Tectonics and Geomorphology of Elephant Island, South Shetland Islands

Abstract

New tectonic and geomorphological data from Elephant Island have been obtained during a cooperative fieldwork campaign carried out in the 2002–2003 season by Brazilian and Spanish groups. The main phases of ductile deformation affecting the high-pressure metamorphic rocks of Elephant Island, D1, D2 and D3, were studied in more detail along a N-S profile in the western sector of the island. D2 was subdivided in two subphases, D2a and D2b. The brittle and brittle-ductile deformation postdating the three main phases was studied systematically for the first time in the island. The measurement of the orientation of more than 200 faults with their kinematics pointed out that normal faults indicating an extensional setting predominate in the southern sector of the island. By contrast, in the northern part of the studied profile, major faults are predominantly reverse, although normal faults are also present, indicating the overprinting of at least two deformation stages. A new 1:50000 topographic map of the island, with 20 m contour interval, was prepared being included in this paper a shadow map from a 3D digital model based on it. Geomorphological features of marine and glacial origin were identified and mapped. The most significant of these are the raised marine platforms up to 150 m a.s.l. at Cape Lindsey area and lower platforms, Holocene raised beaches and moraines at Stinker Point area.