Detection of a mud volcano in the Weitan Banks area of the northern South China Sea  

作　　者：Wei LUO Pin YAN Yanlin WANG Junhui YU Qionghua WAN Zhenbo ZHANG Tao XUE 

机构地区：[1]Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China [2]Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China [3]CNOOC International Energy Services(Beijing)Co.,Ltd.,Beijing 100028,China [4]University of Chinese Academy of Sciences,Beijing 100049,China [5]Oilfield Engineering Research Institute of Geophysics,CNOOC Energy Technology and Services,Zhanjiang 524057,China

出　　处：《Journal of Oceanology and Limnology》2024年第5期1450-1469,共20页海洋湖沼学报（英文）

基　　金：Supported by the Special Supporting Program for Cultivating High level Talents in Guangdong Province(No.2019 BT02H594);the National Natural Science Foundation of China(NSFC)(Nos.U1901217,91855101,42306239);the Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515011836,2021 A 1515110851);The sub bottom profiling,multi-beam sounding data and benthal samples were collected onboard R/Vs Jiageng and Dongfanghong-3 implementing the open research cruises(Nos.NORC 2017-05,NORC 2017-06,NORC 2018-06,NORC 2019-05,NORC 2019-06,NORC 2020-05,NORC 2020-06);NSFC Shiptime Sharing Project(Nos.41649905,41649906,41749906,41949905,41949906,41949905,41949906)。

摘　　要：Situated between the petroliferous Cenozoic Zhujiang(Pearl)River Mouth Basin and the mud volcano-rich Mesozoic Dongsha Basin in the middle sector of the northern South China Sea,the Weitan Banks area has been previously mapped as a basement high that is composed of Mesozoic magmatic rocks.In this study,we present several favorable indicators for petroleum geology that were detected from geophysical profiling and benthic sampling in the area.A conspicuous hill was discovered,named“Zhongwei Hill”,~80 m high above the~340 m deep seafloor and~1 km broad,in a depression with more than 7 km thick sedimentary strata.The Zhongwei Hill was seismically imaged with a mushroom-shaped structure and containing a cake-like crown,fluid flow pipes,and an~10 km broad anticline at depth.Thus,the hill represents a source-plumbing-eruption system.Shallow gas zones linked to deep fracture were found at or near the hill.Stratigraphic correlation indicates that the deep strata comprise the Jurassic and Paleogene strata,the major hosts of hydrocarbon source rocks.In addition to the hill,there are number of mounds from which three bottom water samples were collected and the samples are rich in dissolved methane with concentrations high up to~900 nmol/L,much higher than the background level(0.5–2 nmol/L).The benthic samples are rich in coarse sediment clastics,authigenic carbonate nodules,and deep-water habitats likely feeding on methanotrophic community.Given these observations and the context,we propose that the Zhongwei Hill represents a mud volcano,likely thermally driven,that seeps methane from Jurassic and Paleogene source layers,thus poses a favorable clue for significant hydrocarbon generation capacity in transitional zone of the Zhujiang River Mouth Basin and the Dongsha Basin.

关 键 词：South China Sea Zhongwei Hill deep-level anticline mud volcano Mesozoic source layer hydrocarbon generation 

分 类 号：P714[天文地球—海洋科学]