Control of sediment supply, palaeoceanography and morphology on late Quaternary sediment dynamics at the Galician continental slope

2012 ◽  
Vol 32 (4) ◽  
pp. 313-335 ◽  
Author(s):  
Vera B. Bender ◽  
Till J. J. Hanebuth ◽  
Anxo Mena ◽  
Karl-Heinz Baumann ◽  
Guillermo Francés ◽  
...  
Keyword(s):  
Continental Slope ◽  
Late Quaternary ◽  
Sediment Dynamics ◽  
Sediment Supply ◽  
Quaternary Sediment

scholarly journals Time-integrated 3D approach of late Quaternary sediment-depocenter migration in the Tagus depositional system: From river valley to abyssal plain

2016 ◽  
Vol 153 ◽  
pp. 192-211 ◽  
Author(s):  
Geert-Jan Vis ◽  
Cornelis Kasse ◽  
Dick Kroon ◽  
Jef Vandenberghe ◽  
Simon Jung ◽  
...  
Keyword(s):  
Late Quaternary ◽  
River Valley ◽  
Abyssal Plain ◽  
Quaternary Sediment ◽  
Depositional System

Stratigraphy and palaeoenvironmental interpretation of late Quaternary colluvial slope deposits in southern Africa

2021 ◽  
Author(s):  
J. Knight
Keyword(s):  
Southern Africa ◽  
Land Surface ◽  
Late Quaternary ◽  
Ecological Factors ◽  
Surface Instability ◽  
Sediment Supply ◽  
Spatial And Temporal Patterns ◽  
Catchment Scale ◽  
Accommodation Space ◽  
Slope Sediment

Abstract Slope and lowland sediment systems throughout southern Africa are dominated by the presence of colluvium with interbedded palaeosols and hardground duricrusts. These sediments correspond to phases of land surface instability and stability, respectively, during the late Quaternary. This study examines the stratigraphy and environmental interpretation of slope sediment records from specific sites in southern Africa for the period of marine isotope stages (MIS) 6 to 1 (~191 ka to present), informed by theoretical ideas of the dynamics of slope systems including sediment supply and accommodation space. Based on this analysis, phases of land surface instability and stability for the period MIS 6 to 1 are identified. The spatial and temporal patterns of land surface conditions are not a simple reflection of climate forcing, but rather reflect the workings of slope systems in response to climate in addition to the role of geologic, edaphic and ecological factors that operate within catchment-scale sediment systems. Considering these systems dynamics can yield a better understanding of the usefulness and limitations of slope sediment stratigraphies.

Late Quaternary sedimentation on the southwestern Scotian Slope, eastern Canada: relationship to glaciationGeological Survey of Canada Contribution 20070176.

2008 ◽  
Vol 45 (3) ◽  
pp. 267-285 ◽  
Author(s):  
Thian Hundert ◽  
David J.W. Piper
Keyword(s):  
Late Quaternary ◽  
Sediment Cores ◽  
Sediment Supply ◽  
Scotian Shelf ◽  
Eastern Canada ◽  
Glacial Retreat ◽  
Air Gun ◽  
Continental Slopes ◽  
History Of ◽  
Seismic Reflection Profiles

The sedimentary record on continental slopes has the potential to preserve a record of glacial retreat on the adjacent continental shelf. The glacial history of the southwestern part of the Scotian Shelf is poorly known. Air-gun and high-resolution sparker profiles and numerous sediment cores up to 10 m long have been used to determine the character of sedimentation on the southwestern Scotian Slope since the last glacial maximum (LGM). Seismic-reflection profiles show that glacial till was deposited at shallow depths on the upper continental slope, and correlation to dated piston cores farther downslope show that this till dates from the LGM. Slope sedimentation at this time was dominated by local ice and deposited as plume fallout and turbidites. Progressively increasing importance of red-brown sediment derived from glacial supply to Laurentian Channel indicates retreat of ice from the shelf edge and diminishing supply of proglacial sediment from the calving embayment in the mid-Scotian Shelf. With the termination of distal proglacial sediment supply, the sedimentation rate diminished rapidly and hemipelagic sedimentation prevailed through the Holocene.

Numerical modeling of fluvial strath-terrace formation in response to oscillating climate

2002 ◽  
Vol 114 (9) ◽  
pp. 1131-1142 ◽  
Author(s):  
Gregory S. Hancock ◽  
Robert S. Anderson
Keyword(s):  
Sediment Transport ◽  
Late Quaternary ◽  
Water Discharge ◽  
Temporal Variations ◽  
Sediment Supply ◽  
River Systems ◽  
Climatic Fluctuations ◽  
Wind River Basin ◽  
Sinusoidal Input ◽  
Lateral Erosion

Abstract Many river systems in western North America retain a fluvial strath-terrace rec ord of discontinuous downcutting into bedrock through the Quaternary. Their importance lies in their use to interpret climatic events in the headwaters and to determine long-term incision rates. Terrace formation has been ascribed to changes in sediment supply and/or water discharge produced by late Quaternary climatic fluctuations. We use a one-dimensional channel- evolution model to explore whether temporal variations in sediment and water discharge can generate terrace sequences. The model includes sediment transport, vertical bedrock erosion limited by alluvial cover, and lateral valley-wall erosion. We set limits on our modeling by using data collected from the terraced Wind River basin. Two types of experiments were performed: constant- period sinusoidal input histories and variable-period inputs scaled by the marine δ18O rec ord. Our simulations indicate that strath-terrace formation requires input variability that produces a changing ratio of vertical to lateral erosion rates. Straths are cut when the channel floor is protected from erosion by sediment and are abandoned—and terraces formed—when incision can resume following sediment-cover thinning. High sediment supply promotes wide valley floors that are abandoned as sediment supply decreases. In contrast, wide valleys are promoted by low effective water discharge and are abandoned as discharge increases. Widening of the valley floors that become terraces occurs over many thousands of years. The transition from valley widening to downcutting and terrace creation occurs in response to subtle input changes affecting local divergence of sediment-transport capacity. Formation of terraces lags by several thousand years the input changes that cause their formation. Our results suggest that use of terrace ages to set limits on the timing of a specific event must be done with the knowledge that the system can take thousands of years to respond to a perturbation. The incision rate calculated in the field from the lowest terrace in these systems will likely be higher than the rate calculated by using older terraces, because the most recent fluvial response in the field is commonly downcutting associated with declining sediment input since the Last Glacial Maximum. This apparent increase in incision rates is observed in many river systems and should not necessarily be interpreted as a response to an increase in rock-uplift rate.

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