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Assessing the origin of old apparent ages derived by Pb stepwise leaching of vein-hosted epidote from Mount Isa, northwest Queensland, Australia

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Abstract

Epidote metasomatism affected large areas of tholeiitic metabasalts of the ~1,780 Ma Eastern Creek Volcanics in the Western Fold Belt of the Proterozoic Mount Isa inlier. Hydrothermal epidote generally occurs in quartz veins parallel to or boudinaged within the dominant S2 fabrics which formed during the regional metamorphic peak at ~1,570 Ma associated with the Isan orogeny. Previously published stable isotopic and halogen data suggest that the fluids responsible for epidote formation are metamorphic in origin (with an evaporitic component). Application of the Pb stepwise leaching technique to the epidote does not separate radiogenic Pb4+ and common Pb2+, generating little spread in 206Pb/204Pb (between 16.0 and 30.5). The causes for this relatively low range are twofold: There is little radiogenic Pb in the epidotes (the most radiogenic steps account for <1 % of Pb released) and both Pb2+ and uranogenic Pb4+ substitute into the same site in the epidote crystal lattice. Consequently, age regressions using the Pb stepwise leaching data give ages between 150 and 1,500 myrs older than the host rocks and over 450 myrs older than the thermal metamorphic peak. These old ages are attributed to chemical inheritance from the host metabasalts, via radiogenic Pb release by breakdown of phases such as zircon, monazite, titanomagnetite, and ilmenite during metamorphism. This idea is supported by trace element data and chrondrite-normalized rare earth element patterns that are similar to both the metabasalts and epidotes (except for a variable Eu anomaly in the latter). Relatively high fO2 during vein formation (Fe3+ dominates in the epidote crystal lattice) would allow the incorporation of Th4+ and exclusion of U6+ and would explain elevated Th/U ratios (up to 12) in epidote compared with the host metabasalts. Non-incorporation of U would explain the relatively low U/Pb ratios and non-radiogenic character of the epidote. This process may provide a source of metal for the small U deposits around Mount Isa and may also suggest a relationship between U mineralization and regional Cu mobilization during the Isan orogeny. Our work suggests that non-conventional geochronometers should be used only if additional geological information and geochemical data (e.g., mineral chemistry, trace elements) are available to evaluate any resulting age calculations.

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References

  • Bain JHC, Heinrich CA, Henderson GAM (1992) Stratigraphy, structure, and metasomatism of the Haslingden Group, east Moondarra area: a deformed and mineralised Proterozoic multi-stage rift-sag sequence. In: Stewart AJ, Blake DH (eds) Detailed studies of the Mount Isa Inlier. Australian Geological Survey Organisation Bulletin 243: 125–136

  • Bau M (1991) Rare-earth element mobility during hydrothermal and metamorphic fluid-rock interaction and the significance of the oxidation state of europium. Chem Geol 93:219–230

    Article  Google Scholar 

  • Bell TH (1983) Thrusting and duplex formation at Mount Isa, Queensland, Australia. Nature 304:493–497

    Article  Google Scholar 

  • Betts P, Giles D, Mark G, Lister GS, Goleby BR, Allières L (2006) Synthesis of the Proterozoic evolution of the Mt Isa Inlier. Aust J Earth Sci 53:187–211

    Article  Google Scholar 

  • Bonazzi P, Menchetti S (2004) Manganese in monoclinic members of the epidote group: piemontite and related minerals. Rev Mineral Chem 56:495–552

    Article  Google Scholar 

  • Buick IS, Frei R, Cartwright I (1999) The timing of high-temperature retrogression in the Reynolds range, central Australia: constraints for garnet and epidote Pb–Pb dating. Contrib Miner Petrol 135:244–254

    Article  Google Scholar 

  • Cartwright I, Buick IS, Vry JK (1996) Polyphase metamorphic fluid flow in the lower calcsilicate unit, Reynolds range, central Australia. Precambrian Res 77:211–229

