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2007 GSA Denver Annual Meeting (28–31 October 2007)

Paper No. 7
Presentation Time: 9:40 AM

USING GEOPHYSICS AND STEREOGRAPHIC 3D VISUALIZATION TO IMPROVE CONCEPTUAL MODELS


SICKBERT, Timothy B., Boone Pickens School of Geology, Oklahoma State University, 105 Noble Research Center, Stillwater, OK 74078-3031, HALIHAN, Todd, School of Geology, Oklahoma State University, 105 NRC, OSU, Stillwater, OK 74078, PETERSON, Eric W., Geography - Geology, Illinois State University, Campus Box 4400, Normal, IL 61790 and VAN DER HOVEN, Stephen J., Department of Geography-Geology, Illinois State University, Campus Box 4400, Normal, IL 61790, tim.sickbert@okstate.edu

Electrical-resistivity imaging (ERI) conducted at the Illinois State University Randolph Well Field (ISU-RWF) have provided time- and cost-effective data revealing complexities not apparent from numerous borings and pumping tests. 2D and projected 3D maps of combined surficial, borehole, and geophysical data are either spatially disconnected or overwhelming due to the quantity of data. Stereographic 3D computer software and display systems integrate these data into comprehensible models. ERI—or other geophysical data—along with stereographic 3D visualization tools support more complete conceptual models and help to focus ongoing and future research.

The ISU-RWF is a research and instructional well field adjacent to Little Kickapoo Creek in an outwash valley among Wisconsinin recessional moraines. Numerous boreholes ranging from 7 to 15m consistently indicated a layer-cake stratigraphy with only minor relief at the contacts between the uppermost alluvium, the underlying outwash, and the basal lodgement till. Aquifer pumping-tests and water-table mapping suggested an homogeneous, laterally extensive outwash aquifer hydraulically integrated with the surface stream. However, ERI data from 2000 m of lines within an area of about 13 hectares to a maximum depth of about 50 m revealed considerable relief on the outwash-till surface, which was later confirmed by targeted drilling. Features that are interpreted to be buried valleys, oxbows, and isolated abandoned channels are present. Stereographic 3D visualization tools reveal spatial and suggest geomorphic relationships among these features.

Integrating ERI, surficial, and well-log data into geological/geospatial software supporting stereographic 3D visualization has enhanced our conceptual model of ISU-RWF. This knowledge has direct applications for improving numerical flow and transport models of the site, and to ongoing research into surface water-groundwater exchange and nutrient cycling.

Session No. 193

T41. High-Resolution Geophysical Methods for Hydrogeologic Site Characterization
Wednesday, 31 October 2007: 8:00 AM-12:00 PM
Geological Society of America Abstracts with Programs. Vol. 39, No. 6, p.520
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