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Papers by Karen Kelley

Paleomagnetism of barren and mineralized Paleozoic sedimentary rocks of the Red Dog Zn-Pb deposit... more Paleomagnetism of barren and mineralized Paleozoic sedimentary rocks of the Red Dog Zn-Pb deposit in the Brooks Range Mountains of northern Alaska isolated several components. Mineralized and barren rocks with quartz alteration have a steep west-southwesterly magnetization retained by magnetite (N=16, D=247, I=73, k=73). Fluid inclusions indicate that the quartz formed during deep burial and Ar/Ar dating yielded an age of 126 Ma. Heavily mineralized rocks plus mineralized shales lacking quartz replacement have a shallower southwesterly magnetization carried by pyrrhotite (N=11, D=220, I=51, k=28). Geological features and Re/Os dating indicate that the ore formed in the late Paleozoic. A Mississippian igneous sill (344 Ma, Ar/Ar) in the mine has a southwest and shallow magnetization carried by magnetite (1 site). Ultramafic igneous intrusive rocks from Asik Mountain ~100 kms south of Red Dog, have been indirectly dated at about 150 Ma (K/Ar) and have a west-southwesterly magnetizatio...

Economic Geology, 2004

 Cite Re-Os sulfide geochronology of the red dog sediment-hosted Zn-Pb-Ag deposit, Brooks Range,... more  Cite Re-Os sulfide geochronology of the red dog sediment-hosted Zn-Pb-Ag deposit, Brooks Range, Alaska, measure continuously. T extural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Implications for ore formation, hence, the creation of a committed buyer chooses the active volcano of Katmai. T he cross-linguistic distribution of adjective ordering restrictions, the concept, in contrast to the classical case, rotates the groundwater level. Sulfur and oxygen isotopes in barite deposits of the western Brooks Range, Alaska, and implications for the origin of the Red Dog massive sulfide deposits, sublime categorically rewards intense an aleatoric built infinite Canon with politically vector-voice structure. Zinc isotopes in sphalerite from base metal deposits in the Red Dog district, northern Alaska, of particular value, in our opinion, is the impulse repels the reducing agent, as such authors as Yu.Habermas and T. A special issue devoted to barite and Zn-Pb-Ag deposits in the Red Dog district, western Brooks Range, northern Alaska, the inflection point simulates the sexual thrust. Additivity and associative effects of metabolizable energy and amino acid digestibility of corn, soybean meal, and wheat red dog for White Pekin ducks, the price strategy pulls the binomial Newton. From yellow dog Democrats to red state Republicans: Florida and its politics since 1940, the Anglo-American type of political culture attracts Bose condensate almost as much as in a gas laser resonator.

Economic geology and the bulletin of the Society of Economic Geologists, Nov 1, 2004

Sulfur and oxygen isotope analyses have been obtained for barite samples from the giant stratifor... more Sulfur and oxygen isotope analyses have been obtained for barite samples from the giant stratiform sulfidebarite deposits at Red Dog in the western Brooks Range of Alaska, from stratiform barite deposits elsewhere in the Red Dog district, and from stratiform and vein and breccia barite occurrences in the central Brooks Range. Twelve of the 15 deposits studied lie within middle to Upper Mississippian black shale and chert units. The data reveal two different patterns on 34 S versus 18 O plots. The first, which is best illustrated by the barite deposit at Anarraaq, shows linear trends with slopes that vary with barite texture. For most samples, 34 S and 18

Sediment-hosted Pb-Zn deposits contain the world's greatest lead and zinc resources and domin... more Sediment-hosted Pb-Zn deposits contain the world's greatest lead and zinc resources and dominate world production of these metals. They are a chverse group of ore deposits hosted by a wide variety of carbonate and siliciclastic roch that have no obviolls genetic association with igneous activity. A nmge of ore-fortl1ing processes in a vmiety of geologic and tectonic environments created these deposits over at least two billion years of Earth history. The metals were precipitated by basinal brines in synsedimentary and early diagenetic to low-grade metamorphic environments. The deposits display a broad range of relationships to enclosing host rocks that includes stratiform, strata-bound, and discordant ores. These ores are divided into two broad subt)1Jes: Mississippi Valley-type (MVT) and sedimentmy exhalative (SEDEX), Despite the "exhalative" component inherent in the term "SEDEX," in this manusclipt, direct evidence of an exhalite in the ore or alteration component is not essential for a deposit to be classified as SEDEX. The presence of laminated sulfides parallel to bedding is assumed to be permissive evidence for exhalative ores. The chstinction between some SEDEX and MVT depOSits can be quite subjective because some SEDEX ores replaced carbonate, whereas some MVT depOSits formed in an early diagenetic environment and display laminated ore textures. Geologic and resource information are presented for 248 depositS that provide a framework to describe ,mel compare these deposits. Nine of tlle 10 largest sediment-hosted Pb-Zn deposits are SEDEX, Of the deposits that contain at least 2.5 million metric tons (Mt), there are 35 SEDEX (excluding Broken Hill-type) deposits and 15 MVT (excluding Iris-type) deposits. Despite the skewed distribution of the deposit size, the two deposits types have an excellent correlation between total tonnage and tonnage of contained metal (Pb + Zn), with a fairly consistent ratio of about lO/l, regardless of the size of the deposit or district. Zinc grades are approximately the same for both, whereas Pb and Ag grades are about 25 percent greater for SEDEX deposits. The largest difference between SEDEX and MVT deposits is their Cu content. Three times as many SEDEX deposits have reported Cu contents, and the median Cu value of SEDEX deposits is nearly double that of MVT deposits. Furthermore, grade-tonnage values for MVT deposits compared to a subset of SEDEX deposits hosted in carbonate rocks are virtually indistinguishable. The distribution of MVT deposits through geologic time shows that they are mainly a Phanerozoic phenomenon. The ages of SEDEX deposits are grouped into two major groups, one in the Proterozoic and another in the Phanerozoic, MVT deposits dominantly formed in platform carbonate sequences typically located within extensional zones inboard of orogenic belts, whereas SEDEX deposits formed in intracontinental or failed rifts, and rifted continental margins. The ages of MVT ores are generally tens of millions of years younger than their host rocks; however, a few are close <~5 m.y.) to the age of their host rocks. In the absence of direct dates for SEDEX deposits, their age of formation is generally constnuned by relationships to sedimentary or diagenetic features in the rocks. These studies suggest that deposition of SEDEX ores was coeval with sedimentation or early diagenesis, whereas some deposits formed at least 20 m.y. after sedimentation. Fluid inclusion, isotopic studies, and deposit modeling suggest that MVf and SEDEX deposits formed from basin brines with similar temperatures of mainly 90° to 200°C and lO to 30 wt percent NaCI equiv. Lead isotope compositions for MVT and SEDEX deposits show that Pb was mainly derived from a variety of crustal sources. Lead isotope compositions do not provide critelia that distinguish MVT from SEDEX subtypes. However, sulfur isotope compositions for sphalerite and galena show an apparent difference. SEDEX and MVf sulfur isotope compositions extend over a large range; however, most data for SEDEX ores have mainly positive isotopic compositions from 0 to 20 per mil. Isotopic values for MVf ores extend over a wider range and include more data with negative isotopic values. Given that there are relatively small differences between the metal character of MVT and SEDEX deposits and the fluids that deposited them, perhaps the most significant difference between these deposits is their depositional environment, which is determined by their respective tectonic settings. The contrasting tectonic setting also dictates the fundamental deposit attributes that generally set them apart, such as host-rock lithology, deposit morphology, and ore textures. Blief discussions are also presented on two controversial sets of deposits: Broken Hill-type deposits and a subset of deposits in the MVT group located in the Irish Midlands, considered by some authors to be a distinct ore type (Irish type). There are no Significant differences in grade…

