Two-dimensional dust concentration from an outcrop of Last Glacial Maximum ice at Taylor Glacier, Antarctica

Abstract:

An outcrop of ancient glacial ice at Taylor Glacier, Antarctica, provides a unique opportunity to understand dust concentrations in two dimensions - not just downcore as in classical ice cores, but also along-strike in the layers of dust that represent isochronous surfaces. Taylor Glacier hosts dust layers from the Last Glacial Maximum that can be traced visually for several kilometers along strike. The pattern of dust stratigraphy is highly reproducible and allows quick stratigraphic age dating of recognizable features, much as in classical geological field mapping. One striking feature of this record is that Heinrich Stadials are characterized by low dust concentrations, in keeping with prior ice core dust records, but underscored by the visual continuity of the low-dust bands that represent Heinrich Stadials. We hypothesize, following earlier authors, that the low dust is caused by anomalous Patagonian wetness and consequent dust-source reduction, driven by southward shifts of the Earth's thermal equator during Heinrich Stadials. If correct, this hypothesis implies that the bipolar seesaw exists for dust as well as temperature.