Deep processes, velocity, heat and density models of the East Kamchatka upper mantle

Abstract

For the velocity structure of the lithosphere of East Kamchatka, a tomographic model of high spatial resolution was constructed. Model demonstrates clear relation of velocity values in mantle with subsurface structure. The change in velocity of P -waves relative to the average 1D model reaches ±0.6 km/s. Asthenosphere, in other words the interval where velocities are lower than in solidus point, can be seen as well. Seismological model may be used to control model of deep processes in the given region. The circuit of the Alpine and recent deep processes in the crust and the upper mantle of the East Kamchatka and Cronotsky gulf is considered with use of ideas of a advection-polymorphic hypothesis. Consequences of the processes are coordinated with velocity model of the mantle and composition of magmatic rocks. The data on crustal xenoliths and the composition of igneous rocks of different ages and with different depths of centers of partial melting of mantle rocks were used. The depths of the conductors in the upper mantle are consistent with the deep asthenosphere. But the S values for 1D and 2D models are too large. When using a three-dimensional model in the southern part of Kamchatka, the S value of the electrical conductivity objects in the mantle is reduced. Thus, coordination with the thermal model seems possible. The results of construction of density models of tectonosphere along three cross-sections on the East Kamchatka and adjacent aquatorium are considered. For the model of the upper mantle a thermal model corresponding to the structure of a deep process according to the advection-polymorphous hypothesis is used. The mantle gravitational anomaly reaches a large value — more than 200 mGal. Possibility of explanation of the observed gravitational field without the selection of model parameters is shown.