An astronomical polarity timescale for the late middle Miocene based on cyclic continental sequences

• DOI: 10.1029/2002jb001818
• Publication Date: 2003-05-23T18:26:56Z
• Authors: H. Abdul Aziz; W. Krijgsman; F. J. Hilgen; D. S. Wilson; J. P. Calvo
• Keywords: Magnetostratigraphy; Polarity (international relations); Geomagnetic reversal

We present an astronomically tuned polarity timescale for the late middle Miocene based on a cyclic shallow lacustrine/mudflat succession exposed in Orera Composite Section (OCS; Calatayud basin, NE Spain). Spectral analysis and band‐pass filtering of high‐resolution carbonate color reflectance records depth domain reveal changes with different cycle lengths, which correspond to lithological alternations observed field. An initial age model was constructed by calibrating OCS magnetostratigraphy geomagnetic Cande Kent [1995] . Subsequent spectral proxy time reveals periodicities close 23, 41, 400 kyr and, lesser extent, 100 kyr, supporting astronomical origin sedimentary cyclicity OCS. established new calibration Laskar et al. [1993] (La93) solution tuning cycles target curves. Cross‐spectral results series followed remarkably good in‐phase relation precession obliquity despite presumed uncertainty 20–40 some short intervals. Our provides ages subsequently reversals interval between 12.9 10.6 Ma. Comparison shows that reversal are older 80 kyr. This discrepancy decreases increasing 50–60