Research On Coal-forming Environment And Sequence Stratigraphy In Coal Measures Strata

Base on sequence stratigraphy, high-resolution sequence , sedimentary and other theories and methods, the depositional system, lithofacies palaeogeography, coal-accumulating and controlling factors of Carboniferous-Jurassic in Qinghai Province have been studied.Two group sedimentary facies, eleven sedimentary facies and many subfacies, microfacies types have been recognized and the depositional models have been stablished by macroscopical and microcosmic research methods, basing on the detailedly observation of field profile, combinated with conventional log, seismic and regional geological condition. Based on previous analysis, the coal-forming environments were systematical researched. The coal-forming patterns of alluvial fan—fan delta system, meandering river- meandering-delta, and braided-braided delta have been established.It is necessary to consider multiple factors in sequence analyses and to apply different interpretation models for different types of coal-forming environment. The coal - bearing strata of Carboniferous- Triassic is marine strata . Base on anlysis sequence boundaries and interface generation, the sequence stratigraphy framework is built up and the characteristics of the sequences are analyzed by Vail classic sequence theories and methods. The coal - bearing strata of Middle - Lower Jurassic Series is continental formation. Combined with the high resolution sequence stratigraphic theory, The formation was divided into short-term ,middle-term and long-term base-level cycle. On base of the previous analysis, the coal development pattern in sequence stratigraphic framework was analysised.Based on the comprehensive analysis of coal-forming environment, coal-forming pattern, and sequence stratigraphy, makes use of results of predecessors, the four enriched regularit ies of coal in Qinghai Province have been predicted, which include 22.05656 billion tons of coal resources in Qilian Mts, 12.07787 billion tons of coal resource in migration of north Qaidam Basin, 5.32557 billion tons of coal resource in Tanggula Mts, 0.54006 billion tons of coal resources in East Kunlun- West Qinling Mts. On the base of the study, the ten target areas have been predicted, which include the target area of Datong Mining Area outside, the target area of Ningchan Mining Area outside, the target area of Juhugeng Mining Area outside, the target area of Tanjian Mts Mining Area outside, the target area of Eastern of Yuqia , the target area of Yematan—Junmuchang, the target area of Jiezha, the target area of Baocaogou—gasong Mts, the target area of Kaixinling, and the target area of Zhasu—daha.