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

Abstract

The Ordovician–Silurian strata of the Percé area are assigned to the Matapédia Group. They occur in a southwestern monoclinal sequence, unconformably overlying Cambrian strata, and are assigned to the Pabos and White Head formations. 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 Côte de la Surprise Member is composed of mudstones with the previously described Hirnantia Community. The Rouge, Burmingham, and Côte 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 Matapédia 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 Percé area is unique within the Quebec Appalachians because the strata of the Matapédia 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.

Chapter 9 Coral biogeography in the Late Ordovician (Cincinnatian) of Laurentia

“…Some areas inhabited by the 'Continental Margin' fauna were geologically stable. North of the Taconic Upland, platformal carbonates and minor siliciclastics accumulated in the Anticosti Island area Long 2007), with more distal deposits in the Percé area (Lespérance et al 1987;Malo 2004). Within the latter area, corals apparently lived at moderate depths corresponding in position to brachiopod Benthic Assemblage 4 (Lespérance et al 1987).…”

“…The effects of such upwelling extended into the cratonic interior east of the Transcontinental Arch, where mainly argillaceous sediment in the depositional area of the Maquoketa Group was derived from the Taconic Upland to the east (Kolata & Graese 1983). Along the continental margin north of the Taconic Upland, platformal carbonate deposition with minor siliciclastic input occurred in the Anticosti Island area Long 2007) and distally in the Percé area of eastern Québec (Lespérance et al 1987;Malo 2004). …”

“…North of the Taconic Upland, platformal carbonates and minor siliciclastics accumulated in the Anticosti Island area Long 2007), with more distal deposits in the Percé area (Lespérance et al 1987;Malo 2004). Within the latter area, corals apparently lived at moderate depths corresponding in position to brachiopod Benthic Assemblage 4 (Lespérance et al 1987). South of the Queenston Delta Complex, shallow-shelf, mixed carbonate -siliciclastic deposition occurred in northwestern Georgia and north-central Alabama (Chowns & McKinney 1980).…”

Deep shelf trilobite biofacies from the upper Katian (Upper Ordovician) of the Grangegeeth Terrane, eastern Ireland

“…During the Late Ordovician, however, cyclopygids became increasingly common in low latitude deep water environments on and adjacent to the Laurentian margin, being recorded from North America (e.g. Lespérance et al ., 1987; Owen and Bruton, 2008), SW Scotland (Ingham in Thomas et al ., 1984; Rushton et al ., 1996; Stewart and Owen, 2008), the Central Terrane in Ireland (Weir, 1959) and, based on hitherto limited sampling, the enigmatic Grangegeeth Terrane in eastern Ireland (Romano, 1980). Here we document the cyclopygid and associated benthic trilobite fauna from the upper Katian Oriel Brook Formation in the Grangegeeth Terrane based on our much more extensive samples than those available for the compilation of the faunal list in Romano (1980).…”

“…During the Late Ordovician, however, cyclopygids became increasingly common in low latitude deep water environments on and adjacent to the Laurentian margin, being recorded from North America (e.g. Lespérance et al, 1987; been the subject of considerable controversy. Owen et al (1992) summarized the debate to that point and argued that the early Caradoc (Sandbian in terms of the modern international Ordovician chronostratigraphy) trilobites and brachiopods showed marked Scoto-Appalachian/Laurentian affinities.…”