Document Type

Conference Proceeding

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Publication Title

Guidebook for Field Trips in the Connecticut Valley Region of Massachusetts and Adjacent States


The eastern limb of the Berkshire anticlinorium of western Massachusetts (Figure 1) is a complex, multiplydeformed, polymetamorphic, Taconian/Acadian orogenic terrane. The geologic framework of this area is well established, originally by the mapping of B.K. Emerson (1892, 1898, 1899) and Pumpelly et al. (1894), as summarized on the Massachusetts geologic map of Emerson (1917), and more recently by the mapping of L.M. Hall, N.L. Hatch, S.A. Norton, P.H. Osberg, N.M. Ratcliffe, and R.S. Stanley, as summarized on the Massachusetts geologic map of Zen et al. (1983). The summary reports of USGS Professional Paper 1366 in 1988 as well as the work of Hatch et al. (1984), Stanley and Ratcliffe (1985), and Sutter et al. (1985), among others, provide a provocative regional synthesis that brings into sharp focus a variety of interrelated structural, stratigraphic, petrologic, and geochronologic problems.

Despite vigorous efforts, our ability to constrain the timing of many fundamental events is still hampered by both the complexity of the terrane and a lack of data. As reviewed by Karabinos and Laird (1988), differentiating between the effects of different metamorphic events remains quite problematic in much of the terrane. The recent work of Hames et al. (1991) and Armstrong et al. (1992) emphasizes the problem of differentiating between Taconian and Acadian orogenic effects along the zone of maximum overlap, which generally coincides with the axis of the Berkshire massif. This field trip (see figure 10 for route) will review the nature of this polymetamorphism in a nearly continuous belt of high-alumina, Gassetts-like schists of the Hoosac formation that occurs along the eastern margin of the Berkshire massif. As a bonus we will have the opportunity to examine the nearly continuous prograde metamorphic evolution of a relatively unusual, but mineralogically interesting, bulk composition that has historically received much attention.



First Page



From the 84th Annual Meeting New England Intercollegiate Geological Conference (NEIGC), The Five Colleges, Amherst, Massachusetts, October 9-10-11, 1992.

Published in the UMass Department of Geosciences, Geoscience Contribution Series found online.

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