Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-22T15:47:27.920Z Has data issue: false hasContentIssue false
  • English
  • Français

Cobaltite-rich mineralization in the iron skarn deposit of Traversella (Western Alps, Italy)

Published online by Cambridge University Press:  05 July 2018

P. Nimis ,
L. Dalla Costa  and
A. Guastoni
P. Nimis*
Affiliation:
Dipartimento di Geoscienze, Università di Padova, via Gradenigo 6, 35131 Padua, Italy
L. Dalla Costa
Affiliation:
Amici Museo "G. Zannato", Piazza Marconi, 15, 36075 Montecchio Maggiore (VI), Italy
A. Guastoni
Affiliation:
Museo di Mineralogia, Università di Padova, via Giotto 1, 35121 Padua, Italy
*
*E-mail: paolo.nimis@unipd.it
Get access Rights & Permissions [Opens in a new window]

Abstract

Cobaltite-rich mineralization from the iron skarns of the Traversella magnetite mine (Western Alps, Italy) was studied by reflected-light microscopy, scanning electron microscopy and electron microprobe analysis. Cobaltite is found in carbonate-chlorite-rich rocks at the margins of the main magnetite masses, where it forms disseminations and metasomatic veinlets that postdate the formation of magnetite. The paragenesis includes cobaltite (± arsenopyrite), bismuthinite, pyrrhotite and/or pyrite, chalcopyrite, carbonates, talc, chlorite and native gold, and is indicative of a low-sulfidation environment. The sulfarsenides show oscillatory and sector zoning, which indicates disequilibrium during crystal growth. Compositional variations are mainly due to variations in the Co/Fe ratio of arsenopyrite and in either the Co/Fe or the Ni/(Fe + Co) ratios of the coexisting cobaltite. The Ni contents are low to very low in the cobaltites (<2.4 wt.%) and very low in the arsenopyrites (<0.16 wt.%). The As/S molar ratios in the cobaltites are highly variable (0.59−1.00) and show a broad negative correlation with the Fe contents. The formation of cobaltite is related to circulation of relatively low-temperature (<∼300°C), (Co,As,Bi)-rich fluids during the retrograde sulfidation stage which followed the formation of magnetite. The apparent restriction of cobaltite (+ bismuthinite ± arsenopyrite) to the margins of the main magnetite columns may reflect the establishment of thermochemical gradients around the main direction of infiltration of the retrograde metasomatic fluids.

Keywords

cobaltiteskarnmagnetiteore depositsTraversellaWestern Alps
Type
Research Article
Information
Mineralogical Magazine , Volume 78 , Issue 1 , February 2014 , pp. 11 - 27
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2014

