Thursday, 30 August 2007 - 4:20 PM
4.P2.B-3
Early opening of Drake Passage: regional seismic stratigraphy and paleoceanographic implications
Andrés Maldonado1, Fernando Bohoyo2, Jesus Galindo-Zaldivar3, F. Javier Hernández-Molina4, Francisco Jose Lobo1, Anatoly A. Shreyder5, and Emma Suriñach6. (1) Instituto Andaluz Ciencias de la Tierra, CSIC/Universidad Granada, 18002 GRANADA, Spain, (2) Instituto Geológico y Minero de España, Rios Rosas 23, Madrid, Spain, (3) Departamento de Geodinámica, Universidad de Granada, 18071 Granada, Spain, (4) Departamento de Geociencias Marinas, Facultad de Ciencias del Mar, 36200 Vigo, Spain, (5) P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia, (6) Departament de Geodinàmica i Geofísica, Universitat de Barcelona, 08028 Barcelona, Spain
The tectonics and distribution of seismic units of the central and southern Scotia Sea are described based on multichannel seismic profiles and magnetic anomalies. Recently acquired profiles suggest that spreading in the Drake Passage was active prior to 30.9 Ma, although the tectonics of the area suggest that rifting of the margins and shallow gateways existed well before that time. After breakup, the Scotia Sea developed from several spreading centers that produced deep ocean basins. Five main seismic units are identified in the Cenozoic sedimentary section. The three youngest units exhibit similar seismic facies and are correlated at regional scale. They contain a variety of contourite drifts resulting from the interplay between the northeastward flow of the Weddell Sea Deep Water, the Antarctic Circumpolar Current and the complex bathymetry. These units were deposited after the Middle Miocene connection between the Scotia Sea and the Weddell Sea was established.