北祁连西段石炭-二叠纪含煤地层沉积模式研究

Study on Depositional Model of Permo-Carboniferous Coal-bearing Strata in West Section of Northern Qilian Mountains

为揭示北祁连西段石炭-二叠纪含煤地层沉积模式及聚煤规律,采用野外露头观察、钻孔岩心描述、测井分析及综合作图等方法对其进行研究,识别出太原组砂砾岩段发育河流相,羊虎沟组和太原组含煤段发育潟湖相、潮坪相、碳酸盐台地及沼泽相;沉积环境经历了陆源碎屑体系发育、泥炭沼泽体系发育、碳酸盐体系发育、陆源碎屑体系复活4个阶段。研究表明:成煤期主要发育潟湖—潮坪沉积模式,厚煤层主要形成于潟湖泥炭沼泽环境,在潮坪成煤环境煤层较薄或不发育;太原组含煤段发育M5、M6和M3、M4两套主采煤组,聚煤中心分布在东部的日旭-青羊沟-阿力克一带和西部的五林沟-野马泉滩一带。

In order to reveal the depositional mode and coal accumulation law of Permo-Carboniferous coal-bearing strata in western part of the Northern Qilian Mountains,based on outcrop section,borehole cores,logging analysis and comprehensive mapping method,fluvial fa-cies was recognized in the sandy conglomerate member of the Taiyuan Formation,and four types of facies including lagoon facies,tidal flat facies,carbonate platform and swamp facies were recognized in the Yanghugon Formation and the coal-bearing member of the Taiyuan For-mation.The sedimentary environments had experienced four stages,including terrigenous clastic system,peat swamp system,carbonate sys-tem and revival of terrigenous clastic system.The results showed that the lagoon-tidal flat coal-forming mode was proposed for the coal ac-cumulation in the study area.The thick coal seam was mainly formed in the lagoon peat swamp,while the coal seam formed in the tidal flat coal-forming environment was thinner.The coal-accumulation center of the primary mineable coal groups of M5,M6 and M3,M4 which were formed in the coal-bearing member of Taiyuan Formation were mainly distributed in the area of the eastern Rixu-Qing Yang Gou-A-Like belt and the western Wulingou-Yemaquantan belt.