粗粒辫状河心滩内部泥质夹层分布新模式--以吴官屯野外露头为例

New distribution pattern of mudstone interlayer within batture bar reservoir of braided river-a case study of field outcrops in Wuguantun

通过对山西省大同市吴官屯侏罗系辫状河沉积露头观察、测量及成因分析，对该露头进行了3～5级构型解剖。此处沉积体垂向发育三期辫状河道砂体，期次之间发育稳定的细粒沉积物；在单期河道砂体内部，发育辫状河道和心滩两个4级沉积构型单元，其中，心滩主要为辫状河砂体类型；在单一心滩内部，发育多个增生体，增生体之间界面处发育沟道及落淤层，均为细砂岩充填，未见泥质夹层。在以上解剖基础上，综合其它同类型辫状河心滩沉积特征，最终得到了粗粒辫状河心滩级次及内部细粒沉积单元分布模式。

Through observation,measurement and origin analysis of filed outcrops in Jurassic braided river deposits in Wuguantun,Datong,Shanxi,an accurate architecture anatomy study of 3-5 orders has been carried out.In vertical direction,it developed channel sand bodies in three periods and there were stable fine sediment exists between them.Within the single channel sand body,two 4th order architecture units,namely braided channels and channel bars,were developed,among which,the batture bar reservoir was the main type of sand bodies.Among the single batture bar reservoir,it developed multiple accreting bodies and between the accreting bodies it developed channels and falling-silt seams,which were filled by fine sandstone and there were no mudstone interlayer.Based on the architecture anatomy mentioned above,in combination with the sedimentary characteristics of the similar kinds,the distribution pattern of the batture bar reservoir of coarse-grained braided river and internal fine sedimentary units have been finally established.