    Article  Google Scholar 

  • Connors KA (1992) Tectonothermal evolution of the Mount Novit Ranges, Mount Isa Inlier, Australia. PhD thesis Monash University

  • Connors KA, Lister GS (1995) Polyphase deformation in the western Mount Isa Inlier, Australia: episodic or continuous deformation? J Struct Geol 17:305–328

    Article  Google Scholar 

  • Connors KA, Page RW (1995) Relationships between magmatism, metamorphism and deformation in the western Mount Isa Inlier, Australia. Precambrian Res 71:131–153

    Article  Google Scholar 

  • Cumming GL, Richards JR (1975) Ore lead isotope ratios in a continuously changing Earth. Earth Planet Sci Lett 28:155–171

    Article  Google Scholar 

  • Dahl PS (1997) A crystal-chemical basis for Pb retention and fission-track annealing systematics in U-bearing minerals, with implications for geochronology. Earth Planet Sci Lett 150:277–290

    Article  Google Scholar 

  • DeWolf CP, Zeissler CJ, Halliday AN, Megzer K, Essene EJ (1996) The role of inclusions in U–Pb and Sm–Nd garnet geochronology: step-wise dissolution experiments and trace uranium mapping by fission track analysis. Geochim Cosmochim Acta 60:121–134

    Article  Google Scholar 

  • Dowty E (1980) Crystal-chemical factors affecting the mobility of ions in minerals. Am Miner 65:174–182

    Google Scholar 

  • Duncan RJ, Wilde AR, Bassano K, Maas R (2006) Geochronological constraints on tourmaline formation in the Western Fold Belt of the Mount Isa Inlier, Australia: evidence for large-scale metamorphism at 1.57 Ga? Precambrian Res 146:120–137

    Article  Google Scholar 

  • Duncan RJ, Wilde AR, Kobayashi K, Buick IS (2014) Chemical and stable isotopic characteristics of syn-tectonic tourmaline from the Western Fold Belt, Mount Isa Inlier, Queensland. Chem Geol. doi:10.1016/j.chemgeo.2014.05.002

    Google Scholar 

  • Farquharson RB, Richards JR (1974) U–Th–Pb isotope systematics related to igneous rocks and ore Pb, Mount Isa, Queensland. Miner Depos 9:339–356

    Article  Google Scholar 

  • Foster DRW (2003) Proterozoic low-pressure metamorphism in the Mount Isa Inlier, northwest Queensland, Australia, with particular emphasis on the use of calcic-amphibole chemistry as temperature-pressure indicators. PhD thesis James Cook University

  • Foster DRW, Rubenach MJ (2006) Isograd pattern and regional low-pressure, high-temperature metamorphism of pelitic, mafic and calc-silicate rocks along an east–west section through the Mt Isa Inlier. Aust J Earth Sci 53:167–187

    Article  Google Scholar 

  • Franz G, Liebscher A (2004) Physical and chemical properties of the epidote minerals—an introduction. Rev Mineral Chem 56:1–82

    Article  Google Scholar 

  • Frei R (1996) The extent of inter-mineral isotope equilibrium: a systematic bulk U–Pb and Pb step leaching (PbSL) isotope study of individual minerals from the Tertiary granite of Jerissis (northern Greece). Eur J Miner 8:1175–1189

    Article  Google Scholar 

  • Frei R, Kamber BS (1995) Single mineral Pb–Pb dating. Earth Planet Sci Lett 129:261–268

    Article  Google Scholar 

  • Frei R, Kramers JD, Przybylowicz WJ, Prozesky VM, Hofman BA, Kamber BS, Villa IM, Nagler TF (1997) Single mineral dating by the Pb–Pb step-leaching method: assessing the mechanisms. Geochim Cosmochim Acta 61:393–414

