Biotic response of Tethyan bathyal ostracodes through the Eocene–Oligocene Transition: The composite faunal record from the Massicore and Massignano Global Stratotype Section and Point feature Image

Compilation of relative abundance of Krithe, right:left valve ratios (%RV), and total percent articulation (%ART) in the Massicore (this study) (right panel) with correlation to stable-isotope records at ODP Site 1218 (left panel). Left panel: (A) Site 1218 benthic foraminiferal δ18O. Right panel: compilation of (B) relative abundance of Krithe following PAM, (C) relative abundance of Krithe following DAM, (D–E) right:left valve ratios (RV%) for Krithe and Australoecia with vertical gray bars denoting 50:50 unity, and (F) percent articulation (%ART) for all ostracode taxa in the Massicore. Note: %ART and %RV for Australoecia and Krithe plotted against the PAM.

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Biotic response of Tethyan bathyal ostracodes through the Eocene–Oligocene Transition: The composite faunal record from the Massicore and Massignano Global Stratotype Section and Point (east central Italy)

Benjamin S. Slotnickab and Stephen A. Schellenberga

a Department of Geological Sciences, San Diego State University, San Diego, CA, 92182, USA

b Department of Earth Sciences, Rice University, Houston, TX, 77005, USA

Abstract

The Eocene–Oligocene Transition (EOT) is marked by a double-stepped positive δ18O excursion of ~ 1.3‰ and a deepening of the calcium compensation depth (CCD) interpreted to represent marked Antarctic glaciation and global ocean–atmosphere cooling (i.e., Oi-1 event). A ~ 0.5-m (~ 55–70 kyr) resolution ostracode faunal study of the Massicore, drilled up-section from the Italian Massignano Quarry containing the Eocene–Oligocene Global Stratotype Section and Point (GSSP), revealed a relative increase in Krithe and decreases in faunal evenness and Shannon Index correlative to the Oi-1 event. These transient faunal changes may reflect local water column changes (e.g., export production) or intensified thermohaline flow of cooler deep waters through the paleotethyan seaway. Comparison of these Massicore ostracode faunal data to previously-published Massignano Quarry ostracode faunal data reveals similar relative abundances among common taxa where the study intervals overlap, and thereby provide a more complete Tethyan ostracode record spanning all of C13n and the broader EOT at the GSSP locality.

Marine MicropaleontologyBenjamin S. Slotnick, Stephen A. Schellenberg, Biotic response of Tethyan bathyal ostracodes through the Eocene–Oligocene Transition: The composite faunal record from the Massicore and Massignano Global Stratotype Section and Point (east central Italy), Marine Micropaleontology, ISSN 0377-8398, http://dx.doi.org/10.1016/j.marmicro.2013.03.005