Academic literature on the topic 'Sr-Nd-Pb-Hf isotopes'
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Journal articles on the topic "Sr-Nd-Pb-Hf isotopes"
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Tong, Jie, Haibo Zou, Zipei Guo, Liwen Chang, Lizhu Wang, and Yongwei Zhao. "Geochronology and Origin of Quaternary Dacites from the Daliuchong Volcano in the Tengchong Volcanic Field (TVF), SE Tibetan Plateau." Minerals 14, no. 10 (September 30, 2024): 990. http://dx.doi.org/10.3390/min14100990.
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Quaternary volcanoes from the southeastern Tibetan Plateau occur at the Tengchong volcanic field (TVF). The Daliuchong volcano is the largest volcano in the TVF, which has the most felsic compositions with explosive eruptions. The eruption history and origin of the Daliuchong volcano are a matter of debate. In the present paper, we report the groundmass K-Ar ages, whole-rock Sr-Nd-Pb-Hf isotopes, zircon U-Pb ages, and Hf-O isotopic compositions for the Daliuchong volcano to constrain its eruption history and petrogenesis. The groundmass K-Ar ages and zircon U-Pb ages indicate mid-Pleistocene (0.6 Ma to 0.3 Ma) eruptions. The presence of zircon phenocrysts with enriched mantle-like O-Hf isotopes (δ18O < 6‰, and εHf about −2) suggests the involvement of mantle-derived basaltic magmas. The whole-rock Pb isotope compositions and Sr-Nd isotope modeling reveal the involvement of magma from the lower crust. The zircon xenocrysts reveal previously unrecognized 20-Ma magmatic activity at the TVF and contamination of late Cretaceous (66–80 Ma) S-type granites during the formation of the Daliuchong dacites. The dacite magma at Daliuchong was formed by mixing of the mantle-derived magma and lower-crust-derived magma and subsequently contaminated by upper crustal materials, including late Cretaceous S-type granitic rocks.
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Linghu, Miaomiao, Zimu Li, Jinfeng Sun, and Jiheng Zhang. "Magma Source and Petrogenesis of the Early Cretaceous Granites in The Liaodong Peninsula: Evidence from In Situ Apatite Sr-Nd and Zircon Hf-O Isotopes." Minerals 13, no. 4 (April 12, 2023): 545. http://dx.doi.org/10.3390/min13040545.
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Apatite Sr-Nd and zircon Hf-O isotopes are broadly used to trace magma sources and constrain magma evolution processes, further improving our understanding of the origin of granitoids. We present zircon U-Pb ages, whole-rock major and trace elements, and whole-rock Sr-Nd-Hf, zircon Hf-O, and apatite Sr-Nd isotopic data for the coarse-grained quartz monzonite, biotite monzogranite, and granite porphyry in the Yushulinzi pluton in the Liaodong Peninsula, the eastern North China Craton, to establish their magma sources and petrogenesis. The coarse-grained quartz monzonite, biotite monzogranite, and granite porphyry were formed contemporaneously, with zircon U-Pb ages of 123–119 Ma. They share enriched whole-rock Sr-Nd-Hf and zircon Hf isotopic compositions, and the coarse-grained quartz monzonite has crust-like δ18O values (5.7–6.7‰). The coarse-grained quartz monzonite and biotite monzogranite have variable apatite (87Sr/86Sr)i ratios and negative apatite εNd(t) values. These isotopic characteristics indicate that the different rock types in the Yushulinzi pluton were derived from the partial melting of ancient crustal material in the North China Craton. Their geochemical and petrographic characteristics indicate that the crystal-melt segregation model can be employed to elucidate the genetic links among different rock types, with the coarse-grained quartz monzonite representing crystal accumulation and the biotite monzogranite and granite porphyry representing interstitial melts extracted from a crystal-rich magma chamber. Furthermore, the variable apatite Sr isotopic compositions and subtle differences in the peak zircon εHf(t) values of the studied rock samples confirm the possibility of a contribution from shallow crustal components and materials with high εHf(t) values during magma evolution, which is not readily revealed by their whole-rock Sr-Nd-Hf isotopic compositions. These results demonstrate that in situ apatite Sr-Nd and zircon Hf-O isotopic analyses have the potential to provide distinctive insights into the magma sources and evolution of magmatic systems.
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Sakhno, V. G., and L. S. Tsurikova. "Isotopic and geochemical features of the genesis of igneous complexes and ore-magmatic systems in the Chukotka sector of the Russian Arctic coast." LITHOSPHERE (Russia) 20, no. 2 (April 25, 2020): 196–211. http://dx.doi.org/10.24930/1681-9004-2020-20-2-196-211.
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Research subject. The isotopic composition (Pb-Pb, Sm-Nd, Rb-Sr, Os/Os, Hf/Hf, 3 He/4 He, etc.) of magmatic complexes and ore-magmatic systems (OMS) of two ore clusters (Kupolsky and Ilirneysky) located in the subpolar Western Chukotka was studied. These ore clusters differ from each other both in their structural position and the age of their magmatic complexes, within which the largest deposits of Au-Ag type are known. Materials and methods. The Pb-Pb, Rb-Sr, SmNd, Re-Os, Lu-Hf, 3 He/4 He, 40Ar/36Ar and sulphur isotopic systems were studied at the VSEGEI centre for isotopic studies (St. Petersburg), as well as at the Institute of Geology, Geochemistry and Ore Deposits (IGEM, Moscow) and the Laboratory of Stable Isotopes of the Far Eastern Geological Institute (FEGI, Vladivostok). Re and Os were measured using an ELEMENT-2 inductively coupled plasma single-collector mass spectrometer. Sulphur isotopic ratios were measured using a Finnigan MAT 253 isotope mass spectrometer. Results and conclusions. On the basis of the isotope-geochemical data obtained, an assumption was made that various deep sources participated in the magma generation, and the differentiated composition of late melts may reflect the melting processes of the crust upper horizons. When comparing the data on the magmatism of the Ilirneysky and Kupolsky ore clusters, a different degree of crustal rock influence on melt generation was revealed. The Kupolsky ore cluster is characterised by a large influence of mantle sources in intraplate magmatism associated with ore formation processes. This is likely to have determined a greater amount of mineralisation in the Kupolsky cluster compared to the Ilirneysky ore cluster.
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Falloon, Trevor J., Kaj Hoernle, Bruce F. Schaefer, Ilya N. Bindeman, Stanley R. Hart, Dieter Garbe-Schonberg, and Robert A. Duncan. "Petrogenesis of Lava from Christmas Island, Northeast Indian Ocean: Implications for the Nature of Recycled Components in Non-Plume Intraplate Settings." Geosciences 12, no. 3 (March 3, 2022): 118. http://dx.doi.org/10.3390/geosciences12030118.
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Lava samples from the Christmas Island Seamount Province (CHRISP) record an extreme range in enriched mantle (EM) type Sr-Nd-Pb-Hf isotope signatures. Here we report osmium isotope data obtained on four samples from the youngest, Pliocene petit-spot phase (Upper Volcanic Series, UVS; ~4.4 Ma), and four samples from the earlier, Eocene (Lower Volcanic Series, LVS; ~40 Ma) shield building phase of Christmas Island. Osmium concentrations are low (5–82 ppt) with initial Os isotopic values (187Os/188Osi) ranging from (0.1230–0.1679). Along with additional new geochemical data (major and trace elements, Sr-Nd-Pb isotopes, olivine δ18O values), we demonstrate the following: (1) The UVS is consistent with melting of shallow Indian mid-ocean ridge basalt (MORB) mantle enriched with both lower continental crust (LCC) and subcontinental lithospheric mantle (SCLM) components; and (2) The LVS is consistent with recycling of SCLM components related to Gondwana break-up. The SCLM component has FOZO or HIMU like characteristics. One of the LVS samples has less radiogenic Os (γOs –3.4) and provides evidence for the presence of ancient SCLM in the source. The geochemistry of the Christmas Island lava series supports the idea that continental breakup causes shallow recycling of lithospheric and lower crustal components into the ambient MORB mantle.
