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Compositional variation within granite suites of the Lachlan Fold Belt: its causes and implications for the physical state of granite magma

Published online by Cambridge University Press:  03 November 2011

B. W. Chappell
B. W. Chappell
Affiliation:
B. W. Chappell, Key Centre in Geochemistry and Metallogeny of the Continents (GEMOC), Department of Geology.The Australian National University, Canberra, ACT 0200, Australia.
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Abstract:

Granites within suites share compositional properties that reflect features of their source rocks. Variation within suites results dominantly from crystal fractionation, either of restite crystals entrained from the source, or by the fractional crystallisation of precipitated crystals. At least in the Lachlan Fold Belt, the processes of magma mixing, assimilation or hydrothermal alteration were insignificant in producing the major compositional variations within suites. Fractional crystallisation produced the complete variation in only one significant group of rocks of that area, the relatively high temperature Boggy Plain Supersuite. Modelling of Sr, Ba and Rb variations in the I-type Glenbog and Moruya suites and the S-type Bullenbalong Suite shows that variation within those suites cannot be the result of fractional crystallisation, but can be readily accounted for by restite fractionation. Direct evidence for the dominance of restite fractionation includes the close chemical equivalence of some plutonic and volcanic rocks, the presence of plagioclase cores that were not derived from a mingled mafic component, and the occurrence of older cores in many zircon crystals. In the Lachlan Fold Belt, granite suites typically evolved through a protracted phase of restite fractionation, with a brief episode of fractional crystallisation sometimes evident in the most felsic rocks. Evolution of the S-type Koetong Suite passed at about 69% SiO2 from a stage dominated by restite separation to one of fractional crystallisation. Other suites exist where felsic rocks evolved in the same way, but the more mafic rocks are absent. In terranes in which tonalitic rocks formed at high temperatures are more common, fractional crystallisation would be a more important process than was the case for the Lachlan Fold Belt.

Keywords

assimilationcrystal fractionationfractional crystallisationgranite suiteshybridsmagmasmagma minglingmagma mixingpartition coefficientsrestitesrestite fractionation
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 87 , Issue 1-2: Third Hutton Symposium. The Origin of Ganites and Related Rocks , 1996 , pp. 159 - 170
Copyright
Copyright © Royal Society of Edinburgh 1996

