The role of the cryosphere in source-to-sink systems

Glacial erosion and sediment production are of interest to diverse scientific communities concerned with the interaction of climatic, tectonic and surface processes that influence the evolution of orogens and with the climatic signals archived in glacigenic strata. We review the current state of knowledge on the generation, transfer, and accumulation of glacigenic sediment from land to sea. We draw from geomorphology, marine geology, geochronology, numerical modeling of surface processes and landscape evolution, and experimental and field observations of glacier erosion and deposition, and the interaction of ice with its bed and the ocean boundary. Our primary goal is to examine glacial systems using a holistic source-to-sink approach, with a focus on describing a) how glacial motion produces sediment, b) how the sediments (sink) record the dynamic nature of glacial systems under different climatic (thermal) regimes, c) the challenges in using the sedimentary record to interpret these dynamics in space and time, and d) the approaches still needed to further our understanding of how ice and associated sediment fluxes respond to climatic and other perturbations. The dynamic state of ice, i.e., the ice flux and ice extent, is defined differently between the source and sink communities, reflecting the challenges of establishing a stratigraphic signal that volumetrically constrains glacigenic sediment production as a function of the ice response to climate. Advances in marine geophysics have greatly assisted our understanding of mass transfer pathways and of former ice extents as a measure of ice dynamics, and have identified the primary depocenters and key lithofacies of glacial sinks. Sediment fluxes associated with the dynamic state of the ice are best constrained where sediment volumes derived from key lithofacies and seismic reflection isopachs can be temporally partitioned, of which there are few examples, rather than from discrete point measures of sediment flux that are subject to sediment transfer biases. Forward numerical modeling of sediment fluxes as a function of ice dynamics agree with observational data at the continental-margin scale, but finer time/space scale ice-dynamic models do not yet recreate observed ice extent or flowpaths. Future source-to-sink work in glaciated systems should focus on refining empirical relationships between ice velocity and sediment production, and expand the application of existing methods to develop sediment volumes and fluxes in known depocenters of former and modern ice streams. (C) 2015 Published by Elsevier B.V.