Isotopic Signatures of Carbon in the 'Los Pobres' Graphite Mine, Ronda, Spain

Graphite formation temperatures in the ‘Los Pobres’ mine within the Ronda peridotite, Spain, previously reported to be between 770 and 820 °C, have been reinterpreted based on new temperature measurements using Raman spectroscopy. Additional in situ and bulk stable carbon isotopic measurements and fluid inclusion studies contributed to improved understanding of parts of the graphite formation process. Raman spectroscopy revealed that the formation of the ‘Los Pobres’ graphite extends to temperatures as low as 500 °C, indicating a broader temperature range than previously reported. Stable carbon isotopes and temperature estimates suggest two different crystallization events, followed by a late hydrothermal alteration of the host rock. The first event occurred at temperatures higher than ∼600°C, in which crystalline graphite was formed with a mixed 13C composition as a result of the mixing of two different carbon-bearing sources. The second graphite formation event took place below ∼600°C, within the same system, but with lower purity and crystallinity of the graphite. In the third event, the temperature decreased to less than 550 °C, and hydrothermal fluids altered the host rock, precipitating silica and iron oxides in veins penetrating both the host rock and the deposited graphite.

Broman, CurtUppsala universitet,Paleobiologi (författare)
Ivarsson, MagnusNaturhistoriska riksmuseet,Enheten för paleobiologi,Swedish Museum Nat Hist, Dept Palaeobiol, S-11418 Stockholm, Sweden.;Univ Southern Denmark, Dept Biol, DK-5230 Odense, Denmark. (författare)
Holm, Nils G.Uppsala universitet,Paleobiologi (författare)
Whitehouse, MartinSwedish Museum Nat Hist, Dept Palaeobiol, S-11418 Stockholm, Sweden. (författare)
Nilsson, SaraStockholm Univ, Dept Phys, S-10691 Stockholm, Sweden. (författare)
Geppert, WolfStockholms universitet,Fysikum,Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden.(Swepub:su)wgeppert (författare)
Gervilla, FernandoUniv Granada, Dept Mineral & Petrol, Granada 18002, Spain. (författare)
Uppsala universitetPaleobiologi (creator_code:org_t)

Ingår i:Journal of Petrology: Oxford University Press (OUP)61:40022-35301460-2415

Av författaren/redakt...: Neubeck, Anna; Broman, Curt; Ivarsson, Magnus; Holm, Nils G.; Whitehouse, Mart ...; Nilsson, Sara; visa fler...; Geppert, Wolf; Gervilla, Fernan ...; visa färre...

Om ämnet

Av lärosätet: Stockholms universitet; Naturhistoriska riksmuseet; Uppsala universitet

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