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Late Pleistocene Sediment Dynamics in the Southern Galician Margin Gully System

Petrovic, Alexander; Hanebuth, Till J.J.; Lantzsch, Hendrik; Bender, Vera B.

Gullies at continental slopes are ubiquitous erosional elements and served as common conduits for sediments migrating from shallow waters into the deep ocean. However, the particular role of these gully systems in focusing material transport as well as the external parameters determining loci and timing of activity are surprisingly little understood.

The NW Iberian continental slope is known as a highly dynamic sediment system since the Late Pleistocene, dominated by canyons and channels. However, the export processes and sediment pathways from are yet sparsely known. New bathymetry data are presenting a margin of numerous morphological pathways. Especially the southern Galician margin is characterized by a complex gully system. To figure out the importance of the gully system for the down-slope sediment export over the past 60 ka, hydroacoustic data and nine sediment cores were collected and analyzed.

The results are presenting a diversified export system. Before 30 ka, the entire gully system was active but slightly enhanced at the central area of the study area due to a southward directed shelf transport. In the LGM the export activity was strongly focused in this central area since a low sea level and a direct sediment supply to the shelf edge was provided. During the Holocene until today in contrast, the export activity shifted to the southern part of the study area together with an opposite direction of the main shelf current. This system variability of the last 60 ka is, thus, directly controlled to sediment availability, height of sea level, the oceanographic regime as well as local morphological features on the shelf.


AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013