Identification of Quartz and Carbonate Minerals Across Northern Nevada

Home , Diamond Peak (Colorado), Jasperoid, Vinini Formation

Identiﬁ cation of quartz and carbonate minerals across northern Nevada using ASTER thermal infrared emissivity data—Implications for geologic mapping and mineral resource investigations in well-studied and frontier areas

Barnaby W. Rockwell* Albert H. Hofstra U.S. Geological Survey, Box 25046, MS 973, Denver Federal Center, Denver, Colorado 80225, USA

ABSTRACT posed primarily of other minerals, they were carbonate mapping demonstrated here can inferred to be hydrothermal in origin and be used in well-studied or frontier areas to ASTER (Advanced Spaceborne Thermal compared to known occurrences of hydro- verify the accuracy of existing geologic maps, Emission and Refl ection Radiometer) ther- thermal alteration and mineralization. guide future detailed stratigraphic and struc- mal infrared imagery over a 389 km × 387 The ASTER-based quartz mapping iden- tural mapping in lithologically complex ter- km area in northern Nevada (38.5°–42°N, tifi ed thick sequences of quartzite, bed- ranes and allochthons, and identify hydro- 114°–118.5°W) was analyzed to evaluate its ded radiolarian chert, quartz sandstone, thermal features for exploration and resource capability for accurate and cost-effective conglomerates with clasts of quartzite and assessment purposes. identifi cation and mapping of quartz and chert, silicic and/or altered rhyolites, and carbonate minerals at regional to local scales. silicic welded tuffs. Alluvial fan surfaces, Keywords: remote sensing, ASTER, thermal The geology of this area has been mapped at sand dunes, and beach deposits composed infrared, quartz, carbonate. a wide range of scales and includes a diver- of quartz and/or carbonate are prominent, sity of rock types and unconsolidated surfi - well-mapped features. Quartz was also iden- INTRODUCTION cial materials, many of which are composed tifi ed in smaller bodies of jasperoid, quartz- primarily of quartz and carbonate minerals. alunite, and quartz-sericite-pyrite alteration, The Great Basin physiographic province is This area is also endowed with a wide vari- hot spring silica sinter terraces, and several the world’s second leading producer of gold ety of economically and scientifi cally impor- diatomite and perlite mines and prospects. and is also host to a wide variety of ore deposits tant ore deposit types that contain an array The ASTER-based carbonate mapping iden- that contain large resources of silver, base met- of commodities (Au, Ag, Pb, Zn, Cu, Mo, W, tifi ed thick sequences of dolomite, limestone, als, and other important metallic and industrial Sn, Be, F, Mn, Fe, Sb, Hg, and barite). The and marble, as well as small hot spring trav- minerals (Hofstra and Wallace, 2006). Because hydrothermal systems that generated these ertine deposits. Eolian carbonate was identi- hydrothermal silicifi cation accompanies miner- deposits frequently deposited large amounts fi ed in several playas. Dolomite exhibited a alization in many metal deposits, the identifi ca- of quartz where fl uids cool, and generally stronger carbonate response than calcite, as tion and mapping of quartz in rocks composed smaller amounts of calcite or dolomite by predicted based on their thermal spectral mainly of other minerals is of great value for other mechanisms. characteristics. Quartz was detected at lower exploration and assessments of resource poten- To identify and map quartz and carbon- concentrations than carbonates because of tial. Identifi cation of quartz and carbonate in ate minerals, band ratioing techniques were the greater strength of the quartz reststrahlen rocks and unconsolidated surfi cial materials developed based on the shapes of laboratory features in the thermal infrared compared to across large areas holds promise for assessing the reference spectra and applied to ASTER the bending-related spectral features of car- potential for industrial rock-mineral resources Level 2 surface emissivity products of 108 bonates. The 90 m ground pixel size of the including aggregate, sand, gravel, caliche, and overlapping scenes. These mineral maps ASTER thermal imagery prevents the iden- calcrete. The regional mapping of these miner- were mosaicked into a single coverage that tifi cation of small-scale features. Despite this als also facilitates evaluation of existing geo- was overlain with published, vector-format limitation, numerous bodies of hydrothermal logic maps and recognition of locales in need of geologic maps of various scales to determine quartz were detected in or near known Car- more refi ned mapping or topical investigation. which geologic terranes, formations, and lin-type gold deposits, distal disseminated Data from spaceborne remote sensing systems geomorphic features correspond to identifi ed Au-Ag deposits, high- and low-sulfi dation have been applied to prospecting in terranes quartz or carbonate. Where quartz or car- epithermal Au-Ag deposits, and geothermal with requisite geologic and tectonic frameworks bonate minerals were mapped in rocks com- areas. Detection of hydrothermal carbonate for decades, but the Advanced Spaceborne was rare and mainly in geothermal areas. Thermal Emission and Refl ection Radiometer The ASTER-based thermal quartz and (ASTER) sensor aboard the Earth Observing *[email protected].

Geosphere; February 2008; v. 4; no. 1; p. 218–246; doi: 10.1130/GES00126.1; 17 ﬁ gures; 3 tables; 3 plates, 2 supplemental index maps.

System (EOS) Terra satellite launched in 2000 TABLE 1. MEASURED SPECTRAL emissivity “absorption” features. As the labora- provides revolutionary new capabilities for cost- PERFORMANCE OF ASTER THERMAL tory spectra were measured in biconical, rather INFRARED BANDS effective mineral and landcover mapping over than hemispherical, reﬂ ectance, the generated Central large areas. The ASTER sensor acquires multi- ASTER Band width emissivity spectra can be used to predict only wavelength band (µm) spectral data in 14 bands, including 5 bands in (µm) the spectral shapes, and not absolute emissiv- the mid-infrared, or thermal (8–14 µm), region 10 8.291 0.344 ity values, of the mineral spectra. In both Fig- of the electromagnetic spectrum, in addition to 11 8.634 0.347 ures 1 and 2, the emissivity spectra convolved another band with backward-looking geometry 12 9.075 0.361 to ASTER sampling and bandpass are shown in the near-infrared (NIR, 0.76–0.86 µm) to pro- 13 10.657 0.667 in red. In Figure 1, the emissivity absorption 14 11.318 0.593 vide capability for stereoscopic observation and Note: Data from ASTER (Advanced features of quartz at ASTER bands 10 and 12 digital elevation model generation. The multi- Spaceborne Thermal Emission and are related to fundamental asymmetric Si-O spectral thermal infrared (TIR) data of ASTER Reflection Radiometer) User’s Guide (Earth stretching vibrations (reststrahlen bands). The are vital for detecting nonhydrous varieties of Remote Sensing Data Analysis Center, reststrahlen bands of quartz are the strongest quartz that are not spectrally identiﬁ able in the 2005). of any silicate mineral (Salisbury and D’Aria, visible, near-infrared, and shortwave-infrared 1992b). In Figure 2, the emissivity absorption (SWIR, 1.4–2.5 µm) spectral regions because features of calcite and dolomite at ASTER band of a lack of diagnostic absorption features. The shows the wavelength centers and band widths 14 are related to out-of-plane bending modes of

ASTER TIR data also provide capability for the of the fi ve ASTER thermal bands, which have the CO3 ion (Clark, 1999). Note that dolomite remote identifi cation and mapping of areally a ground instantaneous fi eld of view (GIFOV), exhibits a greater decrease in emissivity between extensive occurrences of other minerals, includ- or ground spatial resolution, of 90 m. Figures bands 13 and 14 than calcite. This characteristic ing carbonates, although the ASTER SWIR data 1 and 2 exhibit the spectral features of quartz, is caused by the greater width and shorter wave- are more sensitive at detecting hydrous quartz calcite, and dolomite in this spectral region at length position of the bending feature of dolo- (e.g., opal and chalcedony) and differentiating original laboratory resolution and convolved to mite at 11.15 µm relative to the bending feature carbonate mineral species. Despite its poten- ASTER sampling and bandpass (Table 1). The of calcite at 11.27 µm. tial utility, the mineral mapping capabilities of emissivity spectra shown in these fi gures were In the 8–11 µm spectral region measured by ASTER TIR data are often underutilized in sci- created by applying Kirchoff’s Law, E = 1 – R, ASTER, some fabricated construction materials entifi c studies. where E and R are emissivity and refl ectance, such as paving concrete and asphalt (macadam) This study evaluates the utility of band ratio to refl ectance spectra from a mid-infrared labo- have absorption features that are similar to that analysis techniques applied to ASTER thermal ratory spectral library (Salisbury et al., 1991). of quartz at ASTER sampling and bandpass infrared emissivity data for the identifi cation Kirchoff’s Law inverts refl ectance peaks into (ASTER Spectral Library, 2002), possibly due and mapping of quartz and carbonate minerals emissivity troughs commonly referred to as to quartz sand in the aggregate used to make across a 3.5º × 4.5º (389 km × 387 km) area of the central Great Basin in northern Nevada. The quartz and carbonate mineral maps were overlain with geologic maps of a wide range of scales (1:500,000–1:6000) to evaluate their reliability and to identify previously unknown occurrences of quartz and carbonate to guide future investigations. Of particular relevance to metallogeny was evidence of hydrothermal quartz, including jasperoids or other quartz associated with argillic and phyllic alteration, in areas of known mineralization. Also evaluated was the utility of the mineral maps for identifying quartz and/or carbonate anomalies within complex, deformed terranes for which only coarse-scale geologic mapping is available. Such anomalies can enhance understanding of these terranes by delineating stratigraphic marker horizons and structural features in need of more detailed geologic mapping.

METHODS

Quartz and carbonate minerals are spectrally characterized by strong vibrational absorption Figure 1. Plot of reference laboratory spectrum of quartz from Salisbury et al. (1991), con- features within the 8–14 µm atmospheric win- verted to qualitative emissivity using Kirchoff’s Law. The spectrum at original resolution is dow (Salisbury and D’Aria, 1992a; Hook et shown in blue. The spectrum convolved to ASTER (Advanced Spaceborne Thermal Emis- al., 1999) that is measured by the ﬁ ve thermal sion and Reﬂ ection Radiometer) spectral resolution (Table 1) is shown in red. ASTER band infrared bands of the ASTER sensor. Table 1 centers are also shown. Note quartz reststrahlen absorption features at bands 10 and 12.

Geosphere, February 2008 219

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra

are produced from Level 1B data using MOD- TRAN-based atmospheric correction and a temperature-emissivity separation (TES) algorithm developed by Gillespie et al. (1998, and references therein). The Level 1B data were processed from the original Level 1A format by the Earth Remote Sensing Data Analysis Center (ERSDAC) of Japan. A total of 108 ostensibly cloud-free scenes of ASTER emissivity data acquired between 1 May and 30 September 2000–2006 were obtained from EROS and resa- mpled to the geographic projection using a near- est-neighbor kernal based on satellite ephemeris data contained within the data ﬁ les. The May– September dates were chosen to avoid snow cover and assure highest possible solar elevation angles, thus maximizing solar illumination. Based on the TIR emissivity signatures of quartz and carbonate minerals shown in Figures 1 and 2, indices using compound band ratios were developed to identify these mineral groups.

Figure 2. Plot of reference laboratory spectra of calcite (blue) and dolomite (green) from Salisbury et al. (1991), converted to qualitative emissivity using Kirchoff’s Law. The spectra montmorillonite convolved to ASTER (Advanced Spaceborne Thermal Emission and Reﬂ ection Radiom-

eter) spectral resolution (Table 1) are shown in red. ASTER band centers are also shown. kaolinite Note carbonate bending mode absorption features at band 14.

gypsum these materials. Aggregates are often either bands 10 and 11, than do fi ner grain sizes. Dry quartz (or granite, which is dominated spectrally quartz-bearing soils show larger increases in by quartz) or limestone, or a mixture of the two. emissivity between ASTER bands 12 and 13 As concrete and macadam weather, the cement- than do moist soils. Mixtures of quartz with ing matrix becomes progressively less exposed, other minerals can also affect spectral shape. Emissivity (offset for clarity) and the aggregate more so. As a result, the TIR Figure 3 shows emissivity spectra of several emissivity signatures of concrete and macadam minerals common in rocks and soils that, if muscovite will become more similar with age (J. Salisbury, present in suffi cient amounts, can obscure the 2007, personal commun.). Quartz signatures presence of quartz or carbonate. The presence of ASTER Band Centers: 14 (and those of limestone) have been identifi ed these minerals in suffi cient concentrations will 10 11 12 13 elsewhere in asphalt road aggregate using the decrease the prominence of the diagnostic quartz 8.5 9.0 9.5 10.0 10.5 11.0 Spatially Enhanced Broadband Array Spectro- emissivity peak at band 11 or create an emis- Wavelength (μm) graph System (SEBASS), an airborne hyper- sivity absorption feature at those wavelengths. spectral thermal imaging system (Kirkland et The presence of montmorillonite, kaolinite, or Figure 3. Plot of laboratory spectra of mont- al., 2002). Many soils contain abundant quartz muscovite, among other minerals, will result morillonite, kaolinite, gypsum, and musco- (e.g., ultisols), and thus will also have TIR emis- in a substantial decrease in emissivity between vite from Salisbury et al. (1991), converted sivity signatures similar to that of quartz (Salis- bands 10 and 12. Minerals such as phyllosili- to qualitative emissivity using Kirchoff’s bury and D’Aria, 1992b). Therefore, surface cates (clays and micas), carbonate, and sulfates Law. These minerals commonly occur in features other than quartz-bearing rocks may be (including gypsum) can be accurately identifi ed rocks and soils and have spectral features in identifi ed as quartz using ASTER thermal data. using ASTER data of the SWIR spectral region the 8–14 µm atmospheric window measured Salisbury and D’Aria (1992b) described how (1.4–2.5 µm; Rowan et al., 2005; Rockwell et by ASTER (Advanced Spaceborne Ther- grain size, soil moisture, and mineral mixtures al., 2006). Therefore, ASTER SWIR data (30 mal Emission and Refl ection Radiometer) can have signifi cant effects on the shape of the m GIFOV) can be used to identify many rock- that can substantially affect TIR (thermal TIR emissivity spectra of rocks and soils. In forming minerals that will affect the TIR spec- infrared) spectral response. Where these quartz-bearing soils, coarse grain sizes show tral response. and other minerals occur in mixtures with much larger increases in emissivity between ASTER Level 2 surface emissivity data prod- quartz, the presence of quartz can be spec- ASTER bands 12 and 13, and between ASTER ucts (AST_05) from the EROS Data Center trally obscured, as discussed in text.

