Hostname: page-component-586b7cd67f-l7hp2 Total loading time: 0 Render date: 2024-12-03T19:23:19.088Z Has data issue: false hasContentIssue false

The fluorite vein mineralization of the southern Alps: combined application of fluid inclusions and rare earth element (REE) distribution

Published online by Cambridge University Press:  05 July 2018

U. F. Hein
Affiliation:
FG Petrologie, Technische Universität Berlin, EB 310, Str. d. 17 Juni 135, D-1000 Berlin 12, Federal Republic of Germany
V. Lüders
Affiliation:
AG Geochemie, Bereich Kernchemie und Reaktor, Hahn-Meitner-Institut, Glienicker Str. 100, D-1000 Berlin, F.R.G.
P. Dulski
Affiliation:
AG Geochemie, Bereich Kernchemie und Reaktor, Hahn-Meitner-Institut, Glienicker Str. 100, D-1000 Berlin, F.R.G.

Abstract

The fluorite vein deposits of the Southern Alps (Northern Italy) exhibit similar geotectonic, paragenetic, and textural characteristics permitting useful comparison between their fluid inclusions and REE systematics. Due to differing post-crystallization deformation, primary fluid inclusions can only be observed in the northernmost deposit (Rabenstein/Corvara). Here, fluorite precipitated from highly saline H2O-NaCl-CaCl2 solutions containing appreciable H2S. During vein formation the fluids changed from low salinity (≈7 wt. % NaCl equiv.) and medium temperature (Th ≈ 230°C), corresponding to the precipitation of early quartz, towards high salinity (≈20 wt.% NaCl equiv.) and lower temperatures (Th ≈170°C during the deposition of late-stage fluorite. This was accompanied by an increase in Ca in solution.

REE distribution patterns for the northern deposits are very uniform suggesting a similar source, a large-scale homogeneous fluid system, and fluorite precipitation under reducing conditions. By comparison the southern deposits exhibit contrasting patterns documenting a more complex history, probably due to their remobilization from an earlier mineralization. None of the fluorites shows a ‘primary’ magmatic REE distribution pattern, thereby favouring a genetic model for fluorite mineralization involving the leaching of suitable rock units by formation waters.

Type
Near-surface and surficial environments
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1990

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.)

Footnotes

*

Present address: IGDL, Goldschmidtstr. 3, D-3400 Göttingen, F.R.G.

