摘要： 古近纪是塔里木盆地由海向陆转化的时期。当时该区的海侵来自研究区西侧的古地中海分支,物源则主要是盆地北部的南天山以及南部的昆仑山,沉积中心在库车坳陷西部以及塔西南坳陷带的西部。古新世-始新世早期(库姆格列木群沉积期)在盆地北部库车坳陷发育砾岩、砂岩、碳酸盐岩及膏盐岩,沉积环境有滨岸、湖、潮坪及扇三角洲等,塔西南坳陷以碳酸盐岩和膏岩为特征,从东到西发育开阔台地、近岸局限台地、蒸发盐台地、辫状河三角洲环境等,二者之间即在塔北隆起及北部坳陷带位置为宽阔的古隆起区。始新世晚期-渐新世 (苏维依组沉积期)整个盆地以滨浅湖为主,发育粉砂岩与泥岩互层沉积,塔西南坳陷虽然仍发育多个海相层,但海水的影响明显比始新世早期弱,当时主要古地理单元有海湾、湖、滨浅湖、扇三角洲和辫状河三角洲。总体上,塔里木盆地在古近纪经历了早期以扇三角洲为主的浅水环境到晚期的滨浅湖及海湾、湖环境, 古近纪研究区的古气候以热带-亚热带的干旱气候为主。

关键词: 塔里木盆地, 库车坳陷, 塔西南坳陷, 古近系, 古地理, 沉积相

Abstract: The Paleogene is a period when the Tarim Basin transformed from a marine influenced to a non-marine influenced basin. The marine transgression in the basin was from the northern branch of the Tethy to the west. The sediment provenances were the old southern Tianshan to the north and the old Kunlun Mountains to the south, and the depocenters were located at the western Kuga Depression and the western Southwestern Tarim Depression. From the Paleocene to the Early Eocene (during the deposition of the Kumugeliemu Group and its equivalents), the Kuga Depression was developed with shoreline, lagoon, tidal flat and fan delta environments, and was lithologically dominated by conglomerates, sandstones, carbonates and gypseous rocks. The Southwestern Tarim Depression was developed with open platform, nearshore restricted platform, evaporate platform, and braided delta environments, and lithologically dominated by carbonates, gypseous rocks and coarse sand stones These two old depositional depressions were separated by an extensive palaeo-uplift which coincided with the current Northern Tarim Uplift and Northern Depression structural zones. From the Late Eocene to Oligocene (during the deposition of the Suweiyi Formation and its equivalents) , the entire Tarim Basin was mostly submerged and was developed with a wide coastal to shallow lake that received deposition of interbedded siltstones and mudstones. The marine successions were restricted to the west ern corner of the Southwestern Tarim Depression and marine influence became less evident than that in the Paleocene to the Early Eocene. The paleogeographic units of this period were mainly estuarine, lagoon, littoral shallow lacustrine, as well as braided deltas On the whole, during the Paleogene, the Tarim Basin experienced a shallow water environment dominated by fan deltas of the early phase and the littoral to shallow lacustrine environment of the late phase, with a tropical to subtropical arid paleoclimate Paleogene.

Key words: Tarim Basin, Kuga Depression, Southwestern Tarim Depression, palaeogeography, sedimentary facies

中图分类号: 

• P618

• 130.1