Map showing locations of placer mines in the Alaska Resource Data File (ARDF, red crosses), primary mineral districts that contain targeted critical minerals (black boxes) and locations that were sampled by the USGS in 2022 and 2023 (yellow stars).
Susan Karl
Sedimentology, stratigraphy, tectonics, geochemistry, and economic geology of southeast Alaska
Professional Experience
1977 - Present Research Geologist, USGS Alaska Science Center, Anchorage, AK
1976 Earth Science Associates, Palo Alto, CA
1975 WGM Inc., Brooks Range, AK
1974 Rio Tinto Ltd., Wrangell Mts, AK
Education and Certifications
Ph.D. 1982 Stanford University
Classes 1975-1976 University of Alaska Fairbanks
B.A. 1973 Middlebury College
Affiliations and Memberships*
Fellow: Geological Soc. America
Member: American Geophysical Union, American Assoc. Petrol. Geol., Geological Assoc. Canada, Society of Economic Geologists
Short course committee chair: Alaska Miners Association
Board member, committee chair, past president, officer: Alaska Geological Society
Honors and Awards
Amer. Assoc. Petroleum Geologists: Lifetime service award, May 2016, for contributions to the Alaska geological community
Outstanding Accomplishment award 11-18-2011 for contributions to understanding REE in southeast Alaska
Outstanding Accomplishment award 11-22-2010 for advances in southeast Alaska geology
Outstanding Accomplishment award 9-22-2009 for work with Yukon Territory, British Columbia, and Alaskan geologists to coordinate cross-border geology
USGS: STAR award 1999 for Stikine area geophysical survey follow-up project (Duncan Canal/Zarembo Island area VMS deposits)
Alaska Geol. Soc: Service award, 1995
UNESCO: Grant for IGCP Siliceous Deposits Conference (Yugoslavia), 1986
USGS: Graduate internship scholarship 1981, 1982
UNESCO: Grant for IGCP Siliceous Deposits Conference (Tokyo), 1981
Geol. Soc. America: Grant for thesis research 1981
Sigma Xi: Grant for thesis research, 1980, 1981
USGS Achievement Award 1979
Shell: Grant for Melange Penrose Conference, 1978
Geol. Soc. Amer: Harold Stearns Award and grant for thesis research, 1978
UAF: grant for field camp 1976
Science and Products
Alaska Critical Mineral Resource Assessments
GIS Prospectivity Analysis for Critical Minerals in Ore-Forming Systems in Alaska
Petrology, Tectonic Setting, and Potential for Concentration of Rare Earth Elements (REE) and High Field Strength Elements (HFSE) in the High-K Darby and Kachauik Plutons, Seward Peninsula, Alaska
Data for Uranium-Lead Geochronology, Carbon and Sulfur Stable Isotopes, and Raman Spectroscopy from Graphite Creek, Alaska
Whole Rock Major and Trace Element Chemistry for Igneous Rocks from Tyonek, Lime Hills, Talkeetna, McGrath, and Lake Clark Quadrangles, Western Alaska Range, Alaska
Whole Rock Major and Trace Element Chemistry for Igneous and Sedimentary Rocks from the Western Alaska Range, Alaska
Data from the Chemical Analysis of Archived Stream-Sediment Samples, Alaska
Data and results for GIS-based identification of areas that have resource potential for lode gold deposits in Alaska
Geochemical and 40Ar/39Ar Analytical Data of Rocks from Glacier Bay National Park and Preserve
U-Pb Isotopic Data and Ages of Zircon and Titanite from Rocks from the Western Alaska Range, Northern Aleutian Range, Taylor Mountains, and Tikchik Mountains Regions, Alaska
U-Pb Isotopic Data and Ages of Titanite and Detrital Zircon from Selected Rocks from the Western Alaska Range, Alaska
Alaska Geochemical Database Version 3.0 (AGDB3) including best value data compilations for rock, sediment, soil, mineral, and concentrate sample media
Geologic Map of Baranof Island, southeastern Alaska
Geologic map of Alaska
Geologic map of western Chichagof and Yakobi islands, southeastern Alaska
Map showing locations of placer mines in the Alaska Resource Data File (ARDF, red crosses), primary mineral districts that contain targeted critical minerals (black boxes) and locations that were sampled by the USGS in 2022 and 2023 (yellow stars).
