Post-metamorphic low δ13 C calcite in the Cycladic complex (Greece) and their implications for modeling fluid infiltration processes using carbon isotope compositions
Ganor, Jiwchar; Matthews, Alan; Schliestedt, Manfred
European Journal of Mineralogy Volume 6 Number 3 (1994), p. 365 - 380
published: Jun 7, 1994
manuscript accepted: Feb 21, 1994
manuscript received: Aug 23, 1993
ArtNo. ESP147050603003, Price: 29.00 €
Abstract Calcite veins and overgrowths with δ13C values of -12 ‰ to -8 ‰ and δ18O values of 24 ‰ to 27 ‰ are shown to be characteristic features of the Cyclades metamorphic complex of Greece. Field and petrographic characteristics and the marked carbon and oxygen isotope disequilibrium that the veins and overgrowths show with host metamorphic rocks indicate that they developed during post-metamorphic evolution of the complex. The low δ C values are interpreted to be either the result of the oxidation of organic carbon or solution of soil CO2 by surface waters moving downwards along extensional fractures generated during the late stages of exhumation. Carbon and oxygen isotopic compositions reported for the carbonate fraction of many pelitic schists on Naxos overlap with the range of these late carbonates and may in part reflect a contribution of this late calcite. Uncertainties regarding the origin of low δ13 C values in the carbonates of metamorphic rocks shows that they must be used with caution as tracers of fluid-rock exchange.