摘要
加蓬盆地盐下储层物源主要来自上地壳,以长英质岩石为主,主要为元古宙汇聚及俯冲构造背景下的变火山-沉积岩组成的古老变质岩系,同时具有一定量碱性玄武岩和花岗岩的混合。盐下Gamba组及Dentale组地层物源碎屑成分及微量元素与源区构造背景继承性好,不同地层差异不明显。主量元素、微量元素及稀土元素特征值分析表明盐下Gamba组及Dentale组物源主要来自具有沟-弧-盆体系的活动大陆边缘的汇聚及俯冲带,具有低SiO_(2)、Na_(2)O的特征,与刚果克拉通西缘元古宙大陆岛弧背景沉积的基麦赞超群、马永贝超群及西刚果超群等变沉积-火山岩系等有亲缘关系。盆地盐下Gamba组及Dentale组储层具有较高的稀土总量,稀土元素配分模式与刚果克拉通元古宙的西刚果造山带的外部带和中间褶皱带具有亲源性,但与南美圣弗朗西斯科克拉通元古宙—太古宙不同构造活动带差异较大,表明它们不是盆地的主要物源,说明盆地盐下Gamba组及Dentale组物源主要来自刚果克拉通。
Provenance of the subsalt reservoir in the Gabon basin mainly comes from the upper crust,mainly felsic rocks,together with the ancient metavolcanic-sedimentary rocks under Proterozoic convergence and subduction tectonic setting.There is certain amount of mixing of alkaline basalt and granite,with good inheritance of provenance composition and tectonic background of the source region,and no obvious difference.Differences in major and trace element compositions in Gamba and Dentale formations are unobvious.Analyses of major elements,trace elements and rare earth elements show that the provenance mainly comes from the convergence and subduction zones of active continental margin,with trench-Arc basin system.They are featured by low SiO_(2) and Na_(2)O,similar to the Katanga supergroup and Pore group deposited in Proterozoic back-Arc basin on the western margin of Congo Craton.The Delonggu group is related to each other.The sub-salt reservoirs in the basin have high total REE content.The REE distribution pattern is related to the Proterozoic Lufili orogenic belt on the western margin of Congo Craton,but differs greatly from the Proterozoic Archean tectonic belts of San Francisco Craton in South America.This indicates that they are not the main provenance of the basin,and that the provenance is mainly the Congo Craton.
作者
陈全红
阳怀忠
赵红岩
张科
黄海滨
郭家铭
刘新颖
袁野
CHEN Quanhong;YANG Huaizhong;ZHAO Hongyan;ZHANG Ke;HUANG Haibin;GUO Jiaming;LIU Xinying;YUAN Ye(Research Institute of Exploration&Development Technology,CNOOC International Ltd.,Beijing 100028,China;Offshore Oil Engineering Co.,Ltd.,Tianjin 300451,China)
出处
《现代地质》
CAS
CSCD
北大核心
2023年第5期1385-1397,共13页
Geoscience
基金
中海油“十四五”重大科技项目“两岸一带重点区油气勘探评价关键技术”(KJGG2022-0902)。
