l’Edough représente le massif cristallin le plus oriental de la chaîne des Maghrébides. Ce massif, peu étudié, est cependant particulièrement intéressant car il permet de faire le lien avec les autres segments de la chaîne Alpine Péri-Méditerranéenne. Il se présente sous la forme d’un dôme métamorphique principalement constitué de gneiss et migmatites contenant en son cœur des amphibolites à grenat et des métapéridotites (péridotites de Sidi Mohamed). Au Nord, il est chevauché par l’unité de Kef Lakhal composée d’amphibolites massives, qui sont séparées du dôme par une unité de mélange contenant des lithologies de nature très variée. Trois de ces unités ont été étudiées: les péridotites de Sidi Mohamed, l’unité de mélange, et l'unité de Kef Lakhal. Les objectifs de ce doctorat consistent à: i) caractériser ces différentes unités en terme de source, processus enregistrés et évolution, ii) contraindre l'âge de ces unités et, éventuellement, l'âge du/des métamorphisme(s) enregistré(s), iii) replacer ces différentes unités dans un contexte global de la géodynamique du bassin Méditerranéen au cours du Cénozoïque. Ainsi une approche combinée couplant pétrologie, géochimie et géochronologie a été réalisée sur un échantillonnage prélevé en 2012, et principalement focalisé sur les lithologies basiques et ultra-basiques ainsi que sur les zones de contact entre ces trois unités. La méthodologie mise en oeuvre consiste, à la fois, en des analyses in situ (éléments majeurs et traces, géochronologie U-Pb, isotopes Hf) et des mesures sur roches totale et fractions minérales (éléments majeur et traces, géochronologie Ar-Ar et isotopes Sr-Nd-Pb-Hf). Dans la zone de Sidi Mohamed, les amphibolites à grenat proviennent d’un manteau similaire à celui des témoins retrouvés au niveau du bloc d’Alboran et enregistrent un évènement métamorphique à c. 18 Ma. Les roches ultramafiques situées au cœur du dôme possèdent des signatures isotopiques de type manteau sous-continental avec une influence de processus de subduction et une empreinte géochimique plus tardive liée aux processus d’exhumation. L’unité de mélange est interprétée comme une marge passive Permo-Carbonifère. Les amphibolites proviennent d’un manteau modifié par une ancienne subduction. Cette unité de mélange contient des reliques métamorphisées sous conditions d’Ultra-Haute Pression marquées notamment, par la présence de diamants inclus dans un méga-cristal de grenat dont le protolithe est de type N-MORB. Le stade prograde de l'évènement UHP a été daté à c. 32 Ma et l'exhumation puis le charriage sur le socle de l’Edough se produisent à c. 21 Ma. L’unité amphibolitique de Kef Lakhal présente des signatures de type croute océanique N-MORB et représenterait un vestige de la Téthys entré en subduction puis exhumé à c. 21 Ma. Nous proposons que le massif de l’Edough représente la marge passive Nord-Africaine d’âge Permo-Carbonifère sur laquelle un fragment de croûte océanique Téthysienne a été charriée au cours du Miocène. L’exhumation du massif se produit en deux stades dont le premier à ~21 Ma est suivi par la formation d’un Metamorphic Core Complex à partir de 18 Ma. Nous relions ces processus rapides à des mouvements de la fosse de subduction et du panneau plongeant
The Edough massif is the Easternmost crystalline massif of the Maghrebide belt. This area presents strong similarities with the internal zones of the Peri-Mediterranean Alpine belt but its evolution stillremains poorly constrained. Edough can be approximated as a metamorphic dome of gneisses and migmatites containing garnet amphibolite and metaperidotites of Sidi Mohamed in its core. In the North, the dome is overlain by a nappe stack constituted by a “melange” unit composed of various lithologies and, upward, by the Kef Lakhal massive amphibolites of oceanic origin. This work is focused on three units containing mafic and ultramafic lithologies i.e. the Sidi Mohamed peridotites, the “melange” unit and the Kef Lakhal amphibolites. The aim of this Ph.D. work is to characterize all three units, to determine their relationships and establish the timing of the main events identified. We chose a combined geochronological-geochemical approach using in situ analyses (major and trace elements, U-Pb geochronology and Hf isotopes on accessory minerals) and bulk analyses on whole rock/mineral fraction (major and trace elements, Ar-Ar geochronology and Sr-Nd-Pb-Hf isotopes). We show that the Sidi Mohamed mafic rocks display an affinity with the Alboran mantle. The mantle rocks from Sidi Mohamed display affinities with a subcontinental mantle influenced by subduction processes and late metamorphism at crustal levels. The melange unit is interpreted as a Permo-Carboniferous passive margin. The amphibolite lenses in the mélange unit originate from a mantle modified by subduction processes. This unit contains relics of Ultra-High Pressure rocks as evidenced by the occurrence of diamonds in a megacrystal of garnet showing oceanic affinities. These ultra-high pressure rocks document a prograde stage at ~32 Ma and exhumation to lower crustal levels at ~21 Ma. The Kef Lakhal unit displays oceanic crust-like signatures and characteristics of fluid induced signatures. We interpret the Kef Lakhal amphibolites as a shallow subducted Tethys fragment, which was exhumed at 21 Ma. We propose that the Edough massif represents the Permo-carboniferous passive margin of Africa basement onto which a fragment of the Tethys Ocean was thrusted. The whole massif was finally exhumed as a metamorphic core complex at 18 Ma and experienced fast cooling until ~16 Ma. We relate this fast processes to the interplay between trench and slab movements
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Dalpé, Claude. "Trace element partitioning between amphibole and basaltic melt." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34939.

