准噶尔盆地车排子地区白垩纪古地貌及其对沉积的控制

为了明确准噶尔盆地车排子地区白垩系砂体展布规律及沉积体系特征,运用印模法与层序地层学相结合的方法,通过建立层序地层格架、目标层选取、残余厚度求取、真厚度校正及地层压实恢复,对车排子地区白垩系进行了古地貌恢复,并分析了古地貌对沉积体系的控制作用。研究表明:车排子地区白垩系沉积时期总体上呈现西北高、东南低特征,西北部为隆起区,是剥蚀尖灭区域;相邻斜坡带呈谷梁相间的地貌特征,并发育侵蚀坡折带、断裂坡折带等不同类型的坡折带,东部—东南部为洼陷区,地形较为平缓;古地貌对沉积的控制主要表现为斜坡带内发育有不同规模、不同类型的坡折带,导致可容纳空间突然增大,控制着扇三角洲的发育,谷梁地貌控制了湖盆的水体范围和相对深度、水动力强弱及物源的搬运通道和卸载场所,使得研究区发育沿岸线近南北向不连续展布的滩坝砂体。

Cretaceous paleogeomorphology and its control on the sedimentation in Chepaizi area of Junggar Basin

In order to clarify Cretaceous sandbody distribution rule and sedimentary system characteristics in Chepaizi area of Junggar Basin, with the help of the integrated method between impression block and sequence stratigraphy, and moreover by means of establishing the sequence stratigraphic framework, calculation of the residual thickness, true thickness correction and formation compaction restoration, the Cretaceous paleogeomorphology in Chepaizi area was restored, and furthermore the controlling action of the paleogeomorphology on the sedimentary system was analyzed. The study shows that the Cretaceous paleogeomorphology in the study area is generally high in the northwest and low in the southeast, the uplift region is located in the northwest, which is the denuded and pinchout area;the adjacent slope belt is characterized by valley-hill geomorphology, different types of the slope break belt such as erosional and fault ones are developed, the depression zone is located in the east and southeast parts, which terrain is pretty gentle;the control of the paleogeomorphology on the sedimentation is mainly shown in different scales and different types of the slope break belt in the slope belt, thus result in the sudden increase of the accumulating and holding space, and moreover the control of the development of the fan delta, the valley-hill geomorphology dominates the the water range and its relative depth, the hydrodynamic intensity, the transport channel and unloaded site of the material source in the lake basin, which makes the beach-bar sandbody discontinuously distributes along the coastal line from south to north in the study area.