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Yinqi Li - One of the best experts on this subject based on the ideXlab platform.
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estimating the parental Magma composition and temperature of the xiaohaizi cumulate bearing ultramafic rock implication for Magma Evolution of the tarim large igneous province northwestern china
Journal of Earth Science, 2016Co-Authors: Yinqi Li, Zilong Li, Charles H Langmuir, Hanlin Chen, Shufeng YangAbstract:The ultramafic dikes in the Tarim large igneous province (Tarim LIP), exposed in the Xiaohaizi area in the northwestern Tarim Basin of northwestern China, have porphyritic textures, and the olivine and clinopyroxene are as the major phenocryst phases. The groundmass therein consists of clinopyroxene, plagioclase and Fe-Ti oxides, with the cryptocrystalline texture. The olivine phenocrysts in one typical ultramafic dike have Fo (Mg/(Mg+Fe)) numbers ranging from 73 to 85, which are not in equilibrium with the olivine (Mg# of 89) from the host rock crystalized. Combined with microscope observation, both the olivine and clinopyroxene phenocrysts as well as some Fe-Ti oxides in the ultramafic rock are accounted as cumulates. The liquid (parental Magma) composition of SiO2 of 45.00 wt.%–48.82 wt.%, MgO of 9.93 wt.%–18.56 wt.%, FeO of 5.85 wt.%–14.17 wt.%, CaO of 7.54 wt.%–11.52 wt.%, Al2O3 of 8.70 wt.%–11.62 wt.% and TiO2 of 0.00 wt.%–3.43 wt.% in the Xiaohaizi ultramafic rock was estimated by mass balance, and the results show a reasonable liquid proportion in the cumulate-bearing ultramafic dike (ca. 45%–60% in the whole rock). The estimated parental Magma composition corresponds to a melting temperature of 1 300–1 550 oC, which is equal or higher than those of a normal asthenosphere mantle, supporting the involvement of a mantle plume. Combined with other previous studies, an Evolution model for the formation processes of the Xiaohaizi ultramafic dike of the Tarim LIP is proposed.
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origin of the early permian zircons in keping basalts and Magma Evolution of the tarim large igneous province northwestern china
Lithos, 2014Co-Authors: Yinqi Li, Zilong Li, Charles H Langmuir, Hanlin Chen, Shufeng Yang, Xing Yu, M Santosh, Zhongli TangAbstract:Abstract The Tarim continental flood basalts (CFBs) provide important clues about the genesis and Magmatic Evolution of the Early Permian Tarim Large Igneous Province (Tarim LIP) in northwestern China. Here we present results of LA–MC–ICPMS Lu–Hf isotope analysis on Early Permian (ca. 290 Ma) zircons extracted from the Tarim CFBs in the Keping area, northwest of the Tarim Basin. Zircons from two sub-groups of Keping basalts (Groups 1a and 1b) have similar Lu–Hf isotopic compositions and exhibit a relatively large range of 176 Hf/ 177 Hf ratios between 0.282422 and 0.282568. Their negative e Hf ( t ) values (− 6.8–− 1.4) are generally lower than the whole-rock e Hf ( t ) values of their host basalts (− 2.8–2.1), and are distinct from other known intrusive rocks (− 0.3–7.1) in the Tarim LIP and their hosted zircons (4.9–8.8). Systematic studies of Hf isotopic data from Tarim and its adjacent regions reveal that these zircons are probably xenocrysts, sourced from coeval igneous rocks in the South Tianshan Orogen (e.g., the Lower Permian Xiaotikanlike Formation volcanic and pyroclastic rock suite). This, together with the presence of Precambrian zircons in Keping basalts, clearly indicates crustal contamination during their eruptions and provides hints about the potential contaminant sources. Geochemical modeling further suggests that the earlier erupted Group 1b basalts experienced more contamination, predominantly by some high Th–U–Pb rock components, most likely from the South Tianshan Orogen. The later erupted Group 1a basalts in the Keping area have been less contaminated with mainly the Tarim Precambrian rocks. Another group of the Tarim CFBs in the Northern Tarim Uplift (Group 2) appears to have undergone negligible crustal contamination but possesses evidence for variable source compositions. The modeling also indicates that the uncontaminated parental Magmas of various Tarim LIP rocks (from the picrites and basalts to ultramafic–mafic and syenitic intrusive rocks) exhibit a wide range of e Nd ( t ) values (ca. − 5–5), reflecting source isotopic heterogeneity, which may be a consequence of plume–lithosphere interaction during the generation of the Tarim LIP.
