Tag Archive | Maps

New Geologic Map—Red Ridge Area, Churchill and Mineral Counties

Preliminary Geologic Map of the Red Ridge Area, Churchill and Mineral Counties, Nevada
Author: Chad W. Carlson
Year: 2017
Series: Open-File Report 2017-02
Format: plate: 35.5 x 28 inches, color; text: 7 pages, color
Scale: 1:24,000
Free download/purchase: http://pubs.nbmg.unr.edu/Prel-geol-Red-Ridge-area-p/of2017-02.htm

The Walker Lane accommodates dextral motion between the northwest translating Sierra Nevada microplate to the west and Basin and Range extension to the east. A significant portion of dextral shear in the central Walker Lane is accommodated on left-stepping, en echelon, northwest-striking fault systems that compose the Walker Lake domain. Northwest of these dextral faults, strain is transferred to sinistral faults accommodating oroclinal flexure and clockwise-rotation of blocks in the Carson domain of the northern Walker Lane. Positioned at the northern terminus of the Walker Lake domain, the Red Ridge area resides southeast and in right-lateral separation across the Benton Spring fault from the Terrill Mountains. The thick Oligocene to late Miocene volcanic strata of the Red Ridge area provide opportunity to examine Tertiary strata and styles of deformation and correlate to results of recent geologic mapping completed in the adjacent Terrill Mountains quadrangle. Detailed geologic mapping of the Red Ridge area was completed to help elucidate the Neogene styles of, and transitions in, strain accommodation for this region of the Walker Lane.

Geologic mapping of the Red Ridge area greatly elucidated the stratigraphic and structural framework of Red Ridge and expanded understanding of deformation at the northern termination of the Walker Lake domain. The Tertiary strata included late Oligocene ash-flow tuffs and Miocene volcanic rocks correlated to, and dextrally offset from, Terrill Mountains stratigraphy. Several ash-flow tuffs correlate with regionally extensive units and provide opportunity for future paleomagnetic study. Similar to the southern Terrill Mountains, northeasterly-striking normal faults appear kinematically linked to major northwest-striking dextral faults and accommodate diffusion of dextral strain and basin development. The detailed mapping of the Red Ridge area has provided a firm foundation for future structural analysis and paleomagnetic study of the region.

This map was partially funded by the National Science Foundation.

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New Geologic Map—Bradys Geothermal Area, Churchill County

Preliminary Geologic Map of the Bradys Geothermal Area, Churchill County, Nevada
Authors: James E. Faulds, Alan R. Ramelli, Mark F. Coolbaugh, Nicholas H. Hinz, Larry J. Garside, and John H. Queen
Year: 2017
Series: Open-File Report 2017-04
Format: plate: 51 x 39 inches, color, with cross sections; text: 6 pages, color
Scale: 1:12,000
Free download/purchase: http://pubs.nbmg.unr.edu/Prel-geol-Bradys-geothermal-p/of2017-04.htm

The Bradys geothermal field lies in the northern Hot Springs Mountains ~80 km northeast of Reno in Churchill County, Nevada.  The field has a reservoir temperature of 180-193°C at 1- to 2-km depth and currently supports a combined dual flash and binary geothermal power plant with a total installed capacity of 26 MWe, as well as a vegetable dehydration plant.  The power plant has been in operation since 1992.  The detailed geologic map and cross sections of the Bradys geothermal field illustrate the linkages between permeability and a complex structural setting dominated by a left step in a normal fault zone but also including several fault intersections within a broader accommodation zone.  Seismic reflection data and re-logging of cuttings and core from 34 wells were incorporated into the cross sections.  A previously published 1:24,000-scale geologic map of the Desert Peak quadrangle only included the easternmost part of the Bradys geothermal field.  The purpose of this map is to show the entire geothermal field at a finer scale (1:12,000) sufficient to illustrate multiple geothermal features, such as the complex faulting, sinter, warm ground, and fumaroles.  Unpublished versions of this map and cross sections have served as the foundation for previously published, 3D structural modeling and 3D gravity inversion of the Bradys geothermal field.

This project was supported by the U.S. Department of Energy, Ormat Technologies, Inc., and the U.S. Geological Survey STATEMAP Program.

