Proposed stratigraphic nomenclature and macroscopic identification of lithostratigraphic units of the Paintbrush Group exposed at Yucca Mountain, Nevada
This paper describes the formations of the Paintbrush Group exposed at Yucca Mountain, Nevada, presents a detailed stratigraphic nomenclature for the Tiva Canyon and Topopah spring Tuffs, and discusses the criteria that define lithostratigraphic units. The Tiva Canyon and Topopah Spring Tuffs are divided into zones, subzones, and intervals on the basis of macroscopic features observed in surface exposures and borehole samples. Primary divisions reflect depositional and compositional zoning that is expressed by variations in crystal content, phenocryst assemblage, pumice content and composition, and lithic content. Secondary divisions define welding and crystlalization zones, depositional features, or fracture characteristics. Both formations are divided into crystal-rich and crystal-poor members that have an identical sequency of zones, although subzone designations vary slightly between the two units. The identified lithostratigraphic divisions can be used to approximate thermal-mechanical and hydrogeologic boundaries in the field. Linking these three systems of nomenclature provides a framework within which to correlate these properties through regions of sparse data.
- Research Organization:
- USDOE Nevada Operations Office, Las Vegas, NV (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AI08-92NV10874
- OSTI ID:
- 366475
- Report Number(s):
- DOE/NV/10874--T4; USGS-OFR--94-469; ON: DE96014541
- Country of Publication:
- United States
- Language:
- English
Similar Records
Air-injection testing in vertical boreholes in welded and nonwelded Tuff, Yucca Mountain, Nevada
Petrographic and geochemical characteristics of a section through the Tiva Canyon Tuff at Antler Ridge, Yucca Mountain, Nevada