东海盆地西湖凹陷中西部花港组物源方向判别与源区性质分析  

Provenance indication and source characteristics of Huagang Formation in the central and western Xihu sag of the East China Sea basin

作　　者：王文义 程宏岗[3] 徐淑娟[3] 林琦 黄瑀 董欣怡 李德勇[1,2] WANG Wenyi;CHENG Honggang;XU Shujuan;LIN Qi;HUANG Yu;DONG Xinyi;LI Deyong(College of Marine Geosciences,Ocean University of China,Qingdao,Shandong 266100,China;Key Laboratory of Submarine Geosciences and Prospecting Techniques,MOE,Qingdao,Shandong 266100,China;Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China;Qingdao Institute of Marine Geology,China Geological Survey,Qingdao,Shandong 266237,China;Nanyang Institute of Technology,Nanyang,Henan 473004,China)

机构地区：[1]中国海洋大学海洋地球科学学院,山东青岛266100 [2]海底科学与探测技术教育部重点实验室,山东青岛266100 [3]中国石油勘探开发研究院,北京100083 [4]中国地质调查局青岛海洋地质研究所,山东青岛266237 [5]南阳理工学院,河南南阳473004

出　　处：《中国海上油气》2023年第2期33-43,共11页China Offshore Oil and Gas

基　　金：国家自然科学青年基金项目“冲绳海槽中南段陆坡海底峡谷侵蚀-沉积结构与形成演化机制(编号:41806073)”;山东省自然科学基金项目“东海丽水凹陷晚古新世层序构成样式及对海平面变化和构造地貌演化的响应(编号:ZR2017BD014)”;海底科学与探测技术教育部重点实验室基金项目“冲绳海槽陆坡海底峡谷侵蚀沉积演化及对水合物动态成藏的制约(编号:SGPT-2020OF-06)”部分研究成果。

摘　　要：西湖凹陷中西部花港组的物源方向及源区性质是研究区沉积体系划分及有利油气相带预测的重要依据。通过收集研究区14口井共计300余块岩石样品,利用重矿物和稀土元素两种物源分析方法,对东海盆地西湖凹陷中西部花港组进行物源方向和源区性质分析。结果表明:①西湖凹陷重矿物种类多,不同样品重矿物组合差异大,指示出源区性质较为复杂。②稀土元素总量较高,轻重稀土元素分异明显,轻稀土富集。铕元素负异常显示西湖凹陷源岩主要为酸性花岗岩。铈元素微负异常显示花港组沉积时水体介质为缺氧的还原环境。不同地区稀土元素的配分模式具有一定差异性,进一步表明源区性质的复杂性,源岩以花岗岩为主,凹陷北部和平湖斜坡带存在变质岩的混源。其构造背景接近大陆边缘构造,元古代变质基底导致西湖凹陷母岩古老沉积物成分增加,局部发育元古代变质岩。③花港组物源来自NW向的海礁隆起和W向的渔山隆起,具体为北部物源来自海礁隆起北块的燕山期火成岩与前震旦纪变质岩,南部物源为海礁隆起南块和渔山隆起的综合作用。利用R型因子分析方法,以构造的物源指示因子F1更加精细的判别了物源方向,将南支物源进行了细分,3个分支分别南部来自渔山隆起的中生代花岗岩,中南部来自海礁隆起南块的燕山期火成岩与元古代变质岩。The provenance direction and source characteristics of the Huagang Formation in the central and western Xihu sag are important bases for the division of sedimentary systems and the prediction of favorable oil and gas facies zones in the study area.By collecting more than 300 rock samples from 14 wells in the study area and using two provenance analysis methods of heavy minerals and rare earth elements,the provenance direction and source characteristics of the Huagang Formation in the central and western Xihu sag of the East China Sea basin were analyzed.The result indicated that:①There are many types of heavy minerals in Xihu sag,and the heavy mineral assemblages of different samples vary greatly,indicating that the source characteristics are relatively complex.②The total amount of rare earth elements is relatively high,the light and heavy rare earth elements are significantly differentiated,and the light rare earth elements are enriched.The negative anomaly of europium element indicates that the source rock of Xihu sag is mainly acidic granite.The slight negative anomaly of cerium element indicates that the water medium during the deposition of the Huagang Formation was an anoxic reducing environment.The distribution patterns of rare earth elements in different regions have certain differences,further indicating the complexity of the source characteristics.The source rock is mainly granite,and there are mixed sources of metamorphic rocks in the northern Xihu sag and Pinghu slope zone.The tectonic setting is close to the continental margin structure,and the Proterozoic metamorphic basement resulted in an increase in the composition of ancient sediments of the parent rock in the Xihu sag,with the development of Proterozoic metamorphic rocks locally.③The provenance of the Huagang Formation comes from the Haijiao uplift in the NW direction and the Yushan uplift in the W direction.Specifically,the northern provenance comes from the Yanshanian igneous rocks and pre-Sinian metamorphic rocks in the northern block

关 键 词：物源分析 重矿物 稀土元素 西湖凹陷 花港组 

分 类 号：TE121.3[石油与天然气工程—油气勘探]