Nevada Active Mines and Energy Producers

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Authors: John L. Muntean and David A. Davis
Year: 2017
Series: Educational Series 60
Version: supersedes Educational Series 49 and 54
Format: 11 x 17 inches, color
Scale: 1 inch = 4 miles
View/download here: http://pubs.nbmg.unr.edu/NV-active-mines-and-energy-2016-p/e060.htm

Site locations and information on this map were obtained from a variety of published and non-published sources with the last updates made in January 2017. All sites shown on this map have had some form of production activity during 2016.

This map was prepared in cooperation with the Nevada Division of Minerals.

Job Announcement from Washington Division of Geology and Earth Resources—Geologist/Editor—ends TODAY (Jan. 31)

The position of Geologist/Editor is available at the Washington State Geological Survey in Olympia.

Here is the job description:
https://www.governmentjobs.com/jobs/1627086/editor-geologic-information-nr-scientist-3

For more information, contact:
Jessica Czajkowski
GIS/Editing Section Manager
Division of Geology and Earth Resources
1111 Washington St. SE, MS47007
Olympia, WA 98501
Jessica.czajkowski@dnr.wa.gov
360-902-1117

New Geologic Maps in Northern Nevada: Mount Rose NW and Herder Creek Quadrangles

 

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Preliminary Geologic Map of the South Half of the Mount Rose NW Quadrangle, Washoe County, Nevada

 Authors: Nicholas H. Hinz and Alan R. Ramelli
Year: 2016
Series: Open-File Report 16-6
Format: plate: 35 x 29 inches, color; text: 3 pages, b/w
Scale: 1:24,000
View/Download/Buy: http://pubs.nbmg.unr.edu/Geol-south-half-Mount-Rose-NW-p/of2016-06.htm

This quadrangle straddles the north end of the Carson Range directly west-southwest of Reno and abuts the Nevada-California border. The Truckee River and Interstate 80 transect the northwest quarter of this quadrangle. This quadrangle also encompasses part of the rural community along Thomas Creek in the southeast quarter, and segments of the Steamboat irrigation ditch and part of the City of Reno urban area fall within the northeast corner.

The bedrock exposures in the quadrangle consist of Mesozoic granitic basement and Tertiary volcanic and sedimentary rocks. The Tertiary section includes a complex section of lavas, intrusions, and volcanic sedimentary rocks. Many of these volcanic and sedimentary rocks were derived from a ~6-7 Ma ancestral Cascades volcanic center in the Mount Rose quadrangle, directly south of this quadrangle. Plio-Pleistocene basaltic andesite lavas and rhyolite domes locally rest on the late Miocene volcanic rocks in the middle part of the quadrangle. Principal surficial deposits include late Pliocene to modern alluvial fan and fluvial deposits, Quaternary glacial deposits, and late Quaternary mass wasting deposits. Notable deep-seated landslide complexes reside in all major drainages—including Thomas Creek, Hunter Creek, Bronco Creek, and the smaller catchments along the west edge of the quadrangle. Most of the Carson Range is west-tilted with west-dipping Cenozoic strata. However, within the Mount Rose NW quadrangle, the dip domain flips and most all the Cenozoic strata dips east with numerous west-dipping normal faults. These west-dipping normal faults are cut by younger east-dipping normal faults of the Mount Rose fault zone on the east side of the range.  East-facing Quaternary fault scarps were observed on the east side of the range and west-facing Quaternary fault scarps were observed on the west side of the range.

This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G15AC00240, 2016.

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Preliminary Geologic Map of the Herder Creek Quadrangle, Elko County, Nevada
Author: Seth Dee and Michael W. Ressel
Year: 2016
Series: Open-File Report 16-5
Format: plate: 33 x 29 inches, color; text: 5 pages, b/w
Scale: 1:24,000
View/Download/Buy: http://pubs.nbmg.unr.edu/Prel-geol-Herder-Creek-quad-p/of2016-05.htm

The map area covers part of Starr Valley, the upper reaches of the Humboldt River, and the northwest part of the East Humboldt Range.

