MINERALOGICAL AND ISOTOPIC STUDY OF A CALCITE VEIN NEAR EDWARDS, NEW YORK

This study is one of two research projects focusing on different aspects of a ≤5 m-wide, pink and gray-colored calcite vein that cross-cuts metamorphosed host rock near Edwards, New York.

The goals of this study are to determine: 1) the compositional difference between the pink and gray calcite, 2) the temperature of vein formation and its source fluid composition, and 3) the complete mineral assemblage that comprises the vein.

The vein consists mostly of calcite with pyroxene > biotite > sulfides (pyrite, molybdenite) >> barite, celestite, parisite. The calcite is pink in color in the center of the vein and gray along the contact with the wall rock. The calcite, pyroxene, and biotite within the vein all form ≤ 5 cm-long euhedral crystals; the sulfides and other minerals are smaller (≤1 cm-long) and less common. The host rock is comprised of massive, fine-grained pyroxene with rare disseminated molybdenite.

Preliminary and ongoing analysis of primary fluid inclusions within the pink calcite indicate Th = 133.8°C (avg., n=5; temperature minimums; Th values not pressure corrected) and Tm = -8.9°C (salinity = 12.73 eq wt% NaCl). All fluid inclusions homogenize to liquid. Pink calcite O stable isotope data (δ¹⁸O_SMOW = +18.3‰) and fluid inclusion Th data preliminarily suggest a minimum source fluid composition of δ¹⁸O_SMOW= +4.3‰; work to refine this value by determining an appropriate pressure correction is ongoing.

Data for all other aspects of this study are forthcoming.