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Compositional variation of muscovite in medium- to high-grade metapelites of northwestern Maine
| Content Provider | Semantic Scholar |
|---|---|
| Author | Gunoru, Chenr-Ns V. |
| Copyright Year | 1978 |
| Abstract | Detailed chemical analyses of muscovite from high-Al metapelites of lower garnet zone to upper sillimanite zone show a number of systematic changes with metamorphic grade. However, the pattern of changes for several elements in muscovite from the lower garnet zone to upper staurolite zone is markedly different from that for the upper staurolite zone to upper sillimanite zone. Although Si decreases and Ti increases across the whole metamorphic spectrum, in the upper staurolite zone Alvr, )Al, and Na/(Na * K) attain maxima and Fe, Mg, and )(Mg + Fe) attain minima. In the garnet and staurolite zone rocks, the systematic variations in the composition of the tetrahedral and octahedral sites of muscovite can be attributed to l-controlled continuous reactions which cause a decrease in the celadonite content ofmuscovite. A secondary control is a small expansion of the Ti saturation limit of muscovite. In the range from upper staurolite zone to upper sillimanite zone, the celadonite content of muscovite seems little affected by increase of T, primarily because the presence of sillimanite results in Al-saturated muscovite. However the Ti saturation limit in muscovite expands markedly over this metamorphic range, and the requirement of charge balance for the Tia+ cation appears to control the other tetrahedral and octahedral cation changes. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://rruff.info/doclib/am/vol63/AM63_878.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
