A stratigraphical and faunal revision of the Ordovician–Silurian strata of the Percé area, Quebec

Publisher Website
Google Scholar
Abstract
The Ordovician - Silurian strata of the Perce area are assigned to the Matapedia Group. They occur in a southwestern monoclinial sequence, unconformably overlying Cambria strata, and are assigned to the Pabos and White Head formation. The Pabos Formation is preponderantly a terrigenous sequence, whereas the White Head is preponderantly a carbonate sequence. The Pabos strata of this area are included in the new Rouge Member, in which four brachiopod-dominated communities are recognized: the Dalmanella, Catazyga, Sowerbyella, and Epitomyonia communities, within which trilobites occur sporadically. The White Head Formation is divided into three new limestone members and a new mudstone member. The basal Burmingham Member has yielded a Catazyga Community and a Sowerbyella-like Community. The Cote de la Surprise Member is composed of mudstones with the previously described Hirnantia Community. The Rouge, Burmingham, and Cote de la Surprise members are Ashgillian (Upper Ordovician), but the uppermost two members of the White Head Formation, the L''Irlande and Des Jean members, are Llandoverian. They yield an Acernaspis Community, assigned a paleoecological position intermediate between those of the Clorinda and graptolite communities. The Matapedia Group limestones and shales in the structurally complex northeastern sequence are informally termed the Grande Coupe beds. These beds are partly or wholly time-correlative with the Rouge and Burmingham members but were deposited in deeper water. A Stenopareia Community includes the highly fossiliferous Grande Coupe beds, with a local development of the Foliomena Community. The Perce area is unique within the Quebec Appalachians because the strata of the Matapedia Group are highly fossiliferous, with distinct European affinities in the Ordovician, and because the monoclinal sequence is a deepening-upward sequence, probably to the north and west of deeper water clastics.