Archive | January 2018

AEG Great Basin Monthly Meeting – January 18th

Association of Environmental & Engineering Geologists, Great Basin Chapter, Monthly Meeting

SPEAKER: Jesse Ruzicka, P.E.
Principal Engineer, Nevada Department of Transportation
TOPIC: Soil Nails in the Lake Tahoe Basin: Lessons Learned

Mr. Ruzicka graduated from the University of Nevada, Reno in 2003 with an undergraduate degree in Geological Engineering. Since that time, he has been involved in numerous projects providing geotechnical design and support for residential developments, flood control projects in Sacramento and Reno, commercial/industrial developments, roadway and bridge design, and mining projects in Nevada, Canada, and Mexico. Most recently Mr. Ruzicka’s experience has been focused on the transportation industry, where he is currently the principal geotechnical engineer on several of NDOT’s recent projects including Phase II of the Boulder City Bypass, the I-15/US93 Garnet Interchange, SR28 Shared Use Path at Lake Tahoe, and the rockfall mitigation at Logan Shoals.

Mr. Ruzicka has been involved with AEG since 2001, serving as a past secretary of the Great Basin Section from 2010 to 2013 and chair from 2014 to 2016.

Soil nailing is one of the many tools available to the geotechnical professional when constructing vertical excavations and stabilizing existing slopes. Due to their economy, technical advantages, and relatively quick construction process, soil nails are commonly used in temporary excavations as well as permanent retaining applications. This presentation will summarize the concepts for designing soil nails in retaining wall and slope stability applications, construction, and load testing of soil nails, emphasizing the importance of involvement by the designer during construction.

Recent experiences from projects such as Logan Shoals and the SR28 Shared Use Path in Lake Tahoe have provided several lessons learned that will be shared during the presentation.

BY BEST WESTERN (Hotel name change – same location)
COST: Members: $27.00 ~ Non-Members: $30.00 ~ Students: $20.00

The Social Hour is sponsored by Madole Construction – Open Bar

Please give us a 48 Hour Cancellation notice if you are not able to attend.


Earthquake Swarm in South Reno

Nevada Seismological Lab reports swarm of 90 earthquakes in south Reno
University reports several magnitude 2 and lower quakes, no damage reported.
From Nevada Today, 1/12/2018, by Mike Wolterbeek

Read article here:

Earthquake information from NBMG:

January and February are Radon Awareness Months


Radon Awareness MonthsJan and Feb 2018Free Radon Test Kits!
Learn about radon hazards and how you can test your home or business for free:

“According to EPA estimates, exposure to radon is the leading cause of lung cancer among nonsmokers and is responsible for about 21,000 lung cancer deaths every year, more than drunk driving, household falls, drowning, or home fires.”

Can radon problems be fixed or prevented? Director of the University of Nevada Cooperative Extension’s Radon Education Program Susan Howe breaks down radon health risks, remediation and prevention.

From Nevada Today, 1/11/2018, by Susan Howe
Read article here:

EPA National Radon Action Month Information

New GIS Files are Now Available

GIS files are now available for the following NBMG publications. Please click on links below for details.

Surficial geology, hydrology, and late Quaternary tectonics of the IXL Canyon area, Nevada, as related to the 1954 Dixie Valley earthquake

Geologic map of the McCoy mining district, Lander County, Nevada

Geologic map of the Caetano caldera, Lander and Eureka counties, Nevada

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

New Geologic Map – Kinsley Mountains

Preliminary Geologic Map of the Kinsley Mountains, Elko and White Pine Counties, Nevada
Authors: John L. Muntean, Seth Dee, Tyler J. Hill, Randall L. Hannink, Moira Smith, Gene Urie, and Ken Raabe
Year: 2017
Series: Open-File Report 2017-07
Version: first edition, September 2017; supersedes Open-File Report 15-9
Format: plate: 41 x 54.5 inches, color; text: 5 pages, b/w
Scale: 1:12,000

