Record of Late Frasnian Kellwasser Extinction Bioevents, Terminal Frasnian Upper Kellwasser Crisis Fauna, and Early Famennian Post-Extinction Recovery: Alberta Rocky Mountains

Most North American late Frasnian to early Famennian platform records of the Upper Kellwasser extinction bioevent (UKW) are incomplete because of platform emergence and erosion. However, faunas from this interval are preserved in off-reef slope (Thornton Pass) and basinal (Marmot Crack) successions in the vicinity of the Ancient Wall detached reef platform in Jasper Park, western Alberta. The Lower Kellwasser bioevent (LKW) is recorded by extinction of a significant number of species characteristic of the late Frasnian deeper water Mount Hawk and upper Arcs Mb-Southesk Fm. carbonate ramp faunas (Rigauxia, Coeloterorhynchus, Douvillina, etc.). Late Frasnian deepening and platform drowning coincident with the LKW, is followed by Simla carbonate ramp progradation. Simla ramp facies contain very late Frasnian middle (Thornton Pass) and outer ramp (Marmot Crack) shelly faunas associated with Montagne Noire Zone 13 conodonts. LKW carryover species of Costatrypa, Pseudoatrypa, Spinatrypa, Schizophoria, Floweria, Hypothyridina, Gypidula, Theodossia, Cyrtopirifer, Conispirifer, characteristic of the western Canadian Theodossia scopulurum Zone of Raasch and Russian immigrants such as Spinatrypina (Exatrypa). The Upper Kellwasser extinction interval is in the uppermost Simla in the Thornton Pass section. There uppermost Frasnian conodonts occur with brachiopods including Cyrtospirifer sp. cf. C. minor, Leioproductus sp., Ripidiorhynchus sp., C. sp. cf. C. whitneyi, Praewaagenoconcha sp.. Only the latter two are known from North America whereas the other genera are known from pre-UKW faunas in the Polish and Russian platforms. Cosmopolitan pan-tropical Early Famennian survivor and early recovery faunas were discovered in oncoid debris flow deposits of the lower Sassenach Formation that includes: Praewaagenoconcha sp., Leioproductus sp., large productoid-new genus, Crinasarina angelicoides, Sinospirifer portae, and reworked late Frasnian shells of Pseudoatrypa sp. The post-UKW recovery is well underway during the early Famennian L.-M. triangularis Zone as evidenced by increased diversity of recovery faunas in the lower Sassenach and coeval units of Eurasia.