Abstract
Based on regular arrays in a U-Pb diagram of data points of zircons from polymetamorphic rocks of the Alps quantitative models are developed that include several episodic lead losses, continuous lead losses during discrete periods and combinations of both.
The data from the Alps can be explained by assuming an initial age of the zircons of 2000 and/or 2500–2600 m.y. and three episodic lead losses 520–580 m.y., 300 m.y. and 30 m.y. ago with regionally varying intensities of the events as can be seen from the efficiency parameters which define the shape of the discordia. On the other hand, zircon data from North American basement rocks satisfy a model assuming a discrete interval of continuous lead loss that starts with the time of uplift of the rocks.
The Th-U-Pb diagrams are valuable for recognising whether the history of the zircons and their host rock is a complex one or not which is not always noticeable in a U-Pb diagram.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Ahrens, L.: The convergent lead ages of the oldest monazites and uraninites. Geochim. Cosmochim. Acta7, 294–300 (1955)
Allègre, C. J.: Unpublished report (1965)
Allègre, C. J.: Méthode de discussion géochronologique concordia géneralisée. Earth Planet. Sci. Lett.2, 57–66 (1967)
Arnold, A.: On the history of the Gotthard massive. (Abstract). Eclogae Geol. Helv.63, 29–30 (1970)
Bearth, P.: In: Geologischer Führer der Schweiz, S. 346–348. Basel 1967
Bruggmann, H.: Geologie und Petrographie des südlichen Misox, Dissertation, Universität Zürich, 1965
Cadisch, J.: Geologie der Schweizer Alpen. Basel, 1953
Casasopra, S.: Studio petrografico dello Gneiss granitico Leventina. Schweiz. Mineral. Petrog. Mitt.19, 449–708 (1939)
Casasopra, S.: Brevi cenni sulla genesi del granito gneissico Leventina. Schweiz. Mineral. Petrog. Mitt.28, 127–139 (1948)
Catanzaro, E. J.: Zircon ages in southwestern Minnesota. J. Geophys. Res.68, 2045–2048 (1963)
Catanzaro, E. J., Kulp, J. L.: Discordant zircons from the Little Belt (Montana), Beartooth (Montana) and Santa Catalina (Arizona) Mountains. Geochim. Cosmochim. Acta28, 87–124 (1964)
Craig, H.: Zircon lead loss: a kinetic model, Science159, 447 (1968)
Damon, P. E.: Potassium-argon dating of igneous and metamorphic rocks with applications to the Basin ranges of Arizona and Sonora. In: Radiometric dating for geologists, eds. Hamilton, E. I. and Farquhar, R. M., p. 1–71. London 1968
Goldich, S. S., Hedge, C. E., Stern, T. W.: Age of the Morton and Montevideo Gneisses and Related Rocks, Southwestern Minnesota. Bull. Geol. Soc. Am.81, 3671–3695 (1970)
Grauert, B.: Rb-Sr age determinations on orthogneisses of the Silvretta (Switzerland). Earth Planet. Sci. Lett.1, 139–147 (1966)
Grauert, B., Arnold, A.: Deutung diskordanter Zirkonalter der Silvrettadecke und des Gotthardmassivs (Schweizer Alpen). Contr. Mineral. and Petrol.20, 34–56 (1968)
Gruenenfelder, M., Hanson, G. N., Brunner, G. O., Eberhard, E.: U-Pb discordance and phase unmixing in zircons. Bull. Geol. Soc. Am.77, 1202 (1966)
Gruenenfelder, M., Krebs, O., Soroiu, M., Popescu, G.: Radiometric dating in the southern branch of the Romanian Carpathians: U-Th-Pb and K-Ar ages of the Susita and Tismana granitoids. In press.
