Skip to main content
SpringerLink
Log in

Mineralisation of amethyst-bearing geodes in Ametista do Sul (Brazil) from low-temperature sedimentary brines: evidence from monophase liquid inclusions and stable isotopes

  • Article
  • Published:
Mineralium Deposita Aims and scope Submit manuscript

Abstract

Fluid inclusion studies in combination with hydrogen, oxygen and sulphur isotope data provide novel insights into the genesis of giant amethyst-bearing geodes in Early Cretaceous Paraná continental flood basalts at Amestita do Sul, Brazil. Monophase liquid inclusions in colourless quartz, amethyst, calcite, barite and gypsum were analysed by microthermometry after stimulating bubble nucleation using single femtosecond laser pulses. The salinity of the fluid inclusions was determined from ice-melting temperatures and a combination of prograde and retrograde homogenisation temperatures via the density maximum of the aqueous solutions. Four mineralisation stages are distinguished. In stage I, celadonite, chalcedony and pyrite formed under reducing conditions in a thermally stable environment. Low δ34SV-CDT values of pyrite (−25 to −32 ‰) suggest biogenic sulphate reduction by organotrophic bacteria. During the subsequent stages II (amethyst, goethite and anhydrite), III (early subhedral calcite) and IV (barite, late subhedral calcite and gypsum), the oxidation state of the fluid changed towards more oxidising conditions and microbial sulphate reduction ceased. Three distinct modes of fluid salinities around 5.3, 3.4 and 0.3 wt% NaCl-equivalent characterise the mineralisation stages II, III and IV, respectively. The salinity of the stage I fluid is unknown due to lack of fluid inclusions. Variation in homogenisation temperatures and in δ18O values of amethyst show evidence of repeated pulses of ascending hydrothermal fluids of up to 80–90 °C infiltrating a basaltic host rock of less than 45 °C. Colourless quartz and amethyst formed at temperatures between 40 and 80 °C, while the different calcite generations and late gypsum precipitated at temperatures below 45 °C. Calculated oxygen isotope composition of the amethyst-precipitating fluid in combination with δD values of amethyst-hosted fluid inclusions (−59 to −51 ‰) show a significant 18O-shift from the meteoric water line. This 18O-shift, high salinities of the fluid inclusions with chloride-sulphate composition, and high δ34S values of anhydrite and barite (7.5 to 9.9 ‰) suggest that sedimentary brines from deeper parts of the Guaraní aquifer system must have been responsible for the amethyst mineralisation.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14

Similar content being viewed by others

References

  • Affolter S, Fleitmann D, Leuenberger M (2014) New on-line method for water isotope analysis of speleothem fluid inclusions using laser absorption spectroscopy (WS-CRDS). Clim Past Discuss 10:429–467

    Article  Google Scholar 

  • Araújo LM, França AB, Potter PE (1999) Hydrogeology of the Mercosul aquifer system in the Paraná and Chaco-Paraná Basins, South America, and comparison with the Navajo-Nugget aquifer system, USA. Hydrogeol J 7:317–336

    Article  Google Scholar 

  • Audétat A, Günther D (1999) Mobility and H2O loss from fluid inclusions in natural quartz crystals. Contrib Mineral Petrol 137:1–14

    Article  Google Scholar 

  • Baatartsogt B, Schwinn G, Wagner T, Taubald H, Beitter T, Markl G (2007) Contrasting paleofluid systems in the continental basement: a fluid inclusion and stable isotope study of hydrothermal vein mineralization, Schwarzwald district, Germany. Geofluids 7:1–25

    Article  Google Scholar 

  • Balzer R (2003) Rio Grande do Sul, Brasilien. Landschaften – Menschen – Edle Steine. Wenzel, Marburg, pp 1–236

    Google Scholar 

  • Baretto SB, Bittar SMB (2010) The gemstone deposits of Brazil: occurrences, production and economic impact. Bol Soc Geol Mexicana 62:123–140

