Geothermal resources are a type of sustainable and green energy, which can play an important role in emission peaks and carbon neutrality. Determining the best development target area is key to resource development and geophysical methods are commonly used for this purpose. Owing to serious human and industrial interference, the microtremor survey method is often adopted for geothermal exploration in urban areas. It is a passive source method, which is non-invasive and environmentally friendly. In this method, the Rayleigh wave dispersion curve is extracted using spatial autocorrelation based on the vertical component signal at the observation station. A genetic algorithm is used to invert the dispersion curve of one survey point to obtain strata parameters such as layer thickness, S-wave velocity, and density. It provides critical parameters for the cap layer and reservoirs for geothermal exploration. For a chain microtremor measurement, a two-dimensional (2D) apparent S-wave velocity section can be generated. The apparent S-wave velocity is calculated from the phase velocity using the following empirical method: the 2D apparent S-wave velocity section helps to identify the buried channel for heat flow and track the irregular shapes of the reservoirs or cap layers. It has been verified that the microtremor survey method is reliable and accurate compared with borehole materials. As a newly developed non-invasive geophysical method, it can be widely used in geothermal exploration.

High temperature geothermal systems are widely present along the Himalayan belt in the NW China. Strong manifestations have been observed in the Eastern syntax, where geothermal fluids are alkaline with pH almost higher than 9.0 due to boiling and waters are mainly Cl·HCO3-Na and HCO3-Na types. Large amounts of CO2 from carbonate metamorphism are thought to be one of the reasons of calcite scaling and will be a problem for geothermal energy utilization. However, in the Western syntax, there are no obvious manifestations and geothermal fluid is Cl·SO4-Na type with pH about 7.0. High content of Mg, comparing with that of the Eastern syntax, is assumed to be sourced from dissolution of Mg containing minerals and longer water-rock interactions. Calcite is under-saturated indicating no scaling problem in the utilization. Both of the geothermal fluids are recharged by the local precipitation but with different water vapor sources based on water isotope analysis. Therefore, it’s concluded that geothermal fluids from these two syntaxes have gone through totally different geochemical processes and should be carefully monitored in utilization due to the calcite scaling problem.