A cold supergene zinc deposit in Alaska: The Reef Ridge case
Notice bibliographique
Résumé
Research Article| November 01, 2015 A cold supergene zinc deposit in Alaska: The Reef Ridge case L. Santoro; L. Santoro 1Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Via Mezzocannone 8, 80134, Napoli, Italy †Current address: Earth Sciences The Natural History Museum, Cromwell Road London SW7 5BD Great Britain; L.Santoro@nhm.ac.uk. Search for other works by this author on: GSW Google Scholar M. Boni; M. Boni 1Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Via Mezzocannone 8, 80134, Napoli, Italy Search for other works by this author on: GSW Google Scholar N. Mondillo; N. Mondillo 1Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Via Mezzocannone 8, 80134, Napoli, Italy Search for other works by this author on: GSW Google Scholar M. Joachimski; M. Joachimski 2GeoZentrum Nordbayern, University of Erlangen–Nuremberg, Schlossgarten 5, 91054, Erlangen, Germany Search for other works by this author on: GSW Google Scholar J. Woodman J. Woodman 3Doyon, Ltd., 1 Doyon Place, Suite 300, Fairbanks, Alaska 99701-2941, USA Search for other works by this author on: GSW Google Scholar Author and Article Information L. Santoro †Current address: Earth Sciences The Natural History Museum, Cromwell Road London SW7 5BD Great Britain; L.Santoro@nhm.ac.uk. 1Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Via Mezzocannone 8, 80134, Napoli, Italy M. Boni 1Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Via Mezzocannone 8, 80134, Napoli, Italy N. Mondillo 1Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Via Mezzocannone 8, 80134, Napoli, Italy M. Joachimski 2GeoZentrum Nordbayern, University of Erlangen–Nuremberg, Schlossgarten 5, 91054, Erlangen, Germany J. Woodman 3Doyon, Ltd., 1 Doyon Place, Suite 300, Fairbanks, Alaska 99701-2941, USA Publisher: Geological Society of America Received: 08 Oct 2014 Revision Received: 25 Feb 2015 Accepted: 23 Mar 2015 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2015 Geological Society of America GSA Bulletin (2015) 127 (11-12): 1534–1549. https://doi.org/10.1130/B31219.1 Article history Received: 08 Oct 2014 Revision Received: 25 Feb 2015 Accepted: 23 Mar 2015 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation L. Santoro, M. Boni, N. Mondillo, M. Joachimski, J. Woodman; A cold supergene zinc deposit in Alaska: The Reef Ridge case. GSA Bulletin 2015;; 127 (11-12): 1534–1549. doi: https://doi.org/10.1130/B31219.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Reef Ridge deposit is a typical supergene “nonsulfide” zinc mineralization, located in the Yukon-Koyukuk region of west-central Alaska (USA). It is hosted in sedimentary rocks of the Farewell terrane, a continental fragment sandwiched between the Siberian and Laurentian cratons during the early Paleozoic. The mineralization occurs in Lower–Middle Devonian shallow-water dolomite of a Paleozoic carbonate platform succession belonging to the Nixon Fork tectonic unit. The mineralization consists of oxidized minerals associated with minor remaining sulfides (pyrite/marcasite and sphalerite). In the oxidation zone, smithsonite is the predominant mineral, mixed with Fe-(hydr)oxides (goethite and hematite).A complete petrographic and mineralogical study was performed. Samples were analyzed by X-ray diffraction, inductively coupled plasma–mass spectrometry and emission spectrometry, energy dispersive scanning electron microscopy, and QEMSCAN® (quantitative evaluation of minerals by scanning electron microscopy). The most abundant mineral in the nonsulfide ore is smithsonite. Similar to other nonsulfide Zn deposits worldwide, the first generation of smithsonite has replaced both primary sphalerite and the host carbonates. A second smithsonite generation precipitated as cement in vugs, cavities, and fractures. Minor zinc amounts also occur in the Fe-(hydr)oxides, and zinc traces have been identified in clay minerals.The carbon and oxygen isotope values of smithsonite at Reef Ridge vary from –0.7 to 2.1‰ relative to Vienna Peedee belemnite (VPDB) and 19.1‰ to 21.9‰ relative to Vienna standard mean ocean water (VSMOW). The δ13C values are similar to those of the host rock, suggesting that the predominant carbon source for smithsonite was the host carbonates, with only a limited contribution from organic carbon. The oxygen isotope ratios of Reef Ridge smithsonite are more depleted in 18O compared to supergene nonsulfides from other parts of the world formed under warm-humid, temperate, or semiarid climates. The oxygen isotope fractionation between water and smithsonite, which relates the δ18O value of the mineralizing solution, the formation temperature of smithsonite, and its δ18O composition, indicates that the δ18O composition of Reef Ridge smithsonite is related to very low formation temperatures (∼10 °C), and strong depletion in 18O of the precipitating waters.The δ18O smithsonite composition, the strong 18O depletion, and the relationship of the formation of the Reef Ridge nonsulfide deposit with the development of the Sleetmute upland surface (which started in the Late Tertiary and continues to the present) indicate that the formation of the Reef Ridge nonsulfide deposit is probably related to cold/humid weathering episodes during a period comprised between Late Tertiary and Holocene.The “traditional” interpretation on the genesis of Zn nonsulfide deposits in warm-humid, temperate, or semiarid conditions should be questioned where other climate zones are indicated. 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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,002 |
| Études des sciences et des technologies | 0,003 | 0,002 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,000 | 0,002 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,005 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».