No abstract

The Jupiter and Chicotte formations, respectively 14-5 m and 23-33 m thick (Bolton, 1972), represent the youngest Silurian units on Anticosti Island. With the exception of informal member 2 (Bolton, 1972) of the Jupiter, they were sampled at 2-m intervals along their main sections. Sixty samples, averaging 2.0 kg in weight, yielded 5100 disjunct conodont elements. The Anticosti conodonts can be confidently assigned to the zonation established by Aldridge (1972) based on strata in the Welsh Borderland. Thus, the sample from about 10 m above the base of member l of the Jupiter Formation is in the highest part of the Icriodella dis ere ta-I. de flee ta Zone (C 2, Fronian age). The remainder of the Jupiter, up to 2 m below the top of the formation, is assignable to the Distomodus staurognathoides Zone (C2 to C4, Fronian to early Telychian). In the Anticosti Island succession, this zone can be further subdivided into two informal units: the lower staurognathoides fauna (C 2, mid-Fronian) and the higher aldridgei fauna (C 3 - 4, late Fronian-early Telychian), with the separation occurring about 17 m above the base of member 4-. The interval including the uppermost 2 m of the Jupiter and up to 24- m above the base of the Chicotte Formation, belongs to the Icriodella inconstans Zone (C 5 , Telychian). The Pterospathodus celloni Zone of Walliser (1964-) probably represents an upper part of this zone. The Pterospathodus amorphognathoides Zone (C 6 , late Telychian-early Wenlock) is present in the sample 24- m above the base of the Chicotte. Although the zone straddles the Llandovery-Wenlock boundary, the stratigraphic position of this sample suggests that it is probably still of late Telychian age. Two of Cooper's (1980) Datum Planes are represented: the Distomodus staurognathoides Datum in member l of the Jupiter Formation, and the Pterospathodus amorphognathoides Datum in the Chicotte Formation.

A conodont fauna consisting of ten species and seven form - species is described from the Hull Formation of the Ottawa Group of the Ottawa-Hull area in Ontario and Quebec. The collection of over 10,000 specimens indicates that the Hull conodont fauna is typical of the North American Midcontinent Province, and of the eastern subprovince (Barnes et al. , 1973) , and may be assigned to Fauna 8 of Sweet et al. (1971 ) . In New York and Ontario, Fauna 8 ranges from the uppermost part of the Chaumont Formation to the mid- part of the Kings Fall s Limestone (Schopf , 1966; Sweet et al , 1971) . In terms of North American s t ages, Fauna 8 is of late Porterfieldian through mid-Kirkfieldian age, or approximately late Wlildernessian (Bergstrtlm, 197lb). The Hull Formation is redefined in litho stratigraphic terms.

