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Moho; north-eastern Eurasia; gravity field; gravity gradients; residual topography
Abstract:
We present a new Moho map for the north-eastern part of Eurasia, which remains almost non-studied by seismic methods. The new map is based on the analysis of various data sets. The key fields are the residual gravity, topography and vertical gravity gradients of GOCE (Gravity field and steady-state Ocean Circulation Explorer). Using three fields enables improvement of the final results and better separation of the Moho effect. In the first step, the effects of sediments, crystalline crust and upper mantle were removed from the observed fields based on existing crustal and tomography models. The residual fields are then inverted in the next step to find perturbations in the initial Moho map. In the inversion, it is assumed that some density anomalies are still located in the crust and upper mantle. The new Moho map demonstrates several principal features, which were not resolved before. They well correspond to tectonic fragmentation of the study area. In particularly, the crustal root is now located under the Verkhoyansk Range and extends to the depth of 47 km, also the new model demonstrates the Moho deepening in the continental part of the Laptev rift system. Next, the zone of shallow Moho in the East Siberian Sea shore is now clearly traced and has a more isometric shape compared to the initial model. New patterns have been also found in the offshore part of the Chukotka microcontinent and for the Anadyr-Koryak folded system. The new Moho map is a significant improvement of the previous maps showing crustal thickness in north-eastern Eurasia.
