| 浙西南遂昌—大柘地区八都岩群印支期变质变形序列 |
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| 引用本文： | 石磊,周喜文,郑常青,董云峰,周枭,郭腾达.浙西南遂昌—大柘地区八都岩群印支期变质变形序列[J].吉林大学学报(地球科学版),2019,49(6):1658-1671. |
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| 作者姓名： | 石磊 周喜文 郑常青 董云峰 周枭 郭腾达 |
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| 作者单位： | 1. 吉林大学地球科学学院, 长春 130061;2. 自然资源部东北亚矿产资源评价重点实验室, 长春 130061;3. 中国地质科学院地质研究所, 北京 100037 |
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| 基金项目： | 国家自然科学基金项目（41472164，41872192）；中国地质调查局地质调查项目（121201102000150020-06） |
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| 摘 要： | 浙西南遂昌-大柘地区八都岩群在印支期变质事件影响下发生变质变形，通过详细野外调查和岩相学研究，可将其划分为3期变质变形序列：S1变形期，NW向片麻理记录的残留紧闭褶皱，共生矿物组合为石榴子石变斑晶及其内部定向分布的包裹体矿物，石榴子石+黑云母+石英（泥质）和石榴子石+角闪石+斜长石+石英（长英质）；S2变形期，区域性宽缓褶皱及NE向缓倾透入性片麻理，共生矿物组合为石榴子石变斑晶及定向分布的基质矿物，矽线石+石榴子石+黑云母+石英+斜长石±钾长石（泥质）和石榴子石+钾长石+斜长石+黑云母+石英（长英质）；S3变形期，NE向陡倾透入性片麻理及韧脆性断裂大部分被花岗斑岩脉填充，共生矿物组合为石榴子石变斑晶及其周围退变矿物，石榴子石+矽线石+堇青石+斜长石+黑云母+石英±钾长石（泥质）和角闪石+斜长石+黑云母+钛铁矿（长英质）。结合前人研究成果，八都岩群印支期变质事件峰期变质程度达到麻粒岩相，显示顺时针近等温降压（ITD）型的p-T演化轨迹，S1-S3变质变形反映出从俯冲碰撞到快速折返冷却的演化过程，伴随S3同期侵位的花岗斑岩锆石U-Pb定年结果，将该演化过程完成时间约束在229.7 Ma，可能是浙西南地区对印支期古特提斯洋域内印支-华南-华北板块之间俯冲-碰撞过程的响应。
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| 关 键 词： | 八都岩群 变质变形序列 共生矿物组合 锆石U-Pb定年 浙西南 |
| 收稿时间： | 2019-03-03 |
Indosinian Metamorphic Deformation Sequence of Badu Group in Suichang-Dazhe Region,Southwestern Zhejiang |
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| Shi Lei,Zhou Xiwen,Zheng Changqing,Dong Yunfeng,Zhou Xiao,Guo Tengda.Indosinian Metamorphic Deformation Sequence of Badu Group in Suichang-Dazhe Region,Southwestern Zhejiang[J].Journal of Jilin Unviersity:Earth Science Edition,2019,49(6):1658-1671. |
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| Authors: | Shi Lei Zhou Xiwen Zheng Changqing Dong Yunfeng Zhou Xiao Guo Tengda |
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| Institution: | 1. College of Earth Sciences, Jilin University, Changchun 130061, China;2. Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Natural Resources, Changchun 130061, China;3. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China |
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| Abstract: | The Badu Group in Suichang-Dazhe region of southwestern Zhejiang underwent metamorphism and deformation under the influence of Indosinian metamorphic event. Through a detailed field investigation and lithofacies study, it can be divided into three metamorphism-deformation sequences:for S1 deformation period,the residual tight folds are recorded by NW-trending gneisses,and the symbiotic mineral assemblages are garnet metamorphic phenocrysts with inclusion minerals of garnet+biotite+quartz (argillaceous) and garnet + amphibole+plagioclase+quartz (feldspar) distributed directionally; for S2 deformation period,the regional wide-gentle folds and NE-trending gently inclined permeable gneisses are developed,and the symbiotic mineral assemblages are garnet metamorphic phenocrysts and matrix minerals of garnet+biotite+silica+quartz+K-feldspar+plagioclase (argillaceous) and garnet+K-feldspar+plagioclase+biotite+quartz (feldspar); for S3 deformation period,the NE-trending steeply inclined permeable gneisses and ductile-brittle fractures are mostly filled by granite porphyry veins, and the symbiotic mineral assemblages are garnet metamorphic phenocrysts and their retrograde edge minerals of garnet+cordierite+sillimanite+plagioclase+biotite+quartz+K-feldspar (argillaceous) and amphibole+plagioclase+biotite+ilmenite (feldspar). Combined with the previous research results, the peak metamorphic degree of Indosinian metamorphic event of Badu Group reached granulite facies,showing a clockwise near isothermal decompression (ITD) type p-T evolution track. The S1-S3 metamorphism and deformation reflect the evolution from subduction collision to rapid re-cooling. The zircon U-Pb dating results of granite porphyry restrict the completion time of the evolution process to 229.7 Ma, which may be the response of southwestern Zhejiang to the subduction-collision between the Indosinian-South China-North China plate to the Paleo-Tethyan Ocean during Indosinian. |
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| Keywords: | Badu Group metamorphism-deformation sequence symbiotic mineral asse-mblages zircon U-Pb dating southwestern Zhejiang Province |
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