Scientist sieving a sample of gold placer tailings to analyze for critical mineral contents in Uhler Creek, a tributary to the South Fork of the Forty Mile River in east central Alaska.
Scientist sieving a sample of gold placer tailings to analyze for critical mineral contents in Uhler Creek, a tributary to the South Fork of the Forty Mile River in east central Alaska.
Scientist sieving a sample of tin placer tailings in Cassiterite Creek on the western Seward Peninsula.
Scientist sieving a sample of tin placer tailings in Cassiterite Creek on the western Seward Peninsula.
Historic dredge and large volume of gold placer tailings that contain platinum group and chromium critical minerals on the Salmon River near Goodnews Bay, Alaska. Dragline-sluice tailings are in the foreground, stacked dredge tailings are in the background near the dredge.
Historic dredge and large volume of gold placer tailings that contain platinum group and chromium critical minerals on the Salmon River near Goodnews Bay, Alaska. Dragline-sluice tailings are in the foreground, stacked dredge tailings are in the background near the dredge.
Scientists collecting a 1/5 yard composite sample in blue 5-gallon buckets from gold placer tailings to analyze for critical mineral contents in Clear Creek, in the Zane Hills north central Alaska.
Scientists collecting a 1/5 yard composite sample in blue 5-gallon buckets from gold placer tailings to analyze for critical mineral contents in Clear Creek, in the Zane Hills north central Alaska.
Scientist checking a gold pan for gold and critical minerals in placer tailings on lower Chicken Creek near Flat, Alaska, in the Kuskokwim Mountains. A sample was collected from legacy gold placer tailings at this site and 7 others in the Flat mining district to determine the critical mineral contents of tailings from which only gold has been removed.
Scientist checking a gold pan for gold and critical minerals in placer tailings on lower Chicken Creek near Flat, Alaska, in the Kuskokwim Mountains. A sample was collected from legacy gold placer tailings at this site and 7 others in the Flat mining district to determine the critical mineral contents of tailings from which only gold has been removed.
USGS geologist George Case is recording data on graphite mineralization in core sample from the Graphite Creek deposit in Nome, Alaska. The purpose of this research is to determine the genesis and key attributes of the world class large flake Graphite Creek deposit on the western Seward Peninsula, Alaska.
USGS geologist George Case is recording data on graphite mineralization in core sample from the Graphite Creek deposit in Nome, Alaska. The purpose of this research is to determine the genesis and key attributes of the world class large flake Graphite Creek deposit on the western Seward Peninsula, Alaska.
A geologist, George Case, stands in front of an adit, an entrance to an underground mine, in the Graphite Creek Deposit on the Seward Peninsula, Alaska.
A geologist, George Case, stands in front of an adit, an entrance to an underground mine, in the Graphite Creek Deposit on the Seward Peninsula, Alaska.
View of fog and clouds in the Aaron Creek valley with tail of R66 helicopter in right foreground.
View of fog and clouds in the Aaron Creek valley with tail of R66 helicopter in right foreground.
Geologist George Case approaches an old exploration trench exposing stratiform Ag-Sn-Pb-Zn mineralization in the Groundhog Basin deposit area.
Geologist George Case approaches an old exploration trench exposing stratiform Ag-Sn-Pb-Zn mineralization in the Groundhog Basin deposit area.
Rock hammer shows meter-scale width of a felsic sill associated with zinnwaldite-bearing Sn-granite at the Groundhog Basin Ag-Sn-Pb-Zn deposit. The layered host rocks to the sill are garnet-quartz-biotite gneiss.
Rock hammer shows meter-scale width of a felsic sill associated with zinnwaldite-bearing Sn-granite at the Groundhog Basin Ag-Sn-Pb-Zn deposit. The layered host rocks to the sill are garnet-quartz-biotite gneiss.
