Variations in deformation styles within the central Maine terrane: An example from the Presidential Range, NH
- Bates College, Lewiston, ME (United States). Dept. of Geology
The Silurian and Devonian cover rocks of the Central Maine Terrane in the northern Appalachians are a complex, highly metamorphosed, stratigraphy that has been equally, if not more complexly, deformed. Correlations of regional deformation sequences (be they Acadian and/or Alleghanian) have been difficult, controversial, and elusive. This stems from the common observation that across-strike and strike-parallel variations in deformation sequences appear to be the norm rather than the exception in this belt. Enormous variations in structural style have been routinely observed in a detailed, five-year study of the well-exposed outcrops above treeline in the Presidential Range. Domains of different structural styles have been mapped in the northern, central and southern portions of the range. The northern domain, including Mts. Madison, Adams, and Jefferson, is composed of various members of the Devonian Littleton Formation. The map pattern is dominated by three macroscopic F1 synclines that face and are interpreted to verge northeasterly. The central domain, which includes Mt. Clay and much of Great Gulf, is interpreted to be a klippe of presumably Silurian gneisses probably correlative to the Rangeley, Smalls Falls, and Madrid Formations. A stratigraphic discontinuity, interpreted as the Greenough Spring thrust fault, separates this domain from the others and truncates the early fold structures of all domains. Within the Klippe there is evidence for an early phase of deformation but no folds related to it have been mapped. The map pattern is dominated by second phase folds that deform the early schistosity. The Greenough Spring thrust fault, and the second phase folds within it are refolded by a late phase of deformation which is characterized by a macroscopic, overturned synform.
- OSTI ID:
- 5933777
- Report Number(s):
- CONF-9303211-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:2; Conference: 28. annual Geological Society of America (GSA) Northeastern Section meeting, Burlington, VT (United States), 22-24 Mar 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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