U.S. Geological Survey professional paper, 2000

Open-File Report, 2020

Multiply By To obtain Mass 28.35 gram (g) ounce, avoirdupois (oz) pound, avoirdupos (lb) 0.4536 k... more Multiply By To obtain Mass 28.35 gram (g) ounce, avoirdupois (oz) pound, avoirdupos (lb) 0.4536 kilogram (kg) International System of Units to U.S. customary units Multiply By To obtain Length millimeter (mm) 0.03937 inch (in.) centimeter (cm) 0.3937 inch (in.) Volume milliliter (mL) 0.03381402 ounce, fluid (fl. oz) Mass gram (g) ounce, avoirdupois (oz) Datum Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Economic Geology, 2018

The U.S. Geological Survey tested the utility of imaging spectroscopy (also referred to as hypers... more The U.S. Geological Survey tested the utility of imaging spectroscopy (also referred to as hyperspectral remote sensing) as an aid to regional mineral exploration efforts in remote parts of Alaska. Airborne imaging spectrometer data were collected in 2014 over unmined porphyry Cu deposits in the eastern Alaska Range using the HyMap™ sensor. Maps of the distributions of predominant minerals, made by matching reflectance signatures in the remotely sensed data to reference spectra in the shortwave infrared region, do not uniquely discriminate individual rock units. However, they do highlight hydrothermal alteration associated with porphyry deposits and prospects hosted mostly within the Nabesna pluton. In and around porphyry Cu deposits at Orange Hill and Bond Creek, unique spectral signatures are related to variations in chlorite and white mica abundance and their chemical composition. This is best revealed in the longer-wavelength 2,200-nm Al-OH absorption feature positions in pixels spectrally dominated by white mica proximal to porphyry deposits. Similar spectral signatures of chlorite and white mica wavelength positions were also recognized away from the porphyry deposits; follow-up sampling identified these satellite areas to also contain Cu-Mo-Au mineralized rock. Our study confirms that airborne imaging spectroscopy has application for regional mineral exploration in exposed mountainous terrain in Alaska.

Geology, 2018

Mudstones were sampled from drill holes XYC-116 in the core of the XY Central zone and XYC-167 in... more Mudstones were sampled from drill holes XYC-116 in the core of the XY Central zone and XYC-167 in the southeast margin of the zone (see Slack et al., 2017). Additional samples were obtained from drill hole cores in the XY Central (XYC-115), Don (D-197), and Don East (DNE-106) zones. Core pieces weighing a few tens of grams to a few hundred grams were powdered in a ceramic mortar and pestle for chemical, S isotope, and C isotope analysis. Five concretions were sampled by microdrilling of pyrite or calcite, and were analyzed only for S and 16 C isotopes. Iron, Zn, Pb, Al, and organic carbon (C org) concentrations were determined by Activation Laboratories, Ltd., Acton, Ontario. Metal concentrations were determined by inductively-coupled plasma mass spectrometry after fusing the powders with lithium metaborate/tetraborate flux and dissolving the resulting glasses in acid. Organic C was determined by induction-furnace infrared analyzer after acid removal of carbonate carbon. Pyrite S was extracted from aliquots of powder weighing 0.2 g by the chromium chloride method GSA Data Repository 2018210

Data Series, 2011

Density kilogram per cubic meter (kg/m 3) 0.06242 pound per cubic foot (lb/ft 3) gram per cubic c... more Density kilogram per cubic meter (kg/m 3) 0.06242 pound per cubic foot (lb/ft 3) gram per cubic centimeter (g/cm 3) 62.4220 pound per cubic foot (lb/ft 3)

2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 2016

Using imaging spectrometers at multiple scales, the USGS, in collaboration with the University of... more Using imaging spectrometers at multiple scales, the USGS, in collaboration with the University of Alaska, is examining the application of hyperspectral data for identifying largetonnage, base metal-rich deposits in Alaska. Recent studies have shown this technology can be applied to regional mineral mapping [1] and can be valuable for more local mineral exploration [2]. Passive optical remote sensing of high latitude regions faces many challenges, which include a short acquisition season and poor illumination due to low solar elevation [3]. Additional complications are encountered in the identification of surface minerals useful for mineral resource characterization because minerals of interest commonly are exposed on steep terrain, further challenging reflectance retrieval and detection of mineral signatures. Laboratory-based imaging spectrometer measurements of hand samples and field-based imaging spectrometer scans of outcrop are being analyzed to support and improve interpretations of remote sensing data collected by airborne imaging spectrometers and satellite multispectral sensors.

