琼东南盆地中中新统海底扇碎屑岩锆石U-Pb年龄特征及物源分析  

U-Pb age characteristics of detrital zircon and provenance analysis of a Middle Miocene submarine fan in the Qiongdongnan Basin

作　　者：龚胜利 闫琢玉 李百强 张铜耀 吴土荣 彭俊峰 郑磊 张东峰 黄向胜 罗程飞 王任 GONG Shengli;YAN Zhuoyu;LI Baiqiang;ZHANG Tongyao;WU Turong;PENG Junfeng;ZHENG Lei;ZHANG Dongfeng;HUANG Xiangsheng;LUO Chengfei;WANG Ren(Engineering Technology Company,CNOOC Energy Development Co.,Ltd.,Tianjin 300450,China;Guangdong Province Offshore High Temperature and High Pressure Oil and Gas Reservoir Exploration and Development Enterprise Key Laboratory,Zhanjiang Guangdong 524057,China;Faculty of Earth Science,China University of Geosciences(Wuhan),Wuhan 430074,China;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(Wuhan),Wuhan 430074,China;School of Earth and Environment,Anhui University of Science and Technology,Huainan Anhui 232001,China)

机构地区：[1]中海油能源发展股份有限公司工程技术分公司,天津300450 [2]广东省海上高温高压油气藏勘探开发企业重点实验室,广东湛江524057 [3]中国地质大学(武汉)地球科学学院,武汉430074 [4]中国地质大学(武汉)地质过程与矿产资源国家重点实验室,武汉430074 [5]安徽理工大学地球与环境学院,安徽淮南232001

出　　处：《地质科技通报》2024年第5期45-54,共10页Bulletin of Geological Science and Technology

基　　金：中海石油(中国)有限公司科研项目“琼东南盆地梅山组有效浊积储集体主控因素及储层预测技术”(YXKY-ZX 03 2021);安徽理工大学高层次引进人才科研启动基金项目(2023yjrc81)。

摘　　要：琼东南盆地中中新统海底扇是南海北部天然气勘探的重要目标,但长期以来对该海底扇沉积物的物源并未达成共识,因此,物源分析对于该区天然气勘探有利目标优选具有重要意义。通过钻井取心开展了碎屑锆石U-Pb年龄谱特征研究,并与周缘潜在物源区锆石U-Pb年龄进行了对比分析,示踪了研究区中中新统海底扇物源。结果表明:(1)盆地北部N-1、N-2、N-3、N-4等4口井碎屑锆石U-Pb年龄表现为燕山期(160,157,133,107,102,99 Ma)、印支期(249,241,239 Ma)、加里东期(466,455 Ma)的年龄峰值特征,且与中国海南岛碎屑锆石U-Pb年龄特征相似度高,但与红河、越南中部碎屑锆石U-Pb年龄特征相似度低;(2)盆地南部S-1、S-2、S-3等3口井碎屑锆石U-Pb年龄特征表现为印支期(242,238,237 Ma)、加里东期(435,431,425 Ma)、海西期(396,392 Ma)以及燕山期(143 Ma)的年龄峰值特征,且S-2井具有较年轻的喜马拉雅期(21 Ma)单峰年龄特征。琼东南盆地北部中中新统沉积物源主要来自海南岛,红河及越南中部物源对其影响非常有限,盆地南部中中新统为红河和海南岛双物源供给,且以红河物源为主,自西向东差异明显。[Objective]The middle Miocene submarine fan in the Qiongdongnan Basin is an important target for natural gas exploration in the northern South China Sea.However,there has been no consensus on the source of submarine fan sediments for a long time.Provenance analysis will be important for the optimization of natural gas exploration in this area.[Methods]In this paper,the detrital zircon U-Pb age spectrum characteristics of drilling cores from the middle Miocene submarine fan in the Qiongdongnan Basin were analysed and compared with the U-Pb ages of zircons from potential provenance areas to determine the source of submarine fans in the study area.[Results]The results show that①the U-Pb ages of detrital zircons from the N-1,N-2,N-3 and N-4 wells in the northern part of the basin are characterized by Yanshanian(160,157,133,107,102,99 Ma),Indosinian(249,241,239 Ma)and Caledonian(466,455 Ma)age peaks and have high similarity with the U-Pb age characteristics of detrital zircons from Hainan Island sediments but low similarity with the U-Pb age characteristics of detrital zircons from Red River and central Vietnam sediments.②The detrital zircon U-Pb ages of three wells(S-1,S-2,and S-3)in the southern part of the basin show peak ages of Caledonian(435,431,425 Ma),Hercynian(396,392 Ma),Indosinian(242,238,237 Ma),and Yanshanian(143 Ma).The S-2 well has a younger unimodal Himalayan(21 Ma)age peak.[Conclusion]The provenance of the middle Miocene in the northern part of the basin is Hainan Island.The influence of the provenance on the Red River and Central Vietnam is very limited.The provenance of the middle Miocene in the southern Qiongdongnan Basin was a double-source supply from the Red River and Hainan Island and was dominated by the former,with an obvious difference from west to east.

关 键 词：锆石U-PB年龄 物源 海底扇 中中新统 琼东南盆地 碎屑岩 

分 类 号：P618.51[天文地球—矿床学]