A cold supergene zinc deposit in Alaska: The Reef Ridge case
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".