Abstract: A set of Triassic-Cretaceous terrestrial detrital rocks from 3000 meters to 4000 meters in thickness were developed in the southern edge of Altyn Mountain in the western Qaidam Basin.There are good exposures of Mesozoic strata in the southern edge of Altyn Mountain.A lot of well-preserved paleocurrent structures such as planar cross bedding,trough cross bedding and climbing bedding were developed in the mid-upper Triassic period and mid-lower Jurassic period.These sedimentary structures reveal that the current in the early Mesozoic went along the direction from northeast to southwest in the Yueyashan and went along two directions from southeast to northwest and from northeast to southwest in the Quanyagou.The later might be related to the short-period uplift of Lishiliang.The paleocurrent direction of the Mesozioc era in Lishiliang was considerably irregular.The paleocurrent analysis reveals that there was a large depression in the Mesozoic between Kunlun Orogen and Alabas Fold.

Key words: western Qaidam Basin, Altyn Mountain, Mesozoic, paleocurrent, sedimentary structure

摘要： 柴达木盆地西部(柴西)的阿尔金山南缘自三叠系到白垩系发育了一套陆源碎屑岩,厚度可达3~4km,露头条件非常好.其中,中、上三叠统及中、下侏罗统的陆源碎屑岩中发育了一些指示古流的沉积构造,主要有板状交错层理、槽状交错层理、爬升层理、槽模、炭化植物茎干及砾石.这些沉积构造指示柴西中生代古流格局比较复杂:在月牙山一带,中生代古流自北东流向南西,表明其物源区在北东方向,极有可能是以阿拉巴斯套为主体的古阿尔金山;在犬牙沟与采石岭一带,中生代的古流主要来自于南东方向和北东方向.前者可能与昆仑山和芒崖坳陷腹地的古隆起有关;后者可能与中部的砾石梁一带在中生代某些时期隆升形成“陆桥”而接通了来自北东方向阿拉巴斯套的水系有关.在砾石梁一带,中生代的古流格局则非常紊乱,表明其可能具有多个物源区.在阿拉巴斯套与昆仑山之间中生代发育了一个大的沉积坳陷(古泛芒崖坳陷),这个坳陷呈近东西向,坳陷中心在砾石梁与月牙山南侧一带.

关键词: 柴达木盆地西部, 阿尔金山, 中生界, 古流, 沉积构造