SAETOGRAPTUS ARGENTINUS ARGENTINUS AND S. A. ROBUSTUS (GRAPTOLITHINA; EARLY TO LATE LUDLOWIAN) FROM THE LOS ESPEJOS FORMATION, CENTRAL PRECORDILLERA OF SAN JUAN, ARGENTINA
DOI:
https://doi.org/10.5710/PEAPA.09.07.2022.427Keywords:
Graptolites, Saetograptus, Ludlow, Silurian, PrecordilleraAbstract
Two subspecies of S. argentinus are described in Silurian levels from the Central Precordillera of San Juan, Argentina. The studied samples come from the middle to upper part of the Los Espejos Formation at the quebrada Ancha section, Talacasto area. The bearing beds consist of coquinas with clay-carbonate cement or calcarenites. Specimens of Saetograptus argentinus argentinus and S. a. robustus, in association with brachiopods, bivalves, trilobites, tentaculitoids, and ostracods, are present in the samples. The mentioned graptolite fauna, together with previous conodonts and brachiopods biostratigraphic data, allow to assign a Ludlow age for these levels. Subspecies of Saetograptus argentinus are described for the first time in the Precordillera Geological Province and enable to correlate the quebrada Ancha section with Cerro del Fuerte, La Chilca, and Loma de Los Piojos sections in Precordillera, and with Kirusillas Formation in Bolivia.
References
Albanesi, G. L., Ortega, G. y Hünicken, M. A. (2006). Bioestratigrafía de conodontes y graptolitos silúricos en la sierra de Talacasto, Precordillera de San Juan, Argentina. Ameghiniana, 43(1), 93–112.
Barrande, J. (1850). Graptolites de la Bohême. Extrait du Systême Silurien du centre de la Bohême. Published by the author, Prague, 74, 4 pls.
Benedetto, J. L., Racheboeuf, P. R., Herrera, Z., Brussa, E. D. y Toro, B. A. (1992). Brachiopodes et biostratigraphie de la formation de Los Espejos, Siluro–Devonien de la Precordillere (NW Argentine). Geobios, 25(5), 599–637.
Benedetto, J. L. y Sánchez, T. M. (1996). The ‘Afro-South American Realm’ and Silurian Clarkeia Fauna. In: Copper, P., & Jin, J. (eds.) Brachiopods. Proceedings of the Third International Brachiopod Congress (pp. 29–33). Balkema.
Ciguel, J. H. G. y Peralta, S. H. (1990). Tentaculitoideos del Silúrico de la Precordillera de San Juan, República Argentina. XI Congreso Geológico Argentino, 2 (pp. 203–206). San Juan,
Cuerda, A. J. (1965). Monograptus leintwardinensis var. incipiens Wood en el Silúrico de la Precordillera. Ameghiniana, 4(5), 171–177.
Cuerda, A. J. (1969). Sobre las graptofaunas del Silúrico de San Juan, Argentina. Ameghiniana, 6(3), 223–235.
Cuerda, A. J. (1971). Monograpten des Under-Ludlow BUS der Vorkordillere von San Juan. Argentinien. Gio1ogisches Jarhuch, 85, 391–400.
Cuerda, A. J. (1974). Monograpten aus dem Ludlow Boliviens. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 6, 321–335.
Cuerda, A. J., Rickards, R. B. y Cingolani, C. (1988). A new Ordovician–Silurian boundary section in San Juan Province, Argentina, and its definite graptolite fauna. Journal of the Geological Society (London), 145, 745–757.
Gómez, M. J., Mestre, A., Corradini, C. y Heredia, S. (2021). A new species, Ozarkodina huenickeni, from the upper Silurian–Lower Devonian in San Juan Precordillera, South America. Journal of South American Earth Sciences, 108, 1–8.
Maletz, J. (1997). The rhabdosome structure of a Saetograptus species (Graptoloidea, Monograptacea) from a North German glacial boulder. Paläontologische Zeitschrift, 71(3), 247–255.
Maletz, J. (2014). The classification of the Pterobranchia (Cephalodiscida and Graptolithina). Bulletin of Geosciences, 89(3), 477–540.
Maletz, J., Soruco, R. S. y Egenhoff, S. O. (2002). Silurian (Wenlock–Ludlow) graptolites from Bolivia. Palaeontology, 45(2), 327–341.
Peralta, S. H. (1984a). Ludlowiano en la Precordillera Oriental sanjuanina. IX Congreso Geológico Argentino, 4 (pp. 296–304). Bariloche.
Peralta, S. H. (1984b). Nueva localidad con Monograptus argentinus Cuerda y Monograptus uncinatus notouncinatus Cuerda, en la Sierra de Talacasto, Precordillera de San Juan. IX Congreso Geológico Argentino, 4 (pp. 305–309). Bariloche.
Přibyl, A. (1942). Revision der Pristiograpten aus den Untergattungen Colonograptus n. subg. und Saetograptus n. subg. Mitteilungen der Tschechischen Akademie der Wissenschaften, 43, 161–184.
Ramos, V. A. y Vujovich, G. (2000). Hoja Geológica 3169-IV San Juan, provincia de San Juan. Servicio Geológico Minero Argentino.
Rickards, R. B., Brussa, E. D., Toro, B. A. y Ortega, G. (1996). Ordovician and Silurian graptolite assemblages from cerro del Fuerte, San Juan Province, Argentina. Geological Journal, 31, 101–122.
Rubinstein, C. V. (1992). Palinología del Silúrico Superior (Formación Los Espejos) en la quebrada de Las Aguaditas, Precordillera de San Juan, Argentina. Ameghiniana, 29(3), 231–248.
Whittingham, M., Spiridonov, A. y Radzevicius, S. (2021). Dynamic ecophenotypy in the Silurian Monograptidae (Graptolithina). Earth and Enviromental Science Transactions of the Royal Society of Edinburgh, Espontaneus Article. 1–10.
Additional Files
Published
Issue
Section
License
Copyright (c) 2022 Fernando Enrique Lopez
This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.
Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a CC Attribution-NonCommercial 4.0 that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
