Evidence for cyclic reactions between andalusite, "sericite" and sillimanite, mount franks area, willyama complex N.S.W

R. A. Glen*

*Corresponding author for this work

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

In the Mt. Franks area of the Willyama Complex, microfabric evidence suggests that the alteration of andalusite to sillimanite has taken place by a process similar to that suggested by Carmichael (1969). Andalusite is pre- to syn-S2 in age. Alteration to "sericite" has resulted in the formation of "sericite" laths, some of which are crenulated about S2, and some which are syn- and post-S2. "Fibrolite" occurs in these andalusite-"sericite" aggregates within the sillimanite zone and is wholly embedded in "sericite". "Fibrolite" is pre- to syn-S2 in age. This evidence is interpreted as suggesting that the formation of sillimanite from andalusite took place via a "sericite" phase. Further microfabric observations are interpreted to imply constant volume for the reaction aluminosilicate → "sericite". This suggests a situation in which Al3+ is relatively mobile but Al4+ is relatively immobile. This suggestion differs from Carmichael's (1969) idea of Al3+ immobility.

Original languageEnglish
Pages (from-to)97-112
Number of pages16
JournalTectonophysics
Volume58
Issue number1-2
DOIs
Publication statusPublished - 10 Sep 1979
Externally publishedYes

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