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Tang, Yu-Wei, Long Chen, Zi-Fu Zhao, and Yong-Fei Zheng. "Geochemical evidence for the production of granitoids through reworking of the juvenile mafic arc crust in the Gangdese orogen, southern Tibet." GSA Bulletin 132, no. 7-8 (November 7, 2019): 1347–64. http://dx.doi.org/10.1130/b35304.1.
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Abstract Although continental crust is characterized by the widespread occurrence of granitoids, the causal relationship between continental crust growth and granitic magmatism still remains enigmatic. While fractional crystallization of basaltic magmas (with or without crustal contamination) and partial melting of mafic lower crust are two feasible mechanisms for the production of granitoids in continental arc regions, the problem has been encountered in discriminating between the two mechanisms by whole-rock geochemistry. This can be resolved by an integrated study of zircon U-Pb ages and Hf-O isotopes together with whole-rock major-trace elements and Sr-Nd-Pb isotopes, which is illustrated for Mesozoic granitoids from the Gangdese orogen in southern Tibet. The results provide geochemical evidence for prompt reworking of the juvenile mafic arc crust in the newly accreted continental margin. The target granitoids exhibit high contents of SiO2 (65.76–70.75 wt%) and Na2O + K2O (6.38–8.15 wt%) but low contents of MgO (0.19–0.98 wt%), Fe2O3 (0.88–3.13 wt%), CaO (2.00–3.82 wt%), Ni (<5.8 ppm), and Cr (≤10 ppm). They are enriched in large ion lithophile elements, Pb, and light rare earth elements but depleted in high field strength elements. The granitoids are relatively depleted in whole-rock Sr-Nd isotope compositions with low (87Sr/86Sr)i ratios of 0.7043–0.7048 and positive εNd(t) values of 0.5–2.6, and have relatively low 207Pb/204Pb and 208Pb/204Pb ratios at given 206Pb/204Pb ratios. Laser ablation–inductively coupled plasma–mass spectrometry and secondary ion mass spectrometry U-Pb dating on synmagmatic zircons yield ages of 77 ± 2–81 ± 1 Ma in the Late Cretaceous for their emplacement. Relict zircons have two groups of U-Pb ages in the late Mesozoic and the late Paleozoic, respectively. The whole-rock Sr-Nd isotopes in the granitoids are quite similar to those of Late Cretaceous mafic rocks in the Gangdese batholith. In addition, both synmagmatic zircons and relict zircons with Late Cretaceous U-Pb ages exhibit almost the same Hf-O isotope compositions to those of the slightly earlier mafic rocks. All these observations indicate that the granitoids were mainly derived from partial melting of the juvenile mafic arc crust. Therefore, reworking of the juvenile mafic arc crust is the mechanism for the origin of isotopically depleted granitoids in southern Tibet. It is this process that leads to differentiation of the juvenile mafic arc crust toward the felsic lithology in the continental arc. In this regard, the granitoids with depleted radiogenic isotope compositions do not necessarily contribute to the crustal growth at convergent plate boundaries.
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CINTRON FRANQUI, NADJA OMARA, SUNG HI CHOI, and DER-CHUEN LEE. "Peridotites and basaltic rocks within an ophiolitic mélange from the SW igneous province of Puerto Rico: relation to the evolution of the Caribbean Plate." Geological Magazine 154, no. 1 (February 2, 2016): 96–118. http://dx.doi.org/10.1017/s001675681500093x.
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AbstractThe geology of Puerto Rico is divided into three regions: the north, central and SW igneous provinces. Characterized by its Jurassic ophiolitic mélange basement, lithology of the SW Igneous Province (SIP) is not related to either of the other two provinces. The ophiolitic mélange is exposed in three peridotite belts: Monte del Estado, Rio Guanajibo and Sierra Bermeja. We present geochemical data to identify the tectonic setting of the SIP peridotite formation and its relation to the evolution of the Caribbean Plate. Comparisons of spinel Cr no. (13–21), Mg no. (63.3–69.6) and TiO2suggest an abyssal peridotite origin; however, only Sierra Bermeja presents high TiO2characteristics of a mid-ocean-ridge-basalt- (MORB-) like melt reaction. Temperatures determined with two-pyroxene geothermometers indicated a cold thermal regime ofc. 800–1050°C, with characteristics of large-offset transform fault abyssal peridotites. The geochemistry and Sr–Nd–Hf–Pb isotopic compositions of basalts within the mélange were also analysed. Las Palmas amphibolites exhibited normal-MORB-like rare earth element (REE) and trace-element patterns, whereas metabasalts and Lower Cajul basalts exhibited island-arc tholeiitic-like patterns. Highly radiogenic Sr isotopes (0.70339–0.70562) of the basalts suggest seawater alteration; however, Pb–Pb and Nd–Hf isotope correlations represent the primary compositions of a Pacific/Atlantic MORB source for the amphibolites, metabasalts and Lower Cajul basalts. We propose that the SIP ophiolitic mélange was formed along a large-offset transform fault, which initiated subduction and preserved both proto-Pacific and proto-Caribbean lithospheric mantle. Younger Upper Cajul basalts exhibited enriched-MORB-like geochemical and isotopic signatures, which can be attributed to a tectonized Caribbean ocean plateau.
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Sun, Xiang, Yongjun Lu, Qiang Li, and Ruyue Li. "A Downgoing Indian Lithosphere Control on Along-Strike Variability of Porphyry Mineralization in the Gangdese Belt of Southern Tibet." Economic Geology 116, no. 1 (November 23, 2020): 29–46. http://dx.doi.org/10.5382/econgeo.4768.
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Abstract The E-trending Gangdese porphyry copper belt in southern Tibet is a classic example of porphyry mineralization in a continental collision zone. New zircon U-Pb geochronological, zircon Hf-O, and bulk-rock Sr-Nd isotope data for the Miocene mineralizing intrusions from the Qulong, Zhunuo, Jiru, Chongjiang, and Lakange porphyry copper deposits and Eocene igneous rocks from the western Gangdese belt, together with literature data, show that both Paleocene-Eocene igneous rocks and Miocene granitoids exhibit coupled along-arc isotopic variations, characterized by bulk-rock ɛNd(t) and zircon ɛHf(t) values increasing from ~84° to ~92°E and then decreasing toward ~95°E. These are interpreted to reflect increasing contributions of subducted Indian continental materials from ~92° to ~84°E and from ~92° to ~95°E, respectively. The Miocene mineralizing intrusions were derived from subduction-modified Tibetan lower crust represented isotopically by the Paleocene-Eocene intrusions, with contributions from Indian plate-released fluids and mafic melts derived from mantle metasomatized by subducted Indian continental materials. Involvement of isotopically ancient Indian continental materials increased from east (Qulong) to west (Zhunuo), which is interpreted to reflect an increasingly shallower angle of the downgoing Indian slab from east to west, consistent with geophysical imaging. Exploration of Gangdese Miocene porphyry copper deposits should focus on the Paleocene-Eocene arc where the subarc mantle was mainly enriched by fluids from the subducted Neo-Tethyan oceanic slab. Neodymium-Hf isotope data for mineralizing igneous rocks from porphyry copper deposits globally show no obvious correlations with Cu endowment. Although Nd-Hf isotopes are useful for imaging lithospheric architecture through time, caution must be taken when using Nd-Hf isotopes to evaluate the potential endowment of porphyry copper deposits, because other factors such as tectonic setting, crustal thickening, magma differentiation, fluid exsolution, and ore-forming processes all play roles in determining Cu endowments and grades.
