Abstract
A combined Sr, O and C isotope study has been carried out in the Pucará basin, central Peru, to compare local isotopic trends of the San Vicente and Shalipayco Zn-Pb Mississippi Valley-type (MVT) deposits with regional geochemical patterns of the sedimentary host basin. Gypsum, limestone and regional replacement dolomite yield 87Sr/86Sr ratios that fall within or slightly below the published range of seawater 87Sr/86Sr values for the Lower Jurassic and the Upper Triassic. Our data indicate that the Sr isotopic composition of seawater between the Hettangian and the Toarcian may extend to lower 87Sr/86Sr ratios than previously published values. An 87Sr-enrichment is noted in (1) carbonate rocks from the lowermost part of the Pucará basin, and (2) different carbonate generations at the MVT deposits. This indicates that host rocks at MVT deposits and in the lower-most part of the carbonate sequence interacted with 87Srenriched fluids. The fluids acquired their radiogenic nature by interaction with lithologies underlying the carbonate rocks of the Pucará basin. The San Ramón granite, similar Permo-Triassic intrusions and their clastic derivatives in the Mitu Group are likely sources of radiogenic 87Sr. The Brazilian shield and its erosion products are an additional potential source of radiogenic 87Sr. Volcanic rocks of the Mitu Group are not a significant source for radiogenic 87Sr; however, molasse-type sedimentary rocks and volcaniclastic rocks cannot be ruled out as a possible source of radiogenic 87Sr. The marked enrichment in 87Sr of carbonates toward the lower part of the Pucará Group is accompanied by only a slight decrease in δ 18O values and essentially no change in δ 13C values, whereas replacement dolomite and sparry carbonates at the MVT deposits display a coherent trend of progressive 87Sr-enrichment, and 18O- and 13C-depletion. The depletion in 18O in carbonates from the MVT deposits are likely related to a temperature increase, possibly coupled with a 18O-enrichment of the ore-forming fluids. Progressively lower δ 13C values throughout the paragenetic sequence at the MVT deposits are interpreted as a gradually more important contribution from organically derived carbon. Quantitative calculations show that a single fluid-rock interaction model satisfactorily reproduces the marked 87Sr-enrichment and the slight decrease in δ 18O values in carbonate rocks from the lower part of the Pucará Group. By contrast, the isotopic covariation trends of the MVT deposits are better reproduced by a model combining fluid mixing and fluid-rock interaction. The modelled ore-bearing fluids have a range of compositions between a hot, saline, radiogenic brine that had interacted with lithologies underlying the Pucará sequence and cooler, dilute brines possibly representing local fluids within the Pucará sequence. The composition of the local fluids varies according to the nature of the lithologies present in the neighborhood of the different MVT deposits. The proportion of the radiogenic fluid in the modelled fluid mixtures interacting with the carbonate host rocks at the MVT deposits decreases as one moves up in the stratigraphic sequence of the Pucará Group.
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Al-Aasm, I.S., Taylor, B.E., South B. (1990) Stable isotope analysis of multiple carbonate samples using selective acid extraction. Chem. Geol. 80:119–125
Anderson, G.M., Macqueen, R.W. (1988) Mississippi Valley-type lead-zinc deposits. In: Roberts, R.G., Sheahan, P.A. (eds.) Ore deposit models. Geosciencc Canada Reprint Series 3: 79–90
Banner, J.L., Hanson, G.N. (1990) Calculation of simultaneous isotopic and trace clement variations during water-rock interaction with applications to carbonate diagenesis. Geochim. Cosmochim. Acta 54: 3123–3137
Bannner, J.L., Hanson, G.N., Meyers, W.J. (1988) Water-rock interaction history of regionally extensive dolomites of the Burlington-Keokuk Formation (Mississippian): isotopic evidence. In: Shukla, V., Baker, P.A. (eds.) Sedimentology and geochemistry of Dolostones. Soc. Econ. Paleontologists Mineralogists Spec. Publ. 43: 97–113
