Recent progress in magnetic anomaly mapping over Victoria Land (Antarctica) and the GITARA 5 survey

Magnetic anomaly mapping is used to interpret crustal structure and tectonic evolution of Victoria Land and of the adjacent Ross Sea. Previous interpretation of magnetic anomalies verified seismic and gravimetric findings in the Ross Sea by placing additional constraints both on crustal structure and magmatism of the West Antarctic rift system. An aeromagnetic map of the central-southern part of Victoria Land produced in the framework of the GITARA project, provides new crustal images of part of the Trans antarctic Mountains rift shoulder. The map was interpreted to study the transition between the Wilson Terrane and the Precambrian East Antarctic Craton, the extent and distribution of Jurassic tholeiitic magmatism, and the occurrence of post-Jurassic faulting oblique to the rift basins. A compilation with adjacent aeromagnetic data was recently used to study the structures inherited from the Palaeozoic terranes and their reactivation as major fault zones separating different crustal blocks along the TAM rift shoulder. Additional aeromagnetic coverage over a 35 500 km(2) sector of northern Victoria Land was acquired during the GITARA 5 (1996/97) survey. The flight altitude was 9000 ft and profile line spacing was 4.4 km for the regional grid and 2.2 km for the detailed one, with a tie line interval of 22 km. Standard processing techniques, optimized with microlevelling procedures were applied to the data to produce a 1:250 000 magnetic anomaly map. The processed GITARA 5 magnetic dataset is a new tool to study the structure of the Rennick Graben, and its relationship to the Palaeozoic Wilson Terrane-Bowers Terrane and Robertson Bay Terrane suture zone. The new map also represents important progress towards a magnetic anomaly compilation over the whole of VictoriaLand, since it links previous efforts near the Pacific Coast with those near the Ross Sea.