Taxonomy and biostratigraphy of upper Guadalupian radiolaria from the Reef Trail Member of the Bell Canyon Formation, Guadalupe Mountains National Park, West Texas, USA.

摘要

Radiolarian fauna recovered from several intervals of the Reef Trail Member of the Bell Canyon Formation located in the Patterson Hills in Guadalupe Mountains National Park represent a biostratigraphically significant and diverse assemblage comprising at least 48 species including 21 new taxa. The Reef Trail Member represents end Guadalupian deposition in the Delaware Basin as determined by co-occurring conodont fauna, namely Clarkina postbitteri hongshuiensis Henderson, Mei, and Wardlaw, which occurs in the upper beds of the Patterson Hills section. These fauna are significant because they comprise new species of Pseudoalbaillella, which is a biostratigraphically significant component of any Guadalupian assemblage and may be useful in regional correlation in the Glass and Apache Mountains. It is not known if the new species of Pseudoalbaillella will be useful in global correlation as they have not been recognized in Guadalupian strata elsewhere. This assemblage contains the oldest known appearance of Albaillella yamakitai, which only appears above the Guadalupian-Lopingian boundary in coeval rocks in China and Japan. Albaillella yamakitai may have evolved proximal to the North American continent and may serve as a valuable indicator of uppermost Guadalupian strata in North American terranes. Sixteen species of Latentifistularia are described including 5 previously undescribed species. The biostratigraphic significance of Latentifistularia has been underestimated in Permian strata and these fauna are useful for global and regional correlation. Nineteen Spumellaria and Entactinaria are described thirteen of which are previously undescribed. Most radiolarian studies do not describe the spherical radiolarian component so the stratigraphical ranges of many species are not known. By describing the Entactinaria and Spumellaria in the Reef Trail Member it will be known if any of these new species may be useful in regional and/or global correlation. Many of these fauna occur in coeval strata in the Apache Mountains located in the southern part of the Delaware Basin, however several fauna are absent which is problematic since similar conodont faunas have been recovered from these intervals. It is likely that variations within the assemblages may be a result of localized paleoenvironmental fluctuations.