    Google Scholar 

  • Blount CW, Dickson FW (1973) Gypsum-anhydrite equilibria in systems CaSO4-H2O and CaSO4-NaCl-H2O. Am Miner 58:323–331

    Google Scholar 

  • Bodnar RJ (1993) Revised equation and table for determining the freezing point depression of H2O–NaCl solutions. Geochim Cosmochim Acta 57:683–684

    Article  Google Scholar 

  • Borget JN (1980) Contribution à l’étude de la genèse des minéralisations silicieuses associées aux roches basaltiques du nort-ouest de l’Uruguay. PhD thesis, University of Clermont-Ferrand, France, pp. 1–173

  • Brückert V (2004) Physiological and ecological aspects of sulfur isotope fractionation during bacterial sulfate reduction. In: Amend JP, Edwards, KJ, Lyons TW (eds) Sulfur biogeochemistry. – past and present. GSA Spec Pub 379, pp. 1-26

  • Cawley MF, McGlynn D, Mooney PA (2006) Measurement of the temperature of density maximum of water solutions using a convective flow technique. Int J Heat Mass Transfer 49:1763–1772

    Article  Google Scholar 

  • Chacko T, Cole DR, Horita J (2001) Equilibrium oxygen, hydrogen and carbon isotope fractionation factors applicable to geological systems. Rev Mineral Geochem 43:1–81

    Article  Google Scholar 

  • Clayton RN, O’Neil JR, Mayeda TK (1972) Oxygen isotope exchange between quartz and water. J Geophys Res 77:3057–3066

    Article  Google Scholar 

  • Commin-Fischer A, Berger G, Polvé M, Dubois M, Sardini P, Beaufort D, Formoso MLL (2010) Petrography and chemistry of SiO2 filling phases in the amethyst geodes from the Serra Geral Formation deposit, Rio Grande do Sul, Brazil. J South Am Earth Sci 29:751–760

    Article  Google Scholar 

  • Despretz M (1840) Le maximum de densité des liquids. Ann Chim Phys 73:296–310

    Google Scholar 

  • Duarte LC, Hartmann LA, Vasconcelos MAZ, Medeiros JTN, Theye T (2009) Epigenetic formation of amethyst-bearing geodes from Los Catalanes gemological district, Artigas, Uruguay, southern Paraná Magmatic Province. J Volcanol Geotherm Res 184:427–436

    Article  Google Scholar 

  • Duarte LC, Hartmann LA, Ronchi LH, Berner Z, Theye T, Massonne HJ (2011) Stable isotope and mineralogical investigation of the genesis of amethyst geodes in the Los Catalanes gemological district, Uruguay, southernmost Paraná volcanic province. Miner Depos 46:239–255

    Article  Google Scholar 

  • Fall A, Rimstidt JD, Bodnar RJ (2009) The effect of fluid inclusion size on determination of homogenization temperature and density of liquid-rich aqueous inclusions. Amer Mineral 94:1569–1579

    Article  Google Scholar 

  • Fontes JC, Gonfiantini R (1967) Fractionnement isotopique de l’hydrogène dans l’eau de crystallization de gypse. Comptes Rend Acad Sci Paris Ser II 265:4–6

    Google Scholar 

  • Frank HT, Gomes MEB, Formoso ML (2009) Review of the areal extend and the volume of the Serra Geral Formation, Paraná Basin, South America. Pesquisas em Geociências 36:49–57

    Google Scholar 

  • Gastmanns D, Chang KH, Hutcheon I (2010) Stable isotopes (2H, 18O and 13C) in groundwaters from the northwestern portion of the Guarani Aquifer System (Brazil). Hydrogeol J 18:1497–1513

    Article  Google Scholar 

  • Giesemann A, Jäger HJ, Norman AL, Krouse HR, Brand WA (1994) On-line sulfur isotope determination using an element analyzer coupled to mass spectrometer. Analyt Chem 66:2816–2819

    Article  Google Scholar 

  • Gilg HA (2012) In the Beginnings: The Origins of Amethyst. In: Gilg HA, Liebetrau S, Staebler G, Wilson T (eds) Amethyst—uncommon vintage. Lithographie, Denver, Co, pp 10–13

