Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-13T02:59:47.531Z Has data issue: false hasContentIssue false

Granite genesis and the mechanics of convergent orogenic belts with application to the southern Adelaide Fold Belt

Published online by Cambridge University Press:  03 November 2011

Mike Sandiford
Affiliation:
Mike Sandiford, John Foden, Shaohua Zhou and Simon Turner, Department of Geology and Geophysics,University of Adelaide, G.P.O. Box 498, Adelaide, South Australia 5001, Australia

Abstract

Two models for the heating responsible for granite generation during convergent deformation may be distinguished on the basis of the length- and time-scales associated with the thermal perturbation, namely: (1) long-lived, lithospheric-scale heating as a conductive response to the deformation, and (2) transient, localised heating as a response to advective heat sources such as mantle-derived melts. The strong temperature dependence of lithospheric rheology implies that the heat advected within rising granites may affect the distribution and rates of deformation within the developing orogen in a way that reflects the thermal regime attendant on granite formation; this contention is supported by numerical models of lithospheric deformation based on the thin-sheet approximation. The model results are compared with geological and isotopic constraints on granite genesis in the southern Adelaide Fold Belt where intrusion spans a 25 Ma convergent deformation cycle, from about 516 to 490 Ma, resulting in crustal thickening to 50–55 km. High-T metamorphism in this belt is spatially restricted to an axis of magmatic activity where the intensity and complexity of deformation is significantly greater, and may have started earlier, than in adjacent low-grade areas. The implication is that granite generation and emplacement is a causative factor in localising deformation, and on the basis of the results of the mechanical models suggests that granite formation occurred in response to localised, transient crustal heating by mantle melts. This is consistent with the Nd- and Sr-isotopic composition of the granites which seems to reflect mixed sources with components derived both from the depleted contemporary mantle and the older crust.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Arculus, R. J., Ferguson, J., Chapell, B. W., Smith, D., McCulloch, M. T., Jackson, I., Hensel, H. D., Taylor, S. R., Knutson, J. & Gust, D. A. 1990. Eclogites and granultes in the lower continental crust: examples from eastern Australia and southwestern USA. In Smith, D. C. (ed) Eclogites and related rocks, 335–80. Amsterdam: Elsevier.Google Scholar
Bird, P. 1991. Lateral extrusion of lower crust from under high topography in the isostatic limit. J GEOPHYS RES 96, 10, 275–86.Google Scholar
Bird, P. & Piper, K. 1980. Plane stress finite element modes of tectonic flow in southern California. PHYS EARTH PLANET INT 21, 158–75.CrossRefGoogle Scholar
Brace, W. F. & Kholstedt, D. L. 1980. Limits on lithospheric stress imposed by laboratory experiments J GEOPHYS RES 85, 6248–52.CrossRefGoogle Scholar
Byrlee, J. D. 1968. Brittle-ductile transition in rocks J GEOPHYS RES 73, 4741–50.CrossRefGoogle Scholar
Collins, W. J. & Vernon, R. H. 1991. Orogeny associated with anticlockwise P-T-t paths:evidence from low-P,high-T terranes in the Arunta Inlier, central Australia. GEOLOGY (in press).2.3.CO;2>CrossRefGoogle Scholar
Cooper, J. A., Jenkins, R. J. F., Compston, W. & Williams, I. S. 1990. Ion microprobe U-Pb zircon dating within the lower Cambrian of South Australia. GEOL SOC AUST ABSTR 27, 96.Google Scholar
