U–Pb Age of the Stanley Brook Granite, Grand Manan Island, New Brunswick

• Published in: Atlantic Geology
• Main Authors: Fyffe, Leslie R., van Staal, Cees R., Valverde-Vaquero, Pablo, McNicoll, Vicki J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Atlantic Geoscience Society 2011
• Subjects: Geochronology; Granite; Grand Manan; New Brunswicki; Manan; Priest Cove; Ross Island
• Online Access: https://journals.lib.unb.ca/index.php/ag/article/view/atlgeol.2011.001

The Stanley Brook Granite on Grand Manan Island has yielded an Early Cambrian U-Pb zircon age of 535 ± 2 Ma. The granite was emplaced into sedimentary rocks of the Flagg Cove Formation of the Castalia Group, proving that the latter is no younger than Early Cambrian. Previous dating of detrital zircons from the Flagg Cove Formation limits its maximum depositional age to be no older than 574 ± 7 Ma. The intrusive age of the Stanley Brook Granite is essentially identical to the 539 ± 3 Ma age obtained previously from dacitic tuff of the Priest Cove Formation, suggesting a comagmatic relationship between the two. The contact between the Flagg Cove and Priest Cove formations is invariably faulted. However, the consanguineous relationship between the Priest Cove Formation and Stanley Brook Granite suggests that the Priest Cove Formation was deposited on the Flagg Cove Formation. This proposed stratigraphic relationship supports the interpretation that the tuffaceous and volcaniclastic sedimentary rocks of the Priest Cove Formation represent a distal facies of the mafic flows and fragmental volcanic rocks of the Ross Island Formation. The age of the Stanley Brook Granite is consistent with the interpretation that Mesoproterozoic (?) to Neoproterozoic platformal carbonate rocks of the Brookville terrane represent basement to Neoproterozoic volcanic rocks of the New River terrane. RÉSUMÉ L’âge U-Pb sur zircon du granite du ruisseau Stanley, sur l’île Grand Manan, se situerait à environ 535 ± 2 Ma et remonterait au début du Cambrien. Ce granite a été mis en place dans les roches sédimentaires de la Formation de Flagg Cove du groupe de Castalia, ce qui établirait que cette dernière formation date tout au plus du début du Cam-brien. Les travaux de datation précédents des zircons détritiques de la Formation de Flagg Cove ont fixé l’âge maximal de la sédimentation à 574 ± 7 Ma, tout au plus. Pour l’essentiel, l’âge de l’intrusion du granite du ruisseau Stanley correspond à l’âge de 539 ± 3 Ma déjà déterminé pour le tuf ...