Meteoric 10Be as a tracer of terrestrial denudation in marine sediments: A feasibility study offshore central Chile

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Marine sedimentary successions often preserve long and relatively continuous archives of sediment flux from the continents to the worlds oceans. New quantitative methods using in situ and meteoric cosmogenic isotopes are now available that can be applied to these deposits and will potentially provide modern erosion rates from terrigenous sediment deposited offshore continental margins. In situ 10Be, which records robust spatially averaged erosion rates in onshore fluvial sediment, has so far not been applied to marine records due to the lack of sufficient amounts of sand-sized quartz in marine sediment cores. Meteoric 10Be on the other hand, which carries a signal of erosion from its adsorption to sediment particles, is independent from the particular sample mineralogy and can be conveniently measured on small amounts of fine-grained sediment. However, exchange with seawater and 10Be scavenging in the marine environment necessitates testing of this method. In this study, we will conduct the first small-scale test of tracing the modern terrestrial erosion signal preserved in marine sediments by using cosmogenic nuclide-based 10Be. First, we will determine modern erosion rates for two drainage basins in central Chile, whose sediment is ultimately discharged into the ocean, by using in situ and meteoric 10Be. We will then compare these onshore rates with a record of erosion in the marine realm by measuring meteoric 10Be from surface ocean sediment. This way, we attempt to establish meteoric 10Be as a first-order tracer of modern terrestrial erosion in marine environments offshore central Chile.