Fil: Giuliano, María Eugenia. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Ortega, Gladys del Carmen. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba; ArgentinaFil: Albanesi, Guillermo Luis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Ciencias de la Tierra; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba; ArgentinaFil: Monaldi, Cesar Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentin

Albanesi, Guillermo Luis

Giuliano, María Eugenia

Monaldi, Cesar Ruben

Ortega, Gladys del Carmen

LARI Creek, also named El Médano Creek, nearby the Salar del Rincón, is located in westernmost Salta Province, northwestern Argentina. It belongs to the Puna geological province, in the southern part of the Central Andean Basin (Moya et al., 1993). In this area, a succession of continental and marine Paleozoic rocks crop out. The lower sequence that bears significant index fossils is intruded by Ordovician volcanic rocks, and covered by clastic and pyroclastic deposits of Cenozoic age (Koukharsky, 1988; Moya et al., 1993; Koukharsky et al., 1996; Galli et al., 2010). This stratigraphic interval is particularly interesting because the index fossils reveal the transitional levels between the Cambrian and Ordovician systems and, therefore, the discussed position of the inter-systemic boundary in South America (Albanesi et al., 2010)...Fil: Giuliano, María Eugenia. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Ortega, Gladys del Carmen. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba; ArgentinaFil: Albanesi, Guillermo Luis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Ciencias de la Tierra; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba; ArgentinaFil: Monaldi, Cesar Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentin

LAReferencia - Red Federada de Repositorios Institucionales de Publicaciones Científicas Latinoamericanas

