| Based on the analysis of the drill, logging data and the summary of predecessors’achievements, It indicates that Dayangshu basin is a Mesozoic fault basin. The deep fault of the basin boundary be control the formation and development of the basin. North North East to North-East normal faults for the master fault in basin, with a high angle, big fault distance, control characteristics of the basin boundary. They are nearly east-west trending normal faults cutting, staggered, Formed the tectonic framework characteristic be depression area and uplift area from north to south.Dayangshu basin is a Mesozoic fault basin that is built on the Paleozoic in acidic intrusive rocks and metamorphic basement. With the characteristics of intermittent eruptions volcanoes-type basin, forming eruption (early Cretaceous Longjiang formation)—deposition (early Cretaceous Jiufengshan formation)once more eruption (early Cretaceous Ganhe formation) of the cycle Structure of volcanic eruption-deposit. The analysis thought is the strata of research region ought to be divide into Proterozoic, Permian, Longjiang formation, Jiufengshan formation, Ganhe formation of lower Cretaceous, Tertiary and Quaternary from old to new in Dayangshu basin. The main coal-bearing stratum is Jiufengshan formation, It also is the main analysis stratum. The structure of Jiufengshan formation from bottom to top may be divided into several different deposits phase:coarse clastic rock filled deposit in the early fault phase, the transgressive system tract in partial coal deposition phase, deep lake mudstone overlap phase of lakes facie and the regressive system tract of overall shrinking basin at main in coal deposition phase. It can be distinguish from are alluvion fan, fan delta, lakes and lakeside swamp. Tectonic and palaeo-geography are the main factor of control coal accumulation in Dayangshu basin. Analysis concluded that Jiufengshan formation period has two stages of coal formation and three kinds of coal accumulation models.The main innovation of the article is volcanic activity analysis with intermediate stage of Jiufengshan formation in the research area. According to the middle area of Dayangshu basin drill geological data, logging data, It is visible that the partial drill hole are contain the overflow basalt in Jiufengshan formation, It is determined that the existence of multiple small-scale volcanic activity before the coal deposition in the later Jiufengshan formation. And carry on the relevant analysis to the overflow basalt in the middle of the Jiufengshan formation and overlying coal deposition, Reveal the distribution characteristics of basalt have the relevance with coal deposition has a role in indicating the range of occurrence. Explain their reason for the overflow basalt in the middle of the Jiufengshan formation reduce the accommodation space and the edge of the slope of the basin, and reform the transformation of landform has played an important role with Coal accumulation in later the overlying strata. The distribution characteristics of the overflow basalt in the middle of the Jiufengshan formation are reflected the paleo-geographic environment at that time, and paleo-geographic environment have directly control the distribution of the overlying coal seams. Therefore, volcanic activity analysis with intermediate stage of Jiufengshan formation can predict the paleo-geographic environment and the distribution of the coal seam in overlying strata. The performance was basalt rapidly disappearing reflect the paleo-geographic environment strata slope is big, stratigraphic facies change fast, is not conducive to the upper coal development. And when basalt stable reflect the paleo-geographic environment strata slope is flat, is conducive to the upper coal development... |
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