|
|
|
|
|
| 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.. |
| 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... |
| Tipo: Text |
|
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00663/77461/82873.pdf |
| |
|
|
| Swanner, Elizabeth D.; Planavsky, Noah J.; Lalonde, Stefan; Robbins, Leslie J.; Bekker, Andrey; Rouxel, Olivier; Saito, Mak A.; Kappler, Andreas; Mojzsis, Stephen J.; Konhauser, Kurt O.. |
| Cobalt (Co) is a bio-essential trace element and limiting nutrient in some regions of the modern oceans. It has been proposed that Co was more abundant in poorly ventilated Precambrian oceans based on the greater utilization of Co by anaerobic microbes relative to plants and animals. However, there are few empirical or theoretical constraints on the history of seawater Co concentrations. Herein, we present a survey of authigenic Co in marine sediments (iron formations, authigenic pyrite and bulk euxinic shales) with the goal of tracking changes in the marine Co reservoir throughout Earthʼs history. We further provide an overview of the modern marine Co cycle, which we use as a platform to evaluate how changes in the redox state of Earthʼs surface were... |
| Tipo: Text |
Palavras-chave: Cobalt; Trace element proxies; Ocean redox; Shale; Iron formation; Pyrite. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00174/28575/26986.pdf |
| |
|
|
|
