Backwater Hydrodynamic Influence on Avulsion Style and Floodplain Character: Case Study From Mungaroo Formation, Northern Carnarvon Basin
Open Access
- Author:
- Walker, Jasmine
- Graduate Program:
- Geosciences
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 26, 2021
- Committee Members:
- Mark Patzkowsky, Program Head/Chair
Elizabeth Ann Hajek, Thesis Advisor/Co-Advisor
Roman Di Biase, Committee Member - Keywords:
- Seismic
Geomorphology
Channel
Interpretation
Floodplain
Paleo
Delta
Paleo-Deltaic
3D Seismic Data - Abstract:
- Understanding controls on river form and scale is important for sustainably managing modern rivers and floodplains, for reconstructing ancient surface conditions on Earth and other planets, and for predicting the distribution and connectivity of subsurface aquifers and hydrocarbon reservoirs. Recent advances have improved understanding of large, network-scale trends in channel size and form due to, for example, fluvial fan development near sediment sources or backwater hydrodynamics near shorelines. The Triassic Mungaroo Formation – deposits of a continental scale, low-slope fluvio-deltaic system (Northern Carnarvon Basin, offshore Northwest shelf of Australia) – provides a unique opportunity to observe and evaluate upstream-to-downstream changes in a paleo-channel network. Previous work has established strong similarities in Mungaroo channel scale, planform, and sedimentary architecture to those of the Mississippi River (Martin et al., 2018), particularly with respect to downstream changes in channel scale and planform in the zone of backwater hydrodynamic influence on river flow. In this work, I explored connections between channel and floodplain conditions from upstream to downstream in Mungaroo deposits and evaluated how those connections change with, and may be responsible for, shifts in channel planform and paleo-channel mobility. Supply of coarse overbank material to floodplains upstream of the zone of backwater influence is correlated with channels with higher sinuosity and more lateral mobility than channels in regions of backwater influence. These changes are recorded as a shift in the overall style and preservation of floodplain sediments downstream through the Mungaroo system. These results indicate that the coupling between channel and floodplain sedimentation changes downstream as channels encounter the influence of backwater hydrodynamics. This connection is an important control on channel scale, form, and architecture of subsurface channel accumulations.