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The effects of composition, pressure and oxygen fugacity on partition coefficients between amphibole and hydrous basaltic melt were studied at 1.5 to 2.5 GPa and 1000 to 1130°C. Partition coefficients (D i = concentration of element i in amphibole/concentration of i in melt) of large-ion-lithophile elements (LILE: Rb, Sr, Ba), high-field-strength elements (HFSE: Y, Zr, Nb, Ta, Hf), and rare-earth elements (REE: La to Lu) were determined between amphiboles and coexisting quenched melts created by partial crystallization of seven different starting compositions in a piston-cylinder high-pressure apparatus. Trace elements were analyzed by laser-ablation, microprobe inductively coupled plasma-mass spectrometer (LAM-ICP-MS). The effects of premium, temperature and oxygen fugacity on the partition coefficients are minor, but statistically measurable. Amphibole composition affects partitioning of these trace elements by a maximum factor of 3.5 in the range of pressures and temperatures studied with an oxygen fugacity range of 2 orders of magnitude above and below nickel-nickel oxide buffer. Experiments specifically investigating the role of Ti demonstrate that a positive correlation exists between amphibole VITi 4+ content and DBa, D Sr, DTa, D Zr, DLa, DCe, DPr, and DNd. Increasing pressure from 1.5 GPa, to 2.2 or 2.5 GPa (depending upon composition) increases DLILE, but decreases DHFSE and DREE. Raising the oxygen fugacity at 1.5 or 2.5 GPa by 3 orders of magnitude increases DRb, DBa, DLa, and D Nd, whereas DTi, D Hf, and DZr decrease; however, the maximum difference between partition coefficients measured at low and high oxygen fugacities is only a factor of 1.7. All of the effects of composition, pressure, and oxygen fugacity reflect the control of crystal chemistry on the partitioning of trace elements between amphibole and basaltic melt. No effects of melt composition were discerned in this study. The measured partition coefficients were used to investigate tr
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Kuyumjian, Raul Minas. "The geochemistry and tectonic significance of amphibolites from the Chapada sequence, Central Brazil." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47522.

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Injoque-Espinoza, J. "Geochemistry of the Cu-Fe-amphibole skarn deposits of the Peruvian coast." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355424.

