112-5 Ground-based Geophysics to Amend Previously Interpreted Buried Bedrock Valley Geometry

Session: Geophysics in Investigating and Exploring for Mineral, Energy and Groundwater Resources (Posters)

Poster Booth No.: 239

Presenting Author:

Lani Kiene

Authors:

Kiene, Lani¹, Fanning, Aiden², Ortman, Caleb³, Drager, Lillian⁴, Young, Steven⁵, Balikian, Riley⁶, Thomason, Jason F.⁷, Mwakanyamale-Gilkie, Kisa⁸, Malone, David H.⁹

(1) Illinois State University, Bloomington-Normal, Illinois, USA, (2) Department of Geography & Geology, Illinois State University, Bloomington-Normal, IL, USA, (3) Department of Geography & Geology, Illinois State University, Bloomington-Normal, IL, USA, (4) Illinois State University, Bloomington-Normal, IL, USA, (5) Illinois State Geological Survey, University of Illinois, Champaign, Illinois, USA, (6) Illinois State Geologic Survey, University of Illinois, Champaign, IL, USA, (7) Illinois State Geological Survey, University of Illinois, Champaign, IL, USA, (8) Illinois State Geologic Survey, University of Illinois, Champaign, Illinois, USA, (9) Illinois State University, Bloomington-Normal, IL, USA,

Abstract:

Ground-based geophysics techniques, particularly 2-D electrical resistivity tomography (ERT) and ambient seismic horizontal-to-vertical spectral ratio (HVSR), verify newly acquired helicopter time-domain electromagnetic (HTEM) data intended to map aquifers in northern Illinois. We calibrate and interpret ERT and HVSR data based in part upon descriptions from nearby water well drillers and geologic core descriptions.These calibrations and new interpretations test previous interpretations of a local, deeply incised buried bedrock valley. Profile locations were chosen along the flanks of the main valley and its tributaries to better resolve the overall valley geometry. We collected 183 HVSR points and roughly a mile of ERT data to target these flanks. When possible, ERT and HVSR data were collected at the same site to more accurately establish the stratigraphy and bedrock depth at each location. We show general agreement among the geophysical and geological datasets and we interpret bedrock topography and Quaternary stratigraphy based on these and other datasets. These data have important implications on groundwater resource availability on a regional and local scale.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9916

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