    Article  Google Scholar 

  • Frei D, Liebscher A, Wittenberg A, Shaw CSJ (2003) Crystal chemical controls on rare earth element partitioning between epidote-group minerals and melts: an experimental and theoretical study. Contrib Miner Petrol 146:192–204

    Article  Google Scholar 

  • Frei D, Liebscher A, Franz G, Dulski P (2004) Trace element geochemistry of epidote minerals. Rev Mineral Chem 56:553–605

    Article  Google Scholar 

  • Gale NH (1996) A new method for extracting and purifying lead from difficult matrices for isotopic analysis. Anal Chim Acta 332:15–21

    Article  Google Scholar 

  • Gieré R, Sorensen SS (2004) Allanite and other REE-rich epidote-group minerals. Rev Mineral Chem 56:431–494

    Article  Google Scholar 

  • Giles D, Betts PG, Ailleres L, Hulscher B, Hough M, Lister GS (2006) Evolution of the Isan orogeny at the southeastern margin of the Mt Isa Inlier. Aust J Earth Sci 53:91–108

    Article  Google Scholar 

  • Gregory MJ (2005) The geological evolution of the Eastern Creek Volcanics, Mount Isa, Australia and implications for the Mount Isa copper deposit. PhD Thesis Monash University

  • Gregory MJ (2006) Copper mobility in the Eastern Creek Volcanics, Mount Isa, Australia: evidence from laser ablation ICP-MS of iron-titanium oxides. Miner Depos 41:691–711

    Article  Google Scholar 

  • Gregory MJ, Wilde AR, Jones PA (2005) Uranium deposits of the Mount Isa Region and their relationship to deformation, metamorphism and copper deposition. Econ Geol 100:537–546

    Article  Google Scholar 

  • Gregory MJ, Schaefer BF, Keays RR, Wilde AR (2008) Rhenium–osmium systematics of the Mount Isa copper orebody and the Eastern Creek Volcanics, Queensland, Australia: implications for ore genesis. Miner Depos 43:553–573

    Article  Google Scholar 

  • Gulson BL, Perkins WG, Mizon KJ (1983) Lead isotope studies bearing on the genesis of copper orebodies at Mount Isa, Queensland. Econ Geol 78:1466–1504

    Article  Google Scholar 

  • Hand M, Rubatto D (2002) The scale of the thermal problem in the Mount Isa Inlier. Geol Soc Aust Abstr 67:173

    Google Scholar 

  • Hannan KW, Golding SD, Herbert HK, Krouse HR (1993) Contrasting alteration assemblages in metabasites from Mount Isa, Queensland: implications for copper ore genesis. Econ Geol 88:1135–1175

    Article  Google Scholar 

  • Heinrich CA, Bain JHC, Fardy JJ, Waring CL (1993) Br/Cl geochemistry of hydrothermal brines associated with Proterozoic metasediment-hosted copper mineralization at Mount Isa, northern Australia. Geochim Cosmochim Acta 57:2991–3000

    Article  Google Scholar 

  • Heinrich CA, Bain JHC, Mernagh TP, Wyborn LAI, Andrew AS, Waring CL (1995) Fluid and mass transfer during basalt alteration and copper mineralization at Mount Isa, Australia. Econ Geol 90:705–730

    Article  Google Scholar 

  • Ito T, Morimoto N, Sadanga R (1954) On the structure of epidote. Acta Crystallogr 7:53–59

    Article  Google Scholar 

  • Liou JG, Kim HS, Maruyama S (1983) Prehnite–Epidote equilibria and their petrological applications. J Petrol 24:321–342

    Article  Google Scholar 

  • Lottermoser BG (1989) Rare earth elements and hydrothermal ore processes. Ore Geol Rev 7:25–41

    Article  Google Scholar 

  • Ludwig KR (2003) Users manual for Isoplot 3.00: a geochronological toolkit for Microsoft Excel. Berkeley Chronological Centre Special Publication 4, Berkley, p 70

