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LA-ICPMS U-Pb dating reveals cassiterite inheritance in the Yazov granite, Eastern Siberia: Implications for tin mineralization

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Abstract

U-Pb dating of cassiterite and zircon from the Yazov granite (Transbaikalia region, Eastern Siberia, Russia) and cassiterite from spatially associated tin mineralization in the Tuyukan ore district in the Tonod uplift was conducted using in situ laser ablation inductively coupled plasma mass spectrometry. These analyses allow comparison of isotopic systematics for both minerals, especially related to transport in granitic magma. These data are also useful for understanding possible genetic links between the granite and the tin mineralization. Most of the U-Pb zircon analyses define a 206Pb/238U age of 719 ± 15 Ma for the granite; in addition, several zircon cores define an inheritance age of 1839 ± 21 Ma. U-Pb data for 10 nearly concordant analyses of disseminated cassiterite from the same samples yield a 206Pb/238U age of 1838 ± 34 Ma. This is the first documented evidence of cassiterite inheritance in granitic magma. These data indicate the robust character of U-Pb isotope systematics in cassiterite, comparable to that in zircon. The presence of numerous inclusions of cassiterite in zircon from the Yazov granite (revealed by nanotomography) supports the interpretation of inherited cassiterite included during Neoproterozoic zircon crystallization. The data indicate that high tin concentrations in the Yazov granite are due to the incorporation of older cassiterite crystals from country rock, not coeval cassiterite crystallization. Cassiterite samples from two ore occurrences spatially associated with the Yazov granite yield Pb-Pb isochron ages of 1.86–1.82 Ga, indicating that tin mineralization occurred in the Paleoproterozoic, nearly 1 Ga before emplacement of the Yazov granite. Tin mineralization of the ore region is probably related to ~ 1.85 Ga Chuya-Kodar tin-bearing granitic rocks that host tin deposits. These results have broad implications for understanding how critical elements, such as tin, may become enriched in rare-metal granites and how they are related to regional to global geodynamic processes.

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References

  • Aleinikoff JN, Dusel-Bacon C, Foster HL, Futa K (1981) Evidence for Proterozoic material in the Yukon-Tanana upland, east-central Alaska. Geology 9:469–473

    Article  Google Scholar 

  • Amelin YV, Neymark LA, Ritsk EY, Nemchin AA (1996) Enriched Nd–Sr–Pb isotopic signatures in the Dovyren layered intrusion (Eastern Siberia, Russia): evidence for contamination by ancient upper crustal material. Chem Geol 129:39–69

    Article  Google Scholar 

  • Ariskin AA, Kostitsyn YA, Konnikov EG, Danyushevsky LV, Meffre S, Nikolaev GS, McNeil A, Kislov EV, Orsoev DA (2013) Geochronology of the Dovyren intrusive complex, northwestern Baikal area, Russia, in the Neoproterozoic. Geochem Int 51:859–875

    Article  Google Scholar 

  • Barsukov VL (1957) On the geochemistry of tin. Geokhimiya 1:35–45 (in Russian)

    Google Scholar 

  • Black LP, Kamo SL, Allen CM, Aleinikoff JN, Davis DW, Korsch RG, Foudoulis C (2004) Improved 206Pb/238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID-TIMS, ELA-ICP-MS and oxygen isotope documentation for a series of zircon standards. Chem Geol 205:115–140

    Article  Google Scholar 

  • Cao HW, Zhang YH, Pei QM, Zhang RQ, Tang L, Lin B, Cai GJ (2017) U–Pb dating of zircon and cassiterite from the early Cretaceous Jiaojiguan iron-tin polymetallic deposit, implications for magmatism and metallogeny of the Tengchong area, western Yunnan, China. Intern Geol Rev 59:234–238

