Near-surface geophysical data from within the Bonita Peak Mining District in Silverton, Colorado, USA are presented. These data were collected in 2019. The data include fiber optic distributed temperature sensing (FO-DTS) and frequency domain electromagnetic induction (FDEM) data collected in and around roughly 1 km reaches of Cement Creek and California Gulch. Additional data, including ground penetrating radar (GPR) and self potential (SP), were gathered from a peatland that intercepts acid mine drainage from Mogul Mine into Cement Creek. The peatland is located off the eastern bank of Cement Creek in the northern portion of the reach surveyed with FO-DTS and FDEM. In 2021, an FO-DTS, FDEM, and magnetometer (MAG) dataset were collected along both banks of an approximate 3-4 km reach of the Animas River, spanning from Arrastra Gulch upstream to USGS gage 09358000.

This child item contains fiber-optic distributed temperature sensing (FO-DTS) data collected along the streambed interface of two streams named Cement Creek and California Gulch Creek, as well as the Animas River, located near Silverton Colorado. The FO-DTS method utilizes the temperature-dependent backscatter of light pulses emitted along armored fiber-optic cables to evaluate temperature at discrete linear sampling locations. For these deployments a Salixa XT-DTS control unit (Salixa Ltd, Hertfordshire, UK) was used, and measurements were made over several day increments at 0.508 m linear resolution along the streambed interface. Specific locations for collected data are located within the data files, and additional details are contained in the ‘readme’ files within each zip data directory.

Airborne electromagnetic (AEM) and magnetic survey data were collected during April and May 2019 along 1,467 line-kilometers in the San Juan-Silverton Caldera complex, Colorado, in the Southern Rocky Mountain Volcanic Field. Data were acquired by Geotech, Ltd. with the versatile time-domain electromagnetic (VTEM-ET) system together with a Geometrics optically pumped cesium vapor magnetometer. The survey was flown at a mean flight height of 140 meters (m) above terrain in various line directions and line spacings ranging from 150 m to 600 m. Multiple variable-spaced lines were flown along rivers and streams in the survey area. USGS provided the contractor with the San Juan National Forest Lidar Point Cloud elevation dataset imported from the USGS National MAP 3D Elevation Program (U.S. Geological Survey, 2019). AEM data were inverted to produce models of electrical resistivity along flight paths. References: U.S. Geological Survey, The National Map, 2019, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed April 2019 at https://nationalmap.gov/3DEP/3dep_prodserv.html First posted September 16, 2020 Revised August 19, 2022, ver.2.0 Changes in version 2.0: 1. Updated contractor package and raw data to remediate an erroneous calculation of transmitter/receiver altitude. 2. Converted dataset to netCDF format. 3. Added inverted resistivity models for the entire dataset.

This child item contains self-potential (SP) data collected over a small alpine wetland between Mogul Mine and Cement Creek located near Silverton, Colorado. Mine-impacted water is transported to Cement Creek via surface channels and groundwater through this wetland. The SP method measures passive voltages in the subsurface using a high impedance voltmeter with one fixed electrode at a base station and one mobile electrode. Strong self-potential anomalies have been associated with ore bodies and sharp redox fronts. Data were collected with an Agilent U1252B multimeter with STELTH3 Ag-AgCl Model SRE-011-SPB porous pot electrodes. Additional details are contained in the ‘readme.txt’ file within this directory.

This child item contains self-potential (SP) data collected over a small alpine wetland between Mogul Mine and Cement Creek located near Silverton, Colorado. Mine-impacted water is transported to Cement Creek via surface channels and groundwater through this wetland. The SP method measures passive voltages in the subsurface using a high impedance voltmeter with one fixed electrode at a base station and one mobile electrode. Strong self-potential anomalies have been associated with ore bodies and sharp redox fronts. Data were collected with an Agilent U1252B multimeter with STELTH3 Ag-AgCl Model SRE-011-SPB porous pot electrodes. Additional details are contained in the ‘readme.txt’ file within this directory.

Acid mine drainage (AMD) can cause ecological harm throughout the state of Colorado, including in the Upper Animas River watershed near Silverton. In the Upper Animas River watershed, a technique that includes the emplacement of hydraulic bulkheads within draining mines has been used to remediate AMD. Data for major ions and trace metal concentrations, isotopic compositions, and discharge from streams, draining mines, and springs were compiled for a period of approximately 30 years to better understand the processes occurring during the impoundment of water within underground mine workings and to define spatial extent of groundwater connectivity. These datasets were evaluated using statistical and geochemical modeling approaches.

Acid mine drainage (AMD) can cause ecological harm throughout the state of Colorado, including in the Upper Animas River watershed near Silverton. In the Upper Animas River watershed, a technique that includes the emplacement of hydraulic bulkheads within draining mines has been used to remediate AMD. Data for major ions and trace metal concentrations, isotopic compositions, and discharge from streams, draining mines, and springs were compiled for a period of approximately 30 years to better understand the processes occurring during the impoundment of water within underground mine workings and to define spatial extent of groundwater connectivity. These datasets were evaluated using statistical and geochemical modeling approaches.

This dataset includes magnetotelluric (MT) sounding data collected in July 2019 in the Silverton Caldera complex, Colorado, in the Southern Rocky Mountain Volcanic Field, by the U.S. Geological Survey (USGS). Along with geologic mapping, airborne magnetics, airborne electromagnetics, and audiomagnetotellurics, the USGS collected MT data at 24 sites along five profiles ranging from 2 to 5 kilometers in length: across Red Mountain of the Silverton caldera, within the caldera in Eureka Graben, across the south-eastern margin of the caldera along Arrastra Gulch, across the southern margin of the caldera along the western margin of Kendall Mountain, and across the south-western margin of the caldera along South Fork Mineral Creek.

This dataset includes magnetotelluric (MT) sounding data collected in July 2019 in the Silverton Caldera complex, Colorado, in the Southern Rocky Mountain Volcanic Field, by the U.S. Geological Survey (USGS). Along with geologic mapping, airborne magnetics, airborne electromagnetics, and audiomagnetotellurics, the USGS collected MT data at 24 sites along five profiles ranging from 2 to 5 kilometers in length: across Red Mountain of the Silverton caldera, within the caldera in Eureka Graben, across the south-eastern margin of the caldera along Arrastra Gulch, across the southern margin of the caldera along the western margin of Kendall Mountain, and across the south-western margin of the caldera along South Fork Mineral Creek.

Multiple sources of mine drainage including discharge from the abandoned Dinero mine tunnel and two gulches flow into a wetland, known herein as the Dinero wetland along the Lake Fork Creek corridor. The Dinero wetland is approximately 20 acres in extent. The Dinero wetland is being considered as a location for passive treatment of the mine drainage flowing through it. As such, study objectives are to understand: (1) variations in pH, specific conductance, and temperature in surface water in the wetland; (2) metal loading into and out of the wetland; (3) the configuration of surface drainage features; (4) the configuration of subsurface conductive features; and (4) depth to bedrock in the wetland. These data will be used to help understand whether the wetland is currently and naturally treating the mine drainage flowing through it and will help pinpoint locations needing additional investigations to help inform potential passive treatment scenarios. Near-surface frequency domain electromagnetic induction (FDEM) data were collected in an alpine wetland downgradient of the Dinero Tunnel mine portal near Leadville Colorado on August 17, 2023 and July 16-17, 2024. FDEM data were collected on foot along an approximate grid pattern with a Geophex GEM-2 Instrument. An EMLID Reach RS2+ base station was established, while a rover antenna receiving real-time kinematic (RTK) corrections was used to transmit GPS positions to the GEM-2 logger. This child item includes the raw and processed data, as well as inverted electrical resistivity models from these surveys.