The geology of the Farmington quadrangle, Maine
Furlong, Ira E
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The Farmington Quadrangle is located in west central Maine within the New England Physiographic Province. Meta-sedimentary rocks of the Mid-Paleozoic age comprise approximately two thirds of this area. The remaining one third reveals phanerocrystalline granite rocks, divided into magmatic and granitized zones. The oldest recognized stratigraphic unit in the Farmington Quadrangle is the Smalls Falls (Parmachenee) Formation. This unit is characterized by dark, maroon stained, thinly bedded, highly sulfidic argillaceous rock with minor intercalated arenaceous and calcareous units. This formation was deposited under anaerobic conditions in closed basins. The Madrid Formation lies above the Smalls Falls Formation and is characterized by intercalated calcerous arenaceous units with some argillaceous and calcareous horizons. Near the top of the Madrid Formation lies the Dyer Hill Member which is a dark argillaceous rock. The stratigraphic units have been subjected to regional metamorphism. The metamorphism increases from low grade, chlorite intensities in the northern sector of the quadrangle to high grade, sillimanite intensities in the southern region of the quadrangle. Contact thermal metamorphic effects are superimposed on the regional metamorphism in the Clearwater Pluton area. The phanerocrystalline rock bodies are ascribed to extensive transformations of sediments in localized deeper areas of the geosyncline which produced magmatic core areas bordered by granitized and metamorphic zones. Some of the granitic magmatic material has been intruded into the overlying rocks while some has remained essentially in situ. The attitude of the rocks in the quadrangle reflect intense structural deformation. The regional strike of the bes is N.N.E and dips are usually very steep to the N.W. Shear zones both transverse and longitudinal are ubiquitous; there are many drag folds of diverse orientation associated with the shear zones. Pleated folding is suggested as the explanation for the regional structure. Isoclinal folding is held untenable due to the absence of: converging strikes of bes; lack of crests and troughs; and readily identifiable repetition of beds. The late mature topography reflects pre-glacial conditions which were modified by Pleistocene glacial erosion and deposition. The method used to map the less accessable areas of the Farmington Quadrangle was th pace and compass method. Extensive field notes were recorded and evaluated. One hundred and sixty three thin sections were prepared and studied. A geological map and the geological history of the Farmington Quadrangle was developed from these data.
Thesis (Ph.D.)--Boston University
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