Günthert, A.: Beiträge zur Petrographie und Geologie des Maggia-Lappens. Schweiz. Mineral. Petrog. Mitt.34, 1–159 (1954)
Hamet, J., Albarède, F.: Rb-Sr geochronology of the Ceneri zone (Southern Alps). Fortschr. Mineral.50, Beiheft 3, 80–82 (1973)
Hart, S. R., Davis, G. L., Steiger, R. H., Tilton, G. R.: A comparison of the isotopic mineral age variations and petrologic changes induced by contact metamorphism. In: Radiometric dating for geologists, eds. Hamilton, E. I. and Farquhar, R. M., p. 73–110. London 1968
Hunziker, H. J.: Zur Geologie und Geochemie des Gebietes zwischen Valle Antigorio (Prov. di Novara) und Valli di Campo (Kt. Tessin). Schweiz. Mineral. Petrog. Mitt.46, 473–552 (1966)
Hunziker, J. C.: Polymetamorphism in the Monte Rosa, Western Alps. Eclogae Geol. Helv.63, 151–161 (1970)
Jäger, E., Niggli, E., Baethge, H.: Two standard minerals, biotite and muscovite, for Rb-Sr and K-Ar age determinations, sample Bern 4 B and Bern 4 M from a gneiss from Brione, Valle Verzasca (Switzerland). Schweiz. Mineral. Petrog. Mitt.43, 465–470 (1963)
Jaeger, E., Niggli, E., Wenk, E.: Rb-Sr Altersbestimmungen an Glimmern der Zentralalpen. Beitr. Geol. Karte Schweiz. NF 134 (1967)
Keller, F.: Mineralparagenesen und Geologie der Campo Tencia — Pizzo Forno — Gebirgsgruppe. Beitr. Geol. Karte Schweiz NF 135 (1968)
Kobe, H.: Geologisch-petrographische Untersuchungen in der Tessiner Wurzelzone zwischen Vergeletto-Onsernone und Valle Maggia. Schweiz. Mineral. Petrog. Mitt.36, 244–348 (1956)
Koeppel, V., Gruenenfelder, M.: A study of inherited and newly formed zircons from paragneisses and granitised sediments of the Strona-Ceneri zone (Southern Alps). Schweiz. Mineral. Petrog. Mitt.51, 387–411 (1971)
Koeppel, V.: Isotopic U-Pb ages of monazites and zircons from the crust-mantle transition and adjacent units of the Ivrea and Ceneri zones (Southern Alps, Italy). Contr. Mineral. and Petrol, (in press)
Koeppel, V., Sommerauer, J.: Trace elements and the behaviour of the U-Pb system in inherited and newly formed zircons. Contr. Mineral. and Petrol. (in press)
Krogh, T. E., Davis, G. L.: The Grenville front interpreted as an ancient plate boundary. Annual Report of the Director, Geophysical Laboratory, 239–240 (1971)
Kulp, J. L., Eckelmann, W. R.: Discordant U-Pb ages and mineral type. Am. Mineralogist42, 154–164 (1957)
McDowell, F. M.: Potassium-argon ages from the Ceneri zone, Southern Swiss Alps. Contr. Mineral. and Petrol.28, 165–182 (1970)
Milnes, A. G.: Structure and history of the Antigorio nappe (Simplon group, North Italy). Schweiz. Mineral. Petrog. Mitt.45, 167–177 (1965)
Naylor, R. S., Steiger, R. H., Wasserburg, G. J.: U-Th-Pb and Rb-Sr systematics in 2700×106 year old plutons from the Southern Wind River Range (Wyoming). Geochim. Cosmochim. Acta34, 1133–1159 (1970)
Niggli, E.: Alpine Metamorphose und alpine Gebirgsbildung. Fortschr. Mineral.47, 16–26 (1970)
Niggli, P., Preiswerk, H., Gruetter, O., Bosshard, L., Kuendig, R.: Geologische Beschreibung der Tessiner Alpen zwischen Maggia-und Bleniotal. Beitr. Geol. Karte Schweiz NF 71 (1936)
