库车前陆盆地白垩系层序地层样式及控制因素分析

白垩系库车坳陷是在南天山强烈逆冲导致的挠曲沉降背景下发育的前陆盆地。综合地震、钻井和露头资料对白垩系进行了层序地层划分,共分出2个区域性的沉积旋回或构造层序、8个三级层序;区内各层序及其内部体系域总体呈现东西向展布、南北向分异的特点;建立了两种层序地层学框架模式:卡普沙良群构造层序具有典型前陆盆地挤压深陷特征,沉积构成反映了从前陆逆冲挠曲沉降到回弹上隆的演化过程;巴什基齐克组构造层序具有宽缓、伸展的特点,层序地层框架模式及内部地层构成样式有其独特性。白垩系前陆盆地的层序地层格架和沉积体系域的配置受到前陆构造作用的控制,而气候及湖平面变化则主要影响层序地层格架内的沉积相类型。 

Analysis of the Cretaceous Sequence-stratigraphic Pattern and Controlling Factors in Kuna Foreland Basin

The cretaceous Kuqa depression is a foreland basin generated by flexural subsidence resulting from the southward thrusting of the southern Tianshan Mountains. This paper has divided Cretaceous sequence stratigraphy of Kuqa foreland basin into two tectonic sequences and eight 3rd order sequences based on outcrops, well loggings and seismographic profiles. The sequences and system tracts in the Kuqa foreland basin spread from east to west as a whole and vary obviously from south to north. Two different models of sequence stratigraphic framework were established through studying the internal composition of sequence strata and boundary of individual sequences. In the kapushaliangqun group, this basin appeared as a strong compressive piedmont alluvial-hungry basin, a typical foreland basin. The development of sequence is attributed to the foreland tectonic process from flexural subsidence caused by thrust loading to rebounded uplift due to the erosion and stress release. In contrast, the basin shows smooth and expansive features in the bashijiqike age,and it has a unique model of sequence stratigraphy framework and special internal stratigraphic composition. The sequence framework and depositional pattern of the Cretaceous foreland basin were predominantly determined by the foreland tectonism and the changes of climate mainly impacted on sedimentary facies within sequence frameworks.