The Upper Triassic Chedabucto Formation, Guysborough County, Nova Scotia: depositional and tectonic context
DOI:
https://doi.org/10.4138/2027Abstract
The Chedabucto Formation of presumed Late Triassic age crops out at the western end of the Orpheus basin. The formation consists of interbedded conglomerate, sandstone, and mudstone interpreted as the deposits of sand-dominated braided streams, and clast-supported conglomerate interpreted as debris-flow deposits derived from nearby fault talus. The facies and presumed age of the Chedabucto Formation are similar to that of the Wolfville Formation in the Minas subbasin of the Fundy rift basin. These facies may also be present in the lower portion of the Eurydice Formation at the base of the sedimentary section in the offshore Orpheus basin. The location of the outcrops of the Chedabucto Formation suggests that a continuous belt of sedimentation connected the Orpheus and Fundy rift basins in the Late Triassic, forming a "broad terrane" extending from eastern New Brunswick to the Scotian Shelf. The Chedabucto Formation was deposited primarily by an axial river system flowing eastward from the Fundy rift basin to the Orpheus basin. The Minas subbasin of the Fundy rift basin and the Orpheus basin are interpreted as segments of a larger transtensional basin formed by synchronous oblique-sinistral motion on the bounding Cobequid-Chedabucto Fault Basin inversion in the Middle Jurassic probably initiated uplift, resulting in the erosional isolation of the Fundy and Orpheus basins. RÉSUMÉ La Formation de Chedabucto, préumément de I'époque du Trias tardif, affleure à l’extrémité ouest du bassin d'Orphée. La Formation est constituée de mudstones, de grès et de conglomérats interlités interprétés comme les dépôts de cours d'eau en tresse à prédominance de sable ainsi que de conglomérats clastiques interprétés comme des dépôts de coulées de débris provenant de talus de failles voisins. Le faciès et l'âge présumé des affleurements de la Formation de Chedabucto sont semblables à ceux de la Formation de Wolfville dans le bassin secondaire Minas du bassin tectonique de Fundy. Ces faciès pourraient en outre être présents dans la partie inférieure de la Formation d'Eurydice à la base de la section sédimentaire du bassin marin d'Orphée. L'emplacement des affleurements de la Formation de Chedabucto laisse supposer qu'une ceinture continue de sédimentation à raccordé les bassins tectoniques d'Orphée et de Fundy au cours du Trias tardif, formant ainsi un large terrane qui s'étendait de l'Est du Nouveau-Brunswick è la Plate-forme Scotian. La Formation de Chedabucto a principalement ete deposed par un systeme riverain axial coulant en direction est du bassin tectonique de Fundy au bassin d'Orphée. Les chercheurs interpretent le bassin secondaire Minas du bassin tectonique de Fundy et le bassin d'Orph^e comme des segments d'un bassin de transition transversale formé par un mouvement oblique senestre synchrone s'étant exercé sur la faille de délimitation de Cobequid-Chedabucto. line inversion du bassin au cours du Jurassique moyen a probablement amorcé un soulèevement qui a entratné un isolement par erosion des bassins de Fundy et d'Orphée. [Traduit par la rédaction]Downloads
Published
1999-08-01
How to Cite
Tanner, L. H., & Brown, D. E. (1999). The Upper Triassic Chedabucto Formation, Guysborough County, Nova Scotia: depositional and tectonic context. Atlantic Geoscience, 35(2). https://doi.org/10.4138/2027
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