Crawford, A. J. & Hilyard, D. 1990. Geochemistry of Late Proterozoic tholeiitic flood basalts, Adelaide Geosyncline, South Australia. GEOL SOC AUST SPEC PUBL 16, 4967.Google Scholar
DePaolo, D. 1981. Trace element and isotopic effects of combined wallrock assimilation and fractional crystallisation. EARTH PLANET SCI LETT 53, 189202.CrossRefGoogle Scholar
Dymoke, P. & Sandiford, M. 1992. Phase relationships in Buchan Facies Series pelitic assemblages: Calculations with application to andalusite-staurolite parageneses in the Mount Lofty Ranges, South Australia. CONTRIB MINERAL PETROL (in press).CrossRefGoogle Scholar
England, P. C. 1987. Diffuse deformation: length scales, rates and metamorphic evolution. PHILOS TRANS R SOC LONDON A321, 322.Google Scholar
England, P. C. & Jackson, J. 1989. Active deformation of the continents. ANN REV EARTH PLANET SCI 17, 197226.CrossRefGoogle Scholar
Fleming, P. D. & White, A. J. R. 1984. Relationships between deformation and partial melting in the Palmer migmatites. AUST J EARTH SCI 31, 351–60.CrossRefGoogle Scholar
Foden, J. D., Turner, S. P. & Morrison, R. S. 1990. The tectonic implications of Delamerian magmatism in South Australia and western Victoria. GEOL SOC AUST SPEC PUBL 16, 465–82.Google Scholar
Foden, J. D., Williams, I., Compston, W., Michard, A. & Turner, S. P. in prep. Some constraints on the timing of the Delamerian Orogeny in the Southern Adelaide Fold Belt: Implications for the evolution of the eastern margin of Gondwanaland (in prep.).Google Scholar
Gans, P. B. 1987. An open-system, two-layer crustal stretching model for the eastern Great basin. TECTONICS 6, 112.CrossRefGoogle Scholar
Greenhalgh, S. A., Tapley, D. & von der Borch, C. C. 1991. Explosion seismic determination of crustal structure beneath the Adelaide Geosyncline, South Australia. PHYS EARTH PLANET INT 58, 323–43.CrossRefGoogle Scholar
Griffin, W. L., O'Reilly, S. Y. & Stabel, A. 1988. Mantle metasomatism beneath western Victoria, Australia: II. Isotopic geochemistry of Cr-diopside lherzolites and Al-augite pyroxenites. GEOCHIM COSMOCHIM ACTA 52, 449–59.CrossRefGoogle Scholar
Hildreth, W. & Moorbath, S. 1988. Crustal contributions to arc magmatism in the Andes of Central Chile. CONTRIB MINERAL PETROL 98, 455–89.CrossRefGoogle Scholar
Houseman, G. A., McKenzie, D. P. & Molnar, P. 1981. Convective instability of a thickened boundary layer and its relevance for the thermal evolution of continental convergent belts. J GEOPHYS RES 86, 6115–32.CrossRefGoogle Scholar
Huppert, H. E. & Sparks, R. S. J. 1988. The generation of granitic magmas by intrusion of basalt into continental crust. J PETROL 29, 599624.CrossRefGoogle Scholar
Jaoul, O., Tullis, J. & Kronenberg, A. 1984. The effect of varying water contents on the creep behaviour of Heavitree Quartzite. J GEOPHYS RES 89, 4298–312.CrossRefGoogle Scholar
Jenkins, R. J. F. 1990. The Adelaide Foldbelt: tectonic reappraisal. GEOL SOC AUST SPEC PUBL 16, 396420.Google Scholar
Mancktelow, N. S. 1990. The structure of the southern Adelaide Fold Belt, south Australia. GEOL SOC AUST SPEC PUBL 16, 369–95.Google Scholar
McCulloch, M. T., Arculus, R. J., Chappell, B. W. & Ferguson, J. 1982. Isotopic and geochemical studies of nodules in kimberlite have implications for the lower continental crust. NATURE 300, 166–9.CrossRefGoogle Scholar
McDonough, W. F., McCulloch, M. T. & Sun, S. S. 1985. Isotopic and geochemical systematics in Tertiary-Recent basalts from southeastern Australia and implications for the evolution of the subcontinental lithosphere. GEOCHIM COSMOCHIM ACTA 49, 2051–67.CrossRefGoogle Scholar
