In-situ U–Th–Pb geochronometry with submicron-scale resolution: low-voltage electron-beam dating of complexly zoned polygenetic uraninite microcrystals

Open access


Complexly zoned microcrystals of uraninite were encountered in orthogneiss from the central Tauern Window in Austria (K1 gneiss, Felbertal scheelite mine) and analysed in-situ for U, Th and Pb with state-of-the-art FE-SEM/EDX techniques. A three times finer spatial resolution was achieved using an acceleration voltage of 8 kV, compared to the classic 15–20 kV set-up of U–Th–total Pb electron microprobe dating. The lower voltage allows a spheroid of material with a diameter of only 0.3 µm to be selectively analysed. Careful tests on three uraninite reference materials show that the low-voltage method yields sufficient precision and accuracy for U–Th–total Pb uraninite dating, with errors on individual spot ages in the order of 10–30 Ma. By means of this innovative analysis technique, small-scale age zoning patterns could be resolved and dated in the uraninite microcrystals from the orthogneiss. Based on microstructures observed in backscattered electron images we interpret that an older uraninite generation in the rock, with a late Permian formation age (~260 Ma), was recycled two times through a coupled dissolution–reprecipitation process at ~210 Ma and at ~30 Ma. The younger dissolution–reprecipitation phase at ~30 Ma coincides with the Alpine regional metamorphism (lower amphibolite facies). The two older ages (~210 Ma and ~260 Ma) have been previously recognized in rocks from the Tauern Window by uraninite dating, but it is the first time here that both are recorded in the same rock and even the same uraninite grain. The present study shows that recrystallized accessory uraninite can provide a sensitive geological “hard disk” where several discrete thermal events of an area are stored. In addition, our work attests that the mineral uraninite has an unexpected geochronological robustness, even on the microcrystal scale.

Allaz J., Raschke M.B., Persson Ph.M. & Stern Ch.R. 2015: Age, petrochemistry, and origin of a REE-rich mineralization in the Longs Peak–St. Vrain batholith, near Jamestown, Colorado (U.S.A.). Am. Mineral. 100, 2123–2140.

Alexandre P. & Kyser T.K. 2005: Effects of cationic substitutions and alteration in uraninite, and implications for the dating of uranium deposits. Can. Mineral. 43, 3, 1005–1017.

Alexandre P., Peterson R. & Joy B. 2016: Sector Zoning In Uraninite. Can. Mineral. 53, 1–11.

Amelin Y. & Davis W.J. 2006: Isotopic analysis of lead in sub-nanogram quantities by TIMS using a 202Pb–205Pb spike. J. Anal. At. Spectrom. 21, 10, 1053–1061.

Bernhard F., Finger F., Schitter F., Berka R. & Schuster R. 1998: Electron microprobe ages of monazite and xenotime from the Austroalpine basement units of the Fischbacher Alpen, Styria, Austria. Mitt. Österreich. Mineral. Gesellschaft 143, 246–248.

Bowles J.F.W. 1990: Age dating of individual grains of uraninite in rocks from electron microprobe analyses. Chem. Geol. 83, 1–2, 47–53.

Chipley D., Polito P.A. & Kyser T.K. 2007: Measurement of U–Pb ages of uraninite and davidite by laser ablation-HR-ICP-MS. Am. Mineral. 92, 11–12, 1925–1935.

Cliff R.A., Oberli F., Meier M., Droop G.T.R. & Kelly M. 2015: Syn-metamorphic folding in the Tauern Window, Austria dated by Th–Pb ages from individual allanite porphyroblasts. J. Meta-morph. Geol. 33, 4, 427–435.

Cocherie A. & Legendre O. 2007: Potential minerals for determining U–Th–Pb chemical age using electron microprobe. Lithos 93, 3–4, 288–309.

Cross A., Jaireth S., Rapp R. & Armstrong R. 2011: Reconnaissance-style EPMA chemical U–Th–Pb dating of uraninite. Australian J. Earth Sci. 58, 6, 675–683.

Davis D.W., Krogh T.E. & Williams I.S. 2003: Historical Development of Zircon Geochronology. Rev. Mineral. Geochem. 53, 1, 145–181.

Decrée S., Deloule E., Putter T., Dewaele S., Mees F., Yans J. & Marignac C. 2011: SIMS U–Pb dating of uranium mineralization in the Katanga Copperbelt: Constraints for the geodynamic context. Ore Geol. Rev. 40, 1, 81–89.

Drouin D., Couture A.R., Joly D., Tastet X., Aimez V. & Gauvin R. 2007: “CASINO V2.42” — A fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users. Scanning 29, 92–101.

