The tail of the Storegga Slide: Insights from the geochemistry and sedimentology of the Norwegian Basin deposits

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Paull, C. K., Ussler III, W., Holbrook, W. S., Hill, T. M., Haflidason, H., Winters, W., … Lundsten, E. (2010). The tail of the Storegga Slide: Insights from the geochemistry and sedimentology of the Norwegian Basin deposits. Sedimentology, 57(6), 1409-1429. doi:10.1111/j.1365-3091.2010.01150.x
TitleThe tail of the Storegga Slide: Insights from the geochemistry and sedimentology of the Norwegian Basin deposits
AuthorsK. Paull, W. Ussler III, S. Holbrook, M. Hill, H. Haflidason, W. Winters, T. Lorenson, I. Aiello, E. Johnson, E. Lundsten
AbstractDeposits within the floor of the Norwegian Basin were sampled to characterize the deposition from the Storegga Slide, the largest known Holocene-aged continental margin slope failure complex. A 29 to 67 cm thick veneer of variable-coloured, finely layered Holocene sediment caps a homogeneous, extremely well-sorted, poorly consolidated, very fine-grained, grey-coloured sediment section that is >20 m thick on the basin floor. This homogeneous unit is interpreted to represent the uppermost deposits generated by a gravity flow associated with the last major Storegga Slide event. Sediments analogous to the inferred source material of the slide deposits were collected from upslope on the Norwegian Margin. Sediments sampled within the basin are distinguishable from the purported source sediments, suggesting that size sorting has significantly altered this material along its flow path. Moreover, the very fine grain size (3·1 ± 0·3 μm) suggests that the >20 m thick homogeneous unit which was sampled settled from suspension after the turbulent flow was over. Although the turbulent phase of the gravity flow that moved material out into the basin may have been brief (days), significantly more time (years) is required for turbid sediments to settle and dewater and for the new sea floor to be colonized with a normal benthonic fauna. Pore water sulphate concentrations within the uppermost 20 m of the event deposit are higher than those normally found in sea water. Apparently the impact of microbial sulphate reduction over the last ca 8·1 cal ka bp since the re-deposition of these sediments has not been adequate to regenerate a typical sulphate gradient of decreasing concentration with sub-bottom depth. This observation suggests low rates of microbial reactions, which may be attributed to the refractory carbon composition in these re-deposited sediments. © 2010 The Authors. Journal compilation © 2010 International Association of Sedimentologists.
Start page1409
End page1429
SubjectsContinental margin, Deposited sediments, Fine grains, Flow path, Gravity flows, Holocene sediments, Holocenes, Low rates, Microbial reaction, Microbial sulphate reduction, Norwegian margin, Norweigian Basin, Pore waters, Redeposition, Sea floor, Slope failure, Source material, Storegga, Storegga slide, Sulphates, Turbidity current, Turbulent phase, Anoxic sediments, Deposits, Floors, Geochemistry, Ocean currents, Seawater, Sediment transport, Slope stability, Suspensions (fluids), Turbidity, Sedimentology, concentration (composition), deposition, grain size, gravity flow, marine sediment, ocean basin, porewater, sediment chemistry, sediment thickness, sulfate, turbulent flow, Arctic Ocean, Norwegian Margin [Norwegian Sea], Norwegian Sea
NoteCited By (since 1996):1, Rocks & Cores