北祁连-河西走廊志留纪和泥盆纪古地理及其对同造山过程的沉积响应

北祁连-河西走廊志留系包括下志留统鹿角沟砾岩和肮脏沟组、中志留统泉脑沟山组和上志留统旱峡组，泥盆系包括中、下泥盆统老君山组和上泥盆统沙流水组。鹿角沟砾岩为水下冲积扇沉积，断续分布于北祁连西段。肮脏沟组在北祁连-河西走廊分布广泛，主要为半深海碎屑复理石沉积。泉脑沟山组和旱峡组分布于北祁连和河西走廊西段，前者以浅海相砂泥岩和泥灰岩为主，后者以滨海潮坪-浅海碎屑岩沉积为主。老君山组分布于古祁连山山前和山间盆地，为粗碎屑磨拉石沉积。沙流水组分布于河西走廊东段，为湖相沉积。区域古地理分析表明，北祁连-河西走廊志留纪-泥盆纪的古地理主要受北祁连加里东-早海西期不规则造山作用控制。鹿角沟砾岩标志着弧-陆碰撞最早发生于早志留世早期。早志留世北祁连-河西走廊由弧后残余盆地向前陆盆地转化。中、晚志留世北祁连东段剧烈造山并与阿拉善古陆的连接，前陆盆地限于北祁连-河西走廊西段。志留纪末期为北祁连的主造山期，泥盆纪形成高峻的古祁连山。早、中泥盆世形成山前和山间盆地的粗碎屑磨拉石沉积。晚泥盆世造山带西段造山作用剧烈，形成剥蚀区。东段造山作用微弱，山地被剥蚀，山前形成湖泊相的晚泥盆世沉积。

SILURIAN AND DEVONIAN PALAEOGEOGRAPHY OF NORTHERN QILIAN-HEXI CORRIDOR AND ITS SEDIMENTARY RESPONSE TO SYNORNGENESIS OF NORTH QILIAN OROGENIC BELT

Silurian of Northern Qilian Mountains- Hexi Corridor consists of the Early Silurian Lujiaogou Conglomerate and Formation, the Middle Silurian Quannaogoushan Formation and the Late Silurian Hanxia Formation. Devonian consists of the Early and Middle Devonian Laojunshan Formation and the Late Devonian Shaliushui Formation. Lujiaogou Conglomerate is intermittently distributed over the western section of the Northern Qilian Mountains and is the deposits of submarine alluvial fan. Angzanggou Formation is widely distributed over the Northern Qilian Mountains- Hexi Corridor and is mainly bathyal flysch deposits. Quannaogoushan Formation and Hanxia Formation are distributed the western regions of the Northern Qilian Mountains- Hexi Corridor. Quannaogoushan Formation is composed of the neritic deposits of sandstone, mudstone and marlite, and Hanxia Formation of the littoral and neritic sandstone and mudstone. Laojunshan Formation is dispersed over the piedmont and intermountainous basin of paleo-Qilian Mountains and is composed of coarse clastic molasse. Shaliushui Formation is distributed over the eastern region of the Hexi Corridor and is composed of sandstone and mudstone of lacustrine facies. Silurian and Devonian regional palaeogeography is controlled by the irregular orogenic process of North Qilian from Caledonian to Early Hercynian. Lujiaogou Conglomerate is the sedimentary response to arc-continental collision during the earliest of Silurian. In the Early Silurian，the Northern Qilian Mountains- Hexi Corridor transforms from back-arc survival basin to foreland basin. In the middle and late Silurian, the orogeny in eastern part of North Qilian is strong. Connection between the eastern part of the orogenic belt and Alashan paleo-continental formed a disintegrating area. Foreland basin is merely located in the western region of North Qilian and Hexi Corridor. The Latest Silurian is main orogenic stage of North Qilian. Devonian Qilian mountains is high and the Early and Middle Devonian molasse formed in the piedmont and intermountainous basin of paleo-Qilian Mountains. In the Late Devonian the orogenic process is strong in the western part of the orogenic belt and formed a disintegrating area. The Late Devonian deposits of lacustrine facies formed in the eastern region of the Hexi Corridor.