Baumgartner, L.P., Rumble, D. (1988) Transport of stable isotope. I. Development of a kinetic continuum theory for stable isotope transport. Contrib. Mineral. Petrol. 98: 417–430
Beales, F.W., Hardy, J.L. (1980) Criteria for the recognition of diverse dolomite type with an emphasis on studies on host rocks for Mississippi Valley-Type ore deposits. In: Zenger, D.H., Dunham, J.B., Ethington, R.L. (eds.) Concepts and models of dolomitization. Soc. Econ. Paleontologists. Mineralogists Spec. Publ. 28: 197–213
Bethke, C.M., Marshak, S. (1990) Brine migrations across North America — The plate tectonics of groundwater. Ann. Rev. Earth Planet. Sci. 18: 287–315
Capdevila, R., Mégard, F., Paredes, J., Vidal P. (1977) Le batholite de San Ramón, cordillère orientale du Pérou central. Geol. Rundsc. 66: 434–446
Carlier, G., Grandin, G., Laubacher, G., Marocco, R., Mégard, F. (1982) Present knowledge of the magmatic evolution of the Eastern Cordillera of Peru. Earth-Sci. Rev. 18: 253–283
Carothers, W.W., Kharaka, Y.K. (1980) Stable carbon isotopes of HCO −3 in oil-field waters-implications for the origin of CO2. Geochim. Cosmochim. Acta 44: 323–332
Chaudhuri, S. (1978) Strontium isotopic composition of several oil-field brines from Kansas and Colorado. Geochim. Cosmochim. Acta 42: 329–331
Chaudhuri, S., Clauer, N. (1993) Strontium isotopic composition and potassium and rubidium contents of formation waters in sedimentary basins: clues to the origin of the solutes. Geochim. Cosmochim. acta 57: 429–437
Clendenin, C.W., Duane, M.J. (1990) Focused fluid flow and Ozark Mississippi Valley-type deposits. Geology 18: 116–119
Emrich, K., Erhalt, D.H., Vogel, J.C. (1970) Carbon isotope fractionation during the precipitation of calcium carbonate. Earth Planet. Sci. Lett. 8: 363–371
Farr, M.R. (1992) Geochemical variation of dolomite cement within the Cambrian Bonneterre Formation, Missouri: evidence for fluid mixing. J. Sediment. Petrol. 62: 636–651
Fontboté, L. (1990) Stratabound ore deposits in the Pucará basin. An overview. In: Fontboté, L., Amstutz, G.C., Cardozo, M., Cedillo, E., Frutos, J. (eds.) Stratabound ore deposits in the Andes. Springer, Berlin Heidelberg New York, pp. 253–266
Fontboté, L., Gorzawski, H. (1990) Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru: geological and isotopic (Sr, O, C, S) evidences. Econ. Geol. 85: 1402–1437
Fontboté, L., Gunnesch, K.A., Baumann, A. (1990) Metal sources in Stratabound ore deposits in the Andes (Andean cycle) -Lead isotopic constraints. In: Fontboté, L., Amstutz, G.C., Cardozo, M., Cedillo, E., Frutos, J. (eds.) Stratabound ore deposits in the Andes. Springer, Berlin Heidelberg New York, pp. 759–773
Franklyn, M.T., McNutt, R.H., Kamineni, D.C., Gascoyne, M., Frape, S.K. (1991) Groundwater 87Sr/86Sr values in the Eye-Dashwa Lakes pluton, Canada: evidence for plagioclase-water reaction. Chem. Geol. 86: 111–122
Friedman, I., O'Neil, J.R. (1977) Compilation of stable isotope fractionation factors of geochemical interest. In: Fleischer, M. (ed.) Data of Geochemistry. 6th edn. U.S. Geological Survey Professional Paper 440–KK, 12 pp
Garven, G., Gee, 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. Am. J. Sci. 293: 497–568
Ghazban, F., Schwarcz, H.P., Ford, D.C. (1992) Multistage dolomitization in the Society Cliffs Formation, northern Baffin Island, Northwest Territories, Canada. Can. J. Earth Sci. 29: 1459–1473
Gorzawski, H., Fontboté, L., Sureau, A., Calvez, J.Y. (1989) Strontium isotope trends during diagenesis in ore-bearing carbonate basins. Geol. Rundsc. 78: 269–290
Japan International Cooperation Agency (1976) Report on geological survey of the Cordillera Oriental, central Peru. Unpublished report, Japan Mining Agency, Japan International Cooperation Agency, Lima, vol. 2, pp. 39–40
Kaufman, J., Meyers, W.J., Hanson, G.N. (1990) Burial cementation in the Swan Hills formation (Devonian), Rosevear field, Alberta, Canada. J. Sediment. Petrol 60: 918–939
