Earth’s crust and physical fields of the oceans

Abstract

Some problems of the formation and development of oceanic regions with various variants of endogenic regimes (with the exception of island arcs, which, in the author’s opinion, belong to late Alpine geosynclines) are considered. Calculated geological events and anomalies of physical fields within them are determined by heat-mass-transfer schemes in the tectonosphere. The reliability and accuracy of the latter is related to the quantity and quality of information about the content of the regimes. In the oceans, such data is scarce. The article attempts to attract additional information about the formation of the Earth’s crust of a typical oceanic basin. It was presented in the form of oceanization (destruction and basification) of the continental crust with a slightly increased basicity. The process included the uplift and denudation of the upper block up to 10 km thick, the intrusion of mafic and ultrabasic rocks from the mantle in a concentration increasing with depth into the lower approximately 20—30 km of the crust. Seismic wave velocity and density in the crustal basement were almost equal to the properties of the warmed mantle rocks. The final stage of magmatism was presented in a large part of the region during the period of recent activation by the removal of partially molten matter from the shallow asthenosphere up to the surface. Similar models have also been constructed for other endogenous regimes. In all cases, significant scatter in the ages of the process stages and the order of formation of asthenolite sources rising from different depths of the upper mantle were unavoidable. The resulting thermal models were averaged effects for the considered variants of heat and mass transfer. The control of the reality of these constructions was carried out according to the correspondence of known events of geological history, allowing a quantitative description, and anomalies of physical fields. In this work, the second part is considered. The calculated velocity sections of the upper mantle regions, the heat flow distribution, and the values of mantle gravity anomalies were compared with the experimental data. In all cases, the agreement reached is satisfactory. The discrepancies can be explained by errors in observations and calculations