Irving Friedman D. L. Schmidt 1974 <p>Freshwater deposition of the upper Paleozoic, Gondwana tillite in the Pensacola Mountains is indicated by low &delta; values of +4.9 to +6.1 permil &delta;0 ^{1 8} (SMOW) and -1.8 to -15.9 permil &delta;C^{1 3}(PDB) in primary sedimentary calcite within the tillite. In contrast, Cambrian marine limestone from the Pensacola Mountains contains heavy isotopic abundances that are entirely characteristic of marine deposition.</p> application/pdf en U.S. Geological Survey Continental depositon of Antarctic tillite indicated by carbon and oxygen isotopes article