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

Babist, J., Handy, M.R., Konrad-Schmolke, M. and Hammerschmidt, K. (2006) Precollisional, multistage exhumation of subducted continental crust: The Sesia Zone, western Alps. Tectonics, 25, TC6008, doi:10.1029/2005TC001927, 25 pp.Google Scholar
Barkov, A.Y., Thibault, Y., Laajoki, K.V.O., Melezhik, V.A. and Nilsson, L.P. (1999) Zoning and substitutions in Co−Ni−(Fe)−PGE sulfarsenides from the Mount General’skaya layered intrusion, Artic Russia. The Canadian Mineralogist, 37, 127–142.Google Scholar
Barton, P.B. Jr. and Skinner, B.J. (1979) Sulfide mineral stabilities. Pp. 278–403 in: Geochemistry of Hydrothermal Ore Deposits (H.L. Barnes, editor). Wiley Interscience, New York.Google Scholar
Becker, M., De Villiers, J. and Bradshaw, D. (2010) The mineralogy and crystallography of pyrrhotite from selected nickel and PGE ore deposits. Economic Geology, 105, 1025–1037.Google Scholar
Berger, A., Thomsen, T.B., Ovtcharova, M., Kapferer, N. and Mercolli, I. (2012) Dating emplacement and evolution of the orogenic magmatism in the internal Western Alps: 1. The Miagliano Pluton. Swiss Journal of Geosciences, 105, 49–65.CrossRefGoogle Scholar
Béziat, D., Monchoux, P. and Tollon, F. (1996) Cobaltite–gersdorffite solid solution as a primary magmatic phase in spessartite, Lacaune area, Montagne Noire, France. The Canadian Mineralogist, 34, 503–512.Google Scholar
Bigioggero, B., Colombo, A., Del Moro, A., Gregnanin, A., Macera, P. and Tunesi, A. (1994) The Oligocene Valle del Cervo Pluton: an example of shoshonitic magmatism in the Western Italian Alps. Memorie della Società Geologica Italiana, 46, 409–421.Google Scholar
Bistacchi, A., Dal Piaz, G.V., Massironi, M., Zattin, M. and Balestrieri, M.L. (2001) The Aosta–Ranzola extensional fault system and Oligocene–Present evolution of the Austroalpine–Penninic wedge in the northwestern Alps. International Journal of Earth Sciences, 90, 654–667.CrossRefGoogle Scholar
Bottino, G., Mastrangelo, F., Natale, P. and Zucchetti, S. (1975) Minerali di ferro, manganese, nichelio e cobalto. Alpi Occidentali. Pp. 6–11 in: Memoria Illustrativa della Carta Mineraria d’Italia, scala 1:1.000.000 (G. Castaldo and G. Stampanoni, editors). Memorie della Carta Geologica d’Italia, XIV. Ministero dell’Industria del Commercio e dell’Artigianato, Servizio Geologico d’Italia.Google Scholar
Burke, E.A.J. and Zakrzewsky, M.A. (1983) A cobaltbearing sulphide–arsenide assemblage from the Nord Mine (Finnshytteberg), Sweden: a new occurrence of clinosafflorite. The Canadian Mineralogist, 21, 129–136.Google Scholar
Callegari, E., Cigolini, C., Medeot, O. and D’Antonio, M. (2004) Petrogenesis of calc-alkaline and shoshonitic post-collisional Oligocene volcanics of the Cover Series of the Sesia-Lanzo Zone, Western Italian Alps. Geodinamica Acta, 17, 1–29.CrossRefGoogle Scholar
Chessex, R. (1962) Détermination d’âge de quelques roches des Alpes du Sud par la “méthode des dommages dus à la radioactivité”. Schweizerische Mineralogische und Petrographische Mitteilungen, 42, 652–654.Google Scholar
Choi, S.-G. and Youm, S.-J. (2000) Compositional variation of arsenopyrite and fluid evolution at the Ulsan deposit, southeastern Korea: a low-sulfidation porphyry system. The Canadian Mineralogist, 38, 567–583.CrossRefGoogle Scholar
Ciobanu, C.L., Cook, N.J., Damian, F. and Damian, G. (2006) Gold scavenged by bismuth melts: An example from Alpine shear-remobilizates in the Highis– Massif, Romania. Mineralogy and Petrology, 87, 351–384.CrossRefGoogle Scholar
Clarke, D.E. (1969) Geology of the Mount Biggenden gold and bismuth mine and environs. Geological Survey of Queensland, Report no. 32, Queensland Department of Mines, 16 pp.Google Scholar
