海南岛雷鸣盆地鹿母湾组碎屑岩地球化学特征、锆石U-Pb年龄和Hf同位素组成:对物源及构造环境的启示  

Geochemical Characteristics,Zircon U-Pb Ages and Hf Isotopic Compositions of the Lumuwan Formation in the Leiming Basin,Hainan Island:Implications for Its Provenance and Tectonic Environment

作　　者：赵朝霞 许德如[1,4] 官军 单强[1,2] 陈根文[1,2] 陈晓清[5] 黄沁怡[1,2,3] 王智琳[6] ZHAO Zhaoxia;XU Deru;GUAN Jun;SHAN Qiang;CHEN Genwen;CHEN Xiaoqing;HUANG Qinyi;WANG Zhilin(CAS Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,Jiangxi,China;Key Laboratory of Marine Geological Resources and Enviroment of Hainan Province,Hainan Geological Survey,Haikou 570206,Hainan,China;Key Laboratory of Metallogenic Prediction of Nonferrous Metalsand Geological Environment Monitoring(Central South University),Ministry of Education,School of Geosciences and Info-Physics,Central South University,Changsha 410083,Hunan,China)

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]中国科学院深地科学卓越创新中心,广东广州510640 [3]中国科学院大学,北京100049 [4]东华理工大学,核资源与环境国家重点实验室,江西南昌330013 [5]海南省地质调查院,海南省海洋地质资源与环境重点实验室,海南海口570206 [6]中南大学地球科学与信息物理学院,有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙410083

出　　处：《大地构造与成矿学》2024年第5期1109-1127,I0003-I0016,共33页Geotectonica et Metallogenia

基　　金：国家自然科学基金重点项目(41930428)资助。

摘　　要：海南岛雷鸣盆地鹿母湾组的确切沉积时限和沉积物来源是研究的空白区域。本文选取雷鸣盆地鹿母湾组作为研究对象,通过全岩地球化学、碎屑锆石U-Pb年代学和Lu-Hf同位素分析,旨在限定其沉积时限及物质来源,并探讨其沉积构造环境。鹿母湾组碎屑沉积岩的最年轻碎屑锆石年龄峰(113.3 Ma)与侵入其中的花岗闪长岩岩体年龄(~107 Ma)限定鹿母湾组沉积时限为109.9~113.3 Ma。全岩地球化学研究表明,鹿母湾组碎屑沉积岩的分异指数(ICV)为0.78~1.52(平均值0.96)、化学风化指数(CIA)为51.11~73.45(平均值65.27),反映其源区岩石具有中等成熟度并经历了弱的化学风化作用。结合微量元素、稀土元素含量及相关比值(如La、Th、Sc、Zr、Hf、∑REE及δEu)、源区判别图和构造环境判别图解,本文认为鹿母湾组碎屑沉积岩可能沉积于活动大陆边缘相关的盆地,主要来源于同时代的长英质火山岩或火山物质,少量碎屑来自华南内陆和海南岛早古生代岩浆岩。Few studies have focused on the age and provenance of the Lumuwan Formation in the Leiming Basin.Here,we present whole-rock geochemistry,zircon U-Pb chronology,and Lu-Hf isotopic compositions of the Lumuwan Formation and discuss the sedimentation time,provenance,and sedimentary tectonic environment.The deposition time of the Lumuwan Formation is 109.9-113.3 Ma constrained by the youngest detrital zircon age peaks(113.3 Ma)and the age of the intruded rock masses(ca.107 Ma).The ICV and CIA of the detrital sedimentary rocks in the Lumuwan Formation range from 0.78 to 1.52 and 51.11 to 73.45,with average values of 0.96 and 65.27,respectively,indicating that the protolith with medium maturity had undergone weak chemical weathering.Combined with the contents and ratios of trace elements(e.g.,La,Th,Sc,Zr,Hf,∑REE andδEu),source discriminant diagrams,and tectonic discriminant diagrams,we conclude that the detrital rocks of the Lumuwan Formation are typical continental-crust-derived sedimentary rocks,which had been likely to be deposited in basins related to active continental margins.This comprehensive study showed that the Lumuwan Formation was mainly sourced from felsic volcanic rocks or volcanic materials contemporaneous with the sedimentation,with a small amount of debris originating from the early Paleozoic magmatic rocks of the South China plate and Hainan Island.

关 键 词：雷鸣盆地 鹿母湾组 地球化学 碎屑锆石U-Pb HF同位素 沉积时限 物源 构造环境 

分 类 号：P597[天文地球—地球化学]