2019 AAPG Annual Convention and Exhibition:

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Submarine Fans, the Carbon Cycle, and Climate Models


Deep-sea submarine fans are an untapped resource for sedimentary geosciences, in that they provide observational constraints for climate models. Often coupled to very large catchments, the sediment that accumulates in submarine fans is the by-product of continental weathering, an important sink for atmospheric carbon dioxide. However, uncertainty as to the responsiveness of the feedbacks between weathering, erosion and climate is a large source of variability in global carbon and climate models. This is due to a lack of geologic ground-truth, as direct evidence (e.g., paleosols) for weathering over large geographic scales has mostly eroded away. There are two features of submarine fans which together make their detritus a viable proxy for continental processes, and particularly useful to climate models. First, the transfer of material across a catchment and into the deep-sea can occur over geologically short time scales, thus producing a relatively sensitive record of change. At the same time, submarine fans—because of their net-depositional nature—include some of the largest sediment accumulations on Earth and therefore come closer to providing global constraints than most other sedimentary records. Recent work on the largest deep-sea fans, including the Mississippi, Bengal, Veracruz, and Amazon fans, has supplied high resolution compositional trends that tie deep-sea sediment composition to landscape changes. These types of observations from both modern and ancient submarine fans can be used to strengthen climate predictions by providing real-world geologic inputs needed around geosphere-atmosphere feedbacks. The relevance of submarine fans to the carbon cycle has broadened beyond energy, as more and more climate models depend on an earth-systems approach and include long-view predictions past the 21st century.