Abstract
The knowledge of the age of an LCT pegmatite mineralisation is one of the key exploration criteria as most of the major LCT pegmatite systems (e.g., Tanco, Greenbushes, Bikita, Wodgina) were formed in relative narrow time intervals within the earth history. In addition, the temporal and spatial relation-ships of the pegmatites to potential source granites, their crystallisation history and geotectonic settings are still under debate. For the evaluation of the petrogenesis and emplacement history we compared Meso- and Neo-Archean LCT pegmatites of the Zimbabwe (Bikita), Pilbara (Wodgina) and Yilgarn Cratons (Londonderry, Mount Deans, Cattlin Creek). Lepidolite and white mica and lepidolite are an abundant constituent of the investigated LCT pegmatites and potentially accessible for 40Ar/39Ar dating. The U–Pb dating of Ta–Nb–Sn oxides and cassiterite LA-ICPMS turned out to be suitable for the Neo-Archean pegmatites due to the widespread occurrence of these minerals as accessories in almost all samples. Furthermore, they are formed at a virtually constant level during pegmatite crystallisation from main crystallisation to late state hydrothermal overprint. The 40Ar/39Ar ages cover a large spectrum from Neoarchean (~2630 Ma) to Paleoproterozoic (~2316 Ma), and are verified by U/Pb tantalite/ columbite ages (~2870 to 2615 Ma, LA-ICP-MS) and by Th-U-Pb electron microprobe monazite ages (~2700 Ma; ~2500 Ma). Micas from the Yilgarn Craton yield Neoarchean cooling ages indicating an immediate cooling after crystallisation. In contrast, micas from the Zimbabwe (~2625 Ma) and Pilbara Craton (~2870 Ma) exhibit Paleoproterozoic cooling ages that significantly postdate initial crystallisation. This is in good agreement with petrographic data that suggests a post pegmatite hydrothermal overprint. Overall, our new age data are in good agreement with a previously postulated global major LCT pegmatite events between 2850 to 2800 Ma and 2650 to 2600 Ma. During this event specific geodynamic conditions (i.e. a super-continent assembly) and associated anormal high heat flow from the mantle enabled the global formation of large volumes of LCT pegmatites.
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References
Cawood PA, Tyler IM (2004) Assembling and reactivating the Proterozoic Capricorn Orogen; lithotectonic elements, orogenies, and significance. Precambr Res 128:201–218
Dittrich T (2016) Meso- to Neoarchean Lithium-Cesium-Tantalum- (LCT-) pegmatites (Western Australia, Zimbabwe) and a genetic model for the formation of massive pollucite mineralisations. Dissertation Faculty of Geosciences, Geoengineering and Mining, TU Freiberg/Saxony, Germany, 341 pp. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-228968
Dittrich T, Seifert T, Schulz B, Pfänder J, Gerdes A (2017) Formation of LCT pegmatites in archean cratons: constraints from 40Ar/39Ar Mica, U–Th–Pb Monazite and U–Pb Tantalite/Columbite dating. Goldschmidt 2017 Conference, Paris, Abstracts, p 959
Harrison TM, Célérier J, Aikman AB, Hermann J, Heizler MT (2009) Diffusion of 40Ar in muscovite. Geochim Cosmochim Acta 73:1039–1051
Jeffrey PM (1956) The radioactive age of four Western Australian pegmatites by the potassium and rubidium methods. Geochim Cosmochim Acta 10:191–195
Jelsma HA, Vinyu ML, Valbrachet PJ, Davies GR, Wijbrans JR, Verdurmen EAT (1996) Constraints on Archaean crustal evolution of the Zimbabwe craton: A U–Pb zircon, Sm–Nd and Pb–Pb whole-rock isotope study. Contrib Mineral Petrol 124:55–70
Kennedy AK (1998) SHRIMP ages of apatites from Pilbara tin-bearing pegmatites. Geol Soc Austral Abstracts 49:242
Kinny PD (2000) U–Pb dating of rare metal (Sn–Ta–Li) mineralized pegmatites in Western Australia by SIMS analysis of tin and tantalum bearing ore minerals. New Frontiers in Isotope Geoscience Abstracts and Proceedings Lorne (Australia), pp 113–116
Ludwig KR (2003) User manual for isoplot/ex. rev. 2.49.2. a geochronological toolkit for microsoft Excel. Berkeley Geochronological Center Spec Publ 1a, 55 pp
Melcher F, Graupner T, Gäbler HE, Sitnikova M, Henjes-Kunst F, Oberthuer T, Gerdes A, Dewaele S (2015) Tantalum-(niobium-tin) mineralisation in African pegmatites and rare metal granites: constraints from Ta–Nb oxide mineralogy, geochemistry and U–Pb geochronology. Ore Geol Rev 64:667–719. https://doi.org/10.1016/j.oregeorev.2013.09.003
Montel JM, Foret S, Veschambre M, Nicollet C, Provost A (1996) Electron microprobe dating of monazite. Chem Geol 131:37–53
Oberthuer T, Davis DW, Blenkinson TG, Höhndorf A (2002) Precise U–Pb mineral ages, Rb–Sr and Sm–Nd systematics for the Great Dyke, Zimbabwe—constraints on late Archean events in the Zimbabwe craton. Precambr Res 113:293–305
Rasmussen B, Fletcher IR, Sheppard S (2005) Isotopic dating of the migration of a low-grade metamorphic front during orogenesis. Geology 33:773–776
Seydoux-Guillaume AM, Paquette JL, Wiedenbeck M, Montel JM, Heinrich WH (2002) Experimental resetting of the U–Th–Pb systems in monazite. Chem Geol 191:165–181
Soederlund U, Hofmann A, Klausen MB, Olsson JR, Ernst RE, Persson PO (2010) Towards a complete magmatic barcode for the Zimbabwe craton: baddeleyite U–Pb dating of regional dolerite dyke swarms and sill complexes. Precambr Res 183:388–398
van Kranendonk MJ, Hickman AH, Smithies RH, Williams IR, Bagas L, Farrell TR (2006) Revised lithostratigraphy of Archean supracrustal and intrusive rocks in the northern Pilbara Craton, Western Australia. Geol Surv West Austral Record 2006–15, 63 pp
van Kranendonk MJ, Smithies RH, Hickman AH, Champion DC (2007) Review: secular tectonic evolution of Archean continental crust: interplay between horizontal and vertical processes in the formation of the Pilbara Craton, Australia. Terra Nova 19:1–38
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Dittrich, T., Seifert, T., Schulz, B., Hagemann, S., Gerdes, A., Pfänder, J. (2019). Geochronology of Archean LCT Pegmatites. In: Archean Rare-Metal Pegmatites in Zimbabwe and Western Australia. SpringerBriefs in World Mineral Deposits. Springer, Cham. https://doi.org/10.1007/978-3-030-10943-1_5
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