Title: Petrography and petrology of the Middlefield Granite
Abstract:The Middlefield Granite is a small elliptical body, roughly three miles long and one and a half miles wide, enclosed in a series of eugeosynclinal metasediments and located in the Chester quadrangle i...The Middlefield Granite is a small elliptical body, roughly three miles long and one and a half miles wide, enclosed in a series of eugeosynclinal metasediments and located in the Chester quadrangle in west central Massachusetts The purpose of the study was to map and describe the Middlefield Granite and to determine through field and petrographic studies as much as possible about the history, origin, mode of formation of the rock, and its relation (time and space) to the surrounding country rocks.A geologic map of the granite and surrounding rocks, based on the author's field investigations, is presented.As a result of the petrographic examination of granite thin sections, the minerals present are described, with estimated modes tabulated: plagioclase, averaging An12 , (38.7%); perthitic microcline (24.0%); quartz (24.1%); biotite (6.0%); muscovite (4.0%); epidote (2.5%); and other accessories (0.8%).Read More