220 Geosphere, February 2008

Equation 1 is the index formula for quartz, and higher positional errors in the ephemeris data indices were overlain with 1:24,000 scale vector- equation 2 is the index formula for carbonate. than do scenes acquired with near-nadir geom- based geologic map data of the Alligator Ridge etries, requiring the use of the rubber-sheeting, and Bald Mountain gold districts in White Pine rather than polynomial, transformation. Rubber County (Nutt, 2000; Nutt and Hart, 2004). These Equation 1 (quartz index): sheeting is based on triangle-based fi nite ele- districts are known to contain large jasperoids [band 11/(band 10 + band 12)] ment analysis (Watson, 1992). Because of the of multiple ages, hydrothermal alteration, and (a) variable positional accuracies of the satellite a wide range of lithologies including abundant × (band 13/band 12) ephemeris data, the 90 m GIFOV of the ASTER carbonate rocks (Nutt and Hofstra, 2003, 2007). (b) thermal data that made control point selection Minimum DN value thresholds were chosen for diffi cult, and the nature of the rubber-sheeting each index at the level at which pixels began to Equation 2 (carbonate index): transformation, geometric distortions may be occur outside of geologic units known to con- band 13/band 14 locally present in the mineral index maps. Sev- tain the indexed mineral. To verify the accuracy eral small and isolated cumulus clouds were of the thresholds, ASTER emissivity spectra masked from the carbonate mineral index map. of surfaces with high index DN values (Fig. 4) This quartz index exploits the emissivity To determine the minimum DN levels corre- were extracted from the original data to deter- absorption features at ASTER bands 10 and 12 sponding to accurate detections of quartz or car- mine their similarity with the reference labora- relative to bands 11 and 13. Expression (a) of bonate by the mineral indices, the georeferenced tory spectra (Figs. 1 and 2). Figure 4 shows that the index will yield bright values for areas that are high in band 11 relative to the sum of bands 10 and 12, and expression (b) will yield bright values for areas that are high in band 13 relative to band 12. The quartz index is the product of Carbonates: these two expressions, both of which yield high values for quartz-bearing surfaces. The utility of limestone/dolomite, Guilmette Fm. (Dg) the type of compound band ratio used in expres- Simonson Dolomite (Dsi) sion (a), in inverted form, for isolating specifi c absorption features in imaging spectrometer data dolomites, undifferentiated (DSOd) was described by Crowley et al. (1989). A dif- limestone/dolomite, Guilmette Fm. (Dg) ferent quartz index that exploits the same spec- Eureka Quartzite (Oe) tral features as expression (a), and the carbonate jasperoid breccia with quartzite fragments, index of equation 2, was described by Ninomiya Quartz-bearing Chaotic unit (Tch), Water Canyon, Bald lithologies: Mountain district et al. (2005) for application to ASTER TIR radi- jasperoid in Joana Limestone (Mjj), Mooney ance-at-sensor data. High digital number (DN) Basin, Bald Mountain district values for these indices indicate spectral signa- jasperoid in Joana Limestone (Mj) near tures similar to those of the particular mineral contact with underlying Pilot Shale (MDp), group they were designed to map, and should southwest of Vantage deposit, Alligator Ridge district indicate the presence of quartz or carbonate if jasperoid in Guilmette Fm. (Dg), north of the ASTER spectral signatures are unambiguous Yankee deposit, Alligator Ridge district with those of other surface materials. Given the greater decrease of emissivity between bands 13 jasperoid in Pilot Shale (MDp), north of Yankee deposit, Alligator Ridge district

and 14 for dolomite relative to calcite, dolomitic ASTER Surface Emissivity (offset for clarity) rocks should exhibit higher carbonate index conglomerate with chert and quartzite clasts, values than limestone and other calcite-bearing with some limestone beds, Diamond Peak Fm. (Mdp): surfaces. The indices were applied to the 108 scenes of ASTER emissivity data on a scene-by- Long Valley, east of Vantage deposit, scene basis using automated batch processing. Alligator Ridge district The resultant mineral index maps were then along eastern front of Alligator Ridge, histogram matched and mosaicked into single Long Valley coverages, which were then georeferenced ASTER Band Centers: to the Universal Transverse Mercator (UTM) 10 11 12 13 14 projection using a rubber-sheeting transformation and control points from an orthocorrected Wavelength (μm) coverage of Landsat Thematic Mapper (TM) imagery acquired from the U.S. Geological Sur- vey Seamless Data Distribution system. Control Figure 4. Plot of ASTER (Advanced Spaceborne Thermal Emission and Refl ection Radiom- points from vector geology coverages (Luding- eter) emissivity spectra of surfaces in the Alligator Ridge–Bald Mountain area identifi ed as ton et al., 2005; Crafford, 2007) were used in containing either quartz or carbonate using ratio-based indices. Spectra of carbonate-bear- some areas where more detailed control was ing lithologies are shown at top. Jasperoids formed by hydrothermal processes are indicated required. ASTER scenes acquired with signifi - in red at right. ASTER band centers are also shown. Note correspondence of spectral shapes cantly off-nadir viewing geometries (>~6º) have with the reference spectra shown in Figures 1 and 2.

Geosphere, February 2008 221

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra

the mid-infrared spectral features of quartz and ence laboratory spectra. Index pixels with DN or intimate mixtures with other minerals or carbonate are present in the selected spectra, and values below the detection thresholds were set materials. that there is little consistent variation in spectral to zero, and color tables were applied to index shape between quartz-bearing units of sedimen- pixels above the thresholds. Pixels with the RESULTS AND DISCUSSION tary and hydrothermal origin (e.g., jasperoids). highest index values for quartz and carbonate The populations of index pixels selected as were set to brightest red and green, respectively. General Characteristics of Mineral Index accurate mineral detections showed strong spa- Successively darker shades of these colors were Maps tial contiguity with each other. Spatial contigu- assigned to pixels with decreasing DN values. ity thus served as a secondary, qualitative means The gradational color tables enable the interpre- Figure 6 shows an overview of the quartz and of choosing index detection thresholds. ASTER tation of the index level for each pixel selected carbonate mineral index maps generated from emissivity spectra of sand dunes and hot springs as a mineral detection. The index values of a the ASTER thermal infrared data. The index that were identifi ed as either quartz or carbonate pixel are affected by abundance of that particu- maps are provided here in GeoTIFF raster for- bearing elsewhere in the study area were also lar mineral or mineral group, degree of exposure mat (quartz map, carbonate map).1 Although the extracted to determine if the thresholds were relative to soil and vegetation cover, carbonate results show general consistency across the study accurate across the entire study area (Fig. 5). mineral type (e.g., calcite or dolomite), grain area, noise and inter-scene variations in index Such spectra also corresponded well with refer- size distribution, moisture content, and/or areal levels are locally present. The carbonate index map is subject to both random speckle noise and striping in the across-track (west-northwest– east-southeast) direction, as expected using a density-sliced ratio of two spectral bands. The speckle effects are caused by low signal-to- Carbonates: noise levels of the data enhanced by the ratioing travertine terrace, Potts Ranch process, and the striping is caused by interdetec- hot springs, Monitor Valley, Lander County tor performance variation within the 10 detec- travertine terrace, Diana's Punchbowl tor arrays for each TIR band in the whiskbroom hot springs, Monitor Valley, Lander County scanning system. The index maps contain some thick quartz sand dune, Newark Valley, sharp breaks in index values across boundaries Quartz-bearing Alligator Ridge district of scenes acquired on different dates, especially features: sand dunes with quartz and clay in the northwest quadrant of the area near long minerals (montmorillonite?) ± gypsum, 117ºW. These breaks occur most often along Winnemucca Dunes, Silver scene boundaries oriented in the along-track State Valley, Humboldt County (north-northeast–south-southwest) direction. The breaks are most likely caused by subtle, uncorrected atmospheric and/or soil moisture variation between adjacent scenes, possibly exacerbated by potential errors in the automated histogram matching process used to create the silica sinter, The Geysers, mosaic of mineral index maps. Inter-scene vari- Beowawe hot springs, Whirlwind ability related to the ASTER instrument, solar Valley, Lander and Eureka Counties ASTER Surface Emissivity (offset for clarity) irradiance, and/or atmospheric and surface scat- silica sinter, Beowawe hot springs, tering effects was described by Hewson et al. Crescent Valley, Eureka County (2005) as related to diffi culties in generating seamless geological maps from data acquired on different overpass dates. Plate 1 shows the mineral index maps in vector format overlain on a background of Landsat ASTER Band Centers: TM data. The index maps were simplifi ed prior 10 11 12 13 14 to vectorization using a 3 × 3 majority fi lter. The locations of important ore deposits are indicated Wavelength (μm) by deposit type and commodity. Hot springs are also shown. This map enables interpretation Figure 5. Plot of ASTER (Advanced Spaceborne Thermal Emission and Refl ection Radi- of surface characteristics in areas identifi ed as ometer) emissivity spectra of geomorphic and hot springs features identifi ed as containing either quartz or carbonate using the ratio-based indices. Spectra of carbonate-bearing travertine terraces are shown at top. Hot springs features formed by hydrothermal processes 1If you are viewing the PDF of this paper or read- are indicated in red at right. ASTER band centers are also shown. Note correspondence ing it offl ine, please visit http://dx.doi.org/10.1130/ of spectral shapes with reference spectra shown in Figures 1 and 2. The spectrum of the GES00126.S4 and http://dx.doi.org/10.1130/ Winnemucca Dunes was identifi ed as quartz bearing based mainly on the sharp increase in GES00126.S5 or the full-text article on www. gsajournals.org to access the quartz (00126_sf01.tif) emissivity between ASTER bands 12 and 13. The shape of the spectrum from bands 10–13 and carbonate (00126_sf02.tif) index maps in Geo- shows infl uence of a mixture with other minerals, possibly gypsum and muscovite. TIFF fi le format (for use in GIS systems).

222 Geosphere, February 2008

Figure 6. Overview of quartz and carbonate mineral index maps. Areas shown in detail in subsequent fi gures are indicated by white rectangles. A—Wood Hills and northeastern East Humboldt Range. B—Ruby Mountains and East Humboldt Range. C—Kinsley mining district. D—Winnemucca Dunes. E—Easy Junior mining district. F—Independence Mountains. G—Beowawe hot springs. H—hot springs, Ruby Valley. I—Diana’s Punchbowl hot springs, Monitor Valley. J—Illipah mine area. K—Paradise Peak mine area. L—Coffi n Mountain area, southern Piñon Range. M—Bald Mountain and Alligator Ridge mining districts. Major mineral trends, other districts, and mines are indicated in yellow. IN: Independence Trend. GT—Getchell Trend. CN—Carlin Trend. BM/EK—Battle Mountain–Eureka Trend. JB—Jarbidge district. RH—Rawhide district. RO—Robinson district. CP—Colado/Perlite diatomite mine. FC—Florida Canyon mine. LT—Lone Tree mine. MG—Marigold mine. MD—McDermitt deposit, Cordero mine. RM—Round Mountain mine. PC—Palisade Canyon perlite prospect. PP—Pamela Placer perlite prospect. Other features mentioned in the text are shown in cyan. DM—Diamond Mountains. GQ—quartz anomaly near Gold Quarry mine, Carlin Trend. QS—quartz-bearing soils. BV—carbonate soils in Buena Vista Valley. CS— carbonate soils in Carson Sink. Counties are indicated on index map of Nevada at lower left. H—Humboldt County. P—Pershing County. C—Churchill County. M—Mineral County. L—Lander County. K—Eureka County. E—Elko County. W—White Pine County. N—Nye County. Mineral index maps in GeoTIFF: quartz map, carbonate map (see footnote 1). To access a full-resolution PDF of this fi gure, please visit http://dx.doi.org/10.1130/GES00126.S6 or the full-text article on www.gsajournals.org.

Geosphere, February 2008 223

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra . The mineral index . gures. The Landsat image is gures. ine, please visit http://dx.doi. U.S. Geological Survey Seamless Data Distri- (see legend). Displayed ore deposit locations were deposit locations were (see legend). Displayed ore , commodity, and deposit information. The deposits and deposit information. , commodity, is paper or reading it offl reading or is paper displayed in hues of blue. Hot spring locations are from from displayed in hues of blue. Hot spring locations are le of Plate 1. ned by Long et al. (2000), or listed in Wallace et al. (2004), as well the largest known examples of Wallace listed in ned by Long et al. (2000), or ltered maps are shown in raster format in Plates 2 and 3, and in other fi format in Plates 2 and 3, other shown in raster maps are ltered lter. Unfi lter. cant ore deposits (colored symbols), and major roads (gray lines). Quartz detected using the ASTER (Advanced Spaceborne (gray lines). Quartz detected using the roads symbols), and major deposits (colored cant ore cant Au, Ag, Cu, Pb and Zn deposits as defi Au, cant ection Radiometer) TIR (thermal infrared) data is shown with red polygons, and detected carbonate minerals with green polygons polygons, and detected carbonate minerals with green data is shown with red TIR (thermal infrared) ection Radiometer) ed prior to vectorization using a 3 × majority fi ed prior Plate 1. Map of study area showing vectorized quartz and carbonate index maps, overlain on Landsat Thematic Mapper derived from Thematic Mapper showing vectorized quartz and carbonate index maps, overlain on Landsat Plate 1. Map of study area to hot springs (black Xs), signifi bution system, relative Thermal Emission and Refl shown are the economically signifi shown are fi to access the full-resolution the full-text article on www.gsajournals.org or org/10.1130/GES00126.S1 Shevenell and Garside (2005). The ore deposit symbols indicate deposit type, whereas the color indicates the primary commodity the color deposit symbols indicate type, whereas The ore Shevenell and Garside (2005). geologic with related Data System (2007), an international database of mineral site records the Mineral Resources selected from of th viewing the PDF Sb, Hg, and barite deposits (Lowe, 1985; Sherlock et al., 1996). If you are Sn, Be, F, W, the Fe, Mn, Mo, a color composite of bands 2, 3, and 4 displayed in red, green, and blue, respectively. In this treatment, green vegetation is green In this treatment, and blue, respectively. green, composite of bands 2, 3, and 4 displayed in red, a color maps were simplifi maps were