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CHWAE, Ueechan, Izumi KAJIZUKA, Daniel J. DUNKLEY, and Kazuhiro SUZUKI. "A preliminary report on the geochemistry of amphibolites from the Chuncheon area in the Gyeonggi massif, Korea." Dept. of Earth and Planetary Sciences, Nagoya University, 2009. http://hdl.handle.net/2237/14731.

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Rosatelli, Gianluigi. "The petrogenesis of carbonitic rocks and their relation to mantle amphibole and carbonate as exemplified in contrasting volcanoes from Vulture, Italy and Rangwa, East Africa." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252281.

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Collins, Nathan. "Geochemical Systematics Among Amphibolitic Rocks in the Central Blue Ridge Province of southwestern North Carolina." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3045.

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ABSTRACT The Central Blue Ridge sub-province of the southern Appalachian Mountains preserves an unique and complex geologic history. The Cartoogechaye terrane is the westernmost terrane of the Central Blue Ridge sub-province, and is characterized by extensive olistostromal sequences, including mafic-ultramafic massifs, isolated mafic units, and block-in-matrix structures of varying scales. This study investigates the genetic and tectonic relationships, and regional chemical and metamorphic trends of the amphibolitic rocks entrained within units of the Cartoogechaye and nearby terranes, toward constraining the origins of these regional sequences, and examining the rationale for the current Blue Ridge terrane designations. A distinct compositional variation exists between the northern and southern portions of the Cartoogechaye terrane, evident in the mafic rocks of the terrane. The amphibolite blocks and mega-blocks of the Willets-Addie mafic unit, in the northeastern portion of the Cartoogechaye terrane, indicate igneous rock protoliths of a calc-alkaline composition that are different from the mafic-origin amphibolitic massifs of the southwestern Cartoogechaye terrane (Ryan et al., 2005). Amphibolitic blocks of the Tathams Creek/Sylva area, immediately southwest of the Willets-Addie study site, show rare earth element systematics indistinguishable from the more mafic rocks in the Willets-Addie area, albeit with some chemical variation related most likely to variable migmatization of the rocks regionally. Mafic rocks in the adjoining Mars Hill terrane to the northwest show similar chemical trends, even though the Mars Hill terrane is recognized as different from the Cartoogechaye terrane, based on dating results from enclosing granitiods and migmatitic segregations. In the southwestern Cartoogechaye terrane, the Carroll Knob mafic complex preserves chemical signatures suggestive of ocean crustal origins, similar to the Buck Creek mafic-ultramafic suite (Berger et al. 2001, Peterson et al., 2009). However, the amphibolites in the Carroll Knob complex indicate pyroxene-rich cumulate and gabbroic protoliths consistent with an active oceanic magma system undergoing continuous magmatic replenishment and crystallization. West of the Carroll Knob complex, the Kimsey Bald mafic body includes amphibolites with protoliths comparable to the MORB-like, high-Ti amphibolites of the Buck Creek suite. The few amphibolite samples from the Lake Chatuge complex examined in this study also shows ocean crustal affinities, similar to those in the Buck Creek, Kimsey Bald, and Carroll Knob complexes. The chemical distinctions among these amphibolite suites, and the differences in the inferred crustal ages among their enclosing crustal units point to a possible boundary between the northern and southern regions of the Cartoogechaye terrane, one related either to likely crustal protoliths, or to a change in tectonic environment. The varied types of blocks comprising the Tathams Creek and associated Cartoogechaye units may indicate a transitional zone between the upper plate-derived accretionary sequences observed to the northeast and dominantly lower oceanic plate lithologies exposed in the southwestern extent of the terrane.
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Books on the topic "Amphibolite geochemistry"

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Awdankiewicz, Honorata. Petrologia i geochemia metabazytów masywu Niedźwiedzia na bloku przedsudeckim: The petrology and geochemistry of the metabasites of the Niedźwiedź Massif in the Fore-Sudetic Block. Warszawa: Państwowy Instytut Geologiczny, 2008.

