浅谈赣东北上二叠统龙潭组层序地层、古地理与乐平煤

Upper Permian Longtan Sequence Stratigraphy,Paleogeography and Leping Coal in Northeastern Jiangxi Province

赣东北上二叠统龙潭组为一个完整的准二级层序,含15个三级层序,按体系域分七个阶段描述了古地理特点。垂向上水体由浅至深再至浅,横向上南浅北深,有官山段上部、狮子山段、王潘里段上部三个障壁形成期。赣东北龙潭期含煤建造,多数是在潮汐为主的水动力条件下形成的,成煤环境与潮汐带伴生在一起,不同成煤环境形成不同的煤。退积型平缓潮坪,分内、中、外三种亚环境,分别形成富镜质组树皮煤、贫镜质组树皮煤、富镜质组含树皮煤;障壁后潮坪形成富镜质组富树皮煤;三角洲平原和滩脊带形成腐植煤。真正质量最好的乐平树皮煤,只发育在退积型平缓潮坪的中带。不同类型的煤,生烃条件大不相同。

The Upper Permian Longtan Formation is a complete 2nd-order parasequence that includes fifteen 3rd-order subsequences in the northeast Jiangxi province. The paleogeographic ehacracteristics of Longtan sediments in vertical and lateral is described according to sedimentary system tract that is divided into 7 stages. Three phases of barriers formed during Longtan age, which are the upper Guan- shan Member, Shizishan Member and the upper Yupanli Member. Environments of coal formation are commonly relative with tidal hydrodynamics and different sorts of coals that formed under different tidal flat environments are of quitely different hydrocarbon-generating conditions. The best quality of coal that can generate hydrocarbon is the Leping bark coal, which only developed in the middle zone of de- grading gentling tidal fat.