The Forming Conditions And Genentic Model Of Medium And Low Temperature Convection Geothermal Field In Chifeng-Chaoyang Area

Geothermy is a basic nature of the earth and a high quality energy. Studing the distribution features and forming geological conditions of the geothermy, there are important theoretical significance for development of geosciences and important practical significance for prospecting and exploitation of geothermal resources.Application of low-medium temperature geothermal field of convection type principle, hydrogeology and tectonics theory, and using conceptual model of low-medium temperature geothermal system of convection type invested by Dr.White coming from the United States for basic idea to analyze problems. On the basis of analyzing their regional and geothermal geological characteristics of three typical geothermal field, the main formation conditions of low-medium temperature geothermal field and convection type and geological process between different geological conditions forming geothermy were systematically discussed, and control function of geological structure for forming low-medium temperature geothermal field of convection type were detailed study. Main results have been gained as follows:There are follow conditions forming low-medium temperature geothermal field of convection type:for guarantee hydraulic pressure of groundwater flow, recharge area must have the higher topography than geothermal field topography; the bedrocks growing large size and well hydraulic conductivity fissure system are bare in recharge area, and the major fault with the catchment function extends to geothermal field; the water insulation fault having the function that forces underground hot water upward is a boundary of fissure system; the water transmitting fault fracture zone closing to water insulation fault is thermal reservoir; the mixing intensity of shallow cold water and whether forming hot springs (underground hot water discharge to the surface) are decided by the developmental degrees of geothermal field and Quaternary.In present tectonic stress field, the East West or North East East tensile or tensor-shear faults have water transmitting function; but South North or North North West compressive or compressor-shear faults have water insulating function.The water chemical components of geothermal field depend on surrounding rock types and water-rock interaction, in which underground hot water run. The water are SO4—Na type or SO4·HCO3—Na type of geothermal field in research area, this relating to sodium rich mineral (main feldspar) of magmatic and metamorphic rocks run by underground water, and sulfide mineralization formed by volcanic-hydrothermal activity in Mesozoic, and surrounding rock leaching in process of underground water circulation. The granites have high Rn content in Reshuitang, Aohan, and the Rn content of Reshuitang geothermal field is obviously higher than Rn content of other geothermal field.Based on the above research, the local genetic model of low-medium temperature geothermal field of convection type was complete in Chifeng-Chaoyang area. Using the analogy-similar theory, Louzidian geothermal field prospect area was delimitated.