Keivy Paraschists (Archean–Early Proterozoic): Nanobacteria and Life

Astafieva, M. M.; Balaganskii, V. V.

doi:10.1134/s0869593818030024

Cited by 3 publications

(1 citation statement)

References 28 publications

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“…Similar isotopic signatures are seen in oils and oil source rocks [39,65,66]. In this light, the recent discovery of forms externally resembling nanobacteria in the schist samples from Shuururta mountain is of interest [67]. It is possible that these organisms contributed to the carbon isotope signatures of some parts of metasedimentary strata in this area.…”

Section: Discussionmentioning

confidence: 59%

Carbon Sources and the Graphitization of Carbonaceous Matter in Precambrian Rocks of the Keivy Terrane (Kola Peninsula, Russia)

et al. 2019

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The Precambrian rocks of the Keivy Terrane reveal five types of carbonaceous matter (CM): Fine-grained, flaky, nest, vein, and spherulitic. These types differ in their distribution character, carbon isotope composition, and graphitization temperatures calculated by the Raman spectra of carbonaceous material (RSCM) geothermometry. Supracrustal rocks of the Keivy Terrane contain extremely isotopically light (δ13CPDB = –43 ± 3‰) carbon. Presumably, its source was a methane–aqueous fluid. According to temperature calculations, this carbon matter and the host strata underwent at least two stages of metamorphism in the west of the Keivy Terrane and one stage in the east. The CM isotope signatures of several samples of kyanite schists (δ13CPDB = –33 ± 5‰) are close to those of oils and oil source rocks, and they indicate an additional carbon reservoir. Thus, in the Keivy territory, an oil-and-gas bearing basin has existed. Heavy carbon (δ13CPDB = −8 ± 3‰) precipitated from an aqueous CO2-rich fluid is derived from either the lower crust or the mantle. This fluid probably migrated from the Keivy alkaline granites into the surrounding rocks previously enriched with “methanogenic” carbon.

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