Hostname: page-component-848d4c4894-nmvwc Total loading time: 0 Render date: 2024-06-15T02:35:42.814Z Has data issue: false hasContentIssue false
  • English
  • Français

The origin and petrogenetic significance of hour-glass zoning in titaniferous clinopyroxenes

Published online by Cambridge University Press:  05 July 2018

Suzanne Y. Wass
Suzanne Y. Wass*
Affiliation:
School of Earth Sciences, Macquarie University, North Ryde, N.S.W., 2113, Australia
Get access Rights & Permissions [Opens in a new window]

Summary

Tertiary alkali basaltic rocks from the Southern Highlands, New South Wales, contain two types of clinopyroxene crystals, which exhibit excellent morphological development of hour-glass zoning. These are small, quench clinopyroxene crystals and large, abundant, euhedral phenocrysts. Electron microprobe analyses show that the different zone sectors derive from compositional differences, with variation in TiO2 and Al2O3 contents inversely with SiO2 content being most significant. Increased depth of colour of titanaugites depends on increased coupled substitution of Al for Si in tetrahedral sites and of Ti3− in an M1 site, while pleochroism is enhanced by increasing Fe content. It is suggested that the formation of hour-glass zoning is determined by an environment of crystallization where initial crystal growth is rapid relative to ionic diffusion in the melt, resulting in different chemistry for different growth directions within the crystal. This implies that, under certain conditions, kinetic factors, as well as the chemical composition of the host magma, may be significant in determining the chemical composition of phases precipitated, particularly where more than one crystallographic direction of growth is possible.

Type
Research Article
Information
Mineralogical Magazine , Volume 39 , Issue 302 , June 1973 , pp. 133 - 144
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1973

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

Bence, (A. E.) and Papike, (J. J.), 1971. Earth Planet. Sci. Lett. 10, 245-51.CrossRefGoogle Scholar
Boyd, (F. R.) and Smith, (D.), 1971. Journ. Petrology, 12, 439-64.CrossRefGoogle Scholar
Burns, (R. G.), 1966. Min. Mag. 35, 715-19 [M.A. 17613].Google Scholar
Burns, (R. G.) 1970. Mineralogical applications of crystal field theory. Cambridge (C.U.P.) [M.A. 2O-1073].Google Scholar
Burns, (R. G.), Clarke, (R. H.), and Fyfe, (W. S.), 1964. In Chemistry of the earth's crust. Proc. Vernadsky Centen. Symp. 2, 88-106. Vinogradov, (A. P.) ed. (Transi. Israel Progr. Sci. Transi., Jerusalem, 1967, 93 112).Google Scholar
Burns, (R. G.), Clarke, (R. H.), and Fyfe, (W. S.) and Fyfe, (W. S.), 1967. In Researches in Geochemistry, Abelson, (P. H.) ed., 2, 259-85, New York (Wiley) [M.A. 19-87],Google Scholar
Farquhar, (O. C.), i960. Kept. 21st. Sess. Int. Geol. Congr., Norden, 21, pt 21, 194-200 [M.A. 15100].Google Scholar
Hartman, (H.) and Schlafer, (H. L.), 1951. Zeits. phys. Chem. 197, 116-42.Google Scholar
Hollister, (L. S.), 1970. Amer. Min. 55, 742-66 [M.A. 2I-3348].Google Scholar
Hollister, (L. S.) and Hargraves, (R. B.), 1970. Geochimica Acta, Proc. Apollo II Lunar Science Conf. 1, 541-50 [M.A. 22-2108].Google Scholar
Manning, (P. G.), 1967. Canad. Min. 9, 237-51 [M.A. 20-2643].Google Scholar
Manning, (P. G.) and Nickel, (E. H.), 1969. Ibid. 10, 71 83 [M.A. 22-484].Google Scholar
Orgel, (L. E.), 1966. An Introduction to transition metal chemistry: ligandfield theory. London (Methuen).Google Scholar
Preston, (J.), 1966. Amer. Min. 51, 1227-33 [M.A. 19-47].Google Scholar
Rosenbusch, (H.), 1905. Mikroskopische Physiographic I pt. 2. Stuttgart. (Verlagshandlung.)Google Scholar
Smith, (A. L.) and Carmichael, (I. S. E.), 1969. Amer. Min. 54, 909-23 [M.A. 21846].Google Scholar
Strong, (D. F.), 1969. Min. Mag. 31, 472-9 [M.A. 2I-598].CrossRefGoogle Scholar
Vance, (J. A.), 1962. Amer. Journ. Sci. 260, 746-60 [M.A. I6-189].CrossRefGoogle Scholar
Wilkinson, (J. F. G.), 1957. Geol. Mag. 94, 123-34. [M.A. I4-206].CrossRefGoogle Scholar
Yagi, (K.) and Onuma, (K.), 1967. Journ. Fac. Sci. Hokkaido Univ. Ser. 4, 13, 463-83.Google Scholar
Zussman, (J.), 1968. Earth Sci. Rev. 4, 39 67.CrossRefGoogle Scholar