| Due to the collision and compression of the Indian and Eurasian plates,the Qinghai-Tibet Plateau continues to uplift,and its uplift has important implications for regional and even global climate change,but the small coverage of traditional observations of the surface in this region and the difficulty of obtaining them have led to a lack of understanding of the distribution of vertical deformation rates in the crust of the Qinghai-Tibet Plateau.The GRACE provides highly accurate and large coverage data for studying the vertical crustal deformation velocity distribution on the Qinghai-Tibet Plateau.This paper uses GRACE data from 2003-2020 to calculate the time-varying gravity field of the Qinghai-Tibet Plateau.Gravity fields from hydrological changes are calculated using glacier,lake,soil moisture,denudation,permafrost and snow water equivalent data,and finally the gravity signal of the vertical crustal movement are obtained.The vertical crustal deformation velocity distribution on the Qinghai-Tibet Plateau was inferred based on the upright rectangular model,and the effects of hydrology,crustal thickness and topography on its inversion results were discussed.The main research results are as follows:(1)Under the assumption that the signal from GRACE observations is mainly composed of hydrological factors and vertical crustal movement,the GRACE data is used to obtain the gravity change rate distribution by combining P4M6 and Gaussian filtering,deducting GIA effects,and signal recovery.The gravity effects of glacier,lake,soil moisture,denudation,permafrost and snow water equivalent are deducted to obtain the spatial distribution of gravity change relating to vertical crustal movement.The results show that the northern part of the Qinghai-Tibet Plateau,the Sichuan Basin and the vicinity of the Tianshan region exhibit positive gravity variations with values ranging from～0.00 to 0.15 μGal/a;in the southern part of the Qinghai-Tibet Plateau,the Tarim Basin and the North China Plate,they exhibit negative gravity variations with values ranging from～-0.40 to 0.90 μGal/a;in other regions,the gravity variations are relatively small,with values of～-0.20 to 0.00 μGal/a.(2)Under the assumption that the vertical deformation of the crust includes surface uplift(subsidence)and Moho surface uplift(subsidence),we construct a model for the change of gravitational field caused by the vertical motion of the crust.The Qinghai-Tibet Plateau region(65°E-110°E,20°N-45°N)was first divided into 744 upright cuboids at a spatial resolution of 1°×1°,and the vertical crustal deformation velocity distribution was inferred by taking into account the crustal thickness and topography.The results show that the Qinghai-Tibet Plateau as a whole is spatially unevenly distributed,with positive vertical deformation in almost the entire region except for the Sichuan Basin,the northern part of the Qinghai-Tibet Plateau and the western part of the Tarim Basin.The positive vertical deformation is most pronounced in the southern part of the Qinghai-Tibet Plateau,with a rate of～1.0 mm/a;in the eastern part of the Tibetan Plateau,the rate of vertical deformation is～0.4 mm/a;in the northern part of the Tarim Basin and the North China Plate,the rate of vertical deformation is～0.5 mm/a;in the regions with negative vertical deformation,the Sichuan Basin is the most pronounced,with a rate of～-0.4 mm/a,and in the northern part of the Qinghai-Tibet Plateau,the rate of vertical deformation is～-0.1 mm/a.The rate of vertical deformation in the area between the Qilian Haiyuan Fault and the Kunlun Fault is small,at～0.0mm/a.In addition,we find that the results of this paper are consistent with the distribution of crustal deformation,thrust earthquakes/faults and regional lithospheric activity.(3)The influence of hydrology,crustal thickness and topography on the inversion of the vertical deformation rate field of the Tibetan plateau is analyzed.Hydrology,crustal thickness and topographic factors do not change the overall distribution of the vertical deformation rate of the Qinghai-Tibet Plateau,but there are only numerical differences.The numerical differences of hydrology factors are the most significant,with the maximum difference of-0.4mm/a in the northwest and～1.0mm/a in the middle.Among the hydrology,crustal thickness and topographic factors that affect the vertical crustal movement rate,hydrology is the most obvious,crustal thickness is the second,and topographic is the least.The main factors influencing gravity changes in hydrology are glaciers,lakes and soil moisture,which together account for～79%of the total hydrology. |
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