Magnetostratigraphic dating of the middle Miocene climate change in the continental deposits of the Aragonian type area in the Calatayud-Teruel basin (Central Spain)

Abstract

The exceptionally dense mammalian faunal record of the Aragonian type area in Central Spain shows that an important climate change towards a cooler and more humid climate is recorded during the Neogene Mammal Zone MN 5 [1]. The magnetostratigraphic results from mammal-bearing middle Miocene continental sections in the Aragonian type area indicate that the onset of this climate change, at the MN 4/MN 5 boundary, occurs in the reversed chron C5ACr and has an age of 14.1 Ma, according to the geomagnetic polarity timescale (GPTS) of Cande and Kent [2]. This age is consistent with the age estimate of 14.1–14.05 Ma for the main increase in δ 18O in the marine record [3]. These independent obserbations of time-equivalent cooling in both continental and marine records confirm and accurately date a global cooling event in the middle Miocene. The age of 14.1 Ma for the MN 4/MN 5 boundary is significantly younger than previously recorded in continental timescales [4,5]. This results in a longer duration, by approximately 3 Myr, of the MN 4 zone, which is consistent with the many important faunal changes occurring in MN 4. Furthermore, the MN 5/MN 6 boundary occurs in chron C5ACn (13.8–13.9 Ma) and the MN 6/MN 7–8 boundary in the interval C5Ar.1n-C5Ar.3r (12.7–13.0 Ma).