Compagnoni, R., Dal Piaz, G.V., Hunziker, J.C., Gosso, G., Lombardo, B. and Williams, P.F. (1977) The Sesia-Lanzo Zone: a slice of continental crust, with alpine HP-LT assemblages in the Western Italian Alps. Rendiconti della Società Italiana di Mineralogia e Petrologia, 33, 281–334.Google Scholar
Cook, N.J. and Ciobanu, C.L. (2001) Paragenesis of Cu- Fe ores from Ocna de Fier-Dognecea (Romania), typifying fluid plume mineralisation in a proximal skarn setting. Mineralogical Magazine, 65, 351–372.Google Scholar
Dal Piaz, G.V., Venturelli, G. and Scolari, A. (1979) Calc-alkaline to ultrapotassic postcollisional volcanic activity in the internal northwestern Alps. Memorie della Società Geologica Italiana, 32, 1–16.Google Scholar
Dobbe, R.T.M. and Oen, I.S. (1994) The polymetallic Cu-Co ores in the central mineralized zone at Tunaberg, Bergslagen, Sweden. Neues Jahrbuch für Mineralogie Abhandlungen, 166, 261–294.Google Scholar
Dubru, M., Vander Auwera, J., Van Merke De Lummen, G. and Verkaeren, J. (1988) Distribution of scheelite in magnesian skarns at Traversella (Piemontese Alps, Italy) and Costabonne (Eastern Pyrenees, France): Nature of associated magmatism and influence of fluid composition. Pp. 117–134 in: Mineral Deposits within the European Community (J. Boissonas and P. Omenetto, editors). Society of Geologists Applied to Mineral Deposits, Special Publication.Google Scholar
Einaudi, M.T. and Burt, D.M. (1982) Introduction – Terminology, classification and composition of skarn deposits. Economic Geology, 77, 745–754.CrossRefGoogle Scholar
Fanlo, I., Subias, I., Gervilla, F., Paniagua, A. and Garcìa, B. (2004) The composition of Co−Ni−Fe sulfarsenides, diarsenides and triarsenides from the San Juan de Plan deposit, Central Pyrenees, Spain. The Canadian Mineralogist, 42, 1221–1240.CrossRefGoogle Scholar
Fershtater, G.B. (1990) Empirical hornblende-plagioclase geobarometer. Geokhimiya, 3, 328–335.Google Scholar
Gastaldi, B. (1871) Studi geologici sulle Alpi Occidentali. Parte I, Memorie del Regio Comitato Geologico d’Italia, 1, 1–47.Google Scholar
Gruppo Mineralogico, Valchiusella, Pagano, R. and Barresi, A. (2005) La miniera di Traversella: passato, presente e futuro. Rivista Mineralogica Italiana, 1/2005, 8–26.Google Scholar
Hem, S.R. and Makovicky, E. (2004a) The system Fe−Co−Ni−As−S. I. Phase relations in the (Fe,Co,Ni)As0.5S1.5 section at 650° and 500 °C. The Canadian Mineralogist, 42, 43–62.Google Scholar
Hem, S.R. and Makovicky, E. (2004b) The system Fe−Co−Ni−As−S. II. Phase relations in the (Fe,Co,Ni)As1.5S0.5 section at 650° and 500°C. The Canadian Mineralogist, 42, 63–86.CrossRefGoogle Scholar
Hem, S.R., Makovicky, E. and Gervilla, F. (2001) Compositional trends in Fe, Co and Ni sulfarsenides and their crystalchemical implications; results from the Arroyo de la Cueva deposits, Ronda Peridotite, southern Spain. The Canadian Mineralogist, 39, 831–853.CrossRefGoogle Scholar
Hickey, R.J. III (1992) The Buckhorn Mountain (Crown Jewel) gold skarn deposit, Okanogan County, Washington. Economic Geology, 87, 125–141.CrossRefGoogle Scholar
Kapferer, N., Mercolli, I., Berger, A., Ovtcharova, M. and Fügenschuh, B. (2012) Dating emplacement and evolution of the orogenic magmatism in the internal Western Alps: 2. The Biella Volcanic Suite. Swiss Journal of Geosciences, 105, 67–84.CrossRefGoogle Scholar
Kerestedjian, T. (1997) Chemical and morphological features of arsenopyrite, concerning its use as a geothermometer. Mineralogy and Petrology, 60, 231–243.CrossRefGoogle Scholar
Klemm, D. (1965) Synthesen und Analysen in den Dreiecksdiagrammen FeAsS−CoAsS−NiAsS und FeS2−CoS2−NiS2 . Neues Jahrbuch für Mineralogie Abhandlungen, 103, 205–255.Google Scholar
