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A hydrocarbon pipeline is under construction outside the city of Hermosillo, Sonora, Mexico. Before construction of the pipeline begins, both surficial and subsurface archeological reconnaissance work must be carried along the footprint of the hydrocarbon pipeline. This site contains surficial archeological remains identified as lithic reductions sites by archeologists from the National Institute of Anthropology and History (INAH)-Sonora Center. Lithic reduction sites were once stone-tool manufacturing sites used by ancient natives. The main objective of this pseudo three-dimensional (3D) Electrical Resistivity Imaging (ERI) survey was to identify potential major archeological remains within the near subsurface that could affect the construction of the hydrocarbon pipeline.
To map sharply changing geology and soil types with unknown depth and orientation below ground in flat or rugged terrain with direct application to archeological reconnaissance, civil engineering, geotechnical, water exploration, environmental, and mineral exploration projects.
The pseudo-3D ERI survey was carried on February 8th of 2017. It consists of three parallel two-dimensional Dipole-Dipole arrays collected with a SuperSting™ R8 WiFi, a Switchbox R8, and a set of the FlexLite Passive land cables with 28 electrodes spaced at 2m intervals. The in-line spacing was 4m. The parallel transects were combined and processed in AGI EarthImager™ 3D software to create a pseudo-3D inverted resistivity model. The survey site was located in the outskirts of Hermosillo, Sonora, Mexico. The site surface conditions consisted of geomorphologically stable Pleistocene alluvium, which yield favorable contact resistance conditions.
The pseudo-3D Dipole-Dipole survey successfully imaged the subsurface extend of the two exposed lithic reduction sites. In the 3D inverted resistivity models, the lithic reduction sites show up as high resistivity anomalies within unlithified Pleistocene fluvial deposits, which shown as low resistivity anomalies. The pseudo-3D inverted resistivity model does not reveal the presence of major archeological remains that could compromise the construction of this important hydrocarbon pipeline.
Watch the video of this case history.
Specially designed tools: These rugged instruments are useful for work in all kinds of terrain and topography including borehole and marine settings.