Granitoid rocks and terrane characterization: An example from the northern Appalachian Orogen

Abstract

Granitoid rocks in the Aspy, Bras d'Or, and Mira terranes of Cape Breton Island in the northern Appalachian Orogen display contrasts in age and petrological characteristics that reflect differences in source rocks and tectonic events in these three terranes. The Aspy Terraiie is characterized by a protracted Silurian and Devonian plutonic history, during which granitoid rocks were generated sequentially in volcanic-arc, post-arc, collisional, and extensional tectonic settings. In contrast, the Bras d'Or and Mira terraiies are characterized by Late Precambrian calc-alkalic I-type granitoid suites, and only minor Devonian plutonism. Late Precambrian suites in the Bras d'Or Terrane (age ca 565-555 Ma) are significantly younger than those in the Mira Terrane (age cn. 620 Ma), and the two suites are interpreted to have formed in separate volcanic arcs.

The La Coulée Formation, a new post-Acadian continental clastic unit bearing groundwater calcretes, Gaspé Peninsula, Quebec

“…Many other similar highlands occupied by Devonian to Permian plutonic complexes are found throughout the Maritime provinces (Fyffe et al 1981;Barr 1990;Fyffe and Barr 1986;Waldron el al. 1989;Pe-Piper 1991;Pe-Piper et al 1991;McDonald et al 1992;Piper et al 1993;Kontak 1994).…”

Regional 18O-depletion of Neoproterozoic igneous rocks from Avalonia, Cape Breton Island and southern New Brunswick, Canada

“…This terrane is dominated by Silurian-Devonian volcanic and plutonic rocks that can be divided into four main groups: (1) ca. 440-430 Ma igneous suites formed in a backarc basin (Barr, 1990;Barr and Jamieson, 1991;Barr et al, 1998); (2) ca. 400 Ma monzogranitic plutonic suites generated in a volcanic-arc environment (Barr, 1990;Lin et al, 2007); (3) ca.…”

“…440-430 Ma igneous suites formed in a backarc basin (Barr, 1990;Barr and Jamieson, 1991;Barr et al, 1998); (2) ca. 400 Ma monzogranitic plutonic suites generated in a volcanic-arc environment (Barr, 1990;Lin et al, 2007); (3) ca. 375 Ma plutonic suites generated during the ongoing collision of the Bras d'Or and Aspy terranes (Barr, 1990); and (4) ca.…”

“…400 Ma monzogranitic plutonic suites generated in a volcanic-arc environment (Barr, 1990;Lin et al, 2007); (3) ca. 375 Ma plutonic suites generated during the ongoing collision of the Bras d'Or and Aspy terranes (Barr, 1990); and (4) ca. 365 Ma volcanic and sedimentary rocks and associated syenogranitic plutonic suites generated in a late orogenic to within-plate, extensional tectonic regime (Barr, 1990).…”

“…1 and 2A). Similarly, Fyffe and Fricker (1987) and Barr andWhite (1989, 1996) divided southern New Brunswick into six distinct terranes: St Croix, Mascarene, New River, Kingston,Brookville,and Caledonia (Figs. 1 and 2B).…”