青藏高原东北缘的祁连山，在早白垩世期间发生明显隆升，受区域性构造运动和白垩纪特殊行星风系的影响，在山前盆地中沉积了一套特殊的碎屑岩序列。兰州盆地下白垩统发育完整，虽然局部被第四系覆盖，但总体出露良好，其特殊的相序单元构成的非常规体系域概念框架下的陆相层序地层学模式，对研究祁连山隆升的沉积学响应及环境效应具有重要意义。兰州盆地下白垩统为河口群，可以识别出5个三级层序（S ．1 S ．5），包括LAST和HAST两个非常规体系域，冲积扇和河流相粗碎屑沉积构成三级层序的LAST单元，HAST单元由湖泊相细碎屑地层组成。河口群上部地层发育的风成砂岩序列，在一定程度上可以解释为祁连山隆升造成的“焚风效应”产物，对研究祁连山的阶段性隆升特征具有重要的意义。早、晚白垩世之交，祁连山开始快速强烈隆升，兰州盆地整体抬升为剥蚀区，导致研究区缺失上白垩统。因此，兰州盆地下白垩统特殊的层序地层序列，不仅是早白垩世祁连山隆升的物质记录，还为研究早白垩世东亚大气环流格局变化提供了物质基础。%Controlled by the uplift of Qilian Mountains and the change of climate ,a set of clastic rocks are developed in Early Cretaceous in the continental basins in front of Qilian Mountains . The Cretaceous strata are developed and outcropped well in Lanzhou basin ,which are made up of particular sedimentary facies successions under the framework of the unconventional system tracts ,and are very important to the study of the Qilian Mountains uplift and their impacts on the Asian environment .The Lower Cretaceous Hekou Group can be divided into 5 third‐order sequences (S .1 S .5) ,and every third‐order sequence contains LAST and HAST unconventional systems .Alluvial fan facies and fluvial facies coarse clastic rocks constitute the LAST ;while the HAST is composed by alluvial fan facies .The eolian sandstones in the Upper Part of Hekou Group are the products of “foehn effect” caused by the Qilian Mountains uplift .In the transition period of Early to Late Cretaceous ,Qilian Mountains uplifted fast and intensively ,which caused the denuded zone of the study area ;so the Upper Cretaceous strata were not developed .The Lower Cretaceous sequences of Lanzhou basin are the material records of not only the Qilian Mountains uplift ,but also the reconstruction of the pattern of the atmospheric circle in East Asia .
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