    Article  Google Scholar 

  • Carr PA, Zink S, Bennett VC, Norman MD, Amelin Y, Blevin PL (2020) A new method for U-Pb geochronology of cassiterite by ID-TIMS applied to the Mole Granite polymetallic system, eastern Australia. Chem Geol 539. https://doi.org/10.1016/j.chemgeo.2020.119539

  • Crowley JL, Brown RL, Gervais F, Gibson HD (2008) Assessing inheritance of zircon and monazite in granitic rocks from the Monashee complex, Canadian cordillera. J Petrol 49:1915–1929

    Article  Google Scholar 

  • Donskaya TV (2020) Assembly of the Siberian craton: constraints from Paleoproterozoic granitoids. Precambrian Res 348: (in press):105869. https://doi.org/10.1016/j.precamres.2020.105869

    Article  Google Scholar 

  • Dulski P, Moller P, Villalpando A, Schneider (1982) Correlation of trace element fractionation in cassiterites with the genesis of the Bolivian metallotectonic province. In: Evans AM (ed) Metallization associated with acid Magmatism. John Wiley and Sons, Chichester and New York, pp. 71–83

  • Evans DAD, Mitchell RN (2011) Assembly and breakup of the core of Paleoproterozoic-Mesoproterozoic supercontinent Nuna. Geology 39:443–446

    Article  Google Scholar 

  • Farmer CC, Searl A, Halls C (1991) Cathodoluminescence and growth of cassiterite in the composite lodes at South Crofty mine, Cornwall, England. Min Mag 55:447–458

    Article  Google Scholar 

  • Gladkochub D, Pisarevsky S, Donskaya T, Natapov L, Mazukabzov A, Stanevich A, Sklyarov E (2006) The Siberian craton and its evolution in terms of the Rodinia hypothesis. Episodes 29:169–174

    Article  Google Scholar 

  • Haapala I (1997) Magmatic and postmagmatic processes in tin-mineralized granites: topaz-bearing leucogranite in the Eurajoki rapakivi granite stock, Finland. J Petrol 38:1645–1659

    Article  Google Scholar 

  • Hall MR, Ribbe PH (1971) An electron microprobe study of luminescence centers in cassiterite. Am Mineral 56:31–45

    Google Scholar 

  • Heaman LM, LeCheminant AN, Rainbird RH (1992) Nature and timing of Franklin igneous events, Canada: implications for a late Proterozoic mantle plume and the break-up of Laurentia. Earth Planet Sci Lett 109:117–131

    Article  Google Scholar 

  • Hoskin PWO, Black LP (2000) Metamorphic zircon formation by solid-state recrystallization of protolith igneous zircon. J Metamorphic Geol 18:423–439

    Article  Google Scholar 

  • Hu Z, Gao S, Liu Y, Hu,S, Chen H, Yuan H (2008) Signal enhancement in laser ablation ICP-MS by addition of nitrogen in the central channel gas: J Analyt Atom Spectrom 23:1093–1101

  • Ishihara S (1977) The magnetite-series and ilmenite-series granitic rocks. Mining Geology 27:293–305

    Google Scholar 

  • Ivanov AI, Livshits VI, Perevalov OV, Strakhova TM, Yablonovsky BV, Il’yinskaya MI, Graizer HG, Golovenok VK (1995) Precambrian of the Patom highlands. Nedra, Moscow (in Russian), 351 p. ISBN 5-247-03174-1

    Google Scholar 

  • Khain E, Kröner A, Gibsher A, Fedotova A (2001) The fate of Rodinia in the light of the discovery of ca. 1000 Ma old ophiolites in the central Asian Orogenic Belt of Siberia. Gondwana Res 4:656–657

    Article  Google Scholar 

  • Kovalenko VI (1978) The genesis of rare metal granitoids and related ore deposits: in. Metallization Associated with Acid Magmatism Symp 3:235–248

    Google Scholar 

  • Krogh TE (1973) A low-contamination method for hydrothermal decomposition of zircon and extraction U and Pb for isotopic age determinations. Geochim Cosmochim Acta 37:485–494

