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#           GIS Prospectivity Analysis for Critical Minerals in Ore-Forming Systems in Alaska      

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      By Alaska Science Center      April 12, 2023    

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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.

**Return to Geology**

View Media Details

The project’s current objective is to quantify and understand the distribution of critical elements in ore-forming systems in Alaska.  It uses a recently developed, data-driven geographic information system (GIS)-based method to evaluate the potential of various mineral deposit types across the state of Alaska. The method systematically analyzes pre-existing, geospatially referenced datasets to generate a map, which provides a visual indication of the estimated potential (high, medium, low) and the certainty of that estimate (high, medium, low) for each watershed in Alaska for a mineral commodity, mineral deposit type, or group of mineral deposit types. Probabilities are calculated with set criteria based on lithology, geochemistry, and geophysical data. The datasets used include the USGS Alaska Geochemical Database, the Alaska Division of Geological and Geophysical Surveys web-based geochemical database, data from the USGS geologic map of Alaska, the USGS Alaska Resource Data File, USGS airborne magnetic surveys, and radiometric surveys from the National Uranium Resource Evaluation.

### GIS-based method

The GIS-based method applies a scoring system to geospatially referenced geologic data in subwatersheds, which are hydrologic units defined by the National Hydrography Dataset and Watershed Boundary Dataset. The scoring system uses multiple parameters based on key characteristics specific to each deposit type. The key characteristics are chosen based on known occurrences of the mineral in deposits around the world, known occurrences in Alaska, and previous research relating to the geologic processes responsible for the formation of these deposit types. Each deposit type has uniquely defined parameters and different point values assigned to the parameters. The parameters are then scored and weighted for each of the different mineral deposit types to generate a score for potential for a concentration of the mineral or deposit type in each watershed. These scores are classified using natural statistical breaks and assigned colors for each watershed for portrayal on maps as shown in the figure: high (red), medium (yellow), low (green), or unknown (gray, owing to lack of data) potential.  The confidence or certainty of the score is then calculated taking into consideration factors such as quantity of data and completeness of the datasets. Levels of confidence are shown as dark (high), medium (medium), or light (low) shades of red, yellow, or green, respectively, for each watershed on the maps.

As an example, the scoring system for placer gold deposits uses five parameters: pan concentrate mineralogy, sediment geochemistry, rock type, geographical location, and whether the Alaska Resource Data File has any reports for the specific area mentioning placer gold as a keyword. Each parameter has a set number of possible points which allows for the parameters to weigh in differently to the total score. For example, pan concentrate data were assigned point values of up to 10, while the presence of plutonic rocks in the watershed could be assigned a maximum of 3 points. In other words, the presence of gold in pan concentrate data indicates a high probability of finding gold in the area; however the presence of plutonic rocks in an area may often, but not always, correlate with placer gold deposits, and thus carries less weight in the overall score. After each parameter is assigned a score and a total score is calculated for each watershed, the certainty of the overall score is determined based on the number of datasets that contributed to the score for each of the parameters in that watershed.

The method is highly adaptable for the needs of diverse users, including scientific researchers, industry, land mangers such as the Bureau of Land Management and the State of Alaska, and Alaska Native corporations. Examples of how this GIS analysis can be applied include:
                                - Identification of areas with high mineral potential supported by abundant data
                                - Identification of understudied and undersampled prospective areas
                                - Topical investigations to improve current deposit models
                                - Development and modification of resource evaluation techniques
                                - Identification and recognition of new pathfinders and different types of data combinations linked to processes of ore genesis
                                - Constraint or expansion of the footprint of known mineral belts
                                - Discovery and definition of new mineral trends or belts

###  

**This project is a continuation of the Alaska Critical Minerals Cooperative Project.**

### Study Area

### Contacts

#### Susan Karl

##### Research Geologist

Alaska Science Center

skarl@usgs.gov

907-786-7428

#### George Case

##### Research Economic Geologist

Alaska Science Center

gcase@usgs.gov

907-786-7472

### Explore Search

                      - Mineral Resources
                      - Alaska Geology and Mineral Resources
                      - Critical Minerals
                      - Databases
                      - Deposit Models
                      - Economic Geology
                      - Geochemical Data
                      - Geospatial (GIS) Data
                      - Mineral Commodities
                      - Rare Earth Elements (REE)
                      - Regional Assessment
                      - Geology
                      - Critical Mineral Resources
                      - Regional Studies and Mineral Resources
                      - Alaska Resource Data File
                      - platinum group elements (PGE)
                      - Geology
                      - Information Systems
                      - Methods and Analyses
                      - Minerals
                      - Science Technology
                      - Mineral Resources Program (MRP)

View All **

Below are other science projects associated with this project.

link

May 24, 2024

####                 Alaska Resource Data File              

Mineral Resources Program, Alaska Science Center

link

May 24, 2024

####   Alaska Resource Data File

Learn More

link

September 30, 2015

####                 Alaska Critical Minerals Cooperative              

Mineral Resources Program, Geology, Minerals, Energy, and Geophysics Science Center

link

September 30, 2015

####   Alaska Critical Minerals Cooperative

Learn More

Below are data releases and webtools associated with this project.