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References

Baker, G. 1940. Cordierite granite from Terip Terip, Victoria. AM MINERAL 25, 543–8.Google Scholar
Barbarin, B. 1991. Enclaves of the Mesozoic calc-alkaline granitoids of the Sierra Nevada Batholith, California. In Didier, J.&Barbarin, B. (eds) Enclaves and Granite Petrology, 135–53. Amsterdam: Elsevier.Google Scholar
Beams, S. D. 1980. Magmatic evolution of the Southeast Lachlan Fold Belt, Australia. Ph.D. Thesis, La Trobe University, Melbourne.Google Scholar
Blevin, P. L.&Chappell, B. W. 1992. The role of magma sources, oxidation states and fractionation in determining the granite metallogeny of eastern Australia. TRANS R SOC EDINBURGH EARTH SCI 83, 305–16.Google Scholar
Blundy, J. D.&Wood, B. J. 1991. Crystal-chemical controls on the partitioning of Sr and Ba between plagioclase feldspar, silicate melts, and hydrothermal solutions. GEOCHIM COSMOCHIM ACTA 55, 193–209.CrossRefGoogle Scholar
Bowen, N. L. 1928. The Evolution of the Igneous Rocks. Princeton: Princeton University Press.Google Scholar
Chappell, B. W. 1979. Granites as images of their source rocks. GEOL SOC AM ABSTR PROGRAM 11, 400.Google Scholar
Chappell, B. W. 1996. Magma mixing and the production of compositional variation within granite suites: evidence from the granites of southeastern Australia. J PETROL 37.CrossRefGoogle Scholar
Chappell, B. W.&McCulloch, M. T. 1990. Possible mixed source rocks in the Bega Batholith: constraints provided by combined chemical and isotopic studies. GEOL SOC AUST ABSTR 27, 17.Google Scholar
Chappell, B. W.&Stephens, W. E. 1988. Origin of infracrustal (I-type) granite magmas. TRANS R SOC EDINBURGH EARTH SCI 79, 71–86.Google Scholar
Chappell, B. W.&White, A. J. R. 1992. I- and S-type granites in the Lachlan Fold Belt. TRANS R SOC EDINBURGH EARTH SCI 83, 1–26.Google Scholar
Chappell, B. W., White, A. J. R.&Wyborn, D. 1987. The importance of residual source material (restite) in granite petrogenesis. J PETROL 28, 1111–38.CrossRefGoogle Scholar
Chappell, B. W., Williams, I. S., White, A. J. R.&McCulloch, M. T. 1990. Granites of the Lachlan Fold Belt. ICOG 7 Field Guide Excursion A-2. REC BMR GEOL GEOPHYS 1990/48.Google Scholar
Clemens, J. D.&Mawer, C. K. 1992. Granitic magma transport by fracture propagation. TECTONOPHYSICS 204, 339–60.CrossRefGoogle Scholar
Collins, W. J. 1995. S- and I-type granitoids of the eastern Lachlan Fold Belt: three-component mixing, not restite unmixing. In Brown, M.&Piccoli, P. M. (eds) The Origin of Granites and Related Rocks. Third Hutton Symposium Abstracts. US GEOL SURV CIRC 1129, 37–8.Google Scholar
Compston, W.&Chappell, B. W. 1979. Sr-isotope evolution of granitoid source rocks. In McElhinny, M. W. (ed.) The Earth: its Origin, Structure and Evolution, 377–426. London: Academic Press.Google Scholar
DePaolo, D. J. 1981a. Trace element and isotopic effects of combined wallrock assimilation and fractional crystallization. EARTH PLANET SCI LETT 53, 189–202.CrossRefGoogle Scholar
DePaolo, D. J. 1981b. A neodymium and strontium isotopic study of the Mesozoic calc-alkaline granitic batholiths of the Sierra Nevada and Peninsular Ranges, California. J GEOPHYS RES 86, 10470–88.CrossRefGoogle Scholar
Gray, C. M. 1984. An isotopic mixing model for the origin of granitic rocks in southeastern Australia. EARTH PLANET SCI LETT 70, 47–60.CrossRefGoogle Scholar
Grout, F. F. 1948. Origin of granite. In Gilluly, J. (ed.) Origin of Granite. GEOL SOC AM MEM 28, 45–54.Google Scholar
Hine, R., Williams, I. S., Chappell, B. W.&White, A. J. R. 1978. Contrasts between I- and S-type granitoids of the Kosciusko Batholith. J GEOL SOC AUST 25, 219–34.CrossRefGoogle Scholar
Johannes, W. 1978. Melting of plagioclase in the system Ab–An–H2O and Qz–Ab–An–H2O at P H2O = 5 kbars, an equilibrium problem. CONTRIB MINERAL PETROL 66, 295–303.CrossRefGoogle Scholar