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Ogasawara, Masatsugu, Mayuko Fukuyama, Rehanul Haq Siddiqui, and Ye Zhao. "Origin of the Ordovician Mansehra granite in the NW Himalaya, Pakistan: constraints from Sr–Nd isotopic data, zircon U–Pb age and Hf isotopes." Geological Society, London, Special Publications 481, no. 1 (October 23, 2018): 277–98. http://dx.doi.org/10.1144/sp481.5.
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AbstractThe Mansehra granite in the NW Himalaya is a typical Lesser Himalayan granite. We present here new whole-rock geochemistry, Rb–Sr and Sm–Nd isotope data, together with zircon U–Pb ages and Hf isotope data, for the Mansehra granite. Geochemical data for the granite show typical S-type characteristics. Zircon U–Pb dating yields 206Pb/238U crystallization ages of 483–476 Ma. The zircon grains contain abundant inherited cores and some of these show a clear detrital origin. The 206Pb/238U ages of the inherited cores in the granite cluster in the ranges 889–664, 1862–1595 and 2029 Ma. An age of 664 Ma is considered to be the maximum age of the sedimentary protoliths. Thus the Late Neoproterozoic to Cambrian sedimentary rocks must be the protolith of the Mansehra granitic magma. The initial Sr isotope ratios are high, ranging from 0.7324 to 0.7444, whereas the εNd(t) values range from −9.2 to −8.6, which strongly suggests a large contribution of old crustal material to the protoliths. The two-stage Nd model ages and zircon Hf model ages are Paleoproterozoic, indicating that the protolith sediments were derived from Paleoproterozoic crustal components.
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Zhong, Yun, Xu Zhang, Zhilei Sun, Jinnan Liu, Wei Li, Yaoliang Ma, Weiliang Liu, Bin Xia, and Yao Guan. "Sr–Nd–Pb–Hf Isotopic Constraints on the Mantle Heterogeneities beneath the South Mid-Atlantic Ridge at 18–21°S." Minerals 10, no. 11 (November 13, 2020): 1010. http://dx.doi.org/10.3390/min10111010.
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In an attempt to investigate the nature and origin of mantle heterogeneities beneath the South Mid-Atlantic Ridge (SMAR), we report new whole-rock Sr, Nd, Pb, and Hf isotopic data from eight basalt samples at four dredge stations along the SMAR between 18°S and 21°S. Sr, Nd, and Pb isotopic data from SMAR mid-ocean ridge basalts (MORBs) at 18–21°S published by other researchers were also utilized in this study. The SMAR MORBs at 18–21°S feature the following ratio ranges: 87Sr/86Sr = 0.70212 to 0.70410, 143Nd/144Nd = 0.512893 to 0.513177, 206Pb/204Pb = 18.05 to 19.50, 207Pb/204Pb = 15.47 to 15.71, 208Pb/204Pb = 37.87 to 38.64, and 176Hf/177Hf = 0.283001 to 0.283175. The 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, and 176Hf/177Hf ratios of these MORBs varied considerably along the SMAR axis. The variable compositions of the Sr–Nd–Pb–Hf isotopes, combined with the corresponding whole-rock major and trace elemental abundances reported in previous studies, suggest that the SMAR MORBs at 18–21°S were probably derived from a heterogeneous mantle substrate related to a mixture of depleted mantle (DM) materials with a small amount (but variable input) of HIMU (high-μ, where μ = 238U/204Pb)- and enriched (EMII)-type materials. The HIMU-type materials likely originated from the proximal St. Helena plume and may have been transported through “pipe-like inclined sublithospheric channels” into the SMAR axial zone. The EMII-type materials possibly originated from a recycled metasomatized oceanic crust that may have been derived from the early dispersion of other plume heads into the subcontinental asthenosphere prior to the opening of the South Atlantic Ocean. In addition, the contributions of subducted sediments, continental crust, and subcontinental lithospheric mantle components to the formation of the SMAR MORBs at 18–21°S may be nonexistent or negligible.
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Chen, Xiao-Dong, Bin Li, Chong-Bo Sun, and Hong-Bing Zhou. "Protracted Storage for Calc-Alkaline Andesitic Magma in Magma Chambers: Perspective from the Nageng Andesite, East Kunlun Orogen, NW China." Minerals 11, no. 2 (February 13, 2021): 198. http://dx.doi.org/10.3390/min11020198.
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Calc-alkaline andesitic rocks are a major product of subduction-related magmatism at convergent margins. Where these melts are originated, how long they are stored in the magma chambers, and how they evolved is still a matter of debate. In this study, we present new data of whole-rock elemental and Sr-Nd-Pb isotope compositions, and zircon U-Pb-Th isotopes and trace element contents of Nageng (basaltic-)andesites in the East Kunlun Orogen (NW China). The similar age and whole-rock elemental and Sr-Nd-Pb isotope contents suggest that the Nageng andesite and basaltic andesite are co-magmatic. Their low initial 87Sr/86Sr (0.7084–0.7086) but negative εNd(t) values (−10.61 to −9.49) are consistent with a magma source from the juvenile mafic lower crust, possibly related to the mantle wedge with recycled sediment input. The U-Pb age gap between the zircon core (ca. 248 Ma) and rim (ca. 240 Ma) reveals a protracted magma storage (~8 Myr) prior to the volcanic eruption. When compared to the zircon rims, the zircon cores have higher Ti content and Zr/Hf and Nb/Ta ratios, but lower Hf content and light/heavy rare earth element ratios, which suggests that the parental magma was hotter and less evolved than the basaltic andesite. The plagioclase accumulation likely resulted in Al2O3-enrichment and Fe-depletion, forming the calc-alkaline signature of the Nageng (basaltic-)andesites. The magma temperature, as indicated by the zircon saturation and Ti-in-zircon thermometry, remained low (725–828 °C), and allowed for the magma chamber to survive over ~8 Myr. The decreasing εHf(t) values from zircon core (avg. 0.21, range: −1.28 to 1.32) to rim (avg. −3.68, range: −7.30 to −1.13), together with the presence of some very old xenocrystic zircons (268–856 Ma), suggest that the magma chamber had undergone extensive crustal contamination.
Dissertations / Theses on the topic "Sr-Nd-Pb-Hf isotopes"
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Labanieh, Shasa. "Géochimie de l'île de la Martinique aux Petites Antilles." Phd thesis, Grenoble 1, 2009. http://www.theses.fr/2009GRE10116.
