Journal articles
Fossil black smoker yields oxygen isotopic composition of Neoproterozoic seawater
Abstract : The evolution of the seawater oxygen isotopic composition (δ 18 O) through geological time remains controversial. Yet, the past δ 18 O seawater is key to assess past seawater temperatures, providing insights into past climate change and life evolution. Here we provide a new and unprecedentedly precise δ 18 O value of −1.33 ± 0.98‰ for the Neoproterozoic bottom seawater supporting a constant oxygen isotope composition through time. We demonstrate that the Aït Ahmane ultramafic unit of the ca. 760 Ma Bou Azzer ophiolite (Morocco) host a fossil black smoker-type hydrothermal system. In this system we analyzed an untapped archive for the ocean oxygen isotopic composition consisting in pure magnetite veins directly precipitated from a Neoproterozoic seawater-derived fluid. Our results suggest that, while δ 18 O seawater and submarine hydrothermal processes were likely similar to present day, Neoproterozoic oceans were 15-30°C warmer on the eve of the Sturtian glaciation and the major life diversification that followed.
Cited literature [66 references]
https://hal-insu.archives-ouvertes.fr/insu-02178803
Contributor : Eva Fareau <>
Submitted on : Wednesday, July 10, 2019 - 10:56:37 AM
Last modification on : Thursday, October 15, 2020 - 3:14:10 AM
Contributor : Eva Fareau <>
Submitted on : Wednesday, July 10, 2019 - 10:56:37 AM
Last modification on : Thursday, October 15, 2020 - 3:14:10 AM
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