Ocean Bottom Structure in the Junction Area of the King's Trough and the Gnitsevich Plateau (North Atlantic)

The paper, based on the data obtained during 57-th expedition of the R/V "Akademik Nikolaj Strakhov", examines the structure of the north-western part King's Trough and the Gnitsevich Plateau, forming a mesostructural cluster located on the eastern flank of the Mid-Atlantic Ridge in the North Atlantic. Bathymetric and hydromagnetic surveys, seismoacoustic profiling and bottom sampling by dredging were carried out. It has been shown that this part of the trough consists of 6 basins of different depths, subparallel and continuing each other along the strike, separated by median ridges and ledges. The flanks of the trough are formed by volcanic plateaus, which are built up by multi-dimensional cone-shaped volcanic structures. At the same time, the southern and northern flanks are complementary to each other both in depth and morphology, and merge into a single plateau in the area of the northwestern closure of the trough. An area of volcanic structures of various sizes and morphology was formed around the King's Trough: cone-shaped structures, calderas, the Gnitsevich Plateau of several mountains on a common base. It is shown that the anomalous magnetic field of the study area is a superposition of linear and isometric anomalies, the latter associated with large volcanic mountains. Linear anomalies C6n and younger are located northwest of the King's Trough and are not interrupted, and linear anomalies between C6n and C13n chrones are found only on the flanks of the trough, whereas they are absent in the area of basins. The recovered rock material can be divided into two main associations: spreading (nonporous basalts, dolerites, gabbros, mylonites) and volcanic (porous volcanics close to basalts). The rocks of the first of them form the sides of basins and median ridges, the second - plateaus and volcanic constructions. Limestones, breccias and Fe-Mn crusts are found in both associations. According to seismoacoustic profiling, the sedimentary cover of the study area was formed on oceanic basement that went through neotectonic deformations, with background pelagic sedimentation, landslides, debris flows and material transported by subbottom currents. Preliminary assumptions were made about the origin of the mesostructural cluster: King's Trough - the Gnitsevich Plateau.