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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 938

Last Page: 938

Title: Erosion of Old Slump-Scar on Nova Scotian Slope and Possible Mid-Slope Depositional Lobe: ABSTRACT

Author(s): Philip R. Hill

Article Type: Meeting abstract


High-resolution seismic profiles and a long-range sidescan sonar (Gloria II) records have been used together to interpret a complex erosional pattern on the Nova Scotian continental slope. A steep uppermost-slope (200 to 500 m depth) is dissected by numerous small gullies which converge to form a single flat-bottomed, erosional channel below 700 m depth. The sidescan record shows these features to be confined to a lobate area, approximately 8 km wide. Seismic profiles outside this area show a smoother topography with greater continuity of parallel subbottom reflectors. The eroded area is interpreted as an old slump-scar which has been secondarily eroded by a gulley-channel system. Cores from the area are compatible with this interpretation.

At about 1,000 m depth, the incised channel cannot be recognized on either the seismic profile or the sidescan record. However, a profile in the predicted path of the channel shows a broad mound, approximately 5 km wide, with a relief of about 20 m. This has a rather similar profile to a suprafan of a submarine fan, with a small channel on the surface, possible buried channels and erosional surfaces in the subbottom. It is suggested that sediment from the channel system has been deposited in this deeper area to form a depositional lobe.

The mid-slope position of this possible depositional system has major implications for interpretation of ancient basin-margin sequences and the later erosion of a slump scar is important in terms of a potential hazard for placing bottom structures.

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