Geophysical processes and biosphere: article

Аnnotation: The morphostructural characteristics of southern sector of the Indian Ocean, its main taxa - the Del Cano-Crozet plateau, Conrad and Kerguelen are given based on structural-tectonic analysis. The authors for the first time built a depth map of the acoustic basement of the eastern part of the Afro-Antarctic megadepression using the digitized NGDS database on the thickness of the sedimentary cover of the Indian Ocean, which is freely available on the Internet. A critical analysis of deep seismic sounding data acquired on the Kerguelen plateau is carried out. A geochemical analysis of more than 100 samples of basalts, rocks and rocks of sedimentary origin, collected on the islands of the archipelago and raised by dredging and deep-sea drilling from the Kerguelen and plateaus, has been carried out. As a result of the research, it was found that the indicated plateaus in terms of morphostructural features and a number of other features resemble the Madagascar ridge. It is concluded that these flat horst massifs, no later than the Paleogene, were part of the «structural bridge» that connected Madagascar and the eastern part of mainland Antarctica. An alternative version of the geological interpretation of the deep seismic data is proposed, from which it follows that the plateau has a relatively homogeneous structure, sustained along the strike, with a thick, at least 15 km, layer of continental crust. Analysis of the depth map of the acoustic basement made it possible to identify depot centers, relatively isolated basins: Enderby, Shackleton and Labuan, framing the Kerguelen plateau on the southern side. The peculiarities of the paragenetic connections of the Kerguelen plateau with the basins indicate that the isolation of the Kerguelen plateau from East Antarctica and the formation of the modern structural plan of the region began in the Late Cretaceous and ended with the last phase of tectonic activation in the Late Miocene-Pliocene. The results of geochemical analysis show that the geochemical and petrological anomalies of the plateau and islands are associated with the crust, and not with the mantle, as well as with the continental nature of the Kerguelen plateau.