Sr, C and O isotope composition of marbles from the Sierra de de Ancasti, Eastern Sierras Pampeanas, Argentina: age and constraints for the Neoproterozoic–Lower Paleozoic evolution of the proto-Gondwana margin


  • J.A. MURRA
  • E.G. BALDO



Isotope stratigraphy, Neoproterozoic, Gondwana, Ancasti, Sierras Pampeanas


The Sierra Brava Complex on the eastern flank of the Sierra de Ancasti consists of marbles, metabasites, calc-silicate rocks, psammo-pelitic schists and gneisses. In the central part of this sierra a thick succession of banded schists (Ancasti Formation) crops out. Regional metamorphism of these rocks is attributed to the Famatinian orogeny (Ordovician), metamorphic grade increasing westwards and southwards and culminating in a migmatite complex on the western side of the Sierra. The meta-carbonate rocks are subdivided into a northeastern group (low-grade calcite marbles), and a southeastern group (high-grade calcite and calcite-dolomite marbles). Twenty-three marble samples were analysed for Sr isotope composition and Rb, Mn, Mg and Ca contents, and six for C and O isotope composition. An Ediacaran depositional age of 570 –590Ma is inferred by reference to the trend of 87Sr/86Sr in Neoproterozoic seawater. Thus the metacarbonates are probably slightly older than the Ancasti Formation (equivalent to the Puncoviscana Formation of northern Argentina), which has a maximum sedimentation age of ca. 570Ma. Ediacaran depositional ages have also been reported for metacarbonates elsewhere in Argentina, Uruguay and Brazil. We propose that the Sierra de Ancasti carbonates on one hand, and those in the Western Sierras Pampeanas (Difunta Correa Sequence) and –tentativelythe Corumbá Group of Brazil on the other, represent platforms on opposite margins of the extinct Clymene Ocean, whereas Neoproterozoic carbonate successions such as the Loma Negra Formation (Tandilia, southern Argentina) and the Arroyo del Soldado Group (Uruguay) were deposited on the eastern side (present coordinates) of the Rio de la Plata craton, which at the time occupied a position farther to the north.


Aceñolaza, F., Toselli, A., 1981. Geología del Noroeste Argentino. Publicación de la Facultad de Ciencias e Instituto Miguel Lillo, Tucumán, Universidad Nacional de Tucumán, 212pp.

Aceñolaza, F., Miller, H., Toselli, A., 1983. Geología de la Sierra de Ancasti. Münstersche Forschungen zur Geologie und Paläontologie, 59, 1-372.

Adams, C.J., Miller, H., Toselli, A.J., Griffin, W., 2008. The Puncoviscana Formation of northwest Argentina: U–Pb geochronology of detrital zircons and Rb–Sr metamorphic ages and their bearing on its stratigraphic age, sediment provenance and tectonic setting. Neues Jahrbuch fur Geologie und Pälaontologie, Abhandlungen, 247, 341-352.

Asmerom, Y., Jacobsen, S., Knoll., A., Butterfield, N., Swett, K., 1991. Strontium isotope variations of Neoproterozoic seawater: implications for crustal evolution. Geochimica et Cosmochimica Acta, 55, 2883-2894.

Baldo, E., Casquet, C., Colombo, F., Pankhurst, R., Galindo, C., Rapela, C., Dahlquist, J., Fanning, M., 2008. Magmatismo anorogénico Neoproterozoico (845 Ma) en las Sierras Pampeanas Occidentales de Maz y Espinal. ¿Nueva evidencia de rifting temprano de Rodinia? San Salvador de Jujuy, XVII Congreso Geológico Argentino, Actas, 1, 181-182.

Brand, U., Veizer, J., 1980. Chemical diagenesis of multicomponent carbonate system-1. Trace elements. Journal of Sedimentary Petrology, 50, 1219-1250.