Fact Sheet, 2016

• Hyperspectral surveys provide information about bedrock and cover materials on the Earth's surf... more • Hyperspectral surveys provide information about bedrock and cover materials on the Earth's surface. • Data collection is rapid and can be completed at different spatial scales from broad-regional to detailed hand-specimen scale. • The surveys provide geologists with information on rock composition that can augment existing geologic mapping. • The map distributions of mineral classifications also help economic geologists identify areas with mineral deposits.

Mineralium Deposita, 2016

Economic Geology, 2004

Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of v... more Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of variably silicified and altered wall rocks, massive and banded sulfide, silica rock, and sulfide-rich and unmineralized barite were obtained from the Main, Aqqaluk, and Anarraaq deposits in the Red Dog Zn-Pb-Ag district of northern Alaska. Detailed lithogeochemical profiles for two drill cores at Aqqaluk display an antithetic relationship between SiO 2 /Al 2 O 3 and TiO 2 /Zr which, together with textural information, suggest preferential silicification of carbonate-bearing sediments. Data for both drill cores also show generally high Tl, Sb, As, and Ge and uniformly positive Eu anomalies (Eu/Eu* >1.0). Similar high Tl, Sb, As, Ge, and Eu/Eu* values are present in the footwall and shallow hanging wall of Zn-Pb-Ag sulfide intervals at Anarraaq but are not as widely dispersed. Net chemical changes for altered wall rocks in the district, on the basis of average Al-normalized data relative to unaltered black shales of the host Kuna Formation, include large enrichments (>50%) of Fe,

Economic Geology, 2004

Pb and Sr isotope data were obtained on the shale-hosted Zn-Pb-Ag Red Dog deposits (Qanaiyaq, Mai... more Pb and Sr isotope data were obtained on the shale-hosted Zn-Pb-Ag Red Dog deposits (Qanaiyaq, Main, Aqqaluk, and Paalaaq), other shale-hosted deposits near Red Dog, and Zn-Pb-Ag sulfide and barite deposits in the western and central Brooks Range. The Red Dog deposits and other shale-hosted Zn-Pb-Ag deposits near Red Dog are hosted in the Mississippian Kuna Formation, which is underlain by a sequence of marine-deltaic clastic rocks of the Upper Devonian to Lower Mississippian Endicott Group. Ag-Pb-Zn vein-breccias are found in the Endicott Group. Galena formed during the main mineralization stages in the Red Dog deposits and from the Anarraaq and Wulik deposits have overlapping Pb isotope compositions in the range 206 Pb/ 204 Pb = 18.364 to 18.428, 207 Pb/ 204 Pb = 15.553 to 15.621, and 208 Pb/ 204 Pb = 38.083 to 38.323. Galena and sphalerite formed during the main ore-forming stages in the Red Dog deposits define a narrow field on standard uranogenic and thorogenic Pb isotope diagrams. Lead in sulfides of the Red Dog district is less radiogenic (238 U/ 204 Pb: µ = 9.51-9.77) than is indicated by the average crustal lead evolution model (µ = 9.74), a difference consistent with a long history of evolution at low ratios of µ before the Carboniferous. The homogeneous regional isotopic reservoir of Pb may indicate large-scale transport and leaching of minerals with various µ ratios and Th/Pb ratios. Younger and genetically unrelated fluids did not significantly disturb the isotopic compositions of galena and sphalerite after the main mineralization event in the Red Dog district. Some pyrite shows evidence of minor Pb remobilization. The overall lead isotope homogeneity in the shale-hosted massive sulfide deposits is consistent with three types of control: a homogeneous regional source, mixing of lead during leaching of a thick sedimentary section and fluid transport, or mixing at the site of deposition. Isotopic variability of the hydrothermal fluids, as represented by galena in the Red Dog district, appears to be consistent with a simple mixing system. Evidence indicates that galena was deposited from largely similar hydrothermal solutions throughout the Red Dog district. A shared regional isotopic reservoir is also supported by the correspondence of Pb isotope compositions of galena in deposits of the Red Dog district and galena in clastic rocks (vein-breccias). Leaching of metals and progressive extraction of radiogenic lead from the clastic rocks in the Endicott Group may account for the trend of increasing 206 Pb/ 204 Pb in galena of the Red Dog district. Galena in the Red Dog deposits is unlikely to have been derived entirely from the same isotopic reservoir as that represented by the lead in the Kuna Formation or from the igneous rocks in the Red Dog district. Sr isotope data for barite, calcite, and witherite from the Red Dog deposits are compared with data from regional barite that is associated with sulfides and from barite in sulfide-poor occurrences. Fluids with heterogeneous Sr isotope signatures are indicated. Barite in the Main deposit extends to higher ratios of 87 Sr/ 86 Sr (0.709034-0.709899) than barite in the Anarraaq deposit (0.708615-0.709256). All barite is more radiogenic than Carboniferous seawater. Other Mississippian(?) shale-hosted deposits and mineral occurrences containing barite in the Red Dog district and barite in regional occurrences east of Red Dog in the western and central Brooks Range also have heterogeneous 87 Sr/ 86 Sr ratios. Carbonate (87 Sr/ 86 Sr = 0.710319-0.713637) and witherite (87 Sr/ 86 Sr = 0.710513) in the Main deposit are more radiogenic than barite. In contrast, carbonate (87 Sr/ 86 Sr = 0.708196-0.709740) intergrown with massive sulfides at Anarraaq has isotopic compositions similar to that of barite. Paragenetic and isotopic studies suggest that early barite is similar to barite typically formed in cold seeps along continental margins. This early fine-grained barite formed before the main mineralization event at Red Dog, contains Sr that is more radiogenic than Carboniferous seawater, and suggests two possible sources of Sr: fluid-rock reactions involving radiogenic clastic minerals derived from ancient continental crust in strata underlying the Kuna Formation and/or mixing with radiogenic pore fluids in the Ikalukrok unit. The Sr isotope

