SPATIAL AND TEMPORAL VARIABILITY OF SEDIMENT FLUX TO BAYS AND FJORDS ALONG A BROAD LATITUDINAL TRANSECT FROM CENTRAL PATAGONIA TO THE ANTARCTIC PENINSULA
We use our estimates of sediment fill volumes to calculate basin-average erosion rate (Ç) for each study area. This was completed by dividing the rock-equivalent volumes by effective drainage basin area and total estimated time span of accumulation for each unit. Erosion rates span two orders of magnitude, from 0.02 mm/yr for Lapeyrère Bay on Anvers Island, Antarctica (~64.5°S), to 0.83 mm/yr for San Rafael Glacier in northern Patagonia (~46.5°S). The latitudinal decrease of millennial Ç along the study transect is ~5% per degree latitude and is interpreted to result primarily from the decrease in temperature and meltwater production with increasing latitude.
Despite variability of terrigenous flux, known variations in climatological and glaciological parameters, and a clear latitudinal trend in Ç, the silt-sized fraction of each individual fjord record (measured using laser particle size analysis of core samples) is surprisingly uniform in post-LGM sediment. Silt size varies among different fjords, however, indicating that bedrock geology is a primary control on grain size. Basins that drain volcanic island landscapes, for example, range from 60 to 75 vol % silt, whereas basins that drain granitic landscapes range from 70 to 80 vol % silt in post-LGM sediment.