Astronomical Tuning and Duration of Three New Subchrons (C5r.2r‐1n, C5r.2r‐2n and C5r.3r‐1n) Recorded in a Middle Miocene Continental Sequence from NE Spain

摘要: In the astronomically tuned Miocene continental Orera Composite Section (OCS) of NE Spain, one short interval and two single sample levels normal polarity were found. The low sampling resolution inhibited determination whether these intervals represent remagnetization, reversal excursions or even subchrons. We have sampled with high resolution, to determine their authenticity, astronomical duration. Rock magnetic analysis indicates that main minerals in studied rocks are magnetite (fine-grained) hematite. Furthermore, a positive correlation is observed between rock parameters lithology. Geochemical also reveals strong relation concentrations elements Al, Ca Mg lithologic changes. To characterize sedimentary environment possibly identify diagenetic influence on acquisition natural remanent magnetization (NRM), multivariate classification techniques performed using both geochemical variables. conclude intervals-denoted as OCS-1, OCS-2 OCS-3-are not overprints artefacts processes, but real features geomagnetic field. OCS-1 has an estimated duration 26 kyr, corresponds cryptochron C5r.2r-1 identified at ODP Site 845. argue it must now be termed subchron C5r.2r-ln. 15 although does clearly show pair reversals, denoted C5r.2r-2n. Finally, OCS-3 9 full reversals considered C5r.3r-1n.