INTERIM GEOLOGICAL INVESTIGATIONS IN THE U12e.03a AND U12e.03b TUNNELS, NEVADA TEST SITE, NYE COUNTY, NEVADA
The UI2e.03a and U12e.03b tunnels are a part of the Ul2e tunnel system, whlch has been driven southwestward beneath Rainier Mesa ln the northern part of the Nevada Test Site. The tunnels were driven in nonwelded tuff of Tunnel Beds 4 and 3 near the top of the lower member of the Oak Spring Formation of Miocene or younger Tertiary age. At distances of 705 to 755 feet below the tunnels the hard resistant dolomite of Paleozoic age underlies the tuffs of the Oak Spring Formation. The vertical distance to the surface of Rainier Mesa is 1,318 feet above the end of the U12e.03a tunnel and 1,360 feet above the end of the U12e.03b tunnel. The tuffs in the Ul2e.03a tunnel strike N. 89 deg E. and dip 3 deg S.; they strike N. 86 deg W, and dip 9 deg S. in the U12e.03b tunnel. The relati ely simple structure in the U12e.03a tunnel is modified slightly by three normal faults of small displacement; the structure of the U12e.03b tunnel is uncomplicated by faults or folds. Joints are common ln both tunnels with about 70 percent of them northwest trending and the remainder northeast trending. Dips of the joints are vertical or dip steeply to either the southeast, northeast, or southwest. The tuffs exposed in the U12e.03a and Ul2e.03b tunnels are similar chemically and physically to the tuffs studied elsewhere in the U12e tunnel. Results of a gammaradioactivity survey indicate that this type of survey cannot be used to aid stratigraphic discrimination. It does indicate that the radioactivity of the tuffs is low enough not to interfere with studies of gamma- emitting radioisotope distribution resulting from underground explosions of nuclear devices. Zones of anomalous radioactivity appear to be related to fracturing or faulting. (auth)
- Research Organization:
- Geological Survey, Washington, D.C.
- NSA Number:
- NSA-16-011936
- OSTI ID:
- 4790676
- Report Number(s):
- TEI-806
- Country of Publication:
- United States
- Language:
- English
Similar Records
INTERIM GEOLOGICAL INVESTIGATIONS IN THE U12b.08 TUNNEL, NEVADA TEST SITE, NYE COUNTY, NEVADA
U. S. Geological Survey investigations in connection with the dining car event, U12e. 18 tunnel, rainier mesa, Nevada test site