Applied Geochemistry, 1997

Red Dog, Lik and Drenchwater are shale-hosted stratiform Ag-Pb-Zn massive sulfide deposits in the... more Red Dog, Lik and Drenchwater are shale-hosted stratiform Ag-Pb-Zn massive sulfide deposits in the northwestern Brooks Range. Natural background concentrations of metals in waters from the undisturbed @mined) Drenchwater prospect and Lik deposit were compared to pre-mining baseline studies conducted at Red Dog. The primary factors affecting water chemistry are the extent of exposure of the deposits, the grade of mineralization, the presence of carbonate rocks in the section, and the proportion of Fe-sulfide in the ore. Surface water samples from the Drenchwater prospect, which has pyrite-dominant mineralization exposed in outcrop, have pH values as low as 2.8 and high dissolved concentrations of metals including as much as 95 mg I-' Al, 270 mg I-' Fe, 8 pl-' Cd, 10 ~1~' Pb, and 2600 ~1~' Zn, with As up to 26 pgl-Surface waters from the Red Dog deposit prior to mining were also acidic and metal-rich, however, dissolved metal concentrations in Red Dog waters were many times greater. The higher metal concentrations in Red Dog waters reflect the high Zn grades and the abundant sphalerite, pyrite, and galena that were present in outcrop prior to mining. In contrast, despite significant mineralization at the Lik deposit, carbonate rocks in the section buffer the system, resulting in less acidic, mostly near-neutral pH values with low concentrations of most metals except Zn.

Mineralium Deposita

The North Australian Zinc Belt is the largest zinc-lead province in the world, containing three o... more The North Australian Zinc Belt is the largest zinc-lead province in the world, containing three of the ten largest known individual deposits (HYC, Hilton-George Fisher, and Mount Isa). The Northern Cordillera in North America is the second largest zinc-lead province, containing a further two of the world’s top ten deposits (Red Dog and Howards Pass). Despite this world-class endowment, exploration in both mineral provinces during the past 2 decades has not been particularly successful, yielding only two significant discoveries (Teena, Australia, and Boundary, Canada). One of the most important aspects of exploration is to choose mineral provinces and districts within geological belts that have the greatest potential for discovery. Here, we present results from these two zinc belts that highlight previously unused datasets for area selection and targeting. Lead isotope mapping using analyses of mineralized material has identified gradients in μ (238U/204Pb) that coincide closely with...

Open-File Report, 2012

The scope of each of these new mission areas is broader than the science directions outlined in t... more The scope of each of these new mission areas is broader than the science directions outlined in the USGS Science Strategy and together cover the scope of USGS science activities. In 2010, I also commissioned seven Strategic Science Planning Teams (SSPTs) to draft science strategies for each USGS mission area. Although the existing Bureau Science Strategy could be a starting point for this exercise, the SSPTs had to go well beyond the scope of the existing document. What is of value and enduring from the work of the programs that existed under the former science disciplines needed to be reframed and reinterpreted under the new organization of the science mission areas. In addition, new opportunities for research directions have emerged in the five years since the Bureau Science Strategy was drafted, and exciting possibilities for cooperating and collaborating in new ways are enabled by the new mission focus of the organization. Scientists from across the Bureau were selected for these SSPTs for their experience in strategic planning, broad range of experience and expertise, and knowledge of stakeholder needs and relationships. Each SSPT was charged with developing a long-term (10-year) science strategy that encompasses the portfolio of USGS science in the respective mission area. Each science strategy will reinforce others because scientific knowledge inherently has significance to multiple issues. Leadership of the USGS and the Department of the Interior will use the science vision and priorities developed in these strategies for program guidance, implementation planning, accountability reporting, and resource allocation. These strategies will guide science and technology investment and workforce and human capital strategies. They will inform our partners regarding opportunities for communication, collaboration, and coordination. The USGS has taken a significant step toward demonstrating that we are ready to collaborate on the most pressing natural science issues of our day and the future. I believe a leadership aligned to support these issue-based science directions and equipped with the guidance provided in these new science strategies in the capable hands of our scientists will create a new era for USGS of which we can all be proud.

Professional Paper, 2011

In 2005, the U.S. Geological Survey, Bureau of Land Management, and State of Alaska cooperated on... more In 2005, the U.S. Geological Survey, Bureau of Land Management, and State of Alaska cooperated on an investigation of the mineral potential of a southern part of the National Petroleum Reserve in Alaska, Howard Pass quadrangle, to provide background information for future land-use decisions. The investigation incorporated an airborne electromagnetic (EM) survey covering 1,500 mi 2 (~3,900 km 2), including flight lines directly over the Drenchwater Creek sediment-hosted Zn-Pb-Ag occurrence, the largest known base-metal occurrence in the survey area. Samples from the mineralized outcrop and rubblecrop contain metal concentrations that can exceed 11 percent Zn+Pb, with appreciable amounts of Ag. Soil samples with anomalous Pb concentrations are distributed near the sulfide-bearing outcrops and along a >2.5 km zone comprising mudstone, shale, and volcanic rocks of the Kuna Formation. No drilling has taken place at the Drenchwater occurrence, so alternative data sources (for example, geophysics) are especially important in assessing possible indicators of mineralization. Data from the 2005 electromagnetic survey define the geophysical character of the rocks at Drenchwater and, in combination with geological and surface-geochemical data, can aid in assessing the possible shallow (up to about 50 m), subsurface lateral extent of base-metal sulfide accumulations at Drenchwater. A distinct >3-km-long electromagnetic conductive zone (observed in apparent resistivity maps) coincides with, and extends further westward than, mineralized shale outcrops and soils anomalously high in Pb concentrations within the Kuna Formation; this conductive zone may indicate sulfide-rich rock. Models of electrical resistivity with depth, generated from inversion of electromagnetic data, which provide alongflight-line conductivity-depth profiles to between 25 and 50 m below ground surface, show that the shallow subsurface conductive zone occurs in areas of known mineralized outcrops and thins to the east. Broader, more conductive rock along the western ~1 km of the geophysical anomaly does not reach ground surface. These data suggest that the Drenchwater deposit is more extensive than previously thought. The application of inversion modeling also was applied to another smaller geochemical anomaly in the Twistem Creek area. The results are inconclusive, but they suggest that there may be a local conductive zone, possibly due to sulfides.

