Skip to main content
SpringerLink
Log in

Independent ages of magmatic and hydrothermal activity in alkaline igneous rocks: The Motzfeldt Centre, Gardar Province, South Greenland

  • Original Paper
  • Published:
Contributions to Mineralogy and Petrology Aims and scope Submit manuscript

Abstract

The Motzfeldt Centre is one of four major alkaline centres belonging to the Igaliko complex, part of the Mid-Proterozoic Gardar province of South Greenland. Motzfeldt comprises syenites and nepheline syenites displaying complex magmatic and subsolidus histories. Ta, Nb and REE-rich zones are associated with a pervasive hydrothermal alteration process in the North and East of the complex, part of a subdivision of the Centre called the Motzfeldt Sø Formation (MSF). The zircons from the MSF show textures that are both magmatic and altered, whereas the textures of pyrochlore have a predominantly subsolidus chemistry. We compare and contrast the radiogenic isotope geochemistry of the zircon and pyrochlore to obtain independent age estimates of the magmatic and hydrothermal episodes. Selected analyses of magmatic zircons are concordant with an age of 1,273 ± 6 Ma. Altered zircons are normally discordant with one intercept at 1,261 ± 28 Ma and the other at 349 ± 49 Ma. This younger age would appear on face value to date the hydrothermal event at Motzfeldt to ~900 Ma after the magmatism. However, the Pb–Pb isotope systematics from altered pyrochlore define an isochron age of 1,267 ± 6 Ma for isotopic closure of the pyrochlore following alteration during the subsolidus. There is no known magmatic event in Southern Greenland at ~350 Ma and discordant points have high common lead. We therefore infer that the younger intercept age is spurious. The overlap between the magmatic U–Pb zircon and the Pb–Pb pyrochlore age suggests that alteration of the Motzfeldt centre occurred shortly after magmatism.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

References

  • Allaart JH (1976) Ketilidian mobile belt in South Greenland. In: Escher A, Watt SW (eds) Geology of Greenland. Geological Survey of Greenland, Denmark, pp 120–151

    Google Scholar 

  • Armour-Brown A (2001) Tantalum exploration: review of previous exploration, results of benefication studies and recommendations for future work, Angus & Ross plc report 1

  • Armour-Brown A, Tukiainen T, Wallin B, Bradshaw C, Emeleus CH (1983) Uranium exploration in South Greenland. Grønl Geol Unders Rap 115:68–75

    Google Scholar 

  • 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

    Article  Google Scholar 

  • Blaxland AB, van Breemen O, Emeleus CH, Anderson JG (1978) Age and origin of major syenite centers in Gardar Province of South Greenland—Rb-Sr studies. Geol Soc Am Bull 89:231–244

    Article  Google Scholar 

  • Bradshaw C (1985) The alkaline rocks of the Motzfeldt Centre: progress report on the 1984 field season. Grønl Geol Unders Rap 125:62–64

    Google Scholar 

  • Bradshaw C (1988) A petrographic, structural and geochemical study of the alkaline igneous rocks of the Motzfeldt Centre, South Greenland. PhD Thesis, University of Durham

  • Emeleus CH, Harry WT (1970) The Igaliko nepheline syenite complex. General description. Grønl Geol Unders Bull 85:116

    Google Scholar 

  • Finch AA (1995) Metasomatic overprinting by juvenile igneous fluids, Igdlerfigsalik, S Greenland. Contrib Mineral Petrol 122:11–24

    Article  Google Scholar 

  • Finch AA, Parsons I, Mingard SC (1995) Biotites as indicators of fluorine fugacities in late-stage magmatic fluids: the Gardar province of South Greenland. J Petrol 36:1701–1728

    Google Scholar 

  • Finch AA, Goodenough KM, Salmon HM, Andersen T (2001a) The petrology and petrogenesis of the North Motzfeldt centre, Gardar Province, South Greenland. Min Mag 65:759–774

    Article  Google Scholar 

  • Finch AA, Mansfeld J, Andersen T (2001b) U–Pb radiometric age of Nunarsuit pegmatite, Greenland: constraints on the timing of Gardar magmatism. Bull Geol Soc Den 48:1–7

    Google Scholar 

  • Garde AA, Chadwick B, Grocott J, Hamilton MA, McCaffrey KJW, Swager CP (2002) Mid-crustal partitioning and attachment during oblique convergence in an arc system, the Palaeoproterozoic Ketilidian orogen, southern Greenland. J Geol Soc Lond 159:247–261

    Article  Google Scholar 

  • Geisler T, Pidgeon RT, Van Bronswijk W, Kurtz R (2002) Transport of uranium, thorium, and lead in metamict zircon under low-temperature hydrothermal conditions. Chem Geol 191:141–154

    Article  Google Scholar 

  • Geisler T, Schaltegger U, Tomaschek F (2007) Re-equilibration of zircon in aqueous fluids and melts. Elements 3:43–50

