川东北地区嘉陵江组二段沉积相特征研究

Sedimentation Characteristics of Lower Triassic Jialingjiang 2nd Member in Northeast Part of Sichuan Basin

对岩心、薄片和测井资料及川东北地区下三叠统嘉陵江组二段的岩石类型、古生物化石、沉积结构、沉积构造等沉积相标志的分析认为,嘉陵江组二段为局限台地相和蒸发台地相沉积环境,具有台坪相、潮坪相及粒屑滩等亚相特征,包含白云岩坪、石灰岩坪、云膏坪、膏云坪及砂屑滩等沉积微相。嘉陵江组二段由下至上经历了从潮上蒸发环境(蒸发潮坪)到潮下相对低能环境(白云岩坪、石灰岩坪),再到潮上蒸发环境(蒸发潮坪)的一个完整的海进—海退沉积旋回,其中发育于潮下相对低能环境的砂屑滩、白云岩坪和石灰岩坪是油气储集的最有利相带。

Based on the analysis of rock types,fossils,sedimentary texture and sedimentary facies from rock cores,sections and logging data,it is suggested that the Lower Triassic Jialingjiang 2nd Member deposited in the environments of restricted sea and evaporation platforms in the northeast part of Sichuan basin,which is characteristics of platform flat,tidal flat and calcarenite bank subfacies.It has experienced an entire transgression-regression cycles from the supratidal evaporation environment（evaporation tidal flat） pass the low-energy subtidal environment（dolostone flat and limestone flat） then to another supratidal evaporation environment（evaporation tidal flat）.It is suggested that calcarenite bank,dolostone flat and limestone flat developing in the relatively low energy environment are the reservoirs most favorable for hydrocarbon accumulation.