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The Kamikatsura event in the Gold Hill loess, Alaska
Author(s) -
Evans Michael E.,
Jensen Britta J. L.,
Kravchinsky Vadim A.,
Froese Duane G.
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl047793
Subject(s) - loess , geology , event (particle physics) , earth science , physical geography , geomorphology , geography , physics , quantum mechanics
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 formed during Oxygen Isotope Stage 19. A systematic perturbation in both declination and inclination occurs ∼1.0–1.5 m below the B‐M boundary. The corresponding virtual geomagnetic 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.