Airborne electromagnetic, magnetic, and radiometric survey of the Mississippi Alluvial Plain, Mississippi Embayment, and Gulf Coastal Plain, September 2021 - January 2022

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired September 2021 to January 2022 along 27,204 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP), Mississippi Embayment, and Gulf Coastal Plain.  Data were acquired by Xcalibur Multiphysics (Canada), Ltd. with three different airborne sensors: the 30Hz 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 300 and 600 km (nominal) spaced east-west flight lines. The main survey block covers 24,654 line-km. The Chicot aquifer focus area was surveyed along 360 line-km (flight numbers 2900101-2900421 nonsuccessive). The Mississippi River and the Atchafalaya River were surveyed along their center axes, covering 742 line-km (flight line numbers 6004001-6004003 and 5002001-5002002). Two separate inset grids were flown: (1) University of Memphis (UMemphis) focus area lines with 500 m line spacing for a total of 1260 line-km (flight line numbers 1000301-1030001 nonsuccessive), and (2) Hot Springs focus area with 350 m line spacing for a total of 188 line-km (flight line numbers 2001001-2027001 nonsuccessive). 
91-series lines are repeat test-lines flown periodically throughout the survey, with one repeat line established for each base station. 901- and 904-series lines are flown under standard survey conditions with the transmitter on and the receiver off to evaluate the noise contribution from the acquisition system pre- and post- flight, respectively. 902- and 905-series lines are ~60 second high-altitude datasets collected to evaluate the system out of ground-response pre- and post- flight, respectively. 903-series lines are 30-40 second 'swoop' datasets to confirm correct operation of the system during variable pitch manoeuvres. 906-series lines are flown under standard survey conditions with the transmitter off and the receiver on to evaluate the ambient noise in the system.
AEM data were inverted using 1-D inversion to produce models of electrical resistivity along flight paths.

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-62ffc245d34e37cba73e1fa0, water-availability-and-use-science-program, water-resources, wausp
Organization: Department of the Interior