赣南南华纪变质沉凝灰岩的碎屑锆石U-Pb年代学及其对裂谷盆地形成时间的限定  

Detrital zircon U-Pb dating of Nanhua meta-tuffite in South Jiangxi and constraint on the time limit of the rift basin

作　　者：赵芝[1] 臧雯蕊 王臻 陈振宇[1] 陈斌锋[3] 邹新勇 ZHAO Zhi;ZANGWenrui;WANG Zhen;CHEN Zhenyu;CHEN Bingfeng;ZOU Xinyong(MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Geological Survey Team of Gannan,Bureau of Geology and Mineral Exploration&Development of Jiangxi Province,Ganzhou 341000,Jiangxi,China)

机构地区：[1]自然资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,北京100037 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]江西省地质矿产勘查开发局赣南地质调查大队,江西赣州341000

出　　处：《中国地质》2021年第2期564-579,共16页Geology in China

基　　金：中央级公益性科研院所基本科研业务费专项基金(K1506和YYWF201527)资助。

摘　　要：江西省宁都某地新元古代浅变质岩风化壳中赋存离子吸附型稀土矿,文章对某矿区内原定青白口纪库里组的2件变质沉凝灰岩样品进行了碎屑锆石LA-ICP-MS U-Pb年代学研究,获得了88组和110组谐和年龄。2件样品的碎屑锆石年龄区间相似,主要分布在:810~780 Ma,峰值年龄为798 Ma(n=55);748~727 Ma,峰值年龄为737 Ma(n=127);691~667 Ma,峰值年龄为680 Ma(n=6),此外还有少量的年龄分布在2.85~1.08 Ga。认为,变质沉凝灰岩样品的沉积时代可能为南华纪,地层应归属为上施组;物源可能来自江南造山带东段(赣东北—皖南—浙西)青白口纪晚期—南华纪的火山-沉积岩;赣南区域上同时期的巨厚海相火山-碎屑沉积可能形成于华南古大陆裂解之后的裂谷盆地,赣南次级裂谷盆地的沉积时限为810~727 Ma。Ion-adsorption type REE deposits is hosted in regolith of Neoproterozoic epimetamorphic rocks in South Jiangxi,China.LA-ICP-MS U-Pb dating of detrital zircons from two metamorphic tuff samples of the originally identified Kuli Formation of Qingbaikou System in a mine area yielded the harmonic ages of 88 groups and 110 groups respectively.They are predominantly Neoproterozoic and have ages ranging from 810 to 667 Ma with three age peaks at ca 798 Ma(n=55),737 Ma(n=127)and 680 Ma(n=6).There are also a few Meso-to Paleoproterozoic zircon grains with ages scattering from 2.85 Ga to 1.08 Ga.The dating results probably suggest that the sedimentary age of the tuffite may be Nanhua Period.It is speculated that the provenance may be volcanic-sedimentary rocks of late Qingbaikou Period to Nanhua Period in the eastern part of Jiangnan orogenic belt(northeast Jiangxi-southern Anhui-western Zhejiang).The super thick marine volcanic-clastic sediments of the same period in southern Jiangxi might be formed in the rift basin after the breakup of the ancient continent of South China,and the sedimentary time of the secondary rift basin in southern Jiangxi is about 810-727 Ma.

关 键 词：南华纪 变质沉凝灰岩 碎屑锆石U-Pb定年 裂谷盆地 地质调查工程 赣南 

分 类 号：P578.496[天文地球—矿物学] P597.3[天文地球—地质学]