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L'île de la Martinique a connu l'histoire volcanique la plus complète de l'arc des Petites Antilles, de 25 Ma à l'actuel. L'hétérogénéité chimique et isotopique des laves de l'île est très importante non seulement par rapport aux autres îles de l'arc mais aussi par rapport aux autres arcs intra-océaniques. L'objectif de ces travaux est d'expliquer la variabilité géochimique des laves de la Martinique et de caractériser les processus de genèse des produits volcaniques émis sur l'île. Pour cela, nous avons effectué une étude géochimique approfondie (éléments majeurs, éléments traces, rapports isotopiques du Pb, Sr, Nd et Hf) sur des échantillons de laves représentatifs de toute l'histoire volcanique de la Martinique. Grâce à une collaboration avec Aurélie Germa et Xavier Quidelleur de l'université Orsay - Paris XI, l'étude géochimique a été couplée à une datation des laves par méthode K-Ar. Les laves martiniquaises forment des droites et hyperboles de mélanges entre pôles appauvris mantelliques et pôle enrichis crustaux. Il apparaît que deux mélanges distincts sont visibles, un premier mélange est formé par les laves « anciennes » (entre 25 et 7 Ma) et un deuxième mélange est formé par les laves « récentes » (entre 5 Ma et l'actuel). Les pôles mantelliques et les pôles crustaux impliqués dans les sources des magmas ne sont pas les mêmes avant et après 6 Ma. Ce changement de source est probablement lié au passage de la ride asismique qui a décalé la moitié nord de l'arc des Petites Antilles. L'origine de la signature crustale des laves martiniquaises est testée en comparant un modèle de mélange à la source entre des sédiments de la plaque plongeante et le coin mantellique et un modèle d'assimilation de la croûte de l'arc par les magmas mantelliques ascendants. Le modèle d'assimilation intra-crustale ne peut pas reproduire les tendances décrites par les laves alors que le modèle de mélange à la source le fait parfaitement. La comparaison entre les pôles crustaux impliqués dans les mélanges et les sédiments entrants dans la subduction indique qu'il n'y a pas de fractionnement entre le Pb, le Sr, le Nd et l'Hf ce qui implique que les sédiments sont probablement ajoutés à la source par fusion partielle et non par déshydratation. Le rapport La/Yb des laves martiniquaises apparait comme un proxy de la proportion de sédiments dans la source des magmas et non du taux de fusion partielle ou de la nature de la phase alumineuse du manteau bien que la fusion, de l'ordre de 10%, ait lieu dans la zone de stabilité du grenat. Le gradient géographique du rapport La/Yb au sein de l'île traduit donc un gradient géographique de la proportion de sédiments, et montre que la proportion de sédiments dans la source augmente avec l'éloignement à la fosseMartinique Island has recorded the most complete history of the Lesser Antilles arc, from 25 Ma to present. The chemical and isotopic heterogeneity of the lavas is very large compared to other islands from the same arc and compared to other intra-oceanic arcs. The aim of this study is to explain the chemical and isotopic variability of Martinique lavas and to constrain the processes that took place during the genesis of volcanic products. We did a detailed geochemical study (major elements, minor elements and Pb, Sr, Nd and Hf isotopic ratios) of samples collected all over Martinique Island. Our geochemical study was coupled to precise dating of the same lavas by the K-Ar method through a collaboration with Aurélie Germa and Xavier Quidelleur from the University of Orsay-Paris XI. Martinique lavas define mixing trends between depleted and enriched end-members. Two significantly different trends can be distinguished, one defined by “old” lavas (between 25 and 7 Ma) and one defined by “recent” lavas (between 5 Ma and present). Both depleted and enriched end-members involved in the source of magmas differ before and after 6 Ma. The change of source most probably occurred when the subduction of an aseismic ridge shifted to the West the northern part of the arc. We evaluate the origin of the crustal signature of Martinique lavas through (a) a mixing model between slab sediments and mantle wedge and (b) a crustal assimilation model in which mantle-derived magmas are contaminated by the arc crust. The crustal-contamination model does not reproduce the trends defined by the Martinique lavas whereas the mixing model succeeds. A comparison between crustal end-members as constrained by the mixing trends, and local subducted sediments indicates that there is no decoupling between Pb, Sr, Nd and Hf implying that sediments are added to the mantle wedge through fusion and not dehydration. The La/Yb ratio is a proxy of the proportion of sediments involved in the genesis of the lavas. It is not governed by the melting degree or the nature of the residual aluminous phase in the mantle, even though lavas are generated by approximately 10% partial melting of a garnet-bearing mantle source. We show that La/Yb defines a spatial gradient in the island, suggesting a geographical gradient of the proportion of sediments
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Labanieh, Shasa. "Géochimie de l'île de la Martinique aux Petites Antilles." Phd thesis, Université Joseph Fourier (Grenoble), 2009. http://tel.archives-ouvertes.fr/tel-00467762.
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L'île de la Martinique a connu l'histoire volcanique la plus complète de l'arc des Petites Antilles, de 25 Ma à l'actuel. L'hétérogénéité chimique et isotopique des laves de l'île est très importante non seulement par rapport aux autres îles de l'arc mais aussi par rapport aux autres arcs intra-océaniques. L'objectif de ces travaux est d'expliquer la variabilité géochimique des laves de la Martinique et de caractériser les processus de genèse des produits volcaniques émis sur l'île. Pour cela, nous avons effectué une étude géochimique approfondie (éléments majeurs, éléments traces, rapports isotopiques du Pb, Sr, Nd et Hf) sur des échantillons de laves représentatifs de toute l'histoire volcanique de la Martinique. Grâce à une collaboration avec Aurélie Germa et Xavier Quidelleur de l'université Orsay - Paris XI, l'étude géochimique a été couplée à une datation des laves par méthode K-Ar. Les laves martiniquaises forment des droites et hyperboles de mélanges entre pôles appauvris mantelliques et pôle enrichis crustaux. Il apparaît que deux mélanges distincts sont visibles, un premier mélange est formé par les laves « anciennes » (entre 25 et 7 Ma) et un deuxième mélange est formé par les laves « récentes » (entre 5 Ma et l'actuel). Les pôles mantelliques et les pôles crustaux impliqués dans les sources des magmas ne sont pas les mêmes avant et après 6 Ma. Ce changement de source est probablement lié au passage de la ride asismique qui a décalé la moitié nord de l'arc des Petites Antilles. L'origine de la signature crustale des laves martiniquaises est testée en comparant un modèle de mélange à la source entre des sédiments de la plaque plongeante et le coin mantellique et un modèle d'assimilation de la croûte de l'arc par les magmas mantelliques ascendants. Le modèle d'assimilation intra-crustale ne peut pas reproduire les tendances décrites par les laves alors que le modèle de mélange à la source le fait parfaitement. La comparaison entre les pôles crustaux impliqués dans les mélanges et les sédiments entrants dans la subduction indique qu'il n'y a pas de fractionnement entre le Pb, le Sr, le Nd et l'Hf ce qui implique que les sédiments sont probablement ajoutés à la source par fusion partielle et non par déshydratation. Le rapport La/Yb des laves martiniquaises apparait comme un proxy de la proportion de sédiments dans la source des magmas et non du taux de fusion partielle ou de la nature de la phase alumineuse du manteau bien que la fusion, de l'ordre de 10%, ait lieu dans la zone de stabilité du grenat. Le gradient géographique du rapport La/Yb au sein de l'île traduit donc un gradient géographique de la proportion de sédiments, et montre que la proportion de sédiments dans la source augmente avec l'éloignement à la fosse.
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王冰媚 and Ping-mei Jean Wong. "Geochemistry, U-Pb and Sr-Nd-Hf isotopes of the Baijuhuajian A-type granites in Zhejiang Province: evidence for acontinuous extensional regime in the mid and late mesozoic." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557297.
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Smietana, Magali. "Pétrologie, géochronologie (K-Ar) et géochimie élémentaire et isotopique (Sr, Nd, Hf, Pb) de laves anciennes de la Réunion : Implications sur la construction de l’édifice volcanique." Thesis, La Réunion, 2011. http://www.theses.fr/2011LARE0012/document.
