Detailed mapping of an area near Middlebury, Vermont, reveals a multiple deformational scheme quite different from that previously proposed. The published stratigraphy of the middle Ordovician limestones, on which earlier structural theories are based; was found to be inaccurate, so a new system has been defined. An unreported early generation of cleavage has been discovered which indicates the existence of a decollement zone in the upper Bascom formation. The second generation of cleavage and its associated folding were well defined by earlier workers, but this study shows that it is also a thin-skinned event.
The last deformation, as exhibited by crenulation cleavage development, was restricted to narrow zones. These zones are shown to be related to thrusting. The thrusts are probably rooted in the decollement in the upper Bascom formation. Thus the deformation is found to be totally thin-skinned, which is contrary to the prior theory of the Middlebury synclinorium.
Washington, P.A., 1981. Structural Analysis of an Area near
Middlebury, Vermont. Unpublished MSc. thesis, State
University of New York at Albany.
121 pp., +vii; 2 folded plates (maps)
University at Albany Science Library call number: SCIENCE Oversize (*) QE 171 W26X
thesis (scanned text) - 8.4MB pdf file
1 - Bedrock Geology near Middlebury, Vermont
(coloured outcrop map, scale 1: 6,000) - 11MB pdf file
Plate 2 - Geologic Cross-sections for an area near Middlebury, Vermont
(coloured geological cross-sections, scale 1: 6,000) - 3.2MB pdf file
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