The Permian and Cretaceous Aquifer Systems of Far West Texas Matthew M. Uliana, Ph.D., P.G. Geology...
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Transcript of The Permian and Cretaceous Aquifer Systems of Far West Texas Matthew M. Uliana, Ph.D., P.G. Geology...
The Permian and Cretaceous Aquifer Systems of Far
West Texas
Matthew M. Uliana, Ph.D., P.G.Matthew M. Uliana, Ph.D., P.G.Geology Program and Aquatic Resources (Dept. of Biology)Geology Program and Aquatic Resources (Dept. of Biology)
Talk Outline• Introduction
• Paleozoic depositional setting
• Aquifers in Paleozoic rocks– Marathon, Capitan, Rustler, Bone Springs
• Cretaceous depositional setting
• Aquifers in Cretaceous rocks– Edwards-Trinity (Plateau) aquifer
• Regional flow systems– Structural controls on groundwater flow
Aquifers of West Texas
Edwards-Trinity (Plateau)Edwards-Trinity (Plateau)
Bone Springs-Victorio PeakBone Springs-Victorio Peak
RustlerRustler
CapitanCapitan
MarathonMarathon
Paleozoic Depositional Settings• Permian
– Area was on the edge of a major super-continent called Pangea
– Basin surrounded by a large reef system
• Aquifers include– Marathon – Capitan– Rustler– Bone Springs-
Victorio Peak Aquifers
Marathon Aquifer
• Located in Brewster County north of Big Bend– Ordovician to Pennsylvanian
age (~500 – 300 million years ago)
– Located in the Marathon Uplift
• Water found in fractures and cavities in subsurface
• Not particularly productive
Capitan Aquifer• Occurs in the Capitan Reef
Complex– Ancient reef which formed around
the margins of the Delaware Basin in the Permian Period (~250 million years ago)
• algae, sponges, and tiny colonial animals called bryozoans
– Excellent exposure of the reef in Guadalupe Mountains National Park
• El Capitan
DelawareBasin
AB
Flow under Apache Mts.
• Flow through the Apache Mts. Area is not in the reef complex rocks– Flow is in the basin sediments– Probably controlled by fractures
Rustler Aquifer• Permian; also
associated with the Delaware Basin– Evaporites (gypsum
and anhydrite)– Formed when the basin
closed and dried up
Great Salt Lake
Rustler Water Quality• Well yields are generally low
– Controlled by fractures– Quite variable
• Usually high in sulfates– Rarely good enough for regular human
consumption
Bone Springs-Victorio Peak• Located in the Dell
City area• Limestone deposited
between the reef and the continent– Controlled by fractures
• Recharge comes from New Mexico – Primarily from the
Sacramento River
Cretaceous Depositional Settings• Much of North America was covered by shallow
tropical sea for millions of years• Lots of limestone deposited throughout Texas
– Most of the Cretaceous aquifers in Texas are in limestone
Edwards-Trinity Plateau• Cretaceous limestones• Only westernmost part is in the Trans-Pecos• Hydraulically-connected to the Cenozoic Pecos
Alluvial Aquifer
Regional Flow Systems
• Connections between different aquifers– Some can
cover dozens to hundreds of miles
– Controlled by several factors
Structural Controls • The tectonic events of the
past billion years created structural grains in the regional bedrock
• Creates patterns of fractures that control groundwater flow paths
• Examples include…– Permian carbonates in
Apache Mts.– Otero Mesa in New Mexico/
Hudspeth County
Conclusions• Paleozoic aquifers in far west Texas are
considered minor aquifers
• Aquifer properties…– Location, flow paths, permeability, water
quality
• … are generally controlled by the depositional setting and the regional structural trends