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Boletín de la Sociedad Geológica Mexicana
versión impresa ISSN 1405-3322
Bol. Soc. Geol. Mex vol.59 no.1 Ciudad de México jun. 2007
https://doi.org/10.18268/bsgm2007v59n1a7
Artículos
Disolución y precipitación de carbonatos en sistemas hidrotermales. Implicaciones en la génesis de depósitos tipo MVT
Dissolution and precipitation of carbonates in hydrothermal systems. Implications in the genesis of MVT deposits
1Departament de Geologia, Facultat de Ciéncies, Universitat Autónoma de Barcelona, 08193-Bellaterra, Cataluña, España. merce.corbella@uab.es.
2Institut de Ciències de la Terra Jaume Almera, Consejo Superior de Investigaciones Científicas, c/ Martí i Franquès s/n, 08028-Barcelona, Cataluña, España
El origen de la porosidad secundaria en carbonatos profundos, observada tanto en reservorios de hidrocarburos como en depósitos de Zn-Pb de tipo Mississippi Valley (MVT), es difícil de justificar, ya que los datos cinéticos y termodinámicos sugieren que las soluciones calientes que circulan por carbonatos están equilibradas con ellos y, por lo tanto, no los disuelven. Esta aparente paradoja puede ser explicada a partir del estudio e interpretación de las texturas minerales en los depósitos MVT. Algunas de ellas sugieren simultaneidad entre los fenómenos de disolución de la roca encajante carbonatada y de precipitación de sulfuros, sulfatos y carbonatos, en tanto que otras texturas indican un crecimiento de cristales muy rápido y en espacios abiertos. La mezcla de dos soluciones hidrotermales concilia las observaciones texturales con los datos experimentales y teóricos.
Se han realizado los cálculos correspondientes de transporte reactivo en el contexto de formación de depósitos MVT. Los resultados obtenidos muestran que la mezcla de una salmuera ácida, saturada en carbonato, con un agua subterránea más diluida y alcalina, también saturada en carbonato, es otra solución de química intermedia pero mayoritariamente subsaturada en carbonato, y, por lo tanto, capaz de disolver la roca y formar cavidades en algunas decenas de miles de años. Cuando los fluidos que se mezclan transportan metales y sulfhídrico, precipitan sulfuros alrededor de las cavidades; la porosidad generada a partir de la reacción acoplada entre la precipitación de sulfuros y disolución de carbonatos no es suficiente para generar las cavidades observadas, pero sí para evitar el blindaje de ésta por sulfuros. Si la solución rica en azufre contiene más sulfato que sulfhídrico (es ligeramente oxidante) pueden depositarse también sulfatos en el espacio abierto generado. Diferentes proporciones de los fluidos extremos de la mezcla dan lugar a cavidades de formas diferentes, las cuales tienden a alargarse en las direcciones de menor flujo. El mismo proceso de mezcla de soluciones hidrotermales en una roca carbonatada puede resultar en la formación de cavidades simultáneamente a la precipitación de sulfuros y relleno de sulfatos.
Palabras clave: texturas en MVT; disolución de carbonatos; karst hidrotermal; simulaciones numéricas; transporte reactivo
The formation of secondary porosity in deep carbonates as observed in hydrocarbon reservoirs or Zn-Pb Mississippi Valley type (MVT) deposits is difficult to explain as kinetic and thermodynamic data suggest that low temperatures hydrothermal solutions flowing through carbonate rocks are in equilibrium with them and dissolution cannot occur. Textural studies in MVT deposits provide the clue to the paradox. Some textures indicate that dissolution of the carbonate host rock was concomitant with sulfide, sulfate and carbonate porosity filling; however, other textures point to a rapid growth of crystals in open spaces. The mixing of two hydrothermal solutions conciliates the observational features with experimental and theoretical data. Numerical methods used to perform the calculations of reactive transport in the context of MVT ore formation show that mixing between an acidic brine with dilute and alkaline groundwater, both independently saturated with respect to carbonate forms with an intermediate chemistry but mostly undersaturated with respect to carbonate. Therefore, the mixture is carbonate-corrosive and is able to build cavities within a time span of some tens of thousands of years. Sulfides precipitate surrounding cavity walls when the mixing fluids carry metals and sulfur; this reaction is concomitant with an increase in porosity. Such porosity is not large enough to explain the developed cavity but is sufficient to prevent its armoring by sulfides. Sulfate may precipitate in the open spaces formed whenever the sulfur-rich fluid carries more sulfate than sulfide (a slightly oxidizing fluid). Mixing of different proportions of end-member fluids results in cavities of uneven shapes, as cavities tend to enlarge towards the smaller flux direction. From the textural and reactive transport study in MVTs we conclude that cavity formation, sulfide precipitation and sulfate filling may be generated by the same major process of hydrothermal fluid mixing.