Kaufman, J., Hanson, G.N., Meyers, W.J. (1991) Dolomitization of the Devonian Swan Hills formation, Rosevear field, Alberta, Canada. Sedimentology 38: 41–66
Kesler, S.E. (1994) Mississippi Valley-type deposits in continental margin basins: lessons from the Appalachian-Caledonian orogen. In: Fontboté, L., Boni, M. (eds.) Sediment-hosted Zn-Pb ores. Springer, Berlin Heidelberg New York, pp. 89–103
Kessen, K.M., Woodruff, M.S., Grant, N.K. (1981) Gangue mineral 87Sr/86Sr ratios and the origin of Mississippi Valley-Type mineralization. Econ. Geol. 76: 913–920
Kobe, H.W. (1990) Stratabound sulfide occurrences in the Paleozoic of the Yauli Dome, central Peru. In: Fontboté, L., Amstutz, G.C., Cardozo, M., Cedillo, E., Frutos, J. (eds.) Stratabound ore deposits in the Andes. Springer, Berlin Heidelberg New York, pp. 113–127
Koepnick, R.B., Denison, R.E., Burke, W.H., Hetherington, E.A., Dahl, D.A. (1990) Construction of the Triassic and Jurassic portion of the Phanerozoic curve of seawater 87Sr/86 Sr. Chem. Geol. 80: 327–349
Kontak, D.J., Clark, A.H., Farrar, E., Strong, D.F. (1985) The rift-associated Permo-Triassic magmatism of the Eastern Cordillera: a precursor to the Andean orogeny. In: Pitcher, W.S., Atherton, M.P., Cobbong, E.J., Beckinsale, R.D. (eds.) Magmatism at a plate edge. Blackie, Glasgow and London, pp. 36–44
Kontak, D.J., Clark, A.H., Farrar, E., Archibald, D.A., Baadsgaard, H. (1990) Late Paleozoic-early Mesozoic magmatism in the Cordillera de Carabaya, Puno, southeastern Peru: geochronology and petrogeochemistry. J. South Am. Earth Sci. 3: 213–230
Land, L.S. (1985) The origin of massive dolomite. J. Geol. Educ. 33: 112–125
Lasaga, A.C. (1984) Chemical kinetics of water-rock interactions. J. Geophys. Res. B89: 4009–4025
Leach, D.L., Rowan, E.L. (1986) Genetic link between Ouachita foldbelt tectonism and the Mississippi Valley-type lead-zinc deposits of the Ozarks. Geology 14: 931–935
Longstaffe, F.J. (1987) Stable isotope studies of diagenetic processes. In: Kyser, T.K. (ed.) Stable isotope geochemistry of low temperature fluids. Mineral. Assoc. Can. Short Course 13: 187–257
Loughman, D.L., Hallam, A. (1982) A facies analysis of the Pucará Group (Norian to Toarcian carbonates, organic-rich shale and phosphate) of central and northern Perú. Sediment. Geol. 32: 161–194
Lyons, W.A. (1968) The geology of the Carahuacra mine, Peru. Econ. Geol. 63: 247–256
Machel, H.-G. (1987) Saddle dolomite as a by-product of chemical compaction and thermochemical sulfate reduction. Geology 15: 936–940
Machel, H.-G., Mountjoy, E.W. (1986) Chemistry and environments of dolomitization — A reappraisal. Earth Sci. Reviews 23: 172–222
McCrea, J.M. (1950) On the isotopic chemistry of carbonates and a paleotemperature scale. J. Chem. Physics 18: 849–857
McNutt, R.H., Frape, Fritz, P., Jones, M.G., MacDonald, I.M. (1990). The 87Sr/86Sr values of Canadian Shield brines and fracture minerals with applications to groundwater mixing, fracture history, and geochronology. Geochim. Cosmochim. Acta 54: 205–215
Mégard, F. (1978) Etude géologique des Andes du Pérou central. ORSTOM Mémoire 86: 306 pp.
Mégard, F. (1987) Structure and evolution of the Peruvian Andes. In: Schaer, J.-P., Rodgers, J. (eds.) The anatomy of mountain ranges. Princeton University Press, Princeton, pp. 179–210
Meyers, W.J. (1989) Trace element and isotope geochemistry of zoned calcite cements, Lake Valley Formation (Mississippian, New Mexico): insights from water-rock inreaction modelling. Sediment. Geol. 65: 355–370
Mountjoy, E.W., Qing, H., McNutt, R.H. (1992) Strontium isotopic composition of devonian dolomites, Western Canada Sedimentary Basin: significance of sources of dolomitizing fluids. Appl. Geochem. 7: 59–75
Ohmoto, H., Rye, R.O. (1979) Isotopes of sulfur and carbon. In: Barnes, H.L. (ed.) Geochemistry of hydrothermal ore deposits. Wiley, New York, pp. 509–567
Pélissonnier, H. (1967) Analyse paléohydrologique des gisements stratiformes de plomb, zinc, baryte, fluorite du type “Mississippi Valley”. In: Brown, J.S. (ed.) Genesis of stratiform lead-zincbarite-fluorite deposits in carbonate rocks (The so-called Mississippi Valley type deposits). Econ. Geol. Monogr. 3: 234–252
