| 摘要: |
| 新元古代-早古生代，Rodinia超大陆裂解至Gondwana大陆聚合的过程对华南构造格局与古地理演化具有重要的制约作用，然而在这过程中华夏地块的位置、华夏与扬子之间的关系等问题仍存在争议。本文通过同位素地层年代学、新元古代冰期事件及成矿事件对比了华夏地块武夷南部-南岭地区及华夏西缘新元古代中-晚期地层。在此基础上，对新元古代沉积物进行碎屑锆石物源分析，发现华夏西缘拉伸纪晚期-埃迪卡拉纪曾出现多次物源方向的转换，并在成冰纪晚期同时出现来自华南内部和外部的双向物源。结合浅海陆棚的沉积环境，表明此时扬子与华夏之间并没有宽阔的大洋相隔。华夏地块拉伸纪晚期-埃迪卡拉纪碎屑岩中包含了大量中元古代至新元古代早期的碎屑锆石，与东冈瓦纳北部印度、东南极等地区的沉积记录吻合，指示华夏地块至少自750 Ma时期就接收到来自印度北缘的碎屑物质。在Rodinia超大陆裂解至Gondwana大陆聚合期间，华南一直保持在超大陆边缘的古地理位置，与印度北缘相连。 |
| 关键词: 华夏地块 新元古代 物源分析 Rodinia超大陆 Gondwana大陆 |
| DOI：10.19826/j.cnki.1009-3850.2023.02017 |
| 附件 |
| 投稿时间：2022-12-31修订日期：2023-01-15 |
| 基金项目:国家自然科学基金项目（42102139、42172126） |
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| Neoproterozoic sedimentary records in the Cathaysia Block and their implications for the supercontinent reconstruction |
| QI Liang, XU Yajun, DU Yuansheng, HOU Mingcai |
(1. Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China;
2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China;
3. School of Earth Sciences, China University of Geosciences, Wuhan 430074, China) |
| Abstract: |
| The tectonic framework and paleogeographic evolution of Neoproterozoic-early Paleozoic successions in the South China Block provides the first-order constraint on its role in the break-up of Rodinia and the subsequent amalgamation of Gondwana. However, there still is much disagreement in defining the paleoposition of the Cathaysia Block and its relationship with the Yangtze Block. In this thesis, isotopic geochronology, Neoproterozoic glaciations, and mineralization records were found in the Cathaysia Block, providing new evidence for the stratigraphic framework. Detrital zircon U-Pb dating results provide evidence of prominent provenance transition during late Tonian to Ediacaran, and bidirectional sources in the western margin of Cathaysia Block at late Cryogenian, integrating with the evidence from a sedimentary environment of neritic shelf, a closure of paleo-South China Ocean is suggested during late-Neoproterozoic. The detrital records of the early Tonian -Ediacaran strata in the Cathaysia Block present abundant late Mesoproterozoic to early Neoproterozoic(1200-950 Ma)ages. These ages match the record of East Gondwana, and imply a peripheral setting for South China with respect to the supercontinent and most likely adjacent to India during the transitional period from the Rodinia supercontinent to the Gondwana. |
| Key words: Cathaysia Block Neoproterozoic Provenance analysis Rodinia supercontinent Gondwanaland. |
