Zoned Garnets in Some Scottish Dalradian Pelites

C. Sivaprakash
Geological Department, The Associated Cement Cos., Ltd., 121 Maharshi Karve Road, Bombay 400 020, India

Abstract: Zoning in garnets in Barrovian garnet zone rocks of central Perthshire is shown to be dependent on the continuous prograde reaction histories in which the garnet was involved. In highly aluminous rocks, garnet grows at the expense of chloritoid and staurolite whereas in less aluminous rocks garnet grows at the expense of chlorite. Minerals included in garnet such as ilmenite, plagioclase, chlorite, and chloritoid show compositional changes which with the garnet zoning elucidate the garnet-forming reactions. Where garnet is resorbed to produce staurolite the former loses Fe at its rim to staurolite so that ‘reverse’ zoning of decreasing Fe and increasing Mn and Ca towards garnet rim develops.

Mineralogical Magazine; September 1981 v. 44; no. 335; p. 301-307; DOI: 10.1180/minmag.1981.044.335.10
© 1981, The Mineralogical Society
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