Abstract
Geochemical analysis and field relations of linear dolomite bodies occurring in outcrop in the Mohawk Valley of New York suggest that they have undergone significant fault-related hydrothermal alteration. The dolomite occurs in the Lower Ordovician Tribes Hill Formation, which is regionally an early Ordovician shaley limestone with patchy dolomitization. The outcrop has an en echelon fault, fracture, and fold pattern. A 3D ground penetrating radar survey of the quarry floor has helped to map out faults, fractures, anticlines, synclines and the extent of dolomitization. Most of the dolomitization occurs in fault-bounded synclines or “sags” flanked by anticlines. The dolomite structures are highly localized, occurring around faults and are absent away from the faults and fractures. Trenches cut across the outcrop help relate offset along faults to the overall geometry of the dolomitized bodies. Geochemical analysis, though helpful in characterizing the conditions of dolomitization, does not define its origin absolutely. This study uses fluid inclusions, stable isotopes, 3D-ground penetrating radar, core analysis, and surficial observation which all show a link between faulting, dolomitization, and other hydrothermal alteration. Although the outcrop is much too small and shallow to act as a producing gas field, it serves as a scaled analog for Trenton - Black River hydrothermal dolomite reservoirs of the eastern United States. It may therefore be studied to help petroleum geologists characterize existing gas plays and prospect future areas of exploration.

Slater, Brian E., 2007. Outcrop Analog for Lower Paleozoic Hydrothermal Dolomite Reservoirs, Mohawk Valley, NY
Unpublished MSc. thesis, State University of New York at Albany. 104 pp., +x; folded plate in pocket
University at Albany Science Library call number:  SCIENCE Oversize (*) QE 40 Z899 2007 S??

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