含煤岩系层序地层学研究进展

Developments of coal measures sequence stratigraphy

层序地层学是分析聚煤规律的一种有效方法。层序地层学应用于含煤地层的分析始于20世纪90年代,Diessel最先在经典层序地层格架中建立了煤层的聚集模式;之后,Bochacs和Stuer通过讨论可容纳空间的变化速率和泥炭聚集速率之间比值的变化,具体分析了不同可容纳空间的煤层厚度、连续性及形态。通过对层序地层中煤层发育和分布的研究,多数煤田地质学家们认为,厚煤层主要发育于低位体系域晚期至海侵体系域早期及海侵体系域晚期至高位体系域早期。由于巨厚煤层往往是许多次级层序及界面的复合体,因此巨厚煤层不能简单地作为成因层序地层的界面,但可以通过煤岩学和地球化学方面的指标对其进行精细划分确定。我国煤田地质学家通过对国内海相煤层的研究,提出了海侵事件聚煤和海相层滞后时段聚煤等观点,从而大大促进了含煤岩系层序地层学的发展。

It is beneficial for exploitation and exploration of coal resources and resources relating to coal to analyze developing strata and distribution of coal seam in sequence stratigraphy.The time that sequence stratigraphy began to use in coal strata was 90＇s of last century,Diessel firstly established coal accumulation model in classical sequence stratigraphy framework,then Bochacs and Stuer discussed the change of ratio of accommodation rate/peat production rate and concretely analyzed thickness,continuity,configuration of coal seam in different accommodation.Based on studied development and distribution of coal seam in sequence stratigraphy,most coal geologists think that thick coal seams were mostly developed during late low stand-early transgression and late transgression-early high stand periods.Extremely thick coal seam is composed of many para-sequence and interface of para-sequence,so we can not easily believe extremely thick coal seam is interface of genetic stratigraphy,but we can use index of coal petrology and geochemistry to finely divide extremely thick coal seam and to confirm interface of genetic stratigraphy.In China,coal geologists studied paralic coal seam and raised ideas of coal formation in the transgressive event and coal accumulation during a lag time of marine limestone beds,and that let idea of coal accumulation in sequence stratigraphy to develop.