南海白云-荔湾深水区同扩张期岩浆活动特征及构造意义  

Characteristics of Syn-Spread Magmatism and Its Implication for Tectonic Evolution in Baiyun-Liwan Deep-Water Area of Pearl River Mouth Basin

作　　者：朱筱曦 赵中贤[1,2,4] 卓海腾 庞雄 郑金云 孙龙涛 孙珍[1,2,4] Zhu Xiaoxi;Zhao Zhongxian;Zhuo Haiteng;Pang Xiong;Zheng Jinyun;Sun Longtao;Sun Zhen(Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences,Guangzhou 510301,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;University of Chinese Academy of Sciences,Beijing 100049,China;China-Pakistan Joint Research Center on Earth Sciences,Islamabad 45320,Pakistan;School of Marine Sciences,Sun Yat-sen University,Zhuhai 519082,China;CNOOC Deepwater Development Limited,Shenzhen 518054,China)

机构地区：[1]中国科学院边缘海与大洋地质重点实验室,南海海洋研究所,南海生态环境工程创新研究院,广东广州510301 [2]南方海洋科学与工程广东省实验室(广州),广东广州511458 [3]中国科学院大学,北京100049 [4]中国-巴基斯坦地球科学研究中心,伊斯兰堡45320,巴基斯坦 [5]中山大学海洋科学学院,广东珠海519082 [6]中海石油深海开发有限公司,广东深圳518054

出　　处：《地球科学》2023年第10期3781-3798,共18页Earth Science

基　　金：王宽诚教育基金项目(No.GJTD-2018-13);广东省重点领域研发计划项目(No.2020B1111520001);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(Nos.GML2019ZD0104,2019BT02H594,GML2019ZD0205);广东省自然科学基金研究团队项目(No.2017A030312002);广州市科技计划项目(No.201904010285);国家自然科学基金面上项目(No.42076077);中国科学院青年创新促进会项目资助.

摘　　要：南海陆缘深水区发育同裂陷期及同扩张期岩浆,但其时空展布特征、岩浆活动量及活动机制存在较大争议.选取三维反射数据质量较高且覆盖全面的珠江口盆地白云-荔湾深水区,对岩浆活动开展解释和岩浆量的统计工作.在钻井的约束下,综合运用反射特征和接触关系分析以及火山地层学方法,开展了19条高分辨率三维多道反射地震资料解释,在此基础上对白云-荔湾凹陷沉积层中侵入和喷发的岩浆岩开展了系统研究,结果显示:(1)研究区自浅部到深部共识别出100余个火成岩体及与岩浆活动相关构造,含3相11亚相,3相包括火山岩相、侵入相和气液相;(2)岩浆活动划分为33.9~23.0 Ma、23.0~19.1 Ma及19.1~16.0 Ma三个期次,各期岩浆产生量逐期减少;(3)空间上,岩浆活动呈现东南多西北少、由南向北逐渐变新的趋势,且岩浆活动大多分布于周围隆起之上.扩张脊于23.6 Ma时南迁,研究区岩浆活动表现为向北跃迁.推测拉张-扩张早期上涌地幔物质可能受到脊吸作用的影响而导致其上涌头部向洋脊偏转,在扩张脊南迁后,脊吸作用变弱,部分上涌地幔向北回撤,从而导致23 Ma之后岩浆活动向北迁移.扩张结束后岩浆(<17 Ma)碱性程度升高,推测岩浆物质来源变深.The syn-rift and syn-spread magmatism occurs in the deep-water area of the continental margin of the South China Sea in different extents,but it is still controversial regarding its spatial and temporal distribution,the amount,and the mechanism.In this paper,the high-resolution and comprehensive covered three-dimensional(3D)seismic data were used to reveal the characteristics and scale of magmatic activities in the Baiyun-Liwan deep-water area.Under the constraints of drilling,it utilized the seismic reflection characteristics,contact relationship and seismic volcano-stratigraphy comprehensively to interpret 19 highresolution 3D multichannel reflection seismic data.On this basis,the intrusive and eruptive igneous build-ups in the sedimentary layers had been systematically studied.The results show follows:(1)More than 100 igneous bodies and structures related to magmatic activities were identified from shallow to deep in the study area,which are subdivided into 3 seismic facies and 11 subfacies.The 3 facies include volcanic,intrusive and gas-hydro facies.(2)The magmatic activities can be divided into three stages:33.9-23.0 Ma,23.0-19.1 Ma and 19.1-16.0 Ma,and the amount of the magmatic activities gradually decreased.(3)In the spatial distribution,the magmatic activities decrease from the southwest to the northeast,and the ages become younger from the south to the north.Moreover,the magmatic activities are mostly distributed on the surrounding uplift.The magmatism in the study area migrated northward as the spreading ridge jumped southward at 23.6 Ma.It is speculated that the upwelling mantle material in the early stage of rifting-spreading stage may be affected by ridge suction,which caused the upwelling magma to be dragged toward the spreading ridge.After a southward ridge jump,the ridge suction reduced and part if not all of the upwelling mantle retreated northward,resulting in the northward migration of magmatic activities after 23 Ma.The alkalinity of magmatism increased during post-spreading stage(<17 Ma)sugg

关 键 词：南海北缘 白云-荔湾深水区 岩浆活动 时空展布 岩浆量 地球物理 构造 

分 类 号：P376.1[天文地球—地球物理学]