USGS geologist George Case approaches an R66 helicopter with samples collected from mineralized rocks near the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case approaches an R66 helicopter with samples collected from mineralized rocks near the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case breaks mineralized rocks for examination and sample collection at the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case breaks mineralized rocks for examination and sample collection at the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS Geologist George Case examines granitic rocks in preparation for collecting samples for geochemistry and geochronology near the Boulder Creek prospect at the north end of the Darby pluton on the eastern Seward Peninsula.
USGS Geologist George Case examines granitic rocks in preparation for collecting samples for geochemistry and geochronology near the Boulder Creek prospect at the north end of the Darby pluton on the eastern Seward Peninsula.
Stretched phenocrysts of potassium feldspar in syenite of the Kachauik pluton on the Bering Sea coast of the southeastern Seward Peninsula.
Stretched phenocrysts of potassium feldspar in syenite of the Kachauik pluton on the Bering Sea coast of the southeastern Seward Peninsula.
Scintillometer and torrs of the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements. This area is part of the Bureau of Land Management's Central Yukon Planning Area, which USGS did a mineral assessment of in 2015.
Scintillometer and torrs of the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements. This area is part of the Bureau of Land Management's Central Yukon Planning Area, which USGS did a mineral assessment of in 2015.
Geologist and cataclastic shear zones in the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements.
Geologist and cataclastic shear zones in the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements.
USGS researchers collecting a soil sample for rare earth elements at the Roy Creek prospect, Alaska. Jamey Jones is holding the bag while Erin Todd shovels soil into the bag.
USGS researchers collecting a soil sample for rare earth elements at the Roy Creek prospect, Alaska. Jamey Jones is holding the bag while Erin Todd shovels soil into the bag.
A field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.
A field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.
Insights into the metamorphic history and origin of flake graphite mineralization at the Graphite Creek graphite deposit, Seward Peninsula, Alaska, USA
Geospatial analysis delineates lode gold prospectivity in Alaska
GIS-based identification of areas that have resource potential for lode gold in Alaska
Chemical analysis of archived stream-sediment samples, Alaska
Cretaceous to Oligocene magmatic and tectonic evolution of the western Alaska Range: Insights from U-Pb and 40Ar/39Ar geochronology
Evaluation of the analytical methods used to determine the elemental concentrations found in the stream geochemical dataset compiled for Alaska
Detrital zircon geochronology along a structural transect across the Kahiltna assemblage in the western Alaska Range: Implications for emplacement of the Alexander-Wrangellia-Peninsular terrane against North America
Alaska Geochemical Database Version 3.0 (AGDB3)—Including “Best Value” Data Compilations for Rock, Sediment, Soil, Mineral, and Concentrate Sample Media
Geospatial analysis identifies critical mineral-resource potential in Alaska
Regional patterns of Mesozoic-Cenozoic magmatism in western Alaska revealed by new U-Pb and 40Ar/39Ar ages
In support of regional geologic framework studies, we obtained 50 new argon-40/argon-39 (40Ar/39Ar) ages and 33 new uranium-lead (U-Pb) ages from igneous rocks of southwestern Alaska. Most of the samples are from the Sleetmute and Taylor Mountains quadrangles; smaller collections or individual samples are from the Bethel, Candle, Dillingham, Goodnews Bay, Holy Cross, Iditarod, Kantishna River, Lak
The Peters Hills basin, a Neogene wedge-top basin on the Broad Pass thrust fault, south-central Alaska
GIS-based identification of areas that have resource potential for critical minerals in six selected groups of deposit types in Alaska
Science and Products
- Science
Alaska Critical Mineral Resource Assessments
Alaska has potential for a wide range of critical minerals including, but not limited to, graphite, lithium, tin, tungsten, rare earth elements, and platinum-group elements.GIS Prospectivity Analysis for Critical Minerals in Ore-Forming Systems in Alaska