    Google Scholar 

  • Maas R, McCulloch MT, Campbell IH (1987) Sm–Nd isotope systematics in uranium-rare earth element mineralization at the Mary Kathleen uranium mine, Queensland. Econ Geol 82:1805–1826

    Article  Google Scholar 

  • McLennan SM (1989) Rare earth elements in sedimentary rocks: influence of provenance and sedimentary processes. Rev Mineral Chem 21:169–214

    Google Scholar 

  • Michard A (1989) Rare earth element systematics in hydrothermal fluids. Geochim Cosmochim Acta 53:745–750

    Article  Google Scholar 

  • Neumann NL, Southgate PN, Gibson GM, McIntyre A (2006) New SHRIMP geochronology for the Western Fold Belt of the Mt Isa Inlier: developing a 1800–1650 Ma event framework. Aust J Earth Sci 53:1023–1039

    Article  Google Scholar 

  • Norman MD, Griffin WL, Pearson NJ, Garcia MO, O’Reilly SY (1998) Quantitative analysis of trace element abundances in glasses and minerals: a comparison of laser ablation inductively coupled plasma mass spectrometry, solution inductively coupled plasma mass spectrometry, proton microprobe and electron microprobe data. J Anal At Spectrom 13:477–482

    Article  Google Scholar 

  • Nyström JO (1984) Rare earth element mobility in vesicular lava during low grade metamorphism. Contrib Miner Petrol 88:328–331

    Article  Google Scholar 

  • O’Dea MG, Lister GS, MacCready T, Betts PG, Oliver NHS, Pound KS, Huang W, Valenta RK (1997) Geodynamic evolution of the Proterozoic Mount Isa terrain. Orogeny through time. Geol Soc Lond Spec Publ 121:99–122

    Article  Google Scholar 

  • Oliver NHS, Pearson PJ, Holcombe RJ, Ord A (1999) Mary Kathleen metamorphic-hydrothermal uranium-rare-earth element deposit: ore genesis and numerical model of couple deformation and fluid flow. Aust J Earth Sci 46:467–484

    Article  Google Scholar 

  • Page RW (1983) Chronology of magmatism, skarn formation, and uranium mineralization, Mary Kathleen, Queensland, Australia. Econ Geol 78:838–853

    Article  Google Scholar 

  • Page RW, Sweet IP (1998) Geochronology of basin phases in the western Mt Isa Inlier, and correlation with the McArthur basin. Aust J Earth Sci 45:219–232

    Article  Google Scholar 

  • Page RW, Jackson MJ, Krassay AA (2000) Constraining sequence stratigraphy in north Australian basins: SHRIMP U–Pb zircon geochronology between Mt Isa and McArthur River. Aust J Earth Sci 47:431–460

    Article  Google Scholar 

  • Pan Y, Fleet ME (1996) Intrinsic and external controls on the incorporation of rare-earth elements in calc-silicate minerals. Can Mineral 34:147–159

    Google Scholar 

  • Pearce NJG, Perkins WT, Westgate JA, Gorton MP, Jackson SE, Neal SR, Chenery SP (1997) A compilation of new and published major and trace element data for NIST SRM 610 and NIST SRM 612 glass reference materials. Geostand Newslett 21:115–144

    Article  Google Scholar 

  • Romer RL (2001) Lead incorporation during crystal growth and the misinterpretation of geochronological data from low-238U/204Pb metamorphic minerals. Terra Nova 13:258–263

    Article  Google Scholar 

  • Romer RL, Siegesmund S (2003) Why allanite may swindle its true age. Contrib Mineral Petrol 146:297–307

    Article  Google Scholar 

  • Romer RL, Xiao Y (2005) Initial Pb–Sr(–Nd) isotopic heterogeneity in a single allanite–epidote crystal: implications of reaction history for the dating of minerals with low parent-to-daughter ratios. Contrib Mineral Petrol 148:662–674

