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• Obtain 3-D resistivity structure of the Gudui geothermal field by audio magnetotelluric inversion. • Analyze the depth of heat source of the Gudui geothermal field by magnetotelluric inversion. • Establish the geothermal model and study genesis mechanism of the Gudui geothermal field. The Gudui geothermal field, situated in the Shannan region of Tibet, is classified as a shallow high-temperature hydrothermal field controlled by faults. Geothermal wells in this field can reach temperatures of up to 205 °C at a depth of 230 m, making it the highest recorded temperature for geothermal fields in China at that depth. However, the precise nature of the faults and subsurface structures within the Gudui geothermal field remains poorly understood. Therefore, to gain a deeper understanding of the structure and geothermal genesis mechanism of this field, a total of 361 audio magnetotelluric (AMT) stations were deployed, and the observed data was inverted to establish a large-scale three-dimensional resistivity structure of the study region. The obtained resistivity structure revealed multiple geothermal reservoirs underlying the Gudui geothermal field. Additionally, this structure also provided insights into the dip direction of faults, which serve as channels for water and heat flow. Furthermore, through the analysis of other existing magnetotelluric (MT) data and earthquake distribution, we were able to infer that the deep heat source of the Gudui geothermal field is a high-temperature partial melting body located approximately 5 km below the surface. The high-temperature partial melting body may originate from deep crustal heat flow. Finally, we conducted a brief discussion on the potential existence of other geothermal types in the Gudui region. [ABSTRACT FROM AUTHOR]

The Luobusa chromite mine in Tibet, the largest chromite deposit discovered in China to date, is hosted in the Luobusa ophiolite in the eastern section of the Yarlung Zangbo suture zone. A combined seismic reflection and magnetotelluric survey was carried out on the mantle peridotites in which the chromitite deposits occur in order to investigate their origin and to prospect for other deposits in the area. The survey indicates that the Luobusa chromitite-bearing ultramafic block is a tectonic slice thrust onto the southern margin of the Gangdese batholith by multiple south-dipping faults. The maximum thickness of the ultramafic rock mass is 4 km, and it is underlain by the upper crust of the Indian Plate. Low-resistivity bodies in the upper crust of the Luobusa area lie at a depth of up to 5 km, and strata at a depth of 7 km cross the Yarlung Zangbo suture zone at a relatively small angle. Between depths of 20–50 km, there are a number of oval low-resistivity bodies, the lower parts of which might have been close to the Moho at a depth of approximately 65 km near the Yarlung Zangbo River. It is inferred that such low-resistivity bodies arise from partially molten bodies in the middle and lower crust and are related to deep tectonic activity and mantle material upwelling in the Yarlung Zangbo suture zone. [ABSTRACT FROM AUTHOR]

Analyzes magnetotelluric (MT) data from the Tibetan crust in China. Range of integrated conductivity; Indicators of presence of partial melt at shallow depths in the Tibetan crust; High conductivity layer that represents partial melt in the crust; Observations suggesting presence of aqueous fluids in the crust.