UCL logo

UCL Discovery

UCL home » Library Services » Electronic resources » UCL Discovery

Fossil biomass preserved as graphitic carbon in a late Paleoproterozoic banded iron formation metamorphosed at more than 550oC

Papineau, D; DeGregorio, B; Sagar, J; Thorogate, R; wang, J; Nittler, L; Kilcoyne, D; ... Thornton, G; + view all (2019) Fossil biomass preserved as graphitic carbon in a late Paleoproterozoic banded iron formation metamorphosed at more than 550oC. Journal of the Geological Society of London , 176 (4) pp. 651-668. 10.1144/jgs2018-097.

[img] Text
Papine_et_al_2019_jgs2018-097_Accepted.pdf - ["content_typename_Accepted version" not defined]
Access restricted to UCL open access staff until 9 April 2020.

Download (3MB)

Abstract

Metamorphism is thought to destroy microfossils, partly through devolatilization and graphitization of biogenic organic matter. However, the extent to which there is a loss of molecular, elemental, and isotope signatures from biomass during high-temperature metamorphism is not clearly established. We report on graphitic structures inside and coating apatite grains from the ca. 1,850 million years old Michigamme silicate banded iron formation from Michigan, metamorphosed above 550 oC. Traces of N, S, O, H, Ca, and Fe are preserved in this graphitic carbon and X-ray spectra show traces of aliphatic groups. Graphitic carbon has an expanded lattice around 3.6Å, forms microscopic radiating rosettes, and has homogeneous  13C values around -22‰, identical to bulk analyses. Graphitic carbon inside apatite is associated with nanometre-size ammoniated phyllosilicate. Precursors of these metamorphic minerals and graphitic carbon originated from ferruginous clay-rich sediments with biomass. We conclude that graphite coatings and inclusions in apatite grains indicate fluid remobilization during amphibolite facies metamorphism of precursor biomass. This new evidence fills-in observational gaps of metamorphosed biomass into graphite and supports the existence of biosignatures in the highly metamorphosed iron formation from the Eoarchean Akilia Association, which dates from the beginning of the sedimentary rock record.

Type: Article
Title: Fossil biomass preserved as graphitic carbon in a late Paleoproterozoic banded iron formation metamorphosed at more than 550oC
DOI: 10.1144/jgs2018-097
Publisher version: http://dx.doi.org/10.1144/jgs2018-097
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: graphite, metasedimentary, carbon isotopes, biosignature, correlated microscopy.
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: http://discovery.ucl.ac.uk/id/eprint/10070027
Downloads since deposit
2Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item