鄂尔多斯盆地西南缘中侏罗世延安组特厚煤层成因机制研究

As we know, coal seam was the product of peat paleo-bog development and evolution, and many geological information was recorded during the coal-forming period, such as sedimentary environment, accommodation space changes, palaeoclimate evolution, etc. This research will select Binchang mineral district on southwestern of Ordos Basin as the region of interest, and analyze the anthracology, geochemistry, sequence stratigraphy and lithofacies palaeogeography features of special-thick coal seams of Yan’an Formation in Binchang mineral district, in order to study the characteristics of different types of inner hiatal surface (inorganic parting, “exposure” hiatal surface or oxidized parting, “drowning” hiatal surface or degradative non-oxidized organic parting), continuous genetic unit, coal facie pattern, sequence stratigraphic framework and lithofacies paleogeographic evolution. At the same time, the response relationship between different types of hiatal surface and various logging information will be analyzed, in order to put forward the logging information recognition method. In order to dig out the geological information of coal facies evolution, accommodation space dynamic changes and palaeoclimate evolution implied within the special-thick coal seam, the coal macerals, stable carbon isotope, trace element and log information of special-thick coal seam will be analyzed, and the control factors and driving force mechanism that peat paleo-bog can develop and superimpose in same area will be unravelled. In view of the above, this project presents the coupling relationship between different types of hiatal surfaces and the continuous genetic units, in order to fundamentally elaborate the genetic mechanism of special-thick coal seams.

煤层是泥炭沼泽发育与演化的产物，其中记录了聚煤期的沉积环境、可容空间变化、古气候演化等地质信息。该项目拟对鄂尔多斯盆地西南缘彬长矿区延安组特厚煤层的煤岩学、地球化学、层序地层学和岩相古地理学等特征进行分析，研究特厚煤层中不同类型间断面（非有机质段、暴露间断面/氧化界面、淹没间断面/降解-非氧化界面）、连续成因单元、成煤古环境、层序地层格架及岩相古地理演化等特征；同时，系统分析特厚煤层中各类间断面与多种测井信息之间的响应关系，建立各类间断面的测井信息判识方法；研究特厚煤层中煤岩显微组分、稳定碳同位素、微量元素和测井信息的特征，挖掘其中蕴含的可容空间动态变化、古气候演化等信息，剖析特厚煤层聚煤期泥炭沼泽在同一地区、多期发育与叠加的控制因素和驱动力机制。进而提出特厚煤层中不同类型间断面和连续成因单元发育的耦合关系，从本质上阐明特厚煤层复合体的成因机制。

煤层是泥炭沼泽发育与演化的产物，其中记录了聚煤期的沉积环境、沉积旋回、生产力条件、古气候特征及其演化等地质信息。本课题以鄂尔多斯盆地西南缘彬长矿区延安组一段特厚煤层为研究对象，分析了特厚煤层的宏观沉积特征，识别了特厚煤层内部的沉积间断面，建立了沉积间断面的综合判识方法；分析了特厚煤层内的煤相类型与垂向演化；建立了特厚煤层内部高精度的沉积旋回，分析了成煤期的古气候特征与演化等，建立了古气候旋回的综合判识方法，并查明了其驱动力机制；研究了特厚煤层中不同类型间断面和连续成因单元连续发育的耦合关系，建立了坳陷盆地特厚煤层典型的成因模式，从解释了坳陷盆地特厚煤层复合体的成因机制。此外，还初步研究了煤系某些共伴生矿产的聚集规律。本研究进一步完善和丰富了煤地质学基础理论，同时为煤系多矿产精细勘探提供了一定的理论支持。