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Featured researches published by Klaus Michels.


EPIC3Wefer, G., Mulitza, S., Ratmeyer, V. (Eds.): The South Atlantic in the Late Quaternary: Reconstruction of Material Budget and Current Systems. , Berlin Heidelberg New York : Springer-Verlag, p., pp. 375-399, ISBN: 3-540-21028-8 | 2003

Terrigenous Sediment Supply in the Polar to Temperate South Atlantic: Land-Ocean Links of Environmental Changes during the Late Quaternary

Bernhard Diekmann; Dieter K Fütterer; Hannes Grobe; Claus-Dieter Hillenbrand; Gerhard Kuhn; Klaus Michels; Rainer Petschick; Michael Pirrung

Terrigenous sediment parameters in modern sea-bottom samples and sediment cores of the South Atlantic are used to infer variations in detrital sources and modes of terrigenous sediment supply in response to environmental changes through the late Quaternary climate cycles. Mass-accumulation rates of terrigenous sediment and fluxes of ice-rafted detritus are discussed in terms of temporal variations in detrital sediment input from land to sea. Grain-size parameters of terrigenous mud document the intensity of bottom-water circulation, whereas clay-mineral assemblages constrain the sources and marine transport routes of suspended fine-grained particulates, controlled by the modes of sediment input and patterns of ocean circulation. The results suggest low-frequency East Antarctic ice dynamics with dominant 100-kyr cycles and high rates of Antarctic Bottom Water formation and iceberg discharge during interglacial times. In contrast, the more subpolar ice masses of the Antarctic Peninsula also respond to short-term climate variability with maximum iceberg discharges during glacial terminations related to the rapid disintegration of advanced ice masses. In the northern Scotia Sea, increased sediment supply from southern South America points to extended ice masses in Patagonia during glacial times. In the southeastern South Atlantic, changes in regional ocean circulation are linked to global thermohaline ocean circulation and are in phase with northern-hemispheric processes of ice build-up and associated formation of North Atlantic Deep Water, which decreased during glacial times and permitted a wider extension of southern-source water masses in the study area.


Geological Society, London, Memoirs | 2002

The southern Weddell Sea: combined contourite-turbidite sedimentation at the southeastern margin of the Weddell Gyre

Klaus Michels; Gerhard Kuhn; Claus-Dieter Hillenbrand; Bernhard Diekmann; Dieter K Fütterer; Hannes Grobe; Gabriele Uenzelmann-Neben

Abstract Sedimentary processes in the southeastern Weddell Sea are influenced by glacial-interglacial ice-shelf dynamics and the cyclonic circulation of the Weddell Gyre, which affects all water masses down to the sea floor. Significantly increased sedimentation rates occur during glacial stages, when ice sheets advance to the shelf edge and trigger gravitational sediment transport to the deep sea. Downslope transport on the Crary Fan and off Dronning Maud and Coats Land is channelized into three huge channel systems, which originate on the eastern, the central and the western Crary Fan. They gradually turn from a northerly direction eastward until they follow a course parallel to the continental slope. All channels show strongly asymmetric cross sections with well-developed levees on their northwestern sides, forming wedge-shaped sediment bodies. They level off very gently. Levees on the southeastern sides are small, if present at all. This characteristic morphology likely results from the process of combined turbidite-contourite deposition. Strong thermohaline currents of the Weddell Gyre entrain particles from turbidity-current suspensions, which flow down the channels, and carry them westward out of the channel where they settle on a surface gently dipping away from the channel. These sediments are intercalated with overbank deposits of high-energy and high-volume turbidity currents, which preferentially flood the left of the channels (looking downchannel) as a result of Coriolis force. In the distal setting of the easternmost channel-levee complex, where thermohaline currents are directed northeastward as a result of a recirculation of water masses from the Enderby Basin, the setting and the internal structures of a wedge-shaped sediment body indicate a contourite drift rather than a channel levee. Dating of the sediments reveals that the levees in their present form started to develop with a late Miocene cooling event, which caused an expansion of the East Antarctic Ice Sheet and an invigoration of thermohaline current activity.


