Gravity and GPS hybrid measurements were conducted at 385 stations throughout the Qinling Orogen, China, to update Bouguer gravity anomalies and free‐air gravity anomalies of the area. The crustal density structure, lithosphere flexure mechanism, and isostatic state of the Qinglin Orogen were studied in detail via these in situ observations. Bouguer gravity anomalies in the study area are mainly negative, ranging from −410 mGal in the Tibetan Plateau to −100 mGal in the eastern Qinglin Orogen. The estimated crustal thickness ranges from 56 to 35 km and thins eastward along the Qinling Orogen. The optimal effective elastic thickness (Te) of the study area is 14 km, and the loading comes from the Earth's surface, the interface between the upper and lower crust, and the Moho. Vertical tectonic stress borne by the lithosphere varies observably in the study area. Downward stress reaches a peak of −14 MPa in the Liupanshan Mountains, whereas the highest value of upward stress (8 MPa) is attained in the middle Qinling Orogen. Considering distributions of crustal density structures and vertical tectonic stress of the lithosphere, in addition to the distinct loading ratios of the eastern and western Qinling Orogen, a piecewise combination model was developed to interpret the uplift of the Qinling Orogen. This model shows that the eastern part of the Orogen is thickened by the upward migration of mantle materials under the thrusting of the South and North China Blocks, whereas uplift of the western part results from lower crustal flow derived from the Tibetan Plateau.

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The collision of the Eurasian plate by the Indian plate caused extensive deformation in the Asian interior (Molnar & Tapponnier, 1975), resulting in the uplift and outward extrusion of the Tibetan Plateau and the reactivation of the ancient orogenic belts, such as the South Tian Shan and the West Kunlun (Avouac et al., 1993;Yin & Harrison, 2000). The Tarim Basin lies between the above orogens (Figure 1). Numerous deep and large fault zones are distributed in this basin (Lyu et al., 2019), indicating that the region has undergone a complex and long-term tectonic evolution process. It is thus an ideal area for studying the formation of piedmont basin and the geodynamics of the plate convergence.At present, the composition of deep bedrock materials in the Tarim Basin remains uncertain. Some scholars believe that the material of the deep structure of the entire basin may be uniform (Li et al., 2020;Zhang et al., 2013). Others argue that the basin may be split by south and north blocks, because of the abruptly high thermal and magnetotelluric anomalies in the middle-south area (Gao et al., 2013;Qiu et al., 2022;Zhang et al., 2020). The crustal density structure can be inverted from the gravity anomaly to explore the deep material composition. Furthermore, the tectonic evolution

Abstract. Lateral inhomogeneity in Earth’s mantle affects the tidal response. In this study, the analytical method for determining the effect of lateral inhomogeneity on tidal gravity, presented by Molodenskiy (1980), is introduced. Moreover, the current study reformulates the expressions for estimating the lateral inhomogeneity effects with respect to the unperturbed Earth and supplements some critical derivation process to enhance the method. The effects of lateral inhomogeneity are calculated using several real Earth models. By considering the collective contributions of seismic wave velocity disturbance and density disturbance, the global theoretical changes of semidiurnal gravimetric factor are obtained, which vary from −0.22 % to 0.17 % compared with those in a layered Earth model, no more than 1/3 of the ellipticity’s effect. The gravity changes caused by laterally-inhomogeneous disturbance are also computed, and turn out to be up to 0.16 % compared with the changes caused by tide-generating potential. The current study tests the importance of lateral inhomogeneity and other factors. The results indicate that the rotation, ellipticity, and inelasticity on tidal gravity are the most dominant factors, the ocean tide loading is the moderate one, and the lateral inhomogeneity is the least but not negligible factor, because the three-dimensional effect is comparable with ocean tide loading at some locations. Moreover, the amplitude of tidal gravity caused by lateral inhomogeneity is noticeable larger than the precision of superconducting gravimeters.