Deep-sea foraminiferal stable isotope records (18O) indicate a long-term cooling trend that culminated in the Oi-1 glaciation near the Eocene/Oligocene transition at ~34 Ma. In the late middle Eocene, this trend was interrupted by a strong, transient warming event at ~40 Ma, known as Middle Eocene Climatic Optimum (MECO). The Monte Cagnero sedimentary section, located in the northeasternApennines near Urbania (Italy), in the Umbria-Marche Basin, is an important middle Eocene to lower Oligocene section. We use magnetobiostratigraphy to study the impact of the 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 paleomagnetic, foraminiferal and calcareous plankton 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. These new biostratigraphy and magnetic results from Monte Cagnero suggest that the section provides a continuous and well-preserved interval for analyzing middle Eocene to early Oligocene climate variability.
Middle Eocene to Early Oligocene climate: preliminary magnetobiostratigraphic data from Monte Cagnero section, Central Italy.
LUCIANI, Valeria;
2011
Abstract
Deep-sea foraminiferal stable isotope records (18O) indicate a long-term cooling trend that culminated in the Oi-1 glaciation near the Eocene/Oligocene transition at ~34 Ma. In the late middle Eocene, this trend was interrupted by a strong, transient warming event at ~40 Ma, known as Middle Eocene Climatic Optimum (MECO). The Monte Cagnero sedimentary section, located in the northeasternApennines near Urbania (Italy), in the Umbria-Marche Basin, is an important middle Eocene to lower Oligocene section. We use magnetobiostratigraphy to study the impact of the 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 paleomagnetic, foraminiferal and calcareous plankton 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. These new biostratigraphy and magnetic results from Monte Cagnero suggest that the section provides a continuous and well-preserved interval for analyzing middle Eocene to early Oligocene climate variability.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
