塔里木盆地巴楚—麦盖提地区石炭系混合沉积研究*

通过岩心、薄片观察，从岩石学特征入手，结合测井资料，对塔里木盆地巴楚—麦盖提地区石炭系的陆源碎屑—碳酸盐混积岩和混积层系进行了研究。根据混积强度将混积岩划分为混积型碎屑岩、混积型碳酸盐岩和高度混积岩。巴楚组下泥岩段和中泥岩段发育混积型碎屑岩，巴楚组生屑灰岩段、中泥岩段和小海子组发育混积型碳酸盐岩，卡拉沙依组上泥岩段、巴楚组下泥岩段及巴什托局部地区的中泥岩段发育高度混积岩。高度混积岩出现在海退期沉积的碎屑岩段，代表了陆源碎屑—碳酸盐强烈混合的过渡性沉积环境。研究区石炭系可识别出4个三级层序，混积层系主要发育在海侵体系域早期和高位体系域晚期，以间断混合和相缘混合为主。研究认为混积强度是评价混合沉积环境性质的主要参数，并将其划分为4级。下泥岩段存在混积强度达3级以上的混积界面，能用于地层对比。最后，结合混合沉积特征讨论了构造运动和海平面变化对研究区石炭系层序组以上的混合沉积的控制作用。

Researches of mixed sedimentation of the Carboniferous in Bachu-Makit area in Tarim Basin

The characteristics of clastic-carbonate mixed rocks and mixed bed series of the Carboniferous in Bachu-Makit area in the Tarim Basin were reported,through analyses of petrology,observation of cores,thin sections and well-log data.According to the intensity of mixed sedimentation,the clastic-carbonate mixed rocks are divided into mixed clastic,mixed carbonate rocks and high-mixed rocks.The Lower Mudstone and Middle Mudstone of the Bachu Formation were mixed clastic,while the bioclastic limestone of the Bachu Formation,Xiaohaizi Formation and Middle Mudstone of the Bachu Formation were mixed carbonate rocks,while high-mixed rocks distributed in the Upper Mudstone of the Karashayi Formation and Lower Mudstone of the Bachu Formation,as well as in the Middle Mudstone of the Bachu Formation partly in Bashituo area.The occurrence of high-mixed rocks in clastic of regression corresponded to the transition environment with intense clastic-carbonate mixing.There were four sequences identified in the Carboniferous in this area.The mixed bed series almost formed in the early stage of TST and later period of HST,with punctuated mixing and facies mixing domination.It is concluded that the intensity of mixed sedimentation can be used as a main indicator of evaluating the nature of mixed sedimentation environment,which can be divided into four orders.There was a mixed sedimentary surface in the Lower Mudstone of the Bachu Formation,where the intensity of mixed sedimentation reached the third order,and can be used in stratigraphic correlation.In conclusion,based on the characteristic of clastic-carbonate mixed sedimentation,the main controlling factors of mixed sedimentation were discussed,mainly including tectonic movement and eustatic change.