Hostname: page-component-78c5997874-94fs2 Total loading time: 0 Render date: 2024-11-02T19:57:57.822Z Has data issue: false hasContentIssue false
  • English
  • Français

Saddle dolomite: a new view of its nature and origin

Published online by Cambridge University Press:  05 July 2018

Alison Searl
Alison Searl*
Affiliation:
School of Earth Sciences, University of Birmingham, P.O. Box 363, Birmingham, B 15 2TT
Get access Rights & Permissions [Opens in a new window]

Abstract

Saddle dolomite is a common product of late-stage diagenesis and hydrothermal activity. It has been suggested that during growth Ca enrichment occurs towards crystal edges leading to a lattice expansion relative to face centres. However, backscatter scanning electron microscopy of eight samples has revealed that, instead of edge associated Ca enrichment, saddle dolomites have a series of edge associated Mg enriched wedges, between 5 and 20 µm thick and 300 µm long. Wedge geometry implies development of extra lattice layers at edges relative to face centres. It is suggested that the wedges develop during rapid, transport-controlled, crystal growth. The wedges possibly reflect a switching from continuous growth across the face to edge-nucleated growth as the boundary layer solution becomes progressively depleted. Continuous growth might be reinstigated through convective turnover of the boundary layer presenting fresh solution to the growing crystal.

Keywords

saddle dolomiteoscillatory zoningcrystal growth mechanismsBSEM imaging
Type
Non-silicate Mineralogy
Information
Mineralogical Magazine , Volume 53 , Issue 373 , December 1989 , pp. 547 - 555
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1989

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

Atkins, P. W. (1986) Physical Chemistry (3rd Edn).Google Scholar
Allegre, C. J., Provost, A. and Jaupart, C. (1981) Nature 294, 223-8.CrossRefGoogle Scholar
Barber, D. J. and Riaz Khan, M. (1987) Mineral. Mag. 51, 71-86.CrossRefGoogle Scholar
Barber, D. J. and Wenk, H. R. (1984) Contrib. Mineral. Petrol. 88, 233-45.CrossRefGoogle Scholar
Barber, D. J., Reeder, R. J. and Smith, D. J. (1985) Ibid. 91, 82-92.Google Scholar
Berner, R. A. (1983) In Kinetics of Geochemical Processes (Lasaga, A. C. and Kirkpatrick, R. J., eds.). Reviews in Mineralogy, Min. Soc. Am., 8, 111-34.Google Scholar
Boles, J. R. (1987) In Diagenesis of sedimentary sequences (Marshal, J. D., ed.). Spec. Publ. Geol. Lond. 36, 191–200.Google Scholar
Butler, G. P., Harris, P. M. and Kendal, G. C. St. C. (1982) In Deposition and diagenetic spectra of evaporites (Handford, C. R., Loucks, R. G. and Davies, G. R., eds.). Soc. Econ. Paleont. Mineral. Core Workshop 3, 33–64.CrossRefGoogle Scholar
Deer, W. A., Howie, R. A. and Zussman, J. (1966) An introduction to the rock-forming minerals. Longman.Google Scholar
Folk, R. L., Chafetz, H. S. and Tiezzi, P. A. (1985) In Carbonate Cements (Schneidermann, N. and Harris, P. M., eds.). Soc. Econ. Mineral. Paleont. Spec. Publ. 36, 349-70.CrossRefGoogle Scholar
Giles, M. R. (1987) Marine Petrol. Geol. 4, 183-204.CrossRefGoogle Scholar
Haase, C. S., Chadam, J., Feinn D. and Ortoleva, P. (1980) Science 209, 272-4.CrossRefGoogle Scholar
Hardie, L. A. (1987) J. Sed. Petrol. 57, 166-83.CrossRefGoogle Scholar
Hird, K., Tucker, M. E. and Waters, R. A. (1987) In European Dinantian Environments (Miller, J., Adams, A. E. and Wright, V. P., eds.), 359-78.Google Scholar
Krauskopf, K. B. (1979) Introduction to Geochemistry (2nd Edn).Google Scholar
Loomis, T. P. (1982) Contrib. Mineral. Petrol. 81, 219-29.CrossRefGoogle Scholar
Martin, D., Griffiths, R. W. and Campbell, I. H. (1987) Ibid. 96, 465-75.Google Scholar
Mattes, B. W. and Mountjoy, E. W. (1980) In Concepts and Models of Dolomitization (Zenger, D. H., Dunham, J. B. and Ethington, R. L., eds.). Soc. Econ. Mineral. Paleont. Spec. Publ. 28, 123-37.Google Scholar
Radke, B. M. and Mathis, R. L. (1980) J. Sed. Petrol. 50, 1149-68.Google Scholar
Sunagawa, I. (1977) J. Crystal Growth 42, 214-23.CrossRefGoogle Scholar
Sunagawa, I. (1981) Bull. Mineral. 104, 81-7.Google Scholar
Turner, J. S. (1979) Bouyancy effects in fluids. Cambridge Univ. Press, 368pp.Google Scholar
Weaver, C. E. (1973) Geology, 3, 425-9.2.0.CO;2>CrossRefGoogle Scholar