华夏地块中部震旦系区域对比及其大地构造意义:来自碎屑锆石年代学证据  

Regional Correlation of Sinian Sedimentary of Central Cathaysia Block and Its Tectonic Significance:Evidence from Detrital Zircon Chronology

作　　者：宋芳 牛志军 何垚砚 杨文强 SONG Fang;NIU Zhi-Jun;HE Yao-Yan;YANG Wen-Qiang(Hubei Key Laboratory of Paleontology and Geological Environment Evolution,Wuhan 430205,Hubei,China;Wuhan Center,China Geological Survey(Central South China Innovation Center for Geosciences),Wuhan 430205,Hubei,China)

机构地区：[1]古生物与地质环境演化湖北省重点实验室,湖北武汉430205 [2]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205

出　　处：《华南地质》2024年第2期286-306,共21页South China Geology

基　　金：中国地质调查局地质调查项目(DD20243455、DD20240038、DD20230226、DD20221634);国家自然科学基金项目(U2244212、41772019);古生物与地质环境演化湖北省重点实验室开放基金课题(PEL-202106)。

摘　　要：华夏地块中部震旦纪沉积地层广泛分布,由于岩性较为单一、受后期构造及岩浆作用影响,缺乏顶、底齐全且具有标志层位的剖面,其区域地层对比一直存在争议。本文在粤北和粤东地区对震旦纪沉积地层开展路线剖面调查和碎屑物源研究,结果表明:该地区震旦纪沉积岩是以一套浅变质砂岩、粉砂岩为主,间夹硅质岩的深海-半深海沉积,顶、底以硅质较高的层位为标志;碎屑锆石U-Pb定年结果显示其物源具有~1000 Ma及650~600 Ma两个显著峰值,同时有较为复杂的组成,是典型的“华夏型”物源;根据岩性及碎屑物源特征,华夏地块中部震旦纪沉积地层可以与华夏地块其他地区及华南板块部分区域同时期沉积地层进行对比,指示震旦纪期间华南板块中部不存在宽阔的华南洋,属于统一的沉积盆地。Sinian sedimentary strata widely spread in central Cathaysia Block with unitary lithology and influences of subsequent tectonic-magmatic events,making it very difficult to find complete section with top and bottom in the area.Therefore,the Sinian strata correlation between the Cathaysia and Yangtze blocks has still been controversial.This research focuses on the area of the central Cathaysia Block,northern Guangdong and eastern Guangdong,to conclude the lithology characteristics of late Neoproterozoic strata as a set of abyssal and semi-abyssal deposits dominated by shallow metamorphic sandstone and siltstone interspersed with siliceous rocks,with high silica content on the bottom and top,by geological route survey.The results of U-Pb dating of detrital zircon show that its provenance has two significant peaks of ~1000Ma and ~650Ma,with relatively complex composition,which is a typical "Cathaysia-typed" provenance.Based on the above-mentioned results,the Sinian strata in central Cathaysia Block could be well correlated to that of the other areas of the South China Block,indicating a united sedimentary basin in the central South China without a wide ocean.

关 键 词：震旦系 碎屑锆石LA-ICP-MS U-Pb定年 物源 地层对比 华夏地块 

分 类 号：P542[天文地球—构造地质学] P535[天文地球—地质学]