References

Bakos, F., Brondi, A. and Perna, G. (1972) The age of mineral deposits in the Permian volcanites of Trentino- Alto Adige (Northern Italy). Proc. 2nd ISMIDA. Geol. Razpr. Poroc. 15, 181-94.Google Scholar
Behr, H. J. and Gerler, J. (1987) Inclusions of Sedimentary Brines in Post-Variscan Mineralizations in the Federal Republic of Germany—A Study by Neutron Activation Analysis. Chem. Geol. 61, 65-77.CrossRefGoogle Scholar
Bianehi, A., Boni, A., Callegari, E., Casati, P., Cassinis, G., Comizzoli, G., Dal Piaz, G. B., Desio, A., Giuseppetti, G., Martina, E., Passeri, L. D., Sassi, F. P., Zanettin, B. and Zirpoli, G. (1971) Note illustrative della Carta Geologica d'ltalia, 1:100000, Foglio 34, Breno, 134 pp. Roma.Google Scholar
Bierlein, J. and Kay, W. (1953) Phase equilibrium properties of the system carbon dioxide-hydrogen sulfide. Ind. Eng. Chem. 45, 618-24.CrossRefGoogle Scholar
Bodnar, R. J. and Bethke, P. M. (1984) Systematics of stretching of fluid inclusions I: Fluorite and sphalerite at 1 atmosphere confining pressure. Econ. Geol. 79, 141-61.CrossRefGoogle Scholar
Borisenko, A. S. (1978) Study of the salt composition of solutions of gas-liquid inclusions in minerals by the cryometric method. Soviet Geol. Geophys. 18/8, 1119.Google Scholar
Crawford, M. L. (1981) Phase equilibria in aqueous fluid inclusions. In Short course in fluid inclusions: applications to petrology (Hollister, L. S. and Crawford, M. L., eds.), 75100, Calgary. Mineral. Assoc. Canada.Google Scholar
Doglioni, C. and Bosellini, A. (1987) Eoalpine and neoalpine tectonics in the Southern Alps. Geol. Rdsch. 76, 735-47.CrossRefGoogle Scholar
Ferrara, G. and Innocenti, F. (1974) Radiometric age evidences of a Triassic thermal event in the Southern Alps. Ibid. 63, 572-81.CrossRefGoogle Scholar
Gallitelli, P. and Simboli, G. (1971) Petrological and geochemical research on the rocks of Predazzo and Monzoui (North Italy). Verh. Geol. B. A. 1971/2, 326-43.Google Scholar
Haditsch, J. G. and Mostler, H. (1982) Late Variscan and early Alpine mineralization in the Eastern Alps. In Ore genesis—The state of the art (Amstutz, G. C., ed.), 582-9. Berlin-Heidelberg-New York (Springer).Google Scholar
Hein, U. F. (1986) Zur Geochemie des Fhiors im Nebengestein und Spurenelementfraktioniernng in Fluoriten der kalkalpinen Pb-Zn Lagersfiitten. Berliner geowiss. Abh. (A) 81, 119pp.Google Scholar
Hein, U. F. (1989) Spatial and temporal development of fluorite mineralizations in the Eastern and Southern Alps. TERRA abstracts 1, S14/8, 53.Google Scholar
Jebrak, M. (1985) Contribution à l'histoire naturelle des filons (F, Ba) du domain varisque francais et marocain. Essai de caractérisation structurale et géochimique des filons en extension et e. décrochement. Doc. BRGM 99/1, 510 pp.Google Scholar
Krahmann, M. (1906) Das Erz- und Flußspatvorkommen am Rabenstein im Sarntal (Südtirol). Zeit. prakt. Geol. 14, 8-10.Google Scholar
Liiders, V. (1988) Geochemische Untersuchungen an Erz- und Gangartmineralen des Harzes. Berliner geowiss. Abh. (A) 93, 74pp.Google Scholar
Möller, P. (1983) Lanthanoids as a geochemical probe and problems in lanthanoid geochemistry. Distribution of lanthanoids in non-magmatic phases. In Systematics and Properties of the Lanthanides (Shina, S. P., ed.), 561-616, Dordrecht (D. Reidel).CrossRefGoogle Scholar
Möller, P. and Muecke, G. K. (1984) Significance of europium anomalies in silicate melts and crystal-melt equilibria: a re-evaluation. Contrib. Mineral. Petrol. 87, 242-50.CrossRefGoogle Scholar
Omenetto, P. and Brigo, L. (1981) Paragenetic and geochemical characterization of the pre-Variscan and Variscan ores of the Italian Alps. Freib. Forsch.-H. C 364, 3354.Google Scholar
Perna, G. (ed.) (1964) L'industria mineraria nel Trento—Alto Adige. Economia Trentina 1-2, 4-5, C.C.I.A., 360 pp., Trento (Saturnia).Google Scholar
Perna, G. (1971) Giacimenti minerari. In Note illustrative della Carta geologica Italiana (Braga, G. et al., eds), 1:100 000, Foglio 22, Feltre, 124-30.Google Scholar
Sassi, F. P., Cavazzini, G., Visonà, D., Del Moro, A. (1985) Radiometric chronology in the Eastern Alps: results and problems. Rend. Soc. ltal. Mineral. Petrol. 40, 187-224.Google Scholar
Shepherd, T. J. and Scrivener, R. C. (1987) Role of basinal brines in the genesis of polymetallic vein deposits, Kit Hill-Gunnislake area, SW England. Proc. Ussher Soc. 491-7.Google Scholar
Sourirajan, S. and Kennedy, G. C. (1962) The system H2O-NaCl at elevated temperatures and pressures. Am. J. Sci. 260, 115-41.CrossRefGoogle Scholar
Thomas, R. (1982) Ergebnisse der thermobarogeochemischen Untersuchugen an hydrothermalen Fhiorit-Paradoxit-Quarz-Mineralisationen des Erzgebirges und des SW-Vogtlandes. Freib. Forsch.-H. C 374, 6377.Google Scholar
Touray, J.-C. and Guilhaumou, N. (1984) Characterization of H2S-bearing fluid inclusions. Bull. Mineral. 107, 181-8.Google Scholar
Waither, J. (1981) Fluide Einschlüsse im Apatit des Carbonatits vom Kaierstuhl (Oberrheingraben): Ein Beitrag zur Interpretation der Carbonatitgenese. Doktoral thesis, 195 pp. Universität Karlsruhe.Google Scholar
Yanatieva, O. K. (1946) Solubility polytherms in the systems CaCl2-MgCl2-H2O and CaCl2-NaCl-H2O. Zhurnl. Prikl. Khimii 19, 709-22.Google Scholar