Eocene‐Oligocene paleoceanographic changes in the stratotype section, Massignano, Italy: Clues from rock magnetism and stable isotopes

Abstract

[1] We have conducted high-resolution paleomagnetic and rock magnetic studies, in addition to stable isotope analyses of the Massignano sedimentary section, which is the Global Stratotype Section and Point (GSSP) for the Eocene-Oligocene boundary. Our research builds upon the many past studies of the Massignano section in seeking to understand the timing and nature of the paleoenvironmental variations that occurred during the transition for the Earth's climate system from greenhouse to icehouse. The new paleomagnetic results provide a refined magnetostratigraphy of the section and new age for the Eocene-Oligocene boundary at 33.7 Ma. Abrupt and large alternations in magnetic, concentration, composition, and grain sizes that occur in the high-resolution rock magnetic record are interpreted to be the result of rapid bimodal shifts in deep-sea circulation that affect sediment sources or transport. We speculate that currents flowing through the gateway between the Atlantic and Indo-Pacific Oceans may have turned on and off as the gateway was progressively closing, resulting in the deposition of two different assemblages of magnetic minerals at Massignano.

Late Eocene impact-induced climate and hydrological changes: Evidence from the Massignano global stratotype section and point (central Italy)

“…Following Bice and Montanari (1988) and Lowrie and Lanci (1994), the Popigai and Chesapeake Bay impacts fall within the uppermost part of chron C16n, whereas following Jovane et al (2007), they are more precisely constrained within the upper half of chron C16n.1n. The last impact consistently lies within chron C15n (Figs.…”

“…A new magnetostratigraphic data set, combined with the results of the astronomical tuning of the Massignano section (Jovane et al, 2006), allowed researchers to refi ne the dates for the bio-and chronostratigraphic events previously recorded throughout the succession and to place the EoceneOligocene boundary at 33.7 Ma, 0.2 m.y. younger than in the time scale of Gradstein et al (2004) (Jovane et al, 2007). Based on the magnetostratigraphy provided by Jovane et al (2007) and the numerical ages from Cande and Kent (1995), the mean sedimentation rate of the 4-12 msl segment at Massignano is 0.73 cm/k.y.…”

“…younger than in the time scale of Gradstein et al (2004) (Jovane et al, 2007). Based on the magnetostratigraphy provided by Jovane et al (2007) and the numerical ages from Cande and Kent (1995), the mean sedimentation rate of the 4-12 msl segment at Massignano is 0.73 cm/k.y. Accordingly, this segment would span ~1.1 m.y.…”

“…The Massignano GSSP spans the interval from chron C16n.2n to chron C13n Lowrie and Lanci, 1994;Jovane et al, 2004Jovane et al, , 2006Jovane et al, , 2007 (Fig. 2).…”

“…Iridium profi le is after Montanari et al (1993) and Bodiselitsch et al (2004). Magnetostratigraphy is after (1) Bice and Montanari (1988), (2) Lowrie and Lanci (1994), and (3) Jovane et al (2004Jovane et al ( , 2007.…”