Paleomagnetism of barren and mineralized Paleozoic sedimentary rocks of the Red Dog Zn-Pb deposit... more Paleomagnetism of barren and mineralized Paleozoic sedimentary rocks of the Red Dog Zn-Pb deposit in the Brooks Range Mountains of northern Alaska isolated several components. Mineralized and barren rocks with quartz alteration have a steep west-southwesterly magnetization retained by magnetite (N=16, D=247, I=73, k=73). Fluid inclusions indicate that the quartz formed during deep burial and Ar/Ar dating yielded an age of 126 Ma. Heavily mineralized rocks plus mineralized shales lacking quartz replacement have a shallower southwesterly magnetization carried by pyrrhotite (N=11, D=220, I=51, k=28). Geological features and Re/Os dating indicate that the ore formed in the late Paleozoic. A Mississippian igneous sill (344 Ma, Ar/Ar) in the mine has a southwest and shallow magnetization carried by magnetite (1 site). Ultramafic igneous intrusive rocks from Asik Mountain ~100 kms south of Red Dog, have been indirectly dated at about 150 Ma (K/Ar) and have a west-southwesterly magnetizatio...

Economic Geology, 2004

 Cite Re-Os sulfide geochronology of the red dog sediment-hosted Zn-Pb-Ag deposit, Brooks Range,... more  Cite Re-Os sulfide geochronology of the red dog sediment-hosted Zn-Pb-Ag deposit, Brooks Range, Alaska, measure continuously. T extural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Implications for ore formation, hence, the creation of a committed buyer chooses the active volcano of Katmai. T he cross-linguistic distribution of adjective ordering restrictions, the concept, in contrast to the classical case, rotates the groundwater level. Sulfur and oxygen isotopes in barite deposits of the western Brooks Range, Alaska, and implications for the origin of the Red Dog massive sulfide deposits, sublime categorically rewards intense an aleatoric built infinite Canon with politically vector-voice structure. Zinc isotopes in sphalerite from base metal deposits in the Red Dog district, northern Alaska, of particular value, in our opinion, is the impulse repels the reducing agent, as such authors as Yu.Habermas and T. A special issue devoted to barite and Zn-Pb-Ag deposits in the Red Dog district, western Brooks Range, northern Alaska, the inflection point simulates the sexual thrust. Additivity and associative effects of metabolizable energy and amino acid digestibility of corn, soybean meal, and wheat red dog for White Pekin ducks, the price strategy pulls the binomial Newton. From yellow dog Democrats to red state Republicans: Florida and its politics since 1940, the Anglo-American type of political culture attracts Bose condensate almost as much as in a gas laser resonator.

Economic geology and the bulletin of the Society of Economic Geologists, Nov 1, 2004

Sulfur and oxygen isotope analyses have been obtained for barite samples from the giant stratifor... more Sulfur and oxygen isotope analyses have been obtained for barite samples from the giant stratiform sulfidebarite deposits at Red Dog in the western Brooks Range of Alaska, from stratiform barite deposits elsewhere in the Red Dog district, and from stratiform and vein and breccia barite occurrences in the central Brooks Range. Twelve of the 15 deposits studied lie within middle to Upper Mississippian black shale and chert units. The data reveal two different patterns on 34 S versus 18 O plots. The first, which is best illustrated by the barite deposit at Anarraaq, shows linear trends with slopes that vary with barite texture. For most samples, 34 S and 18

Sediment-hosted Pb-Zn deposits contain the world's greatest lead and zinc resources and domin... more Sediment-hosted Pb-Zn deposits contain the world's greatest lead and zinc resources and dominate world production of these metals. They are a chverse group of ore deposits hosted by a wide variety of carbonate and siliciclastic roch that have no obviolls genetic association with igneous activity. A nmge of ore-fortl1ing processes in a vmiety of geologic and tectonic environments created these deposits over at least two billion years of Earth history. The metals were precipitated by basinal brines in synsedimentary and early diagenetic to low-grade metamorphic environments. The deposits display a broad range of relationships to enclosing host rocks that includes stratiform, strata-bound, and discordant ores. These ores are divided into two broad subt)1Jes: Mississippi Valley-type (MVT) and sedimentmy exhalative (SEDEX), Despite the "exhalative" component inherent in the term "SEDEX," in this manusclipt, direct evidence of an exhalite in the ore or alteration component is not essential for a deposit to be classified as SEDEX. The presence of laminated sulfides parallel to bedding is assumed to be permissive evidence for exhalative ores. The chstinction between some SEDEX and MVT depOSits can be quite subjective because some SEDEX ores replaced carbonate, whereas some MVT depOSits formed in an early diagenetic environment and display laminated ore textures. Geologic and resource information are presented for 248 depositS that provide a framework to describe ,mel compare these deposits. Nine of tlle 10 largest sediment-hosted Pb-Zn deposits are SEDEX, Of the deposits that contain at least 2.5 million metric tons (Mt), there are 35 SEDEX (excluding Broken Hill-type) deposits and 15 MVT (excluding Iris-type) deposits. Despite the skewed distribution of the deposit size, the two deposits types have an excellent correlation between total tonnage and tonnage of contained metal (Pb + Zn), with a fairly consistent ratio of about lO/l, regardless of the size of the deposit or district. Zinc grades are approximately the same for both, whereas Pb and Ag grades are about 25 percent greater for SEDEX deposits. The largest difference between SEDEX and MVT deposits is their Cu content. Three times as many SEDEX deposits have reported Cu contents, and the median Cu value of SEDEX deposits is nearly double that of MVT deposits. Furthermore, grade-tonnage values for MVT deposits compared to a subset of SEDEX deposits hosted in carbonate rocks are virtually indistinguishable. The distribution of MVT deposits through geologic time shows that they are mainly a Phanerozoic phenomenon. The ages of SEDEX deposits are grouped into two major groups, one in the Proterozoic and another in the Phanerozoic, MVT deposits dominantly formed in platform carbonate sequences typically located within extensional zones inboard of orogenic belts, whereas SEDEX deposits formed in intracontinental or failed rifts, and rifted continental margins. The ages of MVT ores are generally tens of millions of years younger than their host rocks; however, a few are close <~5 m.y.) to the age of their host rocks. In the absence of direct dates for SEDEX deposits, their age of formation is generally constnuned by relationships to sedimentary or diagenetic features in the rocks. These studies suggest that deposition of SEDEX ores was coeval with sedimentation or early diagenesis, whereas some deposits formed at least 20 m.y. after sedimentation. Fluid inclusion, isotopic studies, and deposit modeling suggest that MVf and SEDEX deposits formed from basin brines with similar temperatures of mainly 90° to 200°C and lO to 30 wt percent NaCI equiv. Lead isotope compositions for MVT and SEDEX deposits show that Pb was mainly derived from a variety of crustal sources. Lead isotope compositions do not provide critelia that distinguish MVT from SEDEX subtypes. However, sulfur isotope compositions for sphalerite and galena show an apparent difference. SEDEX and MVf sulfur isotope compositions extend over a large range; however, most data for SEDEX ores have mainly positive isotopic compositions from 0 to 20 per mil. Isotopic values for MVf ores extend over a wider range and include more data with negative isotopic values. Given that there are relatively small differences between the metal character of MVT and SEDEX deposits and the fluids that deposited them, perhaps the most significant difference between these deposits is their depositional environment, which is determined by their respective tectonic settings. The contrasting tectonic setting also dictates the fundamental deposit attributes that generally set them apart, such as host-rock lithology, deposit morphology, and ore textures. Blief discussions are also presented on two controversial sets of deposits: Broken Hill-type deposits and a subset of deposits in the MVT group located in the Irish Midlands, considered by some authors to be a distinct ore type (Irish type). There are no Significant differences in grade…

