Geology topics
Research about Nevada
Source-linked reports with geographic coverage including Nevada.
Principle facts for gravity stations in Lemmon Valley, Washoe County, Nevada
No abstract available.
Water-resources data collected in the Devils Hole area, Nye County, Nevada, 1977-1978
This report presents water data collected at Devils Hole and vicinity for July 1977 through June 1978 to observe the effects of irrigation pumping on the pool level in Devils Hole. The pool contains the endangered species of pupfish, Cyprinodon diabolis . The report presents data on fluctuations in water level and springflow in graphic form and tabulates electrical energy consumed by irrigation wells as an index of the pumpage.
Stratigraphy, petrology, and some fossil data of the Roberts Mountains Formation, north-central Nevada
Silty laminated very fine grained carbonate is the host rock for the large gold-ore deposits at the Carlin and Cortez mines. After setting out the geological setting of the Formation, and the methods of study, the stratigraphy and petrology of the Formation are examined in detail, followed by the age of the formation, its correlation, environment of deposition, source of its detrital material, its trace elements and gold deposits
Crystals of coexisting alunite and jarosite, Goldfield, Nevada
Alunite (KAl 3 (SO 4 ) 2 (OH) 6 ) and jarosite (KFe 3 (SO 4 ) 2 (OH) 6 ) coexist in optically continuous crystals in a sample from the Goldfield mining district, Esmeralda County, Nev. Beam scans with an electron microprobe indicate that no intermediate minerals of the solid-solution series alunite-jarosite occur in these crystals. An Eh-pH diagram demonstrating the equilibrium relations between alunite, jarosite, and geothite suggests the crystals most likely developed by a rise in Eh, which oxidized ferrous to ferric iron, thus allowing jarosite to precipitate.
Spectra of altered rocks in the visible and near infrared
Visible and near-infrared (0.35 to 2.5 mu m) bidirectional reflection spectra were recorded for a suite of well-characterized hydrothermally altered rock samples. The spectra typically display well-defined bands caused by both electronic and vibrational processes in the individual mineral constituents.Electronic transitions in the iron-bearing constituent minerals produce diagnostic minima near 0.43, 0.65, 0.85, and 0.93 mu m. Vibrational transitions in clay and water-bearing mineral constituents typically produce characteristic single or multiple features over limited spectral ranges near 1.4, 1.75, 1.9, 2.2, and 2.35 mu m. The most abundant feature-producing minerals present in these rocks are hematite, goethite, and alunite, while others frequently present are jarosite, kaolinite, potassium micas, pyrophyllite, montmorillonite, diaspore, and gypsum.This study shows that visible-near infrared spectrometry is a reliable and rapid technique for detecting and identifying clay minerals and alunite in rocks. Because these minerals are important constituents of altered rocks, the feasibility of using the visible and near infrared for detecting altered rocks by remote-sensing techniques is indicated. The spectral region near 2.2 mu m is particularly important for this purpose.
