大型坳陷型湖盆浅水三角洲沉积特征及沉积相模式——以松辽盆地茂兴-敖南地区泉四段为例

Sedimentary Characteristics and Mode of Shallow Delta in Large Scale Downwrap Lacustrine Basin——By Taking Quan-4 Formation in Maoxing and Aonan Region in Songliao Basin for Example

松辽盆地北部茂兴-敖南地区泉四段以泥岩、粉砂质泥岩和粉砂岩沉积为主,夹少量细砂岩沉积。通过对泥岩颜色、古生物化石、粒度分布、沉积构造等沉积特征分析,确定研究区泉头组四段为一套浅水三角洲沉积,发育三角洲平原和三角洲前缘两种沉积亚相,其中以分流河道和决口河道发育为主要特征,反映河道不断分岔和决口改造的特点。在此基础上编制了该区沉积微相平面分布图,建立了茂兴-敖南地区泉四段浅水三角洲沉积模式,为进一步提高扶余油层的勘探开发程度奠定了地质基础。

Quan-4 member of Songliao Basin was mainly consisted of mudstone, silty mudstone and siltstone, which was included less fine sandstone sediments. By analyzing the characteristics of mudstone colors, fossils, granularity distribution and sedimentary structures, Quan-4 member in the studied area is confirmed as shallow delta depositional system.It develops delta plain and delta front subfacies, distributary channel and crevasse channel are the main characteristics, which reflects channel bifurcation and crevasse transformation. Based on this, The distribution maps of sedimentary microfacies of Maoxing and Aonan are drawn and the shallow delta depositional model of this region is established, it provides geologic foundation for farther exploration and development in Fuyu Reservoir.