Oxygen, Carbon and Strontium Isotopic Constraints on Fluid Movement During the Acadian Metamorphism in South-Central Maine

Abstract

8t80, 813C and STSr/S6Sr isotopic tracers have been used to constrain the timing, as well as the magnitude and direction of cross-layer fluid flow in Acadian metamorphic rocks in south-central Maine. The area contains pelites, calcareous greywackes and the ~100 m thick Waterville Limestone which were isoclinaUy folded and then intruded by granitoid plutons during the Devonian Acadian orogeny. Metamorphism to andalusite and sillimanite facies and granitic plutonism are thought to be closely associated. Baumgartner and Ferry (1991) and Ferry (in press) use the progress of decarbonation reactions to estimate metamorphic time-integrated fluid fluxes up to ~2.10 4 m3/m 2, with the flow uptemperature and layer parallel (lithological units strike at a high angle to isograds). This study tests predictions of this model by: 1) Determining the timing of fluid-flow from small-scale Rb-Sr isochron systematics. 2) Estimating the magnitude of the cross-layer component. Significant