Strain pattern represented by scarps formed during the earthquakes of October 2, 1915, Pleasant Valley, Nevada
The pattern of scarps developed during the earthquakes of October 2, 1915, in Pleasant Valley, Nevada, may have formed as a result of a modern stress system acting on a set of fractures produced by an earlier stress system which was oriented differently. Four major scarps developed in a right-stepping, en-echelon pattern suggestive of left-lateral slip across the zone and an extension axis oriented approximately S85°W. The trend of the zone is N25°E. However, the orientation of simple dip-slip on most segments trending approximately N20—40° E and a right-lateral component of displacement on several N- and NW-trending segments of the scarps indicate that the axis of regional extension was oriented between N50° and 70° W, normal to the zone. The cumulative length of the scarps is 60 km, average vertical displacement 2 m, and the maximum vertical displacement near the Pearce School site 5.8 m. Almost everywhere the 1915 scarps formed along an older scarp line, and in some places older scarps represent multiple previous events. The most recent displacement event prior to 1915 is interpreted to have occurred more than 6600 years ago, but possibly less than 20,000 years ago. Some faults expressed by older scarps that trend northwest were not reactivated in 1915, possibly because they are oriented at a low angle with respect to the axis of modern regional extension. The 1915 event occurred in an area of overlap of three regional fault trends oriented northwest, north, and northeast and referred to, respectively, as the Oregon—Nevada, Northwest Nevada, and Midas—Battle Moutain trends. Each of these trends may have developed at a different time; the Oregon—Nevada trend was possibly the earliest and developed in Late Miocene time (Stewart et al. 1975). Segments of the 1915 scarps ar
Preliminary geologic and geophysical data of the UE25a-3 exploratory drill hole, Nevada Test Site, Nevada
The UE25a-3 drill hole, located in the Calico Hills area, southwestern part of the Nevada Test Site, was drilled as part of an effort to evaluate the Calico Hills area as a possible nuclear waste repository site. The purpose of the drill hole was to verify the existence of an intrusive crystalline body in the subsurface and to determine the stratigraphy, structure, and nature of fractures of the cored rocks. Cored samples were obtained for mineral, chemical, and material property analyses. Continuous cores were taken from 30.5 m (100ft) to total depth of 771.2 m (2,530.1 ft) of units J and I{?) (Late Mississippian age) of the Eleana Formation. The drill hole penetrated 416.1 m (1 ,365ft) of argillite, and 304.5 m (999ft) of thermally altered argillite of unit J, and 50.6 m (166ft) of marble of unit I(?). No crystalline rocks were intersected by the drill hole. Numerous high-angle faults and brecciated zones were intersected by the drill hole. The units cored were intensely fractured with fracture analysis of the core consisting of frequency of fractures, dips of fractures, open and closed (sealed) fractures and types of fracture sealing or coating material. Twenty-four hundred and thirty fractures, representing approximately 30 percent of the fractures present, indicate an average fracture frequency of 13.2 fractures per meter, predominantly high-angle dips with 66 percent of the fractures closed. Fractures in the argillite interval are sealed or coated predominantly with kaolinite, nacrite, and dickite. Calcite, chlorite, and magnetite are present in fractures in the altered argillite interval. Fractures in the marble interval are sealed or coated with calcite, dolomite, and ferruginous clay. The core index indicates that the lower half of the drilled interval is more competent than the upper half. Borehole geophysical logs were run by the Birdwell Division of Seismograph Service Corporation for geologic correlations and lithologic characterizations. The logs include: caliper, density, resistivity, spontaneous potential, Vibroseis, 3-D velocity, neutron, and gamma-ray logs. Lithologic boundaries and structures correlate to responses in the logs.
Aeromagnetic and generalized geologic map of the Paradise Range area, Nevada
No abstract available.
Geologic map of Miller Mountain and Columbus quadrangles, Mineral and Esmeralda Counties, Nevada
No abstract available.
Map of young fault scarps related to earthquakes in north central Nevada
No abstract available.
Accessory opaque oxides from hybrid granitoid rocks of the southern Snake Range, Nevada
Analytical data are presented for 12 magnetite and 6 ilmenite samples recovered from hybrid granitoid rocks of the southern Snake Range, Nevada. The magnetites are unusual for their very low contents of TiO 2 and for their similarity of composition over a range of petrologic types. The ilmenites are somewhat unusual for their high contents of MnO. Most of the titanium in these hybrid granitoid rocks is contained in biotite and sphene.
Data on ground-water resources of the Spring Mountains area, Toiyabe National Forest, Nevada
This report lists data on ground-water levels for 16 wells and discharge for 18 springs in the Spring Mountain area of the Tolyabe National Forest. Water levels in wells ranged from 325 to 519 feet below land surface. The highest spring discharge listed is 107 gallons per minute. In addition, data on the chemical quality of the water from selected wells and springs are listed.