GEOLOGIC FRAMEWORK AND HYDROGEOLOGIC CHARACTERISTICS OF THE EDWARDS AQUIFER RECHARGE ZONE, BEXAR COUNTY, TEXAS
- Permanent Link:
- GEOLOGIC FRAMEWORK AND HYDROGEOLOGIC CHARACTERISTICS OF THE EDWARDS AQUIFER RECHARGE ZONE, BEXAR COUNTY, TEXAS
- Series Title:
- USGS Water-Resources Investigations
- G. Stein, William
B. Ozuna George
- Publication Date:
- Subjects / Keywords:
- Bexar County ( local )
Edwards Aquifer ( local )
Fault Zone ( local )
- serial ( sobekcm )
- In Bexar County, residential and commercial development on the Edwards aquifer recharge
zone is increasing. The aquifer possibly can be
contaminated by spills, leakage of hazardous
materials, or runoff from the rapidly developing
urban areas that surround, or are built on, the
intensely faulted and fractured, karstic limestone
outcrops characteristic of the recharge zone. Furthermore, some of the hydrogeologic subdivisions
that compose the Edwards aquifer have greater
effective porosity than others. The areas where the
most porous subdivisions crop out might provide
efficient avenues for contaminants to enter the
The Edwards aquifer recharge zone has relatively large permeability resulting, in part, from
the development or redistribution of secondary
porosity. Lithology, stratigraphy, diagenesis, and
karstification account for the effective porosity
and permeability in the Edwards aquifer outcrop.
Karst features that greatly enhance effective
porosity in the outcrop area include sinkholes and
Hydrogeologic subdivision VI, the Kirschberg evaporite member, appears to be the most
porous and permeable subdivision within the
Kainer Formation. Hydrogeologic subdivision HI,
the leached and collapsed members, undivided, is
the most porous and permeable subdivision within
the Person Formation. Hydrogeologic subdivision
II, the cyclic and marine members, undivided, is
moderately permeable, with both fabric- and notfabric-selective porosity.
The faults in northern Bexar County are part
of the Balcones fault zone. Although most of the
faults in this area trend northeast, a smaller set of
cross-faults trend northwest. Generally, the faults
are en echelon and normal, with the downthrown
blocks typically toward the coast.
- Original Version:
- USGS Water-Resources Investigations, Vol. 95-4030 (1995-01-01).
- Source Institution:
- University of South Florida Library
- Holding Location:
- University of South Florida
- Rights Management:
- This object is protected by copyright, and is made available here for research and educational purposes. Permission to reuse, publish, or reproduce the object beyond the bounds of Fair Use or other exemptions to copyright law must be obtained from the copyright holder.
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