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Laurs, Brendan M. Emerald mineralization and amphibolite wall-rock alteration at the Khaltaro pegmatite-hydrothermal vein system, Haramosh Mountains, Northern Pakistan. 1995.

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Book chapters on the topic "Amphibolite geochemistry"

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Cummings, Michael L., and William R. McCulloch. "Geochemistry and origin of amphibolite and ultramafic rocks, Branham Lakes area, Tobacco Root Mountains, southwestern Montana." In Proceedings of the International Conferences on Basement Tectonics, 323–40. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-1614-5_22.

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Olajide-Kayode, Jerry, Olugbenga Okunlola, and Akinade Olatunji. "Geochemistry and Mineral Chemistry of Amphibolites in Parts of the Proterozoic Ilesa Schist Belt, Southwestern Nigeria." In Advances in Science, Technology & Innovation, 333–35. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-72547-1_71.

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Shimabukuro, David H., and Claire Battistella. "Ligurian hyperextended continental margin preserved in an ophiolitic block at Timpa di Pietrasasso, Calabrian Arc, southern Italy." In From the Guajira Desert to the Apennines, and from Mediterranean Microplates to the Mexican Killer Asteroid: Honoring the Career of Walter Alvarez. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2557(10).

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ABSTRACT The Cenozoic accretionary complex in the Calabrian Arc, southern Italy, contains hectometric- to kilometric-scale exposures of basalt, gabbro, and serpentinite that have been interpreted as dismembered fragments of Alpine Tethys ocean crust because of their incomplete nature with respect to the traditional view of a complete ophiolite sequence. We present new geologic mapping, geochemistry, and geochronology of one of these units at Timpa di Pietrasasso near the town of Terranova di Pollino in the Basilicata region that exposes Jurassic Tethyan pillow basalt and chert that are separated from gabbro and serpentinite by a fault. The gabbro in the footwall is Permian in age, indicated by U-Pb zircon ages of 284 ± 6 Ma, 293 ± 6 Ma, and 295 ± 4 Ma, linking it to gabbros that underplated continental crust after the Permo-Carboniferous Variscan Orogeny. The gabbro first underwent amphibolite-facies metamorphism, then developed a greenschist-facies mylonitic foliation near the fault surface that is crosscut by undeformed Jurassic-aged dikes of Tethyan origin, indicating that deformation is early Tethyan or pre-Tethyan in age. The underlying serpentinite is tectonically interleaved with blocks of Variscan lower crust, indicating that the missing upper plate of the extensional detachment complex was continental in origin. These features indicate that the Timpa di Pietrasasso unit preserves a low-angle detachment fault that developed in a hyperextended continental margin of the Alpine Tethys.
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Amgaa, Tsolmon, Dieter Mader, Wolf Uwe Reimold, and Christian Koeberl. "Tabun Khara Obo impact crater, Mongolia: Geophysics, geology, petrography, and geochemistry." In Large Meteorite Impacts and Planetary Evolution VI. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2550(04).

