【摘要】 白垩纪的库车坳陷是一个干旱气候条件下的内陆坳陷 ,其中只发育下白垩统 ,为一套干旱红层地层 ,进一步划分为亚格列木组、舒善河组、巴西盖组和巴什基奇克组。该套干旱红层 ,包括洪积扇砾岩、间歇性河流砂砾岩、风成砂岩和沙漠湖紫红色泥岩等沉积。这些沉积在地层记录中常以一种特别的旋回性形式产出 ,在不整合面及其相关面之上首先沉积的是洪积扇砾岩和间歇性河流砂砾岩所构成的冲积沉积物 ,向上逐渐演变为沙漠湖红色泥岩 ,在成湖初期或湖退期发育了滨湖相风成砂岩 ,它们构成了一个较为典型的沙漠沉积体系。从冲积沉积到湖泊沉积构成总体向上变细的沉积相序组合。按照地层记录的旋回性进行三级沉积层序划分 ,将库车坳陷下白垩统划分为 5个三级沉积层序即SQ1至SQ5。下白垩统的顶和底界面均为间断时间很长的区域不整合面 ,由它们所限定的下白垩统本身则构成一个二级构造层序 ,在二级构造层序内三级沉积层序常常形成有规律的叠加形式 ,下部的SQ1和上部的SQ5发育较多的冲积粗碎屑物 ,中部SQ2 至SQ4则以湖泊相沉积为主。与海相地层不同 ,库车坳陷白垩系中由三级层序和二级层序所代表的地层记录中的中周期和长周期旋回的主要控制因素是幕式构造沉降 ,沉降初期由于地形高差大而以发育冲积粗碎屑物为主 ,均衡沉更多还原

【Abstract】 The Cretaceous in the Kuqa Depression was an arid intra continental depression,in which only the Lower Cretaceous marked by a set of arid red bed was developed and could be divided into the Yageliemu Formation,the Shushanhe Formation,the Baxigai Formation and the Bashijiqike Formation Several types of sediments constitute this set of arid red bed,i e pluvial fan conglomerates,intermittent river sandy conglomerates,aeolian sandstones and desert lake purple mudstones These sediments of the Cretaceous in the Kuqa Depression made up a typical desert sedimentary system The cyclicity in stratigraphic records are reflected by the alternation between the coarse clastic pluvial sediments in the lower part and the fine desert lake sediments in the upper part Aeolian sandstones were formed in the initial stage and the regressive stage of the lake forming period According to the cyclicities in the stratigraphic records represented by the sedimentary facies succession,i e the succession constituted by pluvial coarse clastic sediments in the lower part and fine desert lake sediments in the upper part,the Lower Cretaceous in the Kuqa Depression could be divided into five third order sedimentary sequences,i e SQ1 to SQ5 Because the top and bottom boundaries of the Lower Cretaceous in the Kuqa Depression are obvious tectonic unconformities,the Lower Cretaceous in the Kuqa Depression makes up a second order tectonic sequence There is regularly vertical sacking pattern for third order sedimentary sequences in the second order tectonic sequence This feature is reflected by that more coarse pluvial clastic sediments were developed in SQ1 and SQ5,and the middle part of the Lower Cretaceous in the Kuqa Depression made up by SQ2 to SQ4 was always developed with more fine desert lake sediments Different from marine strata,the cyclicities represented by sequences in stratigraphic records in the Lower Cretaceous of the Kuqa Depression are mainly caused by the episodic tectonic subsidence Due to a high difference of toporgraphy,more coarse clastic pluvial sediments were formed in the initial stage of sedimentary basin subsidence,corresponding to the isostatic subsidence stage during which the lake was formed and more fine desert lake sediments were developed On the basis of sequence stratigraphy,the palaeogeographical visage as well as the evolution process of sedimentary facies and palaeogeography for the Cretaceous of the Kuqa Depression are clearly reflected by a series of the panel diagram of sequence stratigraphic frameworks and their corresponding outline maps of sedimentary facies and palaeogeography更多还原