Origin of epigenetic calcite in coal from Antarctica and Ohio based on isotope compositions of oxygen,carbon and strontium

Isotopic compositions of oxygen, carbon and strontium of calcite cleats in coal seams of southern Victoria Land, Antarctica, and Tuscarawas County, Ohio, contain a record of the conditions a the time of their formation. The Antarctic calcites (δ ¹⁸O(SMOW) = +9.14 to +11.82%₀) were deposited from waters enriched in ¹⁶O whose isotopic composition was consistent with that of meteoric precipitation at low temperature and high latitude. The carbon of the calcite cleats (δ ¹³C(PDB) = ?15.6 to ?16.9%₀) was derived in part from the coal (δ ¹³C(PDB) = ?23.5 to ?26.7%₀) as carbon dioxide and by oxidation of methane or other hydrocarbon gases. The strontium (${}^{87}\text{Sr}{}^{86}\text{Sr}\text{= 0.71318–0.72392)}$ originated primarily from altered feldspar grains in the sandstones of the Beacon Supergroup.Calcite cleats in the Kittaning No. 6 coal seam of Ohio (δ ¹⁸O(SMOW) = +26.04 to +27.79%₀) were deposited from waters that had previously exchanged oxygen, possibly with marine carbonate at depth. The carbon (δ ¹³C(PDB) = 0.9 to +2.4%₀) is enriched in ¹³C even though that cleats were deposited in coal that is highly enriched in ¹²C and apparently originated from marine carbonates. Strontium in the cleats ($\text{Sr}\text{87}$ 0.71182–0.71260) is not of marine origin but contains varying amounts of radiogenic ⁸⁷Sr presumably derived from detrital Rb-bearing minerals in the adjacent sedimentary rocks. The results of this study suggest that calcite cleats in coal of southern Victoria Land, Antarctica, were deposited after the start of glaciation in Cenozoic time and that those in Ohio precipitated from formation waters derived from the underlying marine carbonate rocks, probably in the recent geologic past.