    Google Scholar 

  • Gilg HA, Morteani G, Kostitsyn Y, Preinfalk C, Gatter I, Strieder AJ (2003) Genesis of amethyst geodes in basaltic rocks of the Serra Geral Formation (Ametista do Sul, Rio Grande do Sul, Brazil): a fluid inclusion, REE, oxygen, carbon, and Sr isotope study on basalt, quartz, and calcite. Miner Depos 38:1009–1025

    Article  Google Scholar 

  • Goldberg K, Garcia AJV (2000) Palaeobiogeography of the Bauru Group, a dinosaur-bearing Cretaceous unit, northeastern Paraná basin, Brazil. Cretaceous Res 21:241–254

    Article  Google Scholar 

  • Goldstein RH, Reynolds TJ (1994) Systematics of fluid inclusions in diagenetic minerals. SEPM Short Course 31:1–199

    Google Scholar 

  • Gonfiantini R, Fontes JC (1963) Oxygen isotope fractionation in the water of crystallization of gypsum. Nature 200:644–646

    Article  Google Scholar 

  • Götze J, Plötze M, Fuchs H, Habermann D (1999) Defect structure and luminescence behaviour of agate—results of electron paramagnetic resonance (EPR) and cathodoluminescence (CL) studies. Miner Mag 63:149–163

    Article  Google Scholar 

  • Hardie LD (1967) The gypsum-anhydrite equilibrium at one atmosphere pressure. Am Mineral 52:171–200

    Google Scholar 

  • Hartmann LA, Wildner W, Duarte LC, Duarte SK, Pertille J, Arena KR, Martins LC, Dias NL (2010) Geochemical and scintillometric characterization and correlation of amethyst-bearing Paraná lavas from the Quaraí and Los Catalanes districts, Brazil and Uruguay. Geol Mag 147:954–970

    Article  Google Scholar 

  • Hartmann LA, Duarte LC, Massonne HJ, Michelin C, Rosenstengel LM, Bergmann M, Theye T, Pertille J, Arena KR, Duarte SK, Pinto VM, Barboza EG, Rosa MLCC, Wildner W (2012a) Sequential opening and filling of cavities forming vesicles, amygdales and giant amethyst geodes in lavas from the southern Paraná volcanic province, Brazil and Uruguay. Int Geol Rev 54:1–14

    Article  Google Scholar 

  • Hartmann LA, Medeiros JTN, Petruzzellis LT (2012b) Numerical simulations of amethyst geode cavity formation by ballooning of altered Paraná volcanic rocks, South America. Geofluids 12:133–141

    Article  Google Scholar 

  • Hofmann BA, Farmer JD, von Blankenburg F, Fallick AE (2008) Subsurface filamentous fabrics: an evaluation of origins based on morphological and geochemical criteria, with implications for exopaleontology. Astrobiology 8:87–117

  • International Critical Tables of Numerical Data, Physics, Chemistry and Technology, vol. III, McGraw-Hill, New York, 1928

  • Juchem PL (1999) Mineralogia, geologia e gênese dos depósitos de Ametista da região do Alto Uruguai, Rio Grande do Sul. PhD thesis, Universidade de São Paulo, Brazil

  • Juchem PL, Hartmann LA, Massonne HJ, Theye T (2009) Oxygen isotope composition of amethyst and related silica minerals in volcanic rocks from the Paraná province, southern Brazil. Congr Bras Geochímica, Ouro Preto, p 6

    Google Scholar 

  • Kimmelmann e Silva AA, Rebouças AC, Santiago MMF (1989) 14C analyses of groundwater from the Botucatu aquifer system in Brazil. Radiocarbon 31:926–933

    Google Scholar 

  • Kimmelmann AA, Forster M, Coelho R (1995) Environmental isotope and hydrogeochemical investigation of Bauru and Botucatu aquifers, Paraná Basin, Brazil. In: Isotope Hydrology Investigations in Latin America, IAEA, Vienna, IAEA-TECDOC-835, pp. 57–74

