Source contributions to Devonian granite magmatism near the Laurentian border, New Hampshire and Western Maine, USA

Devonian Granite Melt Transfer in Western Maine: Relations Between Deformation, Metamorphism, Melting and Pluton Emplacement at the Migmatite Front

“…All granite samples contain biotite and some contain two igneous micas. One U-Pb zircon age determined by Solar et al (1998;404±2 Ma) is from the central portion of the Lexington pluton, and an identical concordant zircon age from the southern lobe is reported by Tomascak et al (2005;ca. 403 Ma).…”

“…Tomascak et al (2005) report the upper U/Pb intercept age of four zircon fractions is 408±5 Ma (from Solar et al, 1998), and two concordant zircon fractions that suggest an age of ca. 406 Ma is more accurate.…”

“…406 Ma is more accurate. The Sugarloaf pluton (2 specimens; Figure 2; Tomascak et al, 2005) occupies a similar position to the Redington pluton, but is apparently mingled felsic-mafic rocks that bear strong resemblance to large portions of the more mafic part of the adjacent Flagstaff Lake intrusive complex. Rocks are dominantly gabbroic with subordinate felsic rock pods.…”

“…Solar et al (1998) reported crystallization ages for two MIC rocks: a U-Pb zircon age of 389±2 Ma for a granodiorite enclave (referred to as "biotite granite"), and a concordant U-Pb monazite age of 370±1 Ma for a granite ("two-mica leucogranite"). Tomascak et al (2005) reports two samples from distinct parts of the MIC monzodiorite suite yield identical ages, slightly older than the granite (one is at STOP 10, see Figure 2 for location; ca. 377 Ma on four concordant to 3% discordant U-Pb zircon fractions).…”

“…Considering new data, Tomascak et al (2005) grouped the MIC into two principal types of rock: biotite granodiorite to quartz monzodiorite (the monzodiorite suite), and biotite and two-mica granite to granodiorite (granite). Biotite monzodiorite to granodiorite enclaves, petrographically similar to rocks of the monzodiorite suite, occur in the granite.…”