Keywords: MVT textures; carbonate dissolution; hydrothermal karst; numerical simulations; reactive transport
Referencias bibliográficas
Anderson, G.M., 1975, Precipitation of Mississippi Valley-type ores: Economic Geology, 70, 937-942. [ Links ]
Anderson, G.M., Garven G., 1987, Sulfate-sulfide-carbonate associations in Mississippi Valley-type lead-zinc deposits: Economic Geology, 82, 482-488. [ Links ]
Appold, M.S., Garven, G., 1999, The hydrology of ore formation in the Southeast Missouri District: numerical models of topography-driven fluid flow during the Ouachita Orogeny. Economic Geology, 94, 913-936. [ Links ]
Appold, M.S., Garven, G., 2000, The hydrology of ore formation in the Southeast Missouri District: numerical models of topography-driven fluid flow during the Ouachita Orogeny: Economic Geology, 94, 913-936. [ Links ]
Ayora, C., Taberner, C., Saaltink, M.W., Carrera, J., 1998, The genesis of dedolomites: a discussion based on textures and reactive transport modeling. Journal of Hydrology, 209, 346-365. [ Links ]
Back, W., Hanshaw, B.B., Pyle, T.E., Plummer, L.N., Weidie, A.E., 1979, Geochemical significance of groundwater discharge and carbonate solution to the formation of Caleta Xel Ha, Quintana Roo, Mexico: Water Resources Research, 15, 1521-1535. [ Links ]
Barnes, H.L., 1979, Solubilities of Ore Minerals, In: Barnes, H.L. (ed.), Geochemistry of Hydrothermal ore deposits: New York, Wiley and Sons, 404-460. [ Links ]
Barnes, H.L., 1983, Ore Depositing Reactions in Mississippi Valley-Type Deposits, : Kisvarsanyi, G., Grant, S.K., Pratt, W.P., Koenig, J.W., (eds.), International conference on Mississippi Valley type lead-zinc deposits, Proceedings volume: Rolla, University of Missouri-Rolla Press, 77-85. [ Links ]
Bethke, C.M., 1986, Hydrologic constraints on the genesis of the Upper Mississippi Valley mineral district from Illinois basin brines. Economic Geology, 81, 233-249. [ Links ]
Bottrell, S.H., Crowley, S., Self, C., 2001, Invasion of a karst aquifer by hydrothermal fluids: evidence from stable isotopic composition of cave mineralization: Geofluids, 1, 103-121. [ Links ]
Brown, J.S., 1970, Mississippi Valley type lead-zinc ores: A review and sequel to the “Behre Symposium”. Mineralium Deposita, 5, 103-119. [ Links ]
Canals, A., Cardellach, E., Moritz, R., Soler, A., 1999, The influence of enclosing rock type on barite deposits, eastern Pyrenees, Spain: fluid inclusion and isotope (Sr, S, O, C) data: Mineralium Deposita, 34, 199-210. [ Links ]
Corbella, M., Ayora, C. , 2003, Role of fluid mixing in deep dissolution of carbonates: Geologica Acta, 1, 305-313 (available online at http://www. geologica-acta.com). [ Links ]
Corbella, M. , Ayora, C. , Cardellach, E. , 2004, Hydrothermal mixing, carbonate dissolution and sulphide precipitation in Mississippi Valley-type deposits: Mineralium Deposita, 39, 344-357. [ Links ]
Corbella, M. , Ayora, C. , Cardellach, E. , Soler, A. , 2006, Reactive transport modeling and hidrotermal karst genesis: The example of Rocabruna barite deposit (Eastern Pyrenees): Chemical Geology, 233, 113-125. [ Links ]
Garven, G. , Freeze, R.A., 1984, Theoretical analysis of the role of groundwater flow in the genesis of stratabound ore deposits: 2. Quantitative results: American Journal of Science 284, 1125- 1174. [ Links ]
