Late Devonian (Frasnian and Famennian) conodonts from the Wadleigh Limestone, southeastern Alaska

• Published in: Journal of Paleontology
• Main Author: Savage, Norman M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1992
• Subjects: Northwest Territories; Alaska
• Online Access: http://dx.doi.org/10.1017/s0022336000033795; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022336000033795

Conodont faunas from the upper part of the Wadleigh Limestone, Alexander terrane, southeastern Alaska, are of Frasnian to early Famennian age and include the new taxa Polygnathus aspelundi nanus n. subsp., Polygnathus decorosus dutroi n. subsp., Polygnathus elegantulus sparus n. subsp., Polygnathus gracilis n. subsp. A, Polygnathus n. sp. A, Palmatolepis subrecta youngquisti n. subsp., and Icriodus subterminus uyenoi n. subsp. Four distinct age-determined faunal assemblages are recognized. The lowest is assigned to the Lower Palmatolepis rhenana Zone (the chronozones of Ziegler and Sandberg, 1990, are treated herein as time-rock equivalent assemblage zones). The next is exposed on three small islands just south of Wadleigh Island and is correlated with part of the Lower to Upper Palmatolepis rhenana Zones. The third assemblage, on the eastern side of Wadleigh Island from close to the top of the section, is correlated with part of the Palmatolepis linguiformis Zone. Nearby and overlying this is the fourth assemblage, which is correlated with part of the Lower Palmatolepis triangularis Zone and thus appears to be within the lower Famennian. These Wadleigh Limestone conodont faunas have affinities with faunas from equivalent horizons of the cratonic regions of the Northwest Territories and Alberta in Western Canada and to other faunas globally. The more provincial conodont taxa lend weak but positive support to brachiopod faunal evidence that places the Alexander terrane close to the North American craton during the Late Devonian.