Study On Sequence Stratigraphy And Coal Accumulation Law In Tuanyushan Area,Qinghai Province

Tuanyushan area is located in the north margin of Qaidam Basin and the south margin of Saishiteng Mountains, and affiliated to Dachaidan area of Qinghai Province. It includes the northern Tuanyushan, Kunyuan open coalmine, central Tuanyushan and Jielvsu, which is one of the key coal producing areas in northern Qaidam basin. It is of great theoretical and practical significance to guide the exploration of peripheral coal resources and to improve the geological exploration effect through studying the coal accumulating law by using available data.The deposition system, sequence stratigraphic framework of the Jurassic, the characteristics and evolution of lithofacies palaeogeography, coal accumulation law and further direction for coal are analyzed, based on the coal exploration geological achievements and data of Tuanyushan area.Tuanyushan area is generally a south west dipping monocline,affected by the late Himalaya orogeny, formed imbricate thrust nappe tectonic system. The regional faults in the study area is NWW-WEE extension and consistent with trend of the strata. The coal bearing strata are the Middle Jurassic Dameigou group and the Shimengou group. There are 7 seams of coal in the area, such as 5 seams of coal in the Shimengou group, and 2 seams in the Dameigou group.The study area is a continental sedimentary system, which the main deposition facies are braided river, braided river delta and lake. Based on the study of sequence stratigraphy, the Jurassic in the area can be divided into 4 third-order sequences (S?1-S?4). The coal seam is mainly developed in the braided river alluvial plain of the Middle Jurassic Dameigou formation sequence of SIII1 sedimentary period. There are less seams developed in the Middle Jurassic Shimengou formation sequenceS?2 and sequence S?3 braided river delta.The coal accumulation is mainly controlled by paleoclimate, basement subsidence,sedimentary environment and base level change. It is predicted that the southern margin of Tuanyushan is a favorable area of coal and sequence S?1- sequence S?2 is the main coal seam to be found.