March 21, 2023

####                 Data for Uranium-Lead Geochronology, Carbon and Sulfur Stable Isotopes, and Raman Spectroscopy from Graphite Creek, Alaska              

Alaska Science Center

September 27, 2021

####                 Data from the Chemical Analysis of Archived Stream-Sediment Samples, Alaska              

Alaska Science Center

June 24, 2021

####                 Data and results for GIS-based identification of areas that have resource potential for lode gold deposits in Alaska              

Alaska Science Center

Below are publications associated with this project.

February 27, 2023

####                 Insights into the metamorphic history and origin of flake graphite mineralization at the Graphite Creek graphite deposit, Seward Peninsula, Alaska, USA              

Mineral Resources Program, Alaska Science Center, Geology, Geophysics, and Geochemistry Science Center

September 3, 2019

####                 Alaska Geochemical Database Version 3.0 (AGDB3)—Including “Best Value” Data Compilations for Rock, Sediment, Soil, Mineral, and Concentrate Sample Media              

Mineral Resources Program, Alaska Science Center, Geology, Geophysics, and Geochemistry Science Center

March 3, 2017

####                 Geospatial analysis identifies critical mineral-resource potential in Alaska              

Energy and Minerals Mission Area, Groundwater and Streamflow Information Program, Mineral Resources Program, Alaska Science Center

November 16, 2016

####                 GIS-based identification of areas that have resource potential for critical minerals in six selected groups of deposit types in Alaska              

Alaska Science Center

January 1, 2015

####                 GIS-Based Identification of Areas with Mineral Resource Potential for Six Selected Deposit Groups, Bureau of Land Management Central Yukon Planning Area, Alaska              

Groundwater and Streamflow Information Program, Mineral Resources Program, Alaska Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Geology, Geophysics, and Geochemistry Science Center

USGS Updates Mineral Database with Graphite Deposits in the United States

February 28, 2022

####   USGS Updates Mineral Database with Graphite Deposits in the United States

The U.S. Geological Survey (USGS) has updated the U.S. Mineral Deposit Database (USMIN) to include 10 sites with historical graphite production or...

Read Article

Below are partners associated with this project.

#### U.S. Bureau of Land Management

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.

**Return to Geology**

View Media Details

The project’s current objective is to quantify and understand the distribution of critical elements in ore-forming systems in Alaska.  It uses a recently developed, data-driven geographic information system (GIS)-based method to evaluate the potential of various mineral deposit types across the state of Alaska. The method systematically analyzes pre-existing, geospatially referenced datasets to generate a map, which provides a visual indication of the estimated potential (high, medium, low) and the certainty of that estimate (high, medium, low) for each watershed in Alaska for a mineral commodity, mineral deposit type, or group of mineral deposit types. Probabilities are calculated with set criteria based on lithology, geochemistry, and geophysical data. The datasets used include the USGS Alaska Geochemical Database, the Alaska Division of Geological and Geophysical Surveys web-based geochemical database, data from the USGS geologic map of Alaska, the USGS Alaska Resource Data File, USGS airborne magnetic surveys, and radiometric surveys from the National Uranium Resource Evaluation.

### GIS-based method

The GIS-based method applies a scoring system to geospatially referenced geologic data in subwatersheds, which are hydrologic units defined by the National Hydrography Dataset and Watershed Boundary Dataset. The scoring system uses multiple parameters based on key characteristics specific to each deposit type. The key characteristics are chosen based on known occurrences of the mineral in deposits around the world, known occurrences in Alaska, and previous research relating to the geologic processes responsible for the formation of these deposit types. Each deposit type has uniquely defined parameters and different point values assigned to the parameters. The parameters are then scored and weighted for each of the different mineral deposit types to generate a score for potential for a concentration of the mineral or deposit type in each watershed. These scores are classified using natural statistical breaks and assigned colors for each watershed for portrayal on maps as shown in the figure: high (red), medium (yellow), low (green), or unknown (gray, owing to lack of data) potential.  The confidence or certainty of the score is then calculated taking into consideration factors such as quantity of data and completeness of the datasets. Levels of confidence are shown as dark (high), medium (medium), or light (low) shades of red, yellow, or green, respectively, for each watershed on the maps.