224 Geosphere, February 2008

either quartz or carbonate. Many large areas dis- with both limestone (colored blue) and dolo- The more detailed scale of the Crafford turbed by active mining have high quartz index mite (colored cyan) units, with the highest (2007) geology coverage permits fi ner inter- values (Fig. 6), especially along the Carlin Trend index values most often corresponding with pretation of the remote sensing results. Excel- (CN), the Independence Trend (IN), the Twin dolomitic units, as expected given the greater lent correlation of the mineral index maps with Creeks mine at the northeast end of the Getchell decrease in emissivity between ASTER bands units known to contain quartz or carbonate is Trend (GT), the Lone Tree (LT) and Marigold 13 and 14 for dolomite (Fig. 2). Many of the shown in Tables 2 and 3. For example, Figure 7 (MG) mines along the Battle Mountain–Eureka mapped quartz and carbonate anomalies are exhibits the accurate mapping of quartz within Trend (BM/EK), the Florida Canyon (FC) also located within units described as primar- units of quartzite (metamorphosed Ordovician gold mine in Humboldt County, and the Rob- ily shale or felsic volcanic rocks. Most, but not Eureka Quartzite, Ocqm) in the Wood Hills inson copper district (RO) near Ruth and Ely. all, of these anomalous occurrences of quartz of Elko County, and foliated metaquartzite Tailings deposits and heap leach piles at many and carbonate refl ect the coarse scale and gen- (in part Precambrian to Cambrian Prospect mines show high quartz index values. Generally, eralized descriptions of the primary lithologies Mountain Quartzite, _Zqm) in the nearby East quartz is very abundant in these areas, given the of the geologic units in the statewide geology Humboldt Range. Figure 7 also shows how quartz-rich nature of the ore-bearing rocks. In coverage. Units described as primarily chert, carbonate was detected within lower Paleo- contrast, along most of the Battle Mountain– especially within the Roberts Mountain alloch- zoic calcite marbles (O_cm), dolomite and Eureka Trend southeast of the Marigold mine, thon, contain units of quartzite, chert, and shale, graphitic marbles (DOcm), the Ely Springs and at Round Mountain (RM, Fig. 6), the prin- and the mapped quartz most often corresponds Dolomite and Hanson Creek Formation (SOc), cipal mines are characterized by only localized to the quartzite units within these complex ter- and limestones of the Devils Gate and Guil- areas of quartz and carbonate. Vegetation cover ranes. The quartz-rich Diamond Peak Forma- mette Formations (Dc). Note how the highest (shown in shades of blue) within areas identifi ed tion has been grouped with associated shale carbonate index values and most complete as quartz or carbonate ranges from none to mod- units in the statewide geology coverage (e.g., coverage of mapped carbonate pixels spatially erate density. Abundant vegetation and/or poor along the west fl ank of the Diamond Mountains correspond with dolomitic rocks. This effect is exposure commonly preclude remote mineral mentioned above). Several occurrences of iden- partly due to better exposure of the dolomitic detection. For example, patchy occurrences of tifi ed carbonate within units described as felsic units caused by lower densities of vegetation quartz were identifi ed along the western fl anks volcanic rocks also refl ect the broad nature of cover than present on calcite-bearing rocks of the Diamond Mountains (DM, Fig. 6) in east- the described primary lithologies. For example, (Plate 1), and its spectral response relative to ern Eureka County within the Upper Mississip- within the Sand Springs Range in Churchill and calcite described above. pian Diamond Peak Formation, a conglomerate Mineral Counties east and north of the Rawhide The utility of the ASTER-derived mineral with clasts of chert and quartzite that consis- Ag district (RH, Fig. 6), mapped carbonate cor- index maps for guiding future detailed geo- tently shows strong quartz index values across responds to shelf limestones intercalated with logic mapping in complex and/or undifferen- the eastern half of the study area. Quartz was volcaniclastic rocks. The mineral maps demon- tiated terranes is illustrated in Figures 8 and identifi ed principally on south-facing slopes strate both the merits and problems inherent in 9. Figure 8 shows how the detail of geologic of east-striking drainage divides in this area. such small-scale lithologic maps with hetero- mapping in Ruby Mountains (Coats, 1987) is South-facing slopes typically have signifi cantly geneous units. Hence, lithostratigraphic (rather signifi cantly greater than in the East Humboldt less vegetation cover than north-facing slopes than chronostratigraphic) geologic maps of Range to the northeast. The Ruby Mountains in the Northern Hemisphere due to increased the largest possible scale should be used when are underlain by late Precambrian to early annual solar illumination. interpreting mineralogic information derived Paleozoic metasedimentary rocks, mainly Based on typical compositions of the litholo- from remote sensing data. calcite marbles (O_cm) and metaquartzites gies and features identifi ed with the ASTER (_Zqm). In contrast, the East Humboldt Range TIR data, we estimate that the minimum detec- Map of Mineral Indices Overlain on is underlain by an undifferentiated metamor- tion limits of mineral abundance for the ratio- 1:250,000 Scale Geology phic unit (TAgn) consisting of gneiss, schist, based methodology presented here is ~70% of and migmatite of a wide range of ages from bulk composition for quartz and 85%–90% for Plate 3 shows the mineral index maps over- Archean to Oligocene. Quartzite and quartzitic carbonate. lain with 1:250,000 scale geology from Craf- schists within this unit are delineated by the ford (2007) derived from county geologic maps quartz index map, as are the metaquartzites in Map of Mineral Indices Overlain on of the same scale. Polygon outlines of geologic the Ruby Mountains. Carbonate minerals were 1:500,000 Scale Geology units have been color coded to refl ect lithologies detected in only a small portion of the calcite relevant for interpreting the mineral index maps. marble in the Ruby Mountains. These areas, Plate 2 shows the mineral index maps in the This color coding was based upon descriptions some of which had high carbonate index val- context of the statewide geology of Luding- of the regional geologic units developed by ues in discrete patches, could correspond with ton et al. (2005). Color coding of the geologic Crafford (2007), and other information from either very thick bedded, well exposed, or more units is based on the primary lithology attribute the county maps. The color coding should only dolomitic sections of the marble unit. of the vector geology coverage, and second- be used as an approximate guide to lithology, The geology of the Independence Mountains ary lithologies from the coverage are listed in particularly for the coding related to units con- (F, Fig. 6) is shown in Figures 9 and 10. The the explanation in parentheses. Quartz identi- taining quartzites and/or conglomerates with Ordovician McAfee Quartzite and Cambrian fi ed using the ASTER data corresponds well quartzite clasts (colored magenta). Although Prospect Mountain Quartzite are highlighted by with units described as primarily quartzite units composed primarily of chert have been the quartz mineral index map (Fig. 9). Within (colored gold) and chert (colored black), and color coded in purple, minor chert units may the Independence Mountains, the McAfee in alluvium and/or colluvium derived from also be contained within the quartzite and/or Quartzite is part of a complex, undifferentiated them. Identifi ed carbonate corresponds well conglomerate grouping. lower Paleozoic unit (D_s) consisting of shale,

Geosphere, February 2008 225

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra le of Plate olution fi create the shaded-relief image (Reheis, 1999). the shaded-relief create from Ludington et al. (2005) and a shaded-relief Ludington et al. (2005) and a shaded-relief from om the elevation model is visible. The explanation om the elevation model is visible. es. Main roads are shown in white. If you are viewing shown in white. If you are are es. Main roads ection Radiometer. ection ine, please visit http://dx.doi.org/10.1130/GES00126.S2 or the full-text article on www.gsajournals.org to access the full-res the full-text article on www.gsajournals.org or ine, please visit http://dx.doi.org/10.1130/GES00126.S2 2. ASTER—Advanced Spaceborne Thermal Emission and Refl ASTER—Advanced Spaceborne 2. the PDF of this paper or reading it offl reading or of this paper the PDF Plate 2. Map of study area showing quartz and carbonate index maps overlain on background of 1:500,000-scale geology and faults showing quartz and carbonate index maps overlain on background Plate 2. Map of study area used to second DEM data were U.S. Geological Survey DTED-1 3-arc digital elevation model (DEM) having 90 m spatial resolution. so that topography fr partially transparent The geology polygons are carbonate minerals in green. Detected quartz is shown red, also shown, in parenthes geology coverage. Secondary lithologies are the vector at right indicates the primary lithologies from

226 Geosphere, February 2008

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Remote identifi cation of quartz and carbonate minerals, Nevada ine, please visit ord (2007) and a shaded-relief digital elevation ord (2007) and a shaded-relief ies or geologic features (see explanation of color (see explanation of color geologic features ies or he PDF of this paper or reading it offl reading or of this paper he PDF he geology coverage and county-level maps should be le of Plate 3. ASTER—Advanced Spaceborne Thermal Emission ASTER—Advanced Spaceborne le of Plate 3. ection Radiometer. ection http://dx.doi.org/10.1130/GES00126.S3 or the full-text article on www.gsajournals.org to access the full-resolution fi to access the full-resolution the full-text article on www.gsajournals.org or http://dx.doi.org/10.1130/GES00126.S3 and Refl Plate 3. Map of study area showing quartz and carbonate index maps overlain on background of 1:250,000-scale geology from Craff of 1:250,000-scale geology from showing quartz and carbonate index maps overlain on background Plate 3. Map of study area to included quartz-and carbonate-bearing litholog coded relative model (Reheis, 1999). Geology polygon outlines have been color and t guide to included lithology, is included only as an approximate coding shown here The polygon color coding at top right). viewing t shown in white. If you are are consulted to obtain detailed and accurate information about geologic units. Main roads

Geosphere, February 2008 227

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra (continued) uartz arenite locations where known Primary quartz-bearing lithologies, rich alluvium derived from conglomerates of Diamond Peak Formation Quartzite Cherts and siliciclastics Quartzite and/or chert Conglomerate (?) Sandstone, other clastics Quartzite or sandstone Chert/argillite, conglomerate (?) from Crafford (2007) Geologic formation names and descriptions Shale, siltstone, sandstone, and minor carbonate — greenstone terrigenous clastic and minor carbonate rocks dolomite clastic rocks and limestone conglomerate Mcl—Shale, si ltstone, sandstone, and conglomerate Conglomerate with quartzite and chert clasts (Mdp) Zq—Cross-bedded quartzite, siltstone, and phyllite Quartzite c—Dolomite, limestone, and shale Minor quartzite beds (?) c—Limestone, dolomite, shale, sandstone, and D s—Shale, chert, quartzite, greenstone, and limestone Quartzite and chert GC—Golconda terrane: basinal, volcanogenic, QThs—Hot spring travertine, sinter, and tufa Zqs—Quartzite, siltstone, conglomerate, limestone, and Hot spring sinter terraces MDcl—Siltstone, limestone, shale, and sandstone Jasperoid (where Diamond Peak Formation is absent) DSt—Platy limestone, dolomite, and chert Js Chert and jasperoid Ts3—Tuffaceous sedimentary rocks local diatomite Possible or other hydrous quartz; quartz- JO—Jungo terrane: turbiditic fine-grained terrigenous MDst—Shale, graywacke, siltstone, chert, conglomerate, TABLE 2. SELECTED GEOLOGIC UNITS WITH SIGNIFICANT QUARTZ DETECTED WITH ASTER (ADVANCED SPACEBORNE THERMAL EMISSION AND REFLECTION RADIOMETER) DATA (volcanics), Sonoma Range, Humboldt County Canyon Formation (PPh), Schoonover Sequence (PPMs), Elko County Shale (MDp), Diamond Peak Formation (Mdp) Shale (MDp) within Hanson Creek Formation (SOh, SOhc), Independence Range; jasperoid in Maggie Creek Canyon north of Gold Quarry deposit, Eureka County Nye County; Ts in Pershing County Monitor Range, northern Nye County; Argillite of Lee Canyon (Ma), Elko County Mountain Quartzite, and equivalents; Gold Hill Formation (CZgh), northern Nye County Counties phyllite, slate, and fine-grained quartzite (J u), Humboldt County; s, JCounty; s, Stillwater Range, Churchill si, sl, Clan Alpine Mountains, Churchill County; qm, Pvs Valmy Formation (Ov); McAfee Quartzite (Om); Trd Havallah Formation, Pumpernickel Formation, Farrel Formation(s) from county and/or state geologic maps, locations Prospect Mountain Quartzite ( Pq), in part Zqm—Metaquartzite Foliated metaquartzite Prospect Mountain Quartzite ( Pq or pm), Osgood Chainman Shale (Mch), Joana Limestone (Mj), Pilot Carlin sequence (PPPcs), Elko County Chainman Shale (Mch, Mc), Joana Limestone (Mj), Pilot Pc—Cherty limestone, dolomite, shale, and sandstone Chert Vinini Formation (Ov) Roberts Mountain Formation (DSrm, Sr, St): jasperoid DOts—Calcareous shale, siltstone, chert, quartzite, and Sedimentary strata and interbedded tuffs (Tts), northern Ts3 or Qs in Elko and White Pine Counties, respectively; Slaven Chert (Ds), Lander County; PMh on state map, Osobb Formation ( o), Lander, Churchill, and Pershing Ja (Jgb onJa (Jgb state map), Stillwater Range, Churchill County Jcg—Conglomerate, limestone, and quartz sandstone Quartz sandstone, q Undivided volcanic and sedimentary rocks ( Pu) and

