Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-24T12:27:53.562Z Has data issue: false hasContentIssue false
  • English
  • Français

Melt movement and the occlusion of porosity in crystallizing granitic systems

Published online by Cambridge University Press:  05 July 2018

D. N. Bryon ,
M. P. Atherton ,
M. J. Cheadle  and
R. H. Hunter
D. N. Bryon
Affiliation:
Department of Earth Sciences, University of Liverpool, Liverpool, L69 3BX, UK
M. P. Atherton
Affiliation:
Department of Earth Sciences, University of Liverpool, Liverpool, L69 3BX, UK
M. J. Cheadle
Affiliation:
Department of Earth Sciences, University of Liverpool, Liverpool, L69 3BX, UK
R. H. Hunter
Affiliation:
Department of Earth Sciences, University of Liverpool, Liverpool, L69 3BX, UK
Get access Rights & Permissions [Opens in a new window]

Abstract

Porosity occlusion has been studied in a granodiorite rock from the Peruvian Coastal Batholith. The texture of the granodiorite is characteristic of Cordilleran I-type rocks, and the textural relations and modelled crystallization path within the quaternary An-Ab-Or-Qz system indicate alkali feldspar was the last major phase to start crystallizing. In thin section, alkali feldspar crystals occur both as large anhedral ‘plates’ containing numerous inclusions, and small interstitial cuneiform ‘pockets’. The alkali feldspar pockets are interpreted as late stage nucleation and growth of new crystals in pores that became isolated from the larger crystals during the latter stages of crystallization. Their geometry therefore mirrors that of the pores immediately after isolation.

From the modal abundance of the interstitial pockets, and taking into account contemporaneous growth of the other major phases, it is suggested that crystallization in isolated pores involved solidification of the final 3–4% of liquid. Alkali feldspar growth on the rims of the large anhedral plates prior to pore isolation is evidence for the localised (mm-cm scale) diffusion of chemical species within the interconnected melt phase. However, Rayleigh number calculations indicate that the separation of melt from crystals by compositional convection is unlikely to have occurred during interstitial crystallization.

Keywords

granitetextural developmentporosity occlusioncompositional convection
Type
The 1995 Hallimond Lecture
Information
Mineralogical Magazine , Volume 60 , Issue 398 , February 1996 , pp. 163 - 171
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1996