  • Krüger Y, Stoller P, Rička J, Frenz M (2007) Femtosecond lasers in fluid inclusion analysis: overcoming metastable phase states. European J Mineral 19:693–706

    Article  Google Scholar 

  • Lieber W (1985) Pseudomorphose von Quarz nach Anhydrit. Der Aufschluss 36:143–144

    Google Scholar 

  • Machel HG, Krouse HR, Sassen R (1995) Products and distinguishing criteria of bacterial and thermochemical sulfate reduction. Applied Geochem 10:373–389

    Article  Google Scholar 

  • Mao S, Duan Z (2008) The P, V, T, x properties of binary aqueous chloride solutions up to T = 573 K and 100 MPa. J Chem Thermodynamics 40:1046–1063

    Article  Google Scholar 

  • Mariani P, Braitenberg C, Ussami N (2013) Explaining the thick crust in Paraná basin, Brazil, with satellite GOCE gravity observations. J South American Earth Sci 45:209–223

    Article  Google Scholar 

  • Marti D, Krüger Y, Frenz M (2009) Fluid inclusion liquid-vapour homogenization in the vicinity of the density maximum of aqueous solutions. ECROFI XX Abstract

  • Marti D, Krüger Y, Frenz M, Rička J (2012) The effect of surface tension on liquid–gas equilibria in isochoric systems and its application to fluid inclusions. Fluid Phase Equilibria 314:13–21

    Article  Google Scholar 

  • Matsuhisa Y, Goldsmith JR, Clayton RN (1978) Oxygen isotope fractionations in the system quartz-anorthite-water. Geochim Cosmochim Acta 42:1131–1140

    Google Scholar 

  • Matsui E, Salati E, Marini OJ (1974) D/H and 18O/16O ratios in waters contained in geodes from the Basaltic Province of Rio Grande do Sul, Brazil. Geol Soc Am Bull 85:577–580

    Article  Google Scholar 

  • McKinley JP, Stevens TO, Westall F (2000) Microfossils and paleoenvironments in deep subsurface basalt samples. Geomicrobiology 17:43–54

    Article  Google Scholar 

  • McMillan K, Cross RW, Long PE (1987) Two-stage vesiculation in the Cohassett flow of the Grande Ronde Basalt, south-central Washington. Geology 15:809–812

    Article  Google Scholar 

  • Meng SX, Maynard JB (2001) Use of statistical analysis to formulate conceptual models of geochemical behavior: water chemical data from the Botucatu aquifer in São Paolo state, Brazil. J Hydrol 250:78–97

    Article  Google Scholar 

  • Meunier A, Formoso MLL, Patrier P, Chies JO (1988) Altération hydrothermale de roches volcaniques liée à la genèse des améthystes - Bassin du Paraná - sud do Brésil. Geochim Brasiliensis 2:127–142

    Google Scholar 

  • Montaño J, Tujchneider O, Auge M, Fili M, Paris M, D’Elía M, Pérez M, Nagy MI, Collazo P, Decoud P (1998) Acuíferos Regionales en América Latina. Sistema Acuífero Guaraní. Capítulo argentino-uruguayo. Centro de Publicationes Universidad Nacional del Litoral, Santa Fe, Argentina, p 216

    Google Scholar 

  • Morteani G, Kostitsyn Y, Preinfalk C, Gilg HA (2010) The genesis of the amethyst geodes at Artigas (Uruguay) and the paleohydrology of the Guaraní aquifer: structural, geochemical, oxygen, carbon, strontium isotope and fluid inclusion study. Intern J Geol Sci 99:927–947

    Google Scholar 

  • Moxon T, Petrone CM, Reed SJB (2013) Characterization and genesis of horizontal banding in Brazilian agate: an X-ray diffraction, thermogravimetric and electron microprobe study. Miner Mag 77:227–248

    Article  Google Scholar 

  • Müller A (2000) Cathodoluminescence and characterization of defect structures in quartz with applications to the study of granitic rocks. PhD thesis, University of Göttingen, pp. 1-222

