Author:
Saintilan Nicolas J.,Archer Corey,Maden Colin,Samankassou Elias,Bernasconi Stefano M.,Szumigala David,Mahaffey Zach,West Andy,Spangenberg Jorge E.
Abstract
AbstractThe abundance and types of reef-bearing carbonate platforms reflect the evolution of Devonian climate, with conspicuous microbial-algal reefs in the warm Early and Late Devonian and sponge-coral reefs in the cooler Middle Devonian. A dolomitized Wenlock-Lower Devonian microbial-algal reef-bearing carbonate platform hosts epigenetic copper-cobalt-germanium (Cu-Co-Ge) sulfide mineralization at Ruby Creek-Bornite in the Brooks Range, Alaska. Here, we present rhenium-osmium (Re-Os) radiometric ages and molybdenum and sulfur (δ98/95Mo = +2.04 to +5.48‰ and δ34S = −28.5 to −1.8‰) isotope variations for individual Cu-Co-Fe sulfide phases along the paragenetic sequence carrollite-bornite-pyrite. In the context of a hot, extensional passive margin, greenhouse conditions in the Early Devonian favored restriction of platform-top seawater circulation and episodic reflux of oxidized brines during growth of the carbonaceous carbonate platform. Molybdenum and sulfur isotope data signal the stepwise reduction of hot brines carrying Cu during latent reflux and geothermal circulation for at least ca. 15 million years from the Early Devonian until Cu-Co sulfide mineralization ca. 379–378 million years ago (Ma) in the Frasnian, Late Devonian (weighted mean of Re-Os model ages of carrollite at 379 ± 15 Ma [n = 4]; Re-Os isochron age of bornite at 378 ± 15 Ma [n = 6]). On the basis of petrographic relationships between sulfides and solid bitumen, and the Mo and S isotope data for sulfides, we imply that the endowment in critical metals (e.g., Co, Ge, Re) in the Ruby Creek-Bornite deposit is linked to the activity of primary producers that removed trace metals from the warm Early Devonian seawater and concentrated Co, Ge, and Re in algal-bacterial organic matter in carbonate sediments.
Funder
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
Swiss Federal Institute of Technology Zurich
Publisher
Springer Science and Business Media LLC
Subject
Geochemistry and Petrology,Geophysics,Economic Geology
Reference67 articles.
1. Algeo TJ, Scheckler SE (1998) Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events. Phil Trans Royal Soc London B 353:113–130
2. Andersson B, Godhe A, Filipsson HL, Rengefors K, Berglund O (2020) Differences in metal tolerance among strains, populations, and species of marine diatoms – importance of exponential growth for quantification. Aquat Toxicol 226:105551
3. Bernstein LR, Cox DP (1986) Geology and sulfide mineralogy of the Number One orebody, Ruby Creek copper deposit. Alaska Econ Geol 81:1675–1689
4. Brugger J, Hofmann M, Petri S, Feulner G (2019) On the sensitivity of the Devonian climate to continental configuration, vegetation cover, orbital configuration, CO2 concentration, and insolation. Paleocean Paleoclim 34:1375–1398
5. Chetty D, Frimmel HE (2000) The role of evaporites in the genesis of base metal sulfide mineralization in the Northern Platform of the Pan-African Damara Belt, Namibia: geochemical and fluid inclusion evidence from carbonate wall rock alteration. Miner Deposita 35:364–376
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