[1]刘奕志,庞崇进,冯佐海.2018.桂东北晚震旦世-寒武纪砂岩物源特征: 对华南早古生代构造演化的制约.大地构造与成矿学,优先出版:001-25.doi:10.16539/j.ddgzyckx.2020.04.018
 LIU Yizhi,PANG Chongjin,FENG Zuohai.2018.Provenance of Late Sinian-Cambrian Sandstones in Northeastern Guangxi: Constraints on Early Paleozoic Tectonic Evolution of South China Block.Geotectonica et Metallogenia,优先出版:001-25.doi:10.16539/j.ddgzyckx.2020.04.018
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桂东北晚震旦世-寒武纪砂岩物源特征: 对华南早古生代构造演化的制约
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《大地构造与成矿学》[ISSN:ISSN 1001-1552/CN:CN 44-1595/P]

卷:
期数:
2018年优先出版
页码:
001-25
栏目:
出版日期:
2020-12-30

文章信息/Info

Title:
Provenance of Late Sinian-Cambrian Sandstones in Northeastern Guangxi: Constraints on Early Paleozoic Tectonic Evolution of South China Block
作者:
刘奕志 庞崇进 冯佐海 康志强 蓝健宁 朱家明 肖冰清 喻文亮
Author(s):
LIU Yizhi PANG Chongjin FENG Zuohai KANG Zhiqiang LAN Jianning ZHU Jiaming XIAO Bingqing and YU Wenliang
关键词:
晚震旦世-寒武纪 沉积地球化学 碎屑锆石U-Pb定年 扬子与华夏陆块界线 冈瓦纳大陆
Keywords:
Late Sinian-Cambrian sedimentary geochemistry detrital zircon U-Pb dating boundary between Yangtze and Cathaysia blocks gondwana continent
DOI:
10.16539/j.ddgzyckx.2020.04.018
文献标志码:
A
摘要:
桂东北位于南岭西段, 为江山-兴断裂带的南部延伸地带, 较好地保存了华南晚震旦世?武纪构造演化的沉积记录。本文对桂东北晚震旦世-寒武纪砂岩开展了岩相学、地球化学和碎屑锆石U-Pb年代学工作, 试图揭示其物质来源及地质意义。分析结果表明, 永福、贺州两地浅变质长石石英砂岩和石英杂砂岩具有富集轻稀土元素, 亏损重稀土元素, 弱Ce负异常, 明显Eu负异常的特征, 母岩以上地壳长英质岩石和再循环古老沉积物组分为主。地球化学构造判别图显示, 研究区在晚震旦世-寒武纪时可能处于类似被动大陆边缘的构造环境。永福地区晚震旦世砂岩中900~780 Ma的碎屑锆石含量丰富并少量出现2.0 Ga的锆石, 与扬子陆块具有明显的亲缘性; 但贺州地区晚震旦世砂岩以含大量~1.0 Ga碎屑锆石, 与华夏陆块具有明显的亲缘性。永福与贺州地区寒武纪砂岩中的碎屑锆石均以~1.0 Ga为主, 暗示其物源区在早-中寒武世前(>520 Ma)由扬子陆块转变为华夏陆块。结合古地理特征, 这一物源变化暗示早寒武世开始南华裂谷盆地逐渐变浅和缩小。受加里东期构造运动的影响, 扬子与华夏陆块于早?寒武世再次拼合, 其西南分界线可能从永福与贺州之间通过。依据碎屑锆石物源分析, 我们认为晚震旦世-寒武纪时期华南位于东冈瓦纳大陆北缘, 可能在印度北西缘的外围。
Abstract:
Late Sinian-Cambrian sandstones are well preserved in the northeastern area of the Guangxi Zhuang Autonomous Region, which is the western part of the Nanling Metallogenic Belt and the southern extension of the Jiangshan-Shaoxing fault zone, and can thus provide crucial information to constrain the Early Paleozoic tectonic evolution of South China Block. This study presents petrological, geochemical and geochronological data of the Late Sinian-Cambrian sandstones in order to reveal their provenance and to constrain the Early Paleozoic tectonic evolution of South China Block. Results show that the quartzofeldspathic sandstone and quartzose greywacke in the Yongfu and Hezhou areas are generally characterized by the enrichment of light Rare Earth Elements (REE), depletion of heavy REE, with negative Eu and Ce anomalies. The detritus could have been dominated by the recycled felsic igneous rocks and sedimentary components. Geochemical results suggest that the Late Sinian-Cambrian sandstones in the Yongfu and Hezhou areas may have been deposited in a tectonic setting that resembles passive continental margin. U-Pb ages of detrital zircon grains in the Yongfu Late Sinian sandstones peak at 900 – 780 Ma, with subordinated peak at 2.0 Ga, showing an affinity with the Yangtze block. The Cambrian sandstones in Yongfu area and the Late Sinian-Cambrian sandstones in Hezhou area are characterized by large amounts of ca.1.0 Ga detrital zircon grains, showing an affinity with the Cathaysia block. Combined with paleogeography, the shift of provenance of the Cambrian sandstones in Yongfu area suggests that the Nanhua rift basin became shallower and smaller during the Early Cambrian. The Yangtze block and the Cathaysia block began to assemblage again during the early-Middle Cambrian (>520 Ma), with a southwestern boundary between Yongfu and Hezhou areas. Based on detrital zircon provenance analyses, we propose that the South China Block was located at the periphery of the northwestern margin of India in East Gondwana during the Late Sinian to Cambrian.
更新日期/Last Update: 2020-09-15