库车坳陷新生界低弯度河三角洲沉积

根据观察露头、岩心和分析钻井、测井资料，识别出塔里木盆地库车坳陷新生界中的低弯度河三角洲沉积。这种新发现的沉积类型是低弯度河进入极浅水湖泊形成的三角洲沉积，与正常三角洲沉积的区别是砂岩较粗，与辫状河三角洲沉积的区别是砂岩含量较低，与扇三角洲沉积的区别是缺少重力流沉积。库车坳陷新生界低弯度河三角洲相的亚相类型主要是三角洲平原亚相和三角洲前丝亚相，主要砂体类型为三角洲平原分流河道砂体和三角洲前缘水下分流河道砂体，原生粒间孔隙发育，渗透性好，是良好的储集层。低弯度河三角洲沉积以厚层状含砾不等粒砂岩及粉砂岩为主，单一砂砾岩层由多个正韵律层组成，厚度多为1－4m，底部具大型槽状和中型板状交错层理，常见侧积交错层理。图3表2参14（旷红伟摘）

The low sinuous river delta system of Cenozoic system in Kuqa depression of Tarim basin

A new sedimentary system-the low sinuous river delta system was identified by observing many outcrops and rock cores, laboratory investigation and analyzing some logging and drilling data in Cenozoic in Kuqa depression, Tarim basin. This delta formed by the low sinuous river flowing into the shallow lake is very different from braided delta, normal delta and fan delta due to its coarser sandstone, the lower sand content and absence of turbidities. The deposits of the low sinuous channel and the subaqueous channel are the main bodies for this type of delta and mainly consist of blocked, non equal grain size and pebbly sandstones and sandstones. A single sequence is of 1to 4m thick, partly less than 1m, but locally up to 6m, and is made up of many fining upward rhythms which vary from 0.1 to 0.8m thick and consist of 3 to 4 differential grain sizes rocks, such as pebbly sandstones, coarse sandstones and mid to fine sandstones upward. Big trough cross stratifications and mid planar cross stratifications are developed on the base of the sandstone beddings. The lateral accretion cross beddings are also observed in the sequences. Sandstones with well developed primary pores and good permeability are excellent reservoirs.