Open AccessEocene‐Oligocene paleoceanographic changes in the stratotype section, Massignano, Italy: Clues from rock magnetism and stable isotopes
Author(s) -
Jovane Luigi,
Sprovieri Mario,
Florindo Fabio,
Acton Gary,
Coccioni Rodolfo,
Dall'Antonia Barbara,
DinarèsTurell Jaume
Publication year - 2007
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007jb004963
Subject(s) - geology , stratotype , paleontology , paleomagnetism , magnetostratigraphy , global boundary stratotype section and point , sedimentary rock , rock magnetism , section (typography) , biostratigraphy , stage (stratigraphy) , physics , magnetization , business , quantum mechanics , magnetic field , advertising , remanence
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. Finally, stable isotope ( δ 18 O and δ 13 C) data collected on ostracod valves also suggest significant changes in sea bottom circulation in the Neo‐Tethys Ocean at and about 2 m.y. before the Eocene‐Oligocene boundary.