Eichhorn R., Loth G., Höll R., Finger F., Schermaier A. & Kennedy A. 2000: Multistage Variscan magmatism in the central Tauern Window (Austria) unveiled by U/Pb SHRIMP zircon data. Contrib. Mineral. Petrol. 139, 4, 418–435.

Eichhorn R., Schärer U. & Höll R. 1995: Age and evolution of scheelite-hosting rocks in the Felbertal deposit (Eastern Alps): U–Pb geochronology of zircon and titanite. Contrib. Mineral. Petrol. 119, 4, 377–386.

Fayek M., Kyser T.K. & Riciputi L.R. 2002: U and Pb Isotpe analysis of uranium minerals by ion microprobe and the geochronology of the McArthur River and Sue Zone uranium deposits, Saskatchewan, Canada. Can. Mineral. 40, 6, 1553–1570.

Finger F., Krenn E., Schulz B., Harlov D. & Schiller D. 2016: “Satellite monazites” in polymetamorphic basement rocks of the Alps: Their origin and petrological significance. Am. Mineral. 101, 5, 1094.

Finger F., Waitzinger M., Förster H.J., Kozlik M. & Raith J. 2017: Identification of discrete hydrothermal events in polymetamorphic basement rocks using high spatial resolution U–Th–Pb chemical dating of uraninite microcrystals. Geology 45, 991–994.

Förster H.J. 1999: The Chemical Composition of Uraninite in Variscan Granites of the Erzgebirge, Germany. Mineral. Mag. 63, 2, 239–252.

Förster H.J., Rhede D., Stein H.J., Romer R.L. & Tischendorf G. 2012: Paired uraninite and molybdenite dating of the Königshain granite: implications for the onset of late-Variscan magmatism in the Lausitz Block. Int. J. Earth Sci. (Geol. Rundsch.) 101, 57–67.

Frasl G. & Frank W. 1966: Einführung in die Geologie und Petrographie des Penninikums im Tauernfenster. Der Aufschluß, Spec. Issue 15, Heidelberg, 30–58.

Frei D. & Gerdes A. 2009: Precise and accurate in situ U–Pb dating of zircon with high sample throughput by automated LA-SF-ICPMS. Chem. Geol. 261, 3–4, 261–270.

Ge X., Qin M. & Fan G. 2014: Study and Application of Electron Probe Micro-analysis Dating for Uraninite. Acta Geologica Sinica — English Edition 88, s2, 1345–1346.

Geisler T. & Schleicher H. 2000: Improved U–Th–total Pb dating of zircons by electron microprobe using a simple new background modeling procedure and Ca as a chemical criterion of fluid-induced U–Th–Pb discordance in zircon. Chem. Geol. 163, 1–4, 269–285.

Harlov D.E., Wirth R. & Hetherington C.J. 2011: Fluid-mediated partial alteration of monazite: the role of coupled dissolution–reprecipitation in element redistribution and mass transfer. Contrib. Mineral. Petrol. 162, 329–348.

Holmes A. 1911: The Association of Lead with Uranium in Rock-Minerals, and Its Application to the Measurement of Geological Time. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 85, 578, 248–256.

Hurtado J.M., Chatterjee N., Ramezani J., Hodges K.V. & Bowring S.A. 2007: Electron Microprobe Chemical Dating of Uraninite as a Reconnaissance Tool for Leucogranite Geochronology. Nature Precedings, hdl:10101/npre.2007.655.1.

Jercinovic M.J. & Williams M.L. 2005: Analytical perils (and progress) in electron microprobe trace element analysis applied to geochronology: background acquisition, interferences, and beam irradiation effects. Am. Mineral. 90, 526–546.

Jercinovic M.J., Williams M.L., Allaz J. & Donovan J. 2012: Trace Analysis in EPMA. IOP Conf. Series: Materials Science and Engineering 32, 1–22.

Kebede T., Klotzli U., Kosler J. & Torbjorn S. 2005: Understanding the pre-Variscan and Variscan basement components of the central Tauern Window, Eastern Alps (Austria): constraints from single zircon U–Pb geochronology. Int. J. Earth Sci. 94, 336–353.

Keppler H. & Whyllie P.J. 1990: Role of fluids in transport and fractionation of uranium and thorium in magmatic processes. Nature 348, 531–533.

Kempe U. 2003: Precise electron microprobe age determination in altered uraninite: consequences on the intrusion age and the metallogenic significance of the Kirchberg granite (Erzgebirge, Germany). Contrib. Mineral. Petrol. 145, 1, 107–118.