Alaska is dominated by a history of tectonic events that foster mobilization and concentration of a wide variety of mineral commodities that are critical to the US economy and are vital to national defense, renewable-energy, and emerging electronics technologies.Petrology, Tectonic Setting, and Potential for Concentration of Rare Earth Elements (REE) and High Field Strength Elements (HFSE) in the High-K Darby and Kachauik Plutons, Seward Peninsula, Alaska
One of the geologic environments that host rare earth and other critical and strategic element deposits are alkaline intrusive rocks. - Data
Data for Uranium-Lead Geochronology, Carbon and Sulfur Stable Isotopes, and Raman Spectroscopy from Graphite Creek, Alaska
This data release supports the paper titled, "Insights into the metamorphic history and origin of flake graphite mineralization at the Graphite Creek graphite deposit, Seward Peninsula, Alaska, USA", published in the journal Mineralium Deposita. The data release includes zircon and titanite U-Pb-Thisotope and age data, monazite U-Pb-Th isotope, trace element and age data, carbon and sulfur stableiWhole Rock Major and Trace Element Chemistry for Igneous Rocks from Tyonek, Lime Hills, Talkeetna, McGrath, and Lake Clark Quadrangles, Western Alaska Range, Alaska
This data release contains whole rock major and trace element data for 69 igneous rock samples collected from the Western Alaska Range between 2011 and 2012. The Series field relates to chronological units discussed in Jones et al. (2021, Geosphere) and Todd et al. (2022 IN PREP). Descriptions are from original collector notebooks and are provided here for informational purposes only.Whole Rock Major and Trace Element Chemistry for Igneous and Sedimentary Rocks from the Western Alaska Range, Alaska
This data release contains whole rock major and trace element data for 399 igneous and sedimentary rock samples collected from the Western Alaska Range between 1968 and 2014 and funded by the Mineral Resources Program of the U.S. Geological Survey. All materials were analyzed by ALS Global, between 2014 and 2018, by a range of different techniques, so multiple unique entries for a given element reData from the Chemical Analysis of Archived Stream-Sediment Samples, Alaska
This data release contains the elemental concentration data for more than 1700 archived stream-sediment samples collected in Alaska. Samples were retrieved from the USGS Mineral Program's sample archive in Denver, CO, and the Alaska Division of Geological and Geophysical Surveys Geologic Materials Center in Anchorage, AK. All samples were analyzed using a multi-element analytical method involvingData and results for GIS-based identification of areas that have resource potential for lode gold deposits in Alaska
This data release contains the analytical results and evaluated source data files of geospatial analyses for identifying areas in Alaska that may be prospective for different types of lode gold deposits, including orogenic, reduced-intrusion-related, epithermal, and gold-bearing porphyry. The spatial analysis is based on queries of statewide source datasets of aeromagnetic surveys, Alaska GeochemiGeochemical and 40Ar/39Ar Analytical Data of Rocks from Glacier Bay National Park and Preserve
This data set contains major and trace element geochemical data and 40Ar/39Ar isotopic data and ages for rock samples collected during 2016 fieldwork in Glacier Bay National Park and Preserve. The plutonic rock samples were collected for radiometric age determinations to test for the presence of the Late Jurassic to Early Cretaceous (130-160 Ma) Saint Elias suite. The age analyses indicate that alU-Pb Isotopic Data and Ages of Zircon and Titanite from Rocks from the Western Alaska Range, Northern Aleutian Range, Taylor Mountains, and Tikchik Mountains Regions, Alaska
This data set contains U-Pb isotopic data and ages of zircon and titanite from igneous and metamorphic rocks collected from the western Alaska and northern Aleutian Range of south-central Alaska. The data sets also contain U-Pb isotopic data and ages of detrital zircon from sedimentary and metasedimentary rocks collected in the same region but also from the Taylor and Wood River Mountains of southU-Pb Isotopic Data and Ages of Titanite and Detrital Zircon from Selected Rocks from the Western Alaska Range, Alaska
