【摘要】 在露头分析的基础上,结合钻井和地震资料,提出四川盆地中二叠统茅口组发育碳酸盐岩斜坡相沉积。其典型岩性为深灰色砾屑灰岩,砾屑成分以生物碎屑泥晶灰岩为主,局部地区见亮晶生物碎屑灰岩、造礁生物和重力滑动变形构造,砾径变化范围大;次要岩性为含钙屑浊积岩的深灰色薄层泥晶灰岩。中二叠统从栖霞组开阔台地相到茅口组斜坡相的演化,说明茅口组沉积时期构造活动加强,导致盆地北部及其他区域都有可能发生相带的分异。茅口组地震剖面上的厚度由南向北明显增厚,且具有楔形反射的特征,印证了盆地北部斜坡相的南区发育有台地边缘高能相带,这一认识有利于对四川盆地茅口组构造-岩相古地理的重建以及有利相带和储层的预测。更多还原

【Abstract】 Through analyses of outcrops,wells and seismic profiles,it is proposed that carbonate slope facies develops in Middle Permian Maokou Formation in northern part of Sichuan Basin.The carbonate slope facies is of typical characteristics as follows:The lithology mainly is dark grey calcirudite,which is composed of bioclastic micrite in majority and sparry bioclastic limestone and reef-building organisms in minor with gravity gliding structure.The secondary lithology is dark grey thin-layered micrite with calcarenaceous turbidite.The evolution of sedimentary facies from Middle Permian Qixia open platform facies to Maokou slope facies reveals a fact of increasing tectonic activity during Maokou sedimentation which resulted in possible differentiation of sedimentary facies belts in northern Sichuan Basin beside other areas.The seismic profile illustrates that the thickness of Maokou strata increases obviously from south to north and is characterized by a sphenoid reflection,which proves the existence of a high-energetic platform-margin facies belt in the south of slope area in the northern part of the basin.This viewpoint is favorable to reconstructing structure-lithofacies paleogeology and predicting the potential sedimentary facies and reservoirs of Maokou Formation in the basin.更多还原