Ground-Water Hydraulics...in Eocene Aquifers of the East Texas Basin. Digital Download

RI0127D. Ground-Water Hydraulics and Hydrochemical Facies in Eocene Aquifers of the East Texas Basin, by G. E. Fogg and C. W. Kreitler. 75 p., 44 figs., 6 tables, 2 appendices, 1982. doi.org/10.23867/RI0127D. Downloadable PDF.

To purchase this publication in book format, please order RI0127.

ABSTRACT
Eocene stratigraphic units in the East Texas Basin are composed of a thick sedimentary sequence (approximately 2,000 ft [600 m]) of fresh-water aquifers and aquitards covering an area of approximately 15,000 mi² (51,000 km²). Analysis of abundant data on hydraulic head, pressure, and water chemistry from water wells tapping the Wilcox, Carrizo, and Queen City aquifers reveals the regional ground-water circulation patterns, locations and mechanisms of major recharge and discharge areas, and evolution of ground-water chemistry.

The Queen City aquifer is primarily a water-table (unconfined) system in which effects of topography create a series of local ground-water basins. The Wilcox-Carrizo aquifer system includes (1) an artesian (confined) section that is separated from the Queen City by the Reklaw Formation, a leaky aquitard, and (2) a water-table (unconfined) system where the Wilcox-Carrizo crops out along the west, north, and east margins of the basin. Structure and topography are major controls on ground-water circulation in the Wilcox-Carrizo. A structural ridge in the Wilcox-Carrizo corresponds roughly to a ground-water divide that separates a southward component of flow from one that is directed northeastward toward the Texas-Louisiana border. Topographically controlled vertical leakage between the Queen City and Wilcox-Carrizo aquifer systems affects circulation in the Wilcox-Carrizo. The vertical head differentials and the distribution of flowing wells indicate downward leakage over most of the basin and upward leakage only beneath the Trinity and Sabine Rivers. Similarly, pressure-versus-depth data from the Wilcox-Carrizo indicate a predominantly downward component of vertical flow that intensifies toward topographically higher areas and reverses direction beneath the Trinity River.

As ground water flows from outcrop down the hydraulic gradient into the artesian part of the Wilcox-Carrizo aquifer, it is consistently altered chemically from an acidic oxidized calcium-magnesium-bicarbonate sulfate water to a basic reduced sodium bicarbonate water. This change in the water chemistry is predominantly controlled by two reactions: calcite dissolution and cation exchange with montmorillonitic clays. Water samples with anomalous chemical composition (compared with regional chemistry) indicate salt dome dissolution or anomalous hydrologic conditions, such as relatively high rates of recharge to the artesian part of the Wilcox-Carrizo through leaky aquitards.

Keywords: aquifers, aquitards, Carrizo aquifer, East Texas Basin, Eocene, ground water, hydraulics, hydrochemistry, Queen City aquifer, Reklaw Formation, Sabine River, Trinity River, Wilcox aquifer, Texas



CONTENTS
ABSTRACT

INTRODUCTION

PREVIOUS WORK

SCOPE

HYDROGEOLOGIC SETTING

PHYSIOGRAPHY AND CLIMATE

SURFACE WATER

GEOLOGY RELATED TO GROUND WATER

Midway and Upper Cretaceous strata

Wilcox Group

Carrizo Formation

Reklaw Formation

Queen City Formation

Weches and Sparta Formations

Alluvium

Structural setting

GROUND-WATER PUMPAGE AND USE

AQUIFER PARAMETERS

AQUIFER HYDRAULICS

QUEEN CITY

WILCOX-CARRIZO

Potentiometric surface map

Impacts of topography

Impacts of geology and pumpage

Vertical leakage across the Reklaw aquitard

Vertical flow in the Wilcox-Carrizo system

Rate of ground-water flow

SUMMARY-AQUIFER HYDRAULICS.

WATER CHEMISTRY

PIPER DIAGRAMS OF QUEEN CITY-SPARTA AND WILCOX-CARRIZO WATER

DEVELOPMENT OF SODIUM BICARBONATE WATER

SULFATE REDUCTION AND REDUCING CONDITIONS

SILICA

CHLORIDE

SUMMARY-EVOLUTION OF WATER CHEMISTRY

EVOLUTION OF GROUND-WATER