Deep-sea fans: tapping into Earth's changing landscapes

Abstract

ABSTRACT Deep-sea fan sediments carry physical and chemical signatures that reflect the conditions under which their native landscapes evolved. Fans are long-lived, strongly net-depositional heaps of terrigenous debris, in some cases directly connected to a major river catchment. Here we use recent findings from deep-sea fans around the world to reason that modern fans might be our most continuous record of Cenozoic landscape change over large geographic scales. We opt for the use of multiple signatures that indicate major shifts in composition, because this approach avoids the problems inherent to measuring sediment flux alone. We emphasize the importance of looking across grain size, in particular at the clay fraction, the fastest carrier of sedimentary signals. Highlighted cases show the range of environmental signals preserved in deep-sea fans, observed over millennial and longer time scales, and how these signals help us understand the climate–surface interactions important to the carbon cycle. Revisiting legacy core with new techniques, in addition to future drilling campaigns, can provide the observational constraints needed to fill recognized gaps in climate models and landscape–erosion projections.