|Name||Tishomingo and Troy Granites|
|Geologic age||Middle Proterozoic|
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).|
Heran, W.D., Green, G. and Stoeser, D.B., 2003, A Digital Geologic Map Database of Oklahoma: USGS Open File Report 03-247, scale 1:250,000.
Hart, D.L., 1974, Reconnaissance of the water resources of the Ardmore and Sherman quadrangles, southern Oklahoma: Oklahoma Geological Survey, Hydrologic Atlas 3, scale 1:250,000, 4 sheets. (Geology on sheet 1 compiled by D.L. Hart, and R.O. Fay, in 1970.)
Cederstrand, J.R., 1996a, Digital geologic map of Ardmore-Sherman quadrangles, south-central Oklahoma: U.S. Geological Survey Open-File Report 96-370, (3 diskettes), URL address is: http://ok.water.usgs.gov/gis/geology
Taff, J.A., 1902, Description of the Atoka quadrangle [Indian Territory]: U.S. Geological Survey Geologic Atlas of the United States, Folio 79.
Taylor, C.H., 1915, Granites of Oklahoma: Oklahoma Geological Survey Bulletin 20.
|Counties||Atoka - Johnston|