Geologica Acta: an international earth science journal ISSN: 1695-6133 [email protected] Universitat de Barcelona España TABOADA, ARTURO CÉSAR; PAGANI, MARÍA ALEJANDRA The coupled occurrence of Cimmeriella-Jakutoproductus (Brachiopoda: Productidina) in Patagonia: implications for Early Permian high to middle paleolatitudinal correlations and paleoclimatic reconstruction Geologica Acta: an international earth science journal, vol. 8, núm. 4, diciembre, 2010, pp. 519-540 Universitat de Barcelona Barcelona, España Disponible en: http://www.redalyc.org/articulo.oa?id=50515686011 Cómo citar el artículo Número completo Sistema de Información Científica Más información del artículo Red de Revistas Científicas de América Latina, el Caribe, España y Portugal Página de la revista en redalyc.org Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto Geologica Acta, Vol.8, Nº 4, December 2010, 513-534 DOI: 10.1344/105.000001586 Available online at www.geologica-acta.com The coupled occurrence of Cimmeriella-Jakutoproductus (Brachiopoda: Productidina) in Patagonia: implications for Early Permian high to middle paleolatitudinal correlations and paleoclimatic reconstruction 1 2 ARTURO CÉSAR TABOADA and MARÍA ALEJANDRA PAGANI 1 CONICET-Laboratorio de Investigaciones en Evolución y Biodiversidad (LIEB), Facultad de Ciencias Naturales, Sede Esquel, Universidad Nacional de la Patagonia “San Juan Bosco” (UNPSJB) RN 259, km 16,5, Esquel (U9200), Chubut, Argentina. E-mail: [email protected] 2 CONICET-Museo Paleontológico “Egidio Feruglio” (MEF) Av. Fontana nº 140, Trelew (U9100GYO), Chubut, Argentina. E-mail: [email protected] ABSTRACT The brachiopod species Jakutoproductus sabattiniae sp. nov. and Cimmeriella willi sp. nov. from the Cisuralian deposits of the Tepuel-Genoa basin are described here. Biostratigraphy and stratigraphy of the uppermost section of the Tepuel Group (Mojón de Hierro and Río Genoa formations) are analyzed and a distinctive faunal succession is recognized: the Cimmeriella and Jakutoproductus faunal assemblages of late Sakmarian (Sterlitamakian) and early Artinskian estimated ages, respectively. The lower Permian correlations of these faunal occurrences and the chronology of mostly early Permian glacial episodes between Western and Eastern Argentina with Patagonia are discussed. The coupled Verchojania-Jakutoproductus, Eurydesma-Cimmeriella and Cimmeriella-Jakutoproductus faunal records have been used as a tool for the correlation of early Permian marine sequences from the high to middle paleolatidudinal settings of both hemispheres. KEYWORDS Cisuralian. Patagonia. Jakutoproductus. Cimmeriella. High paleolatitude correlations. INTRODUCTION of marine strata due to the predominance of continental facies (Río Genoa Formation). As a result, insufficient The marine upper Paleozoic of Patagonia has yielded information is presently available concerning the inver- representatives of most invertebrate groups: brachio- tebrate faunal diversity in the area. In order to obtain as pods, bivalves, gastropods, cephalopods, hyolithids, echi- much data as possible about the systematic composition noderms, cnidarians, ostracods and scarce trilobites, but and distribution of the biotic succession, it is necessary to warm-water fossil remains (foraminifers and conodonts) carry out more detailed research in the Río Genoa region are absent. The faunal succession of the type section of the to improve and complement the marine biostratigraphical Tepuel Group in the Tepuel-Genoa Basin is relatively well scheme of the Tepuel-Genoa Basin. Brachiopoda is one known (although not completely described), even though of the most abundant and highly diversified fossil group some southernmost localities have an incomplete sampling in the sedimentary column of the Tepuel-Genoa Basin. 519 A.C. TABOADA and M.A. PAGANI Cimmeriella and Jakutoproductus from the Early Permian of Patagonia Systematic and biostratigraphic works on this group have Paleozoic were determined by Suero (1953, 1958) and been made by several authors in the past fifty years (Amos, Ugarte (1966), and later formalized by Lesta and Ferel- 1958, 1960; Amos and Rolleri, 1965; González, 1985a; lo (1972) as the Río Genoa Group, including the Piedra Cúneo and Sabattini, 1987; Simanauskas, 1991, 1996a-c; Shotel and Nueva Lubecka formations. Afterward, an Simanauskas and Sabattini, 1993, 1997; Simanauskas and alternative interpretation was offered by Andreis et al. Archbold, 2002; Taboada, 1993, 2001a, 2008). The find- (1986), who downgraded the Río Genoa Group to for- ings here described have relevant paleobiogeographical mational rank and wholly correlated it with the median implications and have allowed conspicuous early Permian and upper parts of the Mojón de