This project supports the USGS argon geochronology laboratory in Denver. The USGS 40Ar/39Ar geochronology laboratory is a state-of-the-art research facility for determining absolute ages of minerals and rocks. The 40Ar/39Ar laboratory contributes critical geochronology to individual USGS research projects and to partners in academia and other Federal agencies. This laboratory develops methodology for small and difficult sample analysis often at the limits of existing mass spectrometer technology.
Science Issue and Relevance
The 40Ar/39Ar Method: 40Ar/39Ar geochronology is an experimentally robust and versatile method for constraining the age and thermal history of rocks. Such information is extremely valuable for understanding a variety of geological processes including the formation of ore deposits, mountain building and history of volcanic events, paleo-seismic events, and paleo-climate. The 40Ar/39Ar isotopic dating method has evolved into the most commonly applied geochronological method, and can be applied to many geological problems that require precise and accurate time and temperature control.
Methodology to Address Issue
This project provides partial support for the USGS argon geochronology laboratory in Denver. The USGS 40Ar/39Ar geochronology laboratory is a state-of-the-art research facility for determining absolute ages of minerals and rocks. The 40Ar/39Ar laboratory contributes critical geochronology to individual USGS research projects and to partners in academia and other Federal agencies. This facility houses necessary equipment for sample preparation and analysis, including high-sensitivity noble gas mass spectrometers and ultraviolet (UV) and infrared (IR) lasers. The versatility of the 40Ar/39Ar method permits determining the timing of processes and events such as igneous intrusions and extrusions, ore mineralization and hydrothermal fluid circulation, metamorphic cooling and exhumation, mineral formation and recrystallization, and shallow crustal faulting. Scientists are dependent on the geochronologist for data and interpretations to determine these parameters. This laboratory develops methodology for small and difficult sample analysis often at the limits of existing mass spectrometer technology.
Below are other science projects associated with this project.
Porphyry Copper Systems of the Boulder batholith, Montana
USGS Geochron: A database of USGS geochronological and thermochronological data
Evaluation of Critical Elements in Carbonatites
Geologic Framework of the Intermountain West
Serving the U.S. Geological Survey’s geochronological data
Below are data releases associated with this project. Visit USGS Geochron - a database of geochronologic and thermochronologic dates and data.
Argon data for samples from Kenya and Ethiopia Argon data for samples from Kenya and Ethiopia
Argon Data for samples from the Elkhead and Rabbit Ears Mountains, northern Colorado, USA Argon Data for samples from the Elkhead and Rabbit Ears Mountains, northern Colorado, USA
U-Pb detrital zircon data and Ar feldspar data from middle Cenozoic sandstones and volcanic tuffs from southern Nevada, USA U-Pb detrital zircon data and Ar feldspar data from middle Cenozoic sandstones and volcanic tuffs from southern Nevada, USA
Argon data for enriched MORB from the 8°20' N seamount chain Argon data for enriched MORB from the 8°20' N seamount chain
Quetrupillán Volcanic Complex, southern Chile: Argon age data and Pb, Sr, and Nd isotopic data Quetrupillán Volcanic Complex, southern Chile: Argon age data and Pb, Sr, and Nd isotopic data
Argon and SHRIMP-RG Data for Magmatic Steam Alunite, Sericite, and Zircon from Alunite Ridge and Deer Trail Mountain, Marysvale, Utah Argon and SHRIMP-RG Data for Magmatic Steam Alunite, Sericite, and Zircon from Alunite Ridge and Deer Trail Mountain, Marysvale, Utah
USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data (ver. 4.0, May 2025) USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data (ver. 4.0, May 2025)
Argon data for HD-B1 intercalibration Argon data for HD-B1 intercalibration
Argon data for Santa Cruz Basin (ver. 1.1, November 2022) Argon data for Santa Cruz Basin (ver. 1.1, November 2022)
Argon data for Hugub Area, Kesem-Kebena-Dulecha, Ethiopia Argon data for Hugub Area, Kesem-Kebena-Dulecha, Ethiopia
Argon data for Klamath Mountains Argon data for Klamath Mountains
Argon data for Nepal Argon data for Nepal
Using the potassium-argon laser experiment (KArLE) to date ancient, low-K chondritic meteorites Using the potassium-argon laser experiment (KArLE) to date ancient, low-K chondritic meteorites
Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado
Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado
Geologic map of the upper Arkansas River valley region, north-central Colorado Geologic map of the upper Arkansas River valley region, north-central Colorado
Geologic map of the Rio Rico and Nogales 7.5’ quadrangles, Santa Cruz County, Arizona Geologic map of the Rio Rico and Nogales 7.5’ quadrangles, Santa Cruz County, Arizona
Geologic map of the Sunshine 7.5' quadrangle, Taos County, New Mexico Geologic map of the Sunshine 7.5' quadrangle, Taos County, New Mexico
Geologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado Geologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado
Geologic map of the Harvard Lakes 7.5' quadrangle, Park and Chaffee Counties, Colorado Geologic map of the Harvard Lakes 7.5' quadrangle, Park and Chaffee Counties, Colorado
Below are publications associated with this project.