This data set contains U-Pb isotopic data and associated ages of titanite from one sample and detrital zircon grains from 33 sedimentary and metasedimentary rocks collected from the western Alaska Range in south-central Alaska. The samples were collected as part of geological mapping and research conducted between 2010 and 2014 and funded by the Mineral Resources Program of the U.S. Geological SurAlaska Geochemical Database Version 3.0 (AGDB3) including best value data compilations for rock, sediment, soil, mineral, and concentrate sample media
The Alaska Geochemical Database Version 3.0 (AGDB3) contains new geochemical data compilations in which each geologic material sample has one best value determination for each analyzed species, greatly improving speed and efficiency of use. Like the Alaska Geochemical Database Version 2.0 before it, the AGDB3 was created and designed to compile and integrate geochemical data from Alaska to facilit - Maps
Geologic Map of Baranof Island, southeastern Alaska
This map updates the geology of Baranof Island based on fieldwork, petrographic analyses, paleontologic ages, and isotopic ages. These new data provide constraints on depositional and metamorphic ages of lithostratigraphic rock units and the timing of structures that separate them. Kinematic analyses and thermobarometric calculations provide insights on the regional tectonic processes that affecteGeologic map of Alaska
Summary This map and associated digital databases are the result of compilation and interpretation of published and unpublished 1:250,000-scale and limited 1:500,000- to 1:63,360-scale maps. Covering the entire state of Alaska, it reflects more than a century of work by a host of geologists and almost two decades of compilation work. There are two versions of the map: a detailed digital version, aGeologic map of western Chichagof and Yakobi islands, southeastern Alaska
No abstract available. - Multimedia
Alaska locations of placer tailings sampling sitesAlaska locations of placer tailings sampling sites
Map showing locations of placer mines in the Alaska Resource Data File (ARDF, red crosses), primary mineral districts that contain targeted critical minerals (black boxes) and locations that were sampled by the USGS in 2022 and 2023 (yellow stars).
Map showing locations of placer mines in the Alaska Resource Data File (ARDF, red crosses), primary mineral districts that contain targeted critical minerals (black boxes) and locations that were sampled by the USGS in 2022 and 2023 (yellow stars).
Uhler CreekScientist sieving a sample of gold placer tailings to analyze for critical mineral contents in Uhler Creek, a tributary to the South Fork of the Forty Mile River in east central Alaska.
Scientist sieving a sample of gold placer tailings to analyze for critical mineral contents in Uhler Creek, a tributary to the South Fork of the Forty Mile River in east central Alaska.
Cassiterite CreekScientist sieving a sample of tin placer tailings in Cassiterite Creek on the western Seward Peninsula.
Scientist sieving a sample of tin placer tailings in Cassiterite Creek on the western Seward Peninsula.
DredgeHistoric dredge and large volume of gold placer tailings that contain platinum group and chromium critical minerals on the Salmon River near Goodnews Bay, Alaska. Dragline-sluice tailings are in the foreground, stacked dredge tailings are in the background near the dredge.
Historic dredge and large volume of gold placer tailings that contain platinum group and chromium critical minerals on the Salmon River near Goodnews Bay, Alaska. Dragline-sluice tailings are in the foreground, stacked dredge tailings are in the background near the dredge.
Clear CreekScientists collecting a 1/5 yard composite sample in blue 5-gallon buckets from gold placer tailings to analyze for critical mineral contents in Clear Creek, in the Zane Hills north central Alaska.
Scientists collecting a 1/5 yard composite sample in blue 5-gallon buckets from gold placer tailings to analyze for critical mineral contents in Clear Creek, in the Zane Hills north central Alaska.
Chicken CreekScientist checking a gold pan for gold and critical minerals in placer tailings on lower Chicken Creek near Flat, Alaska, in the Kuskokwim Mountains. A sample was collected from legacy gold placer tailings at this site and 7 others in the Flat mining district to determine the critical mineral contents of tailings from which only gold has been removed.
Scientist checking a gold pan for gold and critical minerals in placer tailings on lower Chicken Creek near Flat, Alaska, in the Kuskokwim Mountains. A sample was collected from legacy gold placer tailings at this site and 7 others in the Flat mining district to determine the critical mineral contents of tailings from which only gold has been removed.
