Airborne electromagnetic, magnetic, and radiometric survey of the Mississippi Alluvial Plain, November 2019 - March 2020

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired November 2019 to March 2020 along 24,030 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP).  Data were acquired by CGG Canada Services, Ltd. with three different airborne sensors: the CGG Canada Services, Ltd. TEMPEST time-domain AEM instrument that is used to map subsurface geologic structure at depths up to 300 meters (m), depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 centimeters that is used to determine differences in soil constituents. The survey was flown at a nominal sensor flight height of 120 m above terrain with 6-kilometer spaced east-west flight lines. The main survey block covers 22,250 line-km. The Mississippi River and the Arkansas River were surveyed along their center axes, covering 1,225 line-km (flight line numbers 500101 and 700201-700206 nonsuccessive), and three separate inset grids were flown: (1) Ozark basement reconnaissance lines with variable line spacing for a total of 234 line-km (flight line numbers 400801-401401 nonsuccessive), (2) Shellmound focus area in Mississippi with 250 m line spacing for a total of 485 line-km (flight line numbers 604501-608101 nonsuccessive), and (3) New Madrid Seismic Zone focus area in Missouri and Tennessee with variable line spacing for a total of 161 line-km (flight line numbers 710101-710401 nonsuccessive). 91-series lines are repeat test-lines flown periodically throughout the survey, with one repeat line established for each base station. 902- and 905-series lines are ~60 second high-altitude datasets collected pre- and post- flight, respectively, to evaluate the system out of ground-response. 
This data release includes minimally processed (raw) AEM data as supplied by CGG Canada Services, Ltd. (https://www.sciencebase.gov/catalog/item/5f4e951882ce4c3d1233cb7d), the fully processed (downsampled by averaging) sounding data (https://www.sciencebase.gov/catalog/item/5f4e953482ce4c3d1233cb82), and inverted resistivity depth sections along all flight lines (https://www.sciencebase.gov/catalog/item/5f4e954682ce4c3d1233cb84), as well as unprocessed and processed (following International Atomic Energy Agency Technical Report procedures) radiometric data as supplied by CGG Canada Services, Ltd. (https://www.sciencebase.gov/catalog/item/5f4e951882ce4c3d1233cb7d). Data acquisition and minimal processing was conducted by CGG Canada Services, Ltd. and described in detail in the contractor's report. Digital data from production flights are provided in ASEG-GDF2 format, an ASCII format geophysical data standard that uses a self-describing collection of files to allow data to be automatically identified and read by a computer application. Data fields in the data file (.DAT) are defined in the associated definition file (.DFN). Please see the ReadME included in this data release for a description of how to interpret the .DFN files or visit https://www.aseg.org.au/sites/default/files/pdf/ASEG-GDF2-REV4.pdf for more information on the ASEG-GDF2 standard.

Tags: aeromagnetic-surveying, aeroradiometric-surveying, arkansas, arkansas-river, electromagnetic-surveying, electromagnetics, engineering-sciences, environment, geologic-structure, geology-geophysics-and-geochemistry-science-center, geophysics, geoscientificinformation, geospatial-datasets, gggsc, groundwater, hydrogeology, hydrology, illinois, louisiana, magnetic-field, magnetics, mississippi, mississippi-alluvial-plain, mississippi-river, mississippi-river-valley-alluvial-aquifer, missouri, mrva, new-madrid-seismic-zone, potassium, radiometrics, resistivity, shellmound, tennessee, thorium, u-s-geological-survey, uranium, usgs, usgs-5f35b17382cee144fb35a733, water-availability-and-use-science-program, water-resources, wausp
Organization: Department of the Interior