  • Neuser RD, Bruhn F, Götze J, Habermann D, Richter DK (1995) Kathodolumineszenz: Methodik und Anwendung. Zbl Geol Paläont Teil I, H 1/2:287–306

    Google Scholar 

  • O’Neil JR, Epstein S (1966) A method for oxygen isotope analysis of milligram quantities of water and some of its applications. J Geophys Res 71:4955–4961

    Article  Google Scholar 

  • Ohmoto H, Goldhaber MB (1997) Sulfur and carbon isotopes. In: Barnes HL (ed) Geochemistry of hydrothermal ore deposits, 3rd edn. John Wiley & Sons, New York, pp 517–611

    Google Scholar 

  • Pesce A (2002) Thermal spas: an economic development alternative along both sides of the Uruguay river. GHC Quart Bull Geo, Heat Center Campus Drive, September 2002, pp 22–28

  • Pinto VM, Hartmann LA, Santos JOS, McNaughton NJ, Wildner W (2011) Zircon U–Pb geochronology from the Paraná bimodal volcanic province support a brief eruptive cycle at ~135 Ma. Chem Geol 281:93–102

    Article  Google Scholar 

  • Pöllmann H (2010) Kugelfluorit auf Amethyst aus Rio Grande do Sul/Brasilien. Der Aufschluss 61:321–323

    Google Scholar 

  • Proust D, Fontaine C (2007a) Amethyst-bearing lava flows in the Paraná Basin (Rio Grande do Sul, Brazil): cooling, vesiculation and formation of the geodic cavities. Geol Mag 144:53–65

    Article  Google Scholar 

  • Proust D, Fontaine C (2007b) Amethyst geodes in the basaltic flow from Triz quarry at Ametista do Sul (Rio Grande do Sul, Brazil): magmatic source of silica for the amethyst crystallizations. Geol Mag 144:731–740

    Article  Google Scholar 

  • Rosenstengel LM, Hartmann LA (2012) Geochemical stratigraphy of lavas and fault-block structures in the Ametista do Sul geode mining district, Paraná volcanic province, southern Brazil. Ore Geol Rev 48:332–348

    Article  Google Scholar 

  • Rossman GR (1994) Colored varieties of the silica minerals. Rev Mineral 29:433–467

    Google Scholar 

  • Sharp ZD (1990) A laser-based microanalytical method for the in situ determination of oxygen isotope ratios of silicates and oxides. Geochim Cosmochim Acta 54:1353–1357

    Article  Google Scholar 

  • Sharp ZD, Kirschner DL (1994) Quartz-calcite oxygen isotope thermometry; a calibration based on natural isotopic variations. Geochim Cosmochim Acta 58:4491–4501

    Article  Google Scholar 

  • Silva RBG (1983) Hydrogeochemical and isotopic study of groundwater of the Botucatu Aquifer, in São Paulo state (in Portuguese). PhD thesis, University of São Paulo, Brazil

  • Sracek O, Hirata R (2002) Geochemical and stable isotopic evolution of the Guaraní acquifer system in the State of São Paulo, Brazil. Hydrogeol J 10:643–655

    Article  Google Scholar 

  • Stevens TO, McKinley JP (1995) Lithoautotrophic microbia, ecosystems in deep basalt aquifers. Science 270:450–454

    Article  Google Scholar 

  • Stevens TO, McKinley JP, Fredrickson JK (1993) Bacteria associated with deep, alkaline, anaerobic groundwaters in southeast Washington. Microb Ecol 25:35–50

    Article  Google Scholar 

  • Stewart K, Turner S, Kelley S, Hawkesworth CJ, Kirstein L, Mantovani M (1996) 3-D, 40Ar-39Ar geochronology in the Paraná continental flood basalt province. Earth Planet Sci Lett 143:95–109

    Article  Google Scholar 

  • Thiede DS, Vasconcelos PM (2010) Paraná flood basalts: rapid extrusion hypothesis confirmed by new 40Ar/39Ar results. Geology 38:747–750

