The peculiarities of the crustal structure within the Falkland Basin have been discussed. Maps of the free-air and Bouguer (2.3 g/cm 3 ) gravity anomalies and their transforms have been made. The complex analysis of the anomalous gravity field has allowed us to confirm the continental origin of the crust. The zoning of the crust has been performed. The crust is thinned and is enriched in basic and ultrabasic intrusions. A map demonstrating the distribution of the faults within the studied water area has been made. A conclusion has been reached about the leading role played by tension processes throughout the evolution of the crust within the studied water area.

An electronic databank including the results of seismic investigations and schemes of the sediment thickness’s distribution patterns was built up for two seismostratigraphic complexes in the Falkland Basin. The interface’s border was dated, and the sedimentation rates were estimated for each complex. An integrated map of the cumulative thickness of the deposits and sedimentation rates was developed. The lowest limits of the parameters of the sedimentation process were characterized for the sedimentary layers affected by compaction and erosion.

The seismicity of the northeastern part of the Indian Ocean in connection with the general structural peculiarities of the main tectonic structures of the bottom is presented. The three main ranges of higher seismic activity at the depths of 0–17, 20–27, and 32–35 km divided by aseismic layers are revealed. The seismic activity at depths of more than 35 km is almost not detected both for the ocean and for the Indian peninsula. The nature of the distribution of the seismicity as such in the lithosphere is discussed. Using the results of anomalous au]gravitational field transformations, the prolongation of the East Indian Ridge structure is revealed to 19 degrees north, while the relationship of the Afanasy Nikitin Rise and the 85th Degree Ridge is not reflected at the tranforms. In the Cocos Basin, the mutually perpendicular disturbance zones of northeastern and northwestern strike, as well as the point of their crossing, where the maximal number of earthquake foci are concentrated, are distinguished. A conclusion concerning the substantial disturbance of the strength properties of the lithosphere in this zone as a consequence of the geodynamical processes, which are accompanied by fracture tectonics, is reached.

A digital database on the seismostratigraphy of the oceanic crust of the northeastern part of the Indian Ocean is compiled. In the first layer of the crust, the interval seismic wave velocities are 3.02 ± 0.16 km/s; in the second layer, they equal to 5.31 ± 0.27 km/s; and, in the third layer, the values are 6.46 ± 0.30 km/s. The bottom of the third seismic layer is represented by mantle rocks with an average velocity of 8.10 ± 0.16 km/s. Schemes of the distribution of the thicknesses of the second and third layers of the oceanic crust, of the total thickness of the crust, of the surface of the basement, and of the Mohorovicic discontinuity for the area considered are presented. The schemes compiled allow one to update and complement the ideas about the configuration of the major tectonic structures of the area.

An electronic databank on the seismostratigraphic units based on seismic studies in the northeastern Indian Ocean is created and schematics of the sediment thickness distribution over its area are compiled. For each unit, the interface boundaries are dated, the matter composition is identified, and the sedimentation rates are estimated. An integrated map of the total thickness of the sediments and rates of their sedimentation are constructed. The lower limit of the parameters of the sedimentation process for the sedimentary layers after their compaction caused by the weight of the overlying layers is characterized.

An analysis of the gravity field and geoid heights allowed us to distinguish a third buried basin filled with sediments located in the southwestern part of the sea in the regions adjacent to the Carlsberg Ridge. From the previously known basins, it is separated by saddles. The saddles correspond to a series of faults and are possibly related to the pulse character of the northwestward prograding of the spreading axes of the Carlsberg Ridge. The continental origin of the Laxmi ridge is confirmed. The results of an analysis of the gravity field and its transformants, together with the two- dimensional density modeling, agree with the possibility of the existence of a spreading type of the crust ( I) in the region of the Laxmi Basin. An analysis of the geoid height anomalies allows us to suggest that, with respect to the upper layers of the lithosphere, the Laxmi Ridge is not connected with the Chagos - Laccadive Ridge.

Based on seismic data, the first schematics of the thicknesses of the second and third seismic layers were compiled to-ether with schematics the thicknesses of the consolidated and overall (including the sediments) earth's crust in the northern Arabian Sea. The latter varies from 6 kin in the Arabian Basin up to 18 km on the eastern slope of the Laxmi Ridge. Also compiled were schematics of the topography of the bottoms of the first, second, and third seismic layers in the northern Arabian Sea. For the first time, in the basin of the Arabian Sea, two depressions filled with sediments were recognized: the northern (with the depth of the basement up to 8 km) and the southern (with the bottom lying at a depth of about 6 km). North of the Laxmi Ridge, for the first time, a rise "J," whose origin is presumably similar to that of the Laxmi Ridge, and a curved depression "Sh" about 200 kin long and 100 km wide were discovered. A depression in the Mohorovicic discontinuity up to 22 kin deep is confined to the foot of the eastern slope of the Laxmi Ridge.

Maps of the distribution of the thicknesses of principal seismostratigraphic sediment complexes in the northern part of the Arabian Sea are compiled from the seismic data. The overall thickness of the sediments is about 4-8 km, except for the Laxmi ridge crest area, where it does not exceed a few hundred meters. The sedimentation rates reached 9-10 cm/ky and greater. The maximum sedimentation rates (no less than 18-20 cm/ky) are confined to the interval older than 50 Ma.

New gravimetric charts of the Southern Pacific ocean (taking into account the altimetry data) and charts of chrons are presented. The relation between the ages was the foundation for the construction of the present day version of the sea floor age chart based on the gravity and magnetic anomalies. The relation between the age and thickness of the lithosphere obtained as a result of gravity modelling of the Earth was the basis for the chart of lithosphere thickness and computation of the density crossections for the lithosphere, astenosphere, along the profiles crossing the main morphostructures of the Southern Pacific. The updated charts allow us to make a correction of the tectonics and paleogeodynamics of the South Pacific.

The charts of gravity anomalies in several reductions were constructed based on the ship and altimeter gravity data (averaged over one degree trapezes) in the southern part of the Indian ocean. These charts are the most complete for this region. The chart of paleomagnetic axes was also constructed. The geodynamic history of the region was analyzed on the basis of this chart. Using the gravity and magnetic charts the scheme of the lithosphere thickness was created. This scheme is based on the correlation between age-thickness, Glenny anomaly-agethiskness. Two-dimensional density modeling was performed for several profiles. The reliability of the scheme of the lithosphere structure was shown.

New gravimetric charts of the South Atlantic (taking into account the altimetry data) and charts of chrons are presented. The relation between the ages was the foundation for the construction of the present day version of the sea floor age chart based on the gravity and magnetic anomalies. The relation between the age and thickens of the lithosphere obtained as a result of gravity modeling of the Earth was the basis for the chart of lithosphere thickness and computation of the density crossections for the lithosphere, astenosphere, along profiles crossing the main morphostructures of the Southern Atlantic. The updated charts allow us to make a correction of the tectonics and paleogeodynamics of the South Atlantic.