| Title | Radioactive Geochemical Characteristics of a Certain Geothermal Field In Jizhong Depression, N-China |
|---|---|
| Authors | Gongxin Chen, Zhanxue Sun, Hang Su, Jinhui Liu, Angdong Wang, Dexuan Kong, Yong Fan |
| Year | 2023 |
| Conference | World Geothermal Congress |
| Keywords | cgx95121@163.com |
| Abstract | As we all known, geochemical exploration has been widely used in geothermal resource exploration . In recent study, it was found a good potential resource of thermal water for exploration from Jizhong Depression North-east China. In this paper, both of soil geochemical and rock radioactive geochemical characteristics have been studied in order to provide useful information for the deep geothermal resource exploration in this region. Soil elements, such as As, Bi, Sb, Hg, Be, As, Li, Cu, Zn, Mn, Co, Cs, Sc, Ni, Pb, Rb, Sn, Mo and W, were significantly self-correlated which were related to thermal fluids up-flowing . These elements were enriched to a certain extend in some area, in Niutuozhen Uplift in,south of study area. They were higher values than those from Daxing Uplift. Their distribution has a good related to the distribution of deeper and larger faults, such as Daxing and Niudong Fault. High 210Po concentration from soil and high radon from thermal water were occurred in Niutuozhen area in the south area. This result showed that the deep hydrothermal fluids flew up along the regional faults that could be indicated by these elements in the soil. Rock property study obtained the thermal conductivity of both limestone and dolomite, with average values of 3.92W/mK and 5.75W/mK, respectively. These values were higher than those of other type rocks, while radiogenic heat flux was lower than others rocks, with average values of 0.75 μW/m3 and 0.19 μW/m3. This indicated that these two type rocks could contribute amounts of conduct heat flow from the depth to form heat reservoir. The overburden were mud-stone and conglomerate with huge thickness, low water permeability, and low thermal conductivity (2.35W/mK and 3.24W/mK average). Those properties help to keep heat escaping from thermal reservoir. The thermal conductivity of gneiss rock which found in the depth was 2.59W/mK in average, which was lower than those of other rocks, but the radiogenic heat flux , with 1.26μW/m3 average, was higher than that of other rocks. According to radioactive geochemical characteristics, the percentage of heat flow from crust was calculated ranging from 36.9% to 48.4%, which was less than 50%. This indicated that lithographer thermal structure in these region has a typical hot mantle cold crust characteristics.Heat were from mantle through conduction was greater than from crustal radiogenic heat. Soil elements, such as As, Bi, Sb, Hg, Be, As, Li, Cu, Zn, Mn, Co, Cs, Sc, Ni, Pb, Rb, Sn, Mo and W, are significantly correlated with each other. They were enriched to a certain extend in some area. In our study region, these elements from Niutuozhen Uplift in the south of the study area are higher than those from Daxing Uplift. Their distribution has a good related to the distribution of deep and large faults, such as Daxing Fault and Niudong Fault. The high 210Po from soil and high radon from thermal water were occurred in Niutuozhen area in the south. This indicated that those elements in the soil had a certain relationship with the deep hydrothermal fluids flowing up along the deep and large faults. Rock property study showed that the thermal conductivity of both limestone and dolomite, with an average value of 3.92W/mK and 5.75W/mK respectively, were higher than those of other type rocks, while the low radioactive heat generation of both two rocks were lower, with an average value of 0.75μW/m3 and 0.19μW/m3, in the study area. These indicated that these two type rocks could be benefit to conduct heat flow from the depth, which give a good contribute to form heat reservoir. The overburden were mud-stone and conglomerate with huge thickness, good water permeability, and with low thermal conductivity (2.35W/mK and 3.24W/mK average). Those properties help the heat to be stored in thermal reservoir. The thermal conductivity of deep gneiss with 2.59W/mK in average t is lower than that of other rocks, but the radioactive heat generation of this rock, with 1.26μW/m3 average, is higher than that of others from this region. According to radioactive geochemical characteristics, the percentage of heat flow from crust was calculated ranging from 36.9% to 48.4%, as well as the those from mantle, which is less than 50%. This indicated that lithographer thermal structure in these region has a typical hot mantle cold crust characteristics and heat are mainly from mantle through heat conduction. |