Hierro Formation, as biotic events in Patagonia to be identified. As a result, solid it was redefined by Page et al. (1984). Finally, Andreis correlation levels of intrabasinal, regional and interconti- and Cúneo (1989) recognized the uppermost strati- nental value, especially with median to high paleolatitude graphic beds as belonging also to a single and youngest faunas of both hemispheres are established. unit, the Río Genoa Formation, but conformably over- laying the Mojón de Hierro Formation at Lomas Chatas locality (the “Upper Tepuel System” in Ugarte, 1966). GEOLOGICAL AND STRATIGRAPHIC SETTING This last conception is here followed in a general way (Figure 2), nevertheless the precise boundary or a pos- In central-west Patagonia, the upper Paleozoic rocks sible lateral interfingering between the uppermost beds extend over vast areas between 43º- 44º 20’S and 69º 30’- of the Mojón de Hierro Formation and the lowermost 71ºW, and are distributed with north-northwest to south- strata of the Río Genoa Formation, is still in need of southeast trends. In the Chubut Province the neopaleozoic definition with accuracy. deposits belong to the foreland Tepuel-Genoa Basin, and outcrops are found in the Tepuel, Languiñeo, Tecka, Valle The material described in this contribution comes from Chico and Excursión hills, and the Río Genoa valley the Mojón de Hierro Formation, Tres Lagunas and La (Figure 1). The Tepuel-Genoa Basin outcrops show a Carlota Posts surrounding areas, and from the Río Genoa continuous sequence of more than 5000m thickness, ac- Formation, sampled at Cerro La Trampa and Piedra Shotel cumulated at the southwestern border of Gondwana during localities (Figure 1). Mississippian-Cisuralian times. In this sense, the Tepuel- Genoa basin is possibly the most complete open marine sequence of that age in all Gondwana. Early descriptions of the upper Paleozoic of central-west Patagonia were made by Keidel (1922) and Piatnitzky (1933, 1936). Suero (1948, 1953, 1958) recognized the late Paleozoic age of these deposits and outlined the stratigraphy of the basin. The upper Paleozoic column unconformably overlies the Catreleo Devonian granite (Robbiano 1971) and is overlain also uncomformably by Lower Jurassic marine strata. Its contact with the lower sections in the north of the basin when compared with the southern region, provides a north to south “rejuvena- tion” of the sequence. Other stratigraphic studies were later supplied by Perrot (1960), Freytes (1971), Lesta and Ferello (1972), Franchi and Page (1980) and Page et al. (1984). These last authors (Page et al. 1984) pro- posed the current mostly accepted stratigraphic scheme of the area north to 44ºS, with a tripartite succession of the Jaramillo, Pampa de Tepuel and Mojón de Hi- erro formations constituting the Tepuel Group, a major lithostratigraphic unit with its type section throughout the Tepuel hill. Other units were locally defined in the Languiñeo (Las Salinas Formation of González 1972) and Esquel areas (Esquel and Valle Chico formations of Cucchi 1980) and correlated with different sections of the Tepuel Group. In the area of the Río Genoa valley and south to 44ºS, the uppermost sections of the upper FIGURE 1 Location map showing fossiliferous localities. Geologica Acta, 8(4), 513-534 (2010) 520 DOI: 10.1344/105.000001586 A.C. TABOADA and M.A. PAGANI Cimmeriella and Jakutoproductus from the Early Permian of Patagonia Previous biostratigraphical and biochronologi- mation, probably the youngest faunal association and top cal proposals of the Costatumulus Zone of the Tepuel-Genoa Basin, con- sidered its age as Artinskian-Kungurian (Simanauskas and The first biozonation scheme proposed to the Tepuel- Sabattini, 1997; Hlebszevitch and Sabattini, 2005) and late Genoa basin was done by Amos and Rolleri (1965), who Sakmarian (Sterlitamakian) (Simanauskas and Archbold, recognized two biostratigraphic units based on brachio- 2002). Moreover, Pagani and Sabattini (2002) introduced pods described by Amos (1960): the Levipustula levis two new biozonations for the Tepuel-Genoa Basin, one of (Moscovian) and Cancrinella cf. farleyensis (late Carbon- them based exclusively on the distribution of gastropods iferous) biozones. These two units also extend 2000 km and bivalves: Mourlonia sp. II- Pyramus primigenius, Cal- to the north, reaching the Calingasta-Uspallata sub-basin litomaria tepuelensis-Streblochondria sp., and Euphemites in western Argentina (Precordillera) (Amos and Rolleri, chubutensis-Palaeoneilo aff. concentrica zones; and the 1965). Later, the ages of these biozones were adjusted by other based on cephalopods distribution: Sueroceras ir- Amos et al. (1973), Sabattini (1978) and González (1981, regulare and Mooreoceras zalazarensis