Abstract: Based on description of outcrop section and cores，drilling well and logging and seismic data，the types of sedimentary facies and their characteristics of the Paleogene and Neogene were studied in the north margin of Qaidam Basin.The research showed that alluvial fan，fan delta，braided fluvial，braided fluvial delta and lacustrine facies were developed in the Paleogene and Neogene.The sedimentary spatial-temporal distribution was affected by the structural framework of basin base，the growth thrust faults of altun slope，the thrust fault in the north margin and palaeo-high land，bringing about the sedimentary system with diversity.By the effect of thrust faults and palaeo-high land，alluvial fan，fan delta and lacustrine facies were present in Lenghu-area，and alluvial fan-braid braided river delta were present in Mahai-Nanbaxian area.The systematic analysis about palaeogeographic evolution was achieved based on the sedimentary facies analysis，and more reliable geological information was provided for the further exploration.

Key words: sedimentary facies, palaeogeography, Paleogene and Neogene, Qaidam Basin

摘要： 根据野外露头剖面和岩心观察，钻、录井及测井曲线以及地震等资料，研究了柴达木盆地北缘古近系—新近系的沉积相类型和沉积特征，结果表明该区主要发育冲积扇、扇三角洲、辫状河、辫状河三角洲及湖泊等沉积相类型。柴达木盆地北缘的沉积时空展布受盆地基底的构造格架及阿尔金山斜坡带生长逆冲断裂系、北缘逆冲断层和古隆起的联合作用，沉积体系具有多样性。冷湖地区受逆冲断层作用，发育了冲积扇—扇三角洲—湖泊沉积体系；马海—南八仙地区则受逆冲断层和古隆起的双重控制，发育冲积扇—辫状河—辫状河三角洲—湖泊沉积体系。在沉积相分析的基础上对古地理演化进行了系统分析，为下一步的油气勘探工作提供可靠的地质资料。

关键词: 沉积相, 古地理, 古近纪—新近纪, 柴达木盆地

CLC Number: 

• P521