PALAEO CLIMATE STUDIES
Toarcian Oceanic
Anoxic Event (Early Jurassic) marks
the beginning of a period
associated with
carbon isotope excursion, significant
levels of biotic extinctions,
severe
global warming, an enhanced
hydrological cycle, and evidence for
widespread
seawater anoxia. The aim of our
project is to link the timing of this
catastrophic event with the large
magmatic eruption in the Karoo basin
in South Africa.
To achieve this goal two fieldworks
have been organized respectively in
the
Karoo basin and in the Neuquen and
Mendoza basins in Argentina.
In collaboration with
the University
of Buenos
Aires
we
successfully managed to gather a large
collection of magmatic rocks and
sedimentary sequences the latest
containing tuff layers. The zircon
dating of these
deposits, conducted at the Department
of Geosciences (Fernando Corfu,
University
of Oslo), confirmed that the South
African igneous
province and the anoxic event recorded
in the Argentinean black shales
are synchronous. Geochemical
analyses
from the logged sequence highlight the
presence of a major
excursion during this period.
Selected reading:
H.A. Leanza, A.
Mazzini, F. Corfu, E.J.
Llambías, H. Svensen, S.
Planke, O. Galland, 2013. The Chachil
Limestone (Pliensbachianeearliest
Toarcian) Neuquén Basin,
Argentina: UePb age calibration and
its significance on the Early Jurassic
evolution of southwestern Gondwana.
Journal of South American Earth
Sciences, 42, 171-185 DOWNLOAD
Mazzini,
A.,
Svensen, H., Leanza, H.A., Corfu, F.
and Planke, S., 2010. Early
Jurassic
shale chemostratigraphy and U-Pb
ages from the Neuquén Basin
(Argentina): Implications for the
Toarcian Oceanic Anoxic Event. Earth
and Planetary Science Letters,
297(3-4): 633-645. DOWNLOAD
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