The Ruby Mountains–East Humboldt Range metamorphic core complex is exposed in the high-relief range front in the southeast part of the quadrangle. In this area, the core complex is comprised of intensely metamorphosed and highly attenuated Neoarchean through Mississippian(?) strata, thought to be part of the platform facies of the Proterozoic through Paleozoic passive margin. Contractional structures exposed in the map area are complex and difficult to discern due to overprinted extensional deformation but are likely part of the Winchell Lake nappe (WLN), a kilometer scale, southward-closing recumbent fold-nappe mapped in adjacent quadrangles to the east. Overturned Devonian to Neoproterozoic(?) meta-sedimentary strata exposed at the highest structural levels are interpreted to be in thrust contact with an underlying, upright sequence of Cambrian to Neoproterozoic(?) paragneiss and Paleoproterozoic to Neoarchean(?) orthogneiss in the core of the fold. This structural interpretation matches those from the adjacent Welcome quadrangle (McGrew and Snoke, 2015; NBMG Map 184). Rocks in the upper part of the metamorphic core complex are pervasively overprinted by a WNW-directed mylonitic shear fabric, which records middle to late Cenozoic extensional exhumation from mid-crustal depths. Abundant sills and lenses of less deformed Oligocene to Cretaceous garnet-muscovite leucogranite and biotite monzogranite intrude all metamorphic rocks in the quadrangle.

The west side of the East Humboldt Range is bound by the active, W-dipping Ruby Mountains frontal fault zone, which extends for more than 60 km to the southwest. A west step-over in the Ruby Mountains fault south of the Herder Creek drainage results in a broad, hanging wall uplift underlain by middle-Miocene to Pliocene strata comprised of NE-dipping to flat-lying tuffaceous sandstone, shale, and conglomerate of the Humboldt Formation and younger units. A tephra in the uppermost exposed section yielded a 40Ar/39Ar age on feldspar of 5.15 ± 1.82 Ma.

Repeated late Quaternary surface-rupturing earthquakes along active traces of the frontal fault are recorded by increased uplift and dissection of Quaternary surfaces as a function of relative age. Fault scarps in Holocene deposits have up to 2.5 m of vertical separation while glacial outwash deposits from the two most recent Pleistocene glacial advances have scarp heights ranging from 6 to 32 m. The upper reaches of several drainages have well-preserved glacial moraine deposits that record the Angel Lake and Lamoille glacial advances. Adjacent to the Humboldt River, in the northwest corner of the quadrangle, 3 sets of abandoned terrace surfaces are preserved, including a broad surface comprised of gravel-rich alluvium that was likely deposited during a period of increased discharge during the latest Pleistocene.

This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G15AC00240, 2016.

New Geologic Maps in Clark County: Boulder City and Apex Quadrangles

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Preliminary Geologic Map of the Boulder City Quadrangle, Clark County, Nevada

Authors: Seth Dee, Nicholas H. Hinz, R. Ernie Anderson, and Racheal Johnsen
Year: 2016
Series: Open-File Report 16-4
Format: plate: 39 x 29 inches, color; text: 6 pages, some color
Scale: 1:24,000
View/Download/Buy: http://pubs.nbmg.unr.edu/Prel-geol-Boulder-City-quad-p/of2016-04.htm

 A 1:24,000 scale preliminary geologic map of the Boulder City 7.5-minute quadrangle in Clark County, Nevada. This quadrangle covers portions of the southeastern River Mountains, the northern Eldorado Mountains and straddles a segment of the drainage divide between the hydrologically closed Eldorado Valley and the through-flowing Colorado River Basin. Boulder City is located in the northern part of the quadrangle, as is the in-progress Interstate 11, Boulder City Bypass. This publication includes a combination of new mapping and integration with existing mapping by Ernie Anderson.

The bedrock exposures in the quadrangle are dominated by Tertiary plutonic, volcanic, and sedimentary rocks with lesser Proterozoic metamorphic rocks and Paleozoic sedimentary rocks. In the northern Eldorado Mountains the basal volcanic section includes the early to middle Miocene, intermediate to felsic composition Patsy Mine volcanics. The Patsy Mine volcanics are locally intruded by the composite, middle Miocene Boulder City pluton. This pluton is variably hydrothermally altered with actinolite present in altered groundmass and fracture-fill veins. Both the Boulder City pluton and the Patsy Mine volcanics are locally overlain by the middle Miocene Mount Davis volcanics which consist of a syn-extensional, bimodal sequence of lavas and tuffaceous sediments. In the southeastern River Mountains, the Tertiary strata are dominated by the middle Miocene, intermediate to felsic composition Red Mountain volcanics. These rocks are intruded by a middle Miocene granitic stock, which is probably related to widespread hydrothermal alteration of the Red Mountain volcanics. Locally overlying the Red Mountain volcanics are the less altered, intermediate to silicic, volcanics of Bootleg Wash, and unaltered Mount Davis volcanics.

