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The Greater Xing'an Range (GXAR), situated in the eastern segment of the Central Asian Orogenic Belt, is a prominent orogenic belt that offers an ideal opportunity to explore the dynamic processes underlying lithospheric growth and delamination. A two‐dimensional resistivity model was obtained based on a magnetotelluric survey with 110 stations. The results identified a lateral conductor, associated with the asthenosphere, in the overall high‐resistivity lithosphere of the GXAR. This conductor was recognized as the residual trace of the asthenospheric materials upwelling along the reactivated Xinlin‐Xiguitu suture zone, manifested as the precipitation of metasomes/conductive phases or new lithosphere distributed along channels. The transformation of the GXAR, involving the lithospheric accretion and erosion from the interior, suggests a geodynamic process of thick lithospheric delamination. The erosion of asthenospheric materials from the interior of the lithosphere was deemed as a potential mode of the lithospheric growth and delamination of orogenic belts. The discontinuity of lithospheric thickness, the reactivation of paleo‐sutures, and the tectonic environment leading to mantle convection control the occurrence of this mode. Plain Language Summary: The Greater Xing'an Range (GXAR) is an important and complex orogenic belt in Northeast China. Utilizing the magnetotelluric data, we image a dependable electrical structure to depth of 200 km in the central GXAR, which reveals the laterally residual trace of the asthenospheric materials in the lithosphere. The asthenospheric materials had intruded into the crust‐mantle boundary through the reactivated suture zone, and triggered vertical accretion and lateral erosion of the lithosphere from its interior. It caused the growth and delamination of the GXAR lithosphere. Key Points: The lithosphere of the Greater Xing'an Range features a prominent laterally relatively conductive structureThe asthenospheric materials that intruded along the suture zone transformed the lithosphere of the orogenic beltThe erosion and accretion of asthenospheric materials from the interior of the lithosphere is a potential mode of the lithospheric growth and delamination of orogenic belt [ABSTRACT FROM AUTHOR]

The Huailai area is rich in geothermal resources, but the formation mechanism of its deep heat source is still unclear. In this paper, based on 16 broadband magnetotelluric sounding points, the two-dimensional electrical structure of the crust and mantle in the Huailai area was obtained. Combined with deep seismic reflection and P-wave seismic tomography, the geophysical characteristics of deep heat sources and reservoirs in the Huailai area are described. The Huailai area is characterized by low resistivity and layered reflection above 2 km in depth, which shows the distribution of the Cenozoic sedimentary cover layer. The upper crust is characterized by high resistivity without an obvious reflector, corresponding to the crystalline basement of the basin, whose main lithology is Archean gneiss. There is a highly conductive and bright-spot-reflective structure under the basement, which extends to 100 km, indicating the upwelling of mantle-derived material. Combined with the results of helium isotope tracing, a magma-type geothermal model in the Huailai area is proposed. The upwelling mantle-derived magma material is enriched under the basement to form a heat source. The heat is transferred to the upper crust through heat conduction along the crystalline basement. Then, groundwater circulation brings deep heat to the surface, forming hydrothermal resources.

The cross-gradient joint inversion of gravity and magnetic data is a commonly used way, which requires dividing the subsurface into closely arranged cells with structured or unstructured grids to solve the physical properties of the discrete subsurface. Unstructured grids can more effectively fit undulating terrain and irregular geological bodies than structured grids. However, the existing cross-gradient joint inversion method with structured grids cannot be used to complete the inversion with unstructured grids. We proved that the second-order Taylor formula is more suitable for calculating the cross-gradients of unstructured grids; therefore, we first proposed and implemented the second-order Taylor formula cross-gradient (2-TCG) method for the cross-gradient joint inversion of gravity and magnetic data with unstructured grids, which can calculate the cross-gradient item more easily than other ways because the first few coefficients of Taylor formula are gradient items. The model tests showed that the 2-TCG joint inversion method can accurately achieve the 3-D joint inversion of gravity and magnetic data with unstructured grids, and this method can better describe the detailed information of irregular geological bodies in complex terrain. To explore the minerals and analyze the metallogenic model in the Huanggang–Ganzhuermiao metallogenic belt of the southern Greater Khingan Range, Inner Mongolia, we measured gravity and magnetic data on a scale of 1:10000. We estimated the mineral distributions with 150–280 m depth by 2-TCG joint inversion. We analyzed the relationship between ore bodies and faults, and we established a mixed metallogenic model of the skarns and hydrothermal veins in the survey area. [ABSTRACT FROM AUTHOR]