A new U-Pb (zircon) age of 357 ±1 Ma for the Wedgeport pluton in the Meguma terrane of southwestern Nova Scotia confi rms that it is younger than other granitoid plutons of the Meguma terrane but not as young as the ca. 316 Ma age based on previous geochronological work. The pluton consists of mainly homogeneous biotite monzogranite characterized by abundant accessory phases including garnet, zircon, epidote, titanite, and ilmenite. Major minerals are quartz, plagioclase (albite-oligoclase), and perthitic microcline. The pluton has consistently high SiO 2 content (average ca. 75%) but shows some internal variation consistent with fractional crystallization of feldspar and biotite, together with accessory phases such as zircon. Tectonic setting during emplacement of the pluton was likely within plate, but classifi cation is ambiguous because the pluton has characteristics of all three granite types. Peraluminous composition and presence of ilmenite and aluminous minerals such as Fe-rich biotite and garnet suggest S-type affi nity, but other characteristics such as high-level emplacement, accessory fl uorite, and some chemical characteristics (high Ga/Al ratio, elevated Nb and Y) indicate A-type affi nity, whereas abundant titanite and overall chemical character is compatible with felsic I-type composition. The granite has specialized characteristics such as elevated Rb relative to Sr and Ba, and high U and Th compared to all of the average granite types. High ε Nd values (+2 to+3) indicate a relatively primitive source compared to other plutons of the Meguma terrane. The Wedgeport pluton appears to be unique in the Meguma terrane in both age and composition, although similar plutons may occur in inboard terranes of the Appalachian orogen. RÉSUMÉUne nouvelle datation au U-Pb (à partir de zircon) situant à environ 357 Ma le pluton de Wedgeport à l'intérieur du terrane de Meguma dans le Sud-Ouest de la Nouvelle-Écosse, confi rme qu'il est plus récent que les autres plutons granitiques du terrane de Meguma, mais qu'il a plus des 316 Ma qu'on lui avait attribués dans le cadre de travaux géochronologiques antérieurs. Le pluton est constitué de monzogranite à biotite principalement homogène caractérisé par des phases accessoires abondantes, notamment du grenat, du zircon, de l'épidote, de la titanite et de l'ilménite. Les principaux minéraux présents sont le quartz, le feldspath plagioclase (albite-oligoclase) et la microcline perthitique. Le pluton a une teneur constamment élevée en SiO 2 (en moyenne environ 75 %), mais il présente une certaine variation interne correspondant à une cristallisation fractionnée des feldspaths et de la biotite, ainsi que des phases accessoires, dont du zircon. L'intrusion du pluton est probablement survenue dans un cadre tectonique intra-plaque, mais sa classifi cation est ambiguë parce que le pluton possède des caractéristiques des trois types de granites. Sa composition hyperalumineuse et la présence d'ilménite et de minéraux alumineux, comme de la biotite riche en fer et du grenat, lais...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.