Posey, H.H., Kyle, J.R., Jackson, T.J., Hurst, S.D., Price, P.E. (1987) Multiple fluid components of salt diapirs and salt dome cap rocks, Gulf Coast, U.S.A. Appl. Geochem. 2: 523–534
Prinz, P. (1985a) Stratigraphie und Ammonitenfauna der Pucará Gruppe (Obertrias-Unterjura) von Nord-Perú. Paleontographica 188: 153–197
Prinz, P. (1985b) Zur Stratigraphie und Ammonitenfauna der Pucará-Gruppe bei San Vicente: Dept. Junin, Perú. Newsl. Stratigr. 14: 129–141
Radke, B.M., Mathis, R.L. (1980) On the formation and occurrence of saddle dolomite. J. Sediment. Petrol. 50: 1149–1168
Rosas, S. (1994) Facies, diagenetic evolution, and sequence analysis along a SW-NE profile in the southern Pucará basin (Upper Triassic-Lower Jurassic), central Peru. Heidelberger Geowiss. Abh., Ruprecht-Karls-Universität, Heidelberg, Germany 80: 337 pp
Rosenbaum, J., Sheppard, S.M. (1986) An isotopic study of siderites, dolomites and ankerites at high temperatures. Geochim. Cosmochim. Acta 50: 1147–1150
Russel, R.D. (1977) A solution in closed form for the isotopic dilution analysis of strontium. Chem. Geol. 20: 307–314
Sangster, D.F. (1990) Mississippi Valley-type and sedex lead-zinc deposits: a comparative examination. Trans. Inst. Min. Metall. 99: B21-B42
Shelton, K.L., Bauer, R.M., Gregg, J.M. (1992) Fluid inclusion studies of regionally extensive epigenetic dolomites, Bonneterre Formation (Cambrian), southeast Missouri lead district: evidence of multiple fluids during dolomitization and lead-zinc mineralization. Geol. Soc. Am. Bull. 104: 675–683
Sheppard, S.M.F. (1986) Characterization and isotopic variations in natural waters. In: Valley, J.W., Taylor, H.P., Jr., O'Neil, J.R. (eds.) Stable isotopes in high temperature geological processes. Rev. Mineral. 16: 165–183
Sibson, R.H., Moore, J.McM., Rankin, A.H. (1975) Seismic pumping — a hydrothermal fluid transport mechanism. J. Geol. Soc. London 131: 653–659
Spangenberg, J. (1995) Geochemical (elemental and isotopic) constraints on the genesis of the Mississippi Valley-type zinc-lead deposit of San Vicente, central Peru. Terre & Environnement, Geneva, 1: 123 pp
Stueber, A.M., Pushkar, P., Hetherington, E.A. (1987) A strontium isotopic study of formation waters from the Illinois basin, USA. Appl. Geochem. 2: 477–494
Suchecki, R.K., Land, L.S. (1983) Isotopic geochemistry of burial-metamorphosed volcanogenic sediments, Great Valley sequence, northern California. Geochim. Cosmochim. Acta 47: 1487–1499
Sverjensky, D.A. (1984) Oil field brines as ore-forming solutions. Econ. Geol. 79: 23–37
Sverjensky, D.A. (1986) Genesis of Mississippi Valley-type lead-zinc deposits. Ann. Rev. Earth Planet. Sci. 14: 177–199
Szekely, T.S., Grose, L.T. (1972) Stratigraphy of the carbonate black shale and phosphate of the Pucará Group (Upper Triassic-Lower Jurassic), central Andes, Perú. Geol. Soc. Am. Bull. 83: 407–428
Vahrenkamp, V.C., Swart, P.K. (1990) New distribution coefficient for the incorporation of strontium into dolomite and its implications for the formation of ancient dolomites. Geology 18: 387–391
Veizer, J. (1983) Chemical diagenesis of carbonates: theory and applications of trace element technique. Soc. Econ. Paleontologists Mineralogists Short Course 10: 3.1–3.100
Veizer, J. (1989) Strontium isotopes in seawater through time. Ann. Rev. Earth Planet. Sci. 17: 141–167
Veizer, J., Compston, W. (1974) 87Sr/86Sr composition of seawater during the Phanerozoic. Geochim. Cosmochim. Acta 38: 1461–1484
Zheng, Y.-F., Hoefs, J. (1993) Carbon and oxygen isotopic covariations in hydrothermal calcites. Theoretical modeling on mixing processes and application to Pb-Zn deposits in the Harz Mountains, Germany, Mineral. Deposita 28: 79–89
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Moritz, R., Fontboté, L., Spangenberg, J. et al. Sr, C and O isotope systematics in the Pucará basin, central Peru. Mineral. Deposita 31, 147–162 (1996). https://doi.org/10.1007/BF00204023
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DOI: https://doi.org/10.1007/BF00204023