Abundant conodont faunas from the Olenekian (Early Triassic) of subsurface British Columbia, Canada and diversification of the Neogondolellinae around the Smithian–Spathian boundary

Abstract

Abundant conodont faunas from the subsurface of British Columbia, Canada, allow the correlation of Lower and Middle Triassic strata with outcrop sections in British Columbia, the Canadian Arctic and the western USA, as well as recording the previously recognized radiation of neogondolellin conodonts in the early Spathian. Twenty-eight samples collected from the Progress Hz Caribou D-040-H/094-G-07 and Progress Hz Laprise A-082-I/094-G-01 wells yielded more than 1100 conodont specimens, representing twenty-nine pectiniform species belonging to fourteen genera. These faunas enable the recognition of the Dienerian–Smithian, Smithian–Spathian, and Spathian–Anisian boundaries in these wells. Five of the conodont species recognized in the Smithian and Spathian samples are new: Neogondolella n. sp. A, Borinella n. sp. A, Magnigondolella. n. sp. A, Columbitella n. sp. A, and Co. talpa sp. nov. Together with these new segminiplanate species, several other neogondolellin conodonts occur. These faunas are the manifestation in British Columbia of the previously recognized increase in abundance of neogondolellin conodonts in the early Spathian, and they are consistent with hypotheses in which the earliest species of Magnigondolella evolved from Borinella by a progressive fusion of the denticles of the carina. These conodonts help to characterize the events around the globally significant Smithian–Spathian boundary, and to correlate this boundary in North America.