USGS geologist recording data on graphite mineralization in core sampleUSGS geologist recording data on graphite mineralization in core sampleUSGS geologist George Case is recording data on graphite mineralization in core sample from the Graphite Creek deposit in Nome, Alaska. The purpose of this research is to determine the genesis and key attributes of the world class large flake Graphite Creek deposit on the western Seward Peninsula, Alaska.
USGS geologist George Case is recording data on graphite mineralization in core sample from the Graphite Creek deposit in Nome, Alaska. The purpose of this research is to determine the genesis and key attributes of the world class large flake Graphite Creek deposit on the western Seward Peninsula, Alaska.
Evidence of previous explorationA geologist, George Case, stands in front of an adit, an entrance to an underground mine, in the Graphite Creek Deposit on the Seward Peninsula, Alaska.
A geologist, George Case, stands in front of an adit, an entrance to an underground mine, in the Graphite Creek Deposit on the Seward Peninsula, Alaska.
View of fog and clouds in the Aaron Creek valley, AlaskaView of fog and clouds in the Aaron Creek valley, AlaskaView of fog and clouds in the Aaron Creek valley with tail of R66 helicopter in right foreground.
View of fog and clouds in the Aaron Creek valley with tail of R66 helicopter in right foreground.
USGS Geologist approaches an old exploration trenchUSGS Geologist approaches an old exploration trenchGeologist George Case approaches an old exploration trench exposing stratiform Ag-Sn-Pb-Zn mineralization in the Groundhog Basin deposit area.
Geologist George Case approaches an old exploration trench exposing stratiform Ag-Sn-Pb-Zn mineralization in the Groundhog Basin deposit area.
Rock hammer shows meter-scale width of a felsic sillRock hammer shows meter-scale width of a felsic sillRock hammer shows meter-scale width of a felsic sill associated with zinnwaldite-bearing Sn-granite at the Groundhog Basin Ag-Sn-Pb-Zn deposit. The layered host rocks to the sill are garnet-quartz-biotite gneiss.
Rock hammer shows meter-scale width of a felsic sill associated with zinnwaldite-bearing Sn-granite at the Groundhog Basin Ag-Sn-Pb-Zn deposit. The layered host rocks to the sill are garnet-quartz-biotite gneiss.
USGS geologist approaches helicopter with samplesUSGS geologist George Case approaches an R66 helicopter with samples collected from mineralized rocks near the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case approaches an R66 helicopter with samples collected from mineralized rocks near the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist breaks mineralized rocks for examination and sample collectionUSGS geologist breaks mineralized rocks for examination and sample collectionUSGS geologist George Case breaks mineralized rocks for examination and sample collection at the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case breaks mineralized rocks for examination and sample collection at the Groundhog Basin Ag-Sn-Pb-Zn deposit.
Geologist examines rocks at Darby Pluton, AKUSGS Geologist George Case examines granitic rocks in preparation for collecting samples for geochemistry and geochronology near the Boulder Creek prospect at the north end of the Darby pluton on the eastern Seward Peninsula.
USGS Geologist George Case examines granitic rocks in preparation for collecting samples for geochemistry and geochronology near the Boulder Creek prospect at the north end of the Darby pluton on the eastern Seward Peninsula.
Potassium feldspar phenocrysts in syeniteStretched phenocrysts of potassium feldspar in syenite of the Kachauik pluton on the Bering Sea coast of the southeastern Seward Peninsula.
Stretched phenocrysts of potassium feldspar in syenite of the Kachauik pluton on the Bering Sea coast of the southeastern Seward Peninsula.
Torrs of the Ruby BatholithScintillometer and torrs of the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements. This area is part of the Bureau of Land Management's Central Yukon Planning Area, which USGS did a mineral assessment of in 2015.
Scintillometer and torrs of the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements. This area is part of the Bureau of Land Management's Central Yukon Planning Area, which USGS did a mineral assessment of in 2015.
Shearing of the Melozitna GraniteGeologist and cataclastic shear zones in the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements.
Geologist and cataclastic shear zones in the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements.