The cratonic Boothia Uplift constitutes a major geological province in the Canadian Arctic. It is 800 km long and 150 km wide and extends from Boothia Peninsula on the continental mainland to about the geographic centre of the Canadian Arctic Archipelago. Rocks of Precambrian and Phanerozoic ages are included in the Uplift. The principal crustal movements by which the uplift achieved its present areal extent and many of its present structural characteristics occurred in Late Silurian and Early Devonian times. These movements exerted a profound influence on local sedimentation, effecting complex and diverse facies changes that have necessitated the establishment of different formational successions in rocks of Late Silurian to Early Devonian ages in most of the major islands and Boothia Peninsula that comprise the uplift. Uncertainty has surrounded the ages of several formations within this interval of time, and this has precluded a clear understanding of correlations, as well as the timing and areal extent of the crustal movements that produced the Boothia Uplift. The present study deals mainly with the lithe- and biostratigraphy of Upper Silurian to Lower Devonian rocks in the environs of the Boothia Uplift. It commences with the Upper Silurian Cape Storm Formation which was deposited shortly before the onset of crustal movements in the Boothia Uplift in Paleozoic time and ends with the Lower Devonian Disappointment Bay Formation that lies with angular unconformity on the bevelled and truncated rocks of the uplift, and thus provides a firm upper age limit to principal crustal movements that produced the uplift. Much new information is provided on the ages of the various Upper Silurian to Lower Devonian formations in the environs of the uplift, and this is based largely on the study of conodonts (by T.T. Uyeno) and graptolites. The present study has also indicated a need for revisions to the formational nomenclature of rocks in the report area. The Cape Storm Formation is now recognized in the Cornwallis Island area where its basal part is made up of beds included previously in the Allen Bay Formation while its upper part includes beds assigned previously to the lower part of member A of the Read Bay Formation. The remainder of member A, as defined in Cornwallis Island, is herein assigned to the Douro Formation. Rocks referred to the Read Bay Formation in Somerset and Prince of Wales Islands and Boothia Peninsula, and those formerly included in the lower part of the Read Bay in Devon Island are assigned also to the Douro Formation. The rocks formerly considered as members B and C of the Read Bay Formation are included in a single formation for which the new name Barlow Inlet is proposed, whereas member D, which previously constituted the uppermost part of the Read Bay Formation is raised to the rank of formation and given the name Sophia Lake. The Read Bay Formation is raised to the status of group, and includes in order upward the Douro, Barlow Inlet and Sophia Lake Formations. As so defined, the Read Bay Group is distributed only in the Cornwallis Island area and adjacent parts of Devon Island. Southern and northern parts of the Boothia Uplift, which are separated by Barrow Strait, are characterized by different deformational histories within the Late Silurian to Early Devonian interval of time. Diastrophism commenced south of the strait (Somerset and Prince of Wales Islands, and Boothia Peninsula) in the late Ludlovian, whereas north of the strait (Cornwallis Island, northwestern Devon Island, and eastern Bathurst Island), it commenced in the early Lochkovian. From the early Lochkovian to the early Zlichovian, diastrophism appears to have proceeded simultaneously in both parts of the uplift.

A succession of Devonian strata, ranging in age from Pragian? to Famennian and possibly postFamennian, occurs in southwestern Ontario. The Lower Devonian sequence comprises the sandstone of the Oriskany Formation (Pragian?), cherty dolomitic limestone of the Bois Blanc Formation (robust us Zone , and possibly equivalent to the serotinus Zone; Emsian), the bioclastic limestone of the Amherstburg Formation (possibly serotinus to patulus Zones; Emsian?) and the lithologically variable Lucas Formation. The latter two units form the Detroit River Group. The sandy limestone facies ("Columbus limestone"), developed within the Anderdon Member of the Lucas Formation, contains conodonts of the patulus Zone (undivided). Pending the final decision, the Lower-Middle Devonian boundary lies very close to the patulus Zone, and therefore to the Anderdon Member. In the Niagara Peninsula, New York nomenclature is applicable, and parts of the Onondaga Formation are recognized (in ascending order): Edgecliff, Clarence, and Moorehouse Members. The true relationship of the Onondaga and the Detroit River is still not entirely known. At the base of the Middle Devonian sequence is the fossiliferous, micritic limestone of the Dundee Formation which lies disconformably on the Detroit River strata. Dundee conodonts are assignable to the costatus costatus, australis and kockelianus Zones, of Eifelian age. The overlying Hamilton Group, studied only in outcrop sections, includes the upper part of the Arkona Formation (shale), and the Hungry Hollow (shale and limestone), Widder (shale), and Jpperwash (jimestone) Formations. The conodonts of this upper part of the Hamilton belong to the Lower varcus Subzone of Givetian age. The lower part of the Hamilton may possibly contain conodonts of the ensensis Zone, which straddles the Eifelian-Givetian boundary. The Upper Devonian black shales of the Kettle Point Formation lie disconformably on the Ipperwash Formation. Kettle Point conodonts are assignable to the Middle asymmetricus Zone to possibly the costatus Zone (Winder, (966), thus demonstrating that almost the entire Upper Devonian (ranging in age from early Frasnian to late Famennian) is represented in the subsurface. The Devonian conodonts of southwestern Ontario were among the earliest to be studied in North America (Hinde, 1879; see also Bergstrom and Hansen, 1979). In the present study, one new species, Icriodus hankae, is introduced.