新疆北部侏罗纪巨厚煤层的煤岩特征与煤相演替

Thick coal seam occurred in Jurassic, Xinjiang. They have huge reserve and high quality. Single coal seam whose thickness is more than 60 m has been developed in Turpan-Hami basin and the eastern part of the Junggar basin coalfield. Because of its huge economic value and favorable mining conditions, the thick coal seam has been paid much attention. Domestic and foreign scholars had different perceptions about weather Xinjiang Jurassic coal rocks have rich inertinite and poor exinite or not. The change of coal maceral caused by coal-derived hydrocarbon and strong weathering had been ignored in previous research about coal petrography, which finally influences coal facies confirming. This project aims to quantitatively recover the original coal maceral, accurately and quantitatively evaluate the content of the maceral by identifying macerals during the process of the coalification of low-rank coal and the coal weathering. The coal facies and its vertical succession of thick coal seam will be identified by various methods, such as parameters of coal facies , coal nodule , sporopollen and geochemistry. This will accurately reveal the original environment of Xinjiang Jurassic coal and coal-forming material. A set of system method to comprehensively evaluate Jurassic coal facies is established, which will not only enrich geological theory of Chinese coalfield about the northwest Jurassic coal, but also provide a scientific basis to the quantitative evaluation of Xinjiang Jurassic coal derived oil.

新疆侏罗纪煤储量巨大且煤质优良，在吐哈盆地、准东煤田等地发育有单层厚度超过60m以上的巨厚煤层，巨厚煤层由于其巨大的经济价值和有利的开采条件而倍受重视。但国内外学者对新疆侏罗纪煤中煤岩富惰与贫壳的认识不一致，前人煤相的研究中也忽视了煤成烃及后期强烈的风化改造对煤中显微组分的影响，最终影响到了煤相的揭示。项目拟开展低阶煤化过程显微组分鉴定实验、煤风化过程显微组分鉴定实验定量恢复原始的煤岩显微组分，精确定量评价显微组分的含量，通过煤相指数结合煤核、孢粉与地球化学等多种手段分析确定巨厚煤层的煤相,研究煤岩和煤相在垂向上的演替。从而准确反映新疆侏罗纪原始的成煤环境和成煤物质，建立一套综合评价新疆侏罗纪煤相的系统方法，这不仅可以丰富我国煤田地质理论关于西北侏罗纪煤的认识，而且可以为新疆侏罗纪煤成油等的定量评价提供科学的依据。

新疆北部地区侏罗纪煤储量巨大，且煤的质量优良，多为低灰、低硫煤，国内外学者对新疆北部侏罗纪巨厚煤层煤相方面研究较少。课题组对新疆准东煤田五彩湾矿区以及吐哈盆地沙尔湖矿区侏罗纪巨厚煤层进行煤岩鉴定、工业分析，其中着重研究准东煤田的显微煤岩组分分布情况。利用低阶煤煤化过程中显微组分鉴定分析、风化过程中显微组分鉴定分析、光学显微镜、显微光度计结合透射电子显微镜（TEM）方法确定煤岩组分含量、煤核鉴定、孢粉鉴定等方法对新疆北部侏罗纪巨厚煤层进行煤相类型划分，并对煤相在平面上的展布特征和垂向上的演替规律进行总结。研究结果显示研究区煤层宏观煤岩类型为半暗煤及暗煤层，矿物含量高，古气候属于热带-亚热带气候；煤相主要划分为以森林沼泽相为主，成煤沼泽由自下而上先后经历浅覆水沼泽-深覆水沼泽-潮湿沼泽-干燥沼泽的过程。通过开展实验及研究，基本摸清了新疆北部煤田侏罗纪巨厚煤层的煤岩特征与煤相演替规律。