Ph.D. Dissertation Defense—August 10: Chad W. Carlson (Advisor Jim Faulds)

Ph.D. Dissertation DefenseAugust 10: Chad W. Carlson (Advisor Jim Faulds)

A Message from Marie Russell (Department of Geological Sciences and Engineering): “You are invited to attend PhD candidate Chad Carlson’s dissertation defense on Thursday, August 10, 2017.  The Defense will be held in DMS 105, at 2:00 PM.”

Kinematics and Transfer Mechanisms of Strain Accommodation at the Transition between the Northern and Central Walker Lane, Western Nevada
Dissertation Author: Chad Carlson

The Walker Lane is a relatively young and developing tectonic intraplate boundary, where ~20% of the dextral motion between the Pacific and North American plates is accommodated. Paralleling the more discrete, well-developed, and through-going San Andreas fault system to the west, the Walker Lane consists of discontinuous structural domains characterized by systems of dextral, sinistral, and normal faults. The manner in which some these disparate fault systems accommodate and transfer dextral strain remain enigmatic and are relatively understudied. Also, it has been suggested that the Walker Lane will eventually mature and take over as the principal tectonic boundary between the Pacific and North American plates in the future. As such, the Walker Lane provides a natural laboratory to examine the early development of a major tectonic plate boundary.

At the transition between the central and northern Walker Lane, all three characteristic types of Walker Lane structural domains reside, share boundaries, and have been documented to accommodate regional dextral shear. In the central Walker Lane (Walker Lake structural domain), northwest-striking dextral faults accommodate northwest translation of crustal blocks. Northwest of these dextral faults, east-northeast-striking sinistral faults and oroclinal flexure in the southern part of the northern Walker Lane (Carson structural domain) accommodate clockwise, vertical-axis rotation of sinistral fault-bounded blocks. A region of northerly-striking normal faults and asymmetric basins resides west of the central Walker Lane and south of the northern Walker Lane, where geodetic studies define northwest-directed dextral strain devoid of major strike-slip fault systems. Combined, these regions act in concert to accommodate dextral shear at the latitudes of the central-northern Walker Lane transition. The purpose of this research was to elucidate the kinematics and transfer mechanisms of regional dextral shear accommodation among and between disparate styles of deformation. To accomplish this, geologic mapping of key regions and paleomagnetic study of Tertiary volcanic rocks were conducted.

New Geologic Map—Black Warrior Geothermal Area, Washoe and Churchill Counties

Preliminary Geologic Map of the Truckee Range, Black Warrior Geothermal Area, Washoe and Churchill Counties, Nevada
Authors: Andrew J. Sadowski and James E. Faulds
Year: 2016
Series: Open-File Report 2016-07
Version: first edition, July 2017
Format: map: 40 x 30 inches, color, cross sections; text: 12 pages, color
Scale: 1:24,000

The Black Warrior geothermal system lies 20 km east of the southern end of Pyramid Lake in the Truckee Range of northwestern Nevada. It is an amagmatic blind geothermal system, lacking hydrothermal surface manifestations (no fumaroles, hot springs, sinter deposits, or high temperature alteration) and also lacks recent (<5 Ma) volcanism. The system was discovered through temperature gradient drilling (100–600 m depth) by Phillips Petroleum Company in the 1980s (Sass et al., 1999). The Black Warrior area, synonymous with the North Valley prospect, exhibits a maximum observed temperature of ~128°C at 552 m surrounded by elevated temperature gradients (figure 2). Also, a weak shallow anomaly was observed with a 2-m temperature survey circa 2009 (Kratt, personal communication).

The 1:24,000-scale geologic map of the Black Warrior geothermal area showcases the results of detailed stratigraphic and structural analyses. The map focuses on the Truckee Range in northwestern Nevada and covers portions of four adjoining 7.5-minute quadrangles: Black Warrior Peak, Russell Peak, Nixon, and Juniper Peak. The detailed map was produced to evaluate the structural controls of the Black Warrior geothermal system and overall geothermal potential of the area (Sadowski and Faulds, 2015; Sadowski, 2016).

Ultimately, the structural relationships at Black Warrior may help to guide exploration efforts for other blind geothermal systems in the Great Basin region and other extensional settings.

This map was prepared with support from the Great Basin Center for Geothermal Energy, the U.S. Department of Energy, Nevada Petroleum and Geothermal Society, American Association of Petroleum Geologists, and Geological Society of America.

New Report—Geology and Geophysics of White Pine and Lincoln Counties

Geology and Geophysics of White Pine and Lincoln Counties, Nevada, and Adjacent Parts of Nevada and Utah: The Geologic Framework of Regional Groundwater Flow Systems
Authors: Peter D. Rowley, Gary L. Dixon, Edward A. Mankinen, Keith T. Pari, Darcy K. McPhee, Edwin H. McKee, Andrew G. Burns, James M. Watrus, E. Bartlett Ekren, William G. Patrick, and Judith M. Brandt
Year: 2017
Series: Report 56
Format: text: 146 pages; 4 plates: color, with cross sections
Scale: 1:250,000

This report describes the geologic framework of a >65,000 km2 area that straddles the Nevada-Utah border. The studied region includes most of White Pine and Lincoln counties and adjacent counties in eastern Nevada, as well as parts of Tooele, Juab, Millard, Beaver, and Iron counties in western Utah. This study represents more than a 20-year effort by the Southern Nevada Water Authority (SNWA) to understand the groundwater resources of this part of the Great Basin. This first step, which includes a compilation of all the information on the geologic and geophysical setting, was necessary for hydrological and biological investigations. To understand the geologic framework, we compiled all known geologic mapping at a scale of 1:250,000, and constructed 25 geologic cross sections at the same scale. We also present new geophysical data, consisting of gravity surveys and audiomagnetotelluric (AMT) profiles, plus assembly of available aeromagnetic data, contracted from the U.S. Geological Survey (USGS), as well as additional AMT profiles by the SNWA. This report focuses on two large regional groundwater flow systems: the White River and Great Salt Lake Desert systems. Although the map boundaries presented here bound these aforementioned flow systems, the maps, cross sections, and text are intended to serve as a modern multidisciplinary regional geological and geophysical review, comparable to many old county reports in Nevada and Utah.

View the geospatial PDFs for the four plates that accompany this report:

Plate 1—Geologic map of the northern part of the study area, Nevada and Utah
Plate 2—Geologic map of the southern part of the study area, Nevada and Arizona
Plate 3—Geologic cross sections of the northern part of the study area, Nevada and Utah
Plate 4—Geologic cross sections of the southern part of the study area, Nevada and Arizona

GIS files for these plates will be available soon.

This report was prepared with support from the Southern Nevada Water Authority.

“This report is dedicated to Gary L. Dixon, who died at age 73 from cancer on January 14, 2017 as the manuscript was being reviewed and edited. Gary, a great field geologist, led the 20-year study presented here through the strength of his competence and personality. He began the study when he was a Geologist with the U.S. Geological Survey. After retirement, he continued with it as a consulting geologist. Perhaps more important to his coauthors and many others, we loved Gary and can attribute major parts of our careers to mentorship by him and to collaboration with him. To his wife, Wendy Dixon, and his children, Chris Dixon and Natalie Dixon Pique, he was a loving husband and father and a loyal friend to them and most others he met. His passions were geology, golf, and supporting Wendy’s equally extraordinary career with the U.S. Department of Energy. All of us miss him.” (Report 56)