柴达木盆地西部新近纪岩相古地理研究

Neogene sedimentary facies and palaeogeography of western Qaidam Basin, Qinghai

关键词:  柴西  新近纪  岩相古地理

Key words:  western Qaidam Basin  Neogene  sedimentary facies and palaeogeography

摘要:

通过对研究区新近系露头及钻井剖面的岩性、结构构造、古生物的综合分析,将柴西地区新近系沉积相划分为5种相和亚相:扇三角洲、河流-泛滥平原、滨湖、浅湖、半深湖。沉积相的空间展布大体以茫崖和大风山为沉积中心,到盆地边缘依次发育半深湖相、浅湖相、滨湖相,并呈环带状分布。扇三角洲相和河流泛滥平原相发育于昆仑山和阿尔金山前。古地形为西高东低,南高北低,物源来自阿尔金山和昆仑山,气候炎热干旱。下油砂山组为较好的烃源岩,储层主要为孔隙性碎屑岩储层和裂缝性非常规储层两种。

Abstract:

In the light of lithology, sedimentary structures and textures and palaeontology, the Neogene sedimentary facies in western Qaidam Basin, Qinghai consist of fan delta, fluvial-flood plain, littoral lake, shallow lake and bathyal lake facies. From the central Mangnai and Dafengshan to the basin margins, there develop the bathyal lake, shallow lake and littoral lake facies. The fan delta and fluvial-flood plain facies appear in the foreland of the Kunlun and Altun Mountains. The palaeotopography displayed the patterns of being higher in the western and southern parts and lower in the eastern and northern parts of the Basin. The palaeoclimates were hot and dry. The principal sources of detritus lay to the Kunlun and Altun Mountains. The Lower Youshashan Formation is believed to contain good source rocks. The reservoir rocks consist of porosity clastic reservoirs and fractured reservoirs.