Publicación Especial Nº 13BUENOS AIRES2013ASOCIACIÓN PALEONTOLÓGICA ARGENTINACONODONTS FROM THE ANDESProceedings of the 3rd International Conodont Symposium&Regional Field Meeting of the IGCP project 591Edited byGuillermo L. Albanesi and Gladys Ortega33UPPER CAMBRIAN/LOWER ORDOVICIAN CONODONT AND GRAPTOLITE RECORDS IN THE LARI SECTION, SALAR DEL RINCÓN, PUNA OF SALTA, ARGENTINAGIULIANO, M. E.1,2, ORTEGA, G.1,3, ALBANESI, G. L.1,2,3 AND MONALDI, C. R. 41 Museo de Paleontología, CIGEA Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Casilla de Correo 1598, 5000 Córdoba,Argentina; gcortega@arnet.com.ar, galbanes@com.uncor.edu, megiuliano@efn.uncor.edu2 CICTERRA-CONICET, Córdoba, Argentina. 3 CONICET, FCEFyN, Universidad Nacional de Córdoba, Argentina.4 CONICET, Facultad de Ciencias Naturales, Universidad Nacional de Salta, Argentina; crmonaldi@arnet.com.arKeywords: Conodonts. Graptolites. Cambrian. Ordovician. Puna. Argentina.CONODONTS FROM THE ANDES - Publicación Especial Nº 13 - Julio 2013 - PALEONTOLOGICAL NOTELARI Creek, also named El Médano Creek, nearby the Salardel Rincón, is located in westernmost Salta Province, north-western Argentina. It belongs to the Puna geological province,in the southern part of the Central Andean Basin (Moya et al.,1993). In this area, a succession of continental and marine Pa-leozoic rocks crop out. The lower sequence that bears significantindex fossils is intruded by Ordovician volcanic rocks, and cov-ered by clastic and pyroclastic deposits of Cenozoic age(Koukharsky, 1988; Moya et al., 1993; Koukharsky et al., 1996;Galli et al., 2010). This stratigraphic interval is particularly in-teresting because the index fossils reveal the transitional levelsbetween the Cambrian and Ordovician systems and, therefore,the discussed position of the inter-systemic boundary in SouthAmerica (Albanesi et al., 2010).An invertebrate fauna composed of trilobites, sponges,graptolites, and microfossils (conodonts and palynomorphs)was recorded in the Las Vicuñas Formation of the upper Furon-gian/lower Tremadocian (Moya et al., 1993; Carrera, 1998; Raoet al., 2000; Vaccari et al., 2010; Toro et al., 2011).The conodonts and graptolites recorded in the upper partof the Las Vicuñas Formation, suggest a probable late Furon-gian age for the basal levels, and an early Tremadocian age forthe uppermost levels, although the assignment of a definite ageis still tentative. GEOLOGIC SETTING AND STRATIGRAPHYAn extensive Paleozoic succession covered by Cenozoic de-posits is exposed in the Lari creek (Upper Cambrian-Permian)(Fig. 1). The oldest unit referred to as Tremadocian is the LasVicuñas Formation (Moya et al., 1993), which is characterizedby clastic and pyroclastic rocks, calcarenites and coquinas cor-responding to platform environments (Moya et al., 1993;Koukharsky et al., 1996). The basal part of the formation iscovered by Quaternary debris, and the upper succession is in-truded by Ordovician quartzitic porphyries unconformablycovered by the Salar del Rincón Formation (Aceñolaza et al.,1972a y b), which preserves Hirnantian to Llandovery marinefaunas (Isaacson et al., 1976; Benedetto and Sánchez, 1990;Vaccari et al., 2010; Galli et al., 2010). The Cerro Oscuro Formation (Aceñolaza et al., 1972a, b)unconformably overlies the Salar del Rincón Formation. Its ageis assigned to the Late Carboniferous according to paleobotan-ical remains. Lower Permian rocks corresponding to the ArizaroFormation (Aceñolaza et al., 1972 a, b) paraconformably overliethe Cerro Oscuro Formation. The youngest units of the areaare described as tuffs and ignimbrites of the Tajamar Formation(Neogene), as well as Quaternary clastic deposits and volcanicrocks (Galli et al., 2010, and references therein). In Lari Creek, the Las Vicuñas Formation is ca. 220 m thick(Moya et al., 1993). The lower 5 m are composed of green-graysilty shales overlain by a succession of pyroclastic rocks andquartz sandstones, ca. 132 m thick. The unconformably over-lain upper part of the formation is made up of black shales thatare partly silicified, and fine sandstones, calcarenites, calcareousshales and coquinas. This upper part of the unit that bears theconodonts and graptolites studied herein, reaches ca. 124 mthick in the measured profile (Fig. 2). These shales are intrudedby a quartzitic porphyry in the uppermost strata of the LasVicuñas Formation.Coquinas, calcarenites and calcareous concretions are dis-tributed throughout the upper part of the formation; neverthe-less, only the two lower beds yielded conodonts. Rao et al.