228 Geosphere, February 2008

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Remote identiﬁ cation of quartz and carbonate minerals, Nevada (?) (?) locations where known Primary quartz-bearing lithologies, with argillic and/or phyllic alteration in high Jarbidge Mountains southeast of Jarbidge epithermal Au/Ag district; perlite near Palisade Canyon prospect, Eureka County alteration in Paradise Peak mine area; perlite tuff near Pamela Placer prospect, Nye County chert-bearing rocks Jasperoid Conglomerate with quartzite clasts (?) Sandstone (?), conglomerate Conglomerate with quartzite clasts (continued) from Crafford (2007) TABLE 2. Geologic formation names and descriptions carbonate and volcanogenic rocks and landslide megabreccia siltstone, limestone, and carbonaceous limestone limestone Tr3—Rhyolitic flows and shallow intrusive rocks Silicic (locally glassy or perlitic) rhyolite, in part associated O td—Shale, chert, phyllite, quartzite, and limestone Quartzite Qs—Sand dunes Quartz sand dunes, Churchill County Dc—Limestone and minor dolomite Ocqm—Metaquartzite Metaquartzite O c—Limestone, dolomite, and quartzite Jasperoid (?) Quartzite, sandstone (?) P acl—Antler Sequence conglomerate, sandstone, and QToa—Older alluvium and alluvial fans Coarse-grained alluvium derived from quartzite- and Dcd—Dolomite, sandstone, and limestone TAgn—Gneiss, schist, and migmatite Sandstone containing variable amounts of dolomite Quartzite and possibly quartzitic schist units Tt2—Silicic ash-flow tuff Pacl—Antler Sequence sandstone, conglomerate, Silicic welded tuff, magmatic hydrothermal quartz-alunite Kcg—Siltstone, shale, conglomerate, and limestone Conglomerate with quartzite clasts County; rhyolitic and dacitic volcanic rocks ( D), Humboldt County; undivided volcanic rocks (Tvu), Eureka County and Manhattan mine areas, northern Nye County Counties, respectively beds/lenses in Pogonip Group, Big Bald Mountain, Bald Mountain district, White Pine County Formation, Coffin Mountain area, southern Piñon Range, Elko County Range, Elko County Mineral County; Tvu, Paradise Peak mine area, Northern Nye County; Monotony Tuff and Lava (Tm), northern Nye County Mountain Formation (Pem) and Park City group (Ppc), Elko County (PPPu, P a), Humboldt County; undivided only small and local quartz occurrences in Elko Eureka Counties sedimentary rocks (Mu?, P a), Eureka County Pluvial lake deposits (Qp), Elko and Churchill Counties Big Island Formation (Tbi), Elko County Qpl—Playas, lake beds, and flood plains Jarbidge Rhyolite (Tjr) in high Mountains, Elko Tbg—Basalt, gravel, and tuffaceous sedimentary rocks Quartz beach sand Quartz gravels and/or silicic tuff Shale, limestone, and quartzite (OCsl), Round Mountain Alluvial fan deposits (Qf or Qa), Lander and northern Nye Eureka Quartzite (Oe) Locally includes Eureka Quartzite (Oe); sandstone Ocq—Quartzite Dunlap Formation (Jd), Mineral County WPL—Pamlico-Lodi assemblage, Walker Lake terrane: Quartzite Oxyoke Canyon Sandstone Member (Dno) of Nevada Undifferentiated metamorphic rocks, East Humboldt Lake deposits (Qlg), Pershing County Qpl—Playa, lake bed, and flood plain deposits Lake deposits and related sand dunes Younger alluvium (Qya), Humboldt County Qya—Younger alluvium Quartz sand dunes Rib Hill Sandstone (Pr), White Pine County Intermediate volcanics: rhyodacite, andesite, tuff (Tvi), Psc—Siltstone, sandstone, limestone, and dolomite Garden Valley Formation (Pg), Eureka County; Edna Sandstone Battle Formation or Mountain Conglomerate Includes jasperoid breccia (Tj) in White Pine County br—Mixed breccias including volcanic, thrust, jasperoid, Formation(s) from county and/or state geologic maps, locations Newark Canyon Formation (Knc or Kn), Ks on state map;

Geosphere, February 2008 229

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra locations where known Primary carbonate-bearing lithologies, County response) County Limestone and dolomite Limestone Limestone and dolomite Limestones intercalated with felsic volcanic rocks, Mineral Limestone and dolomite, Pershing County Limestone and dolomite from Crafford (2007) Geologic formation names and descriptions carbonate and volcanogenic rocks limestone shale and carbonate turbidites conglomerate c—Dolomite, limestone, and shale Limestone and dolomite c—Limestone, dolomite, shale, sandstone, and Dc—Limestone and minor dolomite Limestone and dolomite DSc—Dolomite Dolomite Dcd—Dolomite, sandstone, and limestone Dolomite and local limestone P acl—Antler Sequence conglomerate, sandstone, and MDcl—Siltstone, limestone, shale, and sandstone Limestone Qpl—Playas, lake beds, and flood plainsTt1—Silicic ash-flow tuffs Tt3—Silicic ash-flow tuffs Carbonate salts, probably calcite Unknown, possibly speckle noise Unknown, possibly speckle noise SOc—Dolomite, limestone, and shale P Dolomite and limestone c—Limestone, dolomite, siltstone, sandstone, and ) TABLE 3. SELECTED GEOLOGIC UNITS WITH SIGNIFICANT CARBONATE DETECTED WITH ASTER (ADVANCED SPACEBORNE THERMAL EMISSION AND REFLECTION RADIOMETER) DATA northern Nye County w), Formation (Dg, Dgd), Nevada (Dn, Sod (DSd), northern Nye County ( np) (Dn) Dolomite, Geddes Limestone rocks, Elko County Shale (MDp); limestone and shale (MDu), northern Nye County County; PPPu, PCounty; PPPu, a, Humboldt County); Wildcat Peak Formation (P rocks (Tts), Elko County (SOh, SOhc), dolomitic rocks (Dc, DOd) Riepe Spring (P ) and Ely (PPine County e) Limestones, White County; younger alluvium (Qya), northeastern Carson Sink, Churchill County Devil’s Gate Limestone (Dd, Dg, Dgd), Guilmette Formation(s) from county and/or state geologic maps, locations Laketown Dolomite (Sl, DSOd); dolomite, undivided Prida Formation ( pu, p), Natchez Pass Formation Grouped with Ely Springs Dolomite (Oc) in Nye County Includes Pogonip Group (Op, O pw) Ocq—Quartzite Simonson and Sevy Dolomites (Ds), Nevada Formation O c—Limestone, dolomite, and quartzite Limestone and dolomite Dolomite Arcturus Formation (Par), White Pine County Windfall Formation, Eldorado Dolomite, Hamburg Excelsior Formation ( Psc—Siltstone, sandstone, limestone, and dolomite e) Limestone and dolomite Dun Glen Formation ( dg)Pluvial lake deposits (Qlg), Buena Vista Valley, Pershing SAS—Sand Springs terrane: basinal volcanogenic rocks J s—Shale, siltstone, sandstone, and minor carbonate Phenorhyolitic to phenodacitic ignimbrite and sedimentary Chainman Shale (Mch), Joana Limestone (Mj), Pilot Antler Peak and Highway Limestones (PPPa, Lander Luning Formation ( l), northern Nye County; ld WPL—Pamlico-Lodi assemblage, Walker Lake terrane: Ignimbrite, tuff, and interstratified tuffaceous sedimentary DOm O m DOcm—Dolomite and graphitic marble O cm—Calcite marble Dolomite marble, Woods hills, Elko County Calcite marble, Ruby Mountains and Wood Hills, Elko Ely Springs Dolomite (Oc), Hanson Creek Formation Robert Mountain Formation (DSrm) Park City Group (Ppc), Elko County Ely Limestone (P e)Undivided limy rocks (PPPu), Elko County; undivided DSt—Platy limestone, dolomite, and chert Pc—Cherty limestone, dolomite, shale, and sandstone Limestone and dolomite Limestone and dolomite (relatively weak carbonate Mbc—Bioclastic limestone Limestone, Elko County

230 Geosphere, February 2008

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Remote identifi cation of quartz and carbonate minerals, Nevada (A, Fig. 6). Quartzites indicated in magenta, f the maps. Map at left is from Coats (1987). ASTER— Coats (1987). f the maps. Map at left is from gure, please visit http://dx.doi.org/10.1130/GES00126.S7 or the full-text or please visit http://dx.doi.org/10.1130/GES00126.S7 gure, ection Radiometer. To access a full-resolution PDF of this fi PDF access a full-resolution To ection Radiometer. Figure 7. Subset of Plate 3 showing mineral mapping results in the Wood Hills and northeastern East Humboldt Range, Elko County Wood in the 7. Subset of Plate 3 showing mineral mapping results Figure the top o unit explanations. Interstate 80 extends across 1 and 2 for Tables to text and carbonate-bearing units in blue. Refer Advanced Spaceborne Thermal Emission and Refl Advanced Spaceborne article on www.gsajournals.org.

Geosphere, February 2008 231

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra ection Radiometer. To access a To ection Radiometer. ission and Refl . 6). Quartzite and quartzitic schist units can ed carbonate within calcite marble in Ruby Mountains. gure, please visit http://dx.doi.org/10.1130/GES00126.S8 or the full-text article on www.gsajournals.org. or please visit http://dx.doi.org/10.1130/GES00126.S8 gure, Figure 8. Subset of Plate 3 showing variation in geologic mapping detail between Ruby Mountains and East Humboldt Range (B, Fig Figure metamorphic units using the quartz mineral index map. Note small patches of identifi be delineated within undifferentiated of this fi PDF full-resolution Interstate 80 extends across the upper left of the maps. Map at left is from Coats (1987). ASTER—Advanced Spaceborne Thermal Em ASTER—Advanced Spaceborne Coats (1987). left of the maps. Map at is from the upper Interstate 80 extends across

232 Geosphere, February 2008

chert, quartzite, greenstone, and limestone that composes the Roberts Mountain allochthon of the Mississippian Antler orogeny in this area. The D_s unit is part of the Basin assemblage of Crafford (2007). Similarly, within the undifferentiated, allochthonous Golconda terrane (GC) of Crafford (2007) located in the northwestern Independence Mountains, the quartz mineral index map differentiated units of chert and/or argillite within the Devonian–Permian Schoonover Sequence. Occurrences of quartz in this area parallel the southwest-northeast strike of numerous thrust faults formed during the Permian–Triassic Sonoma orogeny (Miller et al., 1984). An anomalous occurrence of quartz was identifi ed in the vicinity of Coffi n Mountain in the southern Piñon Range in Elko County (40°16′02′′N, 116º00′19′′W; L, Fig. 6; Table 2). The anomaly consists of two lobes that together are >6 km long from north to south, and as much as 3 km wide. On the 1:250,000 scale map of Crafford (2007), the area is underlain by unit Dcd, consisting of dolomite, sandstone, and limestone, and the county-level data for the area lists Sevy, Simonson, and Nevada Formations, all Devonian units of primarily dolomitic composition. Inspection of a 1:62,500 scale map of the area (Smith and Ketner, 1978) revealed that the mapped quartz corresponds to the Oxyoke Canyon Sandstone Member of the Nevada Formation, the only sandstone in the autochthonous Devonian Carbonate Shelf sequence of Crafford (2007). Although the bulk of the mountain is underlain by the Beacon Peak Dolomite Member (Dnb) of the Nevada Formation, the Oxyoke sandstone forms the mountain summit and also occurs in a crude ring 1–2 km away from the summit to the north, east, and south. Quartz-bearing colluvium and/or fl oat derived from the Oxy- oke sandstone at the summit of the mountain conceal exposures of Beacon Peak Dolomite on sections of the western and eastern mountain fl anks. Signifi cant carbonate was detected Figure 9. Subset of Plate 3 over the Independence Mountains, Elko County (F, Fig. 6). within the Upper dolomite member (Dnu) of The quartz index map highlights the McAfee Quartzite within the undifferentiated unit the Nevada Formation ~1.6 km southwest of D_s of Crafford (2007) that composes the Roberts Mountain allochthon (Mississippian the summit of Coffi n Mountain, and within the Antler orogeny) in this area. Small outcrops of cherts and jasperoids were also identifi ed as Beacon Peak Dolomite, which is well exposed quartz bearing within this allochthon. The mapped jasperoid is shown in Figure 10. Units 1.5 km south of the summit. High quartz index of chert and/or argillite within the Devonian–Permian Schoonover Sequence (part of the values correspond to thick, ridge-forming undifferentiated Golconda terrane, GC, of Crafford, 2007) in the northwestern mountains exposures of the Oxyoke sandstone, and lesser were also mapped as quartz bearing. Exposures of identifi ed quartz in the Golconda ter- index values correspond to colluvium and fl oat rane parallel the general southwest-northeast strike of the many faults in this area (Miller derived from them. This example demonstrates et al., 1984) that were created during thrusting of the Golconda allochthon during the how large-scale lithostratigraphic maps are Permian–Triassic Sonoma orogeny. JC—Jerritt Canyon mine. CM—California Mountain required to accurately interpret the results of mine. ED—East Dash mine. SV—Saval mine. BW—Burns West mine. ASTER—Advanced the ASTER thermal infrared mineral mapping, Spaceborne Thermal Emission and Refl ection Radiometer. To access a full-resolution PDF and, conversely, how the mineral index maps of this fi gure, please visit http://dx.doi.org/10.1130/GES00126.S9 or the full-text article on can serve as a cost-effective means of both www.gsajournals.org. guiding and verifying geologic fi eld mapping.

Geosphere, February 2008 233

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra

Figure 10. Google Earth™ image of the large jasperoid (yellow arrow) in the Jerritt Canyon district (F, Fig. 6) identifi ed as a small quartz anomaly (Fig. 9). View is toward the north. Note scale at bottom left. Pointer 41°23'16.31"N, 115°58'17.10"W. Elevation 7774 ft. Eye alti- tude 8562 ft. Scale bar is 497 ft (151.5 m). Image © 2007 DigitalGlobe; © 2007 Europa Technologies; © 2007 TerraMetrics. The jasperoid is localized by the Bidart anticline and is hosted in unit 1 of the Hanson Creek Formation (Silurian–Ordovician) that was silicifi ed during the Eocene (Hofstra et al., 1999). Inset shows fi eld photograph of jasperoid from Eliason and Wilton (2005).

