One of the actual problems for oceanic geology is studying origin, composition and structure of the third layer of the oceanic crust (lower third layer of four kilometers in depth, separated from the mantle by Moho boundary, at which an abrupt increase of seismic waves velocity occurs). The subject of my study is plutonic rocks in axial and crestal zones of the Mid-Atlantic Ridge in Central and Equatorial Atlantic. These rocks are bottom areas with different tectonic structure. Based on bathymetric data, I studed composition, structure, and geochemistry of plutonic rocks, as well as the composition of their rock-forming minerals, and analyze the tectonic structures of bottom. In my work, I have allocated 6 tectono-magmatic types among the complexes plutonic rocks: (i) of rift valleys, (ii) zones of non-transform offsets, (iii) zones of transform faults, (iv) smt. Peyve, (v) boreholes of 1275 ODP and (vi) alkaline gabbro. The 7-th type has projected for the central parts of spreading segments. I conclude that peculiarities of the tectonic-magmatic complexes and their rocks depend on the geometry of axial mantle upwelling, transform effect, the tectonic structure of the bottom and the heterogeneity of the upper mantle.

Изучены состав, геохимия, структура и состав пород 3-го слоя океанической коры, отобранных из осевой и гребневой зон Срединно-Атлантического хребта в Приэкваториальной Атлантике. Они объединены в 7 тектоно-магматических типов комплексов плутонических пород, представляющих участки дна с различной тектонической структурой.