The Kamikatsura event in the Gold Hill loess, Alaska

Abstract

[1] As part of a broader geological study of loess/palaesol sequences in Alaska, the paleomagnetism of a section at Gold Hill near Fairbanks has been investigated. Samples were collected at 5 cm intervals through a 5 m loess‐paleosol‐ loess sequence. Detailed alternating field demagnetization of the natural remanent magnetization yields excellent results (average MAD = 2°). The Brunhes‐Matuyama (B‐M) polarity transition is present at the level of the paleosol, which was formedduringOxygenIsotopeStage19.Asystematicperturbation in both declination and inclination occurs ∼1.0–1.5 m belowtheB‐Mboundary.Thecorrespondingvirtualgeomagnetic poles define a track centred on the 60°W meridian from high southerly to equatorial latitudes and back again. This is in very good agreement with results from a sequence of lava flows on the island of Maui that are regarded as a record of the Kamikatsura event. The Alaskan results thus confirm the reality of this geomagnetic feature, and simultaneously provide a firm chronological control point for ongoing geological investigations. Mineral magnetic experiments indicate that the remanence of the Gold Hill loess is dominated by magnetite and/or maghemite, with no subsequent chemical overprinting by hematite and/or goethite. Citation: Evans, M. E., B. J. L. Jensen, V. A. Kravchinsky, and D. G. Froese (2011), The Kamikatsura event in the Gold Hill loess, Alaska, Geophys. Res. Lett., 38, L13302, doi:10.1029/2011GL047793.