Garven, G. , Ge, S., Person, M.A., Sverjensky, D.A., 1993, Genesis of stratabound ore deposits in the midcontinent basins of North America. 1. The role of regional groundwater flow. American Journal of Science, 295, 497-568. [ Links ]
Giordano, T.H., Barnes, H.L,1981, Lead transport in Mississippi Valleytype ore solutions: Economic Geology, 76, 2200-2211. [ Links ]
González-Sánchez, F., Puente-Solís, R., González-Partida, E., Camprubí, A., 2007, Estratigrafía del Noreste de México y su relación con los yacimientos estratoligados de fluorita, barita, celestina y Zn-Pb: Boletín de la Sociedad Geológica Mexicana, LIX, 43-62. [ Links ]
Grandia, F., Cardellach, E. , Canals, A. , Banks, D., 2003, Geochemistry of the fluids related to epigenetic carbonate-hosted Zn-Pb deposits in the Maestrat Basin (Eastern Spain): Fluid inclusion and isotope (Cl, C, O, S, Sr) evidences: Economic Geology, 98, 933-954. [ Links ]
Hanor, J.S., 2001, Reactive transport involving rock-buffered fluids of varying salinity: Geochimica et Cosmochimica Acta, 65, 3721- 3732. [ Links ]
Helgeson, H.L., Kirkham, D.H., 1974, Theoretical prediction of the thermodynamic behavior of aqueous electrolytes at high pressures and temperatures. II: Debye-Hückel parameters for activity coefficients and relative partial molal properties. American Journal of Science, 274, 1199-1261. [ Links ]
Heyl, A.V., Agnew, A.F., Lyons, E.J., Behre, C.H., 1959, The Geology of the Upper Mississippi Valley zinc-lead district: U.S. Geological Survey Professional Paper 309. [ Links ]
Hill C.A., 1995, H2S-related porosity and sulfuric acid oil-field karst, In: Budd, D.A., Saller, A.J., Harris, P.M. (eds), Unconformitites and porosity in carbonate strata: AAPG Memoir 63. [ Links ]
Kendrick, M.A., Burgess, R., Pattrick, R.A.D., Turner, G., 2002a, Hydrothermal fluid origins in a fluorite-rich Mississippi Valley-type district: combined noble gas (He, Ar, Kr) and halogen (Cl, Br, I) analysis of fluid inclusions from the South Pennine ore field, United Kingdom: Economic Geology, 97, 435-451. [ Links ]
Kendrick, M.A. , Burgess, R. , Leach, D., Pattrick, R.A.D. , 2002b, Hydrothermal fluid origins in a Mississippi Valley-type ore district: combined noble gas (He, Ar, Kr) and halogen (Cl, Br, I) analysis of fluid inclusions from the Illinois-Kentucky fluorspar district, Viburnum Trend, and Tri-State districts, mid-continent United States: Economic Geology, 97, 453-469. [ Links ]
Kesler, S.E., 1996, Appalachian Mississippi Valley-type deposits: paleoaquifers and brine provinces, In: Sangster, D.F. (ed.), Carbonate-hosted lead-zinc deposits: Society of Economic Geology Special Publication, 4, 29-57. [ Links ]
Luttge, A., Winkler, U., Lasaga, A. C., 2003, An interferometric study of the dolomite dissolution: a new conceptual model for mineral dissolution: Geochimica et Cosmochimica Acta, 67, 1099-1116. [ Links ]
McLimans, R.K., 1977, Geological, fluid inclusions, and stable isotopes studies of the Upper Mississippi Valley zinc-lead district, Southwest Wisconsin: PhD thesis, Penn State University, 175 p [ Links ]
