| Title | Bedrock mapping of buried valley networks using seismic reflection and airborne electromagnetic data |
| |
| Author | Oldenborger, G A ;
Logan, C E; Hinton, M J; Pugin, A J -M; Sapia, V; Sharpe, D R; Russell, H A J |
| Source | Journal of Applied Geophysics vol. 128, 2016 p. 191-201, https://doi.org/10.1016/j.jappgeo.2016.03.006 |
| Image |  |
| Year | 2016 |
| Alt Series | Earth Sciences Sector, Contribution Series 20150383 |
| Publisher | Elsevier BV |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Manitoba |
| NTS | 62B/03; 62B/04; 62B/05; 62B/06 |
| Area | Spiritwood |
| Lat/Long WENS | -100.0000 -99.0000 49.5000 49.0000 |
| Subjects | general geology; geophysics; hydrogeology; regional geology; sedimentology; structural geology; surficial geology/geomorphology; magnetic surveys, airborne; seismic reflection surveys; seismic surveys,
ground; seismic exploration; electromagnetic mapping; electromagnetic surveys; water wells; well locations; bedrock geology; conductivity surveys; e m surveys, airborne; bedrock topography; modelling |
| Illustrations | location maps; landsat images; seismic cross-sections; graphs; resistivity maps; seismic maps |
| Program | Groundwater Geoscience Aquifer Assessment & support to mapping |
| Released | 2016 05 01 |
| Abstract | In glaciated terrain, buried valleys often host aquifers that are significant groundwater resources. However, given the range of scales, spatial complexity and depth of burial, buried valleys often
remain undetected or insufficiently mapped. Accurate and thorough mapping of bedrock topography is a crucial step in detecting and delineating buried valleys and understanding formative valley processes. We develop a bedrock mapping procedure
supported by the combination of seismic reflection data and helicopter time-domain electromagnetic data with water well records for the Spiritwood buried valley aquifer system in Manitoba, Canada. The limited spatial density of water well bedrock
observations precludes complete depiction of the buried valley bedrock topography and renders the water well records alone inadequate for accurate hydrogeological model building. Instead, we leverage the complementary strengths of seismic reflection
and airborne electromagnetic data for accurate local detection of the sediment-bedrock interface and for spatially extensive coverage, respectively. Seismic reflection data are used to define buried valley morphology in cross-section beneath survey
lines distributed over a regional area. A 3D model of electrical conductivity is derived from inversion of the airborne electromagnetic data and used to extrapolate buried valley morphology over the entire survey area. A spatially variable assignment
of the electrical conductivity at the bedrock surface is applied to different features of the buried valley morphology identified in the seismic cross-sections. Electrical conductivity is then used to guide construction of buried valley shapes
between seismic sections. The 3D locus of points defining each morphological valley feature is constructed using a path optimization routine that utilizes deviation from the assigned electrical conductivities as the cost function. Our resulting map
represents a bedrock surface of unprecedented detail with more complexity than has been suggested by previous investigations. Our procedure is largely data-driven with an adaptable degree of expert user input that provides a clear protocol for
incorporating different types of geophysical data into the bedrock mapping procedure. |
| Summary | (Plain Language Summary, not published)
In glaciated terrain, buried valleys often host aquifers that are significant groundwater resources. However, given the multitude of scales and spatial
complexity, buried valleys often remain undetected or insufficiently mapped. Accurate and thorough mapping of bedrock topography is a crucial step in detecting and delineating buried valleys and understanding process formation. We develop a bedrock
mapping procedure using ground-based and airborne geophysical data, and we present its application to the Spiritwood buried valley aquifer system in Manitoba, Canada. Our resulting bedrock map provides unprecedented detail with more complexity than
has been suggested by previous investigations. The bedrock surface is used as input to hydrogeological modelling of the Spiritwood buried valley aquifer system. |
| GEOSCAN ID | 297498 |
|
|