Bayesian calibration of the 40K decay scheme with implications for 40K-based geochronology Bayesian calibration of the 40K decay scheme with implications for 40K-based geochronology
Mantle melting in regions of thick continental lithosphere: Examples from Late Cretaceous and younger volcanic rocks, Southern Rocky Mountains, Colorado (USA) Mantle melting in regions of thick continental lithosphere: Examples from Late Cretaceous and younger volcanic rocks, Southern Rocky Mountains, Colorado (USA)
Deep lithospheric controls on surface deformation and seismicity around the East Anatolian Fault Zone and A3 Triple Junction Deep lithospheric controls on surface deformation and seismicity around the East Anatolian Fault Zone and A3 Triple Junction
Paleogene sedimentary basin development in southern Nevada, USA Paleogene sedimentary basin development in southern Nevada, USA
The Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite The Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite
Kesem-Kebena-Dulecha study area, Ethiopia Kesem-Kebena-Dulecha study area, Ethiopia
Potassium-39-derived 36Ar production during fission-neutron irradiation and its effect on 40Ar/39Ar ages Potassium-39-derived 36Ar production during fission-neutron irradiation and its effect on 40Ar/39Ar ages
Rare 40K decay with implications for fundamental physics and geochronology Rare 40K decay with implications for fundamental physics and geochronology
First observation of the ground-state electron-capture of 40K First observation of the ground-state electron-capture of 40K
Constraints on near-ridge magmatism using 40Ar/39Ar geochronology of enriched MORB from the 8°20' N seamount chain Constraints on near-ridge magmatism using 40Ar/39Ar geochronology of enriched MORB from the 8°20' N seamount chain
Breaking plates: Creation of the East Anatolian fault, the Anatolian plate, and a tectonic escape system Breaking plates: Creation of the East Anatolian fault, the Anatolian plate, and a tectonic escape system
Community for data integration 2019 project report Community for data integration 2019 project report
USGS Geochron Database Explorer USGS Geochron Database Explorer
In addition to the USGS National Cooperative Geologic Mapping Program and the Geosciences and Environmental Change Science Center, below are partners associated with this project.
This project supports the USGS argon geochronology laboratory in Denver. The USGS 40Ar/39Ar geochronology laboratory is a state-of-the-art research facility for determining absolute ages of minerals and rocks. The 40Ar/39Ar laboratory contributes critical geochronology to individual USGS research projects and to partners in academia and other Federal agencies. This laboratory develops methodology for small and difficult sample analysis often at the limits of existing mass spectrometer technology.
Science Issue and Relevance
The 40Ar/39Ar Method: 40Ar/39Ar geochronology is an experimentally robust and versatile method for constraining the age and thermal history of rocks. Such information is extremely valuable for understanding a variety of geological processes including the formation of ore deposits, mountain building and history of volcanic events, paleo-seismic events, and paleo-climate. The 40Ar/39Ar isotopic dating method has evolved into the most commonly applied geochronological method, and can be applied to many geological problems that require precise and accurate time and temperature control.
Methodology to Address Issue
This project provides partial support for the USGS argon geochronology laboratory in Denver. The USGS 40Ar/39Ar geochronology laboratory is a state-of-the-art research facility for determining absolute ages of minerals and rocks. The 40Ar/39Ar laboratory contributes critical geochronology to individual USGS research projects and to partners in academia and other Federal agencies. This facility houses necessary equipment for sample preparation and analysis, including high-sensitivity noble gas mass spectrometers and ultraviolet (UV) and infrared (IR) lasers. The versatility of the 40Ar/39Ar method permits determining the timing of processes and events such as igneous intrusions and extrusions, ore mineralization and hydrothermal fluid circulation, metamorphic cooling and exhumation, mineral formation and recrystallization, and shallow crustal faulting. Scientists are dependent on the geochronologist for data and interpretations to determine these parameters. This laboratory develops methodology for small and difficult sample analysis often at the limits of existing mass spectrometer technology.
Below are other science projects associated with this project.
Porphyry Copper Systems of the Boulder batholith, Montana
USGS Geochron: A database of USGS geochronological and thermochronological data
Evaluation of Critical Elements in Carbonatites
Geologic Framework of the Intermountain West
Serving the U.S. Geological Survey’s geochronological data
Below are data releases associated with this project. Visit USGS Geochron - a database of geochronologic and thermochronologic dates and data.
