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

摘要

The Gaspe 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 (Matapedia 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 Matapedia 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.