祁连山东段宝积山—红会煤盆地沉积环境与聚煤规律

Sedimentary Environments and Coal Accumulation of the Baojishan-Honghui Basin,Eastern Qilian Mountains

位于祁连山东段的宝积山—红会盆地是一个典型的侏罗纪沉积盆地,侏罗纪煤系由冲积扇沉积体系,经过河流、湖泊三角洲沉积体系向湖泊沉积体系过渡的沉积序列组成,并充填于印支运动后的裂陷盆地内。盆地活动断裂边界的内侧发育冲积扇裙,向着不活动边缘的另一侧,逐渐被河流沉积体系和湿地沼泽系统替代。扇前湿地是主要聚煤场所,形成的煤层层数少,主煤层厚度变化大,煤体呈简单指状。扇前湿地泥炭沼泽具有富滋养或低位性质,形成的煤层灰分产率高,硫含量有明显的分带性,其变化取决于泥炭沼泽与冲积扇体的相应空间位置。

Baojishan-Honghui Basin is a typical small- scale Jurassic coal-forming basin located in the east part of the Qilianshan Mountains. The sequence of the Lower to Middle Jurassic strata is deposited in the sedimentary cycle from the alluvial fan and/or fluvial, to lake delta and lacustrine depositional systems, and fill in the half graben type basin formed by extension of post-Indosinian Movement . The complex of the alluvial fan-bodies are developed in the vicinity of active fault, from where to another side of non-active sedimentary boundary, there are gradually replaced by fluvial and wetland swamp system. Peat accumulated directly on the wetland in front of alluvial fans, in where the main coal seams with the features of large thickness and simple finger-like shape are formed. There are eutrophic or low moor peats in the front swamp of alluvial fans, so that the coal beds with high ash content and sulfur content zonation are formed, as the case may be the space relationship between peat swamps and alluvial fan bodies.