Tuesday, 28 August 2007
2.PS-62
Development of deep extensional basins associated with the sinistral transcurrent fault zone of the Scotia-Antarctic plate boundary
F. Bohoyo1, J. Galindo-Zaldivar2, A. Jabaloy2, Andrés Maldonado3, J. Rodriguez-Fernandez4, A. A. Schreider5, and Emma Suriñach6. (1) Marine Geology, Instituto Geologico y Minero de España, La Calera, 1, Tres Cantos, 28760, Spain, (2) Geodinámica, Universidad de Granada, Facultad de Ciencias, Granada, 18071, Spain, (3) Instituto Andaluz Ciencias de la Tierra, CSIC/Universidad Granada, 18002 GRANADA, Spain, (4) Instituto Andaluz de Ciencias de la Tierra. CSIC-Univ. de Granada, Facultad de Ciencias, Granada, 18071, Spain, (5) P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, 23 Krasikova, Moscow, 117218, Russia, (6) Departament de Geodinàmica i Geofísica, Universitat de Barcelona, 08028 Barcelona, Spain
The Scotia–Antarctic plate boundary is a very complex tectonic zone involving both oceanic and continental elements. The main active structures observed in the area include releasing and restraining bends, with related deep transtensional and probable pull-apart basins. The western sector of the plate boundary crosses fragmented continental crust of the western South Scotia Ridge (SSR), with wide development of pull-apart basins and releasing bends deeper than 5000m. The eastern sector of the SSR is located within the continental Discovery Bank. On its southern border, strike-slip and normal faults produce a 5500 m deep trough that may be interpreted as a pull-apart basin. In both the eastern and western SSR, despite extreme continental crustal thinning, the basins show no development of oceanic crust. This geometry is conditioned by the distinctive rheological behaviour of the involved crusts, with the bulk concentration of deformation occurring within the rheologically weaker continental blocks.