藏北可可西里盆地老第三纪沉积物源区分析及其高原隆升意义

可可西里盆地位于昆仑山和唐古拉山之间 ,是青藏高原腹地最大的第三纪沉积盆地 ,对于研究青藏高原早期隆升和地壳短缩过程具有重要作用 .盆地保存的始新世—渐新世早期风火山群和雅西措群主要由碎屑岩和泥岩组成 ,厚度为 5 45 2 .8m .碎屑岩的物源区分析表明 ,风火山群主要来自于南部的唐古拉造山带二叠—三叠纪地层 ,而雅西措群主要来自于南部的唐古拉、白日榨加和黑石山 -高山造山带 ,剥蚀深度加大至石炭—二叠纪地层 .它们的沉积演化过程是盆地南部造山带老第三纪构造隆升持续加强的结果 ,表明在雅西措群沉积时期青藏高原北部已经隆升至一定的高度 .

PROVENANCE OF PALEOGENE SEDIMENTS IN HOH XIL BASIN, NORTH OF QINGZANG PLATEAU, AND ITS SIGNIFICANCE FOR PLATEAU UPLIFT

The Hoh Xil basin, the largest Tertiary sedimentary basin in the hinterland of the Qingzang plateau between the Kunlun Mountain and the Tanggula Mountain, may be significant for the research into the early uplift and the crustal shortening of the plateau. The 5 452.8 m-thick Eocene-Early Oligocene Fenghuoshan and Yaxicuo groups preserved in the basin consist mainly of clastic rocks and mudstone. The analysis of the clastic-rock provenance shows that the Fenghuoshan Group originated mainly from the Permian-Triassic strata in the Tanggula orogenic zone in the south, and that the Yaxicuo Group originated mainly from the Carboniferous-Permian strata in the Tanggula, Bairizhajia, and Heishishan-Gaoshan orogenic zones in the south. These sedimentary evolutionary process results from the persistent strengthening of the Paleogene tectonic uplift of the orogenic zone in the southern Hoh Xil basin, indicating that the north of the Qingzang plateau had already been uplifted to a certain height in the sedimentary period of the Yaxicuo Group.