| 江山-绍兴构造带陈蔡岩群斜长角闪岩变质时代、地球化学特征及其构造演化意义 |
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| 引用本文： | 陈林燊,陈汉林,龚俊峰,章凤奇,孟立丰,林秀斌,杨树锋.江山-绍兴构造带陈蔡岩群斜长角闪岩变质时代、地球化学特征及其构造演化意义[J].地球科学,2019,44(4):1216-1235. |
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| 作者姓名： | 陈林燊 陈汉林 龚俊峰 章凤奇 孟立丰 林秀斌 杨树锋 |
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| 作者单位： | 浙江大学地球科学学院, 浙江杭州 310027 |
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| 基金项目： | 国家科技重大专项2017ZX05008001国家重点研发计划2016YFC0601004国家科技重大专项2016ZX05003001 |
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| 摘 要： | 目前前人对于陈蔡岩群的变质时限和形成环境的认识观点不一.斜长角闪岩作为陈蔡岩群的重要岩石单元，是认识整个陈蔡岩群原岩性质和构造演化最重要的窗口之一.对陈蔡岩群中的斜长角闪岩开展了详细的年代学和岩石地球化学研究.SHRIMP U-Pb定年结果显示，斜长角闪岩锆石加权平均年龄为424.0±3.6 Ma，代表了峰期变质事件时间，并保留了新元古代晚期到早古生代早期的变质年龄记录；地球化学特征和判别图解表明，陈蔡岩群斜长角闪岩原岩为洋岛碱性玄武岩，结合野外观察到的斜长角闪岩与大理岩密切共生现象，认为其原岩可能为一套来自洋岛-海山体系的洋岛玄武岩-碳酸盐岩组合.陈蔡岩群的原岩可能是在古南华洋板块向扬子板块俯冲过程中形成的增生楔岩石组合，在早古生代晚期经历了角闪岩相变质作用.
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| 关 键 词： | 陈蔡岩群 斜长角闪岩 锆石U-Pb定年 地球化学 洋岛玄武岩 构造演化 |
| 收稿时间： | 2018-04-21 |
Metamorphic Episodes,Geochemical Characteristics of Chencai Amphibolite and Its Tectonic Implications in Jiangshan-Shaoxing Fault Zone |
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| Abstract: | Currently, predecessors hold different views on metamorphic ages and formation background of the Chencai Group. As the representative rock unit of the Chencai Group, the amphibolite is an important window for understanding its protolith property and tectonic evolution. Therefore, in this paper in detailed it analyzes the amphibolite from the Chencai Group, including geochronology and whole rock geochemistry.SHRIMP U-Pb dating data from the amphibolite, the weighted mean age of 424.0±3.6 Ma records the timing of the main metamorphic event and simultaneously preserves the record of the metamorphic age from Late Neoproterozoic to Ordovician. Based on the geochemical characteristics and discrimination diagrams, it is proposed that the protolith of the amphibolite from the Chencai Group is ocean island alkali basalt (OIB). Field observation presents the paragenetic association of the amphibolite with marble, further implying that the protolith of the amphibolite-marble assemblage could be OIB-carbonate rock assemblage from the oceanic island-seamount system. The protolith of the Chencai Group is probably the rock assemblage of the accretionary wedge which formed in the subduction of the South China Proterozoic ocean beneath the Yangtze block. The amphibolite-facies metamorphism occurred in the late period of Early Paleozoic. |
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