McCulloch, M. T.&Chappell, B. W. 1982. Nd isotopic characteristics of S- and I-type granites. EARTH PLANET SCI LETT 58, 51–64.CrossRefGoogle Scholar
McCulloch, M. T., Chappell, B. W.&Hensel, H. D. 1982. Nd and Sr isotope relations in granitic rocks of the Tasman Fold Belt, eastern Australia. ABST ICOG 5, 246–7.Google Scholar
Munksgaard, N. C. 1988. Source of the Cooma Granodiorite, New South Wales—a possible role of fluid–rock interactions. AUST J EARTH SCI 35, 363–77.CrossRefGoogle Scholar
Pidgeon, R. T.&Compston, W. 1992. A SHRIMP ion microprobe study of inherited and magmatic zircons from four Scottish Caledonian granites. TRANS R SOC EDINBURGH EARTH SCI 83, 473–83.Google Scholar
Pitcher, W. S. 1982. Granite type and tectonic environment. In Hsu, K. J. (ed.) Mountain Building Processes, 19–40. London: Academic Press.Google Scholar
Pitcher, W. S. 1993. The Nature and Origin of Granite. Glasgow: Blackie Academic & Professional.CrossRefGoogle Scholar
Read, H. H. 1948. Granites and granites. In Gilluly, J. (ed.) Origin of Granite. GEOL SOC AM MEM 28, 1–19.Google Scholar
Rushmer, T. 1995. An experimental deformation study of partially molten amphibolite: application to low melt fraction segregation. J GEOPHYS RES 100, 15 681–95.Google Scholar
Shand, S. J. 1950. Eruptive Rocks, 4th edn. London: Murby.Google Scholar
Sparks, R. S. J.&Marshall, L. A. 1986. Thermal and mechanical constraints on mixing between mafic and silicic magmas. J VOLCANOL GEOTHERM RES 29, 99–124.CrossRefGoogle Scholar
Stevens, N. C. 1952. The petrology of the Cowra intrusion and associated xenoliths. PROC LINN SOC NSW 77, 132–41.Google Scholar
Tuttle, O. F.&Bowen, N. L. 1958. Origin of granite in the light of experimental studies in the system NaAlSi3O8–KAlSi3O8–SiO2–H2O. GEOL SOC AM MEM 74.Google Scholar
van der Molen, I.&Paterson, M. S. 1979. Experimental deformation of partially-melted granite. CONTRIB MINERAL PETROL 70, 299–318.CrossRefGoogle Scholar
Wall, V. J., Clemens, J. D.&Clarke, D. B. 1987. Models for granitoid evolution and source compositions. J GEOL 95, 731–49.CrossRefGoogle Scholar
White, A. J. R. 1995. Suite concept in igneous geology. In Leon T. Silver 70th Birthday Symposium and Celebration. 113–6. The California Institute of Technology.Google Scholar
White, A. J. R.&Chappell, B. W. 1988. Some supracrustal (S-type) granites of the Lachlan Fold Belt. TRANS R SOC EDINBURGH EARTH SCI 79, 169–81.Google Scholar
Williams, I. S. 1992. Some observations on the use of zircon U–Pb geochronology in the study of granitic rocks. TRANS R SOC EDINBURGH EARTH SCI 83, 447–58.Google Scholar
Williams, I. S. 1995. Zircon analysis by ion microprobe: the case of the eastern Australian granites. In Leon T. Silver 70th Birthday Symposium and Celebration 27–31. The California Institute of Technology.Google Scholar
Wyborn, D. 1983. Fractionation processes in the Boggy Plain zoned pluton. Ph.D. Thesis, The Australian National University, Canberra.Google Scholar
Wyborn, D.&Chappell, B. W. 1986. The petrogenetic significance of chemically related plutonic and volcanic rock units. GEOL MAG 123, 619–28.CrossRefGoogle Scholar
Wyborn, D., Chappell, B. W.&Johnston, R. M. 1981. Three S-type volcanic suites from the Lachlan Fold Belt, southeast Australia. J GEOPHYS RES 86, 10 335–48.Google Scholar
Wyborn, D., Turner, B. S.&Chappell, B. W. 1987. The Boggy Plain Supersuite: a distinctive belt of I-type igneous rocks of potential economic significance in the Lachlan Fold Belt. AUST J EARTH SCI 34, 21–43.CrossRefGoogle Scholar
Wyborn, L. A. I.&Chappell, B. W. 1983. Chemistry of the Ordovician and Silurian greywackes of the Snowy Mountains, southeastern Australia: an example of chemical evolution of sediments with time. CHEM GEOL 39, 81–92.CrossRefGoogle Scholar