Analysis Of Mesozoic Tectonic Environment In Rujigou Area

Because of the western margin of ordos basin tectonic belt locates in the important tectonic setting as well as the bright prospect of its oil, gas and coal resources, it has widely aroused energy worker's interest and attention for a long time. Rujigou area is an important area of Taixi coal producing area of our country. Taixi coal which is low ash and sulfur,while high quality anthracite is very rare in the world.This thesis is basesd on collecting the predecessor material and the researchs on this topic, taking the tectonic geology, the sequence stratigraphy and the sedimentology as the theory bases, unifing the existing foundation geological data with the newest test achievement and the related papers, and coordinating the geochemistry analysis method. It starts with formation characteristics, the rock characteristics, the deposition analysis and constructure distortion researchs,etc of the Rujigou area Mesozoic Era's. Through the analysis of typical geological phenomenon, the author of this thesis has discussed the nature of Rujigou area mesozoic tectonic setting.(1)Through comparison between Rujigou area Mesozoic Era late Triassic period-early and middle Jurassic period formation characteristics, sedimentation analysis and that of Ordos Basin and the analysis of the late Triassic period extension and early-middle Jurassic Period deposit provenance it sets forth that during the period. Rujigou area was part of the Ordos basin and the provenance originated Zhengyiguan fault;(2)Through the analysises of the indicators of the Rujigou basalt geology geochemistry, the rare earth and the trace element test material, it is determined that this basalt for within-plate tholeiite basalt formed in within-plate extension tectonic setting in the late Triassic-middle Jurassic periods. It reflectes that this period the Rujigou area is in the extension tectonic setting;(3)According to the stratum distribution rules and characteristic of the Xiao Sungshan bedding fault, and the fission diameter mark test materials, and its distortion characteristics, the author of this thesis belives that thought that the Mesozoic Era, the western ridge of Rujigou area used to be on a slope and topography slowly declines from west to east. The Xiao Sungshan bedding fault used to be gravity slip detachment struture and it has represented the extension from the east to west. At present the Rujigou area is higher in the east and lower in the west, which is the result of the reversion of this area in later time;(4)It can be concludes that, in Mesozoic Era late Triassic period-early and middle Jurassic period, Rujigou area was in east-west region tensional stress environment which was tensional fault subsidence.