EAR-PF: A channel-belt scale source of autogenic topography controlling fluvial sedimentation and preservation: Investigation using 3D seismic volumes

Rivers are important resources and are major shapers of the Earth’s surface. Understanding their evolution over time is important with changing climate, yet to understand how rivers evolve over longer than human timescales, we need to examine the sedimentary deposits created by ancient rivers. These deposits record the evolution and migration of rivers over long timescales before being buried. However, while external forces such as changing climate and tectonics can influence the evolution of rivers, there are also internally controlled factors related to spatially variable flow and sediment deposition that may shape river deposits. By repurposing 3D acoustic images collected by the energy industry showing river deposits in Earth’s subsurface, we will examine the deposits of ancient coastal rivers to better understand how these important deposits vary over space and time, and why. The results of this work will help us better understand how and why ancient rivers have modified Earth’s surface, and will help us predict future changes. It has long been recognized that the sedimentary record is often complicated and obscured by time-variable sedimentation, hiatus, and erosion. Exceptions have been recognized primarily at the bedform scale, where local, naturally occurring (autogenic) relief drives rapid sedimentation and preservation. River-channel belts, the sedimentary deposits created by river migration and aggradation over time, are also commonly well preserved at the scale of tens of kilometers. This exceptional preservation is often attributed to external forcings (e.g., subsidence), but autogenic sources of topography at the channel-belt scale have also been recognized and hypothesized to be an important source of autogenic relief. Inter-alluvial-ridge basins may perform this function. To quantify the relative importance of autogenic and allogenic processes in preserving fluvial channel belts, we will use 3D seismic volumes imaging the subsurface of the Gulf of Mexico. Using volumes across the continental shelf, we will map channel belts, build a database of channel-belt geometries, and identify the drivers of their preservation, ultimately tracking the relative importance of autogenic and allogenic processes in preserving channel belts across the Gulf Coast over time. Part of our workflow involves converting analyzed 3D seismic volumes to 3D Numpy arrays, a free, open-source, and easily manipulated dataset, which we will make freely available to make 3D seismic volumes more accessible. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.