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ABSTRACT Tabun Khara Obo is the only currently known impact crater in Mongolia. The crater is centered at 44°07′50″N and 109°39′20″E in southeastern Mongolia. Tabun Khara Obo is a 1.3-km-diameter, simple bowl-shaped structure that is well visible in topography and clearly visible on remote-sensing images. The crater is located on a flat, elevated plateau composed of Carboniferous arc-related volcanic and volcanosedimentary rocks metamorphosed to upper amphibolite to greenschist facies (volcaniclastic sandstones, metagraywacke, quartz-feldspar–mica schist, and other schistose sedimentary rocks). Some geophysical data exist for the Tabun Khara Obo structure. The gravity data correlate well with topography. The −2.5–3 mGal anomaly is similar to that of other, similarly sized impact craters. A weak magnetic low over the crater area may be attributed to impact disruption of the regional trend. The Tabun Khara Obo crater is slightly oval in shape and is elongated perpendicular to the regional lithological and foliation trend in a northeasterly direction. This may be a result of crater modification, when rocks of the crater rim preferentially slumped along fracture planes parallel to the regional structural trend. Radial and tangential faults and fractures occur abundantly along the periphery of the crater. Breccias occur along the crater periphery as well, mostly in the E-NE parts of the structure. Monomict breccias form narrow (<1 m) lenses, and polymict breccias cover the outer flank of the eastern crater rim. While geophysical and morphological data are consistent with expectations for an impact crater, no diagnostic evidence for shock metamorphism, such as planar deformation features or shatter cones, was demonstrated by earlier authors. As it is commonly difficult to find convincing impact evidence at small craters, we carried out further geological and geophysical work in 2005–2007 and drilling in 2007–2008. Surface mapping and sampling did not reveal structural, mineralogical, or geochemical evidence for an impact origin. In 2008, we drilled into the center of the crater to a maximum depth of 206 m, with 135 m of core recovery. From the top, the core consists of 3 m of eolian sand, 137 m of lake deposits (mud, evaporites), 34 m of lake deposits (gypsum with carbonate and mud), 11 m of polymict breccia (with greenschist and gneiss clasts), and 19 m of monomict breccia (brecciated quartz-feldspar–mica schist). The breccias start at 174 m depth as polymict breccias with angular clasts of different lithologies and gradually change downward to breccias constituting the dominant lithology, until finally grading into monomict breccia. At the bottom of the borehole, we noted strongly brecciated quartz-feldspar schist. The breccia cement also changes over this interval from gypsum and carbonate cement to fine-grained clastic matrix. Some quartz grains from breccia samples from 192, 194.2, 196.4, 199.3, 201.6, and 204 m depth showed planar deformation features with impact-characteristic orientations. This discovery of unambiguous shock features in drill core samples confirms the impact origin of the Tabun Khara Obo crater. The age of the structure is not yet known. Currently, it is only poorly constrained to post-Cretaceous on stratigraphic grounds.
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Baird, Graham B., Timothy W. Grover, Kevin H. Mahan, Michael G. Frothingham, Markus B. Raschke, Andreas Möller, Adam S. Chumley, Jacob C. Hooker, Nigel M. Kelly, and Julien M. Allaz. "Paleoproterozoic tectonics of the northern Colorado Rocky Mountains Front Range, USA." In Field Excursions in the Front Range and Wet Mountains of Colorado for GSA Connects 2022, 39–66. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.0064(03).

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ABSTRACT Two models have been proposed to explain continental crust generation in accretionary orogens. One model suggests that accretionary orogens are formed by the successive collision of juvenile arcs. The second model invokes tectonic switching, which is the repeated cycles of slab rollback and extensional backarc basin formation followed by basin collapse caused by collision, shallow subduction, and/or increased convergence rate. The northern Colorado Front Range, specifically in and around the Big Thompson, Rist, and Poudre Canyons, offers excellent exposures of Paleoproterozoic rocks to test which accretionary model best explains crust generation for a portion of the Yavapai Province. In this contribution we have two goals: The first is to provide a field-trip guide that augments Mahan et al.’s (2013) field guide, which uses many stops that have become inaccessible or have changed because of catastrophic flooding that occurred in September 2013. This more current guide focuses on a variety of mostly Paleoproterozoic rocks within what some call the Poudre Basin. These rocks include clastic metasedimentary rocks, amphibolite, the Big Thompson Canyon tonalite suite, the northern Front Range granodiorite, granitic pegmatites, and Mesoproterozoic Silver Plume granite. The second goal is to present and synthesize new and existing geochemistry, geochronology, and isotopic data, and then discuss the origins, age, deformation, and metamorphism of these rocks in the context of the proposed tectonic models. These data were synthesized into the following tectonic model for the Poudre Basin. At ca. 1780 Ma, the juvenile Green Mountain arc, located today along the Colorado-Wyoming border, formed and extended shortly thereafter during slab rollback, resulting in the extensional backarc Poudre basin between the diverging arc fragments. Sedimentation within the basin began at inception and continued to ca. 1735 Ma when basin rocks were intruded by the Big Thompson Canyon tonalite suite and the northern Front Range granodiorite, all of which were subsequently metamorphosed and deformed at ca. 1725 Ma. Felsic magmatism and deformation within the basin were perhaps driven by the northward shallow subduction of an oceanic plateau or seamount. This suggests that following accretion of the Green Mountain Arc, tectonic switching explains formation and collapse of the Poudre Basin and creation of some of northern Colorado’s crust.
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Smith Nagihara, S., and J. F. Casey. "Whole-rock geochemistry of amphibolites and metagabbros from the west Iberia Margin, Leg 173." In Proceedings of the Ocean Drilling Program. Ocean Drilling Program, 2001. http://dx.doi.org/10.2973/odp.proc.sr.173.011.2001.