Hydrothermal Quartz and Carbonate investigations of known mineralization. Sizable is either an insuffi cient percent and volume of occurrences of quartz formed by hydrothermal carbonate present to be detected, or it occurs Plate 3 shows that there is a high correla- processes were identifi ed that are associated within carbonate sedimentary rocks such that tion between identifi ed quartz and jasperoids with Carlin-type Au (Hofstra and Cline, 2000; there is no spectral contrast. In volcanic rocks, of uncertain age and undefi ned relation to ore Cline et al., 2005), distal-disseminated Au-Ag calcite-bearing propylitic alteration has not yet deposits (outlined in orange). Such correlation (Cox, 1992; Theodore, 1998), and epithermal been conclusively identifi ed using ASTER TIR is especially high in White Pine County, where high- and low-sulfi dation Au-Ag (John, 2001) data, as the calcite is typically present in only jasperoids were well mapped and differenti- deposits. Siliceous sinters associated with mod- low abundance and mixed with other minerals ated by Hose et al. (1976). Below, mineral indi- ern hot springs (Shevenell and Garside, 2005) such as chlorite and epidote. In the TIR, chlo- ces are compared to geologic maps of various were also mapped (Fig. 11). rite and epidote are characterized by a decrease scales (1:250,000–1:6000) from mining districts Other than several occurrences of travertine in emissivity between ASTER bands 11 and and geothermal areas that are known to contain associated with hot springs (Fig. 11), carbon- 13, and a slight increase in emissivity between large exposures of hydrothermal quartz. In a ate of hydrothermal origin is diffi cult to recog- bands 13 and 14 (Salisbury et al., 1991). These few areas, detected quartz prompted literature nize on the carbonate index map because there spectral properties are similar to those of mafi c

234 Geosphere, February 2008

and/or ultramafi c minerals and suggest that the Shale, and Devonian Guilmette Formation (Dg) tion (Dg, limestone and dolomite), Pilot Shale, compound ratio (band 11 + band 12 + band limestone, and especially at contacts between Joana Limestone, and Eocene conglomerate 14)/(band 13 × 3), or previously developed indi- these formations. The Jerritt Canyon district, (not shown) was identifi ed. ASTER SWIR data ces for mafi c and/or ultramafi c minerals includ- in the Independence Mountains, also has some show that some of the jasperoids in the Pilot ing (band 12 + band 14)/(band 13 × 2) (Rowan large jasperoids, especially in the lower part of Shale are accompanied by signifi cant argilliza- et al., 2005) and (band 12 × band 14)/(band 13) the Silurian and Devonian Roberts Mountains tion (mainly kaolinite), while in adjacent areas (Ninomiya et al., 2005), can be used to isolate Formation and upper part of the Ordovician sericite (most likely muscovite) was identifi ed. chlorite and epidote from carbonate minerals and Silurian Hanson Creek Formation (Hofstra A large quartz anomaly was mapped on the west in areas with very sparse to nonexistent vegeta- et al., 1999). In the largest gold trends (Carlin, side of the Bald Mountain district in the chaotic tion cover and limited weathering, and where CN, Fig. 6; Battle Mountain–Eureka, BM/EK; breccia unit [JB(4), Fig. 12]. Although some of the minerals are not intimately mixed. Given Getchell, GT), jasperoids are generally smaller, this quartz could be due to brecciated Diamond the spectral resolution of ASTER TIR data, it but the largest jasperoids present also are typi- Peak Formation and silicifi ed Chainman Shale, is unlikely that they can be used to accurately cally developed in certain limestone units and jasperoid in the hanging wall of the north- differentiate chlorite and epidote from mafi c along shale-limestone contacts. Consequently, northwest–striking Ruby listric normal fault is and/or ultramafi c minerals such as hornblende, quartz identifi ed using ASTER TIR data in the likely Miocene in age (C. Nutt, 2007, personal actinolite, tremolite, biotite, olivine, augite, and above-mentioned units is likely to be jasperoid. commun.). An ASTER emissivity spectrum for diopside. It is also possible that ASTER visible, Several examples from these trends and districts an exposure of the jasperoid in Water Canyon NIR, and SWIR data can be used to differentiate are described below. shows a strong quartz signature (Fig. 4). chlorite and epidote (as a group) from carbon- In the adjacent Bald Mountain and Alliga- In the area surrounding the Illipah Au deposit ates by exploiting the deep absorption caused tor Ridge districts (Fig. 12), jasperoids of four at the north end of the White Pine Range (J, by ferric/ferrous iron centered around 1.0 µm different ages have been recognized: (1) small Fig. 6), the large jasperoid hosted in Eocene that is present in chlorite and epidote (and many stratabound jasperoids hosted in Cambrian– conglomerate and underlying Joana Limestone, mafi c minerals) but not in pure carbonates Ordovician Formations that predate Jurassic described and photographed by Nutt and Hofs- (Hewson et al., 2005). In other areas, propylitic intrusions, (2) small discordant jasperoids asso- tra (2003), was mapped using the ASTER TIR calcite and epidote have been identifi ed using ciated with Jurassic reduced intrusion-related data (Fig. 13). This jasperoid forms the cap rock ASTER SWIR data (Rockwell et al., 2006), gold deposits hosted in Cambrian–Mississip- of the fl at-topped ridge 2 km southeast of the and are readily discernable with spectroscopic pian Formations, (3) large stratabound jasper- Illipah mine. High quartz indices correspond data such as AVIRIS (Airborne Visible/Infrared oids associated with Eocene Carlin-type gold well with the mapped jasperoid in that area Imaging Spectrometer) (Rockwell et al., 2000, deposits hosted in Devonian–Mississippian from Crafford (2007). South of the jasperoid, 2005; Rowan and Mars, 2003; Cunningham et Formations, and (4) large jasperoids hosted in the ridge is underlain by unaltered Joana Lime- al., 2005), HyMap, or HyperSpecTIR, although a chaotic breccia unit of Eocene–Miocene age stone (Mj within the composite MDcl unit of intimate mixing of these minerals can cause dif- (Nutt and Hofstra, 2003, 2007; Nutt and Hart, Crafford, 2007) that was identifi ed as carbonate. fi culties (Dalton et al., 2004). In Paleozoic car- 2004). Of these, only the latter two are large In this area (Fig. 13), the Diamond Peak Forma- bonate rocks, the distribution of hydrothermal enough to discern between areas disturbed tion (Mdp) consistently shows moderate to high dolomite occurrences can be used to map fl ow by mining using the ASTER TIR data. Those quartz index values. paths of hot basinal brines that generate SEDEX associated with Carlin-type deposits, such as In the Easy Junior mining district (E, Fig. 6), (sedimentary exhalative) and MVT (Mississippi Winrock (W, Fig. 12), Galaxy (G), Horseshoe the same composite Devonian to Mississippian Valley type) deposits (e.g., Diehl et al., 2005). (H), Saga (S), and others [JB(1–3) and J1, Fig. MDcl unit hosts a series of jasperoids mapped by Dolomite is nearly impossible to differentiate 12], are localized by north-striking faults along Crafford (2007, br, outlined in orange in Plate 3) from its host using ASTER TIR data alone. Mooney Basin and intersecting northwest-strik- and Carden (1991) that were all mapped using Since dolomite usually exhibits higher carbon- ing faults of the Bida trend (BT, Fig. 12). The the ASTER TIR data (Fig. 14). Likewise, the ate index values than calcite, it is possible that Bida trend also served to localize the Jurassic Devonian Devils Gate Limestone (Dd) within dolomitization within a limestone unit could be Bald Mountain stock and related deposits. Jas- the Dc unit of Crafford (2007) was identifi ed as recognized as discrete areas of high carbonate peroids exposed in and adjacent to the Carlin- carbonate (Table 3). index values, although no examples have yet type deposits are hosted in Chainman Shale In the Independence Mountains (F, Fig. 6), a been found. ASTER SWIR data are better suited (Mch of Nutt and Hart, 2004), Joana Limestone massive jasperoid hosted in interbedded chert the problem and have been used to distinguish (Mj and jasperoid Mjj), and Pilot Shale (MDp). and carbonate rocks of the Ordovician–Silurian calcite from dolomite (Rowan and Mars, 2003). In the Bida trend, between the Eocene Horse- Hanson Creek Formation (unit 1, Hofstra et al., shoe deposit and the Jurassic Top deposit (T, 1999) was mapped (Fig. 9). While this ridge- Carlin-Type Au Deposits Fig. 12), quartz was identifi ed on a low ridge in forming jasperoid (Fig. 10) would be considered Many Carlin-type gold deposits are associated an area underlain by Pilot Shale and Chainman to be large by most economic geologists, it is with jasperoids formed by pervasive silicifi cation Shale (J2, Fig. 12). ASTER SWIR data indicate relatively small in terms of the ASTER TIR data of carbonates, shales, or conglomerates (Hofstra that these rocks have been highly argillized to (16 90 m pixels identifi ed as quartz, including and Cline, 2000). Some of the largest jasperoids kaolinite. The large size and typical host of surrounding fl oat). Most of the other large jas- are associated with gold deposits in the Alligator the J2 quartz anomaly suggest that it may be a peroids associated with Carlin-type Au deposits Ridge trend (Nutt and Hofstra, 2003) and neigh- remote manifestation of the Eocene Carlin-type in the Jerritt Canyon district were detected in boring deposits in east-central Nevada (Maher, hydrothermal system that extends into the older areas disturbed by mining, as discussed later. 1997). In these deposits, the largest jasperoids Bald Mountain district. Farther south, between In the Carlin Trend, quartz was mapped in are stratabound and are frequently present in the Vantage and Yankee deposits, a large jasper- the Silurian–Lower Devonian Roberts Moun- the Chainman Shale, Joana Limestone, Pilot oid (J3, Fig. 12) hosted in the Guilmette Forma- tain Formation 3.3 km north of the main open

Geosphere, February 2008 235

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra ed at ed ed in trav- ow deposits ow Figure 5. To access a full-resolution PDF of this PDF access a full-resolution To 5. Figure in Plate 3. Quartz or carbonate was not identifi in Plate 3. Quartz or ed at the Geysers and Beowawe hot springs, Eureka ed using the ASTER (Advanced Spaceborne Thermal Emission ASTER (Advanced Spaceborne ed using the ed between the Geysers and Beowawe that represents outfl ed between the Geysers and Beowawe that represents cant quartz was identifi ank of Ruby Mountains in Ruby Valley, Elko County (H, Fig. 6). (B) Carbonate identifi Valley, ank of Ruby Mountains in ed at hot springs along east fl ection Radiometer) data. (A) Quartz identifi gure, please visit http://dx.doi.org/10.1130/GES00126.S10 or the full-text article on www.gsajournals.org. or please visit http://dx.doi.org/10.1130/GES00126.S10 gure, Figure 11. Subsets of Plate 3 showing modern hot springs at which siliceous or travertine sinter deposits were identifi deposits were travertine sinter Subsets of Plate 3 showing modern hot springs at which siliceous or 11. Figure and Refl Nye County (I, Fig. 6). (C) Quartz identifi Valley, Punchbowl hot springs in Monitor ertine deposits at Potts Ranch and Diana’s County (G, Fig. 6). Geology polygons are not shown in B and C for simplicity. Signifi simplicity. not shown in B and C for County (G, Fig. 6). Geology polygons are from the Geysers spring. Sinters and/or tufa deposits (QThs) from the geology coverage of Crafford (2007) are outlined in cyan the geology coverage of Crafford (2007) are tufa deposits (QThs) from the Geysers spring. Sinters and/or from shown in Punchbowl, and Potts Ranch hot springs are ASTER emissivity spectra of the Beowawe, Diana’s several of these deposits. fi

236 Geosphere, February 2008

Figure 12. Subset of Plate 3 over the Bald Mountain and Alligator Ridge districts, White Pine County (M, Fig. 6). Quartz-bearing units are indicated in magenta, carbonate-bearing units in blue, and jasperoids in orange (Crafford, 2007). Mdp—Diamond Peak Formation. Dd— Devonian Guilmette Formation limestone (labeled Devils Gate Formation in Crafford, 2007). Dn—Devonian Nevada Formation (mainly dolomite), Simonson Dolomite, and/or Sevy Dolomite. DOd—Devonian–Ordovician dolomites, undivided. P&c—Riepe Spring and Ely Limestones, undivided. Oe—Ordovician Eureka Quartzite, Ordovician Pogonip Group (silty limestone ± sandstone), and/or Cambrian Windfall Formation (limestone with local interbedded chert and clastics). Bald Mountain district: BT—Bida trend; MB—Mooney Basin; Ji—Jurassic stock; SS1—sandstone beds and/or lenses of Pogonip Group on Big Bald Mountain; SS2—Permian Rib Hill Sandstone; J1— possible jasperoid in Pilot Shale along Mooney Basin trend; J2—quartz in argillized Pilot Shale and Chainman Shale, southeast of Top Pit area (T); W—Winrock deposit, jasperoid in Joana Limestone, Mjj of Nutt and Hofstra (2004) (Fig. 4); G—Galaxy deposit; H—Horseshoe deposit; S—Saga deposit; JB—jasperoid breccia (see text for explanation) from Crafford (2007). The Horseshoe and Galaxy deposits have been signifi cantly disturbed by mining. Alligator Ridge district: V—Vantage deposit; Y—Yankee deposit; J3—possible jasperoids in locally argillized Joana Limestone, Pilot Shale, and Guilmette Formation. ASTER (Advanced Spaceborne Thermal Emission and Refl ection Radi- ometer) emissivity spectra of several of the units and features in this fi gure are shown in Figures 4 and 5. To access a full-resolution PDF of this fi gure, please visit http://dx.doi.org/10.1130/GES00126.S11 or the full-text article on www.gsajournals.org.

