库车坳陷北部白垩系沉积速率分析

库车坳陷白垩纪经历了一个相对独立的一级构造旋回,结合坳陷北部库车河白垩系剖面详细的磁性地层学结果,应用地层回剥分析方法恢复了库车坳陷白垩系时期的沉降历史,计算得到亚格列木组、舒善河组、巴西盖组、巴什基奇克组沉积速率,分别为11.5 cm/ka、2.5 cm/ka、2.9 cm/ka、1.7 cm/ka。结合裂变径迹资料和岩相古地理特征,将库车坳陷白垩系沉降历史分为四个演化阶段:（1）Berriasian中期（141.9141.2 M a）:极快速沉降;（2）Berriasian中晚期至A lb ian中晚期（141.2101 M a）,持续缓慢沉降;（3）A lb ian末期至Campan ian早期（10179.1 M a）:构造隆升,沉积剥蚀;（4）Campan ian中晚期—M aastrichtian期（79.165.6 M a）:极慢速沉降,接受沉积。早白垩世早中期沉降曲线呈“上凹”特征,反映了构造活动由早期剧烈沉降到后期减弱,最后趋于稳定的过程。该沉降过程与典型的前陆盆地挠曲沉降过程并不一致。 

The Sedimentation Rates Analysis of Cretaceous Depositional Succession in the Northern Kuqa Depression, Northwest China

High-resolution chronostratigraphic framework has been established through the detailed magnetostratigraphic study on Cretaceous succession in the Kuqa River and Kezilenuer Channel profiles.On the basis of the results,subsidence history in Cretaceous of Kuqa depression is recovered by back-stripping method.Sedimentation rates of Yageliemu,Shushanhe,Baxigai and Bashenjiqike formation are calculated with a result of 11.5cm/ka,2.5cm/ka,2.9cm/ka and 1.7cm/ka,respectively.Combining with the data of fission track and paleogeography,subsidence history in Cretaceous of Kuqa depression can be divided into four stages,(1) middle Berriasian(141.9-141.2Ma): sharp subsidence;(2) middle-late Berriasian to middle-late Albian(141.2-101Ma): slow subsidence;(3) at the end of Albian to early Campanian(101-79.1Ma): tectonic uplift and ablation of sedimentation;(4) middle-late Campanian-Maastrichtian(79.1-65.6Ma): slow subsidence and sedimentary.Characteristic of "concave upwards" in the subsidence curve of the middle-late phases in early Cretaceous reflects the process of tectonic activity that from early sharp subsidence to late weaken,and incline to stabilize finally,which indicates that Kuqa depression has no the characteristic of foreland basin in the early Cretaceous.