--> ABSTRACT: Sandy Submarine Braidplains- Potential Deep-Water Reservoir Sands in Subpolar Settings, by R. Hesse, I. Klaucke, S. Khodabakhsh, W. Ryan, and D. J. W. Piper; #91021 (2010)

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Sandy Submarine Braidplains- Potential Deep-Water Reservoir Sands in Subpolar Settings.

HESSE, REINHARD, INGO KLAUCKE, SAEED KHODABAKHSH, WILLIAM RYAN, B. F., and DAVID J. W. PIPER

A sidescan sonar study of the central Labrador Sea revealed the existence of a 550 km long and 120 km wide submarine braidplain which has been fed by high-density sandy turbidity currents most likely resulting from subglacial lake outburst flooding in Hudson Strait. The sidescan sonar imagery displays an intriguing streaky pattern of alternating high- and low-backscatter energy which represents a furrow-and-ridge (erosional) or channel-and-bar (depositional) topography, as the inspection of high-resolution 3.5 kHz seismic profiles shows. The furrows and channels (low backscatter energy) are less than 10 m deep and separated by ridges or bars (high backscatter energy). Some channels terminate in depositional lobes. Individual streaky features are less than a 100 m wide and can be followed up to 10 km downcurrent. This is one of the first examples of a submarine braidplain observed in the deep sea. Positive identification as a braidplain is based on piston cores, which contain massive sand-layers up to 5 m thick and buried under 1-2 m of Holocene to Late Pleistocene (hemi-)pelagic ooze. The shallow channels in the plain are too small to accommodate major flows, which therefore must have been sheet-flow events, which were both erosional and depositional. Radiocarbon ages from the base of the ooze overlying the youngest sand date the latest of these events as slightly older than 10 ky. They might be the submarine counterpart of Heinrich events. Conservative estimates for the discharge volume of individual events are in the range of 10{5}km{3}.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.