This detailed geologic mapping of the Kinsley Mountains in eastern Nevada investigates the time-space relationships between an Eocene intrusive complex centered on a granitic stock, proximal intrusion-related polymetallic skarn and carbonate replacement mineralization, disseminated Carlin-style gold deposits 3 km north of the stock, Eocene magmatism, and Eocene through Quaternary faulting. Previous detailed mapping of the northern Kinsley Mountains by geologists of Pilot Gold was compiled, field checked, and refined, along with new mapping during the summers of 2015 and 2017. Pilot Gold is exploring for more Carlin-style mineralization in the center of the range and map area, where gold ore was previously mined in the late 1990s. The mapping revealed: 1) a significant amount of extensional faulting occurred prior to Eocene magmatism and mineralization, similar to what NBMG mapping documented recently in the Eureka mining district. Eocene intrusions cut faults or fill faults, and Eocene volcanic rocks unconformably overlie Paleozoic rocks as old as Ordovician and as young as Permian, 2) Eocene dikes, gossans, and quartz veins, and jasperoid formation are focused within a 1-km-wide corridor that extends 3 km northward from the stock to the area of carbonate-hosted Carlin-like gold deposits, where dikes in drill core have locally high gold grades, 3) significant Eocene extension is demonstrated by a southwest-dipping fault that dropped Permian rocks against metamorphosed and mineralized Cambrian rocks proximal to the Eocene stock; the fault is overlapped by Eocene volcanic rocks that are a few million years younger than the stock, suggesting the intrusive complex was rapidly exhumed nearly 3 km, and 4) detailed mapping of the Quaternary range front fault on the east side of the mountains demonstrates offset of alluvial-fan deposits of likely mid-Pleistocene age with no faulting in younger Quaternary deposits.

This map was prepared as a part of the STATEMAP component of the National Cooperative Geologic Mapping Program in cooperation with the U.S. Geological Survey under STATEMAP award number G16AC00186, 2017.

New Geologic Map – Independence Valley NW

Preliminary Geologic Map of the North Half of the Independence Valley NW Quadrangle and the Adjacent Part of the Independence Valley NE Quadrangle, Elko County, Nevada
Author: Seth Dee, Christopher D. Henry, Michael W. Ressel, and Andrew V. Zuza
Year: 2017
Series: Open-File Report 2017-06
Version: first edition, September 2017
Format: plate: 35 x 30.5 inches, color; text: 4 pages, b/w
Scale: 1:24,000

The north half of the Independence Valley NW 7.5-minute quadrangle covers a part of the western Pequop Mountains and adjacent Independence Valley in eastern Elko County. The east-tilted Pequop Mountains have newly recognized Carlin-type gold deposits in a geographic and geologic setting distinct from similar deposits elsewhere in Nevada. Mapping in the quadrangle was done in the summer of 2017.

Southeast-dipping Cambrian through Ordovician sedimentary rocks are exposed in the range front along the eastern edge of the map area. Eocene rhyolite dikes and sills, and Cretaceous granitic sills and pods locally intrude the oldest Cambrian stratigraphy. The Eocene intrusions may be part of a magmatic system that produced the heat source for the nearby Carlin-type mineralization. The range front is bound on the west by two west-dipping normal fault systems that accommodated late Cenozoic exhumation. Exposed in the hanging wall of the eastern fault system are late Cenozoic basin deposits that uncomfortably overlie Cambrian through Ordovician sedimentary rocks. Logs from three boreholes drilled into the Paleozoic rocks of the hanging wall during mineral exploration were used to help develop cross section A–A’’. One of the boreholes encountered an approximately 60-m-thick zone of fault gouge and a fault sliver with repeated Ordovician stratigraphy. This fault zone is interpreted to place Permian Pequop Formation above Ordovician Fish Haven Dolomite and may be correlative with the enigmatic Pequop fault observed in the adjacent Pequop Summit and Independence Valley NE quadrangles and variably interpreted as a thrust (Thorman, 1970) or a low-angle normal fault (Camilleri, 2010). Another borehole was advanced through the eastern range-front fault and constrains the dip of the fault to 34° west. Correlation of stratigraphy across the eastern range-front fault suggests approximately 4 km of total dip-slip displacement during Cenozoic exhumation.