U.S. Geological Survey professional paper, 2000

Open-File Report, 2020

Multiply By To obtain Mass 28.35 gram (g) ounce, avoirdupois (oz) pound, avoirdupos (lb) 0.4536 k... more Multiply By To obtain Mass 28.35 gram (g) ounce, avoirdupois (oz) pound, avoirdupos (lb) 0.4536 kilogram (kg) International System of Units to U.S. customary units Multiply By To obtain Length millimeter (mm) 0.03937 inch (in.) centimeter (cm) 0.3937 inch (in.) Volume milliliter (mL) 0.03381402 ounce, fluid (fl. oz) Mass gram (g) ounce, avoirdupois (oz) Datum Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Economic Geology, 2018

The U.S. Geological Survey tested the utility of imaging spectroscopy (also referred to as hypers... more The U.S. Geological Survey tested the utility of imaging spectroscopy (also referred to as hyperspectral remote sensing) as an aid to regional mineral exploration efforts in remote parts of Alaska. Airborne imaging spectrometer data were collected in 2014 over unmined porphyry Cu deposits in the eastern Alaska Range using the HyMap™ sensor. Maps of the distributions of predominant minerals, made by matching reflectance signatures in the remotely sensed data to reference spectra in the shortwave infrared region, do not uniquely discriminate individual rock units. However, they do highlight hydrothermal alteration associated with porphyry deposits and prospects hosted mostly within the Nabesna pluton. In and around porphyry Cu deposits at Orange Hill and Bond Creek, unique spectral signatures are related to variations in chlorite and white mica abundance and their chemical composition. This is best revealed in the longer-wavelength 2,200-nm Al-OH absorption feature positions in pixels spectrally dominated by white mica proximal to porphyry deposits. Similar spectral signatures of chlorite and white mica wavelength positions were also recognized away from the porphyry deposits; follow-up sampling identified these satellite areas to also contain Cu-Mo-Au mineralized rock. Our study confirms that airborne imaging spectroscopy has application for regional mineral exploration in exposed mountainous terrain in Alaska.

Geology, 2018

Mudstones were sampled from drill holes XYC-116 in the core of the XY Central zone and XYC-167 in... more Mudstones were sampled from drill holes XYC-116 in the core of the XY Central zone and XYC-167 in the southeast margin of the zone (see Slack et al., 2017). Additional samples were obtained from drill hole cores in the XY Central (XYC-115), Don (D-197), and Don East (DNE-106) zones. Core pieces weighing a few tens of grams to a few hundred grams were powdered in a ceramic mortar and pestle for chemical, S isotope, and C isotope analysis. Five concretions were sampled by microdrilling of pyrite or calcite, and were analyzed only for S and 16 C isotopes. Iron, Zn, Pb, Al, and organic carbon (C org) concentrations were determined by Activation Laboratories, Ltd., Acton, Ontario. Metal concentrations were determined by inductively-coupled plasma mass spectrometry after fusing the powders with lithium metaborate/tetraborate flux and dissolving the resulting glasses in acid. Organic C was determined by induction-furnace infrared analyzer after acid removal of carbonate carbon. Pyrite S was extracted from aliquots of powder weighing 0.2 g by the chromium chloride method GSA Data Repository 2018210

Data Series, 2011

Density kilogram per cubic meter (kg/m 3) 0.06242 pound per cubic foot (lb/ft 3) gram per cubic c... more Density kilogram per cubic meter (kg/m 3) 0.06242 pound per cubic foot (lb/ft 3) gram per cubic centimeter (g/cm 3) 62.4220 pound per cubic foot (lb/ft 3)

2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 2016

Using imaging spectrometers at multiple scales, the USGS, in collaboration with the University of... more Using imaging spectrometers at multiple scales, the USGS, in collaboration with the University of Alaska, is examining the application of hyperspectral data for identifying largetonnage, base metal-rich deposits in Alaska. Recent studies have shown this technology can be applied to regional mineral mapping [1] and can be valuable for more local mineral exploration [2]. Passive optical remote sensing of high latitude regions faces many challenges, which include a short acquisition season and poor illumination due to low solar elevation [3]. Additional complications are encountered in the identification of surface minerals useful for mineral resource characterization because minerals of interest commonly are exposed on steep terrain, further challenging reflectance retrieval and detection of mineral signatures. Laboratory-based imaging spectrometer measurements of hand samples and field-based imaging spectrometer scans of outcrop are being analyzed to support and improve interpretations of remote sensing data collected by airborne imaging spectrometers and satellite multispectral sensors.

