CHANGES OF DETRITAL HEAVY MINERALS’ COMPOSITION IN THE KUQA DEPRESSION FROM CRETACEOUS
Li Shuangjian1, Shi Yonghong2, Wang Qingchen3, Li Zhong3
1. Exploration and Development Research Institute, China Petroleum & Chemical Corp., Beijing 100083; 2. Collage of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009; 3. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029
Detritus sediment is a direct record of mountain uplifting and basin subsidence. The analysis of detritus sediment,including heavy minerals,is necessary means for basin-mountain coupling study.The contents of heavy minerals in the Cretaceous,Paleogene and Neogene from the Kuqa Depression were studied systemically in this paper,and the geochemical compositions of detrital garnets and tourmalines were analysed by electric probe.The results showed that the provenances of the Cretaceous,Paleogene and Neogene in the Kuqa Depression were mainly composed of high-grade metamorphic rocks,sedimentary rocks and intermediate-acid igneous rocks.The composition of garnets in the Cretaceous and Paleogene sandstones was similar with those in low temperature and high pressure metamorphic rocks from the South Tianshan.The garnets from Neogene were rich in almandine,which mainly come from meta-sedimenatry rocks in the South Tianshan.Based on these results,it could be suggested that there might be a large scale uplift and erosion in the South Tianshan from Neogene,which sheltered the contributions of high-pressure metamorphic rocks in the South Tianshan to the Kuqa Depression.