Inversion Of Density Structure For Lunar Crust And Upper Mantle Using Gravity Multi-scale Analysis Technique

The use of an effective method to retrieve the fine three-dimensional lunar crust and mantle structure is of great significance for understanding the formation and evolution of the moon,the morphological structure of Mascon basin,and the future exploitation of new energy sources.The lunar seismic wave method commonly used to retrieve the structure of the lunar crust and mantle is limited by the scarcity of lunar seismic stations,and the spatial resolution of the three-dimensional results is insufficient.With the development of gravity measurement technology,gravity methods are becoming more and more competitive,but there is also the problem of insufficient vertical resolution.Gravity multi-scale analysis technology has been proved to be able to effectively improve this problem and has a wide range of applications in the inversion of the fine structure of the earth's interior.In this thesis,based on the spherical harmonic coefficient of the GRGM1200 A gravity field model of the latest GRAIL satellite,the wavelet multi-scale analysis technique is used to retrieve the fine three-dimensional density structure of the lunar crust and last mantle and the crust-mantle interface depth in the three Mascon regions of the Crisium,Imbrium and Serenitatis,and make a comprehensive analysis and interpretation.The main conclusions and understandings are as follows:(1)the results of stratified density inversion show that in the Crisium basin,there is a high-density body with a small top and a large bottom,with a central position of longitude59 °E and latitude 17 °N,a rough depth range of 32.7 km-64.4 km,and a maximum bottom diameter of 660 km.In the Imbrium basin,there is a high-density body with a small top and a large bottom,similar to a cone,whose central position is about 18 °W longitude and 40 °N latitude,with an approximate depth range of 38.8 km-117.8 km,an ellipsoid at the bottom and a maximum diameter of close to 780 km.There is a high-density material body with small top and large bottom in Serenitatis basin,the top is located on the right side of the basin center,and the bottom is located on the left side of the basin center.Its central position is about 15 °W longitude and 25 °N latitude,the approximate depth range is 41.2 km-69.8km,and the maximum diameter of the bottom is 540 km.(2)the inversion results of crust-mantle interface show that there is obvious uplift at crust-mantle interface in Crisium basin,the uplift within the basin is obviously suppressed,and there is annular anomaly.The lowest depth of crust-mantle interface is 9 km.There is obvious uplift at crust-mantle interface in Imbrium basin,and the uplift trend in the basin is not smooth.There is an obvious uplift at the crust-mantle interface in Serenitatis basin,and the uplift area is more massive and discrete,and the lowest depth of the crust-mantle interface is 6 km.(3)the results of profile density inversion show that there are symmetrically distributed structural faults with a depth of 18 km in the southwest-northeast section of the Crisium basin,12 km in the southwest-northeast section of the Imbrium basin,14 km in the northwest-southeast section,and 28 km in the southwest-northeast section of Serenitatis basin.(4)the internal topography of Crisium,Imbrium and Serenitatis basin is relatively low,but there is no high correlation between this low topography and the characteristics of Mascon,which can rule out the possibility that topographic factors are the main cause of Mascon.Combined with the results of stratified density inversion and the results of crust-mantle interface,it can be inferred that the three regional Mascon basins may be driven by internal high-density materials and crust-mantle uplift,and there are obvious crust-mantle uplift inhibition and tectonic faults in the basin.(5)Gravity multi-scale analysis technology can effectively improve the vertical recognition ability of gravity data,obtain more fine three-dimensional lunar crust and last mantle structure,reveal the internal characteristics of lunar Mascon basin,and restore more real lunar internal structure.