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A new calibration point for the Late Miocene section of the geomagnetic polarity time scale: 40 Ar/ 39 Ar dating of lava flows from Akaroa Volcano, New Zealand
Author(s) -
Baksi Ajoy K.,
Hoffman Kenneth A.,
Farrar Edward
Publication year - 1993
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 - 10.1029/93gl00332
Subject(s) - earth's magnetic field , geology , lava , volcano , geomagnetic reversal , radiometric dating , magnetostratigraphy , polarity (international relations) , paleomagnetism , late miocene , geophysics , k–ar dating , geomagnetic pole , paleontology , magnetic field , physics , chemistry , quantum mechanics , cell , biochemistry , structural basin
Recent dating of geomagnetic field reversals over the past 2 Ma, by both the radiometric and astrochronologic techniques, indicates that the K‐Ar derived ages for these reversals are too young. We report herein on 40 Ar/ 39 Ar incremental heating study of two geomagnetic field reversals trapped in lavas on Akaroa Volcano, New Zealand, that demonstrate that the K‐Ar derived ages for field reversals at 10–9 Ma are too young by about 7%. The new age for the termination of chron 5, a critical tie point on the geomagnetic polarity time‐scale for late Miocene time, is 9.67±0.11 Ma.