Surface geophysical surveys were conducted in July 2017 in the greater East River Watershed near Crested Butte Colorado with a focused effort in Redwell Basin as part of a broader study of the role of bedrock groundwater in the hydrogeology of mineralized mountain watersheds. Ten gravity stations were acquired with a LaCoste and Romberg G-model relative gravimeter to map density variations. This data release includes principal facts for the gravity stations provided as digital data. Data fields are defined in the data dictionary.

Surface electrical resistivity tomography (ERT), magnetic, and gravity surveys were conducted in July 2017 in the greater East River Watershed near Crested Butte Colorado with a focused effort in Redwell Basin as part of a broader study of the role of bedrock groundwater in the hydrogeology of mineralized mountain watersheds. Five electrical resistivity tomography profiles were acquired within Redwell Basin and Brush Creek to map geologic structure at depths up to 40 meters, depending on the subsurface resistivity, using the Advanced Geosciences, Inc. SuperSting R8 resistivity meter. This data release includes the raw and processed resistivity data as well as inverted resistivity models. All are provided as digital data, and data fields for each file type are defined in the respective data dictionary.

Surface electrical resistivity tomography (ERT), magnetic, and gravity surveys were conducted in July 2017 in the greater East River Watershed near Crested Butte Colorado with a focused effort in Redwell Basin as part of a broader study of the role of bedrock groundwater in the hydrogeology of mineralized mountain watersheds. Five electrical resistivity tomography profiles were acquired within Redwell Basin and Brush Creek to map geologic structure at depths up to 40 meters, depending on the subsurface resistivity, using the Advanced Geosciences, Inc. SuperSting R8 resistivity meter. This data release includes the raw and processed resistivity data as well as inverted resistivity models. All are provided as digital data, and data fields for each file type are defined in the respective data dictionary.

Geophysical measurements and related field data were collected by the U.S. Geological Survey (USGS) at the Alaska Peatland Experiment (APEX) site in Interior Alaska from 2018 to 2020 to characterize subsurface thermal and hydrologic conditions along a permafrost thaw gradient. The APEX site is managed by the Bonanza Creek LTER (Long Term Ecological Research). Nine instrument monitoring sites (APEX1-APEX9) were established in April 2018. To quantify permafrost and thaw zone characteristics along the instrumented gradient, electrical resistivity tomography (ERT) data were collected in August 2018 along four 82 meter (m)-long transects between select sites: APEX1-3, APEX5-3, APEX5-7, and APEX6-8. Data were collected for both dipole-dipole (DD) and inverse Schlumberger (IS) survey geometries. Inverted models of electrical resistivity were produced from the separate DD and IS datasets, as well as the combination of both datasets inverted jointly (labeled DDIS). The resulting models of electrical resistivity revealed the spatial variability in soil lithology and thermal state (frozen vs. thawed) to depths up to 10-15 m below the surface. Manual permafrost-probe measurements of thaw depths were collected at set intervals along each ERT transect and used for comparison to the resistivity models.

In June 2017, U.S. Geological Survey (USGS) collected geophysical measurements to help map variations in electrical properties to infer shallow flowpaths and storage zones influenced by residual spilled unconventional oil and gas (UOG). Two survey profiles were collected, each including dipole-dipole and Wenner-Schlumberger configurations. For each survey a total of 56 electrodes spaced 1.0 meter (m) apart were used. During the ERT measurement, current is injected through two current electrodes and voltage is measured sequentially across multiple pairs of potential electrodes; the known current and the measured voltages are used to determine the apparent resistivity of the subsurface. Inverse modeling of ERT survey results provide profiles of resistivity that can be interpreted for subsurface layers. This data release provides the raw ERT data and output from inversion.

This data release consists of 1,984 line-kilometers of airborne electromagnetic (AEM), magnetic data and radiometric data collected from October to November 2017 in the upper East River and surrounding watersheds in central Colorado. The U.S. Geological Survey contracted Geotech Ltd. to acquire these data as part of regional investigations into the geologic structure and hydrologic framework of the area. The AEM data have been inverted to produce a series of regional cross-sections that constrain the electrical properties of the subsurface to a depth of ~500m. Data were acquired using the VTEM ET time-domain helicopter-borne electromagnetic system along flight lines that cross important geological structures over a 483 square kilometer area. In addition to magnetic and radiometric data, this data release includes minimally processed AEM data, processed AEM data used in the development of resistivity and induced polarization (IP) models, and laterally constrained inverse models for resistivity and IP parameters along all flight lines. Data that intersected cultural infrastructure have been removed from the processed AEM data prior to inversion.

This data release consists of 1,984 line-kilometers of airborne electromagnetic (AEM), magnetic data and radiometric data collected from October to November 2017 in the upper East River and surrounding watersheds in central Colorado. The U.S. Geological Survey contracted Geotech Ltd. to acquire these data as part of regional investigations into the geologic structure and hydrologic framework of the area. The AEM data have been inverted to produce a series of regional cross-sections that constrain the electrical properties of the subsurface to a depth of ~500m. Data were acquired using the VTEM ET time-domain helicopter-borne electromagnetic system along flight lines that cross important geological structures over a 483 square kilometer area. In addition to magnetic and radiometric data, this data release includes minimally processed AEM data, processed AEM data used in the development of resistivity and induced polarization (IP) models, and laterally constrained inverse models for resistivity and IP parameters along all flight lines. Data that intersected cultural infrastructure have been removed from the processed AEM data prior to inversion.