Stratigraphy and tectono-sedimentary evolution of the Late Ordovician to Middle Devonian Gaspé Belt in northern New Brunswick: evidence from the Restigouche area

Abstract

The Gaspé Belt in the Restigouche area comprises three successions separated by a Late Silurian (Salinic) disconformity and an Early Devonian angular unconformity. The lower, Upper Ordovician to Lower Silurian sequence consists of siliciclastic turbidites of the Boland Brook and Whites Brook formations (Grog Brook Group), overlain by calcareous turbidites of the Pabos and White Head formations (Matapédia Group), and slope and shelf deposits of the Upsalquitch and Limestone Point formations (lower Chaleurs Group). Above the Salinic disconformity, the upper Chaleurs Group and the Dalhousie Group record a transgressive–regressive cycle. The former comprises Pridolian carbonate rocks of the West Point Formation and overlying Pridolian to Lochkovian sedimentary rocks of the Indian Point Formation. The Chaleurs Group is conformably overlain by Lochkovian to early Emsian subaerial volcanic rocks of the Dalhousie Group (Val d'Amour Formation), which is unconformably overlain by alluvial–lacustrine deposits of the late Emsian Campbellton Formation. Acadian orogenesis began during the Emsian and is characterized by open to closed folding, heterogenous cleavage development, and reverse and strike-slip faults. The Salinic orogeny is manifested in extensional block faulting, within-plate volcanism, and uplift and deep erosion of Early Silurian strata. Early Devonian high-level intrusion of the Matapédia Group, White Head clasts in Indian Point conglomerate, and thermal maturation data all indicate an extended period of Late Silurian – Early Devonian uplift in parts of the Restigouche area. Thermal maturities of West Point and Indian Point strata are within the oil and condensate windows and suggest potential for hydrocarbons in the study area.

The camerate crinoid Scyphocrinites Zenker in the Upper Silurian or Lower Devonian of New Brunswick, Canada

“…Spores and acritarchs (Wilson et al 2004), as well as brachiopods from the Indian Point Formation in Gaspé, Quebec (Bourque and Lachambre 1980), indicate a Pridolian to middle Lockhovian age. Wilson et al (2004) reported a U-Pb (zircon) age of 415.0 ± 0.5 Ma for the Squaw Cap Felsite, which intrudes the Indian Point Formation. Terminology used for the crinoid endoskeleton follows Moore et al (1978) and Ubaghs (1978a).…”

“…The Indian Point Formation consists mainly of moderately to strongly calcareous mudstone, fine-grained sandstone and wackestone, and commonly contains fossils of stromatoporoids, brachiopods, trilobites, crinoids and rugose corals (Wilson et al 2004). Spores and acritarchs (Wilson et al 2004), as well as brachiopods from the Indian Point Formation in Gaspé, Quebec (Bourque and Lachambre 1980), indicate a Pridolian to middle Lockhovian age.…”

“…Although the rarity of cross-laminated or ripplelaminated beds indicates deposition below fair-weather wave base, Wilson et al (2004) Lee (2005), in light of the pivotal research of Haude (1992), loboliths of Scyphocrinites fall into two morphological groups of broadly similar gross morphology. The primitive condition is represented by the so-called cirrus (more correctly these are inflexible radices, not flexible cirri; Donovan 1993) loboliths, formed from amalgamated branching "roots"; this group includes the .…”

“…A shallow nearshore marine setting was postulated by Wilson et al (2004) based on the presence of terrestrial microfossils mixed into a marine environment dominated by brachiopods, crinoids, corals, stromatoporoids and trilobites. Although the rarity of cross-laminated or ripplelaminated beds indicates deposition below fair-weather wave base, Wilson et al (2004) Lee (2005), in light of the pivotal research of Haude (1992), loboliths of Scyphocrinites fall into two morphological groups of broadly similar gross morphology.…”

A eurypterid from the lacustrine facies of the Early Devonian Campbellton Formation, New Brunswick, Canada

“…The Campbellton Formation overlies the Val d' Amour Formation rhyolite dated at 407.4 ± 0.8 Ma (Wilson et al 2004). Miospores in the Campbellton Formation place it in the Emphanisporites annulatus-Camarozonotriletes sextantii Assemblage Zone which corresponds approximately to the Polygnathus dehiscens to Polygnathus serotinus conodont zones of early Emsian to early late Emsian age (Richardson and McGregor 1986).…”