    Article  Google Scholar 

  • Kuzmin MI, Yarmolyuk VV (2014) Mantle plumes of Central Asia (Northeast Asia) and their role in forming endogenous deposits. Russial Geol Geophys 55:120–143

    Article  Google Scholar 

  • Larin AM, Ritsk Ye Yu, Sokolov Yu M (1997) Baikal-Patom fold belt. Chapter 17. In: Precambrian ore deposits of the east european and siberian cratons, DV Rundkvist and C Gillen Eds, pp. 317–362. https://www.sciencedirect.com/bookseries/developments-in-economic-geology/vol/30

  • Larin AM, Sal’nikova EB, Kotov AB, Makar’ev LB, Yakovleva SZ, Kovach VP (2006) Early Proterozoic syn-and postcollision granites in the northern part of the Baikal fold area. Stratigraphy Geol Correl 14:463–474

    Article  Google Scholar 

  • Larin AM, Kotov AB, Sal’nikova EB, Sklyarov EV, Kovach VP, Plotkina Yu. V, Anisimova IV, Podolskaya MM (2020) Age, sources and tectonic setting of the tin-bearing granites of the Yazovka complex of the Baikal-Patom fold-thrust belt. Doklady Earth Sci 490:10–14. https://doi.org/10.1134/S1028334X20020075

    Article  Google Scholar 

  • Lehmann B (1982) Metallogeny of tin; magmatic differentiation versus geochemical heritage. Econ Geol 77:50–59

    Article  Google Scholar 

  • Lehmann B (1987) Tin granites, geochemical heritage, magmatic differentiation. Geol Rundsch 76(1):177–185

    Article  Google Scholar 

  • Lehmann B (2020) Formation of tin ore deposits: a reassessment. Lithos: in press:105756. https://doi.org/10.1016/j.lithos.2020.105756

  • Lehmann B, Zoheir B, Neymark L, Zeh A, Emam A, Radwan A, Zhang R, Moscati R (2020) Monazite and cassiterite U\\Pb dating of the Abu Dabbab rare-metal granite, Egypt: Late Cryogenian metalliferous granite magmatism in the Arabian-Nubian shield. Gondwana Res 84:71–80

    Article  Google Scholar 

  • Lerouge C, Gloaguen E, Wille G, Bailly L (2017) Distribution of In and other rare metals in cassiterite and associate minerals in Sn ± W ore deposits of the western Variscan belt. Euro Jour Min 29:739–753

    Article  Google Scholar 

  • Li CY, Zhang RQ, Ding X, Ling MX, Fan WM, Sun WD (2016) Dating cassiterite using laser ablation ICP-MS. Ore Geol Rev 72:313–322

    Article  Google Scholar 

  • Linnen RL, Pichavant M, Holtz F (1996) The combined effects of fO2 and melt composition on SnO2 solubility and tin diffusivity in haplogranitic melts. Geochim Cosmochim Acta 60:4965–4976

    Article  Google Scholar 

  • Ludwig KR (1987) PBDAT for MS-DOS. A computer program for IBM-PC compatibles for processing raw Pb-U-Th isotope data. U.S. Geological Survey Open-File Rep 88–542, 40 pp.

  • Ludwig KR (2012) Isoplot/Ex rev. 4.15- A geochronological toolkit for Microsoft Excel: Berkeley Geochronology Center. Special publication No. 5, 75 p. http://www.bgc.org/isoplot_etc/isoplot.html

  • McDonough WF, Sun S (1995) The composition of the earth. Chem Geol 120:223–253

  • Miller CF, McDowell SM, Mapes RW (2003) Hot and cold granites? Implications of zircon saturation temperatures and preservation of inheritance. Geology 31:529–532