Brasier, M., Shields, G., 2000. Neoproterozoic chemostratigraphy and correlation of the port askaig glaciation, dalradian supergroup of Scotland. Journal of the Geological Society, 157, 909-914.

Casquet, C., Baldo, E., Pankhurst, R., Rapela, C., Galindo, C., Fanning, C., Saavedra, J., 2001. Involvement of the Argentine Precordillera terrane in the Famatinian mobile belt: U-Pb SHRIMP and metamorphic evidence from the Sierra de Pie de Palo. Geology, 29(8), 703-706.

Casquet, C., Rapela, C., Pankhurst, R., Galindo, C., Dahlquist, J., Baldo, E., Saavedra, J., Gonzalez Casado, J., Fanning, M., 2004. Grenvillian massif-type anorthosites in the Sierras Pampeanas (Argentina). Journal of Geological Society of London, 162, 9-12.

Casquet, C., Pankhurst, R., Rapela, C., Galindo, C., Fanning, C., Chiaradia, M., Baldo, E., González-Casado, J., Dahlquist, J., 2008a. The Maz terrane: a Mesoproterozoic domain in the Western Sierras Pampeanas (Argentina) equivalent to the Arequipa-Antofalla block of southern Peru? Implications for Western Gondwana margin evolution. Gondwana Research, 13, 163-175.

Casquet, C., Pankhurst, R., Galindo, C., Rapela, C., Fanning, C., Baldo, E., Dahlquist, J.A., González-Casado, J.M., Colombo, F., 2008b. A deformed alkaline igneous rock – carbonatite complex from the Western Sierras Pampeanas, Argentina: evidence for late Neoproterozoic opening of the Clymene Ocean? Precambrian Research, 165, 205-220.

Cordani, U., Sato, K., Teixeira, W., Tassinari, C., Basei, M., 2000. Crustal evolution of the South American platform. In: Cordani, U., Miliani, E., Thomaz-Filho, A., Campos, D. (eds.). Tectonic evolution of South America. Rio de Janeiro (Brazil), 31º International Geological Congress, 19-40.

Cordani, U., Teixeira, W., D’Agrella-Filho, M., Trindade, R., 2009. The position of the Amazonian Craton in supercontinents. Gondwana Research, 15, 396-407.

Craig, H., 1957. Isotopic standards for carbon and oxygen and correction factors for mass spectrometric analysis of carbon dioxide. Geochimica Cosmochimica Acta, 12, 133-149.

Colombo, F., Baldo, E., Casquet, C., Pankhurst, R., Galindo, C., Rapela, C., Dahlquist, J., Fanning, M., 2009. A-type magmatism in the sierras of Maz and Espinal: a new record of Rodinia break-up in the western Sierras Pampeanas of Argentina. Precambrian Research, 175, 77-86.

Dahlquist, J., Pankhurst, R., Rapela, C., Galindo, C, Alasino, P., Fanning, C., Saavedra, J., Baldo, E., 2008. New SHRIMP U-Pb data from the Famatina Complex: Constraining earlymid Ordovician Famatinian Magmatism in the Sierras Pampeanas, Argentina. Geologica Acta, 6(4), 319-333.

Do Campo, M., Ribeiro Guevara, S., 2005. Provenance analysis and tectonic setting of Late Neoproterozoic metasedimentary successions in NW Argentina. Journal of South American Earth Sciences, 19, 143-153.

Fairchild, I., Marshall, J., Bertrand-Sarafati, J., 1990. Stratigraphic shifts in carbon isotopes from Proterozoic stromatolitic carbonates (Mauritania): influences of primary mineralogy and diagenesis. American Journal of Science, 290(A), 46-79.

Fuenlabrada, J.M., Galindo, C., 2001. Comportamiento de la relación 87Sr/86Sr en disoluciones de carbonatos impuros en función de la concentración ácida y en disoluciones de sulfatos en función del tiempo. Actas III Congreso Ibérico de Geología, 591-595.

