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Modelling and inverting the deep marine sedimentary record to constrain Atlantic Passive Margin landscape evolution

Periodic Reporting for period 1 - STRATASCAPE (Modelling and inverting the deep marine sedimentary record to constrain Atlantic Passive Margin landscape evolution)

Reporting period: 2019-09-12 to 2021-09-11

Coastlines host large human populations, many key natural resources, and important biodiversity hotspots. Given that coastlines are at risk of catastrophic change due to subsidence, sea level rise, increased storm intensity, and other threats, we need to understand how coastlines change through time. An integrated understanding of how Earth’s surface has changed in the geologic past, and how it will change in the future, requires that we understand how sediment is distributed from its sources on continents to the ocean floor. The Atlantic coast of North America is one coastline with a history that is strongly debated, yet there has not been an attempt to use model simulations of Earth surface change to reconstruct the geologic history of this region. One reason for this knowledge gap is the lack of computer models that are able to simulate the deposition of sediment in deep-ocean environments. We will construct a new computer model of surface change at coastlines that includes deep-ocean sediment processes, and use it to better understand the geologic history of the U.S. Atlantic coast. By addressing this knowledge gap, we will improve our ability to understand change at all of Earth’s coastlines, which has important implications for energy research, carbon capture and storage endeavors, and the long-term sustainability of coastal communities. The objectives of this study are to 1) develop a new computer model for deep-ocean sediment processes, 2) test that model by comparing it against observations, and 3) use the new model to extract the geologic history of the U.S. Atlantic coast.
We have developed, as proposed, a new model for sediment processes in the deep ocean environment. This new computer code goes beyond the previous state-of-the-art by applying new mathematical and computational techniques. The model has been disseminated to the scientific community at four conferences and one workshop, and has been released in a public repository. We have also tested the model by applying it to a case study: data on ocean sediments from the western coast of southern Africa. We have used state-of-the-art computing tools to run hundreds of thousands of computer simulations that compare the model to the data and find the model settings that provide the best fit to the real data. Our comparison between model and real data provides new insights into sediment processes in Earth’s oceans. Primarily, it suggests that large portions of sediment delivered by rivers to oceans tend to travel very long distances, past the shallow oceans and into deep ocean basins. We are currently working on using the new model to infer the geologic history of the U.S. Atlantic coast.
This work is contributing to a new view of how sediment processes operate over geologic time. Our work shows, in contrast to previous understanding, that even over the long term the long-distance transport of material from rivers to the ocean floor controls the shape of coastlines and how they change through time. Having had to terminate the project early due to COVID-19 impacts, the third objective will not be completed during the project period. However, using the highly encouraging results from the first two phases of the project, we will continue to address the third objective beyond this project. This work has substantial implications for how we understand change at Earth’s coastlines, and for how we use the record of sediments deposited in the oceans to infer past changes to Earth’s surface. At the largest scales, it is the geologic processes of erosion and sediment transport that determine the distribution of habitable, resource-rich coastlines. Understanding how these regions change through time is critical to keeping people safe in an uncertain future.
Image showing some integral components of the project