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

Atherton, M.P. and Sanderson, L.M. (1985) The chemical variation and evolution of the superunits of the segmented Coastal Batholith. In Magmatism at a plate edge: the Peruvian Andes.(Pitcher, W.S., Atherton, M.P., Cobbing, E.J. and Beckinsale, R.D., eds.). Blackie, Halstead Press, Glasgow, pp 108—18.Google Scholar
Beere, W. (1975) A unifying theory of the stability of penetrating liquid phases and sintering pores. Acta Metallurgical, 23, 131–8.CrossRefGoogle Scholar
Bottinga, Y., Richet, P. and Weill, D.F. (1983) Calculation of the density and thermal expansion coefficient of silicate liquids. Bull. Mineral., 106, 129–38.Google Scholar
Bryon, D.N. (1992) Textural development in granitoid rocks: a case study from the zoned Linga superunit of the Coastal Batholith, Peru.Unpubl. PhD thesis, Univ. of Liverpool.Google Scholar
Bryon, D.N., Atherton, M.P. and Hunter, R.H. (1994) The description of the primary textures of Cordilleran granitic rocks. Contrib. Mineral. 117, 66—75.CrossRefGoogle Scholar
Bryon, D.N., Atherton, M.P. and Hunter, R.H. (1995) The interpretation of granitic textures from serial thin sectioning, image analysis and three-dimensional reconstruction. Mineral Mag., 59, 203–11.CrossRefGoogle Scholar
Bulau, J.R., Waff, H. and Tyburczy, J.A. (1979) Mechanical and thermodynamic constraints of fluid distribution in partial melts. J. Geophys. Res., 84, 6102–8.CrossRefGoogle Scholar
Daines, M.J. and Richter, F.M. (1988) An experimental method for directly determining the interconnectivity of melt in a partially molten system. Geophys. Res. Letts., 15, 1459-62.CrossRefGoogle Scholar
Fowler, A.C. (1985) The formation of freckles in binary alloys. IMA J. Appl Maths., 35, 159–74.CrossRefGoogle Scholar
Harte, B., Hunter, R.H. and Kinny, P.D. (1993) Melt geometry, movement and crystallization in relation to mantle dykes, veins and metasomatism. Phil. Trans. R. Soc., London. A342, 1—21.Google Scholar
Hunter, R.H. (1987) Textural equilibrium in layered igneous rocks. In Origins of igneous layering.(Parsons, I., ed.), pp 473—503.Google Scholar
Huppert, H.E. (1990) The fluid dynamics of solidification. J. Fluid Mech., 212, 209–40.CrossRefGoogle Scholar
Jurewitz, S.R. and Watson, B.E. (1985) The distribution of partial melt in a granite system: The application of liquid phase sintering theory. Geochim. Cosmochim. Acta, 49, 1109-21.CrossRefGoogle Scholar
Laporte, D. (1988) Wetting angle between silicic melts and biotite. Abstract. Trans. AGU, 69, No. 44, p. 1411.Google Scholar
Mahood, G.A. and Cornejo, P.C. (1992) Evidence for ascent of differentiated liquids in a silicic magma chamber found in a granitic pluton. Trans. Royal Soc. Edin., 83, 63–9.Google Scholar
Martin, D. (1990). Crystal settling and in situ crystallization in aqueous solutions and magma chambers. Earth Planet. Sci Lett., 96, 336–48.CrossRefGoogle Scholar
McCarthy, T.S. and Robb, L.J. (1978) On the relationships between cumulus mineralogy and trace and alkali element chemistry in an Archean granite from the Barberton region, South Africa. Geochim. Cosmochim. Acta, 42, 21–6.CrossRefGoogle Scholar
McKenzie, D.P. (1984) The generation and compaction of partially molten rock. J. Petrol., 25, 713–65.CrossRefGoogle Scholar
Petford, N. (1993) Porous media flow in granitoid magmas: an assessment. In Flow and Creep in the Solar System: Observations, Modelling and theory. (Stone, D.B. and Runcorn, S.K., eds.). Kluwer Academic Publishers, Netherlands, 261—86.Google Scholar
Ragland, P.C. and Butler, J.R. (1972) Crystallization of the West Farrington pluton, North Carolina, U.S.A. 7. Petrol, 13, 381–404.CrossRefGoogle Scholar
Sawka, W.N., Chappell, B.W. and Kistler, R.W. (1990) Granitoid compositional zoning by side-wall boundary layer differentiation: evidence from the Palisade Crest intrusive suite, Central Sierra Nevada, California. J. Petrol., 31, 519–53.CrossRefGoogle Scholar
Shaw, H.R. (1972) Viscosities of magmatic silicate liquids: an empirical method of prediction. Amer. J. Sci., 212, 870-89.Google Scholar
Smith, C.S. (1948) Grains, phases, and interfaces: an interpretation of microstructure. A.I.M.E. Trans., 175, 15-51.Google Scholar
Sparks, R.S., Huppert, H.E. and Turner, J.S. (1985) The fluid dynamics of evolving magma chambers. Phil. Trans. R. Soc., London A310, 511—34.Google Scholar
Tail, S. and Jaupart, C. (1992) Compositional convection in a reactive crystalline mush and melt differentiation. J. Geophys. Res., 97, 6735–56.Google Scholar
Tindle, A.G. and Pearce, J.A. (1981) Petrogenetic modelling of in situfractional crystallization in the zoned Loch Doon pluton, Scotland. Contrib. Mineral. Petrol., 78, 196–207.Google Scholar
Worster, M.G. (1991) Natural convection in a mushy layer. J. Fluid Mech., 224, 335–59.CrossRefGoogle Scholar