Fossil black smoker yields oxygen isotopic composition of Neoproterozoic seawater

Autor(es):Mostrar menos -

Hodel, F. ^{[1, 2]} ; Macouin, M. ^[2] ; Trindade, R. I. F. ^[1] ; Triantafyllou, A. ^[3] ; Ganne, J. ^[2] ; Chavagnac, V. ^[2] ; Berger, J. ^[2] ; Rospabe, M. ^[2] ; Destrigneville, C. ^[2] ; Carlut, J. ^[4] ; Ennih, N. ^[5] ; Agrinier, P. ^[4]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Geofis, BR-05508090 Sao Paulo - Brazil

^[2] Univ Toulouse, GET, Observ Midi Pyrenees, CNRS, IRD, UPS, F-31400 Toulouse - France

^[3] Univ Nantes, UMR CNRS 6112, Lab Planetol & Geodynam, F-44322 Nantes - France

^[4] Univ Paris Diderot, Univ Sorbonne Paris Cite, Inst Phys Globe Paris, CNRS, UMR 7154, F-75005 Paris - France

^[5] Univ Chouaib Doukkali, Fac Sci, Dept Geol, EGGPG, El Jadida 24000 - Morocco

• Tipo de documento: Artigo Científico
• Fonte: NATURE COMMUNICATIONS; v. 9, APR 13 2018.
• Citações Web of Science: 4

Resumo

The evolution of the seawater oxygen isotopic composition (delta O-18) through geological time remains controversial. Yet, the past delta O-18(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 delta O-18 value of -1.33 +/- 0.98% for the Neoproterozoic bottom seawater supporting a constant oxygen isotope composition through time. We demonstrate that the Ait 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 delta O-18(seawater) and submarine hydrothermal processes were likely similar to present day, Neoproterozoic oceans were 15-30 degrees C warmer on the eve of the Sturtian glaciation and the major life diversification that followed. (AU)

• Processo FAPESP: 16/06114-6 - O Sistema Terra e a evolução da vida durante o Neoproterozoico
• Beneficiário: Ricardo Ivan Ferreira da Trindade
• Modalidade de apoio: Auxílio à Pesquisa - Temático