【摘要】 柴达木中生界盆地形成时间及其盆地原型研究存在很大争议,主要原因在于对盆地内有无三叠系陆相沉积及其与上覆下侏罗统地层接触关系和中生界原型盆地形成的构造背景等问题认识不清。区域地质调查在盆地西部月牙山北发现中、上三叠统陆相地层与上覆下侏罗统地层整合接触,在此基础上,结合地表露头、古流分析及地震解释资料研究认为:柴达木中生界盆地起始于中三叠世。中生代在古阿拉巴斯套山与古昆仑山间发育一个大的近东西向展布的活动型山间盆地,盆地经历了中—晚三叠世、早—中侏罗世和晚侏罗世—白垩纪三个演化阶段,分别对应发育了中—晚三叠世坳陷型盆地、早—中侏罗世断陷型盆地和晚侏罗世—白垩纪坳陷型盆地三种原型盆地类型。中—晚三叠世盆地分布比较局限,沉积以氧化环境下的红色碎屑岩建造为主,不具生烃能力;早—中侏罗世盆地范围扩大,沉积物以暗色含煤建造为主,主要分布于现今的阿尔金山地区及其山前地带,沉积中心在阿尔金山地区。晚侏罗世—白垩纪阿尔金山快速隆升,成为主要物源区,开始分割塔里木和柴达木盆地沉积,沉积物为红色磨拉石建造。该研究对于准确评价柴达木盆地生烃潜力及合理进行勘探部署具有重要意义。更多还原

【Abstract】 Based on an investigation of Mesozoic outcrops as well as paleocurrent and seismic interpretation data,the authors studied the prototypes and evolution of the Mesozoic Qaidam basin.The results show that the Mesozoic Qaidam basin started with Middle Triassic small intermontane depressions.There also developed an intermontane basin between the old Alabasitao Mountain and the Kunlun Mountains in Mesozoic,trending in E-W direction.The basin underwent three tectonic evolution stages,i.e.,Middle-Late Triassic,Early-Middle Jurassic and Late Jurassic-Cretaceous,corresponding to the development of three prototype basins.The Middle-Late Triassic basin was of the depression type,the Early-Middle Jurassic basin was of the fault basin type,and the Late Jurassic-Cretaceous basin was of the depression type.The Middle-Late Triassic depression was restricted in the Yueyashanbei region,and the sediments were red clastic rocks which deposited under an oxidizing environment with no hydrocarbon-generating potential.The Early-Middle Jurassic fault type basin was characterized by the coal-bearing formation,which was widespread in the present Altun Mountains and the neighboring areas in the Qaidam basin.The depocenter was in the present Altun Mountain area.During Late Jurassic-Cretaceous,the Altyn Mountainsa-Qingshuigou cross section;b-Meigou cross section;c-Quanyagou cross section;d-Quan nan 1 cross section;e-Caishiling cross section;f-Heishishan cross section;g-Sanjiaojia cross section;h-Yueyashanbei cross section;i-Meiyaogou cross section;1-Proterozoic;2-granite;3-Ordovician;4-Triassic;5-Upper Jurassic;6-Lower-Middle Jurassic;7-Cretaceous;8-Cenozoic;9-location of cross section;10-study area;11-location of well uplifted rapidly and,as the major provenance,began to separate the Tarim basin from the Qaidam basin.The Late Jurassic-Cretaceous sediments were coarse clastic formations.This study is of significance in the exact evaluation of hydrocarbon potential and the rational arrangement of the exploration work in the Qaidam basin.更多还原