Abstract
Inherited zircons from S-type granites provide exceptionally good insight into the isotopic heterogeneity of their sources. Zircons from four samples (one granite, two granodiorites, one granodioritic enclave) of Pan-African S-type granite of the Cape Granite Suite (c. 540 Ma) have been the subject of a laser LA-ICP-MS zircon U/Pb study to determine emplacement ages and inheritance. Zircons from three of these samples (2 granodiorites and 1 granodioritic enclave) were also analysed for Hf isotopes by LA-MC-ICP-MS. Ages of inherited cores range from 1,200 to 570 Ma and show Hafnium isotope values (εHf,t ) for the crystallisation age (t) of the different cores that range from −14.1 to +9.1. Magmatic zircons and magmatic overgrowth with concordant spot ages between ca. 525 and ca. 555 Ma show a similar range of εHf,t , between −8.6 and +1.5, whilst εHf values calculated at 540 Ma (εHf,540) for inherited cores range from −15.2 to +1.7. Thus, our results show that the time evolved εHf arrays of the inherited cores overlap closely with the εHf range displayed by the magmatic rims at the time of crystallisation of the pluton. These similarities imply a genetic relationship between magmatic and inherited zircons. Within the inherited cores, four main peak ages can be identified. This, coupled with their large Hf isotopic range, emphasises that the source of the granite is highly heterogeneous. The combination of the U/Pb zircon ages ranges and Hf isotope data implies that: (1) The source of S-type granite consists of crustal material recording several regional events between 1,200 and 600 Ma. This material records the recycling of a much older crust derived from depleted mantle between 1.14 and 2.02 Ga. (2) The homogenisation of Hf isotopic variation in the magma acquired through dissolution of the entrained zircon, via mechanical mixing and/or diffusion between within the granite was particularly inefficient. (3) This evidence argues for the assembly of the pluton through many relatively small magma batches that undergo rapid cooling from their intrusion temperature (ca. 850°C) to background magma chamber temperature that is low enough to ensure that much of the magmatic zircon crystallised rapidly (>80% by 700°C). (4) There is no evidence for the addition of mantle-derived material in the genesis of S-type Cape Granite Suite, where the most mafic granodiorites are strongly peraluminous, relatively low in CaO and K2O rich. Interpreted more widely, these findings imply that S-type granites inherit their isotopic characteristic from the source. Source heterogeneity transfers to the granite magma via the genesis of discrete magma batches. The information documented from the S-type CGS zircons has been recorded because the individual batches of magma crystallised the bulk of their magmatic zircon prior to mechanical or diffusional magma homogenisation. This is favoured by zirconium saturation in the magma shortly after emplacement, by partial dissolution of the entrained zircon fraction, as well as by the intrusion of volumetrically subordinate magma batches into a relatively cool pluton. Consequently, evidence recorded within inherited cores will most likely be best preserved in S-type granite plutons intruded at shallow depths. Other studies that have documented similar εHf arrays in magmatic zircons have interpreted these to reflect mixing between crustal- and mantle-derived magmas. This study indicates that such arrays may be wholly source inherited, reflecting mixing of a range of crustal materials of different ages and original isotopic signatures.
