Fossil biomass preserved as graphitic carbon in a late paleoproterozoic banded iron formation metamorphosed at more than 550°C

Beitrag in einer Fachzeitschrift


Details zur Publikation

Autorinnen und Autoren: Papineau D, De Gregorio BT, Sagar J, Thorogate R, Wang J, Nittler L, Kilcoyne DA, Marbach H, Drost M, Thornton G
Zeitschrift: Journal of the Geological Society
Jahr der Veröffentlichung: 2019
Band: 176
Heftnummer: 4
Seitenbereich: 651-668
ISSN: 0016-7649


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 c. 1850 Ma Michigamme silicate banded iron formation from Michigan, metamorphosed above 550°C. 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 3.6 Å, forms microscopic concentrically-layered and radiating polygonal flakes and has homogeneous δ13C 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 clayrich 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.


FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Drost, Martin
Lehrstuhl für Physikalische Chemie II
Marbach, Hubertus PD Dr.
Lehrstuhl für Physikalische Chemie II


Einrichtungen weiterer Autorinnen und Autoren

Carnegie Institution for Science
Lawrence Berkeley National Laboratory (LBNL)
University College London (UCL)
U.S. Naval Research Laboratory


Zitierweisen

APA:
Papineau, D., De Gregorio, B.T., Sagar, J., Thorogate, R., Wang, J., Nittler, L.,... Thornton, G. (2019). Fossil biomass preserved as graphitic carbon in a late paleoproterozoic banded iron formation metamorphosed at more than 550°C. Journal of the Geological Society, 176(4), 651-668. https://dx.doi.org/10.1144/jgs2018-097

MLA:
Papineau, Dominic, et al. "Fossil biomass preserved as graphitic carbon in a late paleoproterozoic banded iron formation metamorphosed at more than 550°C." Journal of the Geological Society 176.4 (2019): 651-668.

BibTeX: 

Zuletzt aktualisiert 2019-17-07 um 08:38