Data/hora: 26/07/2024 22:09:32

Provedor de dados: 	Institutional Archive of Ifreme (ArchiMer)	
País: 	France	
Título: 	Palaeoproterozoic oxygenated oceans following the Lomagundi-Jatuli Event	
Autores: 	Mand, Kaarel; Lalonde, Stefan; Robbins, Leslie J.; Thoby, Marie; Paiste, Kart; Kreitsmann, Timmu; Paiste, Paarn; Reinhard, Christopher T.; Romashkin, Alexandr E.; Planavsky, Noah J.; Kirsimae, Kalle; Lepland, Aivo; Konhauser, Kurt O.	
Data: 	2020-04	
Ano: 	2020	
Resumo: 	The oceans probably remained well-oxygenated for millions of years after the Palaeoproterozoic Lomagundi-Jatuli Event, according to high concentrations and isotope signatures of redox-sensitive metals in the 2-billion-year-old Zaonega Formation, Russia. The approximately 2,220-2,060 million years old Lomagundi-Jatuli Event was the longest positive carbon isotope excursion in Earth history and is traditionally interpreted to reflect an increased organic carbon burial and a transient rise in atmospheric O-2. However, it is widely held that O-2 levels collapsed for more than a billion years after this. Here we show that black shales postdating the Lomagundi-Jatuli Event from the approximately 2,000 million years old Zaonega Formation contain the highest redox-sensitive trace metal concentrations reported in sediments deposited before the Neoproterozoic (maximum concentrations of Mo = 1,009 mu g g(-1), U = 238 mu g g(-1) and Re = 516 ng g(-1)). This unit also contains the most positive Precambrian shale U isotope values measured to date (maximum U-238/U-235 ratio of 0.79 parts per thousand), which provides novel evidence that there was a transition to modern-like biogeochemical cycling during the Palaeoproterozoic. Although these records do not preclude a return to anoxia during the Palaeoproterozoic, they uniquely suggest that the oceans remained well-oxygenated millions of years after the termination of the Lomagundi-Jatuli Event.	
Tipo: 	Text	
Idioma: 	Inglês	
Identificador: 	https://archimer.ifremer.fr/doc/00663/77461/82873.pdf

DOI:10.1038/s41561-020-0558-5

https://archimer.ifremer.fr/doc/00663/77461/	
Editor: 	Nature Publishing Group	
Formato: 	application/pdf	
Fonte: 	Nature Geoscience (1752-0894) (Nature Publishing Group), 2020-04 , Vol. 13 , N. 4 , P. 302-306	
Fonte: 	info:eu-repo/semantics/openAccess

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