Geological map and notes on the Ordovician and Silurian Lith- and Biostratigraphy, Anticosti Island, Quebec

Abstract

The six formations detailed on the preliminary geological map of Anticosti Island, Quebec, represent an uninterrupted sequence of nearly flatlying rocks of Upper Ordovician to Middle Silurian ages. The Upper Ordovician strata, divisible into two formations, Vaureal and Ellis Bay, are persistent, alternating calcareous and argillaceous units, each bearing distinct marine faunal assemblages. These rocks occupy the northwestern one-third of the island. The succeeding Lower and Middle Silurian strata of the Becscie, Gun River and Jupiter Formations are more variable lithological units, the upperrnost Chicotte Formation, occurring only along the southern coast of the island, being everywhere a massive, crinoidal limestone. These Silurian formations, of Llandoverian and early Wenlockian ages (Alexandrian and early Niagaran), are highly fossiliferous and divisible into several tentative faunal units. Characteristic fossils from each of the six formations are illustrated in a preliminary fashion and grouped by formation.

Late Ordovician–Early Silurian (Ashgillian–Llandovery) sea level curve derived from conodont community analysis, Anticosti Island, Québec

“…The stratigraphic subdivisions for Vaure ¤al, Ellis Bay, Becscie, Merrimack, Gun River, Jupiter and Chicotte formations in this study are mainly based on Bolton (1972), Petryk (1981a) and Uyeno and Barnes (1983). More recent subdivisions for the uppermost Vaure ¤al and Ellis Bay formations (Long and Copper, 1987), Becscie and Merrimack formations (Copper and Long, 1989), and Jupiter Formation (Copper and Long, 1990) have been formally published ( Fig.…”

“…Under Member 1 , the formal member names are shown in regular font, which is based on Long and Copper (1987) and Long (1989, 1990) (LC = Lousy Cove M.; P = Prinsta M.; V = Velleda M.); the informal member names are shown in italic font, which are from Copper and Long (1998); under Member 2 , the upper and lower members of the Vaure ¤al Fm. are from Bolton (1972) and Nowlan and , members 1^6 of Ellis Bay Fm. are from Bolton (1972) (member 6 includes only the lower 2m of the member as originally de¢ned), members 1^4 of Jupiter Fm.…”

“…are from Bolton (1972) (member 6 includes only the lower 2m of the member as originally de¢ned), members 1^4 of Jupiter Fm. are from Bolton (1972) and Uyeno and Barnes (1983) with others from Petryk (1981a). new; (4) 60 samples from the Jupiter and Chicotte formations that contain over 5 000 conodont elements representing 33 multielement species (Uyeno and Barnes, 1983), most of which are di¡erent from those in the underlying Becscie, Merrimack and Gun River formations. In summary, the total database includes 272 samples that yielded over 77 600 conodont elements referred to 83 di¡erent species.…”

“…Detailed studies of Late Ordovician and Early Silurian stratigraphy, sedimentology, and macrofaunas on Anticosti Island have been undertaken by Bolton (1972; includes a summary of earlier work), Barnes et al (1981), Petryk (1981a), Lespe ¤rence (1981), Barnes (1989), Sami and Desrochers (1992), Copper and Long (1998), Jin and Copper (1999) and Dewing (1999). From the combination of stratigraphy, sedimentology, and faunal communities, various attempts have been made to establish a sea level curve for all or parts of this interval.…”

La morphogénèse de la caverne à la Patate, île d’Anticosti, Québec

“…Cette formation ordovicienne présente de nombreux faciès (BOLTON, 1961(BOLTON, , 1972PETRYCK, 1981). Sur ABSTRACT Morphogenesis of the Caverne à la Patate, Anticosti Island, Québec.…”