Microstructural and geochemical analysis of Paleoproterozoic pseudotachylytes in Río de la Plata craton, Tandilia belt, Argentina

Authors

  • M.C. FRISICALE INGEOSUR-CONICET-Departamento de geología. Universidad Nacional del Sur. San Juan 670. B8000ICN Bahía Blanca, Argentina. Fax: +54 291 4595148
  • L.V. DIMIERI INGEOSUR-CONICET-Departamento de geología. Universidad Nacional del Sur. San Juan 670. B8000ICN Bahía Blanca, Argentina.
  • J.A. DRISTAS INGEOSUR-CONICET-Departamento de geología. Universidad Nacional del Sur. San Juan 670. B8000ICN Bahía Blanca, Argentina.
  • V. ARAUJO INGEOSUR-CONICET-Departamento de geología. Universidad Nacional del Sur. San Juan 670. B8000ICN Bahía Blanca, Argentina.
  • N. FORTUNATTI INGEOSUR-CONICET-Departamento de geología. Universidad Nacional del Sur. San Juan 670. B8000ICN Bahía Blanca, Argentina.

DOI:

https://doi.org/10.1344/105.000001744

Keywords:

Pseudotachylyte, Paleoproterozoic, Río de la Plata craton, Mylonite

Abstract

The current study focuses on the analysis of pseudotachylytes from the Azul Megashear Zone, located in the Río de la Plata craton, central Argentina. This shear zone is a strip of mylonitic rocks of more than 40km in length and with a maximum width of 2.5km. Glassy and microcrystalline pseudotachylytes are hosted by Paleoproterozoic gneiss mylonite, granitoid mylonite, granulite mylonite and striped gneisses. The pseudotachylytes occur as fault and injection veins characterized by sharp contacts with no gradation into the mylonites and show meltorigin features such as partially melted quartz and feldspar clasts with embayed rims and flow structures. Their composition is similar to that of the rocks in which they are injected. In those cases involving banded host rocks, slight chemical differences can be observed in the pseudotachylytes mainly in terms of their fabric and mineralogy. Most pseudotachylytes have textures deriving from post-solidification ductile deformation, but others bearing mylonite-like features are related to viscous flow prior to complete solidification. There are indications that some of these pseudotachylytes were formed during the ductile regime, others being generated in the brittle regime during shear zone reactivation following exhumation or uplift. The occurrence of several pseudotachylytegenerating events indicates intermittent aseismic/seismic slip at different crustal levels throughout this shear zone.

References

Barker, S.L., 2005. Pseudotachylyte-generating faults in Central Otago, New Zealand. Tectonophysics, 397, 211-223.

Boullier, A.M., Bouchez, J.L., 1978. Le quartz en rubans dans les mylonites. Bulletin of the Geological Society France, 20, 253-262.

Brodie, K., 1998. High-temperature mylonites: I. Metabasic mylonites. In: Snoke, A., Tullis, J., Todd, V. (eds.). Faultrelated rocks. A Photographic Atlas. Princeton, Princeton University Press, 428-435.

Caggianelli, A., de Lorenzo, S., Prosser, G., 2005. Modelling the heat pulses generated on a fault plane during coseismic slip: Interferences from the pseudotachylytes of the Copanello cliffs (Calabria, Italy). Tectonophysics, 405, 99-119.

Camacho, A., Vernon, R.H., FitzGerald, J.D., 1995. Large volumes of anhydrous pseudotachylyte in the Woodroffe Thrust, eastern Musgrave Ranges, Australia. Journal of Structural Geology, 17(3), 371-383.

Chen, G.N., Grapes, R., 2007. Granite genesis: In-situ melting and crustal evolution. Dordrecht (The Netherlands), Springer, 277pp.

Cingolani, C.A., 2010. The Tandilia System of Argentina as a southern extension of the Río de la Plata craton: an overview. International Journal of Earth Sciences, 100(2-3), 221-242.

Cingolani, C.A., Dalla Salda, L.H., 2000. Buenos Aires cratonic region. In: Cordani, U., Milani, E., Thomaz Filho, A., Campos, D. (eds.). Tectonic evolution of South America, Rio de Janeiro, Brazil, 139-146.

Coelho, J., 2005. GEOISO-A WindowsTM program to calculate and plot mass balances and volume changes occurring in a wide variety of geologic processes. Computers & Geosciences, 32, 1523-1528.

Coutinho, J., Kräutner, H., Sassi, F., Schmid, R., Sen S., 2007. Amphibolite and Granulite. In: Fettes, D., Desmons, J. (eds). Metamorphic Rocks. A Classification and Glossary of Terms. Cambridge, Cambridge University Press, 244pp.

Dalla Salda, L., 1981. Tandilia, un ejemplo de tectónica de transcurrencia en basamento. Revista de la Asociación Geológica Argentina, 43(2), 198-209.

Dalla Salda, L., Bossi, J., Cingolani, C., 1988. The Río de la Plata cratonic region of southwestern Gondwanaland. Episodes, 11(4), 263-269.

Di Toro, G., Pennacchioni, G., 2004. Superheated frictioninduced melts in zoned pseudotachylytes within the Adamello tonalites (Italian Southern Alps). Journal of Structural Geology, 26(10), 1783-1801.

Di Toro, G., Pennacchioni, G., Nielsen, S., 2009. Pseudotachylytes and earthquake source mechanics. In: Fukuyama, E. (ed.).

Fault-Zone Properties and Earthquake Rupture Dynamics. Elsevier Academic Press, 87-133.

Fabbri, O., Lin, A., Tokushige, H., 2000. Coeval formation of cataclasite and pseudotachylyte in a Miocene forearc granodiorite, southern Kyushu, Japan. Journal of Structural Geology, 22, 1015-1025.

Frisicale, M.C., Dimieri, L.V., Dristas, J.A., 1998. The Boca de la Sierra megashear zone, Tandilia, Argentina. Terra Nostra. Bayreuth, 16 Geowissenschaftliches Lateinamerika Kolloquium, Abstracts, 39.

Frisicale, M.C., Dimieri, L.V., Dristas, J.A., 2001. Cinemática de las milonitas del basamento en Boca de la Sierra, Sierras de Azul, Buenos Aires. Revista de la Asociación Geológica Argentina, 56(3), 319-330.

Frisicale, M.C., Dimieri, L.V., Dristas, J.A., 2004. Deformación dúctil en el Cerro Negro, megacizalla de Azul, Tandilia, Provincia de Buenos Aires. Asociación Geológica Argentina Serie D, 7, 82-88.

Frisicale, M.C., Martínez, F.J., Dimieri, L.V., Dristas, J.A., 2005. Microstructural analysis and P-T conditions of the Azul megashear zone, Tandilia, Buenos Aires province, Argentina. Journal of South American Earth Sciences, 19, 433-444.

Frisicale, M., Dimieri, L., Dristas, J., 2006. Pseudotaquilitas en la megacizalla de Azul, Tandilia. Asociación Geológica Argentina Serie D, 10, 174-179.

Frisicale, M., Dimieri, L., Araujo, V., Dristas, J., 2010. Mecanismos de deformación en la transición milonitas/striped gneiss y milonitas/ultramilonitas en las Sierras de Azul, cratón del Río de la Plata, Buenos Aires. Revista de la Asociación Geológica Argentina, 67, 4-18.

González Bonorino, F., Zardini, R., Figueroa, M., Limousin, T., 1956. Estudio geológico de las Sierras de Olavarría y Azul (Prov. De Buenos Aires). Lemit, Serie 2, 63, 1-22.

Grant, J.A., 1986. The isocon diagram a simple solution to Gresen´s equation for metasomatic alteration. Economic Geology, 81, 1976-1982.

Hartmann, L.S., Santos, J.O.S., Cingolani, C.A., McNaughton, N.J., 2002. Two Palaeoproterozoic orogenies in the evolution of the Tandilia Belt, Buenos Aires, as evidenced by Zircon U-Pb SHRIMP geochronology. International Geology Review, 44, 528-543.

Iacumin, M., Piccirillo, E.M., Girardi, V.A.V., Teixeira, W., Bellieni, G., Echeveste, H., Fernández, R., Pinese, J.P.P., Ribot, A., 2001. Early Proterozoic calc-alkaline and middle Proterozoic tholeiitic dyke swarms from central-eastern Argentina: petrology, geochemistry, Sr-Nd isotopes and tectonic implications. Journal of Petrology, 42(11), 2109-2143.

Kruse, R., Stünitz, H., 1999. Deformation mechanisms and phase distribution in mafic high-temperature mylonites from the Jotun Nappe, southern Norway. Tectonophysics, 303, 223-249.

Lin, A., 1994. Glassy pseudotachylyte veins from Fuyun fault zone, northwest China. Journal of Structural Geology, 16, 71-83.

Lin, A., Shimamoto, T., 1998. Selective melting processes as inferred from experimentally-generated pseudotachylytes. Journal of Asian Earth Sciences, 16, 533-545.

Lin, A., 1999. Roundness of clasts in pseudotachylytes and cataclastic rocks as an indicator of frictional melting. Journal of Structural Geology, 21, 473-478.

Lin, A., Sun, Z., Yang, Z., 2003. Multiple generations of pseudotachylyte in the brittle to ductile regimes, QinlingDabie ultrahigh-pressure metamorphic complex, central China. The Island Arc, 12, 423-435.

Lin, A., Maruyama, T., Aaron, S., Michibayashi, K., Camacho, A., Kano, K., 2005. Propagation of seismic slip from brittle to ductile crust: Evidence from pseudotachylyte of the Woodroffe thrust, central Australia. Tectonophysics, 402, 21-35.

Lin, A., 2008a. Fossil Earthquakes: Formation and Preservation of Pseudotachylytes. Berlin, Springer, 348pp.

Lin, A., 2008b. Seismic slip in the lower crust inferred from granulite-related pseudotachylyte in the Woodroffe thrust, Central Australia. Pure and Applied Geophysics, 165, 215-233.

Maddock, R.H., 1992. Effects of lithology, cataclasis and melting on the composition of fault-generated pseudotachylytes in Lewisian gneiss, Scotland. Tectonophysics, 204, 261-278.

Magloughlin, J.F., 1992. Microstructural and chemical changes associated with cataclasis and frictional melting at shallow crustal levels: the cataclasite-pseudotachylyte connection. Tectonophysics, 204, 243-260.

McKenzie, D., Brune, J.N., 1972. Melting on fault planes during large earthquakes. Geophysical Journal of the Royal Astronomical Society, 29, 65-78.

McNulty, B., 1995. Pseudotachylyte generated in the semi-brittle regimes, Bench Canyon shear zone, central Sierra Nevada.

Journal of Structural Geology, 17, 1507-1521.

O’Connor, J.T., 1965. Granite Classification using the Ab-An-Or diagram. In: Rollinson, H.R. (ed.). Using geochemical data: Evaluation, Presentation, Interpretation. Longman, 58-60.

O’Hara, K.D., 1992. Major and trace elements constrains on the petrogenesis of a fault related pseudotachylyte, western Blue Ridge province, North Carolina. Tectonophysics, 204, 270-288.

O’Hara, K.D., Sharp, Z.D., 2001. Chemical and oxygen isotope composition of natural and artificial pseudotachylyte: role of water during frictional fusion. Earth and Planetary Science Letters, 184, 393-406.

Otsuki, K., Hirono, T., Omori, M., Sakaguchi, M., Tanigawa, W., Lin, W., Soh, W., Rong, S., 2009. Analyses of pseudotachylyte from Hole-B of Taiwan Chelungpu Fault Drilling Project (TCDP); their implications for seismic slip behaviors during the 1999 Chi-Chi earthquake. Tectonophysics, 469, 13-24.

Pankhurst, R.J., Ramos, V.A., Linares, E., 2003. Antiquity of the Río de la Plata craton in Tandilia, southern Buenos Aires province, Argentina. Journal of South American Earth Sciences, 16, 5-13.

Passchier, C., Trouw, R., 2005. Microtectonics. Berlin, Springer Verlag, 366pp.

