A seismo-stratigraphic analysis of glaciomarine deposits in the eastern Riiser-Larsen Sea (Antarctica)
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ORIGINAL PAPER
A seismo-stratigraphic analysis of glaciomarine deposits in the eastern Riiser-Larsen Sea (Antarctica) K. Solli Æ B. Kuvaas Æ Y. Kristoffersen Æ G. Leitchenkov Æ J. Guseva Æ V. Gandjukhin
Received: 5 July 2006 / Accepted: 19 January 2007 / Published online: 14 February 2007 Ó Springer Science+Business Media B.V. 2007
Abstract Multichannel seismic data from the eastern parts of the Riiser-Larsen Sea have been analyzed with a sequence stratigraphic approach. The data set covers a wide bathymetric range from the lower continental slope to the abyssal plain. Four different sequences (termed RLS-A to RLS-D, from deepest to shallowest) are recognized within the sedimentary section. The RLS-A sequence encompasses the inferred pre-glacial part of the deposits. Initial phases of ice sheet arrival at the eastern Riiser-Larsen Sea margin resulted in the deposition of multiple debris flow units and/or slumps on the upper part of the continental rise (RLS-B). The nature and distribution of these deposits indicate sediment supply from a line or a multi-point source. The subsequent stage of downslope sediment transport activity was dominated by turbidity currents, depositing mainly as distal turbidite sheets on the lower rise/abyssal plain (RLS-C). We attribute this to margin progradation and/or a more focussed sediment delivery to the continental shelf edge. As the accommodation space on the lower rise/abyssal plain declined and the base level was raised, the turbidite channels started to backstep and develop large channel–levee complexes on the upper parts of the continental rise (RLS-D). The deposition of
K. Solli (&) B. Kuvaas Y. Kristoffersen Department of Earth Science, University of Bergen, 5007 Bergen, Norway e-mail: [email protected] G. Leitchenkov VNIIOkeangeologia, 1, Angliysky Ave., 190 121 St. Petersburg, Russia J. Guseva V. Gandjukhin PMGRE, 24, Pobedy Street, 189510 Lomonosov, Russia
various drift deposits on the lower rise/abyssal plain and along the western margin of the Gunnerus Ridge indicates that the RLS-D sequence is also associated with increased activity of contour currents. The drift deposits overlie a distinct regional unconformity which is considered to reflect a major paleoceanographic event, probably related to a Middle Miocene intensification of the Antarctic Circumpolar Current. Keywords Antarctica Debris flows Deep-sea deposits Riiser-Larsen Sea Seismics Turbidites
Introduction The eastern Riiser-Larsen Sea constitutes a relatively ‘‘new’’ region of the circum-Antarctic margin in terms of seismic data availability. Recent efforts in the area (Kuvaas et al. 2004a, b) have mainly focussed on the description of main morphological elements and the interpretation of prominent seismic facies in terms of processes. These initial studies emphasized a need for further seismic investigations in order to improve the spatial stratigraphic resolution of the sedimentary record and to increase our understanding of the dynamics of deep-marine sedimentation in the region. I
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