The Intraplate Volcano-Tectonic Activity in North-Eastern and South Sectors of the Pacific Lithospheric Plates With the Connection of the Change of Its Relative Motion

Abstract

The analysis of altimetric data in combination with bathymetry and gravimetry materials in the north-eastern and southern sectors of the Pacific Ocean, as well as detailed data on the underwater relief, the structure of the sedimentary cover, the composition and absolute age of basalts obtained within the area of domestic geological exploration for ferromanganese nodules (the Clarion-Clipperton zone) is carried out. Structural trends formed by local cone-shaped local structures of presumably volcanic nature, grouped along transform faults belonging to various stages of the kinematics of the Pacific Plate, have been traced in the structure of the oceanic lithosphere at various scale levels. The first trend corresponds to the extension of the fault system corresponding to the spreading system on the crest of the East Pacific rise before the restructuring of its planned geometry in the Paleocene-Eocene, the second coincides with their extension after the change in the relative movement of the Pacific Plate. The trends are characterized by planned disagreement, and an increase in the number of seamounts is observed in the areas of their intersection. Within the area of detailed studies, obvious signs of volcanic-tectonic activity were revealed: high dissection of the underwater relief, hills of different heights with steep slopes, whose volcanic nature is confirmed by differentiated basalts raised from their slopes, the absolute age of which indicates the multistage outpourings that occurred in an intraplate environment. The angular velocity of rotation of the spreading axis and the linear velocity of its advance with changes in the kinematics of the Pacific plate are estimated and possible reasons for changes in its relative motion are considered. An improved scheme of adaptation of the spreading zone to a change in the direction of relative plate movement is proposed, acc0ording to which an essential factor of intraplate volcanic-tectonic activity is the relaxation of stresses in the plate caused by external influence on it.