(2000) documented Cordylodus caboti Bagnoli, Barnes andStevens, C. intermedius Furnish, and Phakelodus tenuis (Müller)for the same strata. Additionally, our conodont collection in-cludes Cordylodus lindstromi Druce and Jones, C. proavusMüller, C. deflexus Bagnoli, Barnes and Stevens and Teridontusnakamurai (Nogami) (Fig. 3). The uppermost strata of the Las Vicuñas Formation bearan abundant and monotonous graptolite fauna composed ofRhabdinopora flabelliformis cf. f. parabola (Bulman) (Fig. 3).The first mention of this fauna was made by Rao et al. (2000),who reported the presence of Rhabdinopora sp. Recently,Vacarri et al. (2010) and Toro et al. (2011) cited R. f. parabolaCONODONTS FROM THE ANDES - Publicación Especial Nº 13 - Julio 2013 - PALEONTOLOGICAL NOTE34Figure 1. Location map of the study area and geology of Lari Creek, Salardel Rincón (modified from Galli et al., 2010). Figure 2. Stratigraphic column of the Las Vicuñas Formation at Lari Creek,with the ranges of the conodonts and graptolites and the correspondingbiozonation (Cn.: conodont zone; Gr.: graptolite zone; R. f. parabola: Rhab-dinopora flabelliformis parabola. Black stars represent the species recordsby Rao et al., (2000).few meters above the trilobite Jujuyaspis keideli Kobayashi, inthe same succession. Other records of trilobites (Kainella sp.,Asaphellus aff. comunis Robison and Pantoja-Alor, Onichopygesp.) in this formation are mentioned in Moya et al. (1993). Car-rera (1998) described the hexactinellid sponge Larispongia mag-dalenae n. sp., recorded in the upper Las Vicuñas Formation. The Tremadocian succession of Lari Creek was folded andfaulted during the Ocloyic Phase, as evidenced by the angularunconformity between the Las Vicuñas Formation and the Hir-nantian/Llandovery strata of the Salar del Rincón Formation(Donato and Vergani, 1985; Moya et al., 1993). Other tectonicevents were dated as Carboniferous and Cenozoic, related toAndean tectonics (Moya et al., 1993). The studied section cor-responds to a faulted syncline with minor folds in the hinge. BIOSTRATIGRAPHYConodontsAll of the conodont species recorded in the studied sectionspan the Cambrian/Ordovician boundary; although, the con-odont association documented is characteristic of the Cordylo-dus lindstromi Zone. It is scarcely represented in coquinas andcalcarenites of the basal upper part of the Las Vicuñas Forma-tion, in the samples SR1 and SR2 (Fig. 2). The conodontrecord includes Cordylodus lindstromi Druce and Jones, C.proavus Müller, C.deflexus Bagnoli, Barnes and Stevens, andTeridontus nakamurai (Nogami) (Fig. 3). The Cordylodus lindstromi Zone was defined in westernNorth America by Miller (1988), and Barnes (1988) recognizedit in western Newfoundland. The records of C. lindstromi inUtah, Texas and Oklahoma correspond to the C. lindstromi andIapetognathus zones according to Nicoll et al. (1999). This bio-zone is represented worldwide with records in Australia,Canada, China, Iran, and Kazajstan (Cooper et al., 2001). Innorthwestern Argentina, the Cordylodus lindstromi Zone wasdetermined in the Cajas range, Tilcara range, and the Parchaarea from Cordillera Oriental and the Salar del Rincón fromthe Puna of Salta province (Rao, 1999; Tortello et al., 1999;Pacheco, 2009; Zeballo et al., 2011, among others), and in theVolcancito Formation, Famatina System (Albanesi et al., 1999,2005). The base of the C. lindstromi Zone was informally consid-ered as the base of the Ordovician System (Barnes, 1988). Later,Cooper et al. (2001) recognized the conodont Iapetognathusfluctivagus Nicoll et al. as marker of the Cambrian/Ordovicianboundary, including the C. lindstromi Zone in the Furongian(Stage 10). When I. fluctivagus is absent, C. lindstromi can beconsidered as an approximation of this systemic boundary. Reassessing the GSSP of Green Point, Terfelt et al. (2012)observed that the specimens of I. fluctivagus illustrated byCooper et al. (2001) would correspond to I. preaengensis Land-ing, which appears in the Cordylodus intermedius Zone (Hir-sutodontus simplex Subzone) of late Cambrian age. Thereby, ifthe revision of Terfelt et al. (2012) were verified, the C. lind-stromi Zone would be reestablished in the Tremadocian Stage.GraptolitesBlack shales from the upper Las Vicuñas Formation bearspecimens of Rhabdinopora (Fig. 3), which