Geology of the Adirondack Mountains (cont.)
Adirondack Highlands: AMCG Suite (cont.)
Figure 4-13. Deformed anorthositic-gabbroic gneiss.
Outcrop southwest of Elizabethtown. Deformation is Ottawan (McLelland, 1992). Anorthositic gabbro in most of the photo, except for the anorthositic bottom-right corner. Notice the large garnet megacryst which truncates the foliation. Quarter for scale.
Figure 4-14. Keene gneiss at Hulls Falls, East Branch of Ausable River, south of Keene.
Keene gneiss was so named by Miller (1918). It results from the mixing of anorthosite (whiter), charnockite and mangerite, both darker and containing blue andesine xenocrysts. Keene gneiss belongs to the AMCG suite, as confirmed by Hamilton (2004)'s dating. Nickel for scale.
Figure 4-15. Gabbro and anorthositic gabbro, west of Pumpkin Hollow.
Deformed gabbro (darker) and anorthositic gabbro (lighter). Penny for scale.
Figure 4-16. Mangerite south of Tupper Lake.
Outcrop on the eastern side of Tupper Lake, on the western margin of Marcy massif.
Figure 4-17. Mangerite close-up.
Mangerite at Tupper Lake contains blue andesine xenoliths, like the one at the center (several cm wide). White crystals are mostly mesoperthite and black minerals pyroxene.