柴达木盆地路乐河组古地理特征及其演化

Paleogeographic Characteristics and Evolution in Lulehe Formation,Qaidam Basin

通过对柴达木盆地盆地钻井岩心的详细分析,在地层划分对比基础上,结合前人研究成果,将盆地古-始新统路乐河组沉积划分为五种沉积相类型,并结合测井相、地震相的识别,对路乐河组沉积特征进行了详细研究。研究表明:该区板块运动控制了盆地的沉积,古近纪初期,由于印度板块与欧亚板块的碰撞俯冲,使柴达木盆地在路乐河组沉积期处于板块挤压阶段,在中生代边缘断陷的基础上周边老山继续隆升,盆地开始下沉,该期成为湖盆的发生、发展时期。由于整个沉积区受到了不同物源供给量以及古气候、古地貌不同,路乐河组沉积期大部分地区主要以红色碎屑沉积为主,大面积发育河流相和洪积相;而由暗色岩系组成的湖泊沉积主要分布在昆仑山和阿尔金山附近,这一带是坳陷湖盆的形成区,相对沉降较快,在狮子沟和七个泉等地发育了深湖相沉积。

Based on detailed analysis of borehole cores and stratigraphic division and correlation in the Qaidam Basin ,combined with previous research findings have partitioned the Paleocene-Eocene Lulehe Formation in the basin into five sedimentary facies types , and combined with well logging facies,seismic facies identification carried out detailed studies on the sedimentary characteristics of Lulehe Formation. The result has shown that the plate movement has controlled sedimentation in the basin. During early Paleogene , the collision and subduction of the Indian plate beneath the Eurasian plate,made Qaidam Basin in plate jams stage during the sedi-mentation of Lulehe Formation. On the basis of Mesozoic marginal fault depression,peripheral old mountains persistently uplifted,ba-sin began to subside,thus the lake basin generating,developing time. Since the whole sedimentary zone had different provenance sup-ply and paleoclimate,paleolandform,most part of the Lulehe Formation are mainly red clastic sediments,large areas of fluvial facies and pluvial facies. While lacustrine sediments comprised of dark rock series are mainly distributed near Kunlun and Altun Mts. ,this district was depressed lake basin formation area with quicker relative settlement,had developed deep lacustrine sediments in Shizigou,Qigequan and other places.