  • Mitrofanova NN, Boldyrev VI, Korobeinikov NK, Mitrofanov GL, Knutova SV, Semeikina LK, Pai VM, Vladimirov AE, Goryainiva LN, Makariev LB (2012) State geological map of the Russian Federation. Scale 1: 1,000,000 (third generation). Series Aldano-Zabaykalskaya. Sheet O-49 -Kirensk. Explanatory note. SPb: VSEGEI Map factory (in Russian). http://www.geokniga.org/sites/geokniga/files/mapcomments/o-49-kirensk-gosudarstvennaya-geologicheskaya-karta-rossiyskoy-federacii-tret.pdf

  • Möller P, Dulski P, Szacki W, Malow G, Riedel E (1988) Substitution of tin in cassiterite by tantalum, niobium, tungsten, iron and manganese. Geochim Cosmochim Acta 52:1497–1503

    Article  Google Scholar 

  • Moscati RJ, Neymark LA (2020) U–Pb geochronology of tin deposits associated with the Cornubian batholith of Southwest England: direct dating of cassiterite by in situ LA-ICPMS. Mineral Deposita 55:1–20

    Article  Google Scholar 

  • Neimark LA, Rytsk EY, Levchenkov OA, Komarov AN, Yakovleva SZ, Nemchin AA, Shuleshko IK, Korikovskii SP (1990) Paleoproterozoic–Early Riphean rocks in the Olokit Complex: U–Pb zircon dates. In: Precambrian Geology and Geochronology of the Siberian Platform and its Surroundings (Nauka, Leningrad), pp 206–222 [in Russian]

    Google Scholar 

  • Neymark LA, Holm-Denoma CS, Moscati RJ (2018) In situ LA-ICPMS U–Pb dating of cassiterite without a known-age matrix-matched reference material: examples from worldwide tin deposits spanning the Proterozoic to the Tertiary. Chem Geol 483:410–425

    Article  Google Scholar 

  • Paces JB, Miller JD Jr (1993) Precise U-Pb ages of Duluth Complex and related mafic intrusions, northeastern Minnesota: Geochonological insights to physical, petrogenetic, paleomagnetic and tectono-magmatic processes associated with the 1.1 Ga Midcontinent rift system. J Geophys Res 98(B8):13997–14013

    Article  Google Scholar 

  • Palenova EE, Yudovskaya MA, Frei D, Rodionov NV (2019) Detrital zircon U–Pb ages of Paleo- to Neoproterozoic black shales of the Baikal-Patom highlands in Siberia with implications to timing of metamorphism and gold mineralization. J Asian Earth Sci 174:37–58

    Article  Google Scholar 

  • Paton C, Hellstrom J, Paul B, Woodhead J, Hergt J (2011) Iolite: freeware for the visualisation and processing of mass spectrometric data. J Analyt At Spectrom 26:2508–2518

    Article  Google Scholar 

  • Patterson BA, Stephens WE, Rogers G, Williams IS, Hinton RW, Herd DA (1992) The nature of zircon inheritance in two granite plutons. Trans Royal Soc Edinburgh 83:459–471

    Article  Google Scholar 

  • Pearce JA, Harris NBW, Tindle AG (1984) Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. J Petrol 25, Part 4:956–983

    Article  Google Scholar 

  • Pietruszka A, Neymark L (2017) Evaluation of laser ablation double-focusing SC-ICP-MS for “common” lead isotopic measurements in silicate glasses and minerals. J Analyt At Spectrom 32:1135–1154

    Article  Google Scholar 

  • Powerman V, Shatsillo A, Chumakov N, Kapitonovc I, Hourigane J (2015) Interaction between the central Asian orogenic belt (CAOB) and the Siberian craton as recorded by detrital zircon suites from Transbaikalia. Precambrian Res 207:39–71

    Article  Google Scholar 

  • Roddick JC, Bevier ML (1995) U-Pb dating of granites with inherited zircon: conventional and ion microprobe results from two Paleozoic plutons, Canadian Appalachians. Chem Geol 119:307–329