McDonough, W. F. & McCulloch, M. T. 1987. The southeast Australian lithospheric mantle: isotopic and geochemical constraints on its growth and evolution. EARTH PLANET SCI LETT 86, 327–40.CrossRefGoogle Scholar
Miller, E. L. & Gans, P. B. 1989. Cretaceous crustal structure and metamorphism in the hinterland of the Sevier thrust belt. GEOLOGY 17, 5962.2.3.CO;2>CrossRefGoogle Scholar
Milnes, A. R., Compston, W. & Daily, B. 1977. Pre- to syn-tectonic emplacement of early Palaeozoic granites in southeastern South Australia. J GEOL SOC AUST 24, 87106.CrossRefGoogle Scholar
Molnar, P. & Lyon-Caen, H. 1988. Some simple physical aspects of the support, structure, and evolution of mountain belts. GEOL SOC AM SPEC PAP 218, 179207.Google Scholar
Offler, R. & Fleming, P. D. 1968. A synthesis of folding and metamorphism in the Mt Lofty Ranges, South Australia. J GEOL SOC AUST 15, 245–66.CrossRefGoogle Scholar
Ord, A. & Hobbs, B. E. 1989. The strength of the continental crust. TECTONOPHYSICS 158, 269–89.CrossRefGoogle Scholar
O'Reilly, S. Y. & Griffin, W. L. 1988. Mantle metasomatism beneath western Victoria, Australia: I. Metasomatic processes in Cr-diopside lherzolites. GEOCHIM COSMOCHIM ACTA 52, 443–47.CrossRefGoogle Scholar
Patterson, M. S. 1987. Problems in extrapolation of laboratory Theological data. TECTONOPHYSICS 133, 3343.CrossRefGoogle Scholar
Preiss, W. V. 1987. The Adelaide Geosyncline: Late Proterozoic stratigraphy, sedimentation, palaeontology and tectonics. BULL GEOL SURV S AUST 53.Google Scholar
Sandiford, M., Oliver, R. L., Mills, K. J. & Allen, R. V. 1990. A cordierite-staurolite-muscovite association, east of Springton, Mt Lofty Ranges; implications for the metamorphic evolution of the Kanmantoo Group. GEOL SOC AUST SPEC PUBL 16, 483–95.Google Scholar
Sandiford, M., Martin, N., Zhou, S. and Fraser, G. 1991. Mechanical consequences of granite emplacement during high-T, low-P metamorphism and the origin of ‘anticlockwise’ PT paths. EARTH PLANET SCI LETT 107, 164–72.CrossRefGoogle Scholar
Sandiford, M. & Powell, R. 1990. Some isostatic and thermal consequences of the vertical strain geometry in convergent orogens. EARTH PLANET SCI LETT 98, 154–65.CrossRefGoogle Scholar
Sandiford, M. & Powell, R. 1991. Isostatic and thermal constraints on the evolution of high temperature low pressure metamorphic terrains in convergent orogens. J METAMORPH GEOL 9, 333–40.CrossRefGoogle Scholar
Sonder, L. J., England, P. C., Wernicke, B. P. & Christiansen, R. L. 1987. A physical model for Cenozoic extension of western North America. In Coward, M. P., Dewey, J. F. & Hancock, P. L. (eds) Continental Extensional Tectonics. GEOL SOC LONDON SPEC PUBL 28, 187201.CrossRefGoogle Scholar
Sonder, L. J. & England, P. 1986. Vertical averages of rheology of the continental lithosphere: relation to thin sheet parameters. EARTH PLANET SCI LETT 77, 8190.CrossRefGoogle Scholar
Thompson, P. 1989. Moderate over-thickening of thinned sialic crust and the origin of granitic magmatism and regional metamorphism in low-P-high-T terranes. GEOLOGY 17, 520–23.2.3.CO;2>CrossRefGoogle Scholar
Turner, S. P., Foden, J. D. & Morrison, R. 1992. Derivation of A-type magma by fractionation of basaltic magma and an example from the Padthaway Ridge, South Australia. LITHOS (in press).CrossRefGoogle Scholar
Turner, S. P. & Foden, J. D. 1990. The nature of mafic magmatism through the evolution of the Adelaide Foldbelt and subsequent Delamerian Orogeny. In Parker, J. (ed) Mafic dykes and emplacement mechanisms. Rotterdam: Balkema, 431–5.Google Scholar
Zhou, S. & Sandiford, M. 1991. On the stability of isostatically compensated mountain belts. J GEOPHYS RES (submitted).CrossRefGoogle Scholar