Kober B. 1986: Whole-grain evaporation for 207Pb/206Pb-age-investigations on single zircons using a double-filament thermal ion source. Contrib. Mineral. Petrol. 93, 4, 482–490.

Kilburn M.R. & Wacey D. 2014: Nanoscale secondary ion mass spectrometry (NanoSIMS) as an analytical tool in the geosciences. In: Grice K (Ed.): Principles and Practice of Analytical Techniques in Geosciences. The Royal Society of Chemistry, 1–34.

Koike M., Ota Y., Sano Y., Takahata N. & Sugiura N. 2014: High-spatial resolution U–Pb dating of phosphate minerals in Martian meteorite Allan Hills 84001. Geochem. J. 48, 5, 423–431.

Kotzer T.G. & Kyser T.K. 1993: O, U, and Pb isotopic and chemical variations in uraninite; implications for determining the temporal and fluid history of ancient terrains. Am. Mineral. 78, 11–12, 1262–1274.

Kozlik M. & Raith J. 2016: Variscan metagranitoids in the central Tauern Window (Eastern Alps, Austria) and their role in the formation of the Felbertal scheelite deposit. Lithos 278, 303–320.

Kozlik M., Raith J.G. & Gerdes A. 2016: U–Pb, Lu–Hf and trace element characteristics of zircon from the Felbertal scheelite deposit (Austria): New constraints on timing and source of W mineralization. Chem. Geol. 421, 112–126.

Krogh T.E. 1982: Improved accuracy of U-Pb zircon ages by the creation of more concordant systems using an air abrasion technique. Geochim. Cosmochim. Acta 46, 4, 637–649.

Ludwig K.R. 2003: User’s manual for Isoplot 3.00: a geochronological toolkit for Microsoft Excel. Kenneth R. Ludwig, 1–74.

Mattinson J.M. 2005: Zircon U–Pb chemical abrasion (“CA-TIMS”) method: Combined annealing and multi-step partial dissolution analysis for improved precision and accuracy of zircon ages. Chem. Geol. 220, 1–2, 47–66.

Montel J.-M., Foret S., Veschambre M., Nicollet C. & Provost A. 1996: Electron microprobe dating of monazite. Chem. Geol. 131, 1, 37–53.

Montel J.M., Kato T., Enami M., Cocherie A., Finger F., Williams M. & Jercinovic M. 2017: Electron probe dating of monazite — the story. Chem. Geol. 484, 4–15.

Naemura K., Hirajima T. & Svojtka M. 2009: The Pressure–Temperature Path and the Origin of Phlogopite in Spinel–Garnet Peridotites from the Blanský Les Massif of the Moldanubian Zone, Czech Republic. J. Petrol. 50, 10, 1795–1827.

Paar W. & Koeppel V. 1978: The ‘pitchblende-nodule-assemblage’ of Mitterberg (Salzburg, Austria). Neues Jahrb. Mineral. Abh. 131, 3, 254–271.

Parslow G.R., Bandstaetter F., Kurat G. & Thomas D.J. 1985: Chemical ages and mobility of U and Th in anatectites of the Cree Lake zone, Saskatchewan. Can. Mineral. 23, 4, 543–551.

Pestal G., Hejl E., Braunstingl R. & Schuster R. 2009: Erläuterungen Geologische Karte von Salzburg 1:200,000. Geologische Bundesanstalt, Wien, 1–162.

Peiffert C., Nguyen Trung C. & Cuney M. 1996: Uranium in granitic magmas. Part II: experimental determination of uranium solubility and fluid-melt partition coefficients in the UO2-haplogranite-H2O-halides system at 720-770°C, 200 MPa. Geochim. Cosmochim. Acta 60, 1515–1529.

Putnis A. 2002: Mineral replacement reactions: from macroscopic observations to microscopic mechanisms. Mineral. Mag. 66, 689–708.

Pyle J.M., Spear F.S. & Wark D.A. 2002: Electron Microprobe Analysis of REE in Apatite, Monazite and Xenotime: Protocols and Pitfalls. Rev. Mineral. Geochem. 48, 1, 337–362.

Săbău G. 2012: Chemical U–Th–Pb geochronology: a precise explicit approximation of the age equation and associated errors. Geochronometria 39, 167–179.

Santosh M., Yokoyama K., Biju-Sekhar S. & Rogers J.J.W. 2003: Multiple Tectonothermal Events in the Granulite Blocks of Southern India Revealed from EPMA Dating: Implications on the History of Supercontinents. Gondwana Res. 6, 1, 29–63.

