湖泊三角洲前缘砂体成因组合形式和分布规律--以鄂尔多斯盆地姬塬白豹地区三叠系延长组为例

以鄂尔多斯盆地姬塬白豹地区三叠系延长组为例,系统讨论了湖泊三角洲前缘砂体的成因类型及组合形式.从成因类型上看,三角洲前缘砂体包括:(1)水下分流河道砂体;(2)河口坝砂体;(3)远砂坝砂体;(4)席状砂砂体.从组合类型上看主要包括:(1)叠置的水下分流河道砂体;(2)叠置的河口坝砂体;(3)水下分流河道-河口坝组合砂体;(4)席状砂-远砂坝-河口坝组合砂体等.在此基础上,详细论述了三角洲前缘砂体组合形式的时空分布规律.

Origin and association types of lake delta front sandstones and their distribution patterns of Triassic Yanchang Formation in Ordos Basin, China

Taking the Yanchang Formation of Triassic System in Jiyuan and Baibao area in Ordos Basin as example, this paper discusses in detail the origin and association types of lake delta front sandstones and their distribution patterns. The delta front sandstones include (1) subaqueous distributary channel sandstone; (2) channe-mouth bar sandstone; (3) distal bar sandstone and (4) front sheet sandstone. According to association type the sandstones include (1) superimposed distributary channel sandstone; (2) superimposed channel-mouth bar sandstone; (3) subaqueous distributary channel sandstone and channel-mouth bar association sandstone and (4) channel-mouth bar, distal bar and front sheet association sandstones. The distribution of above association types links closely with the vertical evolution and is controlled by provenance supplies, lake level change and basement depression.