Geosphere, February 2008 237

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra

pit of the Gold Quarry mine along the north- sponds to the sandstone, although silicifi cation in emissivity between bands 10 and 12 rela- east side of Maggie Creek Canyon (GQ, Fig. 6; and/or decalcifi cation may also be present. tive to quartz, Fig. 3). Quartz-bearing allu- Plates 1–3). This northwest-southeast–trending The small Kinsley mining district in eastern vium and/or tailings derived from the County zone of quartz appears to have high albedo sug- Elko County (C, Fig. 6) has small exposures of Line deposit (CL, Fig. 16) have been shed to gestive of bleaching, and corresponds in part to jasperoid that occur both within and outside the the northwest into Gabbs Valley along Fin- hydrothermal alteration mapped along a thrust pits. Comparison with the geologic map from gerock Wash (Plates 1–3). Silicifi cation was fault of similar strike (Fig. I-10 in Harlan et al., Lapointe et al. (1991) shows that both mined also identifi ed in the Santa Fe district located 2002). The composition of the Roberts Moun- and undisturbed jasperoids were successfully 20 km southwest of the Paradise Peak area in tain Formation ranges from a silty limestone identifi ed using the ASTER data (Fig. 15). This the Gabbs Valley Range (Fig. 6; Plates 1–3). to a calcareous siltstone, but no carbonate was example also shows that tiny jasperoids, such Silicifi cation identifi ed with the ASTER TIR detected on this outcrop using the ASTER data. as those located 2–3.5 km north-northeast of data that is directly associated with advanced Where decalcifi ed, the rocks consist mainly of the main mining area (“Main Zone”), are too argillic or phyllic hydrothermal alteration is fi ne-grained, platy siltstone with high quartz small to be resolved with the ASTER TIR data. commonly characterized by low to moderate content. Therefore, these outcrops with low to Quartz was also identifi ed in a heap leach pile quartz index values, whereas quartzites, sin- moderate quartz index values may be decalci- located 2 km east of the main mining area. The ters, and jasperoids with higher concentrations fi ed and/or silicifi ed. Smaller quartz-bearing Eocene pluton inferred to be responsible for of quartz commonly show moderate to high areas with low index values also were detected the mineralization is located 3.2 km south of index values. in an area of mapped alteration 1 km to the east, the main mining area along the southern edge in the vicinity of the Rainbow deposit (Harlan of the maps shown in Figure 15. Low-Sulfi dation Au-Ag and Hg Deposits et al., 2002). Outside the study area, a large body of relict High-Sulfi dation Au-Ag Deposits siliceous sinter associated with the Hasbrouck Pluton-Related Distal-Disseminated Deposits In the study area, the only high-sulfi dation Peak low-sulfi dation Au-Ag deposit in Esmer- Silicifi cation was generally not detected ore deposits of economic signifi cance associ- alda County is readily identifi able with ASTER along pluton contacts (Plate 2) or near proxi- ated with magmatic-hydrothermal acid-sulfate TIR data. It is therefore possible that areas with mal pluton-related ore deposits (Plate 1). How- alteration in volcanic rocks are the Paradise high quartz index values in the vicinity of the ever, small jasperoids are frequently present Peak Au-Ag-Hg deposit (K, Fig. 6) in Nye and McDermitt hot spring–type, low-sulfi dation Hg in or near open pit mines that produce gold Mineral Counties and the Santa Fe Au-Ag-Cu- deposit (MD, Fig. 6) in Humboldt County are from distal-disseminated deposits hosted in Pb-Sb-W district in Mineral County. Depos- sinters, although the surface disturbance caused sedimentary rocks (e.g., Robinson district, its of this type are restricted to the western by mining makes discrimination of such fea- Maher, 1996; Lone Tree and Marigold mines andesite assemblage of the Great Basin (John, tures diffi cult. in the Battle Mountain district, Theodore, 2001). Mineralization in the Paradise Peak Silicifi ed rocks associated with low-sul- 2000; Bald Mountain district, Nutt and Hofs- area is most likely the result of two hydro- fi dation deposits in the study area are for the tra, 2007). Quartz was detected in each of the thermal systems (John et al., 1989; Sillitoe most part too small to be directly identifi ed above mining areas, but it was diffi cult to fi nd and Lorson, 1994). The earlier of these sys- using the ASTER TIR data, although several exposures of jasperoid in adjacent areas that tems created porphyry-type quartz stockworks pixels containing quartz may be found that were undisturbed. For example, Maher (1996) enveloped by quartz-sericite-pyrite alteration are expressions of more extensive subsurface mapped hydrothermal silicifi cation within the with Au ca. 22 Ma in the County Line and silicifi cation and/or silicifi ed rocks that have marble halo at the Robinson porphyry Cu-Au East Zone deposits in the western section of been exposed by mining (e.g., Rawhide Au- deposit near Ely in White Pine County, but we the area. A later system formed intense silicic Ag district, Mineral County; RH, Fig. 6). An were unable to spatially discriminate quartz (quartz-pyrite ± opal), quartz-alunite, argil- exception is in the well-exposed high Jarbidge in outcrop from quartz in the pits and tailings. lic (quartz + clays), and propylitic (chlorite + Mountains of Elko County (JB, Fig. 6), where At Lone Tree (LT, Fig. 6) and Marigold (MG), clays) alteration with Au and Hg ca. 19–18 Ma abundant quartz was identifi ed above treeline the deposits are hosted in Havallah Sequence, in the Paradise Peak, Ketchup Flat, Ketchup within the Miocene Jarbidge Rhyolite (Plates Edna Mountain Formation, Battle Formation, Knob, and Ketchup Hills deposits in the east- 1–3; Tr3 of Crafford, 2007). These quartz and Valmy Formation that contain quartz sand- ern section of the area. Figure 16 shows that occurrences are some of the largest associated stones, siltstones, and chert, making it nearly quartz formed by both systems was identifi ed with volcanic terranes in the study area, and are impossible to distinguish hydrothermal quartz. using the ASTER TIR data. The highest quartz located several kilometers southeast of the Jar- At Bald Mountain (Fig. 12), most of the dis- index values correspond to tailings deposits bidge low-sulfi dation epithermal Au-Ag discordant jasperoids associated with the Jurassic just south of the Paradise Peak, Ketchup Flat, trict within the bimodal volcanic assemblage. distal disseminated deposit are small, diffi cult and Ketchup Hill deposits to the east. Mod- The Jarbidge deposit (ca. 14 Ma) is hosted to resolve, and only a few occur outside areas erate quartz index values are associated with within rhyolite lava fl ows and domes, and con- disturbed by mining. Quartz with moderate the quartz-alunite (QA, Fig. 16) alteration sists of laminated quartz-adularia-calcite veins, index values (SS1, Fig. 12) was identifi ed on within the Middle Tuffs (Tmt, 23 Ma) on and stockworks, and breccias within phyllically the summit ridge of Big Bald Mountain sev- around Newman Ridge in the central part of altered wallrock (Coats, 1964; Lapointe et al., eral kilometers north of the Top Pit area within the district. The quartz-sericite-pyrite altera- 1991; Bernt, 1998). The occurrences of quartz the Ordovician Pogonip Group. At this local- tion (QS, Fig. 16) is expressed by low quartz within the Jarbidge Rhyolite are highly anoma- ity, the Pogonip is composed primarily of silty index values and emissivity features sugges- lous, ridge forming, and locally associated limestone with thin beds and lenses of resistant tive of a mixture of quartz and illite or mus- with argillic and/or phyllic alteration detected quartz sandstone (C. Nutt, 2007, personal com- covite (i.e., reduced prominence of emissivity with the ASTER SWIR data. The north-north- mun.). Hence, the identifi ed quartz likely corre- peak at ASTER band 11 and greater decrease west–south-southeast trend of the main quartz

238 Geosphere, February 2008

Figure 13. Subset of Plate 3 over the Illipah Au mine in the northern White Pine Range, White Pine County (J, Fig. 6). In the map at top, quartz-bearing units are indicated in magenta, carbonate-bearing units in blue, and jasperoids in orange (Crafford, 2007). Note correspondence of identifi ed quartz with the Illipah mine area, jasperoids, and the Diamond Peak Formation (Mdp). Mj—Joana Limestone. P&c— Pennsylvanian–Permian Riepe Spring and Ely Limestones. Psc—Permian Arcturus Formation (siliciclastics, limestones, and dolomites) and/or Rib Hill Sandstone. Also note identifi ed carbonate within the limestone-bearing units. Image at bottom shows perspective view from Google Earth™ looking southeast over the mine toward the jasperoid, which forms the fl at top of the ridge in the background (Nutt and Hofstra, 2003). Cyan arrow in the map at top indicates the look direction of the perspective view. ASTER—Advanced Spaceborne Thermal Emission and Refl ection Radiometer. To access a full-resolution PDF of this fi gure, please visit http://dx.doi.org/10.1130/GES00126.S12 or the full-text article on www.gsajournals.org.

Geosphere, February 2008 239

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra gure, please visit http://dx.doi.org/10.1130/ gure, hale, Joana Limestone, and Chainman Shale, cor- right. Quartz-bearing units are indicated in magenta, right. Quartz-bearing units are ed quartz with the Nighthawk Ridge mine area, jasperoids (br), and the jasperoids ed quartz with the Nighthawk Ridge mine area, ed quartz occurrences not included in the geology coverage of Crafford (2007) that ed quartz occurrences ed from Carden (1991). Dc—Devils Gate Limestone (note correspondence with identi- Carden (1991). Dc—Devils Gate Limestone (note correspondence ed from ection Radiometer. To access a full-resolution PDF of this fi PDF access a full-resolution To ection Radiometer. Mcl unit of Crafford, 2007). JP—identifi & ed carbonate). ASTER—Advanced Spaceborne Thermal Emission and Refl ASTER—Advanced Spaceborne ed carbonate). carbonate-bearing units in blue, and jasperoids in orange (Crafford, 2007). Note correspondence of identifi in orange (Crafford, 2007). Note correspondence carbonate-bearing units in blue, and jasperoids within the Diamond Peak Formation (included here within the MDcl unit of Crafford (2007) that includes Pilot S These quartz bodies mainly occur likely to be jasperoids. are on the map at left, which has been modifi indicated in red well to mapped jasperoids respond fi Figure 14. Subset of Plate 3 over the Easy Junior mining district in White Pine County (E, Fig. 6). Railroad Valley is at lower Valley White Pine County (E, Fig. 6). Railroad mining district in the Easy Junior 14. Subset of Plate 3 over Figure the full-text article on www.gsajournals.org. GES00126.S13 or

240 Geosphere, February 2008

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Remote identifi cation of quartz and carbonate minerals, Nevada ed The ection Radiometer) data. limestones and dolomites of the Cambrian Windfall Windfall limestones and dolomites of the Cambrian Maps are overlain on background of Landsat Thematic of Landsat overlain on background Maps are aps, near the Phalen mine. Abundant carbonate was identifi the Phalen mine. aps, near and heap leach to both mined and undisturbed jasperoids, cation of quartz corresponding ed using the ASTER (Advanced Spaceborne Thermal Emission and Refl ASTER (Advanced Spaceborne ed using the gure, please visit http://dx.doi.org/10.1130/GES00126.S14 or the full-text article on www.gsajournals.org. or please visit http://dx.doi.org/10.1130/GES00126.S14 gure, Figure 15. Subset of quartz and carbonate index maps over Kinsley mining district, Mountains, Elko County (C, Fig. 6). 15. Subset of quartz and carbonate index maps over Figure Lapointe et al. (1991). Note identifi is at right. Map left from Valley Antelope data. Mapper too small to be identifi right of geologic map were in upper pile. Patchy jasperoids Tertiary intrusion responsible for the distal-disseminated mineralization in district is located at south edge of m for intrusion responsible Tertiary within limestones of the Ordovician Pogonip Group (Op) that underlie most of the range to the north of Au deposits, and within (Op) that underlie most of the range to north within limestones of the Ordovician Pogonip Group Formation to the south. To access a full-resolution PDF of this fi PDF access a full-resolution To Formation to the south.

Geosphere, February 2008 241

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra

Figure 16. Subset of Plate 3 over the Paradise Peak mine area, Nye and Mineral Counties (K, Fig. 6). Map at top was modiﬁ ed from Sillitoe and Lorson (1994). QS—Au-bearing porphyry-type quartz-sericite-pyrite stockworks (ca. 22 Ma). QA—Au/Hg-bearing quartz-alunite alteration (ca. 19–18 Ma) on and around Newman Ridge. CL—County Line deposit. EZ—East Zone deposit. PP—Paradise Peak deposit. KH—Ketchup Hill deposit. KF—Ketchup Flat deposit. KK—Ketchup Knob deposit. To access a full-resolution PDF of this ﬁ gure, please visit http://dx.doi.org/10.1130/GES00126.S15 or the full-text article on www.gsajournals.org.

242 Geosphere, February 2008

occurrence in the Jarbidge Mountains parallels ite being generally more abundant. The use of ure 5, but most show a slight emissivity peak at local faults (Plate 2), and corresponds to the “east only expression (a) of equation 1 as a quartz ASTER band 11 indicative of quartz. It is pos- vein system” of Au- and Ag-bearing quartz-adu- index would likely eliminate the dunes from sible that clearing has exposed sandy soils con- laria veins described by Schrader (1923) and the quartz index map, as the TIR spectra of the taining quartz and loess. Coats et al. (1977). Numerous prospect pits and dunes in bands 10–12 differ substantially from Quartz was mapped at the Colado/Perlite adits are located high on the ridge along the sys- that of quartz, as mentioned above. However, as diatomite mine and associated ore storage areas tem, principally along shear zones with quartz the emissivity increase between bands 12 and along Interstate 80 4 km south of Woolsey in veins and limonitic staining that can extend for as 13 exploited by expression (b) of equation 1 is Pershing County (CP, Fig. 6). Other diatomite much as 900 m. The size of the quartz anomaly so strong for most quartz exposures, eliminat- mines such as the Trinity and Brady’s mines is increased by colluvium, landslide deposits, and ing expression (b) from the quartz index would in Humboldt and Pershing Counties (outside glacial moraines derived from the altered rocks likely also result in an index map degraded in of study area) also showed strong quartz index forming the ridge. While it is possible that the terms of overall accuracy and detail. values. Most diatomite deposits occur within the identifi ed quartz is related to highly silicic and Carbonate was identifi ed in playas within sedimentary unit Ts3 on the statewide geology perhaps glassy and/or perlitic fl ows or domes of Buena Vista Valley in Pershing County (BV, map (Ludington et al., 2005), although most the Jarbidge Rhyolite, the relationships described Fig. 6) and in the northeastern and eastern parts undisturbed diatomite deposits from the Mineral above suggest it is likely due to silicifi cation of of Carson Sink in Churchill County (CS, Fig. Resource Data System (MRDS) (2007) showed rhyolite along shear zones, at least in part. 6). Fine eolian deposits of silicates (clays and no appreciable quartz index response. Diatom illite/mica), calcite, and soluble salts are pres- phytoplankton commonly contain frustules of Surfi cial Geologic Features Containing ent on the Carson Sink surface, and the car- opaline silica, and thus could be identifi ed in Quartz and Carbonate bonate and soluble salts increase in abundance greater detail using SWIR remote sensing data, downwind, toward the northeast (Chadwick and including those of ASTER. Quartz was identifi ed within playa lake depos- Davis, 1990). The calcite is most likely an eolian Quartz was also mapped within rhyolitic units its and in sand dunes. While most of the quartz deposit derived in part from Tertiary limestones (Tr3 and Tt2, Table 2) locally associated with occurrences in and adjacent to playa lakes in the and/or Quaternary tufa from the upwind areas of perlite deposits. In addition to the possibly per- western half of the study area are likely to be the Carson Sink to the southwest, including the litic zones of the Jarbidge Rhyolite, quartz was thick deposits of beach sand, some may repre- Hot Springs Mountains region (Kratt, 2005). mapped within and near the Palisade Canyon sent sinter deposits or eolian dusts derived from perlite prospect (PC, Fig. 6) in Eureka County, them. For example, excellent correlation exists Quartz and Carbonate Related to and within the Monotony Tuff and Lava, north- between the outline of a large playa in Edwards Anthropogenic Features ern Nye County, near the Pamela Placer perlite Creek Valley in Churchill County (playa center prospect (PP, Fig. 6; MRDS, 2007). at 39°38′27′′N, 117°39′12′′W; Ludington et al., In addition to many areas disturbed by min- 2005; Crafford, 2007) and quartz mapped using ing such as pits, tailings deposits, and heap leach CONCLUSIONS the ASTER data (Plates 1–3). The identifi cation piles, quartz was identifi ed along Interstate 80 of these sand deposits could be useful for future (Figs. 7 and 8; Plates 1–3), within most urban This research demonstrates several charac- geomorphology studies and surfi cial and/or areas, and on one of the two intersecting runways teristics of ASTER TIR data, the processing Quaternary geologic mapping. Figure 17 dem- of the airport near the town of Battle Mountain and analysis methods applied to them, and the onstrates how quartz identifi ed in Silver State (Plate 1). Quartz was not identifi ed along smaller utility of the data for mapping quartz and car- Valley in Humboldt County corresponds to the roads because they were unresolvable given the bonate minerals. The generally high correla- Winnemucca Dunes. These dunes were identi- 90 m GIFOV of the ASTER TIR data. It is pre- tion between identifi ed quartz and carbonate fi ed as quartz based mainly on the basis of the sumed that the spectral similarity of these features and corresponding lithologies, alteration types, steep increase in emissivity between ASTER with the reference spectrum of quartz (Fig. 1) is unconsolidated surfi cial material, and anthropo- bands 12 and 13 (Fig. 5), as the spectral shape caused by the presence of quartz in aggregate genically disturbed areas containing these min- between bands 10 and 12 does not correspond used to make concrete and asphalt (macadam), erals is testament to the radiometric stability and well to that of quartz (Fig. 1). The signifi cant as described above in Methods. However, it is resolution of the ASTER data in this wavelength decrease in emissivity between bands 10 and unknown if uncorrected temperature effects from region. The accuracy of the automated TES 12 suggests that other minerals, possibly clay the TES calibration process (Gillespie et al., 1998) algorithm (Gillespie et al., 1998), the strong and minerals and/or gypsum (Fig. 3), are present in play a role in the detection of quartz in some or all unambiguous nature of the mid-infrared spectral the dunes. Abundant loess with clays ± micas of these features. features of quartz and carbonate at ASTER sam- derived from defl ation of pluvial lakes is pres- Several large occurrences of apparently pling and bandpass, and the utility of the ratio- ent in soils and within the matrix of colluvial quartz-bearing soils were identifi ed 40 km north based analysis methodologies presented here to deposits in the Osgood Mountains (Getchell of the town of Battle Mountain and west of Six- exploit these spectral signatures also contributed Trend, GT, Fig. 6) and exposed in the drainages mile Hill in western Elko and eastern Humboldt to the success of this effort. of Kelly and Evans Creeks to the east (Rock- Counties, including the Evans Creek drainage These analysis methods are ideal for cost-effec- well, 1991). Sand dunes containing quartz and (QS, Fig. 6). The edges of these occurrences tive mineral mapping using ASTER data. For gypsum are common in areas with abundant are sharp and most are oriented north-south and example, they can be used as a tool for guiding pluvial lakes (Chen et al., 1995; Wilkins, 2000). east-west, indicating that they represent areas fi eld mapping and sampling in frontier areas, and Preliminary analysis of corresponding ASTER that have been cleared of rangeland vegetation, as baselines for more targeted airborne imaging SWIR data of the Winnemucca Dunes suggests possibly for grazing or agricultural use. The spectrometer surveys. For maximum effective- that montmorillonite and gypsum are present emissivity spectra of these areas are similar to ness, however, spectral analysis of ASTER vis- in variable concentrations, with montmorillon- those of the Winnemucca Dunes shown in Fig- ible and NIR (for mapping of iron minerals,

