Influence of Basin Slope and Sediment Concentration on Turbidity Current Flow Dynamics and Deepwater Lobe Morphology: Insights From Physical Experiments
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Authors
Chattopadhyay, Arijit
Date
2025-09-04
Type
thesis
Language
eng
Keyword
Deepwater , Unconfined Turbidity Current , Flow Dynamics , Lobe Geometry , Lobe Stacking
Alternative Title
Abstract
The evolution of deepwater turbidite systems is governed by a complex interplay of autogenic flow processes and allogenic controls such as sediment supply and seafloor topography. Despite significant advances in outcrop and subsurface characterization, predictive understanding of how these factors shape lobe geometry, stacking patterns, and facies architecture remains limited. This thesis integrates flume-based physical experiments and subsurface seismic interpretation to investigate the process–response relationships that govern deepwater lobe development.
Three fundamental research questions guide this work: (1) how do basin gradient and sediment concentration influence turbidity current flow dynamics? (2) how do these flow parameters control the spatial architecture and stacking behavior of successive lobes? and (3) Do experimental results correlate with morphodynamic patterns observed in subsurface datasets? These research questions are addressed through physical experiments conducted in a 4 m x 4 m basin using three sediment concentrations (5%, 7.5%, 10%) and three basin gradients (3°, 5°, 7°), while holding sediment type, grain size, discharge, and fluid density constant. For each of the 9 combinations of sediment concentration and basin gradient, a set of 5 currents was generated to build a composite lobe. Two series of experiments were conducted either using a constant gradient or a slope break (inclined-to-flat) geometry, resulting in a total of 18 sets of experiments.
Results demonstrate that slope gradient primarily controls flow acceleration and elongation, while sediment concentration enhances vertical thickening and lateral expansion. Abrupt slope breaks induce strong deceleration, sediment trapping, and a shift from compensational to vertical stacking. Deposits show systematic variations in width, thickness, width to length ratio, and depocenter migration in response to basin gradient and sediment load. Grain-size trends confirm downslope and transverse fining, with localized coarsening near slope breaks.
Seismic analysis of seven composite lobes within the Miocene Moki Formation, Taranaki Basin highlights lobe geometries and stacking styles analogous to experimental results. The alignment between flume-based and seismic-scale observations affirms the predictive power of physical models for interpreting deepwater stratigraphy and reservoir architecture. The findings from this study have direct implications for depositional modeling, facies prediction, and subsurface reservoir characterization in complex bathymetric settings.