Galindo, C., Casquet, C., Rapela, C., Pankhurst, R., Baldo, E., Saavedra, J., 2004. Sr, C and O isotope geochemistry and stratigraphy of Precambrian and lower Paleozoic carbonate sequences from the Western Sierras Pampeanas of Argentina: tectonic implications. Precambrian Research, 131(1-2), 55-71.

Hoefs, J., 1997. Stable Isotope Geochemistry. Berlin, SpringerVerlag, 201pp.

Jacobsen, S., Kaufman, A., 1999. The Sr, C and O isotopic evolution of Neoproterozoic seawater. Chemical Geology, 161, 37-57.

Jiang, G., Kaufman, A., Christie-Blick, N., Zhang, S., Wu, H., 2007. Carbon isotope variability across the Ediacarian Yangtze platform in South China: Implications for a large surface-to-deep ocean δ13C gradient. Earth and Planetary Science Letters, 261, 303-320.

Knüver, M., Miller, H., 1981. Ages of metamorphic and deformational events in the Sierra de Ancasti (Pampean Ranges; Argentina). Geologische Rundschan, 70, 1020-1042.

Knüver, M., Reissinger, M., 1981.The plutonic and metamorphic history of the sierra de Ancasti (Catamarca province, Argentina) ZBL. Geologisch und Paläontologie, 1(3/4), 285-297.

McCrea, J.M., 1950. On the isotope chemistry of carbonates and a paleotemperature scale. Journal de Chimie Physique, 18, 849-857.

Melezhik, V., Gorokhov, I., Fallick, A., Gjelle, S., 2001. Strontium and carbon isotope geochemistry applied to dating of carbonate sedimentation: an example from high-grade rocks of the Norwegian Caledonides. Precambrian Research, 108, 267-292.

Misi, A., Kaufman, A.J., Veizer, J., Powis, K., Azmy, K., Boggiani, P.C., Gaucher, C., Teixeira, J.B.G., Sanches, A.L., Iyer, S.S.S., 2007. Chemostratigraphic correlation of Neoproterozoic sucessions in South America. Chemical Geology, 237, 143-167.

Montañez, I., Osleger, D., Banner, J., Mack, L., Musgrove, M., 2000. Evolution of the Sr and C isotope composition of Cambrian oceans. Geological Society of America Today, 10(5), 1-5.

Murra, J., Baldo, E., 2006. Evolución tectonotermal ordovícica del borde occidental del arco magmático Famatiniano: metamorfismo de las rocas máficas y ultramáficas de la Sierra de la Huerta – Las Imanas (Sierras Pampeanas, Argentina). Revista Geológica de Chile, 33(2), 277-298.

Omarini, R., Sureda, R., Götze, H., Seilacher, A., Pflüger, F., 1999. Puncoviscana folded belt in northwestern Argentina: testimony of Late Proterozoic Rodinia fragmentation and pre-Gondwana collisional episodes. International Journal of Earth Sciences, 88, 76-97.

Prokoph, A., Shields, G., Veizer, J., 2008. Compilation and timeseries analysis of a marine carbonate δ18O, δ13C, 87Sr/86Sr and δ34S database through Earth history. Earth-Science Reviews, 87, 113-133.

Rapela, C., Pankhurst, R., Casquet, C., Baldo, E., Saavedra, J., Galindo, C., 1998. Early evolution of the Proto-Andean margin of South America. Geology, 26(8), 707-710.

Rapela, C., Fanning, M., Baldo, E., Dahlquist, J., Pankhurst, R., Murra, J., 2005. Coeval S- and I-type granites in the Sierra de Ancasti, Eastern Sierras Pampeanas, Argentina. Gondwana, 12, 307.

Rapela, C., Pankhurst, R., Casquet, C., Fanning, C., Baldo, E., González-Casado, J., Galindo, C., Dahlquist, J., 2007. The Río de la Plata craton and the assembly of SW Gondwana. Earth Science Reviews, 83, 49-82.

