SATELLITE IMAGES AND TECTONICS OF THE LOWER CONTINENTAL-CRUST - THE EXAMPLE OF SOUTH-WESTERN MADAGASCAR

In the South-Western part of Madagascar, a piece of Precambrian lower continental crust outcrops. In this area, the lack of relief, the diversity of the lithologies, the finite strain intensity and the related tectonic transposition allow remote sensing analysis to be used to characterize the tectonic pattern. On SPOT images, the structural trends related to radiometric pixel contrasts correspond to the main foliation planes measured in the field. The deduced finite strain pattern indicates that, in this part of the Madagascar Precambrian lower crust, the deformation is strongly localized within transcurrent shear zones.