摘要:
通过对抚顺聚煤盆地的沉积动力学研究及对古城子组主要煤层的煤体形态、沉积构造及夹矸特征、大型树桩化石等的详细观察,对主煤超厚煤层的沉积环境进行了深入细致的分析。结果表明,主煤超厚煤层主要沉积于较深水的沉积环境,内碎屑沉积作用活跃,可作为深水成煤模式的典型代表。
Abstract:
Numerous Meszoic Cenozoic small scale fault basins in China contain extermely thick coal seam with low ash content,but it is difficult to explain the genesis of such kind of coal seam only by in situ coal forming theory.Based on the research of the depositional dynamics of Fushun coal bearing basin,and analysis on coal bodies in main coal seam of Guchengzi Formation,the depositional environment of this kind of coal seam has been interpreted,together with the analysis on sedimentary features of root and trunk fossils within the coal seam. It shows that the basins depositional dynamic process was controlled by the lake level,tectonic subsidence and provenance.The paleoclimate influence the lake level changes,wave storm,function,source type and rate of sediment supply to a certain extent,even the plant type Fushun basins water depth is about 10 m at the basin edge where developed a large amount of water plants.The relative ideal water depth of depocenter may be 30～100 m. Because of syn sedimentary falt network activity,variation of water depth is in the form of sudden change in horizontal water body.Its depositional dynamic system is composed of perturbation lagging dynamic system,hypautochthonous dynamic system and allochthonous dynamic system.Allochthony depositional dynamics acts as the leading factor in lakeside(10 m) slope (10～30 m) basin(30 m) environment.Because Fushun basin is in high speed subsidence with low speed sediment supply during Guchengzi Period,the intraclastic deposition is active,therefore,the extremely thick coal seam can be used as an example of deeper water coal accumulation mode.
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