Skip to main content
U.S. flag

An official website of the United States government

The origin of epigenetic graphite: Evidence from isotopes

January 1, 1981

Stable carbon isotope ratios measured in syngenetic graphite, epigenetic graphite, and graphitic marble suggests that syngenetic graphite forms only by the metamorphism of carbonaceous detritus. Metamorphism of calcareous rocks with carbonaceous detritus is accompanied by an exchange of carbon between the two, which may result in large changes in isotopic composition of the non-carbonate phase but does not affect the relative proportions of the two reactants in the rock. Epigenetic graphite forms only from carbonaceous material or preexisting graphite. The reactions involved are the water gas reaction (C + H2O → CO + H2) at 800–900°C, and the Boudouard reaction (2CO → C + CO2), which probably takes place at temperatures about 50–100°C lower.

Publication Year 1981
Title The origin of epigenetic graphite: Evidence from isotopes
DOI 10.1016/0016-7037(81)90086-7
Authors P. L. Weis, I. Friedman, J.P. Gleason
Publication Type Article
Publication Subtype Journal Article
Series Title Geochimica et Cosmochimica Acta
Index ID 70011719
Record Source USGS Publications Warehouse