The Crust and Upper Mantle in the Zone of Junction between the Central Asian and Pacific Fold Belts

Spatial distributions of the gravity inhomogeneities and their comparative rheological parameters estimated from the density contrast of the crust and upper mantle of northeastern China are analyzed. The features of rheological layering of the tectonosphere and deep spatial relationships between tectonic structures (cratonic blocks, marginal terranes, and sedimentary basins) are revealed. The formal signs of Paleozoic subduction of the North China Craton and Mesozoic subduction of the Pacific plate beneath the Amurian Plate are distinguished in the density contrast distributions. The crustal deformations contrast sharply with the upper mantle deformations, which can be explained by the different directions of tectonic stresses in the Paleozoic and Mesozoic. The indications of upthrusting of the Jiamusi and Khanka continental marginal terranes on the lower lithosphere of the Amurian plate are inferred. The rheology and deep structure of northeastern China have much in common with other regions of the Pacific western margin in Asia and Australia.