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Tempo of Earliest Ordovician Graptolite Faunal Succession: Conodont-based Correlations from the Tremadocian of Quebec

TitleTempo of Earliest Ordovician Graptolite Faunal Succession: Conodont-based Correlations from the Tremadocian of Quebec
Publication TypeJournal Article
Year of Publication1986
AuthorsLanding, E, Barnes, CR, Stevens, RK
JournalCanadian Journal of Earth Sciences
Volume23
Pagination1928-1949
Keywordsgeology paleontology
Abstract

Successive Tremadocian planktic dendroid graptolite assemblages from continental slope sequences in Quebec can be correlated with North American platform biozonations on the basis of conodonts. Anisograptid-bearing (Assemblage 2), middle Tremadocian "Matane faunas" are associated with Early Ordovician Rossodus manitouensis Zone (new designation) conodonts. Younger middle Tremadocian faunas with adelograptids (Assemblage 3) are no younger than the Rossodus manitouensis Zone. Key dendroid evolutionary–immigration events take place within the lower conodont Fauna B interval. Rooted dendroids near Cap des Rosiers, Quebec, and in eastern New York State occur with lower Fauna B conodonts and the trilobites Pareuloma and Borthaspidella. However, the earliest Tremadocian (and earliest Ordovician) dendroid immigration event, represented by the local lowest occurrence of faunas with Dictyonema flabelliforme s.l. at localities in western Newfoundland, eastern New York State, Norway, and eastern China, also lies within the lower Fauna B interval. Finally, the lowest occurrence of key Assemblage 2 dendroid taxa falls within the lower Fauna B interval at the latter localities.The Rossodus manitouensis Zone is proposed as a new designation for a biostratigraphic unit that is appropriate for North American marginal and open shelf sequences. This zone is approximately equivalent to the "Loxodus bransoni Interval" of other authors and is characterized by Fauna C conodonts. Newly described taxa include Rossodus? highgatensis n. sp., Scolopodus? praecornuformis n. sp., and Variabiloconus n. gen.

URLhttp://www.nrcresearchpress.com/doi/abs/10.1139/e86-180#.Vo5q61K1Xgk
DOI10.1139/e86-180