Kontny, A., De Wall, H., Sharp, T.G. and Pósfai, M. (2000) Mineralogy and magnetic behavior of pyrrhotite from a 260°C section at the KTB drilling site, Germany. American Mineralogist, 85, 1416–1427.CrossRefGoogle Scholar
Kretschmar, U. and Scott, S.D. (1976) Phase relations involving arsenopyrite in the system Fe-As-S and their application. The Canadian Mineralogist, 14, 364–386.Google Scholar
Krummenacher, D. and Evernden, J. (1960) Détermination d’âge isotopique sur quelques roches des Alpes par la method K−Ar. Schweizerische Mineralogische und Petrographische Mitteilungen, 40, 267–277.Google Scholar
Laznicka, P. (2010) Giant Metallic Deposits. Springer, Heidelberg Dordrecht London New York, 949 p.CrossRefGoogle Scholar
Lusk, J. and Bray, D.M. (2002) Phase relations and the electrochemical determination of sulfur fugacity for selected reactions in the Cu−Fe−S and Fe−S systems at 1 bar and temperatures between 185 and 460 °C. Chemical Geology, 192, 227–248.CrossRefGoogle Scholar
Mattirolo, E., Novarese, V., Franchi, S., Stella, A., Cozzolino, F., Morganti, E. and Geronzi, A. (1959) Carta Geologica d’Italia, 1:100.000, Foglio 42, Ivrea, Servizio Geologico d’Italia.Google Scholar
Meinert, L.D., Dipple, G.M. and Nicolescu, S. (2005) World skarn deposits. Economic Geology, 100th Anniversary Volume, 299–336.CrossRefGoogle Scholar
Mueller, A.G., Lawrance, L.M., Muhling, J. and Pooley, G.D. (2012) Mineralogy and PTX relationships of the Archean Hannan South Au-Cu (Co-Bi) deposit, Kalgoorlie, Western Australia: Thermodynamic constraints on the formation of a zoned intrusionrelated skarn. Economic Geology, 107, 1–24.CrossRefGoogle Scholar
Müller, F. (1912) Die Erzlagerstätten von Traversella im Piemont, Italien. Zeitschrift für Praktische Geologie, 20, 209–240.Google Scholar
Nimis, P., Zaykov, V.V., Omenetto, P., Melekesteva, I.Yu., Tesalina, S.G. and Orgeval, J.J. (2008) Peculiarities of some mafic-ultramafic and ultramafic- hosted massive sulfide deposits from the Main Uralian Fault Zone, southern Urals. Ore Geology Reviews, 33, 49–69.CrossRefGoogle Scholar
Petruk, W. (1971) Mineralogical characteristics of the deposits and textures of the ore minerals. Pp. 108–139 in: The silver-arsenide deposits of the Cobalt-Gowganda region, Ontario (L.G. Berry, editor). The Canadian Mineralogist, 11.Google Scholar
Ray, G.E. (1995) Fe Skarns. Pp. 63–65 in: Selected British Columbia Mineral Deposit Profiles, Volume 1 – Metallics and Coal (D.V. Lefebure and G.E. Ray, editors). British Columbia Ministry of Employment and Investment, Open File 1995-20.Google Scholar
Rosenberg, C.L. (2004) Shear zones and magma ascent: A model based on a review of the Tertiary magmatism in the Alps. Tectonics, 23, TC3002, doi:10.1029/2003TC001526.CrossRefGoogle Scholar
Rossetti, P., Agangi, A., Castelli, D., Padoan, M. and Ruffini, R. (2007) The Oligocene Biella pluton (western Alps, Italy): new insights on the magmatic vs. hydrothermal activity in the Valsessera roof zone. Periodico di Mineralogia, 76, 223–240.Google Scholar
Stella, A. (1894) Relazione sul rilevamento eseguito nell’anno 1893 nelle Alpi Occidentali (Valli dell’Orco e della Soana), Bollettino del Regio Comitato Geologico d’Italia, 25, 343–371.Google Scholar
Sundblad, K., Zachrisson, E., Smeds, S.-A., Berglund, S. and Ålinder, C. (1984) Sphalerite geobarometry and arsenopyrite geothermometry applied to metamorphosed sulfide ores in the Swedish Caledonides. Economic Geology, 79, 1660–1668.CrossRefGoogle Scholar
Törmänen, T.O. and Koski, R.A. (2005) Gold enrichment and the Bi-Au association in pyrrhotite-rich massive sulfide deposits, Escanaba Trough, Southern Gorda Ridge. Economic Geology, 100, 1135–1150.CrossRefGoogle Scholar
