Age of the Ogilvie Formation (Devonian), Northern Yukon: Based Primarily on the Occurrence of Brachiopods and Conodonts

Abstract

The Ogilvie Formation, formerly dated as Eifelian and Givetian, is locally confined to the Early Devonian, Emsian. Regionally the top of the Ogilvie is markedly diachronous ranging in age from Emsian to Givetian. The Ogilvie Formation conformably overlies the Late Silurian to Early Devonian Gossage and/or early Emsian Michelle and Cranswick Formations. The stratigraphic thickness of the Ogilvie varies from 200–3500 ft (61–1068 m) over relatively short geographic distances. The ages of the lower and upper beds of the Ogilvie are based on brachiopods, conodonts, corals, and trilobites. Locally, the lower part of the overlying unnamed shale unit is regarded as a lateral equivalent to parts of the younger Ogilvie carbonate sections. The Eifelian age of the basal beds of the unnamed shale unit is derived from a few strategically located dacryoconarid tentaculite collections. The Ogilvie Formation is a shallow water carbonate shelf deposit, locally reefal, which had its most extensive development in the later part of the Emsian. From the later part of the Emsian through Givetian, the carbonate shelf was gradually inundated by shales until in the late Givetian only a very small area of carbonate deposition remained in the western Yukon (Mount Burgess).The brachiopod affinities lie with the Cordilleran Subprovince of the Old World Province and with forms of similar age described from central Nevada. The conodonts and trilobites are correlative with forms from Arctic Islands, eastern Alaska, and Nevada. The Emsian tetracoral fauna is similar to that of the Emsian of eastern Australia whereas the Eifelian fauna is similar to that of other parts of northwestern Canada.Five informal conodont faunal units, ranging in age from Emsian through Eifelian, are proposed for the Michelle–Ogilvie sequence. In addition, the P. varcus Zone (Givetian) is recognized at the top of the Ogilvie at one section.

Lower-Middle Devonian (upper Emsian-Eifelian, serotinus-kockelianus zones) conodont faunas from the Prague Basin, the Czech Republic

“…aff. P. trigonicus with the lower part of the costatus Zone in the Prague Basin, as elsewhere ( , Perry et al 1974. Both that species and P. c. costatus occur close to the base of the Choteč Limestone, which reflects the effect of the Basal Choteč event.…”

“…aff. P. trigonicus is characteristic for the base of the costatus Zone, not only in the Prague Basin but also elsewhere ( , Perry et al 1974). For the above-mentioned reason, the base of the costatus Zone in the Na Škrábku quarry section is drawn according to the FAD of this taxon.…”

The first stringocephalid brachiopods in the upper Givetian of Selennyakh Range (Northeast Asia) and their paleobiogeographical significance

“…A considerable number of publications exist on stringocephalid brachiopods published in the same year or subsequent to the salient paper of Boucot et al (1966). These include reports from such geographic areas as Vietnam (Thanh and Khuc, 2006), Malaysia (Gobbett, 1966), South China (Sun and Bai, 1995;Sun and Boucot, 1999;Wang et al, 1974Wang et al, , 1987Xian, 1998;Xian and Jiang, 1978;Yang, 1983), Uzbekistan (Smirnov, 1985), Russia (Khodalevich, 1975), North Africa (Schemm-Gregory and Jansen, 2008), Germany (Struve, 1982(Struve, , 1992, Poland (Balinski, 1971(Balinski, , 1973Balinski et al, 2000;Halamski and Segit, 2006;Racki, 1992), Czech Republic (Ficner and Havlíček, 1975), northern Mexico (Sonora) (Boucot et al, 2008), western Canada (Crickmay, 1967(Crickmay, , 1968Johnson, 1969Johnson, , 1973MacKenzie et al, 1975;Perry et al, 1974); Nevada (Frost and Langenheim, 1966;Johnson, 1969Johnson, , 1973Johnson, , 1974Johnson et al, 1980aJohnson et al, , 1980bSchemm-Gregory and Jansen, 2009), Utah (Johnson, 1973), Indiana (Cooper and Phelan, 1966), and Pennsylvania (Johnson, 1969). Nearly all members of the family Stringocephalidae are paleobiogeographically known only from the tropical to subtropical Old World Realm…”

Brachiopods from Bird Fiord Formation (Devonian) of Arctic Canada

“…15.1-15.23) Spirifer scheii Meyer, 1913, pp. Perry et al 1974Perry et al , p. 1077Jones and Smith, 1980, p. 689, pl. 5, fig.…”