Geosphere, February 2008 243

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra pondence of white to light gray dunes in top ted quartz is shown in red. Image at top shows ted quartz is shown in red. ection Radiometer) emissivity spectrum of the dunes. To access a full-resolu- To ection Radiometer) emissivity spectrum of the dunes. gure, please visit http://dx.doi.org/10.1130/GES00126.S16 or the full-text article on www.gsajournals.org. or please visit http://dx.doi.org/10.1130/GES00126.S16 gure, Figure 17. Bottom map is a subset of Plate 2 over the Winnemucca Dunes, Silver State Valley, Humboldt County (D, Fig. 6). Detec Valley, State Dunes, Silver Winnemucca the 17. Bottom map is a subset of Plate 2 over Figure Landsat Thematic Mapper data from the U.S. Geological Survey Seamless Data Distribution System (bands 4,3,2/R,G,B). Note corres data from Thematic Mapper Landsat image to detected quartz. See Figure 5 for an ASTER (Advanced Spaceborne Thermal Emission and Reﬂ ASTER (Advanced Spaceborne an 5 for image to detected quartz. See Figure of this ﬁ tion PDF

244 Geosphere, February 2008

silver vein formation in the Jarbidge Mountains, Elko vegetation, and volatiles including water) and parisons of mineral index maps with large-scale County, Nevada [abs.]: Reno, Geological Society of SWIR data (for phyllosilicates, sulfates, carbon- lithostratigraphic maps can reduce the uncertainty Nevada Newsletter, January 1998. ates, amphiboles, some sorosilicates, and hydrous of interpretations. Future experimentation is war- Carden, J.R., 1991, The discovery and geology of the Nighthawk Ridge deposit at Easy Junior, White Pine County, Nevada, silica) should accompany TIR analysis, especially ranted regarding the use of known exposures of in Raines, G.L., et al., eds., Geology and ore deposits of the when characterizing hydrothermal alteration. The hydrothermal quartz as training sites for super- Great Basin: Symposium Proceedings, April 1–5, 1990: Reno, Geological Society of Nevada, 1257 p. semiautomated application of these methods to vised classifi cation techniques, including Spectral Chadwick, O.A., and Davis, J.O., 1990, Soil-forming inter- many scenes acquired on different dates, though Angle Mapper (Kruse et al., 1993; Rowan et al., vals caused by eolian sediment pulses in the Lahon- largely successful, resulted in some sharp inter- 2005). This analysis approach has the potential tan Basin, northwestern Nevada: Geology, v. 18, p. 243–246, doi: 10.1130/0091-7613(1990)018<0243: scene variations in mineral index values. How- for discriminating hydrothermal and sedimentary SFICBE>2.3.CO;2. ever, when applied to individual ASTER scenes, and/or metamorphic quartz based on statistical Chen, X.Y., Chappell, J., and Murray, A.S., 1995, High the mineral detection thresholds for density slic- measures of overall spectral shape on a scene-by- (ground) water levels and dune development in central Australia; TL dates from gypsum and quartz dunes ing the index maps can be further optimized for scene basis. around Lake Lewis (Napperby), Northern Territory: the atmospheric, soil moisture, noise, viewing The ASTER-derived quartz and carbonate Geomorphology, v. 11, p. 311–322, doi: 10.1016/0169- 555X(94)00072-Y. geometry, and solar illumination characteristics of mineral maps provide essential, reconnaissance- Clark, R.N., 1999, Spectroscopy of rocks and minerals, and that scene. level information relevant to future assessments principles of spectroscopy, in Rencz, A.N., ed., Remote Because of the low spectral and spatial reso- of mineral resource potential and detailed geo- sensing for the Earth sciences, Manual of remote sensing, Volume 3 (third edition): New York, John Wiley and lutions of the ASTER TIR data and the nature logic mapping of rocks, surfi cial deposits, and Sons, Inc., p. 3–58. of mineral spectral features in the mid-infrared, anthropogenic disturbances related to mining Cline, J.S., Hofstra, A.H., Muntean, J.L., Tosdal, R.M., minimum mineral detection limits are high, and and remediation activities. The results from and Hickey, K.A., 2005, Carlin-type gold deposits in Nevada—Critical geologic characteristics and viable thus only the largest and most thickly bedded this well-studied area of Nevada demonstrate models: Economic Geology, 100th Anniversary Vol- exposures of quartz and carbonate minerals some of the strengths and weaknesses of exist- ume, p. 451–484. Coats, R.R., 1964, Geology of the Jarbidge quadrangle, Nevada: could be identifi ed. Despite the limitations of ing geologic maps compiled at various scales. U.S. Geological Survey Bulletin 1141-M, 24 p. resolution, the results show that several differ- The results suggest that much remains to be Coats, R.R., 1987, Geology of Elko County, Nevada: Nevada ent types of hydrothermal systems deposited learned about the distribution and compositions Bureau of Mines and Geology Bulletin 101, 112 p. Coats, R.R., Green, R.C., and Cress, L.D., 1977, Mineral bodies of hydrothermal quartz of suffi cient size of unconsolidated surfi cial material in the study resources of the Jarbidge Wilderness and adjacent and mineral abundance to be detected. Notable area and their relations to exhumation, erosion, areas, Elko County, Nevada: U.S. Geological Survey among these are Carlin-type gold deposits, distal and fl uvial and lacustrine processes. The abil- Bulletin 1439, 79 p. Cox, D.P., 1992, Descriptive model of distal disseminated Ag- disseminated deposits, high- and low-sulfi dation ity to distinguish individual quartz- and carbon- Au, in Bliss, J.D., ed., Developments in deposit modeling: epithermal deposits, and sinter in geothermal ate-bearing units and features, especially within U.S. Geological Survey Bulletin 2004, p. 20–22. Crafford, A.E.J., 2007, Geologic map of Nevada: U.S. Geo- areas. TIR data of increased spectral and spatial complex and/or undifferentiated terranes, is of logical Survey Data Series 249, scale 1:250,000, http:// resolution would provide results of much greater obvious utility for poorly studied or frontier pubs.usgs.gov/ds/2007/249/. detail and accuracy, and allow for the identifi - areas where it can both guide fi eld mapping pro- Crowley, J.K., Brickey, D.W., and Rowan, L.C., 1989, Air- borne imaging spectrometer data of the Ruby Moun- cation of a greater variety of pure and mixed grams and aid mineral resource investigations. tains, Montana: Mineral discrimination using relative minerals and rock types at lower abundances. absorption band-depth images: Remote Sensing of Airborne thermal sensors such as the MODIS ACKNOWLEDGMENTS Environment, v. 29, p. 121–134. Cunningham, C.G., Rye, R.O., Rockwell, B.W., Kunk, M.J., (Moderate Resolution Imaging Spectroradiom- and Councell, T.B., 2005, Supergene destruction of a We thank the U.S. Geological Survey (USGS) eter)/ASTER (MASTER) simulator (25 TIR hydrothermal replacement alunite deposit at Big Rock Land Processes Distributed Active Archive Center Candy Mountain, Utah—Mineralogy, spectroscopic spectral bands, 5–50 m GIFOV; Hook et al., (LP DAAC), the National Aeronautics and Space remote sensing, stable-isotope, and argon-age evi- 2001) and SEBASS (256 SWIR and TIR spec- Administration Earth Observing System Data and dences: Chemical Geology, v. 215, p. 317–337, doi: tral bands, 2+ m GIFOV; Kirkland et al., 2002) Information System (EOSDIS), and Japan’s Earth 10.1016/j.chemgeo.2004.06.055. Dalton, J.B., Bove, D.J., Mladinich, C.S., and Rockwell, currently offer better mineral mapping capabil- Remote Sensing Data Analysis Center (ERSDAC) for providing the Advanced Spaceborne Thermal Emis- B.W., 2004, Identifi cation of spectrally similar mate- ity at local scales that ASTER (e.g., Vaughan et sion and Refl ection Radiometer (ASTER) data that rials using the USGS Tetracorder algorithm: The al., 2005). SWIR remote sensing data, including calcite–epidote–chlorite problem: Remote Sensing were the foundation of this research. We thank Paul of Environment, v. 89, p. 455–466, doi: 10.1016/ those of ASTER, can be used to obtain maps of Denning of the USGS for providing the Landsat data j.rse.2003.11.011. much greater spatial and mineralogical detail from the USGS Seamless Data Distribution System, Diehl, S.F., Hofstra, A.H., Emsbo, P., Koenig, A., Vikre, the shaded-relief digital terrain model, and a portion of P., and Lufkin, J., 2005, Distribution of hydrothermal regarding pure and mixed assemblages of car- Elizabeth Crafford’s geology coverage of Nevada that zebra dolomite and its relation to base and precious bonate minerals, and hydrous quartz minerals was subsequently modifi ed for use in this paper. We metal deposits in the Great Basin, in Rhoden, H.N., et including opal and chalcedony. also thank Jack Salisbury for information regarding al., eds., Window to the world: Geological Society of the thermal spectral properties of road surfaces, David Nevada Symposium, Reno, Nevada, May 14–18 2005: This paper also demonstrates that TIR spectral Reno, Geological Society of Nevada, p. 187–208. John for information on the Paradise Peak deposit and features of quartz formed by hydrothermal and Earth Remote Sensing Data Analysis Center (ERSDAC), Santa Fe district, and Alan Wallace for data on diato- sedimentary and/or metamorphic processes are 2005, ASTER User’s Guide, Part 1, General, Version mite deposits. Special thanks to Elizabeth Crafford, 4.0: http://www.science.aster.ersdac.or.jp/en/documnts/ quite similar at ASTER spectral resolution (Figs. Bernard Hubbard, and Alan Wallace for their thorough users_guide/part1/pdf/Part1_4E.pdf. 4 and 5). Variations in emissivity levels and rest- and insightful reviews of this manuscript. Eliason, R., and Wilton, D.T., 2005, Relation of gold mineralization to structure in the Jerritt Canyon district, strahlen band depths do not appear to be system- in REFERENCES CITED Nevada, Rhoden, H.N., et al., eds., Window to the atic enough to permit the reliable discrimination world: Geological Society of Nevada Symposium, of quartz by genetic process type. Recognition Reno, Nevada, May 14–18 2005: Reno, Geological ASTER Spectral Library, 2002, Spectra of man-made materi- Society of Nevada, p. 335–356. of hydrothermal quartz or carbonate minerals als derived from Nonconventional Exploitation Factors Gillespie, A.R., Matsunaga, T., Rokugawa, S., and Hook, is mainly a problem of geologic context in that (NEF) database, National Photographic Interpretation S.J., 1998, Temperature and emissivity separation from their identifi cation is facilitated in rocks com- Center: http://speclib.jpl.nasa.gov/archive/JHU/becknic/ Advanced Spaceborne Thermal Emission and Refl ec- manmade/manmade.txt. tion Radiometer (ASTER) images: IEEE Transactions posed mainly of other minerals. As such, com- Bernt, J.D., 1998, Volcanism, tectonic evolution, and gold- on Geoscience and Remote Sensing, v. 36, p. 1113–