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Conference papers on the topic "Amphibolite geochemistry"

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Baird, Graham, and Adam S. Chumley. "TECTONIC STYLE INSIGHTS FROM PALEOPROTEROZOIC AMPHIBOLITE GEOCHEMISTRY, BIG THOMPSON AND POUDRE CANYONS, NORTHERN COLORADO FRONT RANGE." In GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-380099.

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Vetter, Scott K., Austin Greber, Kaleb Kirk, Zachary Harrison, Allison Scates, Spencer R. Nelson, Rylan Whan, and David Bieler. "MITCHELL DAM AMPHIBOLITES: GEOCHEMISTRY AND PETROLOGY OF CORE HOLE SAMPLES, SENIOR CLASS PROJECT." In 51st Annual GSA South-Central Section Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017sc-289269.

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R, Sierra, David H. Shimabukuro, Jo Black, and Steven Skinner. "GEOCHEMISTRY, GEOCHRONOLOGY, AND THERMOBAROMETRY OF HIGH-PRESSURE AMPHIBOLITES FROM THE CENTRAL ARC AND MELANGE BELT NEAR COLFAX, CALIFORNIA." In Cordilleran Section-117th Annual Meeting-2021. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021cd-363222.

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Hampel, Tim, Michael Rowe, and Adam J. R. Kent. "Reassessing Volatile and Trace Element Mobility at Mount St. Helens (2004-2008) from Amphibole and Melt Inclusion Geochemistry." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.939.

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Geneviève, Tsama Mbani, Ekollo Kingue Ngolle Serge, Tchouffa Bertrand Boris, and Ndong Bidzang François. "GEOCHEMISTRY AND SM-ND DATING OF AMPHIBOLITES OF ESEKA GREEN STONES BELT (NYONG COMPLEX SOUTH CAMEROON): HIGHLIGHTING OF DISTENSIVE EPISODES IN A COMPRESSIVE OROGENIC CONTEXT." In 7th International Scientific Conference GEOBALCANICA 2021. Geobalcanica Society, 2021. http://dx.doi.org/10.18509/gbp210445m.

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Reports on the topic "Amphibolite geochemistry"

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Matte, S., M. Constantin, and R. Stevenson. Mineralogical and geochemical characterisation of the Kipawa syenite complex, Quebec: implications for rare-earth element deposits. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329212.

