The Upper Ypresian and Lutetian in San Pelegrín section (Southwestern Pyrenean Basin): Magnetostratigraphy and larger foraminifera correlation

• Published in: Palaeogeography, palaeoclimatology, palaeoecology palaeoclimatology, palaeoecology, 2013-01, Vol.370, p.13-29
• Main Authors: Rodríguez-Pintó, A., Pueyo, E.L., Serra-Kiel, J., Barnolas, A., Samsó, J.M., Pocoví, A.
• Format: Article
• Language: English
• Subjects: Biostratigraphy; Foraminifera; Larger foraminifera; Magnetostratigraphy; Pyrenean Basin; Shallow Benthic Zones; Ypresian–Lutetian
• ISSN: 0031-0182; 1872-616X
• DOI: 10.1016/j.palaeo.2012.10.029

The current available Shallow Benthic Zones (SBZs) calibration based on larger foraminifera is now being improved for the Paleogene Period. In this work, the San Pelegrín section in the External Sierras, shows new magnetostratigraphic and biostratigraphic information from the Southwestern Pyrenean basin, where the larger thickness of the shallow marine platforms were developed. This environment represents the appropriate frame to calibrate the SBZ scale. Moreover the magnetostratigraphic data can be correlated with biostratigraphic data obtained directly at the same section, avoiding limitations of previous correlations. The San Pelegrín section presents 530m of Ypresian and Lutetian rocks; 169 sampled levels for magnetostratigraphic purposes have been studied, a fact that guarantees the independence and resolution of this record. Thermal and alternating field demagnetizations were carried out to unravel the characteristic remanent magnetization, and the orthogonal diagrams show stable normal and reverse polarity directions. Three pairs of magnetozones were found along the section enabling to define a robust and reliable local polarity sequence correlated with chrons C23, C22, C21n and C20r. The biostratigraphic study distinguished three Shallow Benthic Zones from SBZ11 to SBZ13. The combination of magneto and biochronologic scales is very useful to improve and to accurate the available shallow benthic zone calibration for this time gap, especially for the SBZ11 zone. Now the base of SBZ11 can be located, at least, in 50.96My, because the association is still present at the top of C23n. This data is older than previously thought from existent scales. On the other side, the SBZ11 top falls within chron C22n. The occurrence of a sedimentary hiatus between C22n and C21n prevents an accurate calibration of the SBZ12 top, but our profile proves the relation of SBZ12 with C22n as well. Finally the SBZ13 zone falls within the limits of recent recalibrations (C21n to C20r). ► Ypresian–Lutetian section of 530m with 169 paleomagnetic points and 11 SBZ points ► New magneto-SBZ data calibrated in the same section in optimum facies: shallow marine ► Reliable LPS (chrons C23, C22, C21n, C20r), and SBZ datapoints from SBZ11, 12 &13. ► New calibration data useful to improve available SBZ current scale ► Base of SBZ11: 50.96My, top of SBZ11 and base of SBZ12: C22n, SBZ13: C21n to C20r.