TY - JOUR
T1 - Turbidite stacking patterns in salt-controlled minibasins
T2 - Insights from integrated analogue models and numerical fluid flow simulations
AU - Wang, Xiaoxi
AU - Luthi, Stefan M.
AU - Hodgson, David M.
AU - Sokoutis, Dimitrios
AU - Willingshofer, Ernst
AU - Groenenberg, Remco M.
PY - 2017/2/1
Y1 - 2017/2/1
N2 - The sea floor of intraslope minibasins on passive continental margins plays a significant role in controlling turbidity current pathways and the resulting sediment distribution. To address this, laboratory analogue modelling of intraslope minibasin formation is combined with numerical flow simulations of multi-event turbidity currents. This approach permits an improved understanding of evolving flow–bathymetry–deposit interactions and the resulting internal stacking patterns of the infills of such minibasins. The bathymetry includes a shelf to slope channel followed by an upper minibasin, which are separated by a confining ridge from two lower minibasins that compares well with analogous bathymetries reported from natural settings. From a wider range of numerical flow experiments, a series of 100 consecutive flows is reported in detail. The turbidity currents are released into the channel and upon reaching the upper minibasin follow a series of stages from short initial ponding, ‘filling and spilling’ and an extended transition to long retrogradational ponding. Upon reaching the upper minibasin floor, the currents undergo a hydraulic jump and therefore much sediment is deposited in the central part of the minibasin and the counterslope. This modifies the bathymetry such that in the fill and spill stage, flow stripping and grain-size partitioning cause some finer sediment to be transported across the confining ridge into the lower minibasins. Throughout the basin infill process, the sequences retrograde upstream, accompanied by lateral switching into locally formed depressions in the upper minibasin. After the fill and spill stage, significant deposition occurs in the channel where retrograding cyclic steps with wavelengths of 1 to 2 km develop as a function of pulsating flow criticality. These results are at variance with conventional schemes that emphasize sequential downstream minibasin filling through ponding dominated by vertical aggradation. Comparison of these results with published field and experimental examples provides support for the main conclusions.
AB - The sea floor of intraslope minibasins on passive continental margins plays a significant role in controlling turbidity current pathways and the resulting sediment distribution. To address this, laboratory analogue modelling of intraslope minibasin formation is combined with numerical flow simulations of multi-event turbidity currents. This approach permits an improved understanding of evolving flow–bathymetry–deposit interactions and the resulting internal stacking patterns of the infills of such minibasins. The bathymetry includes a shelf to slope channel followed by an upper minibasin, which are separated by a confining ridge from two lower minibasins that compares well with analogous bathymetries reported from natural settings. From a wider range of numerical flow experiments, a series of 100 consecutive flows is reported in detail. The turbidity currents are released into the channel and upon reaching the upper minibasin follow a series of stages from short initial ponding, ‘filling and spilling’ and an extended transition to long retrogradational ponding. Upon reaching the upper minibasin floor, the currents undergo a hydraulic jump and therefore much sediment is deposited in the central part of the minibasin and the counterslope. This modifies the bathymetry such that in the fill and spill stage, flow stripping and grain-size partitioning cause some finer sediment to be transported across the confining ridge into the lower minibasins. Throughout the basin infill process, the sequences retrograde upstream, accompanied by lateral switching into locally formed depressions in the upper minibasin. After the fill and spill stage, significant deposition occurs in the channel where retrograding cyclic steps with wavelengths of 1 to 2 km develop as a function of pulsating flow criticality. These results are at variance with conventional schemes that emphasize sequential downstream minibasin filling through ponding dominated by vertical aggradation. Comparison of these results with published field and experimental examples provides support for the main conclusions.
KW - Cyclic steps
KW - intraslope minibasins
KW - numerical flow modelling
KW - retrogradation
KW - tectonic analogue modelling
KW - turbidity currents
UR - http://www.scopus.com/inward/record.url?scp=85009210960&partnerID=8YFLogxK
U2 - 10.1111/sed.12313
DO - 10.1111/sed.12313
M3 - Article
VL - 64
SP - 530
EP - 552
JO - Sedimentology
JF - Sedimentology
SN - 0037-0746
IS - 2
ER -