豫西陕渑煤田太原组一_3煤形成环境和聚煤特征

陕渑煤田位于河南省的西部,其晚古生代煤系地层由晚石炭世太原组、早二叠世早期山西组和早二叠世晚期～晚二叠世早期石盒子群所组成。本文主要讨论太原组—3煤层形成的沉积环境和聚煤特征。—3煤沉积前的下部碎屑岩段为一套开阔型海岸碎屑潮坪体系沉积,发育潮坪以及与其共生潮道和潮沟。—3煤沉积后的灰岩段根据微相、沉积构造及其中所含的生物化石等可以确定是一套由潮间带到潮下低能带的向上变深的沉积序列。—3煤层厚度分布主要受其沉积前沉积环境的影响,其中主要潮道发育的地方以及潮坪上较低洼的地带,上覆煤层厚度小(0～0.50m),而在潮坪上其它地区,煤层则厚度大(一般大于0.50m)。—3煤硫分主要受其沉积时沉积环境和沉积后沉积环境的影响,煤层中夹有薄层混灰岩时,煤的疏分就增高。—3煤层硫分和灰分普遍高的原因是受其堆积后较深水碳酸盐沉积的影响所致。

DEPOSITIONAL ENVIRONMENTS AND COAL FORMING CHARACTERISTICS OF COAL I_3 OF TAIYUAN FORMATION IN SHANMIAN COALFIELD,WESTERN HENAN

Shanmian coalfield is located in the western Henan Province. The Late Palaeozoic coal-bearing strata in Shanmian coalfield consist of Taiyuan Formation of Late Carboniferous, Shanxi Formation of early Early Permian and Shihezi Group of late Early to early Late Permian. Mainly discussed in this paper are the depositional environments and coal-forming characteristics of coal I3 in Taiyuan Formation. The Lower Clastic Member under coal I3 is interpreted as deposits of open coast with clastic tidal flats and associated tidal channel and creeks. In the light of microfacies, sedimentary structures and fossils preserved in the limestone, the Limestone Member above coal I3 is considerd as interti-dal and low-energy subtidal zone deposits of epicontinental sea which constitute a deepening upward sequence. The thickness, lateral extent of coal I3 are mainly affected by the pre-depositional environments. Where the tidal channels and low-lying land on the tidal flats developed, the overlying coal tends to be thin ( 0-0.5m ). Conversely,the coal overlying other parts of tidal flats is thick(thicker than 0.5m). The sulphur of coal I3 is mainly affected by the contemporaneous and postdepositional environments.The coal with thin mud limestone is apparently high in sulphur. The widespred high sulphur and ash of coal I3 are resulted from the deposits of deep sea water carbonate.