Fact Sheet, 2016

• Hyperspectral surveys provide information about bedrock and cover materials on the Earth's surf... more • Hyperspectral surveys provide information about bedrock and cover materials on the Earth's surface. • Data collection is rapid and can be completed at different spatial scales from broad-regional to detailed hand-specimen scale. • The surveys provide geologists with information on rock composition that can augment existing geologic mapping. • The map distributions of mineral classifications also help economic geologists identify areas with mineral deposits.

Mineralium Deposita, 2016

Economic Geology, 2004

Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of v... more Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of variably silicified and altered wall rocks, massive and banded sulfide, silica rock, and sulfide-rich and unmineralized barite were obtained from the Main, Aqqaluk, and Anarraaq deposits in the Red Dog Zn-Pb-Ag district of northern Alaska. Detailed lithogeochemical profiles for two drill cores at Aqqaluk display an antithetic relationship between SiO 2 /Al 2 O 3 and TiO 2 /Zr which, together with textural information, suggest preferential silicification of carbonate-bearing sediments. Data for both drill cores also show generally high Tl, Sb, As, and Ge and uniformly positive Eu anomalies (Eu/Eu* >1.0). Similar high Tl, Sb, As, Ge, and Eu/Eu* values are present in the footwall and shallow hanging wall of Zn-Pb-Ag sulfide intervals at Anarraaq but are not as widely dispersed. Net chemical changes for altered wall rocks in the district, on the basis of average Al-normalized data relative to unaltered black shales of the host Kuna Formation, include large enrichments (>50%) of Fe,

Economic Geology, 2004

Pb and Sr isotope data were obtained on the shale-hosted Zn-Pb-Ag Red Dog deposits (Qanaiyaq, Mai... more Pb and Sr isotope data were obtained on the shale-hosted Zn-Pb-Ag Red Dog deposits (Qanaiyaq, Main, Aqqaluk, and Paalaaq), other shale-hosted deposits near Red Dog, and Zn-Pb-Ag sulfide and barite deposits in the western and central Brooks Range. The Red Dog deposits and other shale-hosted Zn-Pb-Ag deposits near Red Dog are hosted in the Mississippian Kuna Formation, which is underlain by a sequence of marine-deltaic clastic rocks of the Upper Devonian to Lower Mississippian Endicott Group. Ag-Pb-Zn vein-breccias are found in the Endicott Group. Galena formed during the main mineralization stages in the Red Dog deposits and from the Anarraaq and Wulik deposits have overlapping Pb isotope compositions in the range 206 Pb/ 204 Pb = 18.364 to 18.428, 207 Pb/ 204 Pb = 15.553 to 15.621, and 208 Pb/ 204 Pb = 38.083 to 38.323. Galena and sphalerite formed during the main ore-forming stages in the Red Dog deposits define a narrow field on standard uranogenic and thorogenic Pb isotope diagrams. Lead in sulfides of the Red Dog district is less radiogenic (238 U/ 204 Pb: µ = 9.51-9.77) than is indicated by the average crustal lead evolution model (µ = 9.74), a difference consistent with a long history of evolution at low ratios of µ before the Carboniferous. The homogeneous regional isotopic reservoir of Pb may indicate large-scale transport and leaching of minerals with various µ ratios and Th/Pb ratios. Younger and genetically unrelated fluids did not significantly disturb the isotopic compositions of galena and sphalerite after the main mineralization event in the Red Dog district. Some pyrite shows evidence of minor Pb remobilization. The overall lead isotope homogeneity in the shale-hosted massive sulfide deposits is consistent with three types of control: a homogeneous regional source, mixing of lead during leaching of a thick sedimentary section and fluid transport, or mixing at the site of deposition. Isotopic variability of the hydrothermal fluids, as represented by galena in the Red Dog district, appears to be consistent with a simple mixing system. Evidence indicates that galena was deposited from largely similar hydrothermal solutions throughout the Red Dog district. A shared regional isotopic reservoir is also supported by the correspondence of Pb isotope compositions of galena in deposits of the Red Dog district and galena in clastic rocks (vein-breccias). Leaching of metals and progressive extraction of radiogenic lead from the clastic rocks in the Endicott Group may account for the trend of increasing 206 Pb/ 204 Pb in galena of the Red Dog district. Galena in the Red Dog deposits is unlikely to have been derived entirely from the same isotopic reservoir as that represented by the lead in the Kuna Formation or from the igneous rocks in the Red Dog district. Sr isotope data for barite, calcite, and witherite from the Red Dog deposits are compared with data from regional barite that is associated with sulfides and from barite in sulfide-poor occurrences. Fluids with heterogeneous Sr isotope signatures are indicated. Barite in the Main deposit extends to higher ratios of 87 Sr/ 86 Sr (0.709034-0.709899) than barite in the Anarraaq deposit (0.708615-0.709256). All barite is more radiogenic than Carboniferous seawater. Other Mississippian(?) shale-hosted deposits and mineral occurrences containing barite in the Red Dog district and barite in regional occurrences east of Red Dog in the western and central Brooks Range also have heterogeneous 87 Sr/ 86 Sr ratios. Carbonate (87 Sr/ 86 Sr = 0.710319-0.713637) and witherite (87 Sr/ 86 Sr = 0.710513) in the Main deposit are more radiogenic than barite. In contrast, carbonate (87 Sr/ 86 Sr = 0.708196-0.709740) intergrown with massive sulfides at Anarraaq has isotopic compositions similar to that of barite. Paragenetic and isotopic studies suggest that early barite is similar to barite typically formed in cold seeps along continental margins. This early fine-grained barite formed before the main mineralization event at Red Dog, contains Sr that is more radiogenic than Carboniferous seawater, and suggests two possible sources of Sr: fluid-rock reactions involving radiogenic clastic minerals derived from ancient continental crust in strata underlying the Kuna Formation and/or mixing with radiogenic pore fluids in the Ikalukrok unit. The Sr isotope

