摘要：

煤相即煤的沉积相,是指煤的原始成因类型,取决于古泥炭沼泽的类型。煤相研究经过70多年的发展,取得了丰富的成果,结构保存指数(TPI)、凝胶化指数(GI)、地下水流动指数(GWI)、植被指数(Ⅵ)等煤相成因参数被先后提出。Diessel使用TPI-GI图解划分出了干燥森林沼泽、潮湿森林沼泽、草本沼泽和草木混生沼泽等煤相类型。中国主要聚煤期的煤相特征表现为,华北石炭—二叠纪煤以过渡沼泽—潮湿森林沼泽为主,华南晚二叠世煤以过渡沼泽相为主,北方的早—中侏罗世煤优势煤相为潮湿森林沼泽—干燥森林沼泽相,东北早白垩世煤以潮湿森林沼泽相为主。这些特征说明不同聚煤期的成煤沼泽类型、成煤植物和古气候条件等具有明显差异。随着深部煤层气和煤系关键金属等研究的深入,煤相研究在这些资源勘探中的应用重新获得了关注。不同沼泽形成的煤层在煤岩煤质条件上具有明显差异,因此可以将煤相分析应用于煤生烃能力评价、煤储集层物性分析和煤系共生矿物预测。近年来,随着对含煤岩系沉积环境、沼泽演化和古野火事件研究的不断深入,已有的各类煤相参数作为含煤岩系及煤层沉积环境指标的合理性受到了一定质疑,煤相参数的内涵及使用仍需进一步完善。为了煤相研究的持续发展,今后需推动煤相分析基础理论的研究,尤其是显微组分成因和现代泥炭沼泽环境的研究,并需要加强煤相分析在实际生产工作中的应用。

关键词: 煤相, 显微煤岩组分, 聚煤古地理, 沼泽环境, 煤相参数

Abstract:

Coal facies,referring to the sedimentary facies of coal,denote the original genetic type of coal,which is determined by the type of ancient peat swamp. After more than 70 years of development,coal facies research has achieved significant progress,with successive establishment of genetic parameters such as the Tissue Preservation Index(TPI),Gelification Index(GI),Groundwater Influence Index(GWI),and Vegetation Index(Ⅵ). Diessel classified coal facies types into dry forest swamp,wet forest swamp,marsh,and fen,using TPI-GI discrimination diagram. Chinese scholars have summarized the coal facies characteristics of major coal-accumulating periods in China: the Carboniferous-Permian coals in the North China coal-accumulating area are dominated by transition marsh-wet forest swamp facies;the Late Permian coals in the South China coal-accumulating area are mainly composed of transition marsh facies;the Early-Middle Jurassic coals in the Northwest China coal-accumulating area are characterized by the dominance of wet forest swamp-dry forest swamp facies;and the Early Cretaceous coals in the Northeast China coal-accumulating area are dominated by wet forest swamp facies. These characteristics reflect that significant differences exist in the types of coal-forming swamps,coal-forming plants,and paleoclimatic conditions across different coal-accumulating periods. With the discovery of unconventional resources such as deep coalbed methane and critical metals in coal-bearing series,the application of coal facies in the development of these resources has regained attention. Coal formed in different mires exhibit inherent differences in coal petrological and quality characteristics,and thus,the coal facies analysis can be applied to the evaluation of coal hydrocarbon generation potential,reservoir physical property analysis,and prediction of coal-associated resources. In recent years,with the deepening research on the sedimentary environment of coal-bearing series,mire evolution,and paleowildfire events,the rationality of using coal facies parameters such as TPI and GI as indicators for the sedimentary environment of coal-bearing series and coal has been questioned to a certain extent. The rationalization and standardized use of coal facies parameters urgently require discussion and resolution. For the sustainable development of coal facies research,future efforts should be focused on advancing the basic theories of coal facies analysis-especially the research on the genesis of macerals and modern peat mire environments and strengthening the application of coal facies analysis in practical production to better promote the utilization of mineral resources in coal-bearing series.

Key words: coal facies, macerals, coal-accumulating palaeogeography, swamp environment, coal facies index

中图分类号: 

• P618.11