Left- and right-looking RADARSAT-2 data for mosaics of ancient supercontinents

The Pangaea supercontinent began its break-up some 200 Ma ago, during which time the ancient cratons of West Africa and San Francisco-Congo of Gondwana were rifted apart. These older parts of the continental crust now reside in the African and South American shields, but share a common geological past. Geological maps of reconstructed Pangaea aid geologists to understand the tectonic history of the evolving Earth, the global distribution of rock units and ore deposits. It follows that radar and other remotely sensed images of Earth can be mosaicked in the same fashion to provide supplementary information in support of such investigation. In our radar mosaic for part of Gondwana, left-looking RADARSAT-1 data of west Africa acquired on ascending passes during the Antarctic Mapping Mission and normal mode (right-looking) data of South America from descending passes were first seamed together separately. The two continental image maps were then rotated into their pre-breakup configuration to create a radar mosaic with a relatively consistent westward radar look. This critical aspect of the mosaic would not be possible from a SAR system without left- and right-looking capability. A consistent look direction is of great importance when landform interpretations are made. The left and right pointing of the RADARSAT-2 antenna will enable routine data collection of this kind for similar studies.