The Study On Coal Bearing Strata Of Lower Cretaceous In Yangcaogou Basin Of Jilin Province And The Accumulation Rules Of Coal

Yangcaogou basin is one of a series of coal bearing fault-seg basin in NE direction,developing from late Jurassic to early Cretaceous of Mesozoic in the eastern margin of Songliao basin,it is in Changchun—Yingcheng fault-seg region. By means of studying on the coal bearing strata of lower cretaceous in Yangcaogou basin and the accumulation laws of coal,all of them have significant theory and actual sense to relieve the coal lacking in Changchun region and Jilin province,to prospect,to forecast and to look for new coal field and coal bearing place in the Songliao basin east margin,to tap the latent power in the mining district of Yangcaogou,to achieve the high production, high efficiency and safe production mine.Based on sufficiently utilized on predecessors' achievements and data,by means of analying the geolgoical backdrop that Yangcaogou basin took palce,I known that the evolution of Yangcaogou coal basin was restricted by regional geological backdrop of east margin of Songliao basin, and controlled by faults in NE,NNE directions. With volcanic activities, the shape of Yangcaogou basin in plane is a long belt,the section shape is like a bowl. The incoalation type is fault-seg type. The damage in later stage took shape remains edge of south-east. I think that strata of Yangcaogou basin ought to be divide into Huoshiling formation of upper Jurassic,Shahezi formation, Yingcheng formation, Dayangcaogou formation, Quantou formation of lower Cretaceous,and Pleistocene of Quaternary. Chief coal beds that can be mined are in Dayangcaogou formation.Frequency volcanic activity accompanied the forming of Yangcaogou basin from start to end. It is an important feature of Yangcaogou basin. Yangcaogou basin underwent four times cycles of volcanic eruption-deposit in process while it formed and developed from upper Jurassic to lower Cretaceous: i.e. neutral volcanic eruption cycle of Houshiling formation, the neutral-acid volcanic eruption cycle of Yingcheng formation, basic volcanic eruption cycle of Dayangcaogou formation, and the basic volcanic eruption cycle of Quantou formation. By means of observation, microscope appraisal and test,we find that main rock types of Yangcaogou coal bearing basin are the conglomerate, sandstone, deposit tuff, argillaceous shale and volcanic rock. Basis on macroscopic deposit feature, sections of deposit facies, drillhole and rock forming marker, types of facies that can be distinguish from are alluvion fan ,fan delta, lakes and swamp. In them alluvion fan and fan delta most develop. Structure of Dayangcaogou formation From bottom to top may be divided into four different deposits phase: filled deposit phase(K1y2,K1dy1),main incoalation phase(K1dy2-1,K1dy2-2), overlap phase of lakes facies(K1dy2-3,K1dy2-4,K1dy2-5) and shrink phase(Kldy2-6). By means of analyses, it is known that,before ⅡThe coal series formation,Guangning and Yangcaogou two districts are separately isolated minitype segs. Yangcaogou district initial is priority to deposit of alluvion fan,the deposit of Guangning district is rather little. Till K1dy1 later stage －K1dy2-1 stage,two districts are wholly with deposit of alluvion fan —fan delta —brink lake in main. At the same time some intermittence swamp deposits appeared. When K1dy2-2,The basin became the all and the one, the great area of lakeside became marsh. chief coal beds can be mined formed. Till K1dy2-3 to K1dy2-5 ,The whole basin dropped. water invaded, a suit of deposit of shallow lake - deep lake fcies appeared. During K1dy2-6 ,the basin started raising, a suit of deposit of shallow lake brink facies, delta facies, river facies,alluvion fan facies. With further raising of the basin,underwent disintegration. Thereby create unconformity contact with superstrata. Finished fill action of Dayangcaogou basin. The composition of this four phases,represented full process of happening, development and wither away of the basin.The coal beds of Yangcaogou coal baring basin are in Dayangcaogou formation of lower cret...