Marine Geophysical Researches | 2001

Recognition of contour-current influence in mixed contourite-turbidite sequences of the western Weddell Sea, Antarctica

Klaus Michels; Johannes Rogenhagen; Gerhard Kuhn

Sedimentary processes and structures across the continental rise in the western Weddell Sea have been investigated using sediment acoustic and multichannel seismic data, integrated with multibeam depth sounding and core investigations. The results show that a network of channels with associated along-channel ridges covers the upper continental slope. The seismic profiles reveal that the channels initially developed as erosive turbidite channels with associated levees on their northern side due to Coriolis force. Later they were partly or fully infilled, probably as a result of decreasing turbidite activity. Now the larger ones exist as erosive turbidite channels of reduced size, whereas the smaller ones are non-erosive channels, their shape being maintained by contour current activity. Drift bodies only developed where slumps caused a distinctive break in slope inclination on the upper continental rise, which served to initiate the growth of a drift body fed by contour currents or by the combined action of turbidites and contourites. The history of sedimentation can be reconstructed tentatively by correlation of seismo-stratigraphic units with the stages of evolution of the drifts on the western side of the Antarctic Peninsula. Three stages can be distinguished in the western Weddell Sea after a pre-drift stage, which is delimited by an erosional unconformity at the top: (1) a growth stage, dominated by turbidites, with occasional occurrence of slumps during its initial phase; (2) during a maintenance stage turbiditiy-current intensity (and presumably sedimentation rate also) decreased, probably as a result of the ice masses retreating from the shelf edge, and sedimentation became increasingly dominated by contour current activity; and (3) a phase of sheeted-sequence formation. A southward decrease in sediment thickness shows that the Larsen Ice Shelf plays an important role in sediment delivery to the western Weddell Sea. This study shows that the western Weddell Sea has some characteristics in common with the southern as well as the northwestern Weddell Sea: contour currents off the Larsen Ice Shelf have been present for a long time, probably since the late Miocene, but during times of high sediment input from the shelves as a result of advancing ice masses a channel-levee system developed and dominated over the contour-current transport of sediment. At times of relatively low sediment input the contour-current transport dominated, leading to the formation of drift deposits on the upper continental rise. Seaward of areas without shelf ice masses the continental rise mainly shows a rough topography with small channels and underdeveloped levees. The results demonstrate that sediment supply is an important, maybe the controlling factor of drift development on the Antarctic continental rise.


EPIC3 | 2015

AUKRA Benutzungshandbuch - Aquisition und Konturanalyse Rasterelektronenmikroskopischer Aufnahmen

Klaus Michels; Hannes Grobe


Supplement to: Diekmann, B et al. (2004): Terrigenous sediment supply in the polar to temperate South Atlantic: land-ocean links of environmental changes during the late Quaternary. In: Wefer, G; Mulitza, S & Ratmeyer, V (eds.), The South Atlantic in the Late Quaternary: Reconstruction of Material Budget and Current Systems. Springer-Verlag, Berlin, Heidelberg, New York, 375-399, hdl:10013/epic.15597.d001 | 2003

Ice rafted debris distribution in 16 sediment cores from the South Atlantic

Bernhard Diekmann; Dieter K Fütterer; Hannes Grobe; Claus-Dieter Hillenbrand; Gerhard Kuhn; Klaus Michels; Rainer Petschick; Michael Pirrung


Supplement to: Michels, K et al. (2002): The southern Weddell Sea: combined contourite-turbidite sedimentation at the southeastern margin of the Weddell Gyre. In: Stow, D A V; Pudsey, C; Howe, J C; Faugères, J-C & Viana, A R (eds.), Deep-water contourite systems: modern drifts and ancient series, seismic and sedimentary characteristics. Geological Society of London, Memoirs, London, 22, 305-323, hdl:10013/epic.14690.d001 | 2002