    Article  Google Scholar 

  • Thordarson T, Self S (1998) The Roza Member, Columbia River Basalt Group: a gigantic pahoehoe lava flow field formed by endogenous processes? J Geophys Res 103:27,411–27,445

    Article  Google Scholar 

  • Thordarson T, Sigmarsson O (2009) Effusive activity in the 1963–1967 Surtsey eruption, Iceland: flow emplacement and growth of small lava shields. In: Thordarson T, Self S, Larsen G, Rowland SK, Hoskuldsson A (eds) Studies in volcanology: the legacy of George Walker. Special Publications of IAVCEI 2, Geological Society, London, pp 53–84

    Google Scholar 

  • Turner S, Relegous M, Hawkesworth CJ, Mantovani M (1994) Magmatism and continental break-up in the South Atlantic: high precision 40Ar-39Ar geochronology. Earth Planet Sci Lett 121:333–348

    Article  Google Scholar 

  • Vasconcelos PM (1998) 40Ar/39Ar dating of celadonite and the formation of amethyst geodes in the Paraná Continental Flood Basalt Province. AGU 1998 fall meeting, San Francisco, F933 (abs)

  • Wagner W, Pruß A (2002) The IAPWS formulation 1995 for the thermodynamic properties of ordinary water substance for general and scientific use. J Phys Chem Ref Data 31:387–535

    Article  Google Scholar 

  • Wright R (1919) The effect of some simple electrolytes on the temperature of maximum density of water. J Chem Soc 115:119–126

    Article  Google Scholar 

  • Zalan PV, Wolf S, Astolfi MAM, Vieira IS, Conceição JC, Appi VT, Santos Neto EV, Cerqueira JR, Marques A (1991) The Paraná Basin, Brazil. In: Leighton MW, Kolata DR, Oltz DF, Eidel JJ (eds) Interior cratonic basins. AAPG Memoir 51, pp. 681–708

Download references

Acknowledgments

The authors thank Dr. N. Scherrer from HKB (Bern, Switzerland) for providing access to the Raman facility and for assisting with the measurements. We also appreciate the discussions with Dr. D. Marti (IAP, University of Bern, Switzerland) and his assistance with the interpretation of the T h -T hr measurements. B. Steinhilber and G. Stoschek for assistance during hydrogen, oxygen and sulphur isotope measurements. The constructive and careful reviews by B. Lehmann and U. Hein are greatly acknowledged. This study was partly funded by Swiss National Science Foundation (SNSF grant no. 200021-119966).

Author information

Authors and Affiliations

  1. Lehrstuhl für Ingenieurgeologie, TUM, Arcisstr. 21, 80333, Munich, Germany

    H. Albert Gilg

  2. Institut für Angewandte Physik, Universität Bern, Sidlerstrasse 5, 3012, Bern, Switzerland

    Yves Krüger & Martin Frenz

  3. Lehrstuhl für Isotopengeochemie, Universität Tübingen, Wilhelmstrasse 56, 72074, Tübingen, Germany

    Heinrich Taubald

  4. Angewandt Geologie, Universität Göttingen, Goldschmidtstr. 3, 37077, Göttingen, Germany

    Alfons M. van den Kerkhof

  5. Hydroisotop GmbH, Woelkestrasse 9, 85301, Schweitenkirchen, Germany

    Giulio Morteani

Authors
  1. H. Albert Gilg
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yves Krüger
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Heinrich Taubald
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Alfons M. van den Kerkhof
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Martin Frenz
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Giulio Morteani
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to H. Albert Gilg.

Additional information

Editorial handling: B. Lehmann

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Gilg, H.A., Krüger, Y., Taubald, H. et al. Mineralisation of amethyst-bearing geodes in Ametista do Sul (Brazil) from low-temperature sedimentary brines: evidence from monophase liquid inclusions and stable isotopes. Miner Deposita 49, 861–877 (2014). https://doi.org/10.1007/s00126-014-0522-7

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00126-014-0522-7

Keywords

Search

Navigation