The sedimentology and tectonic significance of Devonian and Carboniferous terrestrial successions in Gaspé, Quebec

Authors

  • Brian R. Rust Geology Department, University of Ottawa and Ottawa-Carleton Geoscience Centre,Ottawa, Ontario KIN 6N5, Canada
  • David A. Lawrence B.P. Petroleum Development Limited, Britannic House, Moor Lane, London EC2Y 9BU, United Kingdom
  • Brian A. Zaitlin Esso Resources Canada Limited, Calgary, Alberta T2P 0H6, Canada

DOI:

https://doi.org/10.4138/1666

Abstract

The 5 km-thick mid-Gaspé Devonian clastic wedge coarsens upwards from the shallow marine York River Formation through the Battery Point Formation (distal to proximal sandy alluvium) to gravelly proximal alluvium of the Malbaie Formation. Paleoflow was consistently northward, away from the rising Acadian mountains, but axial drainage switched from westward (York River, Lower Battery Point) to eastward (upper Battery Point, Malbaie) as the elevated source area migrated westward. This is attributed to dextxal shearing of the North American continental margin due to collision between Avalonia and die Sl Lawrence Promontory. Continued dextral shear ultimately caused impact between Avalonia and the New York Promontory, producing the Catskill wedge. In contrast, Devonian sediments in southern Gaspé are confined to smaller intermontane basins, with a mean southward paleoflow. The deposits comprise proximal alluvium (Lagarde, Pirate Cove, Fleurant Formations) and lacustrine sediments (Escuminac Formation). In contrast with the broad Devonian clastic wedge. Carboniferous sediments in Gaspé predominantly accumulated on alluvial fans. Fan deposition is attributed to fault tectonics, predominantly dextral strike-slip along the Fundy Rift Zone as the inboard margin of Avalonia locked with the New York Promontory. However, Gaspé was peripheral to the main location of Carboniferous strike-slip shearing, and appears to have been mainly influenced by dip-slip faulting. RÉSUMÉ LaMoyerme-Gaspésie recèle un prisme déritique dévonien granocroissant de 5 km d'épaisseur comprenant, de bas enhaut, la Formation littorale de York River, la Formation de Battery Point (alluvions sablormeuses distales à proximales) et les alluvions graveleuses proximales de la Formation de la Malbaie. L'écoulement demeura consistant vers le nord, en s'éloignant des montagnes acadiennes qui étaient alors en cours de surrection, mais le drainage axial vira de l'ouest (York River, Batterie Point inférieure) vers Test (Batterie Point supérieure, Malbaie) durant la migration vers l'ouest du relief nourricier. On attribue ceci à un cisaillementdextre de la marge continental nord-américaine par suite d'une collision entre Avalonia et le Promontoire du Saint-LaurenL Le résultat ultime d'un cisaillement dextre soutenu fut L’impact d'Avalonia sur le Promontoire de New York, ce qui engendra le prisme de Catskill. En revanche, les sédiments dévoniens de la Gaspésie méridionale sont confinés à des bassins intramontagneux plus restraints, avec un paléocourant moyen vers le sud. Les dépôts comprennent des alluvions proximales (formations de Lagarde, Pirate Cove et Fleurant) et des sédiments lacustres (Formation d'Escuminac). A l’opposé du vaste prisme détritique dévonien, les sédiments carbonifères gaspésiens s'accumulérent en majorité sur des cônes de déjection. On attribue ce type de dépôt à une tectonique de failles, principalement à un décrochement dextre le long du Couloir de Fundy lors du blocage de la marge interne d' Avalonia sur le Promontoire de New York. Cependant, la Gaspésie se trouvait en périphérie du site principal de dérochement lié au cisaillement carbonifère; elle semble avoir subi surtout un jeu selon le rejet-pente. [Traduit par le journal]

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Published

1989-04-01

How to Cite

Rust, B. R., Lawrence, D. A., & Zaitlin, B. A. (1989). The sedimentology and tectonic significance of Devonian and Carboniferous terrestrial successions in Gaspé, Quebec. Atlantic Geoscience, 25(1). https://doi.org/10.4138/1666

Issue

Vol. 25 No. 1 (1989)

Section

Articles

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