Reconnaissance seismic refraction studies at Calico Hills, Wahmonie, and Yucca Mountain: southwest Nevada Test Site, Nye County, Nevada

Technical Report · Fri Dec 31 04:00:00 EST 1982

OSTI ID:59640

Pankratz, L W

Reconnaissance refraction surveys consisting of a total 5 spreads were conducted in the Calico Hills, Wahmonie, and Yucca Mountain areas, southwestern Nevada Test Site (NTS). Data from Calico Hills and Wahmonie are generally high in quality; data from Yucca Mountain are for the most part low in quality. At Calico Hills and Wahmonie, special attention was focused on the possible occurrence of a major intrusive body at depth. At Calico Hills this occurrence is supported by an inferred dome-shaped velocity interface, possibly associated with the roof of an altered phase of argillite. however, if an intrusive body is present, its top must be buried deeper than 3 km or it must be so pervasively altered that its velocity is similar to that of the calcareous argillite encountered at the bottom of drill hole UE 25a-3. At Wahmonie, the seismic data suggest the occurrence of a massive lenticular unit within 60 m of the ground surface, probably consisting of argillite but possibly consisting of intensively altered intrusive rock. At Yucca Mountain, preliminary interpretations of the most reliable data suggest the occurrence of a major, steeply inclined velocity interface 500 m from the southwest end of the Yucca C spread. This interface may represent a major fault or erosional feature separating the Topopah Spring and Tiva Canyon Members with Paintbrush Tuff at depth. This interface is 800 m east of a previously mapped fault. On the basis of poor-quality data obtained at Yucca Mountain, the subsurface velocity distribution appears to be complex. For example, one spread near drill hole UE25 a-1 suggests not only a much thicker section of Tiva but also that this material is down thrown in the valley. This may suggest faulting with throws exceeding 100 meters or an equivalent erosional feature.

• Research Organization: Geological Survey, Denver, CO (United States)
• DOE Contract Number: AI08-78ET44802
• OSTI ID: 59640
• Report Number(s): USGS-OFR--82-478; ON: DE83005619
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
58 GEOSCIENCES
GEOLOGIC DEPOSITS
GRANITES
NEVADA
NEVADA TEST SITE
RADIOACTIVE WASTE DISPOSAL
SEISMIC SURVEYS
SITE SELECTION
TUFF
Yucca Mountain Project