Abstract
Although regional mineral zoning in pelitic rocks has been described in numerous metamorphic terrains, relatively little is known about zoning in carbonate-bearing rocks. Regional metamorphism has resulted in a distinctive sequence of mineral zones in calcareous rocks (containing Fe, K and Al) of the Lessard Formation in the Bishop Corners-Madoc area, Grenville Province, Canada. The variation in metamorphic grade represented by the mineral zoning is attributed to a gradient in physical conditions (mainly temperature) at the time of metamorphism.
In areas where pelitic schist and siliceous dolomite marble are rare or restricted in distribution, the mineral zones and isograds in impure calcareous rocks provide an alternative to conventional isograds for evaluating variations in metamorphic grade. In a metamorphic terrain where all three rock types occur, comparison of these isograds to those in pelitic and siliceous dolomite rocks results in a more accurate assessment of the distribution of isotherms and may provide some insight into the properties of the metamorphic fluid phase.
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References
Carmichael, D. M.: Structure and metamorphism in the Whetstone Lake area, Ontario: Unpubl. PhD Thesis, University of California (Berkley) 1966
Carmichael, D. M.: Intersecting isograds in the Whetstone Lake area, Ontario. J. Petrol. 11, 147–181 (1970)
Deer W. A., Howie, R. A., Zussman, J.: An introduction to rock forming minerals. London: Longmans 1966
Gordon, T. M., Greenwood, H. J.: The stability of grossularite in H2O-CO2 mixtures. Am. Mineralogist 56, 1674–1688 (1971)
Greenwood, H. J.: The N-dimensional tie-line problem. Geochim. Cosmochim. Acta 31, 465–490 (1967)
Hounslow, A. W., Moore, J. M., Jr.: Chemical petrology of Grenville schists near Fernleigh, Ontario. J. Petrol. 8, 1–28 (1967)
Kennedy, W. Q.: Zones of progressive regional metamorphism in the Moine Schists of the Western Highlands of Scotland. Geol. Mag. 86, 43–56 (1949)
Kretz, R.: Chemical study of garnet, hornblende, and biotite from gneisses of southwest Quebec, with emphasis on distribution of elements in coexisting minerals. J. Geol. 67, 371–402 (1959)
Moore, J. M., Jr.: Grenville structure, stratigraphy and metamorphism, southeastern Ontario: Northbrook-Ompah area. In: Jenness, S. E. (ed.), Guidebook — Geology of parts of eastern Ontario and western Quebec, Queens University, Kingston 1967
Moore, J. M., Thompson, P. H.: The Flinton Group, Grenville Province, eastern Ontario. Proc. XXIV Int. Geol. Cong. Sect. 1, 221–229 (1972)
Rucklidge, J., Gasparrini, E. L.: Specifications of a computer program for processing electron microprobe analytical data. EMPADR VII Dept. Geology, University of Toronto 1969
Sethuraman, K.: Petrology of Grenville metavolcanic rocks in the Bishop Corners-Donaldson area, Ontario. Unpubl. PhD thesis, Carleton University 1970
Sethuraman, K., Moore, J. M., Jr.: Petrology of metavolcanic rocks in the Bishop CornersDonaldson area, Grenville Province, Ontario. Can. J. Earth Sci. 10, 589–614 (1973)
Skippen, G. B.: Experimental data for reactions in siliceous marbles. J. Geol. 79, 457–481 (1971)
Thompson, P. H.: Stratigraphy, structure and metamorphism of the Flinton Group in the Bishop Corners-Madoc area, Grenville Province, eastern Ontario. Unpubl. PhD. thesis, Carleton University, 1972
Tilley, C. E.: The facies classification of metamorphic rocks. Geol. Mag. 61, 167–171 (1924)
Trommsdorff, V.: Progressive Metamorphose kieseliger Karbonategesteine in den Zentralalpen, Schweiz. Schweiz. Mineral. Petrog. Mitt. 46, 431–460 (1966)
Trommsdorff, V.: Change in T-X during metamorphism of siliceous dolomitic rocks of the central Alps. Schweiz. Mineral. Petrog. Mitt. 52, 567–570 (1973)
Wenk, E.: Plagioklas als indexmineral in den Zentralalpen. Schweiz. Mineral. Petrog. Mitt. 42, 139–152 (1962)
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Thompson, P.H. Mineral zones and isograds in “impure” calcareous rocks, an alternative means of evaluating metamorphic grade. Contr. Mineral. and Petrol. 42, 63–80 (1973). https://doi.org/10.1007/BF00521648
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DOI: https://doi.org/10.1007/BF00521648