Abstract
Three important phases of deformation (D1-D3) affect the Precambrian metamorphic rocks of the Strathgordon region, S.W. Tasmania. Textural analysis has related phengite development to the deformation events in quartz + phengite phyllites. Phengite chemistry suggests a prograde metamorphic history at about 4 kb from 400°C at D1 to 450°C at D2. The significant feature of this work is that a sharp break in conditions, shown by a marked change in the composition of the phengites, occurs from D2 to D3, the latter taking place at about 250°C and at a pressure <4 kb. A pronounced hiatus in the deformation history is indicated for the D2/D3 interval. During D3 water was introduced.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Boulter, C.A.: Structural sequence in the metamorphosed Precambrian rocks of the Frankland and Wilmot Ranges, Southwestern Tasmania. Papers and Proc. Roy. Soc. Tasmania 107, 105–115 (1974)
Boulter, C.A.: Tectonic deformation of soft sedimentary clastic dykes from the Precambrian rocks of Tasmania, Australia. Bull. Geol. Soc. Am. 85, Sept. (1974) (in press)
Brown, E.H.: The Si4+ content of natural phengites: a discussion. Contr. Mineral. and Petrol. 17, 78–81 (1968)
Dewey, J.F., Pankhurst, R.J.: The evolution of the Scottish Caledonides in relation to their isotopic age pattern. Trans. Roy. Soc. Edinburg 68, (11), 351–387 (1970)
Etheridge, M.A.: Experimentally produced slaty and crenulation cleavages during a single deformation. J. Geol. Soc. Aust. 20, 223–227 (1973)
Etheridge, M.A., Hobbs, B.E.: Chemical and deformational controls on recrystallisation of mica. Contr. Mineral. and Petrol. 43, 111–124 (1974)
Fontijin, L.A., Bok, A.B., Kornet, J.G.: The TPD electron probe X-ray micro-analyzer. In: 5th Internat. Congress on X-ray Optics and Mica-Analysis (G. Mollenstedt and K.H. Gaukler, eds.), p. 261–268 (1969)
Gee, R.D., Marshall, B., Burns, K.L.: The metamorphic and structural sequence in the Precambrian of the Cradle Mountain area, Tasmania. Report of the Geol. Surv. Tas. No. 11 (1970)
Harte, B., Johnson, M.R.W.: Metamorphic history Dalradian rocks in Glens Clova, Esk and Lethnot, Angus, Scotland. Scott. J. Geol. 5, 54–80, 1969
Höck, V.: Coexisting phengite, paragonite and margarite in metasediments of the Mittlere Hohe Tauern, Austria. Contr. Mineral. and Petrol. 43, 261–274 (1974)
Johnson, M.R.W.: Relations of movement and metamorphism in Banffshire. Trans. Edinburgh Geol. Soc. 19, 29–64 (1962)
Means, W.D., Williams, P.F.: Crenulation cleavage and faulting in an artificial salt-mica schist. J. Geol. 80, 569–591 (1972)
Park, R.G.: Structural correlation in metamorphic belts. Tectonophysics 7, 323–338 (1969)
Råheim, A.: Petrology of the Strathgordon area, Western Tasmania: Si+4-content of phengite mica as monitor of metamorphic grade (1974a in prep.)
Råheim, A.: Mineral zoning as a record of P, T history of precambrian metamorphic rocks in Western Tasmania (1974b in prep.)
Råheim, A.: Petrology of eclogites and surrounding schists from the Lyell Highway-Collingwood River area (1974c in prep.)
Råheim, A., Compston, W.: Correlations between metamorphic events and Rb-Sr ages in metasediments and eclogites from Western Tasmania
Ramsay, J.G.: Folding and fracturing of rocks, p. 568 New York: McGraw Hill 1967
Rast, N.: Nucleation and growth of metamorphic minerals. In: Controls of metamorphism (Pitcher, W.S. and Flinn, G.W., eds.), p. 73–102. New York: Wiley 1965
Reed, S.J.B., Ware, N.G.: Quantitative electron microprobe analysis using a lithium-drifted silicon detector. Y-ray Spectrometry 2, 69–74 (1973)
Rickard, M.J.: A note on cleavages in crenulated rocks. Geol. Mag. 98, 324–332 (1961)
Rickard, M.J.: Taconic orogeny in the Western Appalachians Experimental application of microtextural studies to isotopic dating. Bull. Geol. Soc. Am. 76, 523–536 (1965)
Tobisch, O.T., Fleuty, M.J., Merh, S.S., Mukhopadhyay, D., Ramsay, J.G.: Deformational and metamorphic history of Moinian and Lewisian rocks between Strathconon and Glen Affric. Scott. J. Geol. 6, 243–265 (1970)
Velde, B.: Phengitic micas: Synthesis, stability and natural occurrence. Am. J. Sci. 263, 886–913 (1965)
Velde, B.: Si4+ content of natural phengites. Contr. Mineral. and Petrol. 14, 250–258 (1967)
Winkler, H.G.F.: Petrogenesis of metamorphic rocks. 237 pp. Berlin-Heidelberg-New York: Springer 1967
Zwart, H.J.: The chronological succession of folding and metamorphism in the central Pyrenees. Geol. Rundschau 50, 203–218 (1960)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Boulter, C.A., Råheim, A. Variation in si4+-content of phengites through a three stage deformation sequence. Contr. Mineral. and Petrol. 48, 57–71 (1974). https://doi.org/10.1007/BF00399110
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00399110