Evidence for tectonic emplacement of ultramafic and associated rocks in the pre-Silurian eugeoclinal belt of western New England; vestiges of an ancient accretionary wedge

Abstract

In northern Vermont, detailed 1:10,000 mapping of the Hazens Notch, Ottauquechee, Stowe, and Moretown formations in the 60 km ² Jay area has shown that metasedimentary rocks and serpentinites are highly faulted to produce a tectonic stratigraphy in which serpentinites and talc-carbonate rocks occur as slivers along faults that separate contrasting lithic assemblages. Remnants of the ophiolite sequences of Quebec. In western Massachusetts, the ultramafic-bearing section of the Rowe Schist and the western part of the Moretown Formation are largely equivalent to the rocks in northern Vermont. Mapping at 1:24,000 scale and compilation work for the new bedrock map of Massachusetts have shown that the Rowe Schist consists of numerous lenses of greenschist, carbonaceous schist, gray schist, amphibolite, and serpentinite. Although the geometric arrangement of the lenses and serpentinites is strikingly similar to that seen in the Jay area, higher grade Taconian and Acadian metamorphism has partially obscured the fault fabrics seen in Vermont.--Modified journal abstract.