Schaltegger U., Schmitt A.K. & Horstwood M.S.A. 2015: U–Th–Pb zircon geochronology by ID-TIMS, SIMS, and laser ablation ICP-MS: Recipes, interpretations, and opportunities. Chem. Geol. 402, 89–110.

Scherrer N., Engi M., Gnos E., Jakob V. & Liechti A. 2000: Monazite analysis; from sample preparation to microprobe age dating and REE quantification. Schweiz. Mineralog. Petrograph. Mitt. 80, 1, 93–105.

Schmid S.M., Fügenschuh B., Kissling E. & Schuster R. 2004: Tectonic map and overall architecture of the Alpine orogen. Eclogae Geologicae Helvetiae 97, 1, 93–117.

Schmid S.M., Scharf A., Handy M.R. & Rosenberg C.L. 2013: The Tauern Window (Eastern Alps, Austria): a new tectonic map, with cross-sections and a tectonometamorphic synthesis. Swiss J. Geosci. 106, 1, 1–32.

Schoene B., Guex J., Bartolini A., Schaltegger U. & Blackburn T.J. 2010: Correlating the end-Triassic mass extinction and flood basalt volcanism at the 100 ka level. Geology 38, 5, 387–390.

Shahin H.A. 2014: Geochemical Characteristics and Chemical Electron Microprobe U–Pb–Th Dating of Pitchblende Mineralization from Gabal Gattar Younger Granite, North Eastern Desert, Egypt. Open Journal of Geology 4, 24–32.

Stern R.A., Fletcher I.R., Rasmussen B., McNaughton N.J. & Griffin B.J. 2005: Ion microprobe (NanoSIMS 50) Pb-isotope geochronology at <5 μm scale. Int. J. Mass Spectrom. 244, 2–3, 125–134.

Suzuki K., Adachi M. & Tanaka T. 1991: Middle precambrian provenance of Jurassic sandstone in the Mino Terrane, central Japan: Th–U-total Pb evidence from an electron microprobe monazite study. Sediment. Geol. 75, 1–2, 141–147.

Tropper P., Harlov D., Krenn E., Finger F., Rhede D. & Bernhard F. 2007: Zr-bearing minerals as indicators for the polymetamorphic evolution of the eastern, lower Austroalpine nappes (Stubenberg Granite contact aureole, Styria, Eastern Alps, Austria). Lithos 95, 1–2, 72–86.

Vesela P., Soellner F., Finger F. & Gerdes A. 2012: Magmato–sedimentary Carboniferous to Jurassic evolution of the western Tauern window, Eastern Alps (constraints from U–Pb zircon dating and geochemistry) (vol. 100, pg. 993, 2011). Int. J. Earth Sci. 101, 2, 603.

von Quadt A. 1992: U–Pb zircon and Sm–Nd geochronology of mafic and ultramafic rocks from the central part of the Tauern Window (eastern Alps). Contrib. Mineral. Petrol. 110, 1, 57–67.

Votyakov S.L., Khiller V.V., Shchapova Y.V. & Erokhin Y.V. 2013: Composition and chemical microprobe dating of U–Th-Bearing minerals. Part 2. Uraninite, thorite, thorianite, coffinite, and monazite from the Urals and Siberia. Geol. Ore Deposits 55, 7, 515–524.

Williams I.S. 1998: U–Th–Pb geochronology by ion microprobe. In: McKibben M.A., Shanks W.C., Ridley W.I. (Eds.): Applications of Microanalytical Techniques to Understanding Mineralizing Processes. Reviews in Economic Geology, Littleton, 1–35.

Williams M.L. & Jercinovic M.J. 2002: Microprobe monazite geochronology: putting absolute time into microstructural analysis. J. Struct. Geol. 24, 6–7, 1013–1028.

Yokoyama K., Shigeoka M., Goto A., Terada K., Hidaka H. & Tsutsumi Y. 2010: U–Th-total Pb ages of Uraninite and Thorite from Granititc Rocks in the Japanese Islands. Bull. Natl. Mus. Nat. Sci. 36, 7–18.

Geologica Carpathica

The Journal of Geological Institute of Slovak Academy of Sciences

Journal Information

IMPACT FACTOR 2017: 1.169
5-year IMPACT FACTOR: 1.431

CiteScore 2017: 1.26

SCImago Journal Rank (SJR) 2017: 0.551
Source Normalized Impact per Paper (SNIP) 2017: 0.836


All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 41 41 18
PDF Downloads 44 44 30