    Article  Google Scholar 

  • Rudnick RL, Gao S (2003) Composition of the continental crust. In: Holland HD, Turekian KK (eds) Treatise on geochemistry, vol 3. Elsevier, Amsterdam, pp 1–64

    Google Scholar 

  • Rytsk EY, Shalaev VS, Rizvanova NG, Krymsky RS, Makeev AF, Rile GV (2002) The Olokit zone of the Baikal folded area: new data on isotopic and major- and trace-element compositions. Geotektonika 1:29–41 (in Russian)

    Google Scholar 

  • Sal’nikova EB, Larin AM, Yakovleva SZ, Kotov AB, Glebovitskii VA, Tkachev AV, Anisimova IV, Plotkina YV, Gorokhovskii BM (2011) Age of the Vishnyakovskoe deposit of rare-metal Pegmatites (East Sayan): U–Pb geochronological study of manganotantalite. Doklady Earth Sci 441:1479–1483. https://doi.org/10.1134/S1028334X11110080

    Article  Google Scholar 

  • Schultz KJ, DeYoung JH, Bradley DC, Seal RS II (2017) Critical mineral resources of the United States. U.S. Geological Survey Professional Paper 1802, 797 p. https://doi.org/10.3133/pp1802

  • Sláma J, Košler J, Condon DJ, Crowley JL, Gerdes A, Hanchar JM, Horstwood MSA, Morris GA, Nasdala L, Norberg N, Schaltegger U, Schoene B, Tubrett MN, Whitehouse MJ (2008) Plešovice zircon—a new natural reference material for U-Pb and Hf isotopic microanalysis. Chem Geol 249:1–35. https://doi.org/10.1016/j.chemgeo.2007.11.005

    Article  Google Scholar 

  • Smith WD, Darling JR, Bullen DS, Lasalle S, Pereira I, Moreira H, Allen CJ, Tapster S (2019) Zircon perspectives on the age and origin of evolved S-type granites from the Cornubian batholith, Southwest England. Lithos 336-337:14–24

    Article  Google Scholar 

  • Souders AK, Sylvester PJ (2010) Accuracy and precision of non-matrix-matched calibration for lead isotope ratio measurements of lead-poor minerals by LA-MC-ICPMS. J Analyt At Spectrom 25:975–988

    Article  Google Scholar 

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

    Article  Google Scholar 

  • Tapster S, Bright JWG (2020) High-precision ID-TIMS cassiterite U-Pb systematics using a low-contamination hydrothermal decomposition: implications for LA-ICP-MS and ore deposit geochronology. Geochronology, Discussions 2:425–441. https://doi.org/10.5194/gchron-2019-22

    Article  Google Scholar 

  • Tera F, Wasserburg GJ (1972) U-Th-Pb systematics in three Apollo 14 basalts and the problem of initial Pb in lunar rocks. Earth Planet Sci Lett 14:281–304

    Article  Google Scholar 

  • Tkachev AV (2011) Evolution and metallogeny of granitic pegmatites associated with orogens throughout geo-logical time. Geo. Soc London Spec Pub 350:7–23

    Article  Google Scholar 

  • von Humboldt A (1823) Essai géognostique sur le gisement des roches dans les deux hémisphères. Levrault, Strasbourg, 364 pp

    Google Scholar 

  • Watson EB, Harrison MT (1983) Zircon saturation revisited: temperature and composition effects in a variety of crustal magma types. Earth Planet Sci Lett 64:295–304

    Article  Google Scholar 

  • Wille G, Lerouge C, Schmidt U (2018) A multimodal microcharacterization of trace-element zonation and crystallographic orientation in natural cassiterite by combining cathodoluminescence, EBSD, EPMA and contribution of confocal Rama-in-SEM imaging. J Microsc 270:309–317