As an example, the scoring system for placer gold deposits uses five parameters: pan concentrate mineralogy, sediment geochemistry, rock type, geographical location, and whether the Alaska Resource Data File has any reports for the specific area mentioning placer gold as a keyword. Each parameter has a set number of possible points which allows for the parameters to weigh in differently to the total score. For example, pan concentrate data were assigned point values of up to 10, while the presence of plutonic rocks in the watershed could be assigned a maximum of 3 points. In other words, the presence of gold in pan concentrate data indicates a high probability of finding gold in the area; however the presence of plutonic rocks in an area may often, but not always, correlate with placer gold deposits, and thus carries less weight in the overall score. After each parameter is assigned a score and a total score is calculated for each watershed, the certainty of the overall score is determined based on the number of datasets that contributed to the score for each of the parameters in that watershed.

The method is highly adaptable for the needs of diverse users, including scientific researchers, industry, land mangers such as the Bureau of Land Management and the State of Alaska, and Alaska Native corporations. Examples of how this GIS analysis can be applied include:
                                - Identification of areas with high mineral potential supported by abundant data
                                - Identification of understudied and undersampled prospective areas
                                - Topical investigations to improve current deposit models
                                - Development and modification of resource evaluation techniques
                                - Identification and recognition of new pathfinders and different types of data combinations linked to processes of ore genesis
                                - Constraint or expansion of the footprint of known mineral belts
                                - Discovery and definition of new mineral trends or belts

###  

**This project is a continuation of the Alaska Critical Minerals Cooperative Project.**

### Study Area

### Contacts

#### Susan Karl

##### Research Geologist

Alaska Science Center

skarl@usgs.gov

907-786-7428

#### George Case

##### Research Economic Geologist

Alaska Science Center

gcase@usgs.gov

907-786-7472

### Explore Search

                      - Mineral Resources
                      - Alaska Geology and Mineral Resources
                      - Critical Minerals
                      - Databases
                      - Deposit Models
                      - Economic Geology
                      - Geochemical Data
                      - Geospatial (GIS) Data
                      - Mineral Commodities
                      - Rare Earth Elements (REE)
                      - Regional Assessment
                      - Geology
                      - Critical Mineral Resources
                      - Regional Studies and Mineral Resources
                      - Alaska Resource Data File
                      - platinum group elements (PGE)
                      - Geology
                      - Information Systems
                      - Methods and Analyses
                      - Minerals
                      - Science Technology
                      - Mineral Resources Program (MRP)

View All **

Below are other science projects associated with this project.

link

May 24, 2024

####                 Alaska Resource Data File              

Mineral Resources Program, Alaska Science Center

link

May 24, 2024

####   Alaska Resource Data File

Learn More

link

September 30, 2015

####                 Alaska Critical Minerals Cooperative              

Mineral Resources Program, Geology, Minerals, Energy, and Geophysics Science Center

link

September 30, 2015

####   Alaska Critical Minerals Cooperative

Learn More

Below are data releases and webtools associated with this project.

March 21, 2023

####                 Data for Uranium-Lead Geochronology, Carbon and Sulfur Stable Isotopes, and Raman Spectroscopy from Graphite Creek, Alaska              

Alaska Science Center

September 27, 2021

####                 Data from the Chemical Analysis of Archived Stream-Sediment Samples, Alaska              

Alaska Science Center

June 24, 2021

####                 Data and results for GIS-based identification of areas that have resource potential for lode gold deposits in Alaska              

Alaska Science Center

Below are publications associated with this project.

February 27, 2023

####                 Insights into the metamorphic history and origin of flake graphite mineralization at the Graphite Creek graphite deposit, Seward Peninsula, Alaska, USA              

Mineral Resources Program, Alaska Science Center, Geology, Geophysics, and Geochemistry Science Center

September 3, 2019

####                 Alaska Geochemical Database Version 3.0 (AGDB3)—Including “Best Value” Data Compilations for Rock, Sediment, Soil, Mineral, and Concentrate Sample Media              

Mineral Resources Program, Alaska Science Center, Geology, Geophysics, and Geochemistry Science Center

March 3, 2017

####                 Geospatial analysis identifies critical mineral-resource potential in Alaska              

Energy and Minerals Mission Area, Groundwater and Streamflow Information Program, Mineral Resources Program, Alaska Science Center

November 16, 2016

####                 GIS-based identification of areas that have resource potential for critical minerals in six selected groups of deposit types in Alaska              

Alaska Science Center

January 1, 2015

####                 GIS-Based Identification of Areas with Mineral Resource Potential for Six Selected Deposit Groups, Bureau of Land Management Central Yukon Planning Area, Alaska              

Groundwater and Streamflow Information Program, Mineral Resources Program, Alaska Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Geology, Geophysics, and Geochemistry Science Center

USGS Updates Mineral Database with Graphite Deposits in the United States

February 28, 2022

####   USGS Updates Mineral Database with Graphite Deposits in the United States

The U.S. Geological Survey (USGS) has updated the U.S. Mineral Deposit Database (USMIN) to include 10 sites with historical graphite production or...

Read Article

Below are partners associated with this project.

#### U.S. Bureau of Land Management