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 wellpreserved 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 isotope 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 δ13C 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 tuning, 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 language | English |
|---|---|
| Pages (from-to) | 499-520 |
| Number of pages | 22 |
| Journal | Geological Society of America Bulletin |
| Volume | 131 |
| Issue number | 3-4 |
| DOIs | |
| Publication status | Published - 1 Mar 2018 |
Funding
1Dipartimento di Scienze Pure e Applicate, Università di Urbino, Campus Scientifico “E. Mattei,” 61029 Urbino, Italy 2School of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom 3Université Grenoble Alpes, Université Savoie Mont Blanc, Centre National de Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Institut Français des Sciences et Technologies des Transports (IFSTTAR), et Institut des Sciences de la Terre (ISTerre), 38000 Grenoble, France 4Istituto per l’Ambiente Marino Costiero, Consiglio Nazionale delle Ricerche (IAMC-CNR), Capo Granitola, Via del Mare 3, 91021 Campobello di Mazara (Tp), Italy 5Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Heidelberglaan 2, 3584 CS, Utrecht, The Netherlands 6Istituto di Geoscienze e Georisorse, Consiglio Nazionale delle Ricerche (CNR), Via G. Moruzzi 1, 56124, Pisa, Italy 7Department of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands This research benefited from funds provided by Ministero dell’istruzione, dell’Università e della Ri-cerca (MIUR)–Progetti di Ricerca di Interesse Nazio-nale (PRIN) grant 2010X3PP8J_005 to Galeotti and grant 2010X3PP8J_004 to Sprovieri, by a Ph.D. grant from the Italian Minister for Research to Francescone, by Netherlands Organisation for Scientific Research (NOW) Earth and Life Sciences (ALW) grant (project number 865.10.001) to Lourens, and by Netherlands Earth System Science Center (NESSC) grant 024.002.001 to Schrader and Lourens.
