A new Late Devonian ostracode fauna and its bearing on the Frasnian–Famennian boundary in western Canada

Abstract

A new ostracode assemblage, DFr6, characterizes the uppermost Frasnian rock sequences in western Canada. The assemblage or biozone contains elements of both the Frasnian and Famennian ostracode sequences and seems to be intermediate between both faunas, which in main aspects are strikingly different in composition. Similarities between the Devonian ostracodes of western Canada and their time-equivalent faunas of the Russian Platform and adjoining areas suggest the presence of a vast paleobiogeographic faunal province that is distinctly set apart from a "paleo-Tethyan" province whose ostracode representatives are found in central Europe and North Africa.The lower DFr6 subassemblage is contained in the Jean-Marie Member of the Redknife Formation, with the upper DFr6 ostracodes occurring in its upper member and in the Kakisa Formation. Both formations form prominent but lithologically similar carbonate sequences in the southwestern corner of the Northwest Territories and adjoining areas, causing problems in correlations, in particular in subsurface studies. Ostracodes of the upper DFr6 subzone were also recovered from the dolomites of the Winterburn Group of northern Alberta.

Late Devonian global ostracod palaeobiogeography

“…To obtain systematic and consistent data, the following rules on data selection have been borne in mind: (1) genus determination follows the taxonomy proposed by Moore (1961) in association with schemes proposed by Becker (1990Becker ( , 1999 and Lethiers & Feist (1991); (2) A raw data set from 17 operational geographical units (OGUs) were compiled for Frasnian ostracods (Table 1), and 20 OGUs were compiled for Famennian ostracods (Table 2), following the principles suggested by Crovello (1981). An OGU is a geologi- McGill (1963McGill ( , 1966, Lethiers (1978Lethiers ( , 1981, Braun & Mathison (1982), Braun & Lethiers (1982), Lethiers et al (1986), Braun (1967Braun ( , 1977Braun ( , 1978Braun ( , 1990; Becker & Braun (2008) 5 Appalachian Basin East USA Stewart & Hendrix (1945a,b), Duffield & Warshauer (1981), Knox & Gordon (1999) 6 Great Basin West USA Casier et al (1996, , 1998a Asturo-Leonese Basin Spain Michel (1972), Becker (1977), Becker et al (1979), van Loevezijn (1986), S anchez de Posada et al (2008) 10 Ardennes France Northern France Magne (1964), Lethiers (1970Lethiers ( , 1975, Milhau (1983) 11 Montagne Noire Southern France Lethiers & Casier (1994; Casier & Pr eat (2007) 12 Namur-Dinant Basin Belgium Casier (1977…”

“…The non-metric multidimensional scaling (NMDS) based on the Jaccard coefficient that superimposed the minimum spanning tree (MST) was performed by PAST with the purposes of Hou (1955), Shi (1964), Ji & Chen (1987), Wei (1988), Chen & Bao (1990), Zhao & Zhang (1997), Wang & Ma (2007), Wang (2009) Alberta Basin Northwest Canada Kindle (1919), McGill (1963), Lethiers (1978Lethiers ( , 1981, Braun & Mathison (1982), Braun & Lethiers (1982), Lethiers et al (1986), Braun (1990), Becker & Braun (2008) 4 Missouri River Basin Central USA Olempska & Chauffe (1999), Morey (1935Morey ( , 1936, Roth (1929) 5 Great Basin West USA Casier et al (1996), Casier & Lethiers (1998a) Asturo-Leonese Basin Spain Bless & Michel (1967), Michel (1972), Becker (1977), Becker et al (1979), van Loevezijn (1986); S anchez de Posada et al (2008) 9 Ardennes France Northern France Magne (1964), Lethiers (1970Lethiers ( , 1974aLethiers ( ,b, 1975, Casier & Pr eat (2003) 10 Montagne Noire Southern France Lethiers & Feist (1991), Lethiers & Casier (1994), Casier et al (2002a,b) 11 Namur-Dinant Basin Belgium Casier (1977Casier ( , 1979, Bless et...…”