Environmental magnetism and radiocarbon dating of Burial Lake sediments constrain the timing and magnitude of regional aeolian deposition for the Noatak region of western Arctic Alaska for the last ~37,000 years. Burial Lake (68.43°N, 159.17°W, 21.5 m water depth) is optimally located to monitor regional dust deposition because it is perched above local drainage and isolated from glacial processes. Cores collected in the summer of 2010 were studied through the application of magnetizations and progressive alternating field (AF) demagnetization of u-channel samples, with additional data provided by computed tomography (CT) derived density, hysteresis measurements, isothermal remanent magnetization (IRM) acquisition experiments, organic carbon content, biogenic silica, physical grain size, radiocarbon dating of wood, seeds, and plant macrofossils, point source magnetic susceptibility, and X-ray fluorescence (XRF). With similar magnetic properties to regional Alaskan loess deposits, low coercivity, highly magnetic material deposited during the late-Pleistocene contrasts with a high coercivity, weakly magnetic component found throughout the record, consistent with locally-derived detritus. The relative proportion of low coercivity to high coercivity magnetic material, defined by the S-Ratios, is used to reconstruct the regional input of dust to the basin over time. A four-fold decrease in the low coercivity component through the deglacial transition is interpreted to reflect diminished dust input to the region. Comparisons with potential sources of dust show that the timing of deposition in Burial Lake is largely consistent with general aridity, lack of vegetative cover, and increased windiness, rather than glacial advances or retreats. The influence from subaerial exposure of continental shelves cannot be ruled out as a significant far-field source of dust to interior Alaska during the Last Glacial Maximum (LGM), but is unlikely to have been the sole source, or to have contributed to increased dust in both the early and late Holocene.
Bibliographical noteFunding Information:
This research was supported by the National Science Foundation under grant# NSF-ARC 0909545 . We would like to thank Dr. Nathan Stansell for his help with fieldwork at Burial Lake in 2010, Jacques Labrie and Sylvain Leblanc at ISMER for their assistance with u-channel measurements and data processing, the staff at INRS-ETE for their assistance with CT scanning, Dr. Bernard Housen and Russell Burmester at Western Washington University for the use of their facilities and rock magnetic instruments, and to our many colleagues and friends at CEOAS, particularly Dr. Alan Mix and Dr. Anders Carlson for their help and insight throughout this study. We also thank the editor, and two anonymous reviewers whose comments greatly improved this manuscript.
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- Burial lake
- Environmental magnetism
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