Grain size composition of sediment cores from the Weddell Sea, Antarctica

Klaus Michels; Gerhard Kuhn; Claus-Dieter Hillenbrand; Bernhard Diekmann; Dieter K Fütterer; Hannes Grobe; Gabriele Uenzelmann-Neben


In supplement to: Michels, K et al. (2002): The southern Weddell Sea: combined contourite-turbidite sedimentation at the southeastern margin of the Weddell Gyre. In: Stow, D A V; Pudsey, C; Howe, J C; Faugères, J-C & Viana, A R (eds.), Deep-water contourite systems: modern drifts and ancient series, seismic and sedimentary characteristics. Geological Society of London, Memoirs, London, 22, 305-323, hdl:10013/epic.14690.d001 | 2002

Sand fractions of sediment core PS1599-3

Klaus Michels; Gerhard Kuhn; Claus-Dieter Hillenbrand; Bernhard Diekmann; Dieter K Fütterer; Hannes Grobe; Gabriele Uenzelmann-Neben


In supplement to: Michels, K et al. (2002): The southern Weddell Sea: combined contourite-turbidite sedimentation at the southeastern margin of the Weddell Gyre. In: Stow, D A V; Pudsey, C; Howe, J C; Faugères, J-C & Viana, A R (eds.), Deep-water contourite systems: modern drifts and ancient series, seismic and sedimentary characteristics. Geological Society of London, Memoirs, London, 22, 305-323, hdl:10013/epic.14690.d001 | 2002

Ice rafted debris (> 2 mm gravel) distribution in sediment core PS1790-1

Klaus Michels; Gerhard Kuhn; Claus-Dieter Hillenbrand; Bernhard Diekmann; Dieter K Fütterer; Hannes Grobe; Gabriele Uenzelmann-Neben


In supplement to: Michels, K et al. (2002): The southern Weddell Sea: combined contourite-turbidite sedimentation at the southeastern margin of the Weddell Gyre. In: Stow, D A V; Pudsey, C; Howe, J C; Faugères, J-C & Viana, A R (eds.), Deep-water contourite systems: modern drifts and ancient series, seismic and sedimentary characteristics. Geological Society of London, Memoirs, London, 22, 305-323, hdl:10013/epic.14690.d001 | 2002

Sedimentology of core PS1635-1

Klaus Michels; Gerhard Kuhn; Claus-Dieter Hillenbrand; Bernhard Diekmann; Dieter K Fütterer; Hannes Grobe; Gabriele Uenzelmann-Neben


In supplement to: Michels, K et al. (2002): The southern Weddell Sea: combined contourite-turbidite sedimentation at the southeastern margin of the Weddell Gyre. In: Stow, D A V; Pudsey, C; Howe, J C; Faugères, J-C & Viana, A R (eds.), Deep-water contourite systems: modern drifts and ancient series, seismic and sedimentary characteristics. Geological Society of London, Memoirs, London, 22, 305-323, hdl:10013/epic.14690.d001 | 2002

Silt grain size distribution of sediment core PS1367-2

Klaus Michels; Gerhard Kuhn; Claus-Dieter Hillenbrand; Bernhard Diekmann; Dieter K Fütterer; Hannes Grobe; Gabriele Uenzelmann-Neben

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Gerhard Kuhn

Alfred Wegener Institute for Polar and Marine Research

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Hannes Grobe

Alfred Wegener Institute for Polar and Marine Research

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Bernhard Diekmann

Alfred Wegener Institute for Polar and Marine Research

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Dieter K Fütterer

Alfred Wegener Institute for Polar and Marine Research

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Claus-Dieter Hillenbrand

Alfred Wegener Institute for Polar and Marine Research

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Gabriele Uenzelmann-Neben

Alfred Wegener Institute for Polar and Marine Research

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Michael Pirrung

Alfred Wegener Institute for Polar and Marine Research

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Rainer Petschick

Goethe University Frankfurt

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Johannes Rogenhagen

Alfred Wegener Institute for Polar and Marine Research

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Claus-Dieter Hillenbrand

Alfred Wegener Institute for Polar and Marine Research

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