Full textAbstract:
Le système volcanique de La Réunion est formé de la coalescence des massifs du Piton des Neiges et du Piton de la Fournaise. Son édification, liée à l’activité d’un panache mantellique, est caractérisée par une phase de croissance sous-marine, puis subaérienne, suivie d’une période de dégénérescence, comme proposé classiquement pour les volcans boucliers océaniques d’Hawaii. De précédentes études ont montré que l’activité subaérienne de La Réunion aurait débuté il y a environ 2,2 Ma. Les analyses géochimiques menées jusqu’alors sur les produits associés à cette activité volcanique (subaérienne et sous-marine) ont montré un caractère chimique transitionnel avec une composition isotopique (87Sr/86Sr, 143Nd/144Nd et 176Hf/177Hf) particulièrement homogène pour un volcanisme de point chaud. Dans cette étude, nous montrons que des laves sous-marines récemment identifiées sous la série basique du Piton de la Fournaise (au sein de la sur Rift Zone Nord-Est) ainsi que des laves subaériennes affleurant à la base de canyons incisés dans le massif (Série Différenciée de la Rivière des Remparts), présentent des caractéristiques ne s’inscrivant pas dans le modèle d’évolution proposé précédemment pour ce volcan. Se pose donc la question de la nature et de l’origine de ces laves, ainsi que de leur place et appartenance dans l’édification du système volcanique réunionnais. De nouvelles investigations pétro-géochimiques et géochronologiques ont été menées sur la partie sous-marine de l’édifice de La Réunion. Elles révèlent l’existence d’un groupe de laves exceptionnel. Leur composition se distingue clairement de celle des échantillons communément analysés à La Réunion et montre (1) un enrichissement en éléments incompatibles couplé isotopiquement à (2) un rapprochement vers un pôle mantellique enrichi de type EM. Ces particularités géochimiques démontrent que le panache mantellique possède (1) une source hétérogène affectée par (2) des taux de fusion variables. De plus, deux échantillons de ce nouveau groupe datés à 3,77 (0,08) et à 3,34 (0,07) Ma étendent considérablement la période d’activité connue de l’édifice. Ces âges remarquables font de ces laves les plus anciennes jamais datées à La Réunion. La nature géochimique ainsi que la position stratigraphique des laves de cette étude (échantillons subaériens et sous-marins des massifs du Piton des Neiges et du Piton de la Fournaise) impliquent une réinterprétation du schéma d’évolution global de l’île. Contrairement aux études précédentes, nos résultats sur ces laves montrent que : (1) Les laves différenciées de la Rivière des Remparts, qui sont des laves subaériennes, de part leur position stratigraphique et géographique sous-jacente au Piton de la Fournaise et par analogie avec le Piton des Neiges, ne peuvent être reliées à l’activité de la Fournaise, (2) Le signal isotopique du groupe de laves sous-marines de la Rift Zone Nord-Est de la Fournaise, révèlent l’hétérogénéité de la source du panache mantellique sous La Réunion, source que nous identifions comme des enclaves d’éclogite contenues dans une lherzolite à spinelle, (3) L’âge plus ancien de ces laves sous-marines et leur localisation sous le flanc Est de la Fournaise remet en questions le schéma jusqu’alors admis pour l’édification de l’île de La Réunion reposant sur la construction du Piton des Neiges puis celle, adjacente, du Piton de la Fournaise. En conséquence, nos données géochimiques et géochronologiques sont de nouveaux arguments en faveur de l’élaboration d’un modèle d’évolution plus complexe, suggérant l’existence d’un troisième massif volcanique. Il est en accord avec les précédents travaux de pétrologie et de géophysique suggérant l’existence d’un troisième édifice à l’Est de La Réunion, communément appelé le Volcan des AlizésThe volcanic system of La Reunion is made of the coalescent Piton des Neiges and Piton de la Fournaise edifices. Its formation, associated with the activity of a mantle plume, is characterized by phases of submarine and subaerial growth, followed by a period of destruction, as described in the classical model proposed for Hawaiian Island volcanoes. Previous studies showed that the subaerial activity of La Reunion would have started around 2.2 Ma ago. Geochemical analyses carried out on the products associated with subaerial and submarine volcanism revealed their transitional chemical nature and their peculiar homogeneous isotopic compositions (87Sr/86Sr, 143Nd/144Nd et 176Hf/177Hf) for a hotspot derived magmatism. In this study, we show that some unusual submarine lavas were recently identified below the basal series of Piton de la Fournaise volcano (dredged on the North-East Rift Zone of la Fournaise) and below the subaerial lavas outcropping at the base of the differentiated series of Rivière des Remparts, indicate that the evolution of La Reunion system is probably more complex than previously suggested. The question of the nature and origin of these lavas, together with their implication on the formation of La Reunion, is an issue of major interest in order to better constrain the global evolution of the volcanic system. As a consequence, new petrological, geochemical and geochronological investigations were conducted on the submarine part of La Reunion edifice. They revealed the existence of a geochemically exceptional group of lavas. Its composition is clearly different from common samples of La Reunion and presents (1) an enrichment in incompatible elements and (2) tends toward an enriched EM endmember. These chemical specificities reveal that the source of La Reunion magmatic products is (1) an heterogeneous source affected by (2) variable melting degrees. Moreover, two samples of this new group dated at 3.77 (0,08) and 3.34 (0,07) Ma extend considerably the period of activity of the island. These rocks are the oldest samples ever dated at La Reunion. The nature and stratigraphical location of subaerial and submarine samples from Piton des Neiges and Piton de la Fournaise imply a new interpretation of the global evolution of the island. Unlike previous studies, our results indicate that :(1) The differentiated subaerial lavas from Rivière des Remparts, due to their stratigraphical and geographical location underlying Piton de la Fournaise, and by analogy with the Piton des Neiges, cannot be linked to the activity of Piton de la Fournaise. (2) The isotope signature of the submarine lava group from the North-East Rift Zone of Piton de la Fournaise, reveals the heterogeneous character of the mantle source under La Reunion Island, that can be modelled as embedded eclogite in a matrix of spinel lherzolite, (3) The age of this submarine group and its location under the eastern flank of Piton de la Fournaise, imply a more complex model of evolution of La Reunion. Therefore, our geochemical and geochronological data are new arguments suggesting the existence of a third volcanic center on the island. This assumption confirms the previous petrological and geophysical evidence supporting the existence of this volcano at the East of La Reunion, commonly called Les Alizés volcano
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Wong, Ping-mei Jean. "Geochemistry, U-Pb and Sr-Nd-Hf isotopes of the Baijuhuajian A-type granites in Zhejiang Province evidence for a continuous extensional regime in the mid and late mesozoic /." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557297.
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Smietana, Magali. "Pétrologie, géochronologie (K-Ar) et géochimie élémentaire et isotopique (Sr, Nd, Hf, Pb) de laves anciennes de la Réunion : Implications sur la construction de l'édifice volcanique." Phd thesis, Université de la Réunion, 2011. http://tel.archives-ouvertes.fr/tel-00716829.
Full textAbstract:
Le système volcanique de La Réunion est formé de la coalescence des massifs du Piton des Neiges et du Piton de la Fournaise. Son édification, liée à l'activité d'un panache mantellique, est caractérisée par une phase de croissance sous-marine, puis subaérienne, suivie d'une période de dégénérescence, comme proposé classiquement pour les volcans boucliers océaniques d'Hawaii. De précédentes études ont montré que l'activité subaérienne de La Réunion aurait débuté il y a environ 2,2 Ma. Les analyses géochimiques menées jusqu'alors sur les produits associés à cette activité volcanique (subaérienne et sous-marine) ont montré un caractère chimique transitionnel avec une composition isotopique (87Sr/86Sr, 143Nd/144Nd et 176Hf/177Hf) particulièrement homogène pour un volcanisme de point chaud. Dans cette étude, nous montrons que des laves sous-marines récemment identifiées sous la série basique du Piton de la Fournaise (au sein de la sur Rift Zone Nord-Est) ainsi que des laves subaériennes affleurant à la base de canyons incisés dans le massif (Série Différenciée de la Rivière des Remparts), présentent des caractéristiques ne s'inscrivant pas dans le modèle d'évolution proposé précédemment pour ce volcan. Se pose donc la question de la nature et de l'origine de ces laves, ainsi que de leur place et appartenance dans l'édification du système volcanique réunionnais. De nouvelles investigations pétro-géochimiques et géochronologiques ont été menées sur la partie sous-marine de l'édifice de La Réunion. Elles révèlent l'existence d'un groupe de laves exceptionnel. Leur composition se distingue clairement de celle des échantillons communément analysés à La Réunion et montre (1) un enrichissement en éléments incompatibles couplé isotopiquement à (2) un rapprochement vers un pôle mantellique enrichi de type EM. Ces particularités géochimiques démontrent que le panache mantellique possède (1) une source hétérogène affectée par (2) des taux de fusion variables. De plus, deux échantillons de ce nouveau groupe datés à 3,77 (0,08) et à 3,34 (0,07) Ma étendent considérablement la période d'activité connue de l'édifice. Ces âges remarquables font de ces laves les plus anciennes jamais datées à La Réunion. La nature géochimique ainsi que la position stratigraphique des laves de cette étude (échantillons subaériens et sous-marins des massifs du Piton des Neiges et du Piton de la Fournaise) impliquent une réinterprétation du schéma d'évolution global de l'île. Contrairement aux études précédentes, nos résultats sur ces laves montrent que : (1) Les laves différenciées de la Rivière des Remparts, qui sont des laves subaériennes, de part leur position stratigraphique et géographique sous-jacente au Piton de la Fournaise et par analogie avec le Piton des Neiges, ne peuvent être reliées à l'activité de la Fournaise, (2) Le signal isotopique du groupe de laves sous-marines de la Rift Zone Nord-Est de la Fournaise, révèlent l'hétérogénéité de la source du panache mantellique sous La Réunion, source que nous identifions comme des enclaves d'éclogite contenues dans une lherzolite à spinelle, (3) L'âge plus ancien de ces laves sous-marines et leur localisation sous le flanc Est de la Fournaise remet en questions le schéma jusqu'alors admis pour l'édification de l'île de La Réunion reposant sur la construction du Piton des Neiges puis celle, adjacente, du Piton de la Fournaise. En conséquence, nos données géochimiques et géochronologiques sont de nouveaux arguments en faveur de l'élaboration d'un modèle d'évolution plus complexe, suggérant l'existence d'un troisième massif volcanique. Il est en accord avec les précédents travaux de pétrologie et de géophysique suggérant l'existence d'un troisième édifice à l'Est de La Réunion, communément appelé le Volcan des Alizés.
