北祁连东部石炭纪岩相古地理

〗通过对石炭系实测剖面岩石的岩性、岩相、结构构造、粒度、古生物组合和古生态等特征的综合分析，利用石油勘探成果，研究了北祁连东部石炭纪岩相古地理。早石炭世早期，秦岭海域海水以天水—静宁古海峡为通道，向北侵入本区，形成由鄂尔多斯、阿拉善和陇西三大古陆围限的祁连海海湾沉积区,以咸化泻湖相、滨浅海相沉积为主，早石炭世晚期，海侵进一步扩大，以滨浅海相碎屑岩、碳酸盐岩沉积为主。晚石炭世海盆继续向东、向北扩展，海侵次数增多，形成了多个以碎屑岩为主夹灰岩沉积的海侵海退旋回，晚石炭世晚期太原组沉积时期，海水向东与华北海相连，成为广阔的陆表海沉积。中部地区存在近东西向分布的链岛状古隆起及水下隆起，古地形具西高东低、北高南低的特征。

Lithofacies Paleogeography of the Carboniferous in the East of North Qilian Mountains

The characteristics of Carboniferous lithofacies palaeogeography in the east of North Qilian Mountains have been discussed based on the analysis on outcrop sedimentary facies,clastic composition,particle size,rock texture and structure,paleontology,paleoecology.Shore-shallow marine facies,lagoon facies,delta facies and eleven sedimentary subfacies have been identified.In the early period of early Carboniferous,the marine water invaded the area from Qinling through the Tianshui-Jingning strait,resulting in a gulf surrounded by Alashan,Ordos,Longxi oldlands,mainly with salted lagoon facies and shore-shallow facies.In the late period of early Carboniferous,the transgression area became progressively extended,mainly with clastic rock and carbonate rock of shore-shallow marine facies.In the period of late Carboniferous,the transgression became high frequency,with several transgression and regressive cycle.In the period of Taiyuan Formation sediment,the North Qilian sea water conjoined with Ordos sea water to expand epicontinental sea.The chain shape uplift and below water uplift distribute into the Qilian marine basin.Palaeotopography is characteristic of high west and north,low east and south.