Preliminary Results From The First Airborne EM Survey Conducted In Yellowstone National Park
K. Dickey, W.S. Holbrook, C. Finn, E. Auken, B. Carr, K. Sims, P. Bedrosian, J. Lowenstern, S. Hurwitz and J. Pedersen
Event name: 23rd European Meeting of Environmental and Engineering Geophysics
Session: Best of SAGEEP
Publication date: 03 September 2017
Info: Extended abstract, PDF ( 153.46Kb )
Price: € 20
Yellowstone National Park hosts over 10,000 thermal features (e.g. geysers, fumaroles, mud pots, and hot springs), yet little is known about the circulation depth of meteoric water feeding these features, the pathways that guide deep, hot fluids to the surface, or the separation depth of the steam that sources vapor-dominated systems. Previous near-surface geophysical studies have been effective in imaging shallow hydrothermal pathways in some areas of the park, but these methods are difficult to conduct over the large areas needed to characterize entire hydrothermal systems. Transient electromagnetic (TEM) soundings and 2D direct current (DC) resistivity profiles show that hydrothermal fluids at active sites have a higher electrical conductivity than the surrounding hydrothermally inactive areas. For that reason, airborne TEM should be an effective method to characterize large areas and identify hydrothermally active and inactive zones using electrical conductivity. Here we present preliminary results from an airborne transient electromagnetic (TEM) and magnetic survey acquired jointly by the U.S. Geological Survey (USGS) and the University of Wyoming (UW) in November 2016. The survey covers 2600 line-km of data at two scales: regional surveys with lines spaced 450 apart and three smaller, high-resolution surveys with line spacing of 150 m. The regional survey will cover northern Yellowstone Lake, the Norris-Mammoth corridor, and the Upper Geyser basin. The high-resolution surveys focus on the Upper Geyser Basin (including Old Faithful), the Norris Geyser Basin, and the Mud Volcano Area. Data was acquired with the SkyTEM 312, with a magnetic moment of 0.5 M A-m2. We will present preliminary inversions using the Aarhus Workbench software, with particular focus on the depths of vapor phase separation and the connectivity of pathways of meteoric water recharge.