Uglow, W.L. and Osborne, F.F. (1926) A gold-cobaltitelodestone deposit, British Columbia, with notes on the occurrence of cobaltite. Economic Geology, 21, 285–293.CrossRefGoogle Scholar
van Marcke de Lummen, G. and Vander Auwera, J. (1990) Petrogenesis of the Traversella diorite (Piemonte, Italy): a major trace element and isotopic (O, Sr) model. Lithos, 24, 121–136.CrossRefGoogle Scholar
Vander Auwera, J. (1988) Pétrologie et géochimie (terres rares, l8O/16O, 13C/12C, 87Sr/86Sr) des skarns ferrifères et tungstifères de Traversella (Ivrea, Italie). PhD Thesis, Université Catholique de Louvain, Belgium.Google Scholar
Vander Auwera, J. (1990) The porphyritic facies and the endoskarns of the Traversella monzodiorite: Implications for the evolution of the main intrusion (Ivrea, Italy). Schweizerische Mineralogische und Petrographische Mitteilungen, 70, 237–245.Google Scholar
Vander Auwera, J. and Andre, L. (1991) Trace element (REE) and isotopes (O, C, Sr) to characterize the metasomatic fluid source: evidence from the skarn deposit (Fe, W, Cu) of Traversella (Ivrea, Italy). Contributions to Mineralogy and Petrology, 106, 325–339.CrossRefGoogle Scholar
Vander Auwera, J. and Verkaeren, J. (1993) Occurrence of contrasting skarn formations in dolomites of the Traversella Deposit (Ivrea, Italy). Geologische Rundschau, 82, 726–740.CrossRefGoogle Scholar
Venerandi Pirri, I. (1986) Polymetallic Fe, Cu, Ni, As, Sb, Pb, Zn, Ag, U, Mo, W, paragenesis in the ore deposit of Traversella (Ivrea, NW Italy). Pp. 159–177 in: Mineral Parageneses (J.R. Craig, R.D. Hagni, W. Kiesl, I.M. Lange, N.V. Petrovskaya, T.N. Shadlun, G. Udubas–a and S.S. Augustithis, editors). Theophrastus Publications S.A., Athens, Greece.Google Scholar
Venturelli, G., Thorpe, S., Dal Piaz, G.V., Del Moro, A. and Potts, P.J. (1984) Petrogenesis of calc-alkaline, shoshonitic and associated ultrapotassic Oligocene volcanic rocks from the northwestern Alps, Italy. Contributions to Mineralogy and Petrology, 86, 209–220.CrossRefGoogle Scholar
Vielzeuf, D. (1983) The spinel and quartz association in high grade xenoliths from Tallante (SE Spain) and their potential use in geothermobarometry and barometry. Contributions to Mineralogy and Petrology, 82, 301–311.CrossRefGoogle Scholar
von Blanckenburg, F., Kagami, H., Deutsch, A., Oberli, F., Meier, M., Wiedenbeck, M., Barth, S. and Fischer, H. (1998) The origin of Alpine plutons along the Periadriatic Lineament. Schweizer ische Mineralogische und Petrographische Mitteilungen, 78, 55–66.Google Scholar
Wagner, T. and Lorenz, J. (2002) Mineralogy of complex Co−Ni−Bi vein mineralization, Bieber deposit, Spessart, Germany. Mineralogical Magazine, 66, 385–407.CrossRefGoogle Scholar
Wirth, R. (1985) Dehydration and thermal alteration of white mica (phengite) in the contact aureole of the Traversella Intrusion. Neues Jahrbuch für Mineralogie Abhandlungen, 152, 101–112.Google Scholar
Zanoni, D. (2010) Structural and petrographic analysis at the north-eastern margin of the Oligocene Traversella pluton (Internal Western Alps, Italy). Italian Journal of Geosciences (Bollettino della Società Geologica Italiana), 129, 51–68.Google Scholar
Zucchetti, S. (1961) Uranium-bearing bodies in the ore deposits of Traversella (Italy). Economic Geology, 56, 1469–1471.CrossRefGoogle Scholar
Zucchetti, S. (1966a) Studi sul giacimento di Traversella (Torino). Nuove osservazioni sulla mineralizzazione radioattiva. Pp. 335–339 in: Atti del Simposio Internazionale sui Giacimenti Minerari delle Alpi, 1–2. Regione Trentino-Alto Adige, Trento, Italy.Google Scholar
Zucchetti, S. (1966b) Studi sul giacimento di Traversella (Torino). I corpi mineralizzati a scheelite. Pp. 939–960 in: Atti del Simposio Internazionale sui Giacimenti Minerari delle Alpi, 3. Regione Trentino-Alto Adige, Trento, Italy.Google Scholar