Taking soil samplesUSGS researchers collecting a soil sample for rare earth elements at the Roy Creek prospect, Alaska. Jamey Jones is holding the bag while Erin Todd shovels soil into the bag.
USGS researchers collecting a soil sample for rare earth elements at the Roy Creek prospect, Alaska. Jamey Jones is holding the bag while Erin Todd shovels soil into the bag.
Panning for Rare EarthsA field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.
A field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.
- Publications
Filter Total Items: 63
Insights into the metamorphic history and origin of flake graphite mineralization at the Graphite Creek graphite deposit, Seward Peninsula, Alaska, USA
Graphite Creek is an unusual flake graphite deposit located on the Seward Peninsula, Alaska, USA. We present field observations, uranium-lead (U–Pb) monazite and titanite geochronology, carbon (C) and sulfur (S) stable isotope geochemistry, and graphite Raman spectroscopy data from this deposit that support a new model of flake graphite ore genesis in high-grade metamorphic environments. The GraphAuthorsGeorge N. D. Case, Susan M. Karl, Sean P. Regan, Craig A. Johnson, Eric T Ellison, Jonathan Caine, Christopher Holm-Denoma, Laura Pianowski, Jeff A. BenowitzGeospatial analysis delineates lode gold prospectivity in Alaska
Comprehensive, data-driven geographic information system analyses utilize publicly available lithologic, geochemical, geophysical, and mineral occurrence datasets to delineate gold resource potential in Alaska. These prospectivity analyses successfully identify areas containing known lode gold occurrences, expand areas of high prospectivity around known occurrences, improve the precision of delineAuthorsSusan M. Karl, Douglas C. Kreiner, George N. D. Case, Keith A. LabayGIS-based identification of areas that have resource potential for lode gold in Alaska
Several comprehensive, data-driven geographic information system (GIS) analyses were conducted to assess prospectivity for lode gold in Alaska. These analyses use available geospatial datasets of lithologic, geochemical, mineral occurrence, and geophysical data to build models for recognizing different types of gold deposits within physiographic units defined by stream drainage basins that are appAuthorsSusan M. Karl, Douglas C. Kreiner, George N. D. Case, Keith A. Labay, Nora B. Shew, Matthew Granitto, Bronwen Wang, Eric D. AndersonChemical analysis of archived stream-sediment samples, Alaska
Geochemical data are presented for more than 1,500 archived stream-sediment samples and accompanying quality control samples. The archived sediments were reanalyzed to improve the stream geochemical dataset for Alaska and to support ongoing U.S. Geological Survey (USGS) studies. Sediment samples were primarily from the USGS Mineral Resources Program’s sample archive in Denver, Colorado, but a fewAuthorsBronwen Wang, George N. D. Case, Mathew Granitto, Keith A. Labay, Nora B. Shew, Andrew D. Ingraham, Jaime S. Azain, Zachary C. Bueghly, Susan M. Karl, Karen D. KelleyCretaceous to Oligocene magmatic and tectonic evolution of the western Alaska Range: Insights from U-Pb and 40Ar/39Ar geochronology
New U-Pb and 40Ar/39Ar ages integrated with geologic mapping and observations across the western Alaska Range constrain the distribution and tectonic setting of Cretaceous to Oligocene magmatism along an evolving accretionary plate margin in south-central Alaska. These rocks were emplaced across basement domains that include Neoproterozoic to Jurassic carbonate and siliciclastic strata of the FareAuthorsJames V. Jones, Erin Todd, Stephen E. Box, Peter J. Haeussler, Christopher Holm-Denoma, Susan M. Karl, Garth E. Graham, Dwight C. Bradley, Andrew R.C. Kylander-Clark, Richard M. Friedman, Paul W. LayerEvaluation of the analytical methods used to determine the elemental concentrations found in the stream geochemical dataset compiled for Alaska
