Characteristics Of Gas Geochemistry In Western Margin Fault Zone Of Ordos Basin

The natural active fault zone is the weak zone of the earth.It is an important place for degassing in the earth because of the development of fractures and the relatively smooth migration of fluids.There are many active faults in the Chinese mainland,so the gas released from the active fault zone and its influence on the atmospheric environment cannot be ignored.The Western margin fault zone of Ordos Basin is a middle-strong seismic zone in north China,which is rich in underground mineral resources,well-developed deep and large faults and densely populated.The investigation and study of the gas release from the fault zone in the western margin of the Ordos Basin and its impact on the atmospheric environment can not only provide important scientific basis for the formulation of Environmental Planning in the western margin of the Ordos Basin,it is of great scientific significance to enhance the theoretical basis and technical level of the investigation and study of gas release from active fault zones and to promote the investigation and study of gas release from active fault zones in Chinese mainland.In this paper,the observational data of gas emission flux from the main active fault zone in the western margin of Ordos are obtained by means of field cross-fault flow observation.By means of calculation and analysis,the influence of gas release on regional environment is evaluated,and the related research results of tectonic geology,Petrology,geophysics,etc.,the spatial variation characteristics of gas release from active fault zone are discussed in this paper.The main results are as follows:?1?Through measuring the contents and fluxes of Rn,Hg and CO₂ in different segments of the main fault zone in the western margin of Ordos,the concentrations of the whole basin are 0-60.09 kBq m^-3,3-81 ng m^-3 and 0.04-9.23%,respectively,the fluxes were 1.99-306.99 mBq m^-2 s^-1,0-15 ng m^-2 h^-1 and 0-37.91 g m^-2 d^-1,respectively.?2?By analyzing the profile concentration distribution curve of the fault zone and comparing the characteristics of the main active fault zone in the western margin of Ordos and the gas emission flux in the Ordos Basin,it is revealed that the active fault zone plays an important role in the degassing of the Earth Interior.?3?Through comprehensive analysis,it is analyzed that regional tectonic activity is the main controlling factor of gas release in the main active fault zone in the western margin of Ordos.Temperature,humidity,precipitation,vegetation,soil,granite,uranium,oil,gas,coal and other relatively weak impact.?4?There is no CO₂ risk in the study area,7 fault zones in the central and southern parts of the western margin fault zone are polluted by Rn to different degrees,and 6fault zones are polluted by Hg to different degrees.According to the calculation,the annual emissions of Hg and CO₂ are 11.29 g and 0.99 Mt,respectively.