    Article  Google Scholar 

  • Yan Q-H, Qiu Z-W, Wang H, Wang M, Wei X-P, Li P, Zhang R-Q, Li C-Y, Liu J-P (2016) Age of the Dahongliutan rare metal pegmatite deposit, West Kunlun, Xinjiang (NW China): Constraints from LA–ICP–MS U–Pb dating of columbite-(Fe) and cassiterite. Ore Geol Rev 100:561–573

    Article  Google Scholar 

  • Yarmolyuk VV, Kovalenko VI, Kovach VP, Rytsk EY, Kozakov IK, Kotov AB, Sal’nikova EB (2006) Early stages of the Paleoasian ocean formation: results of geochronological, isotopic, and geochemical investigations of late Riphean and Vendian–Cambrian complexes in the central Asian Foldbelt. Doklady Earth Sci 411:1184–1189. https://doi.org/10.1134/2FS1028334X06080046

    Article  Google Scholar 

  • Yuan S, Peng J, Hao S, Li H, Geng J, Zhang D (2011) In situ LA-MC-ICP-MS and ID-TIMS U–Pb geochronology of cassiterite in the giant Furong tin deposit, Hunan Province, South China: new constraints on the timing of tin–polymetallic mineralization. Ore Geol Rev 43:235–242

    Article  Google Scholar 

  • Zagorsky VYE, Vladimirov AG, Makagon VM, Kuznetsova LG, Smirnov SZ, D’yachkov BA, IYu A, Shokalsky SP, Uvarov AN (2014) Large fields of spodumene pegmatites in the settings of rifting and postcollisional shear–pull-apart dislocations of continental lithosphere. Russ Geol Geophys 55:237–251

    Article  Google Scholar 

  • Zartman RE, Hermes OD (1987) Archean inheritance in zircon from late Paleozoic granites from the Avalon zone of southeastern New England: an African connection. Earth Planet Sci Lett 82:305–315

    Article  Google Scholar 

  • Zhang DL, Peng JT, Hu RZ, Yuan SD, Zheng DS (2011) The closure of U-Pb isotope system in cassiterite and its reliability for dating. Geol Rev 57:549–554 (in Chinese with English abstract)

    Google Scholar 

  • Zhang D, Peng J, Coulson IM, Hou L, Li H (2014) Cassiterite U–Pb and muscovite 40Ar–39Ar age constraints on the timing of mineralization in the Xuebaoding Sn–W–be deposit, western China. Ore Geol Rev 62:315–322

    Article  Google Scholar 

  • Zhang R, Lu J, Lehmann B, Hou L, Li C, Li G, Zhang L, Guo J, Sun W (2017) Combined zircon and cassiterite U–Pb dating of the Piaotang granite related tungsten–tin deposit, southern Jiangxi tungsten district, China. Ore Geol Rev 82:268–284

    Article  Google Scholar 

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Acknowledgments

We are indebted to our colleagues Dave Adams and Heather Lowers who provided generous help at the U.S. Geological Survey Microbeam Lab in Denver. Special thanks to John Aleinikoff (U.S. Geological Survey), Chris McFarlane (University of New Brunswick), and Bernd Lehmann (Technical University of Clausthal) who provided constructive and thoughtful reviews of this manuscript.

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The work at IPGG was supported by the RFFI research grant №18-05-00403.

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  1. U.S. Geological Survey, Denver Federal Center, Box 25046, MS 963, Denver, CO, 80225, USA

    L. A. Neymark, C. S. Holm-Denoma & R. J. Moscati

  2. Institute of Precambrian Geology and Geochronology of Russian Academy of Sciences, 2 Makarova emb., St. Petersburg, 199034, Russia

    A. M. Larin & Yu. V. Plotkina

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Neymark, L.A., Holm-Denoma, C.S., Larin, A.M. et al. LA-ICPMS U-Pb dating reveals cassiterite inheritance in the Yazov granite, Eastern Siberia: Implications for tin mineralization. Miner Deposita 56, 1177–1194 (2021). https://doi.org/10.1007/s00126-020-01038-9

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