Workshop explores debris transported by icebergs and paleoenvironmental implications



The only major mechanism for the delivery of sand grains and larger rock particles, known as ice-rafted debris (IRD),into deepocean basins is through transport by floating ice in the form of icebergs and sea ice. For this reason, the earliest occurrence of IRD in Ocean Drilling Program cores obtained from high-latitude continental margins has been used as a key indicator of the inception of large-scale ice-sheet development during the Cenozoic. IRD in Late Quaternary cores from the North Atlantic has also enabled the identification of six sand-rich layers, or “Heinrich Layers” that were deposited from a source in the Hudson Bay drainage area of the last North American ice sheet across some 3000 km of this ocean basin, as far east as the Portuguese margin [Bond et al., 1992]. These layers are thought to have resulted from the melting and release of debris from very large numbers of icebergs that were produced during successive collapses of a 1–2×106-km2 basin within this ice sheet.