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Audiomagnetotelluric Data and Preliminary Two-Dimensional Models from Spring, Dry Lake, and Delamar Valleys, Nevada

Open-File Report 2008-1301

Prepared in cooperation with the Southern Nevada Water Authority (SNWA)
By:
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Abstract

This report presents audiomagnetotelluric (AMT) data along fourteen profiles in Spring, Delamar, and Dry Lake Valleys, and the corresponding preliminary two-dimensional (2-D) inverse models. The AMT method is a valuable tool for estimating the electrical resistivity of the Earth over depth ranges from a few meters to less than one kilometer, and it is important for revealing subsurface structure and stratigraphy within the Basin and Range province of eastern Nevada, which can be used to define the geohydrologic framework of the region. We collected AMT data by using the Geometrics StrataGem EH4 system. Profiles were 0.7 - 3.2 km in length with station spacing of 50-400 m. Data were recorded in a coordinate system parallel to and perpendicular to the regional geologic-strike direction with Z positive down. We show AMT station locations, sounding curves of apparent resistivity, phase, and coherency, and 2-D models of subsurface resistivity along the profiles. The 2-D inverse models are computed from the transverse electric (TE), transverse magnetic (TM), and TE+TM mode data by using a conjugate gradient, finite-difference method. Preliminary interpretation of the 2-D models defines the structural framework of the basins and the resistivity contrasts between alluvial basin-fill, volcanic units, and carbonate basement rocks.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Audiomagnetotelluric Data and Preliminary Two-Dimensional Models from Spring, Dry Lake, and Delamar Valleys, Nevada
Series title:
Open-File Report
Series number:
2008-1301
Edition:
Version 1.0
Year Published:
2008
Language:
ENGLISH
Publisher:
Geological Survey (U.S.)
Contributing office(s):
U.S. Geological Survey
Description:
Report: 59 p.; Appendix
Online Only (Y/N):
Y