Deep Structure of the Central Indian Ocean Inferred from Geophysical Data

摘要

The integrated analysis of data on the heat flow and deep structure of the Earth's crust in the central Indian Ocean reveals additional heat sources (10-20 mW/m~2) beneath zones of tectonic deformations in the Central, Wharton, and Arabian basins that are inconsistent with the geothermal model of lithosphere cooling. These sources may be related to serpentinization of ultramafic rocks. This is confirmed by the seismic Layer 3B with velocities of 7.2-7.6 km/s characteristic of serpentinite is traceable in the lower crust. In contrast to these basins, the heat-flow distribution in the Crozet Basin is consistent with the theoretical geothermal curve. The lack of an additional heat source beneath this basin implies that serpentinites are absent here, as is evident from DSS records (the lack of Layer 3B), and is in agreement with the low seismicity of the basin. Despite the appreciable difference in the geodynamic regime of the respective plates, the spreading rate decreased approximately twofold about 50 Ma ago in the Central and Arabian basins (Indian Plate) and in the Crozet Basin (Antarctic Plate).