Middle Eocene to Early Oligocene astronomical tuning of the Monte Cagnero section (central Italy)
Abstract
The Middle Eocene to Early Oligocene interval represents a key transition in Earth's palaeoclimate and paleoceanographic history. Benthic δ18O records over this interval indicate a global climate change from warm (greenhouse) to colder (icehouse) conditions, with the rapid expansion of Antarctic continental ice-sheets. Superimposed on this long-term cooling trend, climatic instabilities associated with warming (e.g., Middle Eocene Climatic Optimum - MECO; ~40 Ma), and a prominent cooling event (Oi-1) near the Eocene-Oligocene transition (EOT; ~34 Ma) occurred. Here, we present a new high-resolution magnetic susceptibility (MS) record from 58 to 128 meters stratigraphic level (msl) for the interval spanning magnetic polarity Chrons C18n to C13n at the Monte Cagnero section (Italy). Spectral analysis of the magnetostratigraphically scaled MS time series displays the presence of Milankovitch band cycles. We constructed a preliminary cyclostratigraphic framework based on the identification of the stable long eccentricity and then we astronomically tuned the MS time series to the short eccentricity from the orbital solution. The astronomical tuning allowed us to develop a high-resolution age model for the section. Our new high-resolution timescale shows similar ages and durations for polarity Chrons boundaries compared to other available timescales. It also provides new absolute ages for magneto- and biozones, an estimated duration for the MECO and validates the Eocene-Oligocene boundary from the GSSP at ~33.9 Ma. Finally, the developed timescale may allow further studies at the Monte Cagnero section to have better constrained chronologies within important climatic events such as the MECO and the Oi-1.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGP51B0646K
- Keywords:
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- 1165 Sedimentary geochronology;
- GEOCHRONOLOGY;
- 1520 Magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 4910 Astronomical forcing;
- PALEOCEANOGRAPHY