Naumov, G.B., Ryzhenko, B.N., Khodakovsky, I.L, 1974, Handbook of thermodynamic data: U.S. Geological Survey, WRD-4-001. Ohle, E.L., 1980, Some considerations in determining the origin of ore deposits of the Mississippi Valley type- part II. Economic Geology, 75, 161-172. [ Links ]
Plumlee, G.S., Leach, D. L., Hofstra, A.H., Landis, G.P., Rowan, E.L., Viets, J.G., 1994, Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, U.S. Midcontinent: Economic Geology, 89, 1361-1383. [ Links ]
Saaltink, M.W. , Ayora, C. , Carrera, J. , 1998, A mathematical formulation for reactive transport that eliminates mineral concentrations: Water Resources Research, 34, 1649-1656. [ Links ]
Saaltink, M.W. , Batlle, F., Ayora, C. , Carrera, J. , Olivella, S., 2004, RETRASO, a code for modeling reactive transport in saturated and unsaturated porous media: Geologica Acta, 2-3, 235-251 (available online at http://www.geologica-acta.com ). [ Links ]
Salas, J., Taberner, C. , Esteban, M., Ayora, C. , 2007, Hydrothermal dolomitization, mixing corrosion and deep burial porosity formation: numerical results from 1-D reactive transport models; Geofluids, 7, 99-111. [ Links ]
Sandford, W.E., Konikow, L.F., 1989, Simulation of calcite dissolution and porosity changes in saltwater mixing zones in coastal aquifers: Water Resources Research, 25, 655-667. [ Links ]
Sass-Gustkiewicz, M., Dzulynski, S., Ridge, J.D., 1982, The emplacement of zinc-lead sulfide ores in the Upper Silesian district - a contribution to the understanding of Mississippi Valley-type deposits: Economic Geology, 77, 392-412. [ Links ]
Shelton, K.L., Bauer, R.M., Gregg, J.M., 1992, Fluid-inclusion studies of regionally extensive epigenetic dolomites, Bonneterre Dolomite (Cambrian), southeast Missouri: evidence of multiple fluids during dolomitization and lead-zinc mineralization: Geological Society of America Bulletin, 104, 675-683. [ Links ]
Soler, A. , Ayora, C. , 1985, La mineralització kàrstica (Ba, Cu, Pb, Zn, Sb) de Rocabruna i de Can Pubill, Pirineu Oriental: geologia, morfologia i gènesi; Acta Geologica Hispanica, 20, 107-122. [ Links ]
Steefel, C.I., MacQuarrie, K.T.B., 1996, Approaches to modeling of reactive transport in porous media. In: Lichtner, P.C., Steefel, C.I. , Oelkers, E.H., eds. Reactive transport in porous media: Reviews in Mineralogy, 34, 83-130. [ Links ]
Sverjensky, D.A. , 1986, Genesis of Mississippi Valley-type lead-zinc deposits: Annual Review of Earth and Planetary Sciences, 14, 177-199. [ Links ]
Teng, H.H., Dove, P.M., DeYoreo, J.J., 2000, Kinetics of calcite growth: surface processes and relationships to macroscopoic rate laws: Geochimica et Cosmochimica Acta, 64, 2255-2266. [ Links ]
Wigley, T.M., Plummer, L.N. , 1976, Mixing of carbonate waters: Geochimica et Cosmochimica Acta, 40, 989-995. [ Links ]
Wolery, T.J., 1992, EQ3NR, a computer program for geochemical aqueous speciation-solubility calculations: Theoretical manual, user’s guide and related documentation (Version 7.0); Publication UCRLMA- 110662 Pt III, Lawrence Livermore Laboratory, Livermore, California, USA. [ Links ]
Recibido: 25 de Mayo de 2007; Revisado: 09 de Agosto de 2007; Aprobado: 15 de Agosto de 2007
Este es un artículo publicado en acceso abierto bajo una licencia Creative Commons
