Astronomically calibrated ages for geomagnetic reversals within the Matuyama chron

Abstract

We present a magnetostratigraphic record from the western Philippine Sea that is tied to a marine δ18O record for the past 2.14 million years. The ages of geomagnetic reversals were astronomically calibrated by tuning the oxygen isotopic stratigraphy, yielding a chronology for the following subchrons: Matuyama/Brunhes boundary, 781 ± 3 ka (slightly above δ18O Stage 19.3); top of the Santa Rosa polarity interval, 920 ± 2 ka (Stage 23/24); base of the Santa Rosa polarity interval, 925 ± 1 ka (Stage 24); top of the Jaramillo subchron, 988 ± 3 ka (Stage 27); base of the Jaramillo subchron, 1072 ± 2 ka (Stage 31); top of the Cobb Mountain subchron, 1173 ± 4 ka (Stage 35/36); base of the Cobb Mountain subchron, 1185 ± 5 ka (Stage 36); top of the Olduvai subchron, 1778 ± 3 ka (Stage 63/64); base of the Olduvai subchron, 1945 ± 4 ka (Stage 71/ 72); top of the Réunion II subchron, 2118 ± 3 ka (Stage 80/81); and base of the Réunion II subchron, 2133 ± 5 ka (Stage 81). This astronomically calibrated chronology independently confirms the ages of major reversals in recently published astronomically calibrated polarity timescales for the Matuyama chron. It also provides the first astronomically calibrated dates for the lower and upper reversals associated with the Cobb Mountain and Santa Rosa polarity intervals, respectively. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.