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References
Allégre CJ, Rousseau D (1984) The growth of the continent through geological time studied by Nd isotope analysis of shales. Earth Planet Sci Lett 67:19–34
Andersen T (2002) Correction of common lead in U–Pb analyses that do not report 204Pb. Chem Geol 192:1–12
Appleby SK, Gillespie MR, Graham CM, Hinton RW, Oliver GJH, Kelly NM, EIMF (2010) Do S-type granites commonly sample infracrustal sources? New results from an integrated O, U–Pb and Hf isotope study of zircon. Contrib Mineral Petrol 160:115–132
Armstrong RA, De Wit MJ, Reid DL, York D, Zattman R (1998) Table Mountain reveals rapid Pan-African uplift of its basement rocks. J Afr Earth Sci 27:10–11
Bea F, Montero P, Gonzalez-Lodeiro F, Talavera C (2007) Zircon inheritance reveals exceptionally fast crustal magma generation processes in central Iberia during the Cambro-Ordovician. J Petrol 48:2327–2339
Belcher RW, Kisters AFM (2003) Lithos stratigraphic correlations in the western branch of the Pan-African Saldania belt, South Africa: the Malmesbury group revisited. South Afr J Geol 106:327–342
Belousova EA, Griffin WL, O’Reilly SY (2006) Zircon crystal morphology, trace element signatures and Hf isotope composition as a tool for petrogenetic modelling: examples from Eastern Australian granitoids. J Petrol 47:329–353
Black LP, Kamo SL, Allen CM, Davis DW, Aleinikoff JN, Valley JW, Mundil R, Campbell IH, Korsch RJ, Williams IS, 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
Blichert-Toft J, Albarede F (1997) The Lu–Hf geochemistry of chondrites and the evolution of the mantle-crust system. Earth Planet Sci Lett 148:243–258
Bodet F, Scharer U (2000) Evolution of the SE-Asian continent from U–Pb and Hf isotopes in single grains of zircon and baddeleyite from large rivers. Geochim Cosmochim Acta 64:2067–2091
Buick IS, Hand M, Williams IS, Mawby J, Miller JA, Nicoll RS (2005) Detrital zircon provenance constraints on the evolution of the Harts range metamorphic complex (central Australia): links to the Centralian Superbasin. J Geol Soc 162:777–787
Cawood PA, Buchan C (2007) Linking accretionnary orogenesis with supercontinent assembly. Earth Sci Rev 82:217–256
Chappell BW (1996) Magma mixing and the production of compositional variation within granite suites: evidence from the granites of Southeastern Australia. J Petrol 37:449–470
Chemale F, Scheepers R, Gresse PG, Schmus WRV (2011) Geochronology and sources of late Neoproterozoic to Cambrian granites of the Saldania Belt. Int J Earth Sci 100:431–444
Chu NC, Taylor RN, Chavagnac V, Nesbitt RW, Boella RM, Milton JA, German CR, Bayon G, Burton K (2002) Hf isotope ratio analysis using multi-collector inductively coupled plasma mass spectrometry: an evaluation of isobaric interference corrections. J Anal At Spectrom 17:1567–1574
Clemens JD (2003) S-type granitic magmas—petrogenetic issues, models and evidence. Earth Sci Rev 61:1–18
Clemens JD, Stevens G, Farina F (2011) The enigmatic sources of I-type granites: the peritectic connexion. Lithos (in press)
Clifford TN, Barton ES, Stern RA, Duchesne JC (2004) U–Pb zircon calendar for Namaquan (Grenville) crustal events in the granulite-facies terrane of the O’okiep Copper District of South Africa. J Petrol 45:669–691
Collins WJ (1996) Lachlan fold belt granitoids: products of three-component mixing. Trans R Soc Edinburgh Earth Sci 87:171–179
Collins WJ (1998) Evaluation of petrogenetic models for Lachlan fold belt granitoids: implications for crustal architecture and tectonic models. Aust J Earth Sci 45:483–500
Da Silva LC, Gresse PG, Scheepers R, McNaughton NJ, Hartman LA, Fletcher I (2000) U–Pb SHRIMP and Sm-Nd age constraints on the timing and sources of the Pan-African Cape Granite Suite, South Africa. J Afr Earth Sci 30:795–815
Eglington BM, Armstrong RA (2003) Geochronological and isotopic constraints on the Mesoproterozoic Namaqua-Natal belt: evidence from deep borehole intersection in South Africa. Precambrian Res 125:179–189