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Höfig, Tobias Walter [Verfasser]. "Geochemical (major and trace elements and Sr-Nd-Hf-Pb isotopes) characterization of the upper oceanic crust (sediments to gabbros) at ODP/IODP Site 1256 in the eastern Central Pacific / Tobias Walter Höfig." Kiel : Universitätsbibliothek Kiel, 2017. http://d-nb.info/1138979562/34.
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Höfig, Tobias [Verfasser]. "Geochemical (major and trace elements and Sr-Nd-Hf-Pb isotopes) characterization of the upper oceanic crust (sediments to gabbros) at ODP/IODP Site 1256 in the eastern Central Pacific / Tobias Walter Höfig." Kiel : Universitätsbibliothek Kiel, 2017. http://nbn-resolving.de/urn:nbn:de:gbv:8-diss-153979.
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Janin, Myriam. "Le plateau Amsterdam-St. Paul : caractérisation du point chaud éponyme et évolution de son interaction avec la dorsale Sud-est Indienne." Brest, 2010. https://tel.archives-ouvertes.fr/tel-00592036.
Full textAbstract:
Le plateau Amsterdam-St. Paul (ASP) est issu de l’interaction entre le point chaud éponyme et la dorsale sud-est Indienne. Il est prolongé au nord-est par la chaîne des Poètes Disparus, une chaîne volcanique liée à l’activité intraplaque du point chaud, Leur étude révèle que la composition du point chaud nécessite la présence dans le manteau source de croûte océanique chargée de sédiments pélagiques recyclée via subduction il y a 1,5Ga. Le panache ASP s’exprime en surface de manière discontinue et à la faveur de zone de faiblesses. La construction de la chaîne est ainsi directement liée (1) aux pulses du panache et (2) à la déformation diffuse liée au mouvement des plaques Capricorne et Australie. Des datations K-Ar révèlent que cette chaîne de volcans est constituée de: (1) une ancienne génération datée à ~9Ma et constituée d’édifices imposants, ayant probablement eu une phase émergée et (2) une jeune génération, âgée de moins de 2Ma, et constituée d’édifices plus petits, formés suite à la migration de matériel issu du panache sous le plateau ASP. Le panache présente en outre un mouvement propre de l’ordre de 1-2 cm/an vers le sud-ouest. Les compositions élémentaires et isotopiques (Sr-Nd-Pb-Hf) des laves émises sur le plateau ASP sont très variables et révèlent que manteau sous-jacent est hétérogène. Il consiste en un manteau appauvri contaminé par des lambeaux de croûte continentale inférieure, composés de granulites à grenat et plagioclase, probablement délaminée pendant la fracturation du Gondwana. Les résultats de cette étude affermissent donc le modèle proposé de recyclage dans le manteau supérieur de granulites comme origine de l’anomalie DUPALThe Amsterdam-St Paul plateau (ASP) is an oceanic plateau built from the interaction between ASP hotspot and the Southeast Indian ridge. P volcanic chain, called the chain of the dead Poets (CDP), lies to its northward and related to the hotspot intraplate activity. Their study reveals that ASP plume composition comes from oceanic crust and pelagic sediments recycled in the mantle through a 1,5Ga subduction process, ASP plume activity is pulsatile and occurs preferentially on weakness zones. The CDP construction results thus from (1) the plume pulses and (2) the diffuse divergent boundary between the Capricorn and Australian plates. K-Ar datings reveal that this volcanic chain is made of two generations of seamounts: (1) an old one, of about 9Ma and made of large edifices which had probably a sub-aerial period and (2) a young one, younger than 2Ma, and made of small edifices related to some pounded plume pulse material. In addition, ASP plume has an own motion of about 1-2 cm/yr to the south-west. The ASP plateau lavas compositions (major and trace elements and Sr-Nd-Pb-Hf isotopes) show en important variability and reveal that the underlying mantle is heterogeneous. It is made of a depleted mantle with lower continental crust strips in the form of garnet-plagioclase granulites, probably delaminated during the Gondwana breakup. The lower continental crust s one of the hypotheses for DUPAL anomaly origin and our data support this assumption
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Alizadeh, Noudeh Shiva. "Evolution pétrologique des séries volcaniques du massif de Talysh (Iran du NW) à la transition Caucase-Caspienne et implications géodynamiques." Electronic Thesis or Diss., Chambéry, 2024. http://www.theses.fr/2024CHAMA053.
