Structure and Rheology of Tectonosphere Beneath the Okhotsk-Chukotka Volcanic Belt

Rheological gravity models displaying the deep structure of the crust and upper mantle of the Okhotsk–Chukotka volcanic belt are analyzed and correlated with the composition and age of volcanic events. Volcanic eruptions are established to be spatially connected to areas of minimum density contrast within the astenosphere and/or subcrustal layer. Viscous or partially melted magmas, the source of volcanic eruptions, tend to accumulate in these zones. There are signs of magma rising to the surface due to the movement of rigid slabs in the subduction zone between the Sea of Okhotsk and Pacific plates. The heterogeneity of the structure and composition of the volcanic belt along strike is determined by the structure and composition of the tectonic complexes beneath the belt. On the strength of all the evidence, the Okhotsk–Chukotka volcanic belt is a volcanic rift similar in structure and evolution to the East African Rift.