Zhongli Tang - One of the best experts on this subject based on the ideXlab platform.
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origin of the early permian zircons in keping basalts and Magma Evolution of the tarim large igneous province northwestern china
Lithos, 2014Co-Authors: Yinqi Li, Zilong Li, Charles H Langmuir, Hanlin Chen, Shufeng Yang, Xing Yu, M Santosh, Zhongli TangAbstract:Abstract The Tarim continental flood basalts (CFBs) provide important clues about the genesis and Magmatic Evolution of the Early Permian Tarim Large Igneous Province (Tarim LIP) in northwestern China. Here we present results of LA–MC–ICPMS Lu–Hf isotope analysis on Early Permian (ca. 290 Ma) zircons extracted from the Tarim CFBs in the Keping area, northwest of the Tarim Basin. Zircons from two sub-groups of Keping basalts (Groups 1a and 1b) have similar Lu–Hf isotopic compositions and exhibit a relatively large range of 176 Hf/ 177 Hf ratios between 0.282422 and 0.282568. Their negative e Hf ( t ) values (− 6.8–− 1.4) are generally lower than the whole-rock e Hf ( t ) values of their host basalts (− 2.8–2.1), and are distinct from other known intrusive rocks (− 0.3–7.1) in the Tarim LIP and their hosted zircons (4.9–8.8). Systematic studies of Hf isotopic data from Tarim and its adjacent regions reveal that these zircons are probably xenocrysts, sourced from coeval igneous rocks in the South Tianshan Orogen (e.g., the Lower Permian Xiaotikanlike Formation volcanic and pyroclastic rock suite). This, together with the presence of Precambrian zircons in Keping basalts, clearly indicates crustal contamination during their eruptions and provides hints about the potential contaminant sources. Geochemical modeling further suggests that the earlier erupted Group 1b basalts experienced more contamination, predominantly by some high Th–U–Pb rock components, most likely from the South Tianshan Orogen. The later erupted Group 1a basalts in the Keping area have been less contaminated with mainly the Tarim Precambrian rocks. Another group of the Tarim CFBs in the Northern Tarim Uplift (Group 2) appears to have undergone negligible crustal contamination but possesses evidence for variable source compositions. The modeling also indicates that the uncontaminated parental Magmas of various Tarim LIP rocks (from the picrites and basalts to ultramafic–mafic and syenitic intrusive rocks) exhibit a wide range of e Nd ( t ) values (ca. − 5–5), reflecting source isotopic heterogeneity, which may be a consequence of plume–lithosphere interaction during the generation of the Tarim LIP.
Mary R. Reid - One of the best experts on this subject based on the ideXlab platform.
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Accessory mineral U–Th–Pb ages and ^40Ar/^39Ar eruption chronology, and their bearing on rhyolitic Magma Evolution in the Pleistocene Coso volcanic field, California
Contributions to Mineralogy and Petrology, 2009Co-Authors: Justin I. Simon, Charles R Bacon, Jorge A Vazquez, Axel K Schmitt, Paul R. Renne, Mary R. ReidAbstract:We determined Ar/Ar eruption ages of eight extrusions from the Pleistocene Coso volcanic field, a long-lived series of small volume rhyolitic domes in eastern California. Combined with ion-microprobe dating of crystal ages of zircon and allanite from these lavas and from granophyre geothermal well cuttings, we were able to track the range of Magma-production rates over the past 650 ka at Coso. In ≤230 ka rhyolites we find no evidence of protracted Magma residence or recycled zircon (or allanite) from Pleistocene predecessors. A significant subset of zircon in the ~85 ka rhyolites yielded ages between ~100 and 200 Ma, requiring that generation of at least some rhyolites involves material from Mesozoic basement. Similar zircon xenocrysts are found in an ~200 ka granophyre. The new age constraints imply that Magma Evolution at Coso can occur rapidly as demonstrated by significant changes in rhyolite composition over short time intervals (≤10’s to 100’s ka). In conjunction with radioisotopic age constraints from other young silicic volcanic fields, dating of Coso rhyolites highlights the fact that at least some (and often the more voluminous) rhyolites are produced relatively rapidly, but that many small-volume rhyolites likely represent separation from long-lived mushy Magma bodies.
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accessory mineral u th pb ages and 40ar 39ar eruption chronology and their bearing on rhyolitic Magma Evolution in the pleistocene coso volcanic field california
Contributions to Mineralogy and Petrology, 2009Co-Authors: Justin I. Simon, Charles R Bacon, Jorge A Vazquez, Axel K Schmitt, Paul R. Renne, Mary R. ReidAbstract:We determined Ar/Ar eruption ages of eight extrusions from the Pleistocene Coso volcanic field, a long-lived series of small volume rhyolitic domes in eastern California. Combined with ion-microprobe dating of crystal ages of zircon and allanite from these lavas and from granophyre geothermal well cuttings, we were able to track the range of Magma-production rates over the past 650 ka at Coso. In ≤230 ka rhyolites we find no evidence of protracted Magma residence or recycled zircon (or allanite) from Pleistocene predecessors. A significant subset of zircon in the ~85 ka rhyolites yielded ages between ~100 and 200 Ma, requiring that generation of at least some rhyolites involves material from Mesozoic basement. Similar zircon xenocrysts are found in an ~200 ka granophyre. The new age constraints imply that Magma Evolution at Coso can occur rapidly as demonstrated by significant changes in rhyolite composition over short time intervals (≤10’s to 100’s ka). In conjunction with radioisotopic age constraints from other young silicic volcanic fields, dating of Coso rhyolites highlights the fact that at least some (and often the more voluminous) rhyolites are produced relatively rapidly, but that many small-volume rhyolites likely represent separation from long-lived mushy Magma bodies.
Shufeng Yang - One of the best experts on this subject based on the ideXlab platform.
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estimating the parental Magma composition and temperature of the xiaohaizi cumulate bearing ultramafic rock implication for Magma Evolution of the tarim large igneous province northwestern china
Journal of Earth Science, 2016Co-Authors: Yinqi Li, Zilong Li, Charles H Langmuir, Hanlin Chen, Shufeng YangAbstract:The ultramafic dikes in the Tarim large igneous province (Tarim LIP), exposed in the Xiaohaizi area in the northwestern Tarim Basin of northwestern China, have porphyritic textures, and the olivine and clinopyroxene are as the major phenocryst phases. The groundmass therein consists of clinopyroxene, plagioclase and Fe-Ti oxides, with the cryptocrystalline texture. The olivine phenocrysts in one typical ultramafic dike have Fo (Mg/(Mg+Fe)) numbers ranging from 73 to 85, which are not in equilibrium with the olivine (Mg# of 89) from the host rock crystalized. Combined with microscope observation, both the olivine and clinopyroxene phenocrysts as well as some Fe-Ti oxides in the ultramafic rock are accounted as cumulates. The liquid (parental Magma) composition of SiO2 of 45.00 wt.%–48.82 wt.%, MgO of 9.93 wt.%–18.56 wt.%, FeO of 5.85 wt.%–14.17 wt.%, CaO of 7.54 wt.%–11.52 wt.%, Al2O3 of 8.70 wt.%–11.62 wt.% and TiO2 of 0.00 wt.%–3.43 wt.% in the Xiaohaizi ultramafic rock was estimated by mass balance, and the results show a reasonable liquid proportion in the cumulate-bearing ultramafic dike (ca. 45%–60% in the whole rock). The estimated parental Magma composition corresponds to a melting temperature of 1 300–1 550 oC, which is equal or higher than those of a normal asthenosphere mantle, supporting the involvement of a mantle plume. Combined with other previous studies, an Evolution model for the formation processes of the Xiaohaizi ultramafic dike of the Tarim LIP is proposed.
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origin of the early permian zircons in keping basalts and Magma Evolution of the tarim large igneous province northwestern china
Lithos, 2014Co-Authors: Yinqi Li, Zilong Li, Charles H Langmuir, Hanlin Chen, Shufeng Yang, Xing Yu, M Santosh, Zhongli TangAbstract:Abstract The Tarim continental flood basalts (CFBs) provide important clues about the genesis and Magmatic Evolution of the Early Permian Tarim Large Igneous Province (Tarim LIP) in northwestern China. Here we present results of LA–MC–ICPMS Lu–Hf isotope analysis on Early Permian (ca. 290 Ma) zircons extracted from the Tarim CFBs in the Keping area, northwest of the Tarim Basin. Zircons from two sub-groups of Keping basalts (Groups 1a and 1b) have similar Lu–Hf isotopic compositions and exhibit a relatively large range of 176 Hf/ 177 Hf ratios between 0.282422 and 0.282568. Their negative e Hf ( t ) values (− 6.8–− 1.4) are generally lower than the whole-rock e Hf ( t ) values of their host basalts (− 2.8–2.1), and are distinct from other known intrusive rocks (− 0.3–7.1) in the Tarim LIP and their hosted zircons (4.9–8.8). Systematic studies of Hf isotopic data from Tarim and its adjacent regions reveal that these zircons are probably xenocrysts, sourced from coeval igneous rocks in the South Tianshan Orogen (e.g., the Lower Permian Xiaotikanlike Formation volcanic and pyroclastic rock suite). This, together with the presence of Precambrian zircons in Keping basalts, clearly indicates crustal contamination during their eruptions and provides hints about the potential contaminant sources. Geochemical modeling further suggests that the earlier erupted Group 1b basalts experienced more contamination, predominantly by some high Th–U–Pb rock components, most likely from the South Tianshan Orogen. The later erupted Group 1a basalts in the Keping area have been less contaminated with mainly the Tarim Precambrian rocks. Another group of the Tarim CFBs in the Northern Tarim Uplift (Group 2) appears to have undergone negligible crustal contamination but possesses evidence for variable source compositions. The modeling also indicates that the uncontaminated parental Magmas of various Tarim LIP rocks (from the picrites and basalts to ultramafic–mafic and syenitic intrusive rocks) exhibit a wide range of e Nd ( t ) values (ca. − 5–5), reflecting source isotopic heterogeneity, which may be a consequence of plume–lithosphere interaction during the generation of the Tarim LIP.
Hollings P - One of the best experts on this subject based on the ideXlab platform.
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Multi-stage arc Magma Evolution recorded by apatite in volcanic rocks
'Geological Society of America', 2020Co-Authors: Nathwani Chetan, Buret Y, Jj Wilkinson, Rh Sievwright, Hollings PAbstract:Gold open access fee paid by NHMProtracted Magma storage in the deep crust is a key stage in the formation of evolved, hydrous arc Magmas that can result in explosive volcanism and the formation of economically valuable Magmatic-hydrothermal ore deposits. High Magmatic water content in the deep crust results in extensive amphibole ± garnet fractionation and the suppression of plagioclase crystallization as recorded by elevated Sr/Y ratios and high Eu (high Eu/Eu*) in the melt. Here, we use a novel approach to track the petrogenesis of arc Magmas using apatite trace element chemistry in volcanic formations from the Cenozoic arc of central Chile. These rocks formed in a Magmatic cycle that culminated in high-Sr/Y Magmatism and porphyry ore deposit formation in the Miocene. We use Sr/Y, Eu/Eu*, and Mg in apatite to track discrete stages of arc Magma Evolution. We apply fractional crystallization modeling to show that early-crystallizing apatite can inherit a high-Sr/Y and high-Eu/Eu* melt chemistry signature that is predetermined by amphibole-dominated fractional crystallization in the lower crust. Our modeling shows that crystallization of the in situ host-rock mineral assemblage in the shallow crust causes competition for trace elements in the melt that leads to apatite compositions diverging from bulk-Magma chemistry. Understanding this decoupling behavior is important for the use of apatite as an indicator of metallogenic fertility in arcs and for interpretation of provenance in detrital studies.© 2020 The Authors Gold Open Access: This paper is published under the terms of the CC-BY license (https://creativecommons.org/licenses/by/4.0/). The attached file is the published pdf
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Multi-stage arc Magma Evolution recorded by apatite in volcanic rocks
'Geological Society of America', 2019Co-Authors: Nathwani C, Loader M, Wilkinson J, Buret Y, Sievwright R, Hollings PAbstract:Protracted Magma storage in the deep crust is a key stage in the formation of evolved, hydrous arc Magmas that can result in explosive volcanism and the formation of economically valuable Magmatic13 hydrothermal ore deposits. High Magmatic water content in the deep crust results in extensive amphibole ± garnet fractionation and the suppression of plagioclase crystallization as recorded by elevated Sr/Y ratios and high Eu (high Eu/Eu*) in the melt. Here, we use a novel approach to track the petrogenesis of arc Magmas using apatite trace element chemistry in volcanic formations from the Cenozoic arc of Central Chile. These rocks formed in a Magmatic cycle that culminated in high Sr/Y Magmatism and porphyry ore deposit formation in the Miocene. We use Sr/Y, Eu/Eu* and Mg in apatite to track discrete stages of arc Magma Evolution. We apply fractional crystallization modeling to show that early crystallizing apatite inherits a high Sr/Y and Eu/Eu* melt chemistry signature that is predetermined by amphibole-dominated fractional crystallization in the lower crust. Our modeling shows that crystallization of the in-situ host rock mineral assemblage in the shallow crust causes competition for trace elements in the melt that leads to apatite compositions diverging from bulk Magma chemistry. Understanding this decoupling behavior is important for the use of apatite as an indicator of metallogenic fertility in arcs and for interpretation of provenance in detrital studies