The oldest Cenozoic basin deposits exposed between the two range front fault systems are tuffaceous sediments with a maximum measured bedding dip of 34° east. The tuffaceous sediments are overlain by a megabreccia landslide deposit with individual bedrock blocks over 200 m long. The individual blocks have lithologic and textural characteristics similar to rocks exposed along the western flank of the modern Pequop Mountains, which may have been the source of these megabreccia deposits. The megabreccia is overlain by Pliocene(?) fanglomerate deposits with nearly horizontal bedding.

The western range-front fault, named the Independence Valley fault zone, has evidence for late-Quaternary activity. In the footwall of the fault, alluvial-fan deposits of probable middle Pleistocene age are beveled onto the Cenozoic sediments. Late Quaternary displacement along the Independence Valley fault zone has uplifted these fan deposits a minimum of 30 m. The youngest fan deposits offset by the fault zone are of probable latest Pleistocene age, and are displaced by fault scarps up to 3 m high.

In Independence Valley, lacustrine gravels are deposited on shorelines, beach bars, and spits recording the high-stand and recessional stages of latest Pleistocene Lake Clover (Munroe and Laabs, 2013). An older lacustrine gravel deposit with a well-developed pedogenic carbonate soil horizon was mapped topographically above the latest Pleistocene shorelines along the western edge of the map area.

This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G16AC00186, 2017.

New Geologic Map – Boulder City NW

Preliminary Geologic Map of the Boulder City NW Quadrangle, Clark County Nevada
Author: Nicholas H. Hinz, Seth Dee, and Racheal Johnsen
Year: 2017
Series: Open-File Report 2017-05
Version: first edition, September 2017
Format: plate: 41 x 41.5 inches, color; text: 5 pages, b/w
Scale: 1:24,000

This 1:24,000-scale preliminary geologic map of the Boulder City NW 7.5-minute quadrangle in Clark County, Nevada covers portions of the southwestern River Mountains, the northeastern McCullough Range and straddles a segment of the drainage divide between the hydrologically closed Eldorado Valley and Las Vegas Valley which is part of the through-flowing Colorado River Basin. The City of Henderson extends into the north-central part of this quadrangle, and the in-progress Interstate 11, Boulder City Bypass transects the northeastern part of the quadrangle.

The bedrock exposures in the quadrangle include Tertiary plutonic, volcanic, and sedimentary rocks. The northeastern McCullough Range includes the ~14.5- to 13.8-Ma Railroad Pass pluton and corresponding ~15.0- to 13.9-Ma Dutchman Pass volcanics. The southwestern River Mountains is dominated by the pervasively hydrothermally altered Red Mountain volcanics. The Red Mountain volcanics are locally intruded by the ~14.5- to 13.5-Ma Boulder City pluton and locally overlain by the Dutchman Pass, Powerline Road, and Mount Davis volcanics.

The bedrock in the southern River Mountains contains numerous southerly strands of the dextral, NW-striking Las Vegas Valley shear zone, and the sinistral, NE-striking Lake Mead fault system, both major crustal structures during Miocene regional extension. The bedrock in the northeastern McCullough Range is cut by a system of kinematically linked north-striking, down-to-east normal faults and NW-striking dextral faults, the latter of which are associated with part of the southern termination of the Las Vegas Valley shear zone. The east side of the northern McCullough Range is bound by the Black Hills fault, which is an active range-front normal fault expressed as a continuous, 1.8- to 2.8-m-high fault scarp in late Pleistocene fan deposits. Mapping at the north end of the Black Hills fault suggests that the fault is directly linked to the sinistral, NE-striking Hemenway Wash fault, which is a major strand of the Lake Mead fault system, and that locally bounds the southern flank of the River Mountains. In contrast to the Black Hills fault, Quaternary fault scarps were not observed along the Hemenway Wash fault.

Surficial sediments in the quadrangle are largely alluvial fan and pediment deposits ranging from historic to early Pleistocene. Fan deposits eroded from altered Railroad Pass pluton locally contain clasts with actinolite and magnesiohornblende, which are naturally occurring asbestos (NOA) minerals.

This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G16AC00186, 2017.