Gray CM (1984) An isotopic mixing model for the origin of granitic rocks in southeastern Australia. Earth Planet Sci Lett 70:47–60
Griffin WL, Wang X, Jackson SE, Pearson NJ, O’Reilly SY, Xu X, Zhou X (2002) Zircon chemistry and magma mixing, SE China: in situ analysis of Hf isotopes, Tonglu and Pingtan igneous complexes. Lithos 61:237–269
Harris C, Faure K, Diamond RE, Scheepers R (1997) Oxygen and hydrogen isotope geochemistry of S- and I-type granitoids: the Cape Granite Suite, South Africa. Chem Geol 143:95–114
Harrison TM, Blichert-Toft J, Muller W, Albarede F, Holden P, Mojzsis SJ (2005) Heterogeneous Hadean Hafnium: evidence of continental crust at 4.4 to 4.5 Ga. Science 310:1947–1950
Hartnady CJH, Newton AR, Theron JN (1974) The stratigraphy and structure of the Malmesbury Group in the southwestern Cape. Bull Precambrian Res Unit 15:193–213
Hauser N, Matteini M, Omarini RH, Pimentel MM (2010) Combined U–Pb and Lu–Hf isotopes data on turbidites of the palaeozoic basement of NW Argentina and petrology of associated igneous rocks: implications for the tectonic evolution of western Gondwana between 560 and 460 Ma. Gondwana Res 19:100–127
Hervé F, Fanning CM, Pankhurst RJ (2003) Detrital zircon age patterns and provenance of the metamorphic complexes of southern Chile. J South Am Earth Sci 16:107–123
Jackson SE, Pearson NJ, Griffin WL, Belousova EA (2004) The application of laser ablation-inductively coupled plasma-mass spectrometry to in situ U–Pb zircon geochronology. Chem Geol 211:47–49
Keay S, Collins WJ, McCulloch MT (1997) A three-component Sr-Nd isotopic mixing model for granitoid genesis, Lachlan fold belt, eastern Australia. Geology 25:307–310
Kemp AIS, Hawkesworth CJ, Paterson BA, Kinny PD (2006) Episodic growth of the Gondwana supercontinent from hafnium and oxygen isotopes in zircon. Nature 439:580–583
Kemp AIS, Hawkesworth CJ, Foster GL, Paterson BA, Woodhead JD, Hergt JM, Gray CM, Whitehouse MJ (2007) Magmatic and Crustal differenciation history of granitic rocks from Hf-O Isotopes in Zircon. Science 315:980–984
Kemp AIS, Hawkesworth CJ, Paterson BA, Foster GL, Kinny PD, Whitehouse MJ, Maas R, MF EI (2008) Exploring the plutonic-volcanic link: a zircon U–Pb, Lu–Hf and O isotope study of paired volcanic and granitic units from southeastern Australia. Trans R Soc Edinburgh Earth Sci 97:337–355
Ludwig KR (2003) User’s manual for Isoplot v 3.00. A geochronological toolkit for Microsoft Excel. Berkeley Geochoronological Center Spec Pub no 4
Miller CF, Meschter-McDowell S, Mapes RW (2003) Hot and cold granites? Implications of zircon saturation temperatures and preservation of inheritance. Geology 31:529–532
Patchett PJ, Kouvo O, Hedge CE, Tatsumoto M (1981) Evolution of continental crust and mantle heterogeneity: evidence from Hf isotopes. Contrib Mineral Petrol 78:279–297
Paterson BA, Stephens WE, Rogers G, Williams IS, Hinton RW, Herd DA (1992) The nature of zircon inheritance in two granite plutons. Trans R Soc Edinburgh Earth Sci 83:459–471
Pearce NJG, Perkins WT, Westgate JA, Gorton MP, Jackson SE, Meal CR, 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 J Geostand Geoanal 21:115–144
Rozendaal A, Gresse PG, Scheepers R, Le Roux JP (1999) Neoproterozoic to early Cambrian crustal evolution of the Pan-African Saldania belt, South Africa. Precambrian Res 97:303–323
Sambridge MS, Compston W (1994) Mixture modeling of multi-component data sets with application to ion-probe zircon ages. Earth Planet Sci Lett 128:373–390
Scheepers R (1995) Geology, geochemistry and petrogenesis of late Precambrian S-, I- and A-type granitoids in the Saldania belt, Western Cape Province, South Africa. J Afr Earth Sci 21:35–58
Scheepers R, Armstrong RA (2002) New U–Pb SHRIMP zircon ages of the Cape Granite Suite: implications for the magmatic evolution of the Saldania belt. S Afr J Geol 105:241–256
Scheepers R, Poujol M (2002) U–Pb zircon age of Cape Granite Suite ignimbrites: characteristics of the last phases of the Saldaniaan Magmatism. S Afr J Geol 105:163–178
