渤海湾盆地临南洼陷沙三段辉绿岩地球化学特征及其构造意义  

Geochemical characteristics and tectonic significance of diabase of Es_(3) Member in Linnan Subsag,Bohai Bay Basin

作　　者：李元哲 边伟华[1,2] 赵兰全 季金礁 柏佳伟 陆国超 LI Yuanzhe;BIAN Weihua;ZHAO Lanquan;JI Jinjiao;BAI Jiawei;LU Guochao(College of Earth Sciences,Jilin University,Changchun 130061,China;Key Laboratory of Mineral Resources Evaluation in Northeast Asia,Ministry of Natural Resources,Jilin University,Changchun 130061,China;Exploration and Development Institute,Sinopec Shengli Oilfield Company,Dongying 257009,Shandong,China)

机构地区：[1]吉林大学地球科学学院,长春130061 [2]自然资源部东北亚矿产资源评价重点实验室(吉林大学),长春130061 [3]中石化胜利油田勘探开发研究院,山东东营257099

出　　处：《世界地质》2024年第2期204-215,共12页World Geology

基　　金：国家自然科学基金项目(41790453)。

摘　　要：辉绿岩作为一种重要的非常规油气储集单元,其形成和分布通常受控于大地构造背景。笔者以渤海湾盆地临南洼陷沙三段辉绿岩为研究对象,采用岩石学、地球化学和Sr-Nd同位素地球化学等方法,探讨辉绿岩地球化学特征及其地球动力学背景。研究结果表明,辉绿岩属于富钠碱性玄武岩系列,高铝低钛,大离子亲石元素(Rb、Ba、Pb、Sr)和轻稀土元素富集,高场强元素(Th、U)相对亏损,显示Eu正异常。研究区辉绿岩源于不同壳幔端元相互混合的软流圈地幔。辉绿岩的形成与板内岩浆活动有关,且岩浆侵位过程中发生与地壳物质的混染,是大陆伸展构造背景下的产物。渤海湾盆地新生代伸展属于主动裂谷环境,软流圈地幔上涌与太平洋板块向欧亚板块俯冲和板内地幔柱的形成密切相关。As an important unconventional oil and gas reservoir unit,the formation and distribution of diabase are often controlled by their tectonic settings.Using petrology,geochemistry,and Sr--Nd isotopes geochemistry,the authors discuss the geochemical characteristics and geodynamic background of diabase of Es_(3) Member in Linnan Subsag,Bohai Bay Basin.The results show that the diabase belongs to the series of alkaline basalts with high Al,low Ti and enriched Na.The large ion lithophile elements(Rb,Ba,Pb,Sr)and light rare earth elements are relatively enriched,while the high field strength elements(Th,U)are relatively depleted,exhibiting a positive Eu anomaly.The diabase in the study area originates from the asthenosphere mantle,which is the result of mixing between different crust-mantle boundary zones.The formation of diabase is associated with intraplate magmatic activities,which suffered contamination by crustal materials during magma emplacement,occurring under a continental extensional tectonic setting.The Cenozoic extension in the Bohai Bay Basin occurred under an active rift environment,where the upwelling of the asthenosphere mantle was closely associated with the subduction of the Pacific Plate beneath the Eurasian Plate and the development of an intraplate mantle plume.

关 键 词：辉绿岩 地球化学特征 SR-ND同位素 主动裂谷 临南洼陷 渤海湾盆地 

分 类 号：P597[天文地球—地球化学]