Marine Invertebrate Assemblages from the Late Pennsylvanian (Virgilian) Holder Formation, Dry Canyon, Sacramento Mountains, South-Central New Mexico
Marine invertebrate assemblages from the Late Pennsylvanian (Virgilian) Holder Formation, Dry Canyon, Sacramento Mountains, south-central New Mexico Barry S. Kues, Department of Earth and Planetary Sciences, MSC03 2040, University of New Mexico, Albuquerque, NM 87131-0001 Abstract Retispira–Polidevcia assemblage suggest Introduction abnormal marine conditions. The taxonomic The Holder Formation along Dry Canyon composition and relative abundances of taxa The Holder Formation, which crops out consists of a cyclic succession of Virgilian in this assemblage are unique in the Penn- along the western slopes of the Sacramen- marine siliciclastics, marine carbonates, and sylvanian of New Mexico and possibly of to Mountains, is one of the most intensive- nonmarine siliciclastics, including a large North America. The second assemblage, ly studied Pennsylvanian sedimentary basal algal bioherm complex, deposited on a from a transgressive interval of interbedded units in New Mexico. The formation was narrow shelf just west of the shoreline of the dark-gray shale and thin limestone 15–20 m Pedernal land mass. Holder marine inverte- (49–66 ft) above the first assemblage, consists named by Pray (1961) for essentially the brates have been little studied; here two of 100+ species from a wide assortment of Virgilian part of Thompson’s (1942) type quite different middle Virgilian assemblages marine groups, including gastropods (40+ Fresnal Group; the cyclic nature of Holder from an 80-m-thick (262-ft-thick) section species), brachiopods (24 species), bivalves strata was recognized by Cline (1959) and along US–82 are discussed. The first assem- (18 species), scaphopods, nautiloids, has been studied and related to correlative blage, from a 1-m-thick (3-ft-thick) dark-gray ammonoids, fusulinids, sponges, rugose basinal strata to the west (e.g., Wilson calcareous mudstone within a regressive corals, bryozoans, crinoids, echinoids, trilo- 1967); and its facies architecture and interval approximately 50 m (164 ft) above bites, ostracods, and fish teeth.
[Show full text]