| Titre | Isotopic evidence for changes in the mercury and zinc cycles during Oceanic Anoxic Event 2 in the northwestern Tethys, Austria |
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| Auteur | Yao, H; Chen, X; Wagreich, M; Grasby, S E ; Liu, S -A; Yin, R; Tostevin, R; Lv, Y; Gu, X; Liu, X; Wang, C |
| Source | Global and Planetary Change vol. 215, 103881, 2022 p. 1-11, https://doi.org/10.1016/j.gloplacha.2022.103881 |
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| Année | 2022 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20220217 |
| Éditeur | Elsevier |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.gloplacha.2022.103881 |
| Media | papier; numérique; en ligne |
| Formats | pdf |
| Région | Tethys |
| Lat/Long OENS | -90.0000 -1.0000 60.0000 -90.0000 |
| Sujets | volcanisme; mercure; zinc; Sciences et technologie; Nature et environnement |
| Illustrations | cartes de localisation; diagrammes; diagrammes |
| Programme | Initiative géoscientifique ciblée (IGC-6) Systèmes minéralisés hydrothermaux |
| Diffusé | 2022 06 24 |
| Résumé | (disponible en anglais seulement)
The Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE 2, ca. 94 Ma) was one of the most extreme carbon cycle and climatic perturbations of the Phanerozoic Eon.
Widespread deposition of organic-rich shales during OAE 2 has been attributed to a rapid rise in atmospheric CO2, global heating, and marine anoxia triggered by intense large igneous province (LIP) volcanism. Here, we present new Hg and Zn elemental
and isotopic analyses from samples spanning OAE 2 in a hemipelagic section from Rehkogelgraben, Austria, which was part of the north-western Tethys. We compare our data to existing records from a range of sites to constrain the relative timing,
magnitude and geographic extent of the perturbation. We find a prominent Hg concentration peak and an overall positive D199Hg excursion, with no correlation between Hg content and organic matter (OM), Mn-Fe-oxyhydroxides, and/or clay minerals. We
interpret this to indicate a terrestrial volcanic origin of Hg. The Hg excursion is coincident with an osmium (Os) isotope excursion, and together, this supports a global period of intense LIP volcanism. The d66Zn record from the Rehkogelgraben
section decreases abruptly by ~0.5 per mil prior to the onset of OAE 2, a change recorded consistently among all reference sections. Combined with the Hg data, we interpret this to result from isotopically light Zn sourced from LIP activity. However,
the second negative excursion in d66Zn during the Plenus Cold Event (PCE), which is recorded in the proto-North Atlantic and adjacent areas and has been attributed to Zn released from OM during re-oxygenation, is not recorded in this section. We
suggest that the cool, oxygenated deep water mass did not invade the Penninic Ocean in the northwestern Tethys. Alternatively, this excursion could be missing in our section due to the presence of carbonate-free sediments during the PCE. After the
PCE, the positive excursion in d66Zn recorded in all sections reveals a recovery of the atmosphere-ocean system. Our findings highlight the significance of spatial and temporal variations in Hg and Zn isotopes during OAE 2. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cet article examine ce que l'on appelle l'événement anoxique océanique Cénomanien-Turonien 2 qui s'est produit il y a 94 millions d'années. Cela
représentait l'une des perturbations climatiques et du cycle du carbone les plus extrêmes des 500 derniers millions d'années, caractérisée par un dépôt généralisé de schistes riches en matières organiques enrichis à de nombreux endroits en minéraux
critiques. Des travaux sont en cours pour mieux comprendre ce qui a conduit à la formation de ces schistes riches en métaux. Les résultats montrent qu'une augmentation rapide du CO2 atmosphérique, du réchauffement global et de l'anoxie marine
déclenchée par un volcanisme intense des grandes provinces ignées, sur la base d'une nouvelle utilisation des analyses élémentaires et isotopiques du mercure et du zinc. Les résultats éclaireront de nouveaux modèles d'exploration pour les ressources
minérales critiques au Canada et dans le monde. |
| GEOSCAN ID | 330546 |
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