Compositional controls on spinel clouding and garnet formation in plagioclase of olivine metagabbros, Adirondack Mountains, New York

McLelland, J. M.; Whitney, P. R.

Abstract:

Olivine metagabbros from the Adirondacks usually contain both clear and spinel-clouded plagioclase, as well as garnet. The latter occurs primarily as the outer rim of coronas surrounding olivine and pyroxene, and less commonly as lamellae or isolated grains within plagioclase. The formation of garnet and metamorphic spinel is dependent upon the anorthite content of the plagioclase. Plagioclase more sodic than An38??2 does not exhibit spinel clouding, and garnet rarely occurs in contact with plagioclase more albitic than An36??4. As a result of these compositional controls, the distribution of spinel and garnet mimics and visually enhances original igneous zoning in plagioclase. Most features of the arrangement of clear (unclouded) plagioclase, including the shells or moats of clear plagioclase which frequently occur inside the garnet rims of coronas, can be explained on the basis of igneous zoning. The form and distribution of the clear zones may also be affected by the metamorphic reactions which have produced the coronas, and by redistribution of plagioclase in response to local volume changes during metamorphism. ?? 1980 Springer-Verlag.

Genre:

Article

ProdID:

70012609

Citation Author:

McLelland, J. M.; Whitney, P. R.

Citation Contributing Office:

Citation Datum:

Citation Day:

Citation Edition:

Citation Editor:

Citation End Page:

251

Citation Issue:

Citation Keywords:

Citation Language:

English

Citation Larger Work Title:

Contributions to Mineralogy and Petrology

Citation LatN:

Citation LatS:

Citation LonE:

Citation LonW:

Citation Month:

Citation No Pagination:

Citation Number Of Pages:

Citation Online Only Flag:

Citation Phsyical Description:

Citation Projection:

Citation Public Comments:

Citation Publisher:

Citation Series:

Citation Series Code:

Citation Series Number:

Citation Search Results Text:

Compositional controls on spinel clouding and garnet formation in plagioclase of olivine metagabbros, Adirondack Mountains, New York; 1980; Article; Journal; Contributions to Mineralogy and Petrology; McLelland, J. M.; Whitney, P. R.