摘要：

鄂尔多斯盆地上三叠统延长组广泛发育曲流河三角洲沉积，其总体沉积特征为：沉积体系及相带发育完整;成分成熟度及结构成熟度较高；发育各种沉积构造、动植物化石及生物遗迹构造。曲流河三角洲平原的分流河道具有复杂分支与决口历史，因此常呈交织状，受分流河道冲蚀作用的影响，河口坝不发育。曲流河三角洲主要形成于湖盆坳陷回返期。通过对岩相组合、骨架砂体的几何形态及盆地古地理背景的综合分析，认为延长组的环境演化反映了浅水台地型三角洲逐渐转变为陆上平原的过程。曲流河三角洲可形成良好的储层，是油气勘探的有利相带。

Abstract:

Meandering delta sediments were widely developed in the Yanchang Formation of Upper Triassic in Ordos BasinThe main characteristics of meandering delta are as follows:Meandering delta is relatively far away from the source area，and is asedimentary system in which various facies are relatively complete，grown size of sediments is fine and textural and mineral maturity are relatively highMineral composition is similar to that of source areaVarious sediment structures are developed，including trough and planarcross bedding，parallel bedding，smalescale bedding，wavebedding and horizontal bedding，animal and plant fossils and relic structuresIn plain part,submarine distributary channels of meandering deltaic plain have complicated branches and crevasse history which are interrelated.Mouth bar is not well preservedMeandering delta of Ordos Basin was mainly formed during the rebound of lake basin depressionWe studied the division and contract of the Yanchang Formation oil-bearing bed，the characteristic facies association，geometryof the skeletal sand bodies and the palaeogeographic patternIt was concluded that the shallowwater platform delta was gradually transformed into terrestrialplainMeandering delta in this region have great potential for oil and gas reservoirs，and is a favorable facies zone in oil and gas exploration