The Ordos Basin And The Energy And Mineral Related Geochemical Study

Ordos Basin is one of the greatest Energy Mineral Diposits Gathering basins in China. Different epoch and most kinds of Energy Mineral Diposits are concurrent in this one basin, so Ordos Basin becomes a rich large-scale Experimental Site for geologic research activity. Geochemical analysis of the Energy Minerals and the relative fluid research in Ordos Basin becomes very important, not only for enhancing reservoir formation and mineralization theory, but for finding new Energy Minerals base and enlarging energy margin.This thesis depends on the National 973 Projects— "The formational mechanism, accumulation and distributionPatterns for multi-energy mineral deposits coexisting in the same basin(2003CB214605)" , in which, the geochemical characters of Energy Mineral Diposits has been analyzed. It is said:1, Both of the nature of the geochemical field of surface elements and the feature of the deep structure suggest that there are deep fluid action and energy mineral reservoir formation and mineralization in Ordosie Basin. There is close relationship between the geochemical division and the energy mineral distribution. The intracrustal high conductive layer and the deep great fractures supply the basic condition for deep fluid action in this basin. The nature of the tectogenesis after Mesozoic era and the geochemical field of surface elements suggests that the deep fluid is still moving. The distribution of the Multi-energy Mineral Diposits and the geochemical field is controlled by the basement faults in the basin. In some way, the nature of the geochemical field shows that the deep fluid took part in the energy mineral reservoir formation and mineralization.2, In zones with the strong tectonic activity and basement faults, the elements combination of petroleum is complex and the material from deep resource can be found in which. The character of elements geochemical and carbon isotope all show that there are deep fluid components in some Energy Minerals. The material source of the water accompanying with petroleum reservoir is complex, and which with multi-sources. The character of elements geochemical shows that the uranium of Dongsheng uran ore comes from the upper crust, the greyish-green gritstone and hoary kaolinised argillaceous siltstone is important for the formation of uranium deposits,and the grey gritstone is great potential to surveying uranium deposits . Which also shows that the trace elements in Heidaigou coal and its dirt are from the upper crust.3, The geochemistry of Chloroform bitumen "A" accompanying with Energy Mineral Deposits has been studied, and the result said: elements combination of the asphalt is same as the one of petroleum, and the asphalt and the petroleum are with same sourcesin some way, but the deep fluid component in asphalt is relatively high, and even higher than the evolution degree of petroleum undergone in anaphase. Most of the asphalt in Dongsheng sandstone with uranium belongs to foreign fluid, whose source is different from the one of Dongsheng sandstone with uranium, and all of these show that the uranium resource is not this kind of fluid like asphalt. The difference in source and origin of the associated asphalt in energy mineral diposits suggests that the multistage action fluid in Ordosie Basin is the outcome of different stage evolution. The feature of laser Raman spectroscopy hints: The reducibility gas such as C2H2. C2H6, CH?, C2H4 can be found in chloroform asphalt extensively, whose content is growth and decline with the one of oxygenization gas CO2, and all of these show the feather about later reformation and redox condition for the chloroform asphalt.4> The result of Q-clustering analysis on the fluid accompanying with Energy Mineral Diposits says that the formation and the tectonic site the petroleum lying in mainly impact on its element geochemistry. There is some relation between petroleum and its associated water on origin. The petroleum in Chengjiashan coalbed maybe one kind of mixture mixed by the oil coming from the coal of Carbonic-Permian and Jurassic Yanan group. The Yanan group petroleum is with the same fluid activity character and material source as the one of Zhiluo group. Jurassic Yanan group and Zhiluo group are with the similar deposit environment and final evolving feature. The asphalt from Yanan group oil mainly affects on the activation, transportation and beneficiation of the uranium. The associated water with gas is with little dependence on the petroleum, but it correlate with the oil asphalt and the coal asphalt.5> Base on the result of geochemistry study, a set of identification of reservoir formation and mineralization for Multi-energy Mineral Diposits has been brought forward, and base on which, two possible oil-gas-coal intergrowth zones, two gas-coal intergrowth zones, one oil-coal intergrowth zone and three uranium enrichment zones are been marked out.