Deformation mechanisms and hydraulic properties of fault zones in unconsolidated sediments; the Roer Valley Rift System, The Netherlands

In general, faults cutting through the unconsolidated sediments of the Roer Valley Rift System (RVRS), The Netherlands, form strong barriers to horizontal groundwater flow. The relationships between deformation mechanisms along fault zones and their impact on the hydrogeological structure of the fau...

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Bibliographic Details
Published in:Hydrogeology journal 2003-06, Vol.11 (3), p.319-332
Main Authors: Bense, V F, Van den Berg, EH, Van Balen, RT
Format: Article
Language:English
Subjects:
Conductivity
Damage
Deformation
Deformation mechanisms
Faults
Fluid dynamics
Fluid flow
Geology
Groundwater barriers
Groundwater flow
Hydraulic properties
Hydraulics
Hydrogeology
Plate tectonics
Sediments
Spatial distribution
Valleys
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Summary:In general, faults cutting through the unconsolidated sediments of the Roer Valley Rift System (RVRS), The Netherlands, form strong barriers to horizontal groundwater flow. The relationships between deformation mechanisms along fault zones and their impact on the hydrogeological structure of the fault zone are analyzed in a shallow (0-5 m below land surface) trench over one of the faults in the study area. Recently developed digital-image-analysis techniques are used to estimate the spatial distribution of hydraulic conductivity at the millimeter-scale and to describe the micromorphologic characteristics of the fault zone. In addition, laboratory measurements of hydraulic conductivity on core-plug samples show the larger-scale distribution of hydraulic conductivity in the damage zone flanking the main fault plane. Particulate flow is the deformation mechanism at shallow depths, which causes the damage zone around the fault, in the sand-rich parts, to have a relatively enhanced hydraulic conductivity. The fault core is characterized by reduced hydraulic conductivity due to clay smearing, grain-scale mixing, and iron-oxide precipitation.
ISSN:1431-2174
1435-0157
DOI:10.1007/s10040-003-0262-8