| 晚中生代沂沭断裂带左旋韧性剪切与岩浆迁移规律 |
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| 引用本文： | 李盛,倪金龙,张尚坤,申颖. 晚中生代沂沭断裂带左旋韧性剪切与岩浆迁移规律[J]. 现代地质, 2021, 35(3): 776-786. DOI: 10.19657/j.geoscience.1000-8527.2021.060 |
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| 作者姓名： | 李盛 倪金龙 张尚坤 申颖 |
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| 作者单位： | 1.山东科技大学 地球科学与工程学院, 山东 青岛 2665902.海洋矿产资源评价与探测技术功能实验室,青岛海洋科学与技术国家实验室,山东 青岛 2662373.山东省地质科学研究院,山东 济南 250013 |
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| 基金项目： | 国家自然科学基金项目“胶东半岛鹊山变质核杂岩剥蚀隆升与金成矿作用”(42072226);山东省自然科学基金项目“中部地壳脆-韧性转换带的变形规律及机制研究——以胶南造山带为例”(ZR2018MD010);“晚中生代郯庐断裂带山东段两侧盆地差异构造演化及成因机制”(ZR2017PD001);山东省科技厅重大专项“沂沭断裂带深部结构及对资源环境的影响”(2017CXGC1602) |
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| 摘 要： | 沂沭断裂带内部的岩浆侵入与断裂活动关系密切,开展沂沭断裂带内部岩浆年代学研究,对于沂沭断裂带构造背景研究具有积极的参考意义。选取沂沭断裂带内部的莒县浮来山正长岩体、边部的莒南官坊石英正长岩体及侵入该岩体的闪长玢岩脉,开展岩石学及年代学研究。首次发现晚中生代沂沭断裂带左旋韧性剪切,获得浮来山岩体的LA-ICP-MS锆石U-Pb年龄为(125.1±1.7) Ma,官坊岩体年龄为(125.6±2.0) Ma, 发生韧性变形的闪长玢岩脉年龄为(122.8±2.1) Ma。获得的125 Ma岩浆活动年龄与沂沭断裂带东侧的五莲变质核杂岩快速剥露(122~128 Ma)、诸城断陷盆地快速沉降的时间相吻合,该时期沂沭断裂带处于岩石圈减薄与破坏强烈的时期;闪长玢岩脉的122.8 Ma结晶年龄,与五莲变质核杂岩后构造岩体(石场、坊子岩体等)结晶年龄一致,该时期沂沭断裂带处于弱伸展状态,同时也说明胶东半岛岩石圈减薄具有时间上的一致性。晚中生代时期,沂沭断裂带两侧岩浆活动具有逆时针迁移的规律,这一规律可能与伊佐奈岐板块向欧亚板块俯冲的方向、角度、速度的变换有关。
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| 关 键 词： | 沂沭断裂带 浮来山岩体 官坊岩体 晚中生代 U-Pb定年 |
| 收稿时间： | 2020-11-19 |
| 修稿时间： | 2021-04-23 |
Sinistral Ductile Shear and Magmatic Migration Pattern in the Late Mesozoic Yishu Fault Zone |
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| LI Sheng,NI Jinlong,ZHANG Shangkun,SHEN Ying. Sinistral Ductile Shear and Magmatic Migration Pattern in the Late Mesozoic Yishu Fault Zone[J]. Geoscience of Geosciences, 2021, 35(3): 776-786. DOI: 10.19657/j.geoscience.1000-8527.2021.060 |
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| Authors: | LI Sheng NI Jinlong ZHANG Shangkun SHEN Ying |
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| Affiliation: | 1. College of Geological Science and Engineering, Shandong University of Science and Technology, Qingdao, Shandong 266590, China2. Laboratory for Marine Mineral Resources, Pilot National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China3. Shandong Institute of Geological Sciences, Jinan, Shandong 250013, China |
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| Abstract: | Magma intrusion in the Yishu fault zone (YFZ) is closely related to fault activity, and the magmatic geochronology in the Yishu fault zone is of major significance for revealing the tectonic setting of the YFZ. Petrological and LA-ICP MS zircon U-Pb geochronological analyses were conducted on the Fulaishan syenite (in Juxian) in the Yishu fault zone, as well as the Guanfang quartz syenite (in Junan) and the intruding diorite porphyrite dykes. The sinistral ductile shearing of the Late Mesozoic YFZ was first recognized. Zircon U-Pb dating yielded (125.1±1.7) Ma (Fulaishan pluton), (125.6±2.0) Ma (Guanfang pluton), and (122.8±2.1) Ma (ductile-deformed diorite porphyrite dyke). The 125 Ma magmatic age obtained is consistent with the rapid exhumation (122-128 Ma) of the Wulian metamorphic core complex (MCC) and the rapid sedimentation in the Zhucheng fault-bounded basin on the eastern side of the YFZ. This indicates that the YFZ was in a period of intense lithospheric thinning and destruction. The 122.8 Ma age of the diorite porphyrite dike is consistent with the crystallization age of the post-Wulian MCC (e.g., Shichang and Fangzi plutons), indicating that the extension of the YFZ was significantly weakened during this period. It also shows the similar timing of lithospheric thinning across the Jiaodong Peninsula. During the Late Mesozoic, magmatism on both sides of the YFZ had a counterclockwise migration pattern, which may have related to the changing direction, angle, and/or velocity of the Izanagi plate subduction beneath the Eurasian plate. |
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| Keywords: | Yishu fault zone Fulaishan intrusion Guanfang intrusion Late Mesozoic zircon U-Pb dating |
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