Rotation of late Cenozoic extensional stresses, Yucca Flat region, Nevada Test Site, Nevada
The Nevada Test Site (NTS) is located in the southern Basin and Range where the geology is typified by complexly deformed Paleozoic sedimentary rocks underlying Tertiary and Quaternary volcanics and alluvium all displaced by Cenozoic normal faults. The purpose of this study is to interpret the history of change in Cenozoic extensional stress orientations using ash-flow distributions, surface fault configurations, and slickenside analyses. Extensive drill hole data collected from Yucca Flat within NTS were used to construct isopach and structure contour maps of Cenozoic units occupying the northerly-trending basin. The configuration of these units indicates that the north-south-trending faults controlling present day basin morphology were inactive during deposition of the volcanic rocks from approximately 25 to 11 myBP. However, after 11 myBP, the overlying sedimentary sequence was strongly influenced by these faults and consequent basin development. In particular, an inordinately thick section of late Tertiary and Quaternary alluvium occurs at the southwestern end of Yucca Flat. Southwest-striking faults at the southwestern and of Yucca flat are postulated to be deflected at their northeast ends, becoming continuous with the north-south basin forming fault sets.
- OSTI ID:
- 60560
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1984
- Country of Publication:
- United States
- Language:
- English
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