Miocene to Recent contourite drifts development in the northern Weddell Sea (Antarctica)

• Published in: Global and Planetary Change
• Main Authors: Maldonado, Andrés, Barnolas, Antonio, Bohoyo, Fernando, Escutia, Carlota, Galindo Zaldívar, Jesús, Hernández-Molina, Francisco J., Jabaloy, Antonio, Lobo, F. J., Nelson, C. Hans, Rodríguez-Fernández, José, Somoza, Luis, Vázquez, Juan Tomás
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2005
• Subjects: Contourite drifts; Antarctic paleoceanography; Weddell Gyre; Glaciations; Antarctic; Weddell; Weddell Sea; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10261/18739; https://doi.org/10.1016/j.gloplacha.2004.09.013

31 pages, 13 figures, 1 table. Multichannel and high-resolution seismic profiles complemented with swath bathymetry show a variety of contourite deposits in the northern Weddell Sea resulting from the interaction between bottom currents and the seafloor physiography. Seven types of contourite drifts are identified based on the seismic signature, reflector configuration and geometry of the depositional bodies. Giant elongated–mounded drifts are widespread in the area and associated with major channelized contour currents that flow at the base of large ridges. Thick basement/tectonic drifts result from the seafloor disruptions of the currents caused by the irregularities of the near-surface basement morphology. Sheeted drifts occur under the main core of the Weddell Gyre and also in areas of the abyssal plain away from the main flows. Various types of drifts in-fill depressions or are plastered against steep bathymetric ridges that intersect contour currents. The regional distribution of the drifts is mainly controlled by the physiography of the basin and the confined or unconfined nature of the bottom-current flows. The northern Weddell Sea is a region dominated by contourite processes and thus provides an area to compare contourite drifts with turbidite systems. The giant elongated–mounded drifts have a net asymmetry of the body, in contrast to turbidite channel–levee complexes that develop levees on each side of an axial turbidite channel. The basement/tectonic drifts prograde parallel to the main flow and are plastered following the irregularities of the basement unlike turbidite deposits. Other drifts, in contrast, show internal reflector characteristics similar to turbidite systems, such as the sheeted drifts. In these cases, however, the associations of turbidite and drift deposits are different. The giant elongate-mounded drifts are stacked along the margins and elongate or transverse drift sequences are observed in the basin centre of confined basins. In the unconfined setting, the drifts are normally ...