Paleowind directions from the magnetic fabric of loess profiles in central Alaska

Two parallel profiles of alternating loess and paleosol horizons from the Halfway House site west of Fairbanks, in central Alaska, were evaluated in terms of their potential for preserving paleowind directions. Combined. the profiles span SPECMAP marine oxygen isotope stages 1-6, approximately the last 150 ka. Our analytical tools consisted of measuring the sample's anisotropy of magnetic susceptibility and characterizing the magnetic mineralogy by multiple approaches. Both primary eolian and secondary reworked magnetic fabrics are recognized along certain intervals of both profiles. Primary eolian fabrics display a horizontal magnetic foliation and a well defined magnetic lineation, corresponding to the paleodirection of sediment transport and deposition. A systematic change in transport direction is observed where long-term prevailing winds appear to shift from a NW-SE to N-S direction during glacial and interglacial periods, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.