海南岛西部近岸海域碎屑锆石U-Pb同位素年代学物源示踪及其地质意义  

Detrital Zircon U-Pb Geochronology from Coastal Sea of Western Hainan Island: Provenance Tracing and Geological Implications

作　　者：曾广骅 陈旸 许国强 梁定勇 ZENG Guang-hua;CHEN Yang;XU Guo-qiang;LIANG Ding-yong(Hainan Key Laboratory of Marine GeologicalResources and Environment,Haikou 570206,China;Hainan Geological Survey,Haikou 570206,China;Marine Geological Survey of Hainan Province,Haikou 570206,China;Sanya Exploration Institute of Hydrogeology and Engineering Geology,Sanya 572000,China)

机构地区：[1]海南省海洋地质资源与环境重点实验室,海口570206 [2]海南省地质调查院,海口570206 [3]海南省海洋地质调查院,海口570206 [4]三亚水文地质工程地质勘察院,三亚572000

出　　处：《科学技术与工程》2024年第16期6626-6641,共16页Science Technology and Engineering

基　　金：海南省海洋地质资源与环境重点实验室自主课题基金(HNHYDZZYHJZZ002,22-HNHYDZZYHJZZ006);海南省自然科学基金(421RC754)。

摘　　要：海南岛西部近岸海域海砂资源丰富、经济价值巨大,对其物质来源却缺乏系统研究。为解决这一科学问题,为该区域海砂资源的开发利用提供科学依据,对海南岛西部近岸海域和昌化江入海口1 471粒碎屑锆石开展了U-Pb同位素年代学和微区元素地球化学研究。海南岛西部近岸海域年龄范围在3.45 Ga~82 Ma,具有99、241、252 Ma 3个主要年龄峰值,以及113、155、325、357 Ma 4个次要年龄峰值;昌化江入海口具有2.3 Ga~96 Ma的年龄范围,存在101、244、254 Ma 3个主要年龄峰值,以及122、266、281、307、342 Ma 4个次要年龄峰值。结果表明:海南岛西部近岸海域沉积物以具有~99 Ma的显著年龄峰,并缺乏晋宁期、加里东期和喜山期年龄峰为识别标志,海南岛应是其主要物源区,区内丰富的海砂资源来源于海南岛内岩浆岩和沉积岩的风化剥蚀和搬运沉积;海南岛西部近岸海域与昌化江沉积物年龄峰值的差异,指示海南岛西部近岸海域沉积物并非单纯来源于近源昌化江输入,也在北部湾逆时针环流的作用下接受琼西南部河流的物源贡献;更新昌化江入海口的碎屑锆石年龄组成,新识别出的380~310 Ma年龄群,可作为昌化江流域物源的识别标志;本次碎屑锆石年龄频谱特征与海南岛经历的多次重要地质事件相吻合,有助于了解海南岛复杂的地质演化历史。The sea sand in the shallow sea around the estuary of Changhua River are rich in resources and of great economic value,but there is no systematic research on their provenance.To solve this scientific problem,U-Pb isotope geochronology and in suit element geochemistry of 1471 grains of detrital zircons from the coastal sea of western Hainan Island and the estuary of the Changhua River were investigated.The age range of the coastal sea of western Hainan Island is 3.45 Ga~82 Ma,with three major age peaks of 99,241,252 Ma,and four minor age peaks of 113,155,325,357 Ma,The age range of the estuary of Changhua River is 2.3 Ga~96 Ma,with three major age peaks of 101,244,254 Ma,and four minor age peaks of 122,266,281,307,342 Ma.The results show that the sediments in the coastal sea of western Hainan Island are identified by the significant age peak of~99 Ma and the lack of age peaks of Jinninian,Caledonian and Himalayan,and Hainan Island should be its main source area.The difference between the age peaks of the coastal sea of western Hainan Island and the estuary of Changhua River indicates the source contribution from the rivers in the south side of western Hainan Island.The newly identified 380~310 Ma age group can be used as a source identification marker in the Changhua River Basin.This detrital zircon age spectrum is consistent with several important geological events in Hainan Island,which contributes to the understanding of the complex geological evolution history of Hainan Island.

关 键 词：海南岛西部海域 海砂 碎屑锆石U-Pb同位素年代学 物源示踪 构造演化 

分 类 号：P67[天文地球—海洋地质]