Petrological–Thermomechanical Modeling of the Northern Segment of the Kamchatka Subduction Zone: Thermal Structure, Dehydration, and Magmatism

Two series of numerical experiments are conducted to simulate the initiation and evolution of subduction of the Pacific Plate beneath the northern segment of the Kamchatka subduction zone. The first series modeled the self-evolving submergence at initial kinematic and physical parameters of the subduction zone. The second series additionally tested a new element of the regional subduction model: a zone of kinematic stabilization in the asthenospheric mantle to allow a shallower trajectory of slab submergence. In the first series of numerical experiments (without the stabilization zone) we studied steeply dipping subduction, which is inconsistent with the slab configuration according to available geophysical data, with the full absence of magmatism during the first 14 million years of the model time. In the second series (with the stabilization zone), we simulated the slab configuration from seismotomographic data and plotted the P–T trends (geotherms) for the slab surface and the base of the oceanic crust (Moho boundary). Volcanism was observed in the second series starting after 9 million years of the modeling time. The volcanism is mostly felsic and volcanic structures that are located at a distance of 200 km from the trench; the latter generally corresponds to the spatial arrangement of the Eastern volcanic belt relative to the trench.