| 浙西北地区寒武系物源分析及古地理意义:来自沉积学及碎屑锆石年代学的证据 |
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| 引用本文： | 于涛,王宗起,马昌前,王东升,王涛,黄凡.浙西北地区寒武系物源分析及古地理意义:来自沉积学及碎屑锆石年代学的证据[J].地质学报,2021,95(11):3266-3281. |
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| 作者姓名： | 于涛 王宗起 马昌前 王东升 王涛 黄凡 |
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| 作者单位： | 中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京,100037;中国地质大学(武汉)地球科学学院,湖北武汉,430074;中国地质调查局发展研究中心,北京,100037;中国地质大学(武汉)地球科学学院,湖北武汉,430074;中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京,100037;中国地质科学院地质研究所,北京,100037 |
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| 基金项目： | 本文为国家重点研发计划(编号2016YFC0600202)、国家自然科学基金项目(编号41702213)、中国地质科学院基本科研业务费专项经费(编号JYYWF20183701)和中国地质调查局项目(编号DD20190398)联合资助的成果。 |
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| 摘 要： | 浙西北地区寒武系沉积环境及物源分析是重建扬子板块东南缘古地理格局的关键,进而可以为华南大地构造演化提供证据.本文根据沉积相时空展布、斜层理与同沉积褶皱恢复的物源方向以及碎屑锆石LA-ICP-MSU-Pb测年,综合探讨寒武系的陆源碎屑物源方向以及物源区.浙西北地区寒武纪地层主要由碳硅质岩、硅质页岩、砾屑灰岩、砂屑灰岩、泥灰岩、泥岩等组成.沉积序列、沉积相标志研究表明,寒武系沉积构造以泄水构造、滑塌褶曲、流动构造、层间滑动、同沉积褶皱和断层等为特征,发育大量滑塌沉积及碳酸盐岩浊积岩,整体为深水盆地及斜坡环境.沉积相时空展布及古流向研究表明,水体向北西方向加深,寒武系陆源碎屑物质主要来源于南东方向,非前人通过古生物地层判断的盆地基底北西高南东低.碎屑锆石年代学研究表明,物源集中于574 Ma、747 Ma、1768 Ma以及2131 Ma,与邻区碎屑锆石年龄图谱对比分析表明,江山-绍兴断裂带及浙江中部地区为主要物源区,陆缘碎屑物质主要来自于陈蔡群、双溪坞群、河上镇群及八都群.寒武纪时期,斜坡盆地沉积基底向北西倾斜,位于盆地西北部的章里地区为沉积中心,华夏地块露出水面为剥蚀区.
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| 关 键 词： | 沉积环境 物源分析 浙西北 寒武系 古地理 |
| 收稿时间： | 2020/8/8 0:00:00 |
| 修稿时间： | 2020/9/7 0:00:00 |
Provenance analysis and paleogeographic significance of the Cambrian in NW Zhejiang: evidence from sedimentology and detrital zircon chronology |
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| Yu Tao,Wang Zongqi,Ma Changqian,Wang Dongsheng,Wang Tao,Huang Fan.Provenance analysis and paleogeographic significance of the Cambrian in NW Zhejiang: evidence from sedimentology and detrital zircon chronology[J].Acta Geologica Sinica,2021,95(11):3266-3281. |
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| Authors: | Yu Tao Wang Zongqi Ma Changqian Wang Dongsheng Wang Tao Huang Fan |
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| Abstract: | The Cambrian sedimentary environment and provenance analysis in NW Zhejiang is the key to reconstructing the paleogeography of the SE margin of the Yangtze block, which can provide evidence for the tectonic evolution of the South China Block. Based on the sedimentary facies distribution, paleocurrent direction restored by cross bedding and syndepositional slump folds, and detrital zircon LA- ICP- MS U- Pb dating, the provenance direction and source areas of terrigenous clastics in the Cambrian were comprehensively discussed. The Cambrian strata in NW Zhejiang are mainly composed of carbon siliceous rock, siliceous shale, calcirudyte, sandy limestone,marlstone and mudstone. Sedimentary sequences and facies markers show that the Cambrian strata of the NW Zhejiang are characterized by water- escape structures,slump- folds, flow structures, interformational sliding, syndepositional folds and faults. The Cambrian strata develop olistostromes and carbonate turbidities, indicating that the deposition occurred in deepwater basin and slope environment. The temporal and spatial distribution of sedimentary facies as well as the direction of paleocurrents reflect that the basin deepens to the northwest, and the continental clastic materials of Cambrian mainly came from the southeast, rather than the sedimentary basement inclined toward the southeast judged by paleontological stratigraphy. The Cambrian samples yielded four primary detrital zircon U- Pb age populations of ca. 574 Ma, ca. 747 Ma, ca. 1768 Ma and ca. 2131 Ma, the result of spectrum correlation suggests that the Jiangshan- Shaoxing fault zone and the central Zhejiang area were the main source area, and the terrigenous clastics derived mainly from the Chencai Group, the Shuangxiwu Group, the Heshangzhen Group and the Badu Group. During the Cambrian period, the sedimentary basement inclined toward the northwest, the Zhangli area in the northwest of the basin was the depocenter, and the Cathaysia block emerged above the water as a denuded zone. |
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| Keywords: | sedimentary environment provenance analysis NW Zhejiang Cambrian paleogeography |
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