A 9 million-year-long astrochronological record of the early– middle Eocene corroborated by seafloor spreading rates

Federica Francescone, Vittoria Lauretano, Claire Bouligand, Matteo Moretti, Nadia Sabatino, Cindy Schrader , Rita Catanzariti, Frits Hilgen, Luca Lanci, Antonio Turtù, Mario Sprovieri, Lucas J. Lourens, Simone Galeotti

Research output: Contribution to journalArticle (Academic Journal)peer-review

4 Citations (Scopus)

Abstract

The early–middle Eocene (ca. 56–41 Ma) is recorded in the pelagic Scaglia Rossa and Variegata Formations of the Umbria-Marche Basin (central Italy). Geochemical and magnetostratigraphic alignment between the Bottaccione section (Gubbio, central Italy) and the Smirra core (Cagli, central Italy) allows us to generate a continuous and well- preserved new record that, combined with previously published data from the same area, creates a continuous high-resolution record from the Paleocene-Eocene thermal maximum (ca. 56 Ma) to the lower part of chron C21n. Comparison with carbon iso- tope records from Ocean Drilling Program Sites 1258 and 1263 reveals a satisfactory match, providing further evidence of the global significance of the long-term trend and superposed perturbations captured by the d13C records. The identification of astronomically forced geochemical cycles allows us to develop a 405 k.y. tuned age model, thereby extending the astrochronology from ca. 56.0 to ca. 47.5 Ma. Marine magnetic anomaly profiles from major oceanic basins characterized by high seafloor spreading rates were used to independently test the astronomical polarity time scale associated with our tun- ing, as well as other polarity time scales. Our age model suggests the existence of periods of relatively constant seafloor spreading rates separated by rapid changes, while the other time scales generate more gradual variations and also include large and short-term deviations in spreading rates that occur simultaneously in different oceanic basins, implying errors in polarity reversal ages. The Umbria- Marche age model further contributes to the closure of the middle Eocene gap in the astronomical time scale
Original languageEnglish
Pages (from-to)499-520
Number of pages22
JournalGSA Today
Early online date1 Nov 2018
DOIs
Publication statusE-pub ahead of print - 1 Nov 2018

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