A RADIOLARIAN ASSEMBLAGE FROM THE PENNSYLVANIAN (DESMOINESIAN) EXCELLO BLACK SHALE OF SOUTH-EASTERN KANSAS, USA

Assemblages of conodonts, foraminifers, fish remains and radiolarians in phosphatic and calcareous concretions occur in Paleozoic through Triassic strata in many places of the world. In the United States calcareous concretions with microfossils have been reported from the Ordovician (Nevada), Devonian (Ohio), Mississippian (Texas and Utah), Pennsylvanian (Iowa and Kansas), Permian (Utah and Idaho), and Triassic (Idaho). In Iowa, a rich radiolarian assemblage was recently described by Nestell et al. from carbonate concretions of the Excello Shale (Marmaton Group, Desmoinesian, Pennsylvanian) near the towns of Booneville and Medora. Radiolarians are very abundant and occur with a very well preserved conodont assemblage of species of Idiognathodus, Idioprioniodus, Neognathodus (N. roundyi) and Gondolella. In south-eastern Kansas radiolarians were first reported by Nodine-Zeller et al. in 1979 from phosphate nodules of the Cherokee and Marmaton Groups of the Desmoinesian, and the Pleasanton Group of the Missourian. These radiolarians were studied only in thin sections because their tests could not be extracted from the nodules. A new radiolarian fauna from the Excello Shale occurs in carbonate concretions found in road cuts along US Hwy 69 about 35 miles south of Fort Scott in south-eastern Kansas. The radiolarian assemblage contains new species of the genera Palacantholithus, Albaillella, Pseudoalbaillella, Entactinia, Haplentactinia, Quadriremis, Pseudotormentus, and the species Spongentactinia? incerta. The assemblages of radiolarians from the Excello Shale of Iowa and Kansas are very different in their generic and specific composition. Only Spongentactinia? incerta and one species of Pseudoalbaillella are common to the two assemblages. The diverse Iowa conodont fauna indicates that the site of the deposition of the concretion-bearing interval probably was on the boundary between the thermocline and a warm surface layer. Conodonts in the Kansas assemblage are rare, represented by juvenile forms of Idiognathodus and Neognathodus. The Kansas location was much farther offshore (450 km basinward) compared to the Iowa localities, suggesting a difference in upwelling and thermocline depth affecting water temperature, oxygenation and nutrients.