<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Denys Grombacher</dc:contributor>
  <dc:contributor>John W. Lane</dc:contributor>
  <dc:contributor>Johan Lind</dc:contributor>
  <dc:contributor>Esben Auken</dc:contributor>
  <dc:creator>Pradip Kumar Maurya</dc:creator>
  <dc:date>2022</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;For several decades, induced polarization (IP) effects on transient electromagnetic (TEM) responses have been observed. These effects can manifest as late-time negative transients or as rapidly decaying curves and are usually associated with highly polarizable bodies. If neglected, IP effects can lead to erroneous resistivity models. Recent work allows IP effects to be incorporated into the inversion of TEM data on a more routine basis. In a recent field survey in western Tanzania, strongly IP-affected TEM signals are observed using a towed-transient electromagnetic (tTEM) system. The survey have been carried out to locate drinking water resources in a weathered regolith setting. In these settings, an inversion of tTEM data using a resistivity-only forward model (i.e.,&amp;nbsp;IP neglected) cannot fit the data and severely limits the value of the TEM data for hydrogeologic interpretation. To account for IP effects, we have applied a modified version of the Cole-Cole model called the maximum phase angle (MPA) model to invert IP-affected tTEM data. The MPA model incorporates four inversion model parameters: resistivity (&lt;/span&gt;&lt;span class="inline-formula no-formula-id"&gt;⁠&lt;i&gt;&lt;span id="MathJax-Element-1-Frame" class="MathJax" data-mathml="&lt;math xmlns=&amp;quot;http://www.w3.org/1998/Math/MathML&amp;quot;&gt;&lt;mrow xmlns=&amp;quot;&amp;quot;&gt;&lt;mi&gt;&amp;amp;#x3C1;&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;"&gt;&lt;span id="MathJax-Span-1" class="math"&gt;&lt;span&gt;&lt;span id="MathJax-Span-2" class="mrow"&gt;&lt;span id="MathJax-Span-3" class="mrow"&gt;&lt;span id="MathJax-Span-4" class="mi"&gt;ρ&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;/span&gt;&lt;span&gt;), MPA (&lt;/span&gt;&lt;span class="inline-formula no-formula-id"&gt;⁠&lt;span id="MathJax-Element-2-Frame" class="MathJax" data-mathml="&lt;math xmlns=&amp;quot;http://www.w3.org/1998/Math/MathML&amp;quot;&gt;&lt;mrow xmlns=&amp;quot;&amp;quot;&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;&amp;amp;#x3D5;&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;max&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;"&gt;&lt;span id="MathJax-Span-5" class="math"&gt;&lt;span&gt;&lt;span id="MathJax-Span-6" class="mrow"&gt;&lt;span id="MathJax-Span-7" class="mrow"&gt;&lt;span id="MathJax-Span-8" class="msub"&gt;&lt;i&gt;&lt;span id="MathJax-Span-9" class="mrow"&gt;&lt;span id="MathJax-Span-10" class="mi"&gt;ϕ&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;sub&gt;&lt;span id="MathJax-Span-11" class="mrow"&gt;&lt;span id="MathJax-Span-12" class="mi"&gt;max&lt;/span&gt;&lt;/span&gt;&lt;/sub&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;sub&gt;⁠&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;), relaxation time (&lt;/span&gt;&lt;span class="inline-formula no-formula-id"&gt;⁠&lt;i&gt;&lt;span id="MathJax-Element-3-Frame" class="MathJax" data-mathml="&lt;math xmlns=&amp;quot;http://www.w3.org/1998/Math/MathML&amp;quot;&gt;&lt;mrow xmlns=&amp;quot;&amp;quot;&gt;&lt;mi&gt;&amp;amp;#x3C4;&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;"&gt;&lt;span id="MathJax-Span-13" class="math"&gt;&lt;span&gt;&lt;span id="MathJax-Span-14" class="mrow"&gt;&lt;span id="MathJax-Span-15" class="mrow"&gt;&lt;span id="MathJax-Span-16" class="mi"&gt;τ&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;/span&gt;&lt;span&gt;), and frequency exponent (&lt;/span&gt;&lt;span class="inline-formula no-formula-id"&gt;⁠&lt;i&gt;&lt;span id="MathJax-Element-4-Frame" class="MathJax" data-mathml="&lt;math xmlns=&amp;quot;http://www.w3.org/1998/Math/MathML&amp;quot;&gt;&lt;mrow xmlns=&amp;quot;&amp;quot;&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;"&gt;&lt;span id="MathJax-Span-17" class="math"&gt;&lt;span&gt;&lt;span id="MathJax-Span-18" class="mrow"&gt;&lt;span id="MathJax-Span-19" class="mrow"&gt;&lt;span id="MathJax-Span-20" class="mi"&gt;c&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;/span&gt;&lt;span&gt;). The MPA model fits the data well and improves the reliability of the resistivity model. In much of the surveyed region, the inverted models using MPA display a three-layer system consisting of an upper resistive laterite layer of varying thickness and an intermediate polarizable conductive unit overlying more resistive weathered basement rocks. The conductive polarizable layer is interpreted as a chemically weathered saprolite separating the surficial and deeper aquifers. Overall, tTEM inversion results provide a local understanding of groundwater systems, especially in such regions with very limited subsurface knowledge.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1190/geo2021-0396.1</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Society of Exploration Geophysics</dc:publisher>
  <dc:title>Inversion of induced polarization-affected towed-transient electromagnetic data in a lateritic regolith geology: A case study from western Tanzania</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>