吐鲁番－哈密盆地的两种粗碎屑三角洲

吐鲁番－哈密盆地上二叠统、三叠系和侏罗系广泛发育冲积扇、河流、湖泊、扇三角洲、辫状河三角洲和正常三角洲相沉积。其内扇三角洲和辫状河三角洲最为发育，二者在岩石类型、沉积结构、沉积构造、沉积韵律、沉积旋回、沉积背景及岩电组合上有很大的相似性，其骨架主要为河道砂体。这两种粗碎屑三角洲可用其特征的陆上沉积组合来区分。本区的扇三角洲和辫状河三角洲具有良好的储集油气潜能，是今后油气勘探不可忽视的相带。

Two Types of Coarse Claslic Delta in Turpan Hami Basin

The Upper Permian, Triassic and Jurassic strata in the Turpan Hami basin have a wide distribution of alluvial fan, fluviolacustrine deposit, fan delta, braided delta and normal delta deposit, which are most characterized by the fan delta and braided delta deposits whose skeletons are mainly channel sandbodies. Fan delta is a coarse clastic delta formed by direct progradation of alluvial fan into shore shallow lakes. Its overwater portion is an alluvial fan and the submerged part is mainly an underwater distributary channel that is overlying the others. Braided delta is a coarse grained delta formed by progradation of braided river into shore shallow lakes, its over water portion is a braided plain mainly composed of braided channel and the submerged is mainly underwater distributary channels, which are overlain each other. Fan delta and braided delta can be distinguished by the characteristics of their underwater compositions. The former is sheetflood, debris flood and braided channel deposits and the latter is just braided channel deposits. Braided delta, owing to the better sorting, coarser grain and lower mud content in its reservoir and the better lateral continuity of various rock phases, has great potential of oil and gas reservoirs. In contrast, fan delta is a worse oil and gas reservoir because of the worse sorting, coarse grain and higher mud content and the worse lateral continuity of various phase zones. However, fan delta may also become a favoured reservoir in the special condition of stratigraphic traps. Braided delta and fan delta in this region have great potential of oil and gas reservoirs and are nat negligible phase zones in the further oil and gas exploration.