The bedrock in the northern Eldorado Mountains is faulted by numerous north-striking, down-to-east and down-to-west normal faults. The northeast-striking, sinistral Hemenway Wash fault transects the northwest quarter of the quadrangle, separating the Eldorado Mountains from the River Mountains. The Hemenway Wash fault is one of the faults that makes up the >100 km-long, Lake Mead Fault System. In the northernmost Eldorado Mountains, fault strikes curve from N-S to NW and to E-W as they approach the Hemenway Wash fault zone, possibly due to oroclinal flexure. Provisional analysis of new geochronologic and geochemical data acquired in this study indicate that the plutonic and volcanic strata exposed in the southeastern River Mountains may correlate directly to strata in the northern Eldorado Mountain, providing a means to evaluate a range of possible displacements across the Hemenway Wash fault.

Surficial sediments in the quadrangle are largely alluvial fan and pediment deposits ranging from historic to Pliocene in age. Early Pleistocene to late Pliocene surficial deposits are characterized by 2+ m thick pedogenic carbonate horizons, which form resistant geomorphic surfaces on the east side of the Eldorado basin and cap many of the bedrock highlands in the Eldorado range. Fan deposits eroded from altered Boulder City plutonic rocks or from Miocene basin sediments may contain redistributed actinolite-bearing clasts. One possible fault scarp was observed in a late to middle Pleistocene aged fan. No other evidence for Quaternary faulting was recognized in the quadrangle.

This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G15AC00240, 2016.

apexPreliminary Geologic Map of the Apex Quadrangle, Clark County, Nevada

Author: Robert G. Bohannon
Year: 2016
Series: Open-File Report 16-3
Format: plate: 31 x 32 inches, color; text: 5 pages, color
Scale: 1:24,000
View/Download/Buy: http://pubs.nbmg.unr.edu/Prelim-geol-Apex-quad-p/of2016-03.htm

The Apex quadrangle (1:24,000 scale) is centered approximately 22.5 km northeast of downtown Las Vegas in Clark County, Nevada. Rocks in the quadrangle are exclusively sedimentary and include a mostly conformable sequence of Paleozoic continental shelf and platform rocks in its north half. The south half of the quadrangle is mostly Miocene interior-continental-basin deposits. Dissected alluvial deposits of Quaternary and latest Tertiary age, only the oldest of which are consolidated, discontinuously cover large lowland parts of the quadrangle. The Paleozoic rocks are deformed and in some places overturned by Mesozoic thrust faults associated with the Late Cretaceous Sevier Orogenic disturbance. A large east-vergent thrust fault with a northeast orientation, the Dry Lake Thrust, cuts the eastern half of the quadrangle, where it is mostly concealed by post-Cretaceous deposits. The thrust juxtaposes lower Paleozoic shelf rocks in the hanging wall above upper Paleozoic continental platform rocks in the footwall. Tertiary normal faults are also common and are mostly oriented northeast where they cut Paleozoic rocks. The Miocene beds, most of which post-date the northeast normal faults, are deformed by a few east-west or east-northeast-oriented faults and numerous small folds that are associated with them. The younger faults might be associated with very late-stage movement on the Las Vegas Valley shear zone which projects into the quadrangle from beneath Las Vegas Valley to the east, but the shear zone is otherwise concealed by the Miocene deposits.

Publication Sales and Information Office Closed December 26–30, 2016

GBSSRL_March_2014_Jack_Hursh

NBMG’s Great Basin Science Sample and Records Library (aka “The Gold Building”) at 2175 Raggio Parkway in Reno.

The Publication Sales and Information Office at Great Basin Science Sample and Records Library will be closed the week of December 26–30, 2016.

No orders will be filled during this time period. If you will need any publications before January 3, 2017, please place those orders by December 20 to give us time to fill them before the week that we are closed.

We will be open our normal hours again on Tuesday January 3, 2017. We apologize for this inconvenience.