Chemial and isotope compositions of rocks from the West Antarctic

The paper is devoted to a marine geophysical-geological research in the West Antarctic. This researche contributed to establishing the base geodesic network of the West Antarctic and supplemented geokinematic monitoring based on this network with geophysical and geologic information on structure and features of geomorphological and tectonic development of the South Ocean floor. Collected materials allow to conclude about the inhomogeneity of the Scotia Sea floor and about combination of fragments of a continental massif with young rift structures in conditions of the upwelling mantle. The ancient continental bridge, faunal connections between the South America and the West Antarctic has been destroyed by processes of destruction, taphrogeny and sea floor spreading. Structures of the Scotia and Caribbean Seas, North Fiji and Arctic Basins are similar

Chemical composition of rocks and minerals from the Weddell Sea

Studied samples represent bedrock occurrences rather than products of transportation by floating ice. Two regions were distinguished: the East Antarctic margin (submarine Maud Ridge) characterized by intensive destruction and oceanization of the continental crust, and the northwestern part of the Weddell Sea (Powell Basin), where spreading processes are superimposed on the weakly destructed continental crust. Volcanic rocks of the Maud Ridge derive from an enriched mantle source. The following geologic section was observed: young fresh porous basaltic porphyrites underlain by older massive basaltic porphyrites metamorphosed under greenschist-facies conditions. Presence of granulite-facies rocks suggests continental origin for these rocks. Mineralogical and geochemical features of magmatic rocks collected from various areas of the Weddell Sea floor may indicate contribution of deep fluids. We believe that the magmatic replacement of the Precambrian granite-metamorphic complex of the continental basement by basic-ultrabasic mantle material played the main role in transformation of the continental crust into the secondary oceanic crust. This process occurred under significant contribution of fluid flows and uneven activity of geologic processes, in contrast to formation of the primary oceanic crust because of seafloor spreading. Our results suggest that the basement of the Weddell Sea is of continental origin and has experienced extensive destruction