ГИДРАТАЦИЯ ВЕРХНЕЙ МАНТИИ И ТЕКТОНИКА ОКЕАНИЧЕСКОЙ КОРЫ

Abstract

The joint analysis of the results of geological and geophysical studies of the oceanic lithosphere and modern models of theoretical geodynamics allows us to distinguish three main types of hydration of the upper mantle with ocean water and their subsequent serpentinization. The first type includes frontal hydration, bilateral with respect to the axial zones of the middle ridges on their flanks along the system of microcracks, which leads to the formation of a plastic serpentinite layer with a thickness of about 2 km in the bottoms of the crust. This leads to the formation of cover-thrust structures in the compression zones. The second type is associated with the penetration of ocean water in the zones of stretching along large crust cracks into the upper mantle, where the depth of the Hess isotherm limits serpentinization. In this case, subvertical protrusions and sills are formed in the sides of the faults. The reduced density of serpentinites stimulates a subvertical rise of the overlying blocks of the cortex. The third type is the complex process of the formation of serpentinites in the subduction zones in the moving plate during the hydration with ocean water from above and in the coming plate as a result of dehydration from the bottom. At the same time, the dehydration of the moving ocean plate makes it fragile and can stimulate strong earthquakes. Serpentines formations have a high magnetization and make a significant contribution to the anomalous magnetic field in oceanic areas.