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The Kipawa rare-earth element (REE) deposit is located in the Parautochton zone of the Grenville Province 55 km south of the boundary with the Superior Province. The deposit is part of the Kipawa syenite complex of peralkaline syenites, gneisses, and amphibolites that are intercalated with calc-silicate rocks and marbles overlain by a peralkaline gneissic granite. The REE deposit is principally composed of eudialyte, mosandrite and britholite, and less abundant minerals such as xenotime, monazite or euxenite. The Kipawa Complex outcrops as a series of thin, folded sheet imbricates located between regional metasediments, suggesting a regional tectonic control. Several hypotheses for the origin of the complex have been suggested: crustal contamination of mantle-derived magmas, crustal melting, fluid alteration, metamorphism, and hydrothermal activity. Our objective is to characterize the mineralogical, geochemical, and isotopic composition of the Kipawa complex in order to improve our understanding of the formation and the post-formation processes, and the age of the complex. The complex has been deformed and metamorphosed with evidence of melting-recrystallization textures among REE and Zr rich magmatic and post magmatic minerals. Major and trace element geochemistry obtained by ICP-MS suggest that syenites, granites and monzonite of the complex have within-plate A2 type anorogenic signatures, and our analyses indicate a strong crustal signature based on TIMS whole rock Nd isotopes. We have analyzed zircon grains by SEM, EPMA, ICP-MS and MC-ICP-MS coupled with laser ablation (Lu-Hf). Initial isotopic results also support a strong crustal signature. Taken together, these results suggest that alkaline magmas of the Kipawa complex/deposit could have formed by partial melting of the mantle followed by strong crustal contamination or by melting of metasomatized continental crust. These processes and origins strongly differ compare to most alkaline complexes in the world. Additional TIMS and LA-MC-ICP-MS analyses are planned to investigate whether all lithologies share the same strong crustal signature.
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Caritat, P. de, and U. Troitzsch. Towards a regolith mineralogy map of the Australian continent: a feasibility study in the Darling-Curnamona-Delamerian region. Geoscience Australia, 2021. http://dx.doi.org/10.11636/record.2021.035.

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Bulk quantitative mineralogy of regolith is a useful indicator of lithological precursor (protolith), degree of weathering, and soil properties affecting various potential landuse decisions. To date, no national-scale maps of regolith mineralogy are available in Australia. Catchment outlet sediments collected over 80% of the continent as part of the National Geochemical Survey of Australia (NGSA) afford a unique opportunity to rapidly and cost-effectively determine regolith mineralogy using the archived sample material. This report releases mineralogical data and metadata obtained as part of a feasibility study in a selected pilot area for such a national regolith mineralogy database and atlas. The area chosen for this study is within the Darling-Curnamona-Delamerian (DCD) region of southeastern Australia. The DCD region was selected as a ‘deep-dive’ data acquisition and analysis by the Exploration for the Future (2020-2024) federal government initiative managed at Geoscience Australia. One hundred NGSA sites from the DCD region were prepared for X-Ray Diffraction (XRD) analysis, which consisted of qualitative mineral identification of the bulk samples (i.e., ‘major’ minerals), qualitative clay mineral identification of the <2 µm grain-size fraction, and quantitative analysis of both ‘major’ and clay minerals of the bulk sample. The identified mineral phases were quartz, plagioclase, K-feldspar, calcite, dolomite, gypsum, halite, hematite, goethite, rutile, zeolite, amphibole, talc, kaolinite, illite (including muscovite and biotite), palygorskite (including interstratified illite-smectite and vermiculite), smectite (including interstratified illite-smectite), vermiculite, and chlorite. Poorly diffracting material (PDM) was also quantified and reported as ‘amorphous’. Mineral identification relied on the EVA® software, whilst quantification was performed using Siroquant®. Resulting mineral abundances are reported with a Chi-squared goodness-of-fit between the actual diffractogram and a modelled diffractogram for each sample, as well as an estimated standard error (esd) measurement of uncertainty for each mineral phase quantified. Sensitivity down to 0.1 wt% (weight percent) was achieved, with any mineral detection below that threshold reported as ‘trace’. Although detailed interpretation of the mineralogical data is outside the remit of the present data release, preliminary observations of mineral abundance patterns suggest a strong link to geology, including proximity to fresh bedrock, weathering during sediment transport, and robust relationships between mineralogy and geochemistry. The mineralogical data generated by this study are presented in Appendix A of this report and are downloadable as a .csv file. Mineral abundance or presence/absence maps are shown in Appendices B and C to document regional mineralogical patterns.
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