Integrated magnetobiostratigraphy, paleoclimatic and paleoceanographic inferences of the middle Eocene-Oligocene interval from the Monte Cagnero Section, central Italy
Abstract
The early Eocene to early Oligocene (~55 to 28 Ma) was an important time period for Cenozoic paleoclimatic and paleogeographic evolution. Deep-sea foraminiferal stable isotope records (δ18O and δ13C) indicate a long-term cooling trend that culminated in the Oi-1 glaciation near the Eocene/Oligocene transition at ~34 Ma. In the middle to late Eocene (~49 to 34 Ma), these records also indicate a strong, transient warming event (Middle Eocene Climate Optimum - MECO) at ~40 Ma. The Monte Cagnero sedimentary section, located in the northeastern Apennines near Urbania, Italy, in the Umbria-Marche Basin, is an important middle Eocene-Oligocene section. We use magneto-biostratigraphy and environmental magnetism to study the impact of closure of the Neo-Tethyan gateway on subtropical Eocene circulation to better understand global climate changes during the switch from greenhouse to icehouse conditions. The studied sediments consist of alternating reddish and greenish limestones and marlstones. We undertook high-resolution (~5 cm sample intervals) paleomagnetic and foraminiferal biostratigraphic analyses to construct an integrated age model. The magnetic mineralogy is dominated by a mixture of high- and low-coercivity minerals (probably hematite and magnetite). Environmental magnetic data indicate long-term trends in the concentration, grain-size and composition of magnetic minerals. Moreover, we recognize a magnetic signature that may be related to the MECO event. These new bio-, chemo-, and magnetic results from Monte Cagnero suggest that the section provides a continuous and well-preserved interval for analyzing middle Eocene to lower Oligocene climate. Ongoing analyses are aimed at unraveling paleoclimatic and paleoceanographic changes during a time interval that is not well recorded at other localities.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMGP23C..04J
- Keywords:
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- 1512 GEOMAGNETISM AND PALEOMAGNETISM / Environmental magnetism;
- 1520 GEOMAGNETISM AND PALEOMAGNETISM / Magnetostratigraphy;
- 1605 GLOBAL CHANGE / Abrupt/rapid climate change