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Le magmatisme cénozoïque de la ceinture orogénique qui relie les zones tectoniques de l'Iran, du bloc arménien méridional (petit Caucase) et de la Turquie, reste un sujet de débat. Cette recherche se concentre sur l'épaisse succession géologique de roches volcaniques shoshonitiques calco-alcalines riches en K exposées dans le massif de Talysh, qui fait partie de la ceinture magmatique de l'Alborz, dans le nord-ouest de l'Iran. L'objectif de cette étude est d'étudier les roches volcaniques relativement peu étudiées du massif de Talysh afin de mieux contraindre le cadre géodynamique du magmatisme pendant la convergence régionale. Une étude complète incluant de nouvelles données de terrain, la chimie minérale, la géochimie des éléments majeurs et traces des roches totales, la composition isotopique (Sr, Nd, Pb, Hf), la géochronologie 40Ar-39Ar, et le zircon U-Pb. Cette montre une série magmatique de basaltes riches en olivine, basaltes à clinopyroxène-phyrique, basaltes à clinopyroxène-phyrique, basaltes à amphibole-phyrique, téphrites, trachy-andésites et roches pyroclastiques. Ils contiennent de multiples populations de cristaux : olivine, clinopyroxène, amphibole et phlogopite, avec des textures de rééquilibrage ainsi qu'une zonation oscillatoire et inverse complexe, des textures criblées et des textures de résorption, ce qui suggère que les magmas ont été stockés dans et différenciés dans des chambres magmatiques avec des réinjections successives avant l'éruption. En outre, les âges 40Ar-39Ar de la biotite et des amphiboles des basaltes et les âges U-Pb du zircon des roches pyroclastiques indiquent que l'activité volcanique s'est déroulée pendant ~ 10 Myr (49-38 Myr). L'enrichissement en LILE et l'appauvrissement en Nb, Ta et Ti sont des caractéristiques des laves de Talysh, qui présentent des caractéristiques géochimiques d'arc. Leurs compositions isotopiques varient : 87Sr/86Sr (i) de 0,7045 à 0,7066, ɛNd(i) de ~-2,2 à +1,7, et ɛHf(i) de -2,5 à +3,6. Les roches ont des compositions radiogéniques en plomb (206Pb/204Pb de 18,51 à 19,04, 207Pb/204Pb de 15,59 à 15,63, et 208Pb/204Pb de 38,67 à 39,15). Les éléments majeurs de la plupart des échantillons primitifs (MgO > 5 % en poids) sont comparables à ceux des fusions partielles à faible degré (4-9%) d'une lherzolite à grenat et spinelle avec des rapports grenat:spinelle de 40:60 à 20:80. Les résultats obtenus par géothermobarométrie clinopyroxène-liquide indiquent une variété de réservoirs magmatiques, allant de niveaux profonds (79-60 km) à des niveaux moins profonds (2 km). Les rapports isotopiques de Sr, Nd, Pb et Hf, ainsi que les profils similaires d'éléments traces incompatibles normalisés par la chondrite et par le manteau primitif, ainsi que les estimations thermobarométriques sur les cristaux d'olivine, de clinopyroxène et d'amphibole, suggèrent que la source mantellique est une source asthénosphérique enrichie et que de la croûte continentale a été mélangée au cours du processus de différenciation. Les données sont cohérentes avec la fusion partielle d'un manteau sous-continental à grenat modifié par subduction et les interactions avec un manteau à spinelle pendant l'ascension magmatique. La phase magmatique éocène pourrait avoir été déclenchée par une remontée de l'Asthénosphère liée au début de la subduction à pendage sud du bassin transcaucasien. L'ascension magmatique a probablement été facilitée par des failles décrochantes trans-lithosphériques mises en évidence par les données paléomagnétiques. Le passage d'une composante magmatique calco-alcaline à une composante magmatique plus alcaline avec le temps, du sud au nord du massif de Talysh, suggère un raidissement de la plaque en réponse à un retournement à l'Éocène supérieur. Après cette période, le volcanisme s'est arrêté dans le Talysh Sud et a considérablement diminué dans le massif du Talysh Nord, où il a évolué vers un magmatisme de type adakitique au cours du Miocène supérieur et du QuaternaireThe Cenozoic magmatism of the Central Tethyan orogenic belt, which links the tectonic zones of Iran, the South Armenian Block (lesser Caucasus), and Turkey, remains a topic of debate. This research focuses on the thick geological succession of high-K calc-alkaline shoshonitic volcanic rocks exposed in the Talysh Massif, part of the Alborz magmatic belt, northwestern Iran. The aim of this study is to investigate the relatively unstudied volcanic rocks of the Talysh Massif to better constrain the geodynamic setting of magmatism during regional convergence. A comprehensive study including new field data, mineral chemistry, bulk-rock major and trace element geochemistry, isotope composition (Sr, Nd, Pb, Hf), geochronology 40Ar-39Ar, and zircon U-Pb. We classify them as olivine, clinopyroxene-phyric basalts, clinopyroxene-phyric basalts, amphibole-phyric basalts, tephrites, trachy-andesites, and pyroclastic rocks. They contain multiple crystal populations, including phenocrysts, antecrysts, and xenocrysts: olivine, clinopyroxene, amphibole, and re-equilibrium phlogopite, along with complex oscillatory and reverse zoning, sieve textures, and resorption textures, which suggests that the magmas stalled and differentiated in the crust prior to eruption. Olivine-clinopyroxene-phyric samples in the southern part of the study area exhibit olivine phenocrysts chemically balanced with their host rock, with a slight zoning from high-Mg# cores (Mg# = 90) to rims (Mg# = 80). Furthermore, the amphiboles, biotite 40Ar-39Ar ages of basalts, and zircon U-Pb ages of pyroclastic rocks indicate that volcanic activity took place for ~ 10 Myr (between 49 and 38 Myr). Enrichment in LILE and depletion in Nb, Ta, and Ti are characteristics of the Talysh lavas, which exhibit arc geochemical features. They have isotopic compositions that vary, for 87Sr/86Sr (i) from 0.7045 to 0.7066, for ɛNd(i) from ~-2.2 to +1.7, and ɛHf(i) from -2.5 to +3.6. The rocks have radiogenic lead 206Pb/204Pb ratios from 18.51 to 19.04, 207Pb/204Pb from 15.59 to 15.63, and 208Pb/204Pb from 38.67 to 39.15. The major elements of most primitive samples (MgO > 5 wt%) are comparable to those of melts obtained from low-degree (4–9%) partial melting of a spinel-garnet lherzolite with garnet:spinel ratios of 40:60 to 20:80. The results obtained from clinopyroxene-liquid geothermobarometry indicate a variety of magma reservoirs, ranging from deep levels (79–60 km) to shallower levels (2 km). The isotopic ratios of Sr, Nd, Pb, and Hf, as well as the similar chondrite-normalized REE and primitive-mantle-normalized incompatible trace element patterns along thermobarometry estimates on olivine, clinopyroxene, and amphibole crystals, suggests that the mantle source is an enriched asthenospheric source, and that continental crust was mixed in during the differentiation process. The data are consistent with the partial melting of a garnet-bearing subduction-modified subcontinental mantle and interactions with a spinel-bearing mantle during magmatic ascent. This magmatic flare-up could have been triggered by an asthenosphere upwelling related to the onset of south-dipping subduction of the Transcaucasus basin. Asthenosphere flow and magmatic ascent were likely facilitated by trans-lithospheric strike-slip faults and block rotations highlighted by paleomagnetic data. A transition from calc-alkaline towards a more alkaline magmatic component with time, from south to north of the Talysh massif, suggests a slab steepening in response to roll-back in the Late Eocene. After this period, volcanism stopped in the South Talysh and significantly decreased in the North Talysh massif, where it evolved into an adakitic-type magmatism during the Late Miocene and Quaternary
Book chapters on the topic "Sr-Nd-Pb-Hf isotopes"
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Gottlieb, Eric S., Elizabeth L. Miller, John W. Valley, Christopher M. Fisher, Jeffrey D. Vervoort, and Kouki Kitajima. "Zircon petrochronology of Cretaceous Cordilleran interior granites of the Snake Range and Kern Mountains, Nevada, USA." In Tectonic Evolution of the Sevier-Laramide Hinterland, Thrust Belt, and Foreland, and Postorogenic Slab Rollback (180–20 Ma). Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2555(02).