A recent U.S. Geological Survey data compilation of stream-sediment geochemistry for Alaska contains decades of analyses collected under numerous Federal and State programs. The compiled data were determined by various analytical methods. Some samples were reanalyzed by a different analytical method than the original, resulting in some elements having concentrations reported by multiple analyticalAuthorsBronwen Wang, Karl J. Ellefsen, Matthew Granitto, Karen D. Kelley, Susan M. Karl, George N. D. Case, Douglas C. Kreiner, Courtney L. AmundsonDetrital zircon geochronology along a structural transect across the Kahiltna assemblage in the western Alaska Range: Implications for emplacement of the Alexander-Wrangellia-Peninsular terrane against North America
The Kahiltna assemblage in the western Alaska Range consists of deformed Upper Jurassic and Cretaceous clastic strata that lie between the Alexander-Wrangellia-Peninsular (AWP) terrane to the south, and the Farewell and other peri-cratonic terranes to the north. Differences in detrital zircon populations and sandstone petrography allow geographic separation of the strata into two different successAuthorsStephen E. Box, Susan M. Karl, James V. Jones, Dwight C. Bradley, Peter J. Haeussler, Paul B. O'SullivanAlaska Geochemical Database Version 3.0 (AGDB3)—Including “Best Value” Data Compilations for Rock, Sediment, Soil, Mineral, and Concentrate Sample Media
The Alaska Geochemical Database Version 3.0 (AGDB3) contains new geochemical data compilations in which each geologic material sample has one “best value” determination for each analyzed species, greatly improving speed and efficiency of use. Like the Alaska Geochemical Database Version 2.0 before it, the AGDB3 was created and designed to compile and integrate geochemical data from Alaska to facilAuthorsMatthew Granitto, Bronwen Wang, Nora B. Shew, Susan M. Karl, Keith A. Labay, Melanie B. Werdon, Susan S. Seitz, John E. HoppeGeospatial analysis identifies critical mineral-resource potential in Alaska
Alaska consists of more than 663,000 square miles (1,717,000 square kilometers) of land—more than a sixth of the total area of the United States—and large tracts of it have not been systematically studied or sampled for mineral-resource potential. Many regions of the State are known to have significant mineral-resource potential, and there are currently six operating mines in the State along withAuthorsSusan M. Karl, Keith A. LabayRegional patterns of Mesozoic-Cenozoic magmatism in western Alaska revealed by new U-Pb and 40Ar/39Ar ages
In support of regional geologic framework studies, we obtained 50 new argon-40/argon-39 (40Ar/39Ar) ages and 33 new uranium-lead (U-Pb) ages from igneous rocks of southwestern Alaska. Most of the samples are from the Sleetmute and Taylor Mountains quadrangles; smaller collections or individual samples are from the Bethel, Candle, Dillingham, Goodnews Bay, Holy Cross, Iditarod, Kantishna River, Lak
AuthorsDwight C. Bradley, Marti L. Miller, Richard M. Friedman, Paul W. Layer, Heather A. Bleick, James V. Jones, Steven E. Box, Susan M. Karl, Nora B. Shew, Timothy S. White, Alison B. Till, Julie A. Dumoulin, Thomas K. Bundtzen, Paul B. O'Sullivan, Thomas D. UllrichThe Peters Hills basin, a Neogene wedge-top basin on the Broad Pass thrust fault, south-central Alaska
The Neogene Peters Hills basin is a small terrestrial basin that formed along the south flank of the Alaska Range during a time in which there was regional shortening. The formation of the Peters Hills basin is consistent with it being a wedge-top basin that formed on top of the active southeast-vergent Broad Pass thrust fault. Movement along this thrust raised a ridge of Jurassic and Cretaceous mAuthorsPeter J. Haeussler, Richard W. Saltus, Richard G. Stanley, Natalia Ruppert, Kristen Lewis, Susan M. Karl, Adrian M. BenderGIS-based identification of areas that have resource potential for critical minerals in six selected groups of deposit types in Alaska
Alaska has considerable potential for undiscovered mineral resources. This report evaluates potential for undiscovered critical minerals in Alaska. Critical minerals are those for which the United States imports more than half of its total supply and which are largely derived from nations that cannot be considered reliable trading partners. In this report, estimated resource potential and certaint - News
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government