SATELLITE IMAGES AND TECTONICS OF THE LOW ER 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 dive rsity of the lithologies, the finite strain intensity and the related tectonic transposition allow remote sensing analysis to be used to cha racterize the tectonic pattern. On SPOT images, the structural trends related to radiometric pixel contrasts correspond to the main foliatio n planes measured in the field. The deduced finite strain pattern indi cates that, in this part of the Madagascar Precambrian lower crust, th e deformation is strongly localized within transcurrent shear zones.