See more from this Division: Topical Sessions
See more from this Session: Recent Advances in the Understanding of Adirondack and Southern Grenville Province Tectonics I: In Honor of James McLelland
Abstract:
In contrast, the Franklin Marble and other scattered marbles in the New Jersey Highlands have a more narrow range in carbon isotopes (0.3±0.7) than most other Grenville terranes, consistent with an origin as a single depositional unit. Although local occurrences of stromatolites, tourmaline, and serendibite are suggestive of shallow water and evaporitic environments, stable isotopes are not as distinct as those at Kilmar or the Balmat deposit in the Adirondacks. Marble-hosted Zn-Fe-Mn ore deposits at Franklin and Sterling Hill likely formed from alteration of the Franklin Marble by water rich-fluids, and so preserve protolith carbon isotopes while showing a range in oxygen isotopes (11.7-17.6; Johnson et al. 1990). Genetically related marble-hosted magnetite deposits have similar oxygen isotope ratios, but with δ13C values that range from 0.7 to -5.0. We interpret ore deposits in the Franklin Marble to have formed from hydrothermal fluids in a back arc basin at ca. 1.3 Ga. Subsequent granulite-facies metamorphism of ore deposits and marble during the Ottawan orogeny is recorded by calcite-graphite carbon isotope fractionations corresponding to temperatures of 767±41°C.
See more from this Division: Topical Sessions
See more from this Session: Recent Advances in the Understanding of Adirondack and Southern Grenville Province Tectonics I: In Honor of James McLelland