Schwartz, J., Gromet, L., 2004. Provenance of a late Proterozoicearly Cambrian basin, Sierras de Cordoba, Argentina. Precambrian Research, 129(1), 1-21.

Schwartz, J., Gromet, L., Miró, R., 2008. Timing and duration of the calc-alkaline arc of the Pampean Orogeny: implications for the Late Neoproterozoic to Cambrian evolution of Western Gondwana. The Journal of Geology, 116, 39-61.

Sial, A.N., Ferreira, V.P., Aceñolaza, F.G., Pimentel, M.M., Parada, M.A., Alonso, R.N., 2001. C and Sr isotopic evolution of carbonate sequences in NW Argentina: implications for probable Precambrian-Cambrian transition. Carbonates and Evaporites, 16, 141-152.

Siivola, J, Schmid, R., 2007. A systematic nomenclature for metamorphic rocks: 12. List of mineral abbreviations. Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks. Recommendations, web version of 01.02.2007, website:

Sims, J, Ireland, T., Camacho, A., Lyons, P., Pieters, P., Skirrow, R., Stuart-Smith, P., Miró, R., 1998. U-Pb, Th-Pb and ArAr geochronology from the southern Sierras Pampeanas, Argentina: implications for the Paleozoic tectonic evolution of the western Gondwana margin. In: Pankhurst, R., Rapela, C. (eds). The proto-Andean Margin of Gondwana. Geological Society of London, 142 (Special Publication), 259-282.

Toselli, A., Aceñolaza, F., Sial, A., Rossi, J., Ferreira, V., Alonso, R., Parada, M., Gaucher, C., 2005. Los carbonatos de la Formacion Puncoviscana s.l.: correlacion quimioestratigrafica e interpretación geológica. La Plata, 10º Congresso Brasileiro de Geoquímica, 2 (Actas), 327-333.

Trindade, R., D’Agrella-Filho, M., Epof, I., Brito Neves, B., 2006. Paleomagnetism of Early Cambrian Itabaiana mafic dikes (NE Brazil) and the final assembly of Gondwana. Earth and Planetary Science Letters, 244, 361-377.

Varela, R., Valencio, S., Ramos, A., Sato, K., González, P., Panarello, H., Roverano, D., 2001. Isotopic strontium, carbon and oxygen study on Neoproterozoic marbles from Sierra de Umango, and their foreland, Argentina. Santiago (Chile), III South American Symposium on Isotope Geology, 450-453.

Veizer, J., Ala, D., Azmy, K., Bruckschen, P., Buhl, D., Bruhn, F., Carden, G.A.F., Diener, A., Ebneth, S., Goddéris, Y., Jasper, T., Korte, C., Pawellek, F., Podlaha, O.G., Strauss, H., 1999. 87Sr/86Sr, 13C and 18O evolution of Phanerozoic seawater. Chemical Geology, 161, 59-88.

Vujovich, G., van Staal, C., Davis, W., 2004. Age constraints on the tectonic evolution and provenance of the Pie de Palo Complex, Cuyania Composite Terrane, and the Famatinian Orogeny in the Sierra de Pie de Palo, San Juan, Argentina. Gondwana Research, 7(4), 1041-1056.

Willner, A., 1983. Evolución metamórfica. In: Aceñolaza, G., Miller, H., Toselli, A. (eds.). Geología de la sierra de Ancasti. Münster Forschungen zur Geologie und Palaentologie, 59, 189-200.

Zimmermann, U., 2005. Provenance studies of very lowto lowgrade metasedimentary rocks of the Puncoviscana complex, northwest Argentina. In: Vaughan, A., Leat, P., Pankhurst, R. (eds.). Terrane processes at the margin of Gondwana. Geological Society of London, 246 (Special Publication), 381-416.