Anorthosite

Title

Anorthosite

Identifier

AD-17

Description

The specimen was collected from the Oregon Dome Massif. The Oregon Dome is similar in all respects to the anorthosites described and analyzed by Buddington (1939) for the Adirondack High Peaks region (Marcy Massif). Texturally, the present specimens are partly granulated and are fairly typical of Adirondack anorthosites situated near the margins of the massifs. Of particular interest in this specimen is the occurrence of garnet. In general, this rims both oxides, usually ilmenite and clinopyroxene (and sometimes cored by orthopyroxene). The assemblage is typical of garnet-clinopyroxene subfacies of the granulite (deWaard, 1965).

The following information is from the original OCR document: The reactions producing this assemblage have been discussed by McLelland and Whitney, "Origin of Garnet in the Anorthosite-Charnockite Suite of the Adirondacks" 1977, Contributions to Mineralogy and Petrology, v. 60, p.161-181.
Thin section shows plagioclase and orthopyroxene.

Date

1980

Contributor

Western Minerals Inc.

Spatial Coverage

Adirondack Highlands-collected from a road cut on NY Route 30, 1/2 mile south of junction old route 30 and about 2 miles north of junction NY Route 8.

Temporal Coverage

Precambrian

Accrual Method

Purchased from Western Minerals Inc.

Unit

Oregon Dome Massif

Number of Thin Sections

1

Geolocation