二连盆地马尼特拗陷砂砾岩体沉积类型及模式

Sedimentary types and depositional models of glutenite bodies in Manite Depression,Erlian Basin,China

通过对地震、岩心、测录井等资料综合分析,探讨内蒙古二连盆地马尼特拗陷早白垩世砂砾岩体的主要沉积类型和发育规律,总结其中的凹陷结构类型及边缘类型,识别所发育砂砾岩体的成因类型,并对各成因类型的特征、发育环境等进行总结,最终构建相应的沉积模式。研究表明:马尼特拗陷中的凹陷可分为简单单断式、单断断阶式和单断断槽式;在3种凹陷类型中识别出断裂陡坡型、断阶陡坡型、多级断阶型、挠曲缓坡型、断裂缓坡型、断阶缓坡型、无坡折缓坡型等7种凹陷边缘类型;拗陷内主要发育近岸水下扇、扇三角洲、辫状河三角洲、湖底扇等4种砂砾岩扇体类型。马尼特拗陷内部凹陷多属于较窄的小型断陷湖盆,较为适合扇三角洲、近岸水下扇发育;而盆缘作为重要的过渡地带,其构造古地貌特征对砂砾岩体的发育具有重要的控制作用。

The type and development law of early Cretaceous glutenites in the Manite Depression,Erlian Basin are studied by comprehensive analysis of integration of core data,well logging data and 3D seismic data in order to recognize the types of sag structures and sag edge,identify the genetic types of the glutenite bodies,summarize the characteristics and development environment of each genetic type,and finally establish the corresponding sedimentary model.The results show that the sags in Manit Depression can be divided into simple single fault type,single intermittent step type and single intermittent trough type.Among the three sag types,seven sag edge types are identified,including fault steep slope type,step-fault steep slope type,multi-step-fault type,flexural gentle slope type,fault gentle slope type,step-fault gentle slope type and gentle slope type without slope break.There are four types of glutenite fan body in the depression,including nearshore subaqueous fan,fan delta,braided river delta and sublacustrine fan.It is proposed that the depressions inside the Manit Depression belong to narrow and small faulted lake basins,which are suitable for the development of fan deltas and nearshore underwater fans.The basin margin is an important transition zone,and its tectonic palaeogeomorphology plays an important role in controlling the development of glutenite bodies.