EGU General Assembly 2009

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Southern Ocean
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.663.3432; http://meetingorganizer.copernicus.org/egu2009/egu2009-10464-2.pdf

The transient (ca. 500 kyr) climatic warming event at ca. 40 Ma, known as Middle Eocene Climatic Optimum (MECO), significantly interrupted the overall cooling trend of the Middle Eocene. Originally documented in sev-eral deep sea sites at the Southern Ocean (Bohaty and Zachos, 2003), now it appears to be recorded worldwide by pronounced changes of the δ13C and δ18O values and coeval oscillations in global CCD (Tripati et al, 2005). Infor-mation on the planktonic foraminiferal response to this event is so far lacking. Here we present a detailed planktonic foraminiferal analysis of the MECO interval from a marginal basin of the central-western Tethys (Alano di Piave section, northeastern Italy). The expanded and continuous Alano section provides an excellent record of this event and offers an unique opportunity to better understand the role of climate upon calcareous plankton evolution. The initiation of the MECO occurs within magnetochron C18r at ca. 40.5 Ma with minimum δ18O and δ13C values achieved at the base of C18n.2n ca. 40.13 Ma, which are interpreted to represent peak warming conditions. Two sapropel-like, organic-rich intervals coincide with the major change in δ13C record at Alano (Agnini et al., 2007a; Spofforth et al., 2008). The MECO event correlates the E12 (P13) and lower E3 (P14) planktonic foraminiferal zones. The high-resolution quantitative planktonic foraminiferal analysis performed on both>38 µm and>63 µm fraction reveals pronounced and complex changes indicating a strong environmental perturbation that paral-lels the variations of the stable isotope curves. These changes are primarily represented by the marked increase