Moho depth model for the Central Asian Orogenic Belt from satellite gravity gradients. Issue 9 (12th September 2017)

• Record Type: Journal Article
• Authors: Guy, Alexandra; Holzrichter, Nils; Ebbing, Jörg
• Is Part Of: Journal of geophysical research. Volume 122:Issue 9(2017)
• Page Start: 7388
• Page End: 7407
• Publication Date: 2017-09-12
• Subjects: GOCE gravity gradient data -- Moho depth -- inverse gravity modeling -- 3‐D forward gravity modeling -- Central Asian Orogenic Belt; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1002/2017JB014120
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: The main purpose of this study is to construct a new 3‐D model of the Central Asian Orogenic Belt (CAOB) crust, which can be used as a starting point for future lithospheric studies. The CAOB is a Paleozoic accretionary orogen surrounded by the Siberian Craton to the north and the North China and Tarim Cratons to the south. This area is of great interest due to its enigmatic and still not completely understood geodynamic evolution. First, we estimate an initial crustal thickness by inversion of the vertical gravity component of the Gravity Field and Steady‐State Ocean Circulation Explorer (GOCE) and DTU10 models. Second, 3‐D forward modeling of the GOCE gravity gradients is performed, which determines the topography of the Moho, the geometry, and the density distribution of the deeper parts of the CAOB and its surroundings, taking into account the lateral and vertical density variations of the crust. The model is constrained by seismic refraction, reflection, and receiver function studies and geological studies. In addition, we discuss the isostatic implications of the differences between the seismic Moho and the resulting 3‐D gravity Moho, complemented by the analysis of the lithostatic load distribution at the upper mantle level. Finally, the correlation between the contrasting tectonic domains and the thickness of the crust reveals the inheritance of Paleozoic and Mesozoic geodynamics, particularly the magmatic provinces and the orocline which preserve their crustal features. Key Points: The isostatic state of central Asia is undercompensated in its southern area, whereas the northern part is overcompensated The 3‐D forward gravity gradient modeling shows correlations between the contrasting tectonic domains and the crustal thickness of the CAOB The topography of the Moho suggests that the Paleozoic and Mesozoic magmatic provinces and the orocline preserve their crustal features