Middle Ordovician To Silurian (wenlock) Conodont Taxonomy And Biostratigraphy From Basinal Strata Of The Road River Formation In The Richardson Mountains, Northern Yukon Territory

• Main Author: Mccracken, Alexander Duncan
• Format: Text
• Language: unknown
• Published: Scholarship@Western 1985
• Subjects: Paleontology; Richardson Mountains; Road River; Yukon; Mackenzie mountains
• Online Access: https://ir.lib.uwo.ca/digitizedtheses/1460; https://ir.lib.uwo.ca/context/digitizedtheses/article/2459/viewcontent/NL20703.PDF

Conodonts from fine clastics of the Road River Formation in the Richardson Mountains range from Middle Ordovician to Early Silurian. Additional Late Ordovician conodonts are from the more nearshore carbonate Whittaker Formation in the southern Mackenzie Mountains, N.W.T. Conodont faunas from the Road River Formation are largely represented by offshore and European Province taxa; faunas from the Whitaker Formation are dominated by Panderodus and American Province taxa. New or revised taxa include: Late Ordovician N. gen. A n. sp. A (differs from known rastrate taxa); Llandovery N. gen. B (may be related to Oulodus); and Astropentagnathus, which may have additional elements that comprise a symmetry series. Elements currently assigned to Carniodus may be part of Pterospathodus species; these are similar to elements of the older Llandovery P. posteritenuis. P. posteritenuis and the Ordovician G. ensifer may represent an evolutionary lineage.;Eleven Yukon conodont assemblages include: early Llanvirn "C." horridus - S. spinatus assemblage; P. serrus Zone (upper P. tentaculatus Zone, late Llanvirn); late Fauna 12 (Late Ordovician, P. pacificus Zone). Low abundance of Gamachignathus ensifer suggests the late Richmondian G. ensifer Biohorizon rather than Fauna 13 (Gamachian). The O. n. sp. A - I. sp. B assemblage lies between the P. pacificus and G. persculptus? zones. The O. fluegeli - D. obliquicostatus assemblage corresponds to the mid-M. turriculatus and the P. celloni zones, and probably represents an offshore fauna. Higher strata contain Aulacognathus bullatus, Astropentagnathus irregularis and Pterospathodus pennatus angulatus. The P. amorphognathoides Zone?, with Carniodus carnulus, Distomodus staurognathoides and P. p. procerus, occurs below the latest Llandovery C. sakmaricus - C. laqueus Zone; P. amorphognathoides is absent. The K. walliseri Biohorizon (Wenlock) is tentatively recognized.;Rare conodont-bearing carbonates, in contrast to common graptolitic shale demand that the systemic boundary in Yukon ...