| 南海北部阳江?一统暗沙断裂带与新近纪岩浆活动 |
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| 引用本文： | 蔡国富,张向涛,彭光荣,吴静,柳保军,白海军,李振升,马晓楠,李三忠,索艳慧.南海北部阳江?一统暗沙断裂带与新近纪岩浆活动[J].大地构造与成矿学,2021,45(1):40-52. |
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| 作者姓名： | 蔡国富 张向涛 彭光荣 吴静 柳保军 白海军 李振升 马晓楠 李三忠 索艳慧 |
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| 作者单位： | 中海石油(中国)有限公司 深圳分公司,广东 深圳 518000;深海圈层与地球系统教育部前沿科学中心,海底科学与探测技术教育部重点实验室,中国海洋大学 海洋地球科学学院,山东 青岛 266100;青岛海洋科学与技术国家实验室 海洋矿产资源评价与探测技术功能实验室,山东 青岛 266100 |
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| 基金项目： | 中海石油(中国)有限公司深圳分公司科研项目;"十三五"国家科技重大专项 |
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| 摘 要： | 阳江-一统暗沙断裂带是南海北部珠江口盆地极其重要的中-新生代构造带和转换带。基于钻井资料和大范围、高密度的二维、三维地震资料,本文初步揭示阳江-一统暗沙断裂带走向为NW-NWW向、宽约30km,沿着断裂走向从陆架至洋陆边界断裂带可分为北-中-南三段,断裂在新生代选择性活化,具有多重走滑断裂叠合和基底岩浆底辟强烈等特点,表明其在新生代构造调节作用中发展成一个活动断裂带。通过对断裂带及其围区新近纪岩浆活动的系统解析,首次揭示了新近纪岩浆沿该深大断裂在大陆架-深水大陆坡均有强烈活动,具有沿断裂带走向呈带状分布、南早北晚和多期次幕式迁移等特征。新近纪岩浆活动开始于23.0 Ma,在断裂带南段的云开低凸起及邻区形成强烈的基底岩浆底辟。岩浆喷发作用集中在21.1~19.1 Ma、18.5 Ma、15.5~13.5 Ma和8~6 Ma等4个时期。在21.1~19.1 Ma期间,岩浆活动迁移到中段的开平东洼和神狐隆起东缘之间,出现了强烈的火山裂隙式喷发。18.5 Ma以来,断裂带南段-中段火山喷发作用基本停止,岩浆活动向北迁移到北段的阳江东凹一带,具有中心式溢流相喷发叠合裂隙式火山喷发的特征。推测阳江-一统暗沙断裂带新近纪的岩浆来源于南海北部地幔上涌区的下地壳高速体减压熔融,而断裂带上岩浆活动表现出的时空不均一性和幕式迁移性,可能与地幔上涌区向海倾斜特性及断裂带分段差异活动有关。
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| 关 键 词： | 南海北部 阳江—一统暗沙断裂带 岩浆活动 地幔上涌 新近纪 洋陆过渡带 |
Neogene Volcanism and Tectonics along the Yangjing-Yitong'ansha Fault Zone in the Northern South China Sea Margin |
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| CAI Guofu,ZHANG Xiangtao,PENG Guangrong,WU Jing,LIU Baojun,BAI Haijun,LI Zhensheng,MA Xiaonan,LI Sanzhong,SUO Yanhui.Neogene Volcanism and Tectonics along the Yangjing-Yitong'ansha Fault Zone in the Northern South China Sea Margin[J].Geotectonica et Metallogenia,2021,45(1):40-52. |
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| Authors: | CAI Guofu ZHANG Xiangtao PENG Guangrong WU Jing LIU Baojun BAI Haijun LI Zhensheng MA Xiaonan LI Sanzhong SUO Yanhui |
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| Institution: | (Shenzhen Branch,CNOOC China Limited,Shenzhen 518000,Guangdong,China;Frontiers Science Center for Deep Ocean Multispheres and Earth System,Key Lab of Submarine Geosciences and Prospecting Techniques,MOE and College of Marine Geosciences,Ocean University of China,Qingdao 266100,Shandong,China;Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266100,Shandong,China) |
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| Abstract: | The Yangjiang-Yitong’ansha Blind Fault Zone(YJBFZ)is an important Meso-Cenozoic structural belt and transition zone in the Pearl River Mouth Basin in the northern South China Sea.Based on drilling and large-scale,high-density 2D and 3D seismic data,this paper firstly reveals that the YJBFZ is NW-NWW-trending,about 30 km in width,and can be divided into northern,middle and southern segments from the continental shelf to the ocean-continent boundary.Being a fault transfer or accommodation zone,the YJBFZ was selectively activated in Cenozoic Era characterized by multiple-stage superimposition of strike slip faults and strong basement magma intrusion.The Neogene magmatism along the fault zone was observed for the first time to occur on the continental shelf and deep-water continental slope,moreover,the temporal and spatial heterogeneity has been recognized for the episodic magmatic activity.The Neogene magmatic activity along the fault zone can be divided into four periods:21.1–19.1 Ma,18.5 Ma,15.5–13.5 Ma and 8–6 Ma are the most intensive,and characterized by NW-NWW zonation and multi-stage activity,early in the south and late in the north.The Neogene magmatism began at 23.0 Ma,formed strong magma underplating in the Yunkai Lower Heave and its adjacent areas in the ocean-continent transitional zone.During the period of 21.1–19.1 Ma,the magmatic activity migrated to the middle of the eastern Kaiping Sag and the eastern Shenhu Uplift,resulted in a strong volcanic fissure eruption.Since 18.5 Ma,the volcanic eruption in the southern and middle segments of the fault zone has basically stopped,whereas the activity migrated northwardly to the eastern Yangjiang Sag in the north segment roughly consistent with the NWW strike of the fault.The young volcanic system is characterized by the central overflow facies of eruptive rocks and peripheral fissure volcanism of extrusive rocks.The Neogene magma in the YJBFZ is supposed to be derived from decompression melting of the high velocity layer of the lower crust,caused by mantle upwelling plume beneath the northern South China Sea Margin.The temporal and spatial heterogeneity of the magmatic activity along the fault zone may be related to the tilting mantle upwelling plume from continental shelf to the slope and the differential activity of the fault zone. |
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| Keywords: | northern South China Sea Yangjiang-Yitong’ansha Blind Fault Zone magmatism mantle upwelling Neogene ocean-continent transfer zone |
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