Scherer E, Munker C, Mezger K (2001) Calibration of the Lutetium-Hafnium clock. Science 293:683–687
Scherer EE, Whitehouse MJ, Münker C (2007) Zircon as a monitor of crustal growth. Elements 3:19–24
Schoch AE, Leterrier J, De la Roche H (1977) Major element geochemical trends in the Cape Granites. Trans Geol Soc South Afr 80:197–209
Stevens G, Villaros A, Moyen J-F (2007) Selective peritectic garnet entrainment as the origin of geochemical diversity in S-type granites. Geology 35:9–12
Teixeira W, Cordani UG, Nutman AP, Sato K (1998) Polyphase Archean evolution in the Campo Belo metamorphic complex, Southern São Francisco Craton, Brazil: SHRIMP U–Pb zircon evidence. J South Am Earth Sci 11:279–289
Thirlwall MF, Anczkiewicz R (2004) Multidynamic isotope ratio analysis using MC–ICP-MS and the causes of secular drift in Hf, Nd and Pb isotope ratios. Int J Mass Spectrom 235:59–81
Van Achterbergh E, Ryan CG, Jackson SE, Griffin WL (2001) Data reduction software for LA-ICP-MS: appendix. In: Sylvester PJ (ed) Laser Ablation-ICP-mass spectrometry in the earth sciences: principles and applications, vol 29. Mineralog Assoc Canada (MAC) Short Course Series, Ottawa, Ontario, Canada, pp 239–243
Vervoort JD, Patchett PJ (1996) Behavior of hafnium and neodymium isotopes in the crust: constraints from Precambrian crustally derived granites. Geochim Cosmochim Acta 60:3717–3733
Vervoort JD, Patchett PJ, Albarède F, Blichert-Toft J, Rudnick R, Downes H (2000) Hf–Nd isotopic evolution of the lower crust. Earth Planet Sci Lett 181:115–129
Villaros A (2009) The Petrogenesis of S-type Cape Granite: in sight from source processes. Unpublished PhD Thesis, Stellenbosch University, South Africa
Villaros A, Stevens G, Buick IS (2009a) Tracking S-type granite from source to emplacement: clues from garnet in the Cape Granite Suite. Lithos 112:217–235
Villaros A, Stevens G, Moyen J-F, Buick IS (2009b) The trace element compositions of S-type granites: evidence for disequilibrium melting and accessory phase entrainment in the source. Contrib Mineral Petrol 158:543–561
Wang CY, Campbell IH, Allen CM, Williams IS, Eggins SM (2009) Rate of growth of the preserved North American continental crust: evidence from Hf and O isotopes in Mississippi detrital zircons. Geochim Cosmochim Acta 73:712–728
Watson EB, Harrison TM (1983) Zircon saturation revisited—temperature and composition effects in a variety of crustal magma types. Earth Planet Sci Lett 64:295–304
White AJR, Chappell BW (1977) Ultrametamorphism and granitoid genesis. Tectonophysics 43:7–22
Woodhead J, Hergt J (2005) A preliminary appraisal of seven natural zircon reference materials for in situ Hf isotope determination. Geostand Geoanal Res 29:183–195
Yang J-H, Wu F-Y, Wilde SA, Xie L-W, Yang Y-H, Liu X-M (2007) Tracing magma mixing in granite genesis: in situ U–Pb dating and Hf-isotope analysis of zircons. Contrib Mineral Petrol 153:177–190
Acknowledgments
The author want to thank Sarah Appleby for constructive reviewing and comments on this paper as well as Tim Grove for additional reviewing and editing of the manuscript. They also want to thank C. Allen, D. Rubatto, J. Hermann, (ANU). Malcolm McCulloch provided access to the LA-MC-ICP-MS, and Les Kingsley helped with its tuning and operation, and Steve Eggins provided an Excel spreadsheet for data reduction. This work forms part of a PhD study by AV. AV gratefully acknowledges an NRF PhD Bursary and support for the study via National Research Foundation grant funding to GS. ISB acknowledges support from an Australian Research Council Australian Professorial Fellowship and Discovery Grant No. DP0342473.
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Communicated by T. L. Grove.
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Villaros, A., Buick, I.S. & Stevens, G. Isotopic variations in S-type granites: an inheritance from a heterogeneous source?. Contrib Mineral Petrol 163, 243–257 (2012). https://doi.org/10.1007/s00410-011-0673-9
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DOI: https://doi.org/10.1007/s00410-011-0673-9