Sediment waves with a biogenic twist in Pleistocene cool water carbonates, Great Australian Bight

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doi: 10.1016/j.margeo.2010.09.009
Author(s): Anderskouv, K.; Surlyk, F.; Huuse, M.; Lykke-Andersen, H.; Bjerager, M.; Tang, C. D.
Author Affiliation(s): Primary:
University of Copenhagen, Department of Geography and Geology, Copenhagen, Denmark
Other:
University of Manchester, United Kingdom
Aarhus University, Denmark
Geological Survey of Denmark and Greenland, Denmark
DONG, Denmark
Volume Title: Marine Geology
Source: Marine Geology, 278(1-4), p.122-139. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. 89 refs.; illus., incl. sects., 2 tables, sketch maps
Summary: Sediment waves composed of fine-grained carbonate ooze with in-place bryozoans are a characteristic element of the Pleistocene of the Great Australian Bight (GAB). The low-amplitude and strongly elongate sediment waves are up to 10km long, 1km wide, 40m high, and oriented sub-parallel to contours immediately off the shelf-slope break. They are asymmetrical, showing up-slope migration, and mainly occur in trains. The sediment waves were drilled during ODP leg 182 in 1998, and were interpreted as biogenic reef mounds. New high-quality seismic and multibeam bathymetry data were acquired on the Galathea 3 expedition in 2006, allowing description of the morphology and internal architecture of the sediment waves in unprecedented detail, leading to an alternative interpretation of their formation. Most sediment waves were initiated by preferential deposition on the landward side of irregular erosion surfaces. Sediment wave accretion took place under the influence of density driven currents, which decelerated up the landward-dipping flanks and accelerated down the seaward-dipping flanks of the sediment waves. The currents are interpreted as dense water cascades formed by summer evaporation and strong winter cooling by analogy with oceanographic processes in the present day GAB. The lithological composition varied with climate and sea level, but sediment wave formation did not. Sediment waves formed and accreted during both glacials and interglacials in contrast to the previous interpretations, which involved growth in glacial periods only. Bryozoans influenced the depositional environment by adding sediment, trapping fine-grained particles, and stabilizing the muddy sea floor. This caused the sediment waves to gain a more prominent sea floor relief than most muddy siliciclastic sediment waves formed by similar depositional processes. The interpretation of the sediment waves as purely biogenic build-ups is rejected, and the sediment waves are most appropriately described as biogenically-influenced sediment waves. Abstract Copyright (2010) Elsevier, B.V.
Year of Publication: 2010
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Acoustical methods; Bathymetry; Bedding plane irregularities; Bioclastic sedimentation; Biogenic processes; Bottom features; Bryozoa; Carbonate sediments; Cenozoic; Clastic sediments; Cores; Currents; Density currents; Depositional environment; Geophysical methods; Geophysical profiles; Geophysical surveys; Glacial environment; Glaciomarine environment; Great Australian Bight; Indian Ocean; Interglacial environment; Invertebrata; Leg 182; Marine environment; Marine sediments; Mounds; Multibeam methods; ODP Site 1127; ODP Site 1129; ODP Site 1131; Ocean Drilling Program; Ocean currents; Ocean floors; Ooze; Paleoclimatology; Pleistocene; Quaternary; Sand waves; Sedimentary structures; Sedimentation; Sediments; Seismic methods; Seismic profiles; Surveys
Coordinates: S332127 S331700 E1282853 E1282852
Record ID: 2011022142
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands