Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-23T16:15:03.276Z Has data issue: false hasContentIssue false
  • English
  • Français

Petrology and geochemistry of the orbicular granitoid of Sierra de Velasco (NW Argentina) and implications for the origin of orbicular rocks

Published online by Cambridge University Press:  15 December 2009

PABLO GROSSE ,
ALEJANDRO J. TOSELLI  and
JUANA N. ROSSI
PABLO GROSSE*
Affiliation:
CONICET & Fundación Miguel Lillo, Miguel Lillo 251, (4000) San Miguel de Tucumán, Argentina
ALEJANDRO J. TOSELLI
Affiliation:
Instituto Superior de Correlación Geológica – CONICET & Facultad de Ciencias Naturales, Universidad Nacional de Tucumán, Miguel Lillo 205, (4000) San Miguel de Tucumán, Argentina
JUANA N. ROSSI
Affiliation:
Instituto Superior de Correlación Geológica – CONICET & Facultad de Ciencias Naturales, Universidad Nacional de Tucumán, Miguel Lillo 205, (4000) San Miguel de Tucumán, Argentina
*
†Author for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The Velasco orbicular granitoid is a small (65 × 15 m), irregularly-shaped body that crops out within the Huaco granite, central Sierra de Velasco, NW Argentina. It consists of ellipsoid-shaped orbicules of 3 to 15 cm length immersed in an aplitic to pegmatitic matrix. The orbicules are formed by a core made up of a K-feldspar megacryst, partially to totally replaced by plagioclase, an inner shell of radial and equant plagioclase crystals, a layer of tangentially oriented biotite laths, and an outer shell of plumose plagioclase crystals, containing diffuse rings of tangentially oriented biotite. The orbicular granitoid formed in situ in a pocket of evolved and volatile-rich melt segregated from the surrounding partially crystallized Huaco granite, possibly via a filter pressing mechanism. The segregated melt entrained relatively few K-feldspar megacrysts into the pocket, leaving behind a concentration of megacrysts around the pocket. High water concentration caused effective superheating of the melt and destruction of nuclei, with only the large megacrysts surviving as solids. Sudden water-pressure loss and exsolution of the volatile phase, perhaps related to a volcanic eruption or fracturing of the surrounding granite, caused rapid undercooling of the melt. The orbicules grew in the undercooled melt by heterogeneous nucleation on the megacrysts, which acted as nucleation seeds, and crystallization of reversely zoned radial plagioclase and sporadic crystallization of tangential biotite rings according to fluctuations in its saturation. Orbicular growth gave way to crystallization of the equiaxial inter-orbicular matrix in two stages, when sufficient polymerization of the melt was attained. The time scale of formation of the orbicular granitoid was fast, possibly a matter of a few weeks or months.

Keywords

orbicular granitoidplumose plagioclasereverse zoningHuaco graniteSierra de VelascoArgentina
Type
Original Article
Information
Geological Magazine , Volume 147 , Issue 3 , May 2010 , pp. 451 - 468
Copyright
Copyright © Cambridge University Press 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bachmann, O. & Bergantz, G. W. 2004. On the origin of crystal-poor rhyolites: extracted from batholithic crystal mushes. Journal of Petrology 45, 1565–82.CrossRefGoogle Scholar
Bea, F., Pereira, M. D., Corretgé, L. G. & Fershtater, G. B. 1994. Differentiation of strongly peraluminous, perphosphorus granites. The Pedrobernardo pluton, central Spain. Geochimica et Cosmochimica Acta 58, 2609–28.CrossRefGoogle Scholar
Brigham, R. H. 1983. A fluid dynamic appraisal of a model for the origin of comb layering and orbicular structure. Journal of Geology 91, 720–4.CrossRefGoogle Scholar
Chakoumakos, B. C. & Lumpkin, G. R. 1990. Pressure–temperature constraints on the crystallization of the Harding pegmatite, Taos County, New Mexico. Canadian Mineralogist 28, 287–98.Google Scholar
Decitre, S., Gasquet, D. & Marignac, C. 2002. Genesis of orbicular granitic rocks from the Ploumanac'h Plutonic Complex (Brittany, France): petrographical, mineralogical and geochemical constraints. European Journal of Mineralogy 14, 715–31.CrossRefGoogle Scholar
Deer, W. A., Howie, R. A. & Zussman, J. 1962. Rock forming minerals, Volume 3: Sheet silicates. London: Longman, 270 pp.Google Scholar
De la Rosa, J. D., Chacón, H., Sánchez de la Campa, A., Carrasco, R. & Nieto, J. M. 2001. Metodología y análisis de elementos trazas-REE mediante ICP-MS del standard SARM 1 granito y SARM 4 norita. In Proceedings of III Congreso Ibérico de Geoquímica, pp. 435–8. Zaragoza, Spain.Google Scholar
Donaldson, C. H. 1977. Laboratory duplication of comb layering in the Rhum pluton. Mineralogical Magazine 41, 323–36.CrossRefGoogle Scholar
Durant, D. G. & Fowler, A. D. 2002. Origin of reverse zoning in branching orthopyroxene and acicular plagioclase in orbicular diorite, Fisher Lake, California. Mineralogical Magazine 66, 1003–19.CrossRefGoogle Scholar
Elliston, J. N. 1984. Orbicules: An indication of the crystallization of hydrosilicates, I. Earth Science Reviews 20, 265–344.CrossRefGoogle Scholar
Enz, R. D., Kudo, A. M. & Brookins, D. G. 1979. Igneous origin of the orbicular rocks of the Sandia Mountains, New Mexico. Bulletin of the Geological Society of America 90, 138–40.2.0.CO;2>CrossRefGoogle Scholar
Eskola, P. 1938. On the esboitic crystallization of orbicular rocks. Journal of Geology 46, 448–85.CrossRefGoogle Scholar
Fenn, P. M. 1977. The nucleation and growth of alkali feldspars from hydrous melts. Canadian Mineralogist 15, 135–61.Google Scholar
Galliski, M. 1993. La Provincia Pegmatítica Pampeana I: tipología y distribución de sus distritos económicos. Revista de la Asociación Geológica Argentina 49, 99–112.Google Scholar
Goodspeed, G. E. 1942. Orbicular rocks from Buffalo Hump, Idaho. American Mineralogist 27, 37–47.Google Scholar
Gordillo, C. E. 1979. Observaciones sobre la petrología de las rocas cordieríticas de la Sierra de Córdoba. Boletín de la Academia Nacional de Ciencias, Córdoba, Argentina 53, 3–44.Google Scholar
Grolier, J. 1961. Sur le granite orbiculaire de Tisselliline (Hoggar, Sahara Central). Bulletin de la Société Géologique de France 7, 174–81.CrossRefGoogle Scholar
Grosse, P., Rossi, J. N., Sardi, F. G. & Toselli, A. J. 2006. Química mineral de los granitos Sanagasta, Huaco y La Chinchilla, Sierra de Velasco, La Rioja, Argentina. In Proceedings of VIII Congreso de Mineralogía y Metalogenia, pp. 381–8. Buenos Aires, Argentina.Google Scholar
Grosse, P., Söllner, F., Báez, M. A., Toselli, A. J., Rossi, J. N. & de la Rosa, J. D. 2009. Lower Carboniferous post-orogenic granites in central-eastern Sierra de Velasco, Sierras Pampeanas, Argentina: U–Pb monazite geochronology, geochemistry and Sr–Nd isotopes. International Journal of Earth S ciences 98, 1001–25.Google Scholar
Higgins, M. 1999. Origin of megacrysts in granitoids by textural coarsening: a crystal size distribution (CSD) study of microcline in the Cathedral Peak Granodiorite, Sierra Nevada, California. In Understanding granites: integrating new & classical techniques (eds Castro, A., Fernández, C. & Vigneresse, J. L.), pp. 207–19. Geological Society of London, Special Publication no. 168.Google Scholar
Hort, M. 1998. Abrupt change in magma liquidus temperature because of volatile loss or magma mixing: effects on nucleation, crystal growth and thermal history of the magma. Journal of Petrology 39, 1063–76.CrossRefGoogle Scholar
Hunt, J. D. 1984. Steady state columnar and equiaxed growth of dendrites and eutectic. Materials Science and Engineering 65, 75–83.CrossRefGoogle Scholar
Lahti, S. 2005. Orbicular rocks in Finland. Espoo: Geological Survey of Finland, 177 pp.Google Scholar
Leveson, D. J. 1963. Orbicular rocks of the Lonesome Mountain area, Beartooth Mountains, Montana and Wyoming. Bulletin of the Geological Society of America 74, 1015–40.CrossRefGoogle Scholar
Leveson, D. J. 1966. Orbicular rocks: A review. Bulletin of the Geological Society of America 77, 409–26.CrossRefGoogle Scholar
Linares, E. & Quartino, B. J. 1978. Nuevas aportaciones a la génesis de las rocas orbiculares de La Rioja y el control recíproco de datos K–Ar e interpretación petrogenética. In Proceedings of VII Congreso Geológico Argentino 2, 585–93. Neuquén, Argentina.Google Scholar
Lindh, A. & Näsström, H. 2006. Crystallization of orbicular rocks exemplified by the Slättemossa occurrence, southeastern Sweden. Geological Magazine 143, 713–22.CrossRefGoogle Scholar
Lofgren, G. E. 1974 a. An experimental study of plagioclase crystal morphology: isothermal crystallization. American Journal of Science 274, 243–73.CrossRefGoogle Scholar
Lofgren, G. E. 1974 b. Temperature induced zoning in synthetic plagioclase feldspar. In The Feldspars (eds McKenzie, W. S. & Zussman, J.), pp. 362–75. Manchester: University of Manchester Press.Google Scholar
Lofgren, G. E. 1983. Effect of heterogeneous nucleation on basaltic textures: A dynamic crystallization study. Journal of Petrology 24, 229–55.CrossRefGoogle Scholar
Lofgren, G. E. & Donaldson, C. H. 1975. Curved branching crystals and differentiation in comb-layered rocks. Contributions to Mineralogy and Petrology 49, 309–19.CrossRefGoogle Scholar
London, D. 1992. The application of experimental petrology to the genesis and crystallization of granitic pegmatites. Canadian Mineralogist 30, 499–540.Google Scholar
London, D. 2005. Granitic pegmatites: an assessment of current concepts and directions for the future. Lithos 80, 281–303.CrossRefGoogle Scholar
London, D., Morgan, G. B. & Hervig, R. L. 1989. Vapor-undersaturated experiments with Macusani glass + H2O at 200 MPa, and the internal differentiation of granitic pegmatites. Contributions to Mineralogy and Petrology 102, 1–17.CrossRefGoogle Scholar
Marsh, B. D. 1988. Crystal size distribution (CSD) in rocks and the kinetics and dynamics of crystallization I. Theory. Contributions to Mineralogy and Petrology 99, 277–91.CrossRefGoogle Scholar
Marsh, B. D. 1996. Solidification fronts and magmatic evolution. Mineralogical Magazine 60, 5–40.CrossRefGoogle Scholar
Martorano, M. A. & Biscuola, V. B. 2009. Predicting the columnar-to-equiaxed transition for a distribution of nucleation undercoolings. Acta Materialia 57, 607–15.CrossRefGoogle Scholar
McBirney, A. R. & Noyes, R. M. 1979. Crystallization and layering of the Skaergaard intrusion. Journal of Petrology 20, 487–554.CrossRefGoogle Scholar
Moore, J. G. & Lockwood, J. P. 1973. Origin of comb layering and orbicular structure, Sierra Nevada batholith, California. Bulletin of the Geological Society of America 84, 1–20.2.0.CO;2>CrossRefGoogle Scholar
Nakamura, N. 1974. Determination of REE, Ba, Mg, Na and K in carbonaceous and ordinary chondrites. Geochimica et Cosmochimica Acta 38, 757–73.CrossRefGoogle Scholar
Ort, M. H. 1992. Orbicular volcanic rocks of Cerro Panizos: their origin and implications for orb formation. Bulletin of the Geological Society of America 104, 1048–58.2.3.CO;2>CrossRefGoogle Scholar
Owen, J. V. 1991. Significance of epidote in orbicular diorite from the Grenville Front zone, eastern Labrador. Mineralogical Magazine 55, 173–81.CrossRefGoogle Scholar
Propach, G. 1976. Models of filter differentiation. Lithos 9, 203–9.CrossRefGoogle Scholar
Quartino, B. J. & Villar Fabre, J. 1962. El cuerpo granítico orbicular precámbrico de la Pampa de Los Altos, sierra de Velasco. Revista de la Asociación Geológica Argentina 18, 11–41.Google Scholar
Rapela, C. W., Baldo, E. G., Pankhurst, R. J. & Saavedra, J. 2002. Cordieritite and leucogranite formation during emplacement of highly peraluminous magma: the El Pilón Granite Complex (Sierras Pampeanas, Argentina). Journal of Petrology 43, 1003–28.CrossRefGoogle Scholar
Sardi, F. G. 2005. Petrografía y caracterización de la mena del Distrito Pegmatítico Velasco, La Rioja, Argentina. Proceedings of XVI Congreso Geológico Argentino 5, 231–8. La Plata, Argentina.Google Scholar
Sardi, F. G. & Grosse, P. 2005. Consideraciones sobre la clasificación del Distrito Velasco de la Provincia Pegmatítica Pampeana, Argentina. In Proceedings of XVI Congreso Geológico Argentino 5, 239–42. La Plata, Argentina.Google Scholar
Sederholm, J. 1928. On orbicular granites, spotted and nodular granites, etc., and the rapakivi texture. Bulletin de la Commission Géologique de Finlande 83, 1–105.Google Scholar
Sinclair, W. D. & Richardson, J. M. 1992. Quartz-tourmaline orbicules in the Seagull batholith, Yukon Territory. Canadian Mineralogist 30, 923–35.Google Scholar
Siqueira, C. A., Cheung, N. & Garcia, A. 2002. Solidification thermal parameters affecting the columnar-to-equiaxed transition. Metallurgical and Materials Transactions A 33, 2107–18.CrossRefGoogle Scholar
Sisson, T. W. & Bacon, C. R. 1999. Gas-driven filter pressing in magmas. Geology 27, 613–16.2.3.CO;2>CrossRefGoogle Scholar
Söllner, F., Grosse, P., Gerdes, A., Toselli, A. J. & Rossi, J. N. 2009. U–Pb LA-ICP-MS age determinations of growth impulses in zircons from Carboniferous post-orogenic granites, Sierra de Velasco (NW-Argentina). In Proceedings of XXI Colloquium on Latin American Earth Sciences, pp. 267–70. Göttingen, Germany.Google Scholar
Sureda, R. & Viramonte, J. 1972. El granito orbicular del Cerro Reventón, Sierra de Los Comechingones, Córdoba. In Proceedings of V Congreso Geológico Argentino, pp. 215–40. Carlos Paz, Argentina.Google Scholar
Swanson, S. E. 1977. Relation of nucleation and crystal growth rate to the development of granite textures. American Mineralogist 62, 966–78.Google Scholar
Symes, R. F., Bevan, J. C. & Qasim, J. M. 1987. The nature and origin of orbicular rocks from near Deshai, Swat Kohistan, Pakistan. Mineralogical Magazine 51, 635–47.CrossRefGoogle Scholar
Tagiri, M., Oba, T. & Fujinawa, A. 2007. Radial cordierite-bearing orbicular granite formed from the melting of metapelitic hornfels in granitic magma, Tsukuba Mountains, Japan. Journal of Mineralogical and Petrological Sciences 102, 127–36.CrossRefGoogle Scholar
Tischendorf, G., Förster, H.-J. & Gottesmann, B. 1999. The correlation between lithium and magnesium in trioctahedral micas: improved equations for Li2O estimation from MgO data. Mineralogical Magazine 63, 57–74.CrossRefGoogle Scholar
Tischendorf, G., Gottesmann, B., Förster, H.-J. & Trumbull, R. B. 1997. On Li-bearing micas: estimating Li from electron microprobe analyses and an improved diagram for graphical representation. Mineralogical Magazine 61, 809–34.CrossRefGoogle Scholar
Vernon, R. H. 1985. Possible role of superheated magma in the formation of orbicular granitoids. Geology 13, 843–45.2.0.CO;2>CrossRefGoogle Scholar
Vernon, R. H. 1986. K-feldspar megacrysts in granites: phenocrysts, not porphyroblasts. Earth-Science Reviews 23, 1–63.CrossRefGoogle Scholar
Vernon, R. H. & Paterson, S. R. 2008. How late are K-feldspar megacrysts in granites? Lithos 104, 327–36.CrossRefGoogle Scholar
Villaseca, C. & Barbero, L. 1994. Chemical variability of Al–Ti–Fe–Mg minerals in peraluminous granitoid rocks from Central Spain. European Journal of Mineralogy 6, 691–710.CrossRefGoogle Scholar
Yazgan, E. & Mason, R. 1988. Orbicular gabbro from near Baskil, southeastern Turkey. Mineralogical Magazine 52, 161–73.CrossRefGoogle Scholar