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Evidence for errors in the geomagnetic polarity time‐scale at 17–15 Ma: 40 Ar/ 39 Ar dating of basalts from the Pacific Northwest, USA.
Author(s) -
Baksi Ajoy K.,
Farrar Edward
Publication year - 1990
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/gl017i008p01117
Subject(s) - basalt , magnetostratigraphy , earth's magnetic field , geology , polarity (international relations) , geomagnetic reversal , paleomagnetism , geophysics , paleontology , physics , magnetic field , chemistry , biochemistry , quantum mechanics , cell
40 Ar/ 39 Ar incremental heating studies have been carried out on whole‐rock basalt samples from the Columbia River Basalt (CRB) and the Steens Basalt, to obtain crystallization ages with a standard error <1%. These high precision, accurate, ages are utilized with the known magnetostratigraphy of the CRB, to test the accuracy of the Early to Middle Miocene section of the geomagnetic polarity time‐scales currently in use. We conclude that these time‐scales underestimate the ages of various chrons within this time range by ∼0.9 m.y.