are abundant insome levels. It is a monotonous graptolite fauna composed ofsiculae, proximal ends, and juvenile and mature rhabdosomes,usually incomplete and poorly preserved. Quadriradiate prox-imal development is observed in growth stages preserved in dis-coidal view. The rhabdosome outline form is variable, rangingfrom broad to narrow cone shape. The sicula is 1 mm in length.The stipes are sinous, spaced from 11 to 12.5 in 10 mm in thedistal part of the rhabdosomes, but in some specimens thisnumber can be 13 to 13.5. In the proximal part of some rhab-dosomes it is possible to measure 9 stipes in 10 mm, but thisspacing tends to be variable. Thecae, rarely preserved, are spacedin number of approximately 14 in 10 mm. Dissepiments arethin, normal to inclined to the stipes, and irregularly spacedthroughout the mesh, counting more than 17 in 10 mm, insome specimens. This material resembles R. flabelliformisparabola in the presence of an irregular meshwork, with sinuousstipes. However, the stipes are closer spaced than in this sub-species (8-11 stipes in 10 mm), a character that does not allowsafe taxonomic identification. The graptolite material studied in the upper part of the LasVicuñas Formation can tentatively be referred to the Rhabdino-pora flabelliformis parabola Zone, the second graptolite zone ofthe Tremadocian Stage (Cooper et al., 1998), until new infor-mation about this fauna is obtained.ACKNOWLEDGEMENTSThis study has been supported by FONCyT PICT 1797,CONICET, and Universidad Nacional de Córdoba, Argentina,and is part of the doctoral thesis project of M. E. Giuliano. Thispaper is a contribution to the IGCP project 591.GIULIANO ET AL.: THE CAMBRO-ORDOVICIAN BOUNDARY IN PUNA OCCIDENTAL, ARGENTINA.35CONODONTS FROM THE ANDES - Publicación Especial Nº 13 - Julio 2013 - PALEONTOLOGICAL NOTE36Figure 3. Upper Cambrian/Lower Ordovician conodonts (Cordylodus lindstromi Zone) and Lower Ordovician graptolites (Rhabdinopora flabelliformisparabola Zone) from Lari Creek, Puna Occidental, Salta Province, Argentina. 1-4, Teridontus nakamurai (Nogami), 1, Sb element, 2-3, Sd element (CORD-MP 28403/1-24), 4, Sc-Sb? element (CORD-MP 28048/1). 5-7, Cordylodus lindstromi Druce and Jones, M elements, 5-7, (CORD-MP 28406/1-3). 8, Cordy-lodus deflexus Bagnoli, Barnes and Stevens, compressed element S (CORD-MP 28405/1). 9-12, Cordylodus proavus Müller, 9,11, (CORD-MP 28401/1-13),12, (CORD-MP 28407/1). Scale bar: 0.1 mm. 13-16, Rhabdinopora flabelliformis cf.  f. parabola, 13, Proximal part of mature colony with parabolic form(CORD-PZ 33057), 14, detail of meshwork showing dissepiments and stipe dendroid structure (CORD-PZ 33055-b 1), 15, proximal end (CORD-PZ 33055-b 2), 16, mature rhabdosome (CORD-PZ 33061-b). Scale bar: 1 mm. REFERENCESAceñolaza, F.G., Benedetto, J.L., Koukharsky, M., Salfity, J.A. and Viera, O.1972a. Presencia de sedimentitas devónicas y neopaleozoicas en la Puna deAtacama, provincia de Salta, Argentina. Asociación Geológica Argentina 27(3): 345-346. Notas breves. Aceñolaza, F.G., Benedetto, J.L. and Salfity, J.A. 1972b. El Neopaleozoico dela Puna Argentina: Su fauna y relación con áreas vecinas. Academia Brasileirade Ciencias, Anales 44 (Suplemento): 5-20.Albanesi, G.L., Esteban, S.B. and Barnes, C.R. 1999. Conodontes del intervalodel límite Cámbrico-Ordovícico en la Formación Volcancito, Sistema deFamatina, Argentina. Temas Geológico-Mineros ITGE 26: 521-526Albanesi, G.L., Esteban, S.B., Ortega, G. Hünicken, M.A. and Barnes, C.R.2005. Bioestratigrafía y ambientes sedimentarios de las Formaciones Vol-cancito y Bordo Atrasado (Cámbrico Superior-Ordovícico Inferior), Sistemade Famatina, provincia de La Rioja. Asociación Geológica Argentina, SerieD: Publicación Especial 8: 41-64.Albanesi, G.L., Ortega, G., Zeballo, F.J. and Pacheco, F.E. 2010. The Cam-brian-Ordovician boundary in South America: High resolution biostratig-raphy, global correlation and paleoenvironments. 