    Article  Google Scholar 

  • Rubenach MJ (1992) Proterozoic low-pressure/high-temperature metamorphism and anti-clockwise P–T-t path for the Hazeldene area, Mount Isa Inlier, Queensland, Australia. J Metamorph Geol 10:333–346

    Article  Google Scholar 

  • Schaller M, Kramers JD, Steiner O, Studer I, Frei R (1997) Pb stepwise leaching (PbSL) dating of garnet—addressing the inclusion problem. Schweiz Mineral Petrogr Mitt 77:113–121

    Google Scholar 

  • Spikings RA, Kohn BP, Foster DA (2006) A regional scale low temperature (<110 °C) thermal history study of the Mt Isa and Murphy Inliers, NE Australia. Aust J Earth Sci 53:151–166

    Article  Google Scholar 

  • Stacey JS, Kramers JD (1975) Approximation of terrestrial Pb isotope evolution by a two-stage model. Earth Planet Sci Lett 26:207–221

    Article  Google Scholar 

  • Thériault RJ, Davies WJ (1999) Rapid extraction of Sr and Pb from ion-specific chromatography for thermal ionisation mass spectrometry analysis. Radiog Age Isot Stud Rep 12:9–12

    Google Scholar 

  • Tilton GR (1983) Evolution of depleted mantle: the lead perspective. Geochim Cosmochim Acta 47:1191–1197

    Article  Google Scholar 

  • Villa IM (1998) Isotopic closure. Terra Nova 10:42–47

    Article  Google Scholar 

  • Waring CL, Heinrich CA, Wall VJ (1998) Proterozoic metamorphic copper deposits. J Aust Geol Geophys 17:239–246

    Google Scholar 

  • Woodhead JD (2002) A simple method for obtaining highly accurate Pb isotope data by MC–ICP–MS. J Anal At Spectrom 17:1–6

    Article  Google Scholar 

  • Wyborn LAI (1987) The petrology and geochemistry of alteration assemblages in the Eastern Creek Volcanics, as a guide copper and uranium mobility associated with regional metamorphism and deformation, Mount Isa, Queensland. In: Pharaoh TC, Beckinsale RD, Rickard D (eds) Geochemistry and mineralization of proterozoic volcanics suites, Geological Society Special Publication no. 33, pp 425–434

  • Yang K, Scott K, Quigley M, Huntingdon J, Mason P, Hewson R (2000) Field and airborne mineral mapping in the Mt Isa Valley, Queensland: CSIRO Restricted Report 752R

  • Zartman RE, Doe BR (1981) Plumbotectonics—the model. Tectonophysics 75:135–162

    Article  Google Scholar 

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Acknowledgments

The Pb step-leaching routine presented here is derived from the unpublished intellectual property of J. Hergt, J. Woodhead, and M. Tonelli (The University of Melbourne). Without their effort, this work would not have been possible. Work here forms part of RJD’s PhD within the pmd*CRC (Predictive Minerals Discovery Cooperative Research Centre) with support from Xstrata Copper, and this paper is published with permission. We acknowledge the help of S. McKnight for his help with the epidote imaging. G. Mark, I. Buick, R. Frei, and C. Ballhaus are thanked for providing helpful comments on this manuscript.

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  1. School of Geosciences, Monash University, Melbourne, VIC, 3800, Australia

    Robert J. Duncan

  2. Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada

    Robert J. Duncan

  3. School of Earth Sciences, University of Melbourne, Melbourne, VIC, 3010, Australia

    Roland Maas

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  1. Robert J. Duncan
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Communicated by C. Ballhaus.

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Duncan, R.J., Maas, R. Assessing the origin of old apparent ages derived by Pb stepwise leaching of vein-hosted epidote from Mount Isa, northwest Queensland, Australia. Contrib Mineral Petrol 168, 1085 (2014). https://doi.org/10.1007/s00410-014-1085-4

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