Morphodynamics of Precambrian rivers
The terrestrial landscapes were colonized by vegetation for only the last 450 Million years, and the advent and diversification of plants is thought to have fundamentally altered the morphology of fluvial systems. The expanding vegetation cover on terrestrial landscapes is associated with the development of well-defined channelization, meandering rivers, and muddy floodplains — all of which have profound influence on the nature of source-to-sink sediment transfer and the evolution of biogeochemical cycles. We are interested in better quantifying the morphodynamics of Precambrian rivers — rivers that once flowed on the Earth’s surface in an environment that was devoid of vegetation. Our current focus is on the Torridonian Sandstone in Scotland, which is a 7 km thick succession of fluvial sandstones that span a significant fraction of Earth’s history (approx. 1.2 Ga to 550 Ma). Using the geometry of river deposits in the Torridonian Sandstone, we aim to constrain the hydraulic and sediment transport conditions of these ancient rivers. These estimates, together with an understanding of sediment transport mechanics and empirical scaling relationships of the self-organization of fluvial systems, may allow us to evaluate the paleo-sediment and water fluxes that shaped these ancient landscapes. Our work has implications for understanding the role of land plants in setting the large-scale morphology and dynamics of fluvial systems, for constraining the size of continental-scale drainage on the Proterozoic supercontinents, and may provide insights into the nature of evolution of fluvial systems on Mars.
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