Petrogenesis of arsenic and platinum-group minerals from a partially serpentinized dunite in East Dover, Vermont, USA

In the Appalachian Mountains of Vermont, USA, variably serpentinized ultramafic rocks mark Ordovician Taconic orogenic suture zone. These provide evidence for several alteration events that occurred during orogenesis. The largest these bodies occurs as a partially meta-dunite located in East Dover, Vermont. Whole-rock X-ray fluorescence spectroscopy and electron microprobe data on samples are interpreted with respect to processes including fluid/melt-rock interaction mantle, serpentinization, subsequent regional metamorphism. We report first discovery nickel arsenide minerals hosted this meta-dunite, well rare occurrences platinum-group mineral inclusions chromitite. Although chromitite rare, their occurrence chemistry suggest they formed by partial melting produced dunite, likely supra-subduction zone setting. Arsenic un-serpentinized but ubiquitous highly samples, which suggests most arsenic was introduced into serpentinization. geochemical analyses also indicate contain highest concentrations arsenic. identifies potential source explain elevated groundwater is serious health concern places where wells have been drilled serpentinite bedrock.