Williams, Lindsay Ann
(2011)
BRITTLE TERTIARY DETACHMENTS IN THE SPECTER RANGE, SOUTHERN NEVADA, AND THEIR IMPLICATIONS FOR GROUNDWATER FLOW SOUTHWARD FROM THE NEVADA TEST SITE.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
The Specter Range thrust (SRT), which extends from Mercury to Amargosa, Nevada, emplaces Precambrian silicic rocks of the Wood Canyon Formation onto middle Paleozoic folded rocks which constitute the regional carbonate aquifer. Field evidence suggests that the regional carbonate aquifer and underlying aquitard in the Specter Range have been thinned by nearly 35%, or 3,000 m along detachment horizons parallel or sub-parallel to bedding. Several regional detachments that generally coincide with sections of shaly or sandy beds also commonly affect hundreds of meters of adjacent beds as shown by breccia composed of granules to small boulders, as well as local large boulders and mega blocks, especially in dolomite units. Quartzose clastic confining units generally are strongly brecciated and may be unexpectedly porous and permeable. The stratigraphically highest breccia mass is preserved only in the southern Specter Range, where it comprises tens to hundreds of meters of breccias derived mainly of Silurian and Devonian dolomite beds. In these units, brecciated throughout, the formation of breccia is highly variable with the smallest grain size commonly developed along steep, narrow zones within coarser, massive breccia composed of mega-blocks and bedded sections cut and disrupted by numerous fractures and faults generally marked by breccias.The detachments and related contractional structures locally affect Tertiary strata that constrain the timing of deformation between about 15 and 10 Ma. As previously recognized, transpression at a left-step along the right-lateral Las Vegas Valley Shear Zone (LVVSZ), between Mercury and Amargosa, Nevada is likely responsible for the contraction. Stratigraphic studies have shown that the LVVSZ accommodates several tens of km of movement.The brecciated carbonate aquifer and clastic aquitard may provide fast pathways for groundwater moving from the NTS southward. Monitor wells in the vicinity of Rock Valley fault, north of the Specter Range, could provide information about southward-moving-groundwater before reaching the faulted and brecciated rocks of the Specter Range.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
14 September 2011 |
| Date Type: |
Completion |
| Defense Date: |
25 July 2011 |
| Approval Date: |
14 September 2011 |
| Submission Date: |
19 August 2011 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Geology and Planetary Science |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Detachments; Groundwater; Nevada Test Site; Specter Range |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-08192011-094747/, etd-08192011-094747 |
| Date Deposited: |
10 Nov 2011 20:00 |
| Last Modified: |
15 Nov 2016 13:49 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/9206 |
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