徐州大北望地区寒武系陆表海沉积特征及其演化

Cambrian epicontinental deposit characteristics and evolution in the Dabeiwang of Xuzhou

徐州大北望地区寒武系为华北地台陆表海环境的典型沉积建造,寒武系碳酸盐岩生油潜力及储集层发育情况都有待于研究。通过分析该区寒武系岩石学及陆表海沉积环境特征,恢复了区域海平面变化、周期及古地理环境。综合野外露头与室内分析,研究区寒武系主要发育的岩石类型为碳酸盐岩,其中鲕粒灰岩厚度较大。该区寒武系陆表海环境中发育沉积相类型主要有潮坪、滩相、滩间海、局限海。该区沉积演化为早寒武世主要以潮坪沉积为主,中寒武世发生了寒武系最大一次海侵,台地鲕粒滩相较发育,晚寒武世水深逐渐变浅,出现局限海、潮坪环境。台地浅滩相中发育的鲕粒灰岩及白云岩为较有利储集岩,该区寒武系云坪沉积具有潜在油气储集意义。

The Cambrian deposition in the Dabeiwang of Xuzhou is a typical sedimentary formation of epicontinental deposit developed on the North China platform.Oil generation potential and reservoir development in the Cambrian carbonate rock remain to be further examined.Regional sea-level changes,cycles and paleo-geographic environment are restored through analysis of the Cambrian petrology and epicontinental deposit characteristics.Outcrop and laboratory analysis show that the Cambrian in the study area is dominated by carbonate rock,with oolitic limestone being thicker.The sedimentary facies developed in the Cambrian epicontinental sea environment include tidal flat,beach,interbank sea and restricted sea facies.The sedimentary evolution can be divided into three stages,which are tidal flat deposit in early Cambrian,platform oolitic beach facies in middle Cambrian when the biggest transgression happened in the Cambrian,and then restricted sea and tidal flat environments as water depth became gradually shallower in late Cambrian.Analysis shows that the oolitic limestone and dolomite developed on carbonate platform shoal are favorable hydrocarbon reservoirs in the study area.The Cambrian tidal flat deposits are potential oil and gas reservoirs in this area.