Tishomingo and Troy Granites

ARDMORE-SHERMAN- Granite, pink, with much microcline and biotite; "Troy" is fine grained; "Tishomingo" is coarse grained. Estimated thickness, 10 miles. (1.3 billion years old) Occurs in the ARBUCKLE MTNS.
State Oklahoma
Name Tishomingo and Troy Granites
Geologic age Middle Proterozoic
Lithologic constituents
Igneous > Plutonic > Granitic > Granite (Batholith)
Comments TISHOMINGO:Named for Tishomingo, capital of Chickasaw Nation, Indian Territory, Midcontinent region, Johnston Co, OK. No type locality designated. Occurs in Tishomingo quad Is a coarse-grained, pink or reddish, microcline-rich granite with numerous basic dikes. Biotite is always present. Accessory minerals are zircon, apatite, magnetite, and sometimes garnet. Quartz monzonite occurs in intimate association with the granite and appears as phases of it. (Taff, 1902). TROY: Probably named for town of Troy, Johnston Co, OK, in Arbuckle Mountains district. Present on the southeastern flank of the exposed portion of the Arbuckle uplift, in Johnston Co (S. Oklahoma folded belt province) and Atoka Co (Ouachita tectonic belt province). Probably part of same intrusive body as Tishomingo granite, which is also present in this area. When unaltered, Troy is a medium- to fine-grained gray granite, speckled with black. It shows cleavage surfaces of a gray feldspar usually less than .5 mm broad, with occasionally a pinkish individual more than 1 cm across, rounded grains of colorless quartz, and many small black specks of biotite evenly distributed. There are 2 or 3 nearly vertical joint systems, spaced 2-40 ft apart, usually at right angles to each other. There are also strong sheet joints parallel or nearly parallel to the slopes of the granite hills, usually spaced 10-25 ft apart. (Taylor,1915).
NGMDB product
Counties Atoka - Johnston