珠一坳陷古近纪物源特征及其沉积演化:来自碎屑锆石年龄的指示  

Provenance Characteristics and Sedimentary Evolution of Zhu I Depression in Paleogene:Indications from Detrital Zircon Ages

作　　者：阙晓铭 舒誉 汪旭东 雷永昌 王宇辰 吴琼玲 Que Xiaoming;Shu Yu;Wang Xudong;Lei Yongchang;Wang Yuchen;Wu Qiongling(Shenzhen Branch of China National Offshore Oil Corporation Limited,Shenzhen 518054,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,广东深圳518054

出　　处：《地球科学》2024年第7期2373-2387,共15页Earth Science

基　　金：国家科技重大专项(No.2016ZX05024-002-008);中海油“十三五”科技重点项目(No.CNOOC-KJ135ZDXM37SZ);中海油“十四五”重大科技项目(No.KJGG-2022-0301)。

摘　　要：珠一坳陷古近系裂陷过程中的沉积演化一直缺乏系统认识.采用碎屑锆石U-Pb定年方法,对珠一坳陷4个凹陷内的钻井古近系文昌组和恩平组砂岩开展“源-汇”对比分析,解析其不同演化阶段年代学、物源特征及沉积演化等信息.结果显示珠一坳陷断陷期不仅接受盆内低凸起区、隆起区剥蚀的碎屑物质,还受到盆外北部古水系长距离搬运的陆源碎屑的影响.其中,始新世文昌组沉积物以盆内短程物源为主,年龄谱系除陆丰凹陷还表现出加里东期-燕山期多峰态外,在各凹陷均以燕山期单峰为特征,洼陷沉积区周缘隆起的中生代岩浆岩、中生界沉积岩地层及新生代火山岩构成该时期湖盆的物质来源;恩平组沉积物在恩平北部和惠州西部率先接受华南水系沉积物影响,在恩平组沉积晚期珠一坳陷普遍接受了来自华南隆褶带的物质输入,年龄谱系呈现以燕山-印支-加里东期为主的多峰特征,出现晋宁期、元古代、新太古代的古老年龄,指示珠一坳陷的物源结构发生重大变化,即由盆内古隆起物源转变为盆内和盆外造山带双重物源,该时期沉积体系以大型浅水三角洲为特征.The sedimentary filling evolution during the Paleogene rifting process in Zhu I depression remains hotly disputed.Tracing source to sink process of the Paleogene was carried out on the sandstones of Wenchang Formation and Enping Formation in Zhu I depression,with the method of zircon U-Pb dating.The geochronology,provenance and sedimentary filling evolution in different evolution stages were further explored.The results show that the sags in Zhu I depression not only received the intrabasinal provenances from the paleo-uplift area,but also were affected by the terrigenous supply transported from the northern peripheral uplifts in South China Block during rifting stage.The Wenchang Formation sediments were dominated by intrabasinal short-distance provenances,which were derived from paleo-uplifts nearby the sags,including Mesozoic magmatic rocks,Mesozoic sedimentary strata and Cenozoic volcanics.The U-Pb geochronology of all sags was characterized by the dominance of Yanshanian clusters except for multi-peaks in Yanshanian,Indosinian,Caledonian periods in Lufeng Sag.The sediments of the Enping Formation were firstly affected by the materials from the South China Block in the north of Enping Sag and the west of Huizhou Sag.During the deposition period of the upper Enping Formation,the age spectra of Zhu I depression sediments show a wide Proterozoic to Mesozoic range with the peak complexity in Yanshanian,Indosinian,Caledonian and Jinningian periods.Thus,the sags were filled by the materials from both the South China Block and peripheral uplifts with the gradual increase of material supply from the South China Block,indicating that the basin provenances had changed from near-source to far-source ones.Meanwhile,the Zhu I depression was characterized by large shallow braided deltas that were formed via relatively long-distance transportation.

关 键 词：碎屑锆石U-Pb 物源转换 珠一坳陷 古近纪 石油地质 

分 类 号：P618.13[天文地球—矿床学]