Sediment drifts and deep-sea channel systems, Antarctic Peninsula Pacific Margin

Abstract

Twelve sedimentary mounds are identified on the upper continental rise of the Pacific Margin of the Antarctic Peninsula. All these mounds are produced by a varying degree of interaction of along-slope bottom water flow with down-slope turbidity currents. These mounds provide a complete range of intermediates between two end members: the sediment drift and the channel levee. Surface sediments on drift 7 suggest that the mechanisms for the supply and transport of sediment include entrainment of material from turbidity currents within ambient bottom currents, and pelagic settling from the sea surface, including biogenic and glacially derived material. The long-lasting activity of these mechanisms is documented by the data provided by four DSDP and ODP drill sites. Bathymetric and seismic data, both at a large, comprehensive scale and at a small, detailed scale, show the geometry of the sedimentary mounds and their relationships with the adjacent turbidity current channel systems. These data allow the determination of some diagnostic criteria to identify the sediment drifts.

Depositional patterns at Drift 7, Antarctic Peninsula: Along-slope versus down-slope sediment transport as indicators for oceanic currents and climatic conditions

“…This is observed in the seismic lines (see, e.g., Fig. 10 of Rebesco et al, 2002). The general structure shows a steep SW flank and a gentle NE flank.…”

“…5). It has been proposed by Rebesco et al (2002) that turbidity currents here erode and generate channels. Interface M4/M5 shows a local highstand at CDP 5400 against which unit M4 thins.…”

“…Their shape generally is asymmetric with steeper, rougher slopes to the southwest and southeast and gentle slopes to the northeast and northwest. The origin of these sediment bodies is discussed controversially: McGinnis and Hayes (1995) favoured a strong turbiditic (down-slope) influence during mound growth and point out distinct differences between each of the mounds, which indicate differences in sediment supply by turbidity and contouritic currents, whereas Rebesco et al (1996Rebesco et al ( , 1997Rebesco et al ( , 2002 proposed a strong importance of contour-current activity for the development of the mounds and interpreted them as drift bodies.…”

Chapter 5 Cenozoic Climate History from Seismic Reflection and Drilling Studies on the Antarctic Continental Margin

“…Several research groups have conducted seismic studies in the area (Kimura, 1982;Larter andBarker, 1989, 1991b;Anderson et al, 1990;Gamboˆa and Maldonado, 1990;Henriet et al, 1992;Bart and Anderson, 1995, 1996McGinnis and Hayes, 1995;Rebesco et al, 1996Rebesco et al, , 1997Rebesco et al, , 2002Rebesco et al, , 2006McGinnis et al, 1997;Larter et al, 1997;Jin et al, 2002;Jabaloy et al, 2003;Herna´ndez-Molina et al, 2006a). Cenozoic sequences have been drilled at DSDP Site 325 and at multiple sites during ODP Leg 178 (Barker et al, 1999).…”

“…The oldest sediments from ODP Leg 178 are drift deposits at ODP Site 1095, dated at 9.6 Ma, where all cores show glacial influence and sedimentation rates decrease steadily from the late Miocene to the Quaternary. From seismic studies, Rebesco et al (1996Rebesco et al ( , 1997Rebesco et al ( , 2002 suggest that sediment drift deposition began around the middle Miocene, with most growth in the late Miocene. However, Herna´ndez-Molina et al (2004) describe a buried sediment drift of early Miocene age (Fig.…”