Post-Silent Canyon caldera structural setting for Pahute Mesa
At Pahute Mesa, Nevada Test Site, the Silent Canyon caldera of about 14 Ma age is almost completely concealed beneath ash-flow tuffs of the 11.5 Ma old Rainier Mesa Member of the Timber Mountain Tuff. Structures unequivocally related to the caldera are not observed in the Rainier Mesa Member. Structure contours on top of Rainier Mesa Member at Pahute Mesa define a series of elongate, fault-bounded blocks. Between the East Boxcar and Almendro Faults these blocks tilt eastward away from westward-dipping normal faults and elsewhere they also have a strong northward component of dip, away from Timber Mountain caldera. Episodic movement along these faults controlled thicknesses of members of Paintbrush Tuff (13.3 - 12.7 Ma) and tuffs and lavas of Area 20 (14 - 13.3 Ma), which have steeper eastward and northward components of dip than the overlying Rainier Mesa Member and also thicken eastward within each structural block. Fault blocks north of Timber Mountain caldera on Pahute Mesa are very similar to blocks described at Yucca mountain south of the caldera, and probably were generated by regional Basin and Range extension and four episodes of caldera-forming volcanism at Timber Mountain. Faults bounding these blocks on Pahute Mesa formed during early episodes of caldera-forming volcanism at Timber Mountain and reactivated during later episodes, so that fault displacements and bedding plane attitudes increase with age. Because these faults have episodic activity, even a relatively small post-Rainier Mesa displacement may define the location of important displacement within underlying units.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- OSTI ID:
- 60620
- Report Number(s):
- CONF-850953-Vol.2; ON: DE86008380
- Resource Relation:
- Conference: 3. symposium on containment of underground nuclear explosions, Idaho Falls, ID (United States), 10-12 Sep 1985; Other Information: PBD: 1985; Related Information: Is Part Of Third symposium on containment of underground nuclear explosions. Volume 2. Proceedings; Olsen, C.W.; Donohue, M.L. (eds.); PB: 3-30 p.
- Country of Publication:
- United States
- Language:
- English
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