Exploring the Root Zone of an Ancient Fault-driven Hydrothermal System in the Adirondack Lowlands, New York

This trip examines exposures in the Adirondack Lowlands that contain Paleozoic hydrothermal and faultrelated features hosted by Mesoproterozoic ‘Grenville’ marbles and Cambrian Potsdam Sandstone. These features have been the source of some debate historically and are now explicable as resulting from hydrothermal activity within an ancient wrench fault system. This system is similar to the deep structures that give rise to economically important gas and oil fields in the Appalachian Basin and elsewhere. The trip will include localities where the direct effects of coupled fault-related deformation and hydrothermal alteration can be seen, and the results of recent petrographic, stable isotope and fluid inclusion work will be used to better explain outcrop-scale features. The trip concludes with a stop in Ordovician Black River Group carbonates that demonstrates on a small scale the effects of hydrothermal dolomitization related to brittle deformation that may be linked to basement faulting. The regional extent, timing and tectonic significance of the fault systems will also be considered. Figure 1. Generalized geolo Gouverneur