羌塘盆地晚三叠世含煤岩系沉积体系与层序地层学特征

利用地层剖面岩相组合、沉积构造序列,结合粒度分布特征等分析了研究区晚三叠世沉积体系与沉积环境演化,建立了含煤岩系层序地层格架,讨论了含煤岩系层序地层学特征和煤层在层序格架下的位置、聚煤特征及空间分布规律。研究表明,晚三叠世含煤岩系沉积体系有浅海碎屑陆棚沉积体系、滨岸沉积体系及三角洲沉积体系,其中三角洲沉积体系的三角洲平原是区内最主要的成煤地带,煤层均位于SQ1层序的高位体系域内,分布于盆地中央隆起带内,向南、北两侧,由于水体加深而脱离沼泽沉积环境,不利于煤层的形成。中央隆起带是羌塘盆地今后重要的找煤方向。

Late Triassic Coal-bearing Rock Series Depositional System and Sequence Stratigraphic Features in Qiangtang Basin

Based on stratigraphic section lithofacies combinations,depositional structure sequences,combined with grain-size distribution features,analyzed study area late Triassic depositional system and sedimentary environment evolution;established coal-bearing rock series stratigraphic framework;discussed coal-bearing rock series sequence stratigraphic features and location of coal seams in the sequence framework,coal-accumulation features and spatial distribution pattern.The study has demonstrated that in the late Triassic coal-bearing rock series shallow sea clastic shelf,perezone and delta depositional systems,the deltaic plain in delta depositional system is the main coal-forming zone in the area.Coal seams were all deposited in the high stand systems tract of the SQ1,and distributed in the central mole track of the basin;toward both south and north sides,since the deepening of water and apart from peat bog sedimentary environment,adverse to coal forming.Thus the central mole track is the major coal looking orientation in the Qiangtang Basin