Title: A paleomagnetic constraint on the Late Cretaceous paleoposition of northwestern Baja California, Mexico
Abstract: We present palaeomagnetic data for Cretaceous sedimentary rocks from the El Rosario formation of northwestern Baja California which imply a northward displacement of 15.0±3.8° and a 30.8±4.2° clockwise rotation for the Baja Peninsula relative to the North American craton since Late Cretaceous time. Paired IRM acquisition, X‐ray diffraction, and Mössbauer spectra indicate that fine‐grained magnetite is the dominant magnetic mineral present, with goethite and other more oxidized phases rare to absent. Biochemical evidence constrains the amount of diagenesis undergone by the sediments. We subjected oriented samples to both progressive alternating field and thermal demagnetization, and in general found univectorial magnetizations, yielding a mean inclination of 44.6° and declination of 5.3° with an α 95 of 2.0°. The corresponding paleolatitude for these values is 26.3±1.6°. Most of the samples were of normal polarity, which is consistent with their deposition within the upper Campanian chron 33N. We collected samples from younger Maastrichtian sediments which yield consistent, reversed directions.
Publication Year: 1989
Publication Date: 1989-06-10
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 25
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