A Review of Proterozoic to Early Paleozoic Lithotectonic Terranes in New Brunswick, Canada and their Tectonic Evolution during Penobscot, Taconic, Salinic and Acadian Orogenesis

Abstract

Geological relationships preserved in the New Brunswick segment of the Appalachian orogen are key to deciphering the complex tectonic events that occurred during the closing of the Paleozoic Iapetus Ocean. These events can be explained in terms of geodynamic interactions between eight lithotectonic terranes. The first, the Caledonia terrane, comprises Neoproterozoic volcanic arc sequences and comagmatic plutons considered to form part of the microcontinent of Avalonia. The seven other terranes are associated with the microcontinent of Ganderia and consist of (1) Brookville terrane-Mesoproterozoic to Neoproterozoic platformal carbonates and Neoproterozoic to Early Cambrian plutonic rocks, (2) New River terrane-Neoproterozoic volcanic arc sequences and comagmatic plutons overlain by a Cambrian Penobscot volcanic arc sequence, In New Brunswick, closure of the Iapetus Ocean is attributed to four major tectonic episodes: (1) the Penobscot orogeny, which accreted the Miramichi, Annidale, and St. Croix terranes to the New River terrane on the trailing edge of Ganderia by closing a Penobscot backarc basin in the Early Ordovician, (2) the Taconic orogeny, which accreted the Popelogan terrane on the leading edge of Ganderia to the Laurentian margin in the Late Ordovician and effectively closed the main tract of the Iapetus Ocean, (3) the Salinic orogeny, which accreted the Elmtree and Miramichi terranes to the Laurentian margin by closing the Tetagouche backarc basin in the Silurian, and (4) the Acadian orogeny, which accreted the Caledonia terrane (Avalonia) to the Brookville and New River terranes on the trailing edge of Ganderia in the latest Silurian to earliest Devonian and in the process closed the last remaining oceanic tract in the northeastern Appalachians. RÉSUMÉLes corrélations géologiques préservées dans la partie du Nouveau-Brunswick de l'orogène des Appalaches sont essentielles pour bien comprendre le déroulement des événements tectoniques complexes survenus au moment de la fermeture de l'océan Iapetus, pendant le Paléozoïque. Il est possible d'expliquer ces événements par des interactions géodynamiques entre huit terranes lithotectoniques. Le premier, soit le terrane calédonien, comprend des séquences d'arc volcanique et des plutons comagmatiques du Néoprotérozoïque dont on estime qu'ils faisaient partie du microcontinent Avalonia. Les sept autres terranes sont associés au microcontinent Ganderia et comprenaient les terranes que voici : (1)

The Grand Manan Terrane of New Brunswick: Tectonostratigraphy and Relationship to the Gondwanan Margin of the Iapetus Ocean

“…1, 2). These terranes record the episodic expansion and contraction of the Iapetus Ocean that led to the transfer of Ganderia from the Gondwanan to the Laurentian margin (van Staal et al , 2012Fyffe et al 2011a;Johnson et al 2012).…”

“…1, 2), namely the Caledonia, Brookville, and New River terranes (see Fyffe et al 2011a, and references therein). The Brookville and New River terranes are considered to represent remnants of the Gondwanan continental margin fringing the Paleozoic Iapetus Ocean.…”

“…U-Pb analyses of zircon from a felsic volcanic breccia near the top of the Mosquito Lake Road Formation yielded an age of 514 ± 2 Ma based on two zircon fractions (Johnson and McLeod 1996;Johnson 2001;McLeod et al 2003;Fyffe et al 2009). The Ellsworth volcanic rocks are interpreted to represent a small ocean rift or a remnant arc that was located along the southeastern margin of the Iapetus Ocean (Schultz et al 2008;Fyffe et al 2011a;Johnson et al 2012).…”

“…1), each with a distinctive stratigraphic and structural history that can be related to its paleogeographic position within the Iapetus Ocean during the Early Paleozoic (Fyffe et al 2011a). However, the relationship of the pre-Triassic rocks of Grand Manan Island, located in the Bay of Fundy off the southwestern coast of New Brunswick, to the terranes on the Figure 1.…”

U-Pb (zircon) age for the Beaver Harbour Porphyry, New River belt, southern New Brunswick, Canada

“…1) with contrasts in ages and rock types (e.g., Barr et al 2014). Caledonia, the belt located most outboard from the Laurentian margin, is generally considered to be part of Avalonia, whereas the other belts have been interpreted to be part of Ganderia, although the original relationships among the belts are not entirely clear (e.g., Barr et al 2014;Hibbard et al 2006;Fyffe et al 2009Fyffe et al , 2011. The focus of the present study is in the New River belt, which is dominated by volcanic and plutonic rocks which have yielded diverse U-Pb (zircon) ages of ca.…”