Pidgeon, R. T., Koeppel, V., Gruenenfelder, M.: U-Pb isotopic relationships in zircon suites from a para- and orthogneiss from the Ceneri zone, southern Switzerland. Contr. Mineral. and Petrol.26, 1–11 (1970)
Pidgeon, R. T., O'Neil, J. R., Silver, L. T.: Uranium and lead isotopic stability in a metamict zircon under experimental hydrothermal conditions. Science154, 1538–1540 (1966)
Silver, L. T.: The use of cogenetic uranium-lead isotope systems in zircons in geochronology. In: Radioactive Dating, Int. Atomic Energy Agency, Symp. Athens 1962, Proc., 279–287 (1963)
Silver, L. T., Deutsch, S.: Uranium-lead isotopic variations in zircons: a case study. J. Geol.71, 721–758 (1963)
Steiger, R. H., Baer, M. T., Buesch, W.: The zircon age of an anateetic rock in the central Black Forest. Fortschr. Mineral.50, Beiheft 3 (1972)
Steiger, R. H., Wasserburg, G. J.: Systematics in the208Pb-232Th,207Pb-235U and206Pb-238U systems. J. Geophys. Res.71, 6065–6090 (1966)
Steiger, R. H., Wasserburg, G. J.: Comparative U-Th-Pb systematics in 2.7×109 year plutons of different geologic histories. Geochim. Cosmochim. Acta33, 1213–1232 (1969)
Stern, T. W., Goldich, S. S., Newell, M. F.: Effects of weathering on the U-Pb ages of zircon from the Morton gneiss, Minnesota. Earth Planet. Sci. Lett.1, 369–371 (1966)
Stern, T. W., Phair, G., Newell, M. F.: Boulder Creek batholith, Colorado. Part II: Isotopic age of emplacement and morphology of zircon. Bull. Geol. Soc. Am.82, 1615–1634 (1971)
Streckeisen, A.: In: Geologischer Führer der Schweiz, S. 337–346. Basel 1967
Tilton, G. R.: Volume diffusion as a mechanism for discordant lead ages. J. Geophys. Res.65, 2933–2945 (1960)
Tilton, G. R., Wetherill, G. W., Davis, G. L., Hopson, C. A.: Ages of minerals from the Baltimore gneiss near Baltimore, Maryland. Bull. Geol. Soc. Am.69, 1469–1474 (1958)
Ulrych, T. J.: Discordant lead-uranium ages due to continuous loss of lead. Nature200, 561–562 (1963)
Vitrac, A., Allègre, C. J.: Datation87Rb-87Sr des gneiss du Canigou et de l'Agly (Pyrénées Orientales, France), Compt. Ren.273, 2411–2413 (1971)
Wasserburg, G. J.: Diffusion processes in lead-uranium systems. J. Geophys. Res.68, 4823–4846 (1963)
Wenk, E.: Ergebnisse und Probleme der Gefügeuntersuchungen im Verzascatal (Tessin). Schweiz. Mineral. Petrog. Mitt.23, 265–294 (1943)
Wenk, E.: In: Geologischer Führer der Schweiz, S. 348–350. Basel 1967
Wenk, E.: Zur Regionalmetamorphose und Ultrametamorphose im Lepontin. Fortschr. Mineral.47, 34–51 (1970)
Wetherill, G. W.: Discordant uranium-lead ages. Trans. Geophys. Union37, 320–326 (1956)
Wetherill, G. W.: Discordant uranium-lead ages, part 2: discordant ages resulting from diffusion of lead and uranium. J. Geophys. Res.68, 2957–2965 (1963)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Allègre, C.J., Albarède, F., Grünenfelder, M. et al. 238U/206Pb-235U/207Pb-232Th/208Pb zircon geochronology in alpine and non-alpine environment. Contr. Mineral. and Petrol. 43, 163–194 (1974). https://doi.org/10.1007/BF01134835
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01134835