江西省铅山县二叠纪海相火山岩锆石U-Pb年龄及Lu-Hf同位素组成  

Zircon U-Pb age and Lu-Hf isotopic compositions of the Permian marine volcanic rocks in Qianshan County,Jiangxi Province

作　　者：孙建东[1] 骆学全[1] 张雪辉[1] 李胤[2] 吕劲松[1] 康丛轩[1] 骆丁[2] 

机构地区：[1]南京地质矿产研究所,南京210016 [2]江苏省地质调查研究院,南京210018

出　　处：《华东地质》2016年第4期246-251,共6页East China Geology

基　　金：中国地质调查局项目"萍乡-绍兴结合带铜多金属成矿规律研究"(项目编码:12120113065500)和"钦杭成矿带东段重点勘区攻关示范"(项目编码:1212011120846)资助

摘　　要：江西省铅山县中二叠统车头组硅质岩内见夹多层凝灰岩。通过研究该凝灰岩锆石U-Pb年龄及Lu-Hf同位素组成特征,探讨该区海底火山喷流活动的时间、成岩环境及成岩物源。凝灰岩的LA-ICP-MS锆石U-Pb加权平均年龄为264.8±4.4Ma,表明其形成环境为大陆边缘拉张性台盆环境,作为直接地质证据说明这一时期存在海底火山喷发活动。凝灰岩的Lu-Hf同位素二阶段模式年龄为1170~1670Ma（平均值1320 Ma）,为中元古代,代表了成岩物源可能与区域性地壳重熔增生有关。Siliceous rocks of the Middle Permian Chetou Formation in Qianshan County, Jiangxi Province, are found to host several layers of tuff. By studying the zircon U-Pb age and Lu-Hf isotopic compositions of tuff, this paper discussed the time of submarine volcanic eruption, and diagenetic environment and diagenetic provenance. LA-ICP-MS zircon U-Pb weighted average age of tuff is 264.8±4.4Ma, indicating that it formed in the extensional platform-basin environment of continental margin. This can serve as the direct proof to illustrate the occurrence of submarine volcanic eruption during this period. Two-phase Lu-Hf isotopic model age of tuff is 1170-1670 Ma （average 1320 Ma）, suggesting the Proterozoic age and representing that the diagenetic source may be associated with regional crustal remelting hyperplasia.

关 键 词：海相火山岩 锆石U-PB年龄 LU-HF同位素 二叠纪 

分 类 号：P534.46[天文地球—古生物学与地层学] P588.1[天文地球—地质学]