Geosphere, February 2008 245

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021 Rockwell and Hofstra

1126, doi: 10.1109/36.700995. Preliminary integrated geologic map databases for the alunite deposit, Marysvale volcanic fi eld, Utah: Evi- Harlan, J.B., Harris, D.A., Mallette, P.M., Norby, J.W., Rota, United States, western States: California, Nevada, Ari- dence of a magmatic component: Economic Geology J.C., and Sagar, J.J., 2002, Geology and mineralization zona, Washington, Oregon, Idaho, and Utah, Version and the Bulletin of the Society of Economic Geolo- of the Maggie Creek district, in Thompson, T.B., et al., 1.2: U.S. Geological Survey Open-File Report 2005- gists, v. 101, p. 1377–1395. eds., Gold deposits of the Carlin Trend: Nevada Bureau 1305, http://pubs.usgs.gov/of/2005/1305/. Rowan, L.C., and Mars, J.C., 2003, Lithologic mapping in the of Mines and Geology Bulletin 111, p. 115–142. Maher, B.J., 1997, Mississippian sedimentary rock-hosted Mountain Pass, California area using Advanced Space- Hewson, R.D., Cudahy, T.J., Mizuhiko, S., Ueda, K., and gold deposits of the eastern Great Basin: Relative borne Thermal Emission and Refl ection Radiometer Mauger, A.J., 2005, Seamless geological map gen- importance of stratigraphic and structural ore controls: (ASTER) data: Remote Sensing of Environment, v. 84, eration using ASTER in the Broken Hill–Curnamona Society of Economic Geologists Guidebook Series, p. 350–366, doi: 10.1016/S0034-4257(02)00127-X. province of Australia: Remote Sensing of Environment, v. 28, p. 171–182. Rowan, L.C., Mars, J.C., and Simpson, C.J., 2005, Litho- v. 99, p. 159–172, doi: 10.1016/j.rse.2005.04.025. Maher, D., 1996, Stratigraphy, structure, and alteration of logic mapping of the Mordor, NT, Australia ultramafi c Hofstra, A.H., and Cline, J.S., 2000, Characteristics and igneous and carbonate wall rocks at the Veteran Exten- complex by using the Advanced Spaceborne Ther- models for Carlin-type gold deposits, in Hagemann, sion in the Robinson (Ely) porphyry copper district, mal Emission and Refl ection Radiometer (ASTER): S.G., and Brown, P.E., eds., Gold in 2000: Reviews in Nevada, in Coyner, A.R., and Fahey, P.L., eds., Geol- Remote Sensing of Environment, v. 99, p. 105–126, Economic Geology, v. 13, p. 163–220. ogy and ore deposits of the American Cordillera: Geo- doi: 10.1016/j.rse.2004.11.021. Hofstra, A.H., and Wallace, A.R., 2006, Metallogeny of logical Society of Nevada Symposium Proceedings, Salisbury, J.W., and D’Aria, D.M., 1992a, Emissivity of ter- the Great Basin; crustal evolution, fl uid fl ow, and ore Reno/Sparks, Nevada, April 1995: Reno, Geological restrial materials in the 8–14 µm atmospheric window: deposits: U.S. Geological Survey Open-File Report Society of Nevada, p. 1595–1621. Remote Sensing of Environment, v. 42, p. 83–106, doi: 2006–1280, 36 p., http://pubs.usgs.gov/of/2006/1280/. Miller, E.L., Holdsworth, B.K., Whiteford, W.B., and Rodgers, 10.1016/0034-4257(92)90092-X. Hofstra, A.H., Snee, L.W., Rye, R.O., Folger, H.W., Phin- D., 1984, Stratigraphy and structure of the Schoonover Salisbury, J.W., and D’Aria, D.M., 1992b, Infrared (8–14 isey, J.D., Loranger, R.J., Dahl, A.R., Naeser, C.W., Sequence, northeastern Nevada; implications for Paleo- µm) remote sensing of soil particle size: Remote Stein, H.J., and Lewchuk, M.T., 1999, Age constraints zoic plate-margin tectonics: Geological Society of Amer- Sensing of Environment, v. 42, p. 157–165, doi: on Jerritt Canyon and other Carlin-type gold deposits ica Bulletin, v. 95, p. 1063–1076, doi: 10.1130/0016- 10.1016/0034-4257(92)90099-6. in the western United States; relationship to mid-Ter- 7606(1984)95<1063:SASOTS>2.0.CO;2. Salisbury, J.W., Walter, L.S., Vergo, N., and D’Aria, D.M., tiary extension and magmatism: Economic Geology Mineral Resource Data System (MRDS), 2007, U.S. Geo- 1991, Infrared (2.1–25 micrometers) spectra of miner- and the Bulletin of the Society of Economic Geolo- logical Survey, http://mrdata.usgs.gov/. als: Baltimore, Maryland, and London, Johns Hopkins gists, v. 94, p. 769–802. Ninomiya, Y., Fu, B., and Cudahy, T.J., 2005, Detecting University Press, 267 p., see also ASTER Spectral Hook, S.J., Abbott, E.A., Grove, C., Kahle, A.B., and Pal- lithology with Advanced Spaceborne Thermal Emis- Library (http://speclib.jpl.nasa.gov/). luconi, F., 1999, Use of multispectral thermal infrared sion and Refl ection Radiometer (ASTER) multi- Schrader, F.C., 1923, The Jarbidge mining district, Nevada: data in geological studies, in Rencz, A.N., ed., Remote spectral thermal infrared “radiance-at-sensor” data: U.S. Geological Survey Bulletin 741, 86 p. sensing for the Earth sciences, Manual of remote sens- Remote Sensing of Environment, v. 99, p. 127–139, Sherlock, M.G., Cox, D.P., and Huber, D.F., 1996, Known ing, Volume 3 (third edition): New York, John Wiley doi: 10.1016/j.rse.2005.06.009. mineral deposits and occurrences in Nevada, in Singer, and Sons, Inc., p. 59–110. Nutt, C.J., 2000, Geologic map of the Alligator Ridge area, D.A., ed., An analysis of Nevada’s metal-bearing min- Hook, S.J., Myers, J.J., Thome, K.J., Fitzgerald, M., and including the Buck Mountain East and Mooney Basin eral resources: Nevada Bureau of Mines and Geology Kahle, A.B., 2001, The MODIS/ASTER airborne sim- Summit quadrangles and parts of the Sunshine Well Open-File Report 96–2, p. 10-1–10-37. ulator (MASTER)—A new instrument for earth sci- NE and Long Valley Slough quadrangles, White Pine Shevenell, L., and Garside, L.J., 2005, Nevada geothermal ence studies: Remote Sensing of Environment, v. 76, County, Nevada: U.S. Geological Survey Geologic resources (second edition): Nevada Bureau of Mines p. 93–102, doi: 10.1016/S0034-4257(00)00195-4. Investigations Series I-2691, scale 1:24000, http:// and Geology Map 141, scale 1:750,000. Hose, R.K., Blake, M.C., Jr., and Smith, R.M., 1976, Geol- greenwood.cr.usgs.gov/pub/i-maps/i-2691/. Sillitoe, R.H., and Lorson, R.C., 1994, Epithermal gold- ogy and mineral resources of White Pine County, Nutt, C.J., and Hart, K.S., 2004, Geologic map of the Big Bald silver-mercury deposits at Paradise Peak, Nevada; ore Nevada: Nevada Bureau of Mines and Geology Bul- Mountain Quadrangle and part of the Tognini Spring controls, porphyry gold association, detachment fault- letin 85, 105 p., scale 1:250,000. Quadrangle, White Pine County, Nevada: Nevada Bureau ing, and supergene oxidation: Economic Geology and John, D.A., 2001, Miocene and early Pliocene epithermal gold- of Mines and Geology, Map 145, 8 p., scale 1:24000, the Bulletin of the Society of Economic Geologists, silver deposits in the northern Great Basin, western United http://www.nbmg.unr.edu/dox/m145text.pdf and http:// v. 89, p. 1228–1248. States: Characteristics, distribution, and relationship to www.nbmg.unr.edu/dox/m145plate.pdf. Smith, J.F., and Ketner, K.B., 1978, Geologic map of the magmatism: Economic Geology and the Bulletin of the Nutt, C.J., and Hofstra, A.H., 2003, Alligator Ridge district, east- Carlin-Piñon Range area, Elko and Eureka Coun- Society of Economic Geologists, v. 96, p. 1827–1853. central Nevada: Carlin-type gold mineralization at shallow ties, Nevada: U.S. Geological Survey Miscellaneous John, D.A., Thomason, R.E., and McKee, E.H., 1989, Geol- depths: Economic Geology and the Bulletin of the Society Investigations Series Report I-1028, scale 1:62,500, ogy and K-Ar geochronology of the Paradise Peak of Economic Geologists, v. 98, p. 1225–1241. ftp://nas.library.unr.edu/keck/31901nvgeolmapmd/ Mine and the relationship of pre-Basin and Range Nutt, C.J., and Hofstra, A.H., 2007, Bald Mountain, Au min- usgs_mi1028.zip. extension to early Miocene precious-metal mineraliza- ing district: Economic Geology and the Bulletin of the Theodore, T.G., 1998, Large distal disseminated precious tion in west-central Nevada: Economic Geology and Society of Economic Geologists, v. 102, 6. metal deposits, Battle Mountain mining district, the Bulletin of the Society of Economic Geologists, Reheis, M., 1999, Extent of Pleistocene lakes in the Western Nevada: U.S. Geological Survey Open-File Report v. 84, p. 631–649. Great Basin: U.S. Geological Survey Miscellaneous 98–338, p. 253–258. Kirkland, L., Herr, K., Keim, E., Adams, P., Salisbury, J., Field Studies Map MF-2323, http://pubs.usgs.gov/ Theodore, T.G., 2000, Geology of pluton-related gold min- Hackwell, J., and Treiman, A., 2002, First use of an mf/1999/mf-2323/. eralization at Battle Mountain, Nevada: Monographs airborne thermal infrared hyperspectral scanner for Rockwell, B.W., 1991, Evaluation of GERIS airborne spec- in Mineral Resource Science 2: Tucson, University of compositional mapping: Remote Sensing of Envi- trometer data analysis for disseminated gold explora- Arizona Center for Mineral Resources, 271 p. ronment, v. 80, p. 447–459, doi: 10.1016/S0034- tion: A case study from the Getchell Trend/Potosi Vaughan, R.G., Hook, S.J., Calvin, W.M., and Taranik, J.V., 4257(01)00323-6. mining district, Nevada, USA, in Proceedings, Interna- 2005, Surface mineral mapping at Steamboat Springs, Kratt, C.B., 2005, Geothermal exploration with remote tional Symposium on Remote Sensing of Environment, Nevada, USA, with multi-wavelength thermal infra- sensing from 0.45–2.5 μm over Brady-Desert Peak, Eighth Thematic Conference: Geologic Remote Sens- red images: Remote Sensing of Environment, v. 99, Churchill County, Nevada [Master’s thesis]: Reno, ing: Denver, Colorado, USA, April 29–May 2, 1991: p. 140–158, doi: 10.1016/j.rse.2005.04.030. University of Nevada, 120 p. Ann Arbor, Michigan, ERIM. Wallace, A.R., Ludington, S., Mihalasky, M.J., Peters, S.G., Kruse, F.A., Lefkoff, A.B., Boardman, J.W., Heidebrecht, Rockwell, B.W., Clark, R.N., Cunningham, C.G., Sutley, S.J., Theodore, T.G., Ponce, D.A., John, D.A., Berger, B.R., K.B., Shapiro, A.T., Barloon, P.J., and Goetz, A.F.H., Gent, C., McDougal, R.R., Livo, K.E., and Kokaly, R.F., Zientek, M.L., Sidder, G.B., and Zierenberg, R.A., 1993, The Spectral Image Processing System (SIPS); 2000, Mineral mapping in the Marysvale volcanic fi eld, 2004, Assessment of metallic resources in the Hum- interactive visualization and analysis of imaging spec- Utah using AVIRIS data, in Green, R.O., ed., Summaries boldt River basin, northern Nevada, with a section on trometer data: Remote Sensing of Environment, v. 44, of the 9th Annual JPL Airborne Earth Science Workshop: platinum-group-elements (PGE) potential of the Hum- p. 145–163, doi: 10.1016/0034-4257(93)90013-N. NASA JPL Publication 00–18, p. 407–417, ftp://popo.jpl. boldt mafi c complex: U.S. Geological Survey Bulletin Lapointe, D.D., Tingley, J.V., and Jones, R.B., 1991, Mineral nasa.gov/pub/docs/workshops/00_docs/Rockwell_web. 2216, 1 CD-ROM. resources of Elko County, Nevada: Nevada Bureau of pdf and http://speclab.cr.usgs.gov/earth.studies/Utah-1/ Watson, D.F., 1992, Contouring: A guide to the analysis and Mines and Geology Bulletin 106, 236 p. marysvale_JPL2000_fi nal.pdf. display of spatial data: Computer Methods in the Geo- Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 2000, Sig- Rockwell, B.W., McDougal, R.R., and Gent, C.A., 2005, sciences, v. 10, 321 p. nifi cant deposits of gold, silver, copper, lead, and zinc in Remote sensing for environmental site screening and Wilkins, D.E., 2000, Changing modes of eolian sedimenta- the United States: Economic Geology and the Bulletin of watershed evaluation in Utah mine lands: East Tintic tion as an indicator of regional climate change; gypsum the Society of Economic Geologists, v. 95, p. 629–644. Mountains, Oquirrh Mountains, and Tushar Moun- and quartzose sands: Geological Society of America Lowe, N.T., 1985, Principal deposits of strategic and critical tains: U.S. Geological Survey Scientifi c Investiga- Abstracts with Programs, v. 32, no. 7, p. 22. minerals in Nevada: U.S. Department of the Interior, tions Report 2004–5241, 84 p., http://pubs.usgs.gov/ Bureau of Mines Information Circular 9035, 202 p. sir/2004/5241/ and http://speclab.cr.usgs.gov/earth. Ludington, S., Moring, B.C., Miller, R.J., Stone, P.A., studies/Utah-1/sir5241txto_bredit.html. MANUSCRIPT RECEIVED 30 APRIL 2007 Bookstrom, A.A., Bedford, D.R., Evans, J.G., Haxel, Rockwell, B.W., Cunningham, C.G., Breit, G.N., and Rye, REVISED MANUSCRIPT RECEIVED 20 SEPTEMBER 2007 G.A., Nutt, C.J., Flyn, K.S., and Hopkins, M.J., 2005, R.O., 2006, Spectroscopic mapping of the White Horse MANUSCRIPT ACCEPTED 2 OCTOBER 2007

246 Geosphere, February 2008

Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/4/1/218/3341029/i1553-040X-4-1-218.pdf by guest on 29 September 2021