| 龙门山中北段印支晚期构造活动:来自构造解析及碎屑锆石年代学的证据 |
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| 引用本文： | 沈桐,孟立丰,陈伟,余养里,周小军.龙门山中北段印支晚期构造活动:来自构造解析及碎屑锆石年代学的证据[J].地球科学,2021,46(5):1728-1736. |
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| 作者姓名： | 沈桐 孟立丰 陈伟 余养里 周小军 |
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| 作者单位： | 西南石油大学地球科学与技术学院,四川成都 610500 |
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| 基金项目： | 国家科技重大专项2017ZX05005-001-002国家自然科学基金项目41302165 |
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| 摘 要： | 晚三叠世是四川盆地演化过程中的重要阶段，该时期盆地西部经历了从被动大陆边缘向前陆盆地的演变.为进一步厘定龙门山中北段印支晚期构造的具体活动时间及活动强度，本研究选择龙门山前中北段某地震剖面进行构造几何分析，结果显示龙门山前中北段大规模的逆冲推覆很可能在须家河组四段沉积初期就已经出现，其恢复的推覆位移量至少达到11 km；另外针对研究区晚三叠世地层开展碎屑锆石U-Pb年代学以及沉积学分析，结果显示~800 Ma主峰及沉积学响应表明须家河组三段沉积时期研究区域地层中具有大量来自龙门山中段彭灌杂岩的碎屑物质，反映龙门山中北段基底在须家河组三段沉积时期已经局部隆升并为研究区提供物源.
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| 关 键 词： | 龙门山褶皱带 晚三叠世 逆冲推覆构造 平衡剖面恢复 碎屑锆石 U-Pb年代学 沉积学 |
| 收稿时间： | 2020-08-25 |
Tectonic Activities in Middle and North Sections of Longmenshan Thrust Belt during Late Indosinian: Evidence from Structural Analysis and Detrital Zircon Geochronology |
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| Shen Tong,Meng Lifeng,Chen Wei,Yu Yangli,Zhou Xiaojun.Tectonic Activities in Middle and North Sections of Longmenshan Thrust Belt during Late Indosinian: Evidence from Structural Analysis and Detrital Zircon Geochronology[J].Earth Science-Journal of China University of Geosciences,2021,46(5):1728-1736. |
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| Authors: | Shen Tong Meng Lifeng Chen Wei Yu Yangli Zhou Xiaojun |
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| Abstract: | It is wildly shared that the western Sichuan basin changed from passive continental margin to a foreland basin during the Late Triassic. In order to depict this transition process as well as the time and intensity of the tectonic activity of Longmenshan thrust belt during Late Indosinian, a seismic section in the middle part of Longmenshan thrust belt was used to perform structural geometric analysis. The results show that the large scale thrusting of Longmenshan probably occurred during the early stage of the deposition time of T3x4 and the total displacement was at least 11 km. This is also supported by the sedimentary record of the detrital zircon U-Pb age from the synchrous strata. The major age peak of ~800 Ma shows great affinity to the Pengguan complex and Baoxing complex from the middle section of Longmenshan belt. It is concluded that the basement in the middle part of Longmenshan belt was uplifted partly during T3x3 and provided materials for the western Sichuan basin. |
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