Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 252, part 2
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Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 252, part 2
Prev Page--Introduction ||
Next Page--Kansas Stratotype
Conodonts have emerged as the predominant biostratigraphic fossil group used to define the Carboniferous-Permian boundary. The conodont succession at the Permian GSSP occurs in several other sections in the southern Ural Mountains, the midcontinent of the U.S.A. (Ritter, 1995, Boardman et al., 1998), in West Texas (Wardlaw and Davydov, 2000), and in China (Wang, 2000), as well as in many other intervening localities (Wardlaw, Davydov, et al., 2004).
In Kansas, the Carboniferous-Permian boundary, based on the first occurrence of the conodont Streptognathodus isolatus, is at the base of the Bennett Shale Member of the Red Eagle Limestone (Boardman et al., 1998; Wardlaw and Davydov, 2000; Sanderson et al., 2001; Wahlman and King, 2002; Olszewski and Patzkowski, 2003; Wardlaw, Boardman, et al., 2004). In most places the Bennett Shale Member is underlain by the Glenrock Limestone Member of the Red Eagle Limestone.
Thompson (1954) described the fusulinids from the Carboniferous-Permian boundary interval in Kansas (i.e., Admire, Council Grove, and Chase Groups). Subsequently, Douglass (1962), Baars, Ross, et al. (1994), Wahlman (1998, in press), Sanderson et al. (2001), and Wahlman and King (2002) discussed the fusulinid biostratigraphy of the boundary interval.
Baars, Ross, et al. (1994) used the first occurrence of the inflated fusulinid Paraschwagerina kansasensis to define the base of the Permian at the base of the Neva Limestone Member of the Grenola Limestone. However, in discussing the conodont work that was rapidly progressing at the time Baars, Ross, et al., 1994 (p. 7) recognized that "correlations are not yet firmly established in the Southern Ural Mountains of Russia and Kazakhstan" and "If an ammonoid or some other conodont zonation were to be employed in defining the basal Permian in the type area, the Pennsylvanian-Permian boundary may move eventually somewhat below the Neva Limestone Member."
Since the conodont-based assignment of the Carboniferous-Permian boundary, Wahlman (1998, in press), Sanderson et al. (2001), and Wahlman and King (2002) have discussed the fusulinid biostratigraphy of the boundary interval. The fusulinid assemblage in the Glenrock limestone, the rock unit immediately below the boundary, contains Triticites rockensis, Leptotriticites glenensis, and Schwagerina campa (Thompson, 1954). The first (i.e., next youngest) fusulinid assemblage above the Carboniferous-Permian boundary that has been described in Kansas is from the Neva limestone, approximately 14 m (46 ft) (Olszewski, 2000) above the Glenrock limestone. The Neva limestone fusulinid assemblage includes Paraschwagerina kansasensis, Schwagerina longissimoidea, and the three largest species of Leptotriticites (L. koschmanni, L. tumida, and L. obesa) (Thompson, 1954). The next higher fusulinid assemblages above the Neva limestone are from the Beattie Limestone (Cottonwood and Morrill Limestone Members) and include Schwagerina jewetti, S. emaciata, S. vervillei, Schubertella kingi, and Triticites sp. (Thompson, 1954).
Thus, fusulinids are transitional across the Carboniferous-Permian boundary in Kansas and are not accurate indicators of the boundary. However, several new species appear above the boundary and clearly define the earliest Permian (Nealian substage of the Wolfcampian Stage) in Kansas (G. P. Wahlman, personal communication, February 2006).
The most recent data on ammonoid assemblages from the upper Paleozoic in Kansas are contained in Boardman et al. (1994), who pointed out that ammonoids from the uppermost Virgilian and lowermost Permian in the northern midcontinent are poorly known (Boardman et al., 1994, p. 28). Ammonoid genera considered as zonal indices for the Virgilian and Asselian (Wolfcampian) stages are Shumardites and Svetlanoceras, respectively, but the former extends into the Asselian and the latter occurs only in the upper Asselian (Boardman et al., 1994, fig. 16). Other ammonoid genera that occur in the midcontinent are Kargalites, Daixites, Artinskia, Almites, Subperrinites, and Mescalites (Boardman et al., 1994, fig. 16). Mescalites discoidale and Eoasianites cf. E. subtilicostatus are both reported from the lowest limestone in the Hughes Creek Shale Member of the Foraker Limestone and from the upper part of the Bennett Shale Member of the Red Eagle Limestone in the northern midcontinent (Boardman et al., 1994, fig. 7). Prothalassoceras sp. also occurs in the lowest limestone in the Hughes Creek Shale Member and Subperrinites bakeri is reported from the Neva Limestone Member of the Grenola Limestone (Boardman et al., 1994, fig. 7). Subperrinites is a Permian genus, but Prothalassoceras extends into the Asselian from the Virgilian (Boardman et al., 1994, fig. 16). Ammonoids have not been reported from the interval between the base of the Howe Limestone Member of the Red Eagle Limestone and the top of the Salem Point Shale Member of the Grenola Limestone. Therefore, although ammonoids from Kansas exposures are indicators of the general Carboniferous-Permian boundary interval, they are not accurate indicators of the boundary horizon.
Barker (1983) and Barker and Eames (1988) studied palynomorphs from the Admire through Chase Groups (Permian) in Kansas. Ninety-four samples from a continuous core, the Amoco No. 1 Hargrave, were examined (Barker and Eames, 1988) (they did not examine samples from the Red Eagle Limestone and Roca Shale). Barker (1983) stated (p. 231) "the Admire assemblage is qualitatively transitional at the generic level and possesses miospore genera representative of the Upper Pennsylvanian through the Permian (Leonard); the limited occurrence of striate pollen in the Admire Group does not substantiate a Permian age; palynologically, a horizon somewhere between the Admire Group and the El Reno Group (of western Oklahoma) would be more appropriate." Barker (1983), Barker and Eames (1988), and Dunn (2001) recognized some of the same genera, but a meaningful comparison of these earlier data with those of Dunn (2001) would require an evaluation of the earlier taxonomy relative to that used by Dunn (2001). Such a re-evaluation might result in the recognition of the Limitisporites monstruosus-Vittatina costabilis assemblage zone as noted by Dunn (2001). At present, palynomorphs are not useful indicators of the Carboniferous-Permian boundary in Kansas.
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