Powell, R., Holland, T.J.B., Worley, B., 1998. Calculating phase diagrams in volving solid solutions via non-linear equations, with examples using Thermocalc. Journal of Metamorphic Geology, 16, 577-588.

Pryer, L., 1993. Microstructures in feldspars from a major crustal thrust zone: the Grenville Front, Notario, Canada. Journal of Structural Geology, 15, 21-36.

Ramos, V.A., 1999. Rasgos estructurales del territorio Argentino. Evolución tectónica de la Argentina. In: Caminos, R. (ed.). Geología Argentina. Buenos Aires, Anales, Servicio Geológico Minero Argentino (SEGEMAR), 29(24), 715-784.

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

Reynolds, S.J., Goodwin, L.B., Lister, G.S., Ellzey, P.D., Ferranti, C.J., 1998. Development of ultramylonite from pseudotachylyte in a metamorphic core complex. In: Snoke, A., Tullis, J., Todd, V. (eds.). Fault-related rocks. A photographic Atlas. Princeton University Press, 124-125.

Sibson, R.H., 1975. Generation of pseudotachylyte by ancient seismic faulting. Geophysical Journal of the Royal Astronomical Society, 43, 775-794.

Sibson, R.H., 1980. Transient discontinuities in ductile shear zones. Journal of Structural Geology, 2, 165-171.

Spray, J.G., 1992. A physical basis for the frictional melting of some rock-forming minerals. Tectonophysics, 204, 205-221.

Spray, J.G., 1995. Pseudotachylyte controversy: Fact or friction? Geology, 23, 1119-1122.

Swanson, M.T., 1992. Fault structure, wear mechanisms and rupture processes in pseudotachylyte generation. Tectonophysics, 204, 223-242.

Takagi, H., Goto, K., Shigematsu, N., 2000. Ultramylonite bands derived from cataclasite and pseudotachylyte in granites, northeast Japan. Journal of Structural Geology, 22, 1325-1339.

Teixeira, W., Pinese, J.P.P., Iacumin, M., Girardi, V.A.V., Piccirillo, E.M., Echeveste, H., Ribot, A., Fernández, R., Renne, P.R., Heaman, L.M., 2001. Geochronology of calc-alkaline and tholeiitic dyke swarms of Tandilia, Río de la Plata craton, and their role in the paleoproterozoic tectonics. Pucón (Chile), III South American Symposium of Isotope Geology, Santiago de Chile, Extended abstract, CD-Rom, Servicio Nacional de Geología y Minería (SENARGEO-MIN), 257-260.

Teruggi, M.E., Kilmurray, J.O., Dalla Salda, L., 1973. Los dominios tectónicos de la región de Tandil. Anales Sociedad Científica Argentina, 95(1-2), 81-96.

Teruggi, M., Kilmurray, J., Dalla Salda, L., 1974. Los dominios tectónicos de la región de Balcarce. Revista de la Asociación Geológica Argentina, 29(3), 265-276.

Thompson, L.M., Spray, J.G., 1996. Pseudotachylyte petrogenesis: constraints from the Sudbury impact structure. Contributions to Mineralogy and Petrology, 125(4), 359-374.

Trouw, R.A.J., Passchier, C.W., Wiersma, D.J., 2010. Atlas of mylonites and related microstructures. Berlin, Springer Verlag, 322pp.

Warr, L.N., van der Pluijm, B.A., Peacor, S.R., Hall, S.M., 2003. Frictional melt pulses during a ~1.1Ma earthquake along the Alpine Fault, New Zealand. Earth and Planetary Science Letters, 209, 39-52.

Wenk, H.R., Jonson, L.R., Ratschbacher, L., 2000. Pseudotachylytes in the Eastern Peninsular Ranges of California. Tectonophysics, 321, 253-277.

Wenk, H.R., Weiss, L.E., 1982. Al-rich calcic pyroxene in pseudotachylyte: an indicator of high pressure and high temperature? Tectonophysics, 84, 329-341.

Downloads

Published

2012-07-20

Issue

Section

Articles