Geology of the Gold Meadows stock, Nevada Test Site

The Gold Meadows stock crops out in an elongate pattern about 1 mile (1.6 km) north of Rainier Mesa in the Nevada Test Site, Nevada. The long axis trends N. 350E. Core and cuttings from three drill holes in the stock were analyzed chemically and petrographically. Modally the rock ranges from granodiorite to calc-alkaline granite, and three of five modes indicate that the rock is quartz monzonite. Chemically the rock differs from Nockolds' average quartz monzonite thusly: more SiO2; slightly less than half total Fe; one-fourth MgO, same Na2O and K2O; Al2O3, CaO, and TiO range downward from slightly less than Nockolds' average to about one-half. The age of the stock has been determined by K/Ar dating to be 91.8 +- 2.6 m.y. Gravity data indicate the stock rose from southwest of the present outcrop. Flowbanding also indicates a source area to the southwest. Groundwater measurements from one deep drill hole indicate perched water at several places in the stock