Full textAbstract:
ABSTRACT We addressed fundamental questions about the lithology, age, structure, and thermal evolution of the deep crust of the retroarc hinterland of the North American Cordilleran orogen through systematic investigation of zircons from Cretaceous plutons in the Snake Range and Kern Mountains of east-central Nevada. Geochronological (U-Pb) and geochemical (trace element, O and Hf isotopes) characterization of pre- and synmagmatic growth domains of zircons, coupled with traditional petrologic methods (petrography, field relationships, and whole-rock major-element, trace-element, and Sr-Nd and Pb isotope geochemistry), fingerprinted temporal variations in crustal contributions to magmatism. The samples are typical felsic, peraluminous Cordilleran interior granitoids that formed between 102 ± 2 Ma and 71 ± 1 Ma (95% confidence). Over the entire time span of magmatism, 87Sr/86Srinitial, εNd(t), 208Pb/204Pb, and εHf(t) exhibit incrementally more “crustal” ratios. The oldest and youngest samples, respectively, predate and postdate all published timing constraints of Cretaceous peak metamorphism in the region and exhibit the least and most radiogenic whole-rock isotopic results in the study (87Sr/86Srinitial = 0.7071 vs. 0.7222; εNd(t) = −3.4 vs. −18.8; 208Pb/204Pb = 38.8 vs. 40.1). Accordingly, the least intrasample variability of εHf(t), δ18OZrc, and trace-element ratios in magmatic zircon domains is also observed in these oldest and youngest samples, whereas greater intrasample variability is observed in intermediate-age samples that intruded during peak metamorphism. The geochemistry of zircon growth in the intermediate-age samples suggests assimilation of partially molten metasedimentary crust led to increased heterogeneity in their magma chemistry. Interaction of magmas with distinctive crust types is indicated by contrasts between four categories of inherited zircon observed in the studied intrusions: (1) detrital zircon with typical magmatic trace-element ratios; (2) zircon derived from high-grade 1.8–1.6 Ga basement; (3) zircon with anomalously low δ18O of uncertain origin, derived from 1.7/2.45 Ga basement (or detritus derived thereof); and (4) zircon from variably evolved Jurassic–Early Cretaceous deep-seated intrusions. The progression of zircon inheritance patterns, correlated with evolving geochemical signatures, in Late Cretaceous granitic plutons is best explained by early, relatively primitive intrusions and their penecontemporaneously metamorphosed country rock having been tectonically transported cratonward and superposed on older basement, from which the later, more-evolved Tungstonia pluton was generated. This juxtaposition consequentially implies tectonic transport of synorogenic plutonic rocks occurred in the Cordilleran hinterland during the Sevier orogeny as a result of the interplay of retroarc magmatism and convergent margin tectonism.
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Konopelko, Dmitry L. "Chapter 1. Current state of research problem." In PALEOZOIC GRANITOID MAGMATISM OF WESTERN TIEN SHAN, 14–34. St. Petersburg State University, 2020. http://dx.doi.org/10.21638/11701/9785288060250.02.
Full textAbstract:
Chapter 1 provides a review of current understanding of geological structure and history of western Tien Shan and spatial distribution and characteristic features of the Paleozoic granitoid series. Because the main volume of granitoid series of western Tien Shan is represented by postcollisional magmatic series, models for postcollisional magmatism are specifically described in the second part of this Chapter. Finally, principles of isotope mapping and interpretation of genesis of granitoid series utilizing Nd-Sr-Pb-Hf isotopic data, which were applied in this work, are described in the last section of this Chapter.
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Konopelko, Dmitry L. "Chapter 3. Postcollisional intrusions of the Alai Segment of South Tien Shan." In PALEOZOIC GRANITOID MAGMATISM OF WESTERN TIEN SHAN, 70–101. St. Petersburg State University, 2020. http://dx.doi.org/10.21638/11701/9785288060250.04.
Full textAbstract:
The early Permian intrusions of the Alai Segment of the South Tien Shan comprise four geochemically contrasting intrusive series, including (1) I-type and (2) shoshonitic granitoids, (3) peraluminous granitoids including S-type leucogranites and (4) alkaline rocks and carbonatites, closely associated in space and time. New geochronological data indicate that diverse magmatic series of the Alai segment formed virtually coevally in a post-collisional setting. Five U-Pb zircon rock ages in the range 287 – 281 Ma, in combination with published ages, define the main post-collisional magmatic pulse at 290 - 280, which is similar to ages of post-collisional intrusions elsewhere in the South Tien Shan. The Sr-Nd-Pb-Hf isotopic compositions of the studied intrusions are consistent with the reworking of crustal material with 1.6 – 1.1 Ga average crustal residence times indicating the formation of the Alai segment of the South Tien Shan on a continental basement with Mesoproterozoic or older crust. It is suggested that position of the Alai microcontinent between two major sutures enabled delamination of its lithospheric mantle, which triggered the diverse post-collisional magmatism as a result of interaction of ascending asthenospheric material with lithospheric mantle and various crustal protoliths.
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Straub, S. M., A. Gomez-Tuena, and M. J. Dorais. "Data report: major and trace element and Sr-Nd-Pb-Hf isotope composition of three granite clasts from Hole U1501D in the South China Sea (IODP Expedition 367/368/368X)." In Volume 367/368: South China Sea Rifted Margin. International Ocean Discovery Program, 2022. http://dx.doi.org/10.14379/iodp.proc.367368.202.2022.
Full textConference papers on the topic "Sr-Nd-Pb-Hf isotopes"
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Wang, Feng, Kai-Chen Xing, Wen-Liang Xu, and Fang-Zhen Teng. "Sr-Nd-Pb-Hf-Mg Isotopes Tracing Fossil Ridge Subduction: A Case Study in the Easternmost Central Asian Orogenic Belt." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2719.
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Pourmand, Ali, Larry Peterson, Arash Sharifi, Hayley Flanagan, Anne Barkley, Cassandra Gaston, Emily Mellicant, and Keiran Swart. "Chasing dust across glacial-interglacial North Africa through radiogenic Sr-Nd-Hf-Pb isotopes of eolian deposits off the coast of West Africa." In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.11224.
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Fan, Peng, Bin Zhou, Aihua Xi, Kui Han, Xinxing Qiao, and Liang Pan. "Neo-Tethyan subduction slab-rollback in the southern Lhasa terrane, Tibet: Perspective from zircon U–Pb geochronology, geochemistry and Sr-Nd-Hf isotopes." In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.8835.
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Fukuyama, Mayuko, Masatsugu Ogasawara, Mami Takehara, and Kenji Horie. "The formation of skarn deposit of the Kamaishi Mine in the Kitakami Mountains, Japan: constraints from Sr-Nd isotopic data, zircon U-Pb age and Hf isotopes." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.6925.
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Wang, Jingyu, Xiaoping Long, Chutian Shu, and Caiyun Lan. "Early Paleoproterozoic Oceanic Subduction in the Southern Margin of North China Craton: Constraints from Zircon U–Pb Geochronology, Geochemistry and Sr-Nd-Hf Isotopes of ca. 2.3 Ga Mafic Intrusions." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2732.
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Messa, Cole, Kenneth Sims, Mark Stelten, Brandi L. Lawler, and Mel A. Kuntz. "DECOUPLED ASSIMILATION-FRACTIONAL CRYSTALLIZATION IN THE HENRY’S FORK CALDERA OF THE YELLOWSTONE-SNAKE RIVER PLAIN AS REVEALED BY SR-ND-HF-PB ISOTOPES AND 40AR/39AR ERUPTION AGES." In Rocky Mountain Section - 73rd Annual Meeting - 2023. Geological Society of America, 2023. http://dx.doi.org/10.1130/abs/2023rm-387773.
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McIntosh, Eleanor Carmen, Michael Bizimis, and David A. Clague. "HF, ND, SR, PB ISOTOPE SYSTEMATICS OF REJUVENATED LAVAS FROM THE NORTH ARCH VOLCANIC FIELD." In 65th Annual Southeastern GSA Section Meeting. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016se-273472.
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Ramamurty, Prabala, Neethu Sukumaran, Teeda Kumar, and Gugulothu Balu. "Radiogenic Sr-Nd-Hf-Pb isotopic compositions of submarine volcanic rocks of a Seamount from the Andaman Sea." In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.18359.
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Grabarczyk-Gurba, Anna, Ewa Krzemińska, Leonid Shumlyanskyy, and Dominik Gurba. "A tentative model for the origin of anorthosite-gabbronorite Sejny Massif, NE Poland – Geochemistry, U–Pb ages, Sr–Nd and Hf–O isotopic composition." In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.16416.
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Yang, Yue-Heng. "High-Precision Sr-Nd-Hf-Pb Isotopic Composition of CGSG-1, CGSG-2, CGSG-4 and CGSG-5 Reference Materials by MC-ICP-MS and TIMS." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.3011.
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