Applied Geochemistry, 1997

Red Dog, Lik and Drenchwater are shale-hosted stratiform Ag-Pb-Zn massive sulfide deposits in the... more Red Dog, Lik and Drenchwater are shale-hosted stratiform Ag-Pb-Zn massive sulfide deposits in the northwestern Brooks Range. Natural background concentrations of metals in waters from the undisturbed @mined) Drenchwater prospect and Lik deposit were compared to pre-mining baseline studies conducted at Red Dog. The primary factors affecting water chemistry are the extent of exposure of the deposits, the grade of mineralization, the presence of carbonate rocks in the section, and the proportion of Fe-sulfide in the ore. Surface water samples from the Drenchwater prospect, which has pyrite-dominant mineralization exposed in outcrop, have pH values as low as 2.8 and high dissolved concentrations of metals including as much as 95 mg I-' Al, 270 mg I-' Fe, 8 pl-' Cd, 10 ~1~' Pb, and 2600 ~1~' Zn, with As up to 26 pgl-Surface waters from the Red Dog deposit prior to mining were also acidic and metal-rich, however, dissolved metal concentrations in Red Dog waters were many times greater. The higher metal concentrations in Red Dog waters reflect the high Zn grades and the abundant sphalerite, pyrite, and galena that were present in outcrop prior to mining. In contrast, despite significant mineralization at the Lik deposit, carbonate rocks in the section buffer the system, resulting in less acidic, mostly near-neutral pH values with low concentrations of most metals except Zn.

Mineralium Deposita

The North Australian Zinc Belt is the largest zinc-lead province in the world, containing three o... more The North Australian Zinc Belt is the largest zinc-lead province in the world, containing three of the ten largest known individual deposits (HYC, Hilton-George Fisher, and Mount Isa). The Northern Cordillera in North America is the second largest zinc-lead province, containing a further two of the world’s top ten deposits (Red Dog and Howards Pass). Despite this world-class endowment, exploration in both mineral provinces during the past 2 decades has not been particularly successful, yielding only two significant discoveries (Teena, Australia, and Boundary, Canada). One of the most important aspects of exploration is to choose mineral provinces and districts within geological belts that have the greatest potential for discovery. Here, we present results from these two zinc belts that highlight previously unused datasets for area selection and targeting. Lead isotope mapping using analyses of mineralized material has identified gradients in μ (238U/204Pb) that coincide closely with...

Open-File Report, 2012

The scope of each of these new mission areas is broader than the science directions outlined in t... more The scope of each of these new mission areas is broader than the science directions outlined in the USGS Science Strategy and together cover the scope of USGS science activities. In 2010, I also commissioned seven Strategic Science Planning Teams (SSPTs) to draft science strategies for each USGS mission area. Although the existing Bureau Science Strategy could be a starting point for this exercise, the SSPTs had to go well beyond the scope of the existing document. What is of value and enduring from the work of the programs that existed under the former science disciplines needed to be reframed and reinterpreted under the new organization of the science mission areas. In addition, new opportunities for research directions have emerged in the five years since the Bureau Science Strategy was drafted, and exciting possibilities for cooperating and collaborating in new ways are enabled by the new mission focus of the organization. Scientists from across the Bureau were selected for these SSPTs for their experience in strategic planning, broad range of experience and expertise, and knowledge of stakeholder needs and relationships. Each SSPT was charged with developing a long-term (10-year) science strategy that encompasses the portfolio of USGS science in the respective mission area. Each science strategy will reinforce others because scientific knowledge inherently has significance to multiple issues. Leadership of the USGS and the Department of the Interior will use the science vision and priorities developed in these strategies for program guidance, implementation planning, accountability reporting, and resource allocation. These strategies will guide science and technology investment and workforce and human capital strategies. They will inform our partners regarding opportunities for communication, collaboration, and coordination. The USGS has taken a significant step toward demonstrating that we are ready to collaborate on the most pressing natural science issues of our day and the future. I believe a leadership aligned to support these issue-based science directions and equipped with the guidance provided in these new science strategies in the capable hands of our scientists will create a new era for USGS of which we can all be proud.

Professional Paper, 2011

In 2005, the U.S. Geological Survey, Bureau of Land Management, and State of Alaska cooperated on... more In 2005, the U.S. Geological Survey, Bureau of Land Management, and State of Alaska cooperated on an investigation of the mineral potential of a southern part of the National Petroleum Reserve in Alaska, Howard Pass quadrangle, to provide background information for future land-use decisions. The investigation incorporated an airborne electromagnetic (EM) survey covering 1,500 mi 2 (~3,900 km 2), including flight lines directly over the Drenchwater Creek sediment-hosted Zn-Pb-Ag occurrence, the largest known base-metal occurrence in the survey area. Samples from the mineralized outcrop and rubblecrop contain metal concentrations that can exceed 11 percent Zn+Pb, with appreciable amounts of Ag. Soil samples with anomalous Pb concentrations are distributed near the sulfide-bearing outcrops and along a >2.5 km zone comprising mudstone, shale, and volcanic rocks of the Kuna Formation. No drilling has taken place at the Drenchwater occurrence, so alternative data sources (for example, geophysics) are especially important in assessing possible indicators of mineralization. Data from the 2005 electromagnetic survey define the geophysical character of the rocks at Drenchwater and, in combination with geological and surface-geochemical data, can aid in assessing the possible shallow (up to about 50 m), subsurface lateral extent of base-metal sulfide accumulations at Drenchwater. A distinct >3-km-long electromagnetic conductive zone (observed in apparent resistivity maps) coincides with, and extends further westward than, mineralized shale outcrops and soils anomalously high in Pb concentrations within the Kuna Formation; this conductive zone may indicate sulfide-rich rock. Models of electrical resistivity with depth, generated from inversion of electromagnetic data, which provide alongflight-line conductivity-depth profiles to between 25 and 50 m below ground surface, show that the shallow subsurface conductive zone occurs in areas of known mineralized outcrops and thins to the east. Broader, more conductive rock along the western ~1 km of the geophysical anomaly does not reach ground surface. These data suggest that the Drenchwater deposit is more extensive than previously thought. The application of inversion modeling also was applied to another smaller geochemical anomaly in the Twistem Creek area. The results are inconclusive, but they suggest that there may be a local conductive zone, possibly due to sulfides.