Argon data for samples from Kenya and Ethiopia Argon data for samples from Kenya and Ethiopia
Argon Data for samples from the Elkhead and Rabbit Ears Mountains, northern Colorado, USA Argon Data for samples from the Elkhead and Rabbit Ears Mountains, northern Colorado, USA
U-Pb detrital zircon data and Ar feldspar data from middle Cenozoic sandstones and volcanic tuffs from southern Nevada, USA U-Pb detrital zircon data and Ar feldspar data from middle Cenozoic sandstones and volcanic tuffs from southern Nevada, USA
Argon data for enriched MORB from the 8°20' N seamount chain Argon data for enriched MORB from the 8°20' N seamount chain
Quetrupillán Volcanic Complex, southern Chile: Argon age data and Pb, Sr, and Nd isotopic data Quetrupillán Volcanic Complex, southern Chile: Argon age data and Pb, Sr, and Nd isotopic data
Argon and SHRIMP-RG Data for Magmatic Steam Alunite, Sericite, and Zircon from Alunite Ridge and Deer Trail Mountain, Marysvale, Utah Argon and SHRIMP-RG Data for Magmatic Steam Alunite, Sericite, and Zircon from Alunite Ridge and Deer Trail Mountain, Marysvale, Utah
USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data (ver. 4.0, May 2025) USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data (ver. 4.0, May 2025)
Argon data for HD-B1 intercalibration Argon data for HD-B1 intercalibration
Argon data for Santa Cruz Basin (ver. 1.1, November 2022) Argon data for Santa Cruz Basin (ver. 1.1, November 2022)
Argon data for Hugub Area, Kesem-Kebena-Dulecha, Ethiopia Argon data for Hugub Area, Kesem-Kebena-Dulecha, Ethiopia
Argon data for Klamath Mountains Argon data for Klamath Mountains
Argon data for Nepal Argon data for Nepal
Using the potassium-argon laser experiment (KArLE) to date ancient, low-K chondritic meteorites Using the potassium-argon laser experiment (KArLE) to date ancient, low-K chondritic meteorites
Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado
Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado
Geologic map of the upper Arkansas River valley region, north-central Colorado Geologic map of the upper Arkansas River valley region, north-central Colorado
Geologic map of the Rio Rico and Nogales 7.5’ quadrangles, Santa Cruz County, Arizona Geologic map of the Rio Rico and Nogales 7.5’ quadrangles, Santa Cruz County, Arizona
Geologic map of the Sunshine 7.5' quadrangle, Taos County, New Mexico Geologic map of the Sunshine 7.5' quadrangle, Taos County, New Mexico
Geologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado Geologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado
Geologic map of the Harvard Lakes 7.5' quadrangle, Park and Chaffee Counties, Colorado Geologic map of the Harvard Lakes 7.5' quadrangle, Park and Chaffee Counties, Colorado
Below are publications associated with this project.
Bayesian calibration of the 40K decay scheme with implications for 40K-based geochronology Bayesian calibration of the 40K decay scheme with implications for 40K-based geochronology
Mantle melting in regions of thick continental lithosphere: Examples from Late Cretaceous and younger volcanic rocks, Southern Rocky Mountains, Colorado (USA) Mantle melting in regions of thick continental lithosphere: Examples from Late Cretaceous and younger volcanic rocks, Southern Rocky Mountains, Colorado (USA)
Deep lithospheric controls on surface deformation and seismicity around the East Anatolian Fault Zone and A3 Triple Junction Deep lithospheric controls on surface deformation and seismicity around the East Anatolian Fault Zone and A3 Triple Junction
Paleogene sedimentary basin development in southern Nevada, USA Paleogene sedimentary basin development in southern Nevada, USA
The Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite The Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite
Kesem-Kebena-Dulecha study area, Ethiopia Kesem-Kebena-Dulecha study area, Ethiopia
Potassium-39-derived 36Ar production during fission-neutron irradiation and its effect on 40Ar/39Ar ages Potassium-39-derived 36Ar production during fission-neutron irradiation and its effect on 40Ar/39Ar ages
Rare 40K decay with implications for fundamental physics and geochronology Rare 40K decay with implications for fundamental physics and geochronology
First observation of the ground-state electron-capture of 40K First observation of the ground-state electron-capture of 40K
Constraints on near-ridge magmatism using 40Ar/39Ar geochronology of enriched MORB from the 8°20' N seamount chain Constraints on near-ridge magmatism using 40Ar/39Ar geochronology of enriched MORB from the 8°20' N seamount chain
Breaking plates: Creation of the East Anatolian fault, the Anatolian plate, and a tectonic escape system Breaking plates: Creation of the East Anatolian fault, the Anatolian plate, and a tectonic escape system
Community for data integration 2019 project report Community for data integration 2019 project report
USGS Geochron Database Explorer USGS Geochron Database Explorer
In addition to the USGS National Cooperative Geologic Mapping Program and the Geosciences and Environmental Change Science Center, below are partners associated with this project.