3th InternationalPalaeontological Congress (London): 67.Barnes, C.R. 1988. The proposed Cambrian-Ordovician global boundary stra-totype and point (GSSP) in Western Newfoundland, Canada. GeologicalMagazine 125 (4): 381-414.Benedetto, J.L. and Sánchez, T.M. 1990. Fauna y edad del estratotipo de laFormación Salar del Rincón (Eopaleozoico, Puna, Argentina). Ameghiniana27 (3-4): 317-326. Carrera, M.G. 1998. First Ordovician sponge from the Puna región, North-western Argentina. Ameghiniana 35 (2): 205-210. Cooper, R.A., Nowlan, G.S. and Williams, S.H. 2001. Global stratotype sec-tion and point for the base of the Ordovician System. Episodes 24 (1): 19-28.Donato, E.O. and Vergani, G. 1985. Geología del Devónico y Neopaleozoicode la zona del cerro Rincón, provincia de Salta, Argentina. IV Congreso Ge-ológico Chileno, Actas I: 268-283. Galli, C.I., Moya M.C. and Arnosio, M. 2010. Estudios sedimentológicos enlos depósitos carboníferos y pérmicos del borde occidental de la Puna. Re-vista de la Asociación Geológica Argentina 66(1): 119-132. Isaacson, P.E., Antelo, B. and Boucot, A.J. 1976. Implications of a Llandovery(Early Silurian) brachiopod fauna from Salta Province, Argentina. Journalof Paleontology 50 (6): 1103-1112.Koukharsky, M.M.L. 1988. El volcanismo ácido ordovícico y las rocas graníti-cas de la Puna occidental entre las latitudes 24º y 24º20´S. Revista de laAsociación Geológica Argentina 43: 253-256. Koukharsky, M., Torres Claro, R., Etcheverría, M., Vaccari, N.E. and Waisfeld,B.G. 1996. Episodios volcánicos del Tremadociano y del Arenigiano enVega Pinato, Puna salteña, Argentina. XIII Congreso Geológico Argentino yIII Congreso de Exploración de Hidrocarburos, Actas V: 535-542. Miller, J.F. 1988. Conodonts as biostratigraphic tools for redefinition and cor-relation of the Cambrian-Ordovician boundary. Geological Magazine 125:349-362.Moya, M.C., Malanca, S., Hongn, F.D. and Bahlburg, H. 1993. El Tremadoctemprano en la Puna Occidental Argentina. XII Congreso Geológico Ar-gentino y II Congreso de Exploración de Hidrocarburos, Actas II: 20-30. Nicoll, R.S., Miller, J.F., Nowlan, G.S., Repetski, J.E. and Ethington, R.L.1999. Iapetonudus (n. gen.) and Iapetognathus Landing, unusual EarliestOrdovician multielement conodont taxa and their utility for biostratigra-phy. Brigham Young University Geology Studies 44: 27-101. Pacheco, F.E. 2009. [Bioestratigrafía de conodontes y paleoambientes de la For-mación Cardonal en la Sierra de Cajas, Cordillera Oriental, noroeste de Ar-gentina. Universidad Nacional de Córdoba. Facultad de Ciencias ExactasFísicas y Naturales, Córdoba. Tesis de Licenciatura, 116 pp. Inédito.]. Rao, R.I. 1999. Los conodontes cambro-ordovícicos de la sierra de Cajas y delEspinazo del Diablo, Cordillera Oriental, República Argentina. Revista Es-pañola de Micropaleontología 31: 5-20.Rao, R.I., Moya, M.C. and Hünicken, M.A. 2000. Conodontes en la Forma-ción Las Vicuñas (Tremadoc temprano), Puna occidental argentina. Amegh-iniana 37 (4) Suplemento:13R. Terfelt, F, Bagnoli, G. and Stouge, S. 2012. Re-evaluation of the conodont Ia-petognathus and implications for the base of the Ordovician System GSSP.Lethaia 45 (2): 227-237.Toro, B.A., Vaccari, N.E., Vento, B.A. and Balseiro, D. 2011. Implicacionesbioestratigráficas del estudio de las subespecies de graptolitos Rhabdinoporaflabelliformis (Tremadociano) de la Cuenca Andina Central de Argentina yBolivia. Ameghiniana 48 (4) Suplemento: R26. Tortello, M.F., Rábano, I., Rao, R. and Aceñolaza, F.G. 1999. Los trilobitesde la transición Cámbrico-Ordovícico en la quebrada Amarilla (Sierra deCajas, Jujuy, Argentina). Boletín Geológico y Minero 110 (5): 555-572.Vaccari, N.E., Toro, B.A., de la Puente, S.G. and Rubinstein, C.V. 2010.Nuevos aportes al conocimiento del Paleozoico inferior del área de Salar delRincón, Puna occidental, Argentina. X Congreso Argentino de Paleontologíay Bioestratigrafía. VII Congreso Latinoamericano de Paleontología (La Plata)Resúmenes: 56.Zeballo, F.J., Albanesi, G.L. and Ortega, G. 2011. Biostratigraphy and pale-oenvironments of the Santa Rosita Formation (Late Furongian-Tremado-cian), Cordillera Oriental of Jujuy, Argentina. In Gutiérrez- Marco, J.C,Rábano, I.  and García-Bellido, D. (Eds.), Ordovician of the World.Cuadernos del Museo Geominero 14: 625-632. GIULIANO ET AL.: THE CAMBRO-ORDOVICIAN BOUNDARY IN PUNA OCCIDENTAL, ARGENTINA.37

English

Upper Cambrian/Lower Ordovician conodont and graptolite records in the Lari section, Salar del Rincón, Puna of Salta, Argentina

CONICET Digital

http://ri.conicet.gov.ar/bitstream/handle/11336/3128/Giuliano_et_al_.pdf?sequence=1&isAllowed=y

Upper Cambrian/Lower Ordovician conodont and graptolite records in the Lari section, Salar del Rincón, Puna of Salta, Argentina

Abstract

Similar works

Full text

Available Versions

LAReferencia - Red Federada de Repositorios Institucionales de Publicaciones Científicas Latinoamericanas

CONICET Digital