Provenance and deposition of glacial Lake Missoula lacustrine and flood sediments determined from rock magnetic properties
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Date
2015
Authors
Hanson, Michelle A.
Enkin, Randolph J.
Barendregt, René W.
Clague, John J.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Repeated outburst flooding from glacial LakeMissoula,Montana, affected large areas of Washington duringMarine
Oxygen Isotope Stage 2 (29–14 ka).We present the first high-resolution rock magnetic results from two sites that
are critical to interpreting these outburst floods and that provide evidence of sediment provenance: glacial Lake
Missoula, the source of the floods; and glacial Lake Columbia, where floodwaters interrupted sedimentation.
Magnetic carriers in glacial LakeMissoula varves are dominated by hematite,whereas those in outburst flood sediments
and glacial Lake Columbia sediments aremainly magnetite and titano-magnetite. Stratigraphic variation of
magnetic parameters is consistent with changes in lithology. Importantly, magnetic properties highlight depositional
processes in the flood sediments that are not evident in the field. In glacial Lake Columbia, hematite is
present in fine silt and clay deposited near the end of each flood as fine sediment settled out of the water column.
This signal is only present at the end of the floods because the hematite is concentrated in the finer-grained
sediment transported from the floor of glacial LakeMissoula, the only possible source of hematite, ~240 km away.
Description
Sherpa Romeo green journal. Permission to archive accepted author manuscript.
Keywords
Glacial Lake Missoula , Glacial Lake Columbia , Rock magnetic properties , Glacial outburst floods , Magnetic hysteresis , Thermomagnetic susceptibility
Citation
Hanson, M.A., Enkin, R.J., Barendregt, R.W. & Clague, J.J. (2015). Provenance and deposition of glacial Lake Missoula lacustrine and flood sediments determined from rock magnetic properties. Quaternary Research, 83, 166-177. DOI: https://doi.org/10.1016/j.yqres.2014.09.005