西藏贡觉盆地古近系贡觉组重矿物分析及地质意义  

Heavy mineral analysis and geological significance of Paleogene Gonjo Formation in Gonjo Basin,Tibet

作　　者：李腾飞 朱志军[1] 丁婷 周世豪 谢林 陈高雨 严锦洁 LI Teng-fei;ZHU Zhi-jun;DING Ting;ZHOU Shi-hao;XIE Lin;CHEN Gao-yu;YAN Jin-jie(School of Geosciences,East China University of Technology,Nanchang 330013,China)

机构地区：[1]东华理工大学地球科学学院,江西南昌330013

出　　处：《岩石矿物学杂志》2022年第5期880-890,共11页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金项目(41362008,U0933605)。

摘　　要：物源分析对研究一个地区的沉积作用、构造演化及储层特征等方面具有重要的意义。为了查明西藏贡觉盆地古近系贡觉组砂岩的物源特征,本文对研究区的重矿物组合特征进行了分析,并结合前人资料揭示了研究区古近系贡觉组砂岩的物源方向,认为油扎、兴达、斑那等地物源方向为自南东向北西,哈家乡物源除有来自于油扎方向外,还有来自于东部逆冲断层上盘的相邻古生界和三叠纪的火成岩单元加入。重矿物组合特征及ATi、GZi等特征指数表明古近系贡觉组物源区成因岩类型较多,但含量不同,以中性火山岩为主,沉积岩较少;根据指相矿物特征判断古近系贡觉组砂岩形成环境为水体较浅的氧化环境,但氧化程度不同,南东部较北西部氧化环境强,斑那村较油扎乡水体浅,氧化度更强。Provenance analysis is of great significance to the study of sedimentation,tectonic evolution and reservoir characteristics in an area.In order to find out the provenance characteristics of the Paleogene Gonjo Formation sandstones in Gonjo Basin,Tibet,this paper analyzes the characteristics of heavy mineral assemblages in the study area,and reveals the provenance direction of the Paleogene Gonjo Formation sandstones in the study area in combination with the previous data.It is believed that the provenance directions of Youzha,Xingda,Banna and other places are from southeast to northwest,and the provenance of Hajiaxiang is not only from the Youzha direction,but also from the adjacent Paleozoic and Triassic igneous rock units in the upper wall of the eastern thrust fault.The characteristics of heavy mineral assemblage and the indexes of ATi and GZi indicate that there are many types of genetic rocks in the provenance area of the Paleogene Gonjo Formation with different contents,mainly intermediate volcanic rocks and less sedimentary rocks.According to the facies mineral characteristics,it is judged that the Paleogene Gonjo Formation sandstone was formed in a shallow-water oxidation environment with different oxidation degree.The oxidation in the southeast is stronger than that in the northwest,the water in Banna is shallower than that in Youzha,and the oxidation degree is stronger.

关 键 词：重矿物 物源 贡觉组 古近系 西藏 

分 类 号：P512.2[天文地球—地质学] P575