鄂尔多斯地区黄旗口组地球化学特征及其沉积环境与构造背景  

Geochemical Characteristics,Sedimentary Environment and Tectonic Setting of Huangqikou Formation,Ordos Basin

作　　者：宋立军[1,2] 刘池阳[2,3] 赵红格[2,3] 王建强[2,3] 张小龙[2,3] 

机构地区：[1]西安石油大学地球科学与工程学院,陕西西安710065 [2]西北大学大陆动力学国家重点实验室,陕西西安710069 [3]西北大学地质学系,陕西西安710069

出　　处：《地球科学（中国地质大学学报）》2016年第8期1295-1308,1321,共15页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学重点基金项目(No.90814005);国家自然科学基金青年科学基金项目(No.41102072);中国地质调查局项目(No.12120113039900);陕西省自然科学基金项目(No.Z09045);陕西省教育厅基金项目(No.12JK0479);西北大学大陆动力学国家重点实验室联合重点课题项目(No.BJ081334);中国地质大学(武汉)构造地质与油气资源教育部重点实验室基金项目(No.TPR-2012-20);西安石油大学构造地质学精品课程项目

摘　　要：鄂尔多斯盆地西南部及邻区沉积了一套以黄旗口组为代表的巨厚的中元古界碎屑岩系,该套地层具有重要的油气勘探潜力,但目前人们对该套地层的勘探认识尚不够深入,利用碎屑组分、主微量、稀土元素等地球化学手段,结合区域及深部背景特征,探讨了该套地层形成时期的沉积环境和构造背景.结果显示,黄旗口组整体形成于气候干燥的淡水氧化或富氧的过渡环境,沉积期古海水温度较高(平均为32℃);黄旗口组碎屑组分及其主微量元素特征与东非裂谷区相似,加之其沉积于淡水环境,并具有自下段至上段石英砂岩含量逐渐增加的特征,表明研究区黄旗口组应处于陆内裂谷构造背景,自早至晚构造沉积环境日趋稳定,其中早期应为陆内裂谷环境,晚期可能变为坳陷环境,该构造背景的形成可能与华北克拉通逆时针旋转有关.A set of ultra-thick Middle Proterozoic clastic sedimentary rocks deposited in and around southwestern Ordos basin,with the Huangqikou Formation（HKF）as the most typical one,has great potential for oil and gas exploration.However,our understanding of HKF needs to be enhanced.Thus,by means of main-trace,rare elements and detrital component method,we probed into the sedimentary environment and tectonic setting of the HKF.The sedimentary environment discrimination diagrams of both main and trace elements show that the HKF was deposited wholly under a dry environment with fresh water oxidized,or an oxygen-enriched environment,with an average paleoseawater temperature of 32℃.The tectonic environment discrimination diagrams of clastic composition,and main and trace elements all show similarity to those of the East African rift basin,and gradual increasing of the quartz sandstone content from the lower to the upper parts,suggesting that HKF deposited under an intracontinental rift tectonic-sedimentary setting,which may have been caused by the counterclockwise rotation ofNorth China Craton.It is concluded that the HKF was deposited in an intracontinental rift basin in the fresh water,and the tectonic setting became more stable from early to late stage,which was intra-continental rift in the early stage and post-rift depression in the late one.

关 键 词：黄旗口组 地球化学 沉积环境 构造背景 鄂尔多斯盆地 

分 类 号：P534[天文地球—古生物学与地层学]