| Petrogenesis of the Neoproterozoic bimodal volcanic rocks along the western margin of the Yangtze Block： New constraints from Hf isotopes and Fe/Mn ratios |
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| 作者姓名： | LI Xianhua QI Changshi LIU Ying LIANG Xirong TU Xianglin XlE Liewen YANG Yueheng |
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| 作者单位： | [1]Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China [2]Graduate University of Chinese Academy of Sciences, Beijing 100039, China [3]Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China |
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| 基金项目： | This paper benefits from the critical and constructive review comments by Drs. Wu Fuyuan, Sun Weidong, Zou Haibo, Qin Liping and Zheng Yongfei at different early stages. This work was supported by NSFC （Grant No. 40421303） and Chinese Academy of Sciences （Grant Nos. KZCX3-SW-141 and GIGCX-04-06）. |
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| 摘 要： | High-precision major element and Hf isotope data are reported for the Neoproterozoic Suxiong volcanic rocks along the western margin of the Yangtze Block. These volcanic rocks have variable εHf（T） values and Fe/Mn ratios. The relatively primitive basalts have high Fe/Mn ratios and high Hf-Nd isotopic compositions, indicating that they were generated by partial melting of garnet clinopyroxene in mantle plume at high pressure. Thus, the Suxiong basalts are genetically related to the proposed Neoproterozoic superplume. On the contrary, a few differentiated basalts have low Fe/Mn ratios and low Hf-Nd isotopic compositions. They are likely to experience assimilation-fractional crystallization process. The Suxiong rhyolites have consistent Hf and Nd model ages of 1.3-1.4 Ga. They are likely generated by shallow dehydration melting of pre-existing young arc igneous rocks associated with the basaltic underplating/intrusion in a continental rift.
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| 关 键 词： | 火山岩 页岩 同位素 玄武岩 岩石学 |
| 收稿时间： | 2005-06-08 |
| 修稿时间： | 2005-06-082005-08-01 |
Petrogenesis of the Neoproterozoic bimodal volcanic rocks along the western margin of the Yangtze Block: New constraints from Hf isotopes and Fe/Mn ratios |
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| LI Xianhua QI Changshi LIU Ying LIANG Xirong TU Xianglin XlE Liewen YANG Yueheng.Petrogenesis of the Neoproterozoic bimodal volcanic rocks along the western margin of the Yangtze Block: New constraints from Hf isotopes and Fe/Mn ratios[J].Chinese Science Bulletin,2005,50(21):2481-2486. |
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| Authors: | Email author" target="_blank">Xianhua?LiEmail author Changshi?Qi Ying?Liu Xirong?Liang Xianglin?Tu Liewen?Xie Yueheng?Yang |
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| Institution: | LI Xianhua1, QI Changshi1,2, LIU Ying1, LIANG Xirong1, TU Xianglin1, XIE Liewen3 & YANG Yueheng3 1. Key Laboratory of Isotope Geochronology and Geochemistry, Guang-zhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; 2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China; 3. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China |
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| Abstract: | High-precision major element and Hf isotope data are reported for the Neoproterozoic Suxiong volcanic rocks along the western
margin of the Yangtze Block. These volcanic rocks have variable εHf(T) values and Fe/Mn ratios. The relatively primitive basalts have high Fe/Mn ratios and high Hf-Nd isotopic compositions, indicating
that they were generated by partial melting of garnet clinopyroxene in mantle plume at high pressure. Thus, the Suxiong basalts
are genetically related to the proposed Neoproterozoic superplume. On the contrary, a few differentiated basalts have low
Fe/Mn ratios and low Hf-Nd isotopic compositions. They are likely to experience assimilation-fractional crystallization process.
The Suxiong rhyolites have consistent Hf and Nd model ages of 1.3–1.4 Ga. They are likely generated by shallow dehydration
melting of pre-existing young arc igneous rocks associated with the basaltic underplating/intrusion in a continental rift. |
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| Keywords: | Hf isotope Fe/Mn basalt rhyolite Yangtze Block Neoproterozoic mantle plume |
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