Stratigraphic Relationships and Detrital Composition of the Medial Ordovician Flysch of Western New England: Implications for the Tectonic Evolution of the Taconic Orogeny

Abstract

We present new stratigraphic and petrographic data on the easterly-derived medial Ordovician flysch sequence of western New England and eastern New York State. A conformable relationship exists between the flysch and underlying early Paleozoic continental rise sediments within the western Taconic Allochthon. Farther east in the Allochthon we observe a possibly disconformable relationship. Contrary to previous interpretations, these facts suggest that at any place within this paleogeographic realm the sediments were undeformed and untransported at the initiation of flysch deposition. At least three sources contributed detritus to the flysch: (1) Taconic Sequence sediments; (2) deformed and metamorphosed pelitic, psammitic, and volcanic lithologies; and (3) igneous rocks of dominantly mafic-ultramafic affinities. These three sources are respectively interpretable as: continental rise, accretionary prism, and ophiolitic-volcanic arc assemblages, which are recognized in the regional geology of western New Eng...