Details

Autor(en) / Beteiligte

• Al-Suwaidi, Aisha H.
• Hesselbo, Stephen P.
• Damborenea, Susana E.
• Manceñido, Miguel O.
• Jenkyns, Hugh C.
• Riccardi, Alberto C.
• Angelozzi, Gladys N.
• Baudin, François

Titel

The Toarcian Oceanic Anoxic Event (Early Jurassic) in the Neuquén Basin, Argentina: A Reassessment of Age and Carbon Isotope Stratigraphy

Ist Teil von

• The Journal of geology, 2016-03, Vol.124 (2), p.171-193

Ort / Verlag

Chicago: University of Chicago Press

Erscheinungsjahr

2016

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The Toarcian oceanic anoxic event (T-OAE) is recorded by the presence of globally distributed marine organic carbon–rich black shales and a negative carbon isotope shift, with δ13Corg values as low as −33‰, interrupting an overarching positive excursion. Here we present new biostratigraphic data and high-resolution δ13Corg data from two Southern Hemisphere localities: Arroyo Serrucho in the north and Arroyo Lapa in the south of the Neuquén Basin, Argentina. Previous studies at these localities aimed to provide an accurate numerical age for the T-OAE and characterization of its carbon isotope stratigraphy. The new carbon isotope data and ammonite biostratigraphy presented here from Arroyo Serrucho show the T-OAE to be recorded lower in the section than supposed by previous authors, thus calling into question the published age of the T-OAE in this section. A newly investigated exposure at Arroyo Lapa North shows a complex carbon isotope record with at least three high-amplitude fluctuations in the hoelderi zone (equivalent to the serpentinum zone in northwestern Europe), with δ13Corg values of <−28‰, and two intervening positive isotope excursions, with δ13Corg values around −24‰. At Arroyo Lapa South, the characteristic major stepped negative carbon isotope excursion is recorded, with δ13Corg values of <−30‰ and total organic-carbon contents increasing to 11%; above this level an erosional surface of a submarine channel truncates the section. These new data are globally correlative and unambiguously illustrate the global reach of the T-OAE.