Blocky calcite cement from the Suwannee Terrane: Evidence for mixing of middle to high latitude meteoric and sea water

Abstract

Blocky calcite cement from the Suwannee Terrane, an exotic terrane juxtaposed against Gondwanaland during the Ordovician and now located in Georgia, Florida, and Alabama, has δ13C = −7.8 to −16.5‰ PDB and δ18O = −6.8 to −11.6‰ PDB. This cement is interpreted to have formed during sulfate reduction, which is supported by the coeval presence of pyrite and non-ferroan calcite cement. Isotopic values define part of a mixing line between calcite cements precipitated from marine, organic carbon-dominated and meteoric, inorganic-carbon dominated fluids.