| 中国东南部晚中生代基性岩脉地幔源区的岩性演化历史 |
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| 引用本文： | 雷祝梁,曾罡,王小均,陈立辉.中国东南部晚中生代基性岩脉地幔源区的岩性演化历史[J].地球科学,2019,44(4):1159-1168. |
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| 作者姓名： | 雷祝梁 曾罡 王小均 陈立辉 |
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| 作者单位： | 南京大学地球科学与工程学院, 内生金属矿床成矿机制研究国家重点实验室, 江苏南京 210023 |
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| 基金项目： | 国家自然科学基金项目41672048 |
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| 摘 要： | 中国东南部晚中生代的岩浆活动被认为与古太平洋板块的俯冲作用密切相关，而板块的俯冲作用又势必会对地幔的性质产生重要影响.晚中生代基性岩脉在中国东南部尤其是沿海地区广泛分布，为揭示中国东南部地幔演化历史及其与古太平洋板块俯冲之间的潜在成因联系提供了理想的研究对象.因此，对湘、赣、浙、闽、粤五省基性岩脉的年代学和地球化学数据进行了总结，通过恢复它们的原始岩浆组成，厘定其地幔源区岩性，揭示了研究区地幔的岩性演化历史.研究发现，中国东南部晚中生代基性岩脉的源区岩性在地域上没有显著差异，在时间尺度上表现出明显变化.在150~110 Ma期间，中国东南部地幔源区的岩性包含富硅辉石岩和贫硅辉石岩两类；而在110~64 Ma期间，地幔源区的主体岩性转变为贫硅辉石岩，伴随部分橄榄岩.基于上述地幔岩性的演化规律，并结合前人对研究区基性玄武岩的研究工作，认为研究区晚中生代地幔的岩性转变主要受控于古太平洋板块的俯冲过程，是板块俯冲角度改变的结果.
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| 关 键 词： | 基性岩脉 原始岩浆 源区岩性 古太平洋板块 中国东南部 岩石学 |
| 收稿时间： | 2018-12-19 |
Mantle Source Lithology of Late Mesozoic Mafic Dikes in Southeastern China |
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| Abstract: | Late Mesozoic magmatism in southeastern China was controlled by the subduction of paleo-Pacific plate, and the mantle beneath the area should also have been affected by such process.Late Mesozoic mafic dikes are widely distributed in southeastern China, especially in the coastal areas, which provide an ideal setting for studying the mantle evolution and subduction process of paleo-Pacific plate. Here it summarizes the chronological and geochemical data of mafic dikes in Hunan, Jiangxi, Zhejiang, Fujian and Guangdong provinces. Source lithologies of these rocks are identified by the compositions of fractionation-corrected primary magmas. The study indicates that the mantle lithologies of these mafic dikes in southeastern China do not show obvious differences in space, but significant changes with time. The source lithologies of mafic dikes during the period of 150-110 Ma are composed of SiO2-rich pyroxenite and SiO2-poor pyroxenite, whereas the source lithologies during 110-64 Ma are primarily composed of SiO2-poor pyroxenite, with minor peridotite. Therefore, it is suggested that the lithological variation of Late Mesozoic mantle beneath southeastern China is controlled by the subduction of paleo-Pacific plate via the variation of the subduction angle. |
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