    Article  Google Scholar 

  • Gilotti JA, McClelland WC (2008) Geometry, kinematics and timing of extensional faulting in the Greenland Caledonides–a synthesis. In: Higgins AK, Gilotti JA, Smith MP (eds) The Greenland Caledonides: evolution of the northeast margin of Laurentia. Geological Society of America Memoir 202:251–271

  • Goodenough KM, Upton BGJ, Ellam RM (2000) Geochemical evolution of the Ivigtut granite, South Greenland: a fluorine-rich “A-type” intrusion. Lithos 51:205–221

    Article  Google Scholar 

  • Hansen BT, Friderichsen JD (1989) The influence of recent lead loss on the interpretation of disturbed U–Pb systems in zircons from igneous rocks in East Greenland. Lithos 23:209–223

    Article  Google Scholar 

  • Harley S, Kelly N (2007) Zircon: tiny but timely. Elements 3:13–18

    Article  Google Scholar 

  • Henriksen N, Higgins AK (2008) Caledonian orogen of East Greenland 70°N–82°N: geological map at 1:1 000 000–concepts and principles of compilation. In: Higgins AK, Gilotti JA, Smith MP (eds) The Greenland Caledonides: evolution of the northeast margin of Laurentia. Geological Society of America Memoir 202:345–368

  • Hogarth DD (1977) Classification and nomenclature of the pyrochlore group. Am Mineral 35:403–410

    Google Scholar 

  • Hoskin PWO, Ireland TR (2000) Rare earth element chemistry of zircon and its uses as a provenance indicator. Geology 28:627–630

    Article  Google Scholar 

  • 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 211:47–69

    Article  Google Scholar 

  • Jones AP (1980) The petrology and structure of the Motzfeldt centre, Igaliko, South Greenland, PhD Thesis, University of Durham, UK

  • Keppler H, Wyllie PJ (1990) Role of fluids in transport and fractionation of uranium and thorium in magmatic processes. Nature 348:531–533

    Article  Google Scholar 

  • Leslie AG, Higgins AK (2008) Foreland-propagating Caledonian thrust systems in East Greenland. In: Higgins AK, Gilotti JA, Smith MP (eds) The Greenland Caledonides: evolution of the northeast margin of Laurentia. Geological Society of America Memoir 202:169–199

  • Liégeois J-P, Benhallou M, Azzouni-Sekkal A, Yahiaoui R, Bonin B (2005) The Hoggar swell and volcanism: reactivation of the Precambrian Tuareg shield during Alpine convergence and West African Cenozoic volcanism. Geological Society of America Special Paper 388:379–400

    Google Scholar 

  • Ludwig KR (2003) User’s manual for Isoplot 3.00. A geochronological toolkit for Microsoft Excel. Berkley Geochronology Centre Special Publication, 4a

  • Lumpkin GR, Ewing RC (1992) Geochemical alteration of pyrochlore group minerals—microlite subgroup. Am Mineral 77:179–188

    Google Scholar 

  • Lumpkin GR, Ewing RC (1995) Geochemical alteration of pyrochlore group minerals—pyrochlore subgroup. Am Mineral 80:732–743

    Google Scholar 

  • McCreath JA (2009) Petrology and petrogenesis of the Motzfeldt Ta-mineralisation, Gardar Province, South Greenland. Unpubl. PhD thesis, University of St Andrews, UK

  • Patchett J, Kouvo O (1986) Origin of continental-crust of 1.9–1.7 Ga age—Nd isotopes and U–Pb zircon ages in the Svecokarelian terrain of South Finland. Contrib Mineral Petrol 92:1–12

    Article  Google Scholar 

  • Pidgeon RT (1992) Recrystallization of oscillatory zoned zircon—some geochronological and petrological implications. Contrib Mineral Petrol 110:463–472

    Article  Google Scholar 

  • Pidgeon RT, Nemchin AA, Hitchen GJ (1998) Internal structures of zircons from Archaean granites from the Darling Range batholith: implications for zircon stability and the interpretation of zircon U–Pb ages. Contrib Mineral Petrol 132:288–299

    Article  Google Scholar 

  • Simonetti A, Heaman LM, Hartlaub RP, Creaser RA, MacHattie TG, Böhm C (2005) U–Pb zircon dating by laser ablation-MC-ICP-MS using a new multiple ion counting Faraday collector array. J Anal At Spectrom 20:677–686

    Article  Google Scholar 

  • Sinha AK, Wayne DM, Hewitt DA (1992) The hydrothermal stability of zircon—preliminary experimental and isotopic studies. Geochim Cosmochim Acta 56:3551–3560

    Article  Google Scholar 

  • Soman A, Geisler T, Tomaschek F, Grange M, Berndt J (2010) Alteration of crystalline zircon solid solutions: a case study on zircon from an alkaline pegmatite from Zomba-Malosa, Malawi. Contribs Mineral Petrol 160:909–930

    Article  Google Scholar 

  • Steiger RH, Jäger E (1977) Convention on the use of decay constants in geo- and cosmochronology. Earth Planet Sci Lett 36:359–362

    Article  Google Scholar 

  • Stephenson D (1976) A simple-shear model for the ductile deformation of high-level intrusions in South Greenland. J Geol Soc Lond 132:307–318

    Article  Google Scholar 

  • Tilton G (1960) Volume diffusion as a mechanism for discordant lead ages. J Geophys Res 65:2933–2945

    Article  Google Scholar 

  • Tukiainen T (1988) Niobium-tantalum mineralisation in the Motzfeldt centre of the Igaliko nepheline syenite complex, South Greenland. In: Boissonnas J, Omenetto P (eds) Mineral deposits within the European community. Springer, Berlin, pp 230–246

    Google Scholar 

  • Tukiainen T, Bradshaw C, Emeleus CH (1984) Geological and radiometric mapping of the Motzfeldt Centre of the Igaliko Complex, South Greenland. Grønl Geol Unders Rap 102:78–83

    Google Scholar 

  • Upton BGJ, Blundell DJ (1978) The Gardar Igneous province: evidence for proterozoic continental rifting. In: Neumann ER, Ramberg IB (eds) Petrology and geochemistry of continental rifts. Reidel, Dordrecht, pp 163–172

    Google Scholar 

  • Upton BGJ, Emeleus CH (1987) Mid-Proterozoic alkaline magmatism in Southern Greenland: the Gardar Province. In: Fitton JG, Upton BGJ (eds) Alkaline igneous rocks special publication. Geological Society of London, London, pp 449–471

    Google Scholar 

  • Upton BGJ, Emeleus CH, Heaman LM, Goodenough KM, Finch AA (2003) Magmatism of the mid-Proterozoic Gardar Province, South Greenland: chronology, petrogenesis and geological setting. Lithos 68:43–65

    Article  Google Scholar 

  • Van Achterbergh AE, Griffin WL, Kivi K, Pearson NJ, O’Reilly SY (2001) Carbonatites at 200 km: quenched melt inclusions in megacrystalline Iherzolite xenoliths, Slave Craton, Canada. J Afr Earth Sci 32:A35

    Google Scholar 

  • 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

    Article  Google Scholar 

  • Wetherill G (1956) Discordant uranium-lead ages, I. Trans Am Geophys Union 37:320–326

    Google Scholar 

  • Wetherill G (1963) Discordant uranium-lead ages—Part 2: discordant ages resulting from diffusion of lead and uranium. J Geophys Res 68:2957–2965

    Article  Google Scholar 

  • Wiedenbeck M, Alle P, Corfu F, Griffin WL, Meier M, Oberli F, Von Quadt A, Roddick JC, Spiegel W (1995) Three natural zircon standards for U–Th–Pb, Lu–Hf, trace element and REE analyses. Geostand Newsl 19:1–23

    Article  Google Scholar 

Download references

Acknowledgments

Work for the present study was carried out during tenure of a postgraduate studentship funded by Angus and Ross plc. The assistance of Tom Andersen with isotopic determinations is gratefully acknowledged. Field assistance was provided by Johannes Schönenberger, Teal Riley and Malcolm Wilkinson. The manuscript was greatly improved by detailed and constructive comments from Kathryn Goodenough and Jean-Pierre Liégeois. The present manuscript is contribution no. 26 from the Isotope Geology Laboratory at the University of Oslo.

Author information

Author notes

  1. J. A. McCreath

    Present address: Red Rock Resources plc, 115 Eastbourne Mews, London, W2 6LQ, UK

Authors and Affiliations

  1. Centre for Earth Resources St Andrews (CERSA) and Department of Earth Sciences, University of St Andrews, St Andrews, Fife, KY16 9AL, UK

    J. A. McCreath, A. A. Finch & C. H. Donaldson

  2. Laboratory of Isotope Geology, Department of Geosciences, University of Oslo, Sem Sælands vei 1, Oslo, 0316, Norway

    S. L. Simonsen

  3. Angus and Ross plc, Kirkbymoorside, York, UK

    A. Armour-Brown

Authors
  1. J. A. McCreath
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. A. A. Finch
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. S. L. Simonsen
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. C. H. Donaldson
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. A. Armour-Brown
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to A. A. Finch.

Additional information

Communicated by J. Blundy.

Electronic supplementary material

Rights and permissions

Reprints and permissions

About this article

Cite this article

McCreath, J.A., Finch, A.A., Simonsen, S.L. et al. Independent ages of magmatic and hydrothermal activity in alkaline igneous rocks: The Motzfeldt Centre, Gardar Province, South Greenland. Contrib Mineral Petrol 163, 967–982 (2012). https://doi.org/10.1007/s00410-011-0709-1

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00410-011-0709-1

Keywords

Search

Navigation