139736eo.pdf (20MB) - Japan Oceanographic Data Center

The latest tectonic generalization is the International Tectonic Map of the World, scale 1:15million, presented at the International Geological Congress in Moscow in 1984. The structure of theocean bottom on most tectonic maps is now interpreted from the stand-point of plate tectonics.FUTURE STUDIESThe detailed research in different regions has revealed the great complexity of bottom structureof the Indian Ocean: for example, great differences in morphology and geophysical character along theocean ridges, the block structure of the so-called aseismic rises, different geological-geophysicalcharacteristics of different blocks, the zones of intraplate deformations, etc. W e believe that these dataindicate the heterogenity of the Ocean bottom and that they cannot be interpreted from the standpoint ofplate tectonics alone. Further research using new techniques, such as multibeam echosounding,submersibles, etc., and accumulation of new data can bring us closer to the solution of many complexproblems for which there are as yet no unambiguous answers.The next stage in the geological study and mapping of the ocean bottom should be carried outon geotraverses, that is, coast-to-coast strips of detailed research crossing different structures.Trans-Atlantic Geotraverses (TAG) in the North Atlantic was the first of such studies (RONA, 1980).At present similar studies are being carried out between Angola and Brasil in the band about 2" wide(from 11" to 13"s). Similar traverses in the Indian Ocean will help to reveal the nature of the transitionand conjugation of different types of structures to allow for construction of three- dimensional modelsof Ocean bottom structure.REFERENCESAGAPOVA, G.V., EFIMOV, V.N., ILLARIONOV, V.K., TURKO, N.N, UDINTSEV, G.B. andZAKHAROV, M.V. (1983). Geomorphology of some aseismic rises of the World Oceanbottom (Geomorfologiya nekotoryh aseismichnyh podnyatiy dna Mirovogo okeana). In:Problemy okeanizatsii Zenli. Izd. Kaliningradskogo Univ., Kaliningrad, 137- 148.ATLAS OF THE WORLD (Atlas Mira) (1959). Moskva, GUGK.BEZROUKOV, P.L. and NEPROCHNOV, YU.P. (eds.) (1983). Eastern part of the Indian ocean:geology and geophysics (Geologiya i geofisika dna vostochnoy chasti Indiyskogo okeana).Moskva, izd. "Nauka", 255 p.BOWIN, C., WARSI, W. and MILLIGAN, J. (1982). Free-air gravity atlas of the world. Geol.Soc. Am. Map and Chart series, N Mc-46.CURRAY, J.R. and MOORE, D.G. (1974). Sedimentary and tectonic processes in the Bengal deepseafun and geosyncline. In: C.A. Burk and C.L. Drake (eds.), The geology of continentalmargins, Springer-Verlag, New York, 617-627.EITTREM, S.L. and EWING, J. (1972). Mid-plate tectonics in the Indian Ocean. J. Geophys. Res.,77, 6413-6421.ENGELIS, T. and RAPP, R. (1984). Global Ocean circulation pattern based on SEASAT altimeterdata and GEML2 field. Mar. Geophys. Res., 7,55-67.FEDOROV, V.V. and DANJLOV, I.V. (1978). Central part of the Mascarene Ridge: bottomtopography studies. (Issledovanie relyefa centralynoy chasti Maskarenskogo khrebta).Geomorfologiya, 4.FISHER, R.L. (1968). Bathymetry of the Indian Ocean, scale 1:2,000,000. Scnpps Inst. Oceanogr.,La Jolla, CA.83