Early Jurassic climatic trends in the south-Tethyan margin
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Version: Final published version
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UNIL restricted access
State: Public
Version: Final published version
License: All rights reserved
Serval ID
serval:BIB_2A22F9B608A8
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Early Jurassic climatic trends in the south-Tethyan margin
Journal
Gondwana Research
ISSN
1342-937X
Publication state
Published
Issued date
01/2020
Peer-reviewed
Oui
Volume
77
Pages
67-81
Language
english
Abstract
The Early Jurassic period was characterized by extreme environmental changes, as reflected by major global carbon isotope anomalies and abrupt changes in oxygen isotope and elemental records of marine organisms. Available data suggest an overall warm Early Jurassic climate interrupted by periods of severe cooling, with a climatic optimum during the early Toarcian. Available geochemical studies, however, have mainly focused on the northern margin of the Tethys Ocean, so that the palaeogeographic extent of these environmental perturbations, latitudinal palaeotemperature gradients and climate belt boundaries remain poorly constrained. Here we report the first stable isotope records of brachiopod shells (δ13C and δ18O values) from the Upper Sinemurian-Middle Toarcian interval in the southern margin of the Tethys Ocean (northwest Algeria). These data were used to better constrain the palaeoenvironmental evolution of the North Gondwana margin during the Early Jurassic, which likely played an important role on supra-regional climate. The diagenetic history of the analysed brachiopod shells was monitored using scanning electron microscopy, and elemental (manganese and strontium) compositions. The brachiopod δ13C and δ18O data show very similar trends as those reported for various Tethyan regions, and record negative carbon and oxygen isotope excursions near the Sinemurian–Pliensbachian and Pliensbachian–Toarcian transitions and during the Toarcian oceanic anoxic event (T-OAE). Despite these similarities, the carbon and oxygen isotope records are systematically offset towards more positive δ13C values (average +0.5‰) and more negative δ18O values (−1.0‰) compared to those obtained from sites of higher palaeolatitudes in the northern Tethyan margin. These offsets suggest a spatial heterogeneity in the stable isotope composition of dissolved inorganic carbon in the Early Jurassic Ocean and a marked latitudinal temperature gradient between the southern and northern margins of the Tethys.
Keywords
Carbon and oxygen stable isotopes, Early Jurassic, NW Algeria, Palaeoclimate
Web of science
Open Access
Yes
Create date
28/09/2019 8:20
Last modification date
18/05/2024 5:58