| Cenozoic Adakite-type Volcanic Rocks in Qiangtang, Tibet and Its Significance |
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| 作者姓名： | LIU Shen HU Ruizhong FENG Caixi CHI Xiaoguo LI Cai YANG Rihong WANG Tianwu and JIN WeiGuiyang Institute of Geochemistry Chinese Academy of Sciences Guiyang Guizhou E-mail: lliushen@hotmail.comGraduate School of the Chinese Academy of Sciences Beijing College of Earth Sciences Jilin University Changchun Jilin Aero Geophysical & Remote Sensing Center Beijing |
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| 作者单位： | LIU Shen，HU Ruizhong，FENG Caixia，CHI Xiaoguo，LI Cai，YANG Rihong，WANG Tianwu and JIN WeiGuiyang Institute of Geochemistry，Chinese Academy of Sciences，Guiyang，Guizhou 550002E-mail: lliushen@hotmail.comGraduate School of the Chinese Academy of Sciences，Beijing 100039College of Earth Sciences，Jilin University，Changchun，Jilin 130026Aero Geophysical & Remote Sensing Center，Beijing 100083 |
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| 基金项目： | 国家重点基础研究发展计划(973计划)，the Project of Knowledge Innovation sponsored by the Chinese Academy of Sciences，国家杰出青年科学基金 |
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| 摘 要： | Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in A12O3(15.09-15.64%) and Na2O (>3.6%), high Sr (649-885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg<0.35), weak Eu anomaly (Eu/Eu=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, εNd= -18.61-0.02), show that the magma resulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and the petrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau.
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| 关 键 词： | 新生代 埃达克火山岩 西藏 羌塘 英安岩 碱性岩 橄榄粗安岩 底侵作用 升降运动 下地壳 |
Cenozoic Adakite-type Volcanic Rocks in Qiangtang, Tibet and Its Significance |
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| Authors: | LIU Shen HU Ruizhong FENG Caixi CHI Xiaoguo LI Cai YANG Rihong WANG Tianwu and JIN WeiGuiyang Institute of Geochemistry Chinese Academy of Sciences Guiyang Guizhou E-mail: lliushen@hotmailcomGraduate School of the Chinese Academy of Sciences Beijing College of Earth Sciences Jilin University Changchun Jilin Aero Geophysical & Remote Sensing Center Beijing |
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| Abstract: | Abstract Volcanic rocks in the study area, including dache, trachyandesite and mugearite, belong to the intermediate‐acid, high‐K calc‐alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in Al2O3 (15.09–15.64%) and Na2O (>3.6%), high Sr (649–885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg#<0.35), weak Eu anomaly (Eu/Eu*=0.84‐0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062‐0.7079, 143Nd/144Nd=0.51166‐0.51253, εNd = ?18.61‐0.02), show that the magma resulted from partial melting (10%‐40%) of newly underplated basaltic lower crust under high pressure (1–4 GPa), and the pedogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau. |
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| Keywords: | Cenozoic lower crust high-K calc-alkaline volcanic rock underplating partial melting uplift of plateau Qiangtang Tibet |
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