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Airborne electromagnetic and magnetic survey data of the San Juan-Silverton Caldera complex, Silverton, Colorado, 2019

September 2, 2020

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) 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). Minimally processed data from production flights are provided and described in the data dictionary and contractor's report. The complete data package received from the contractor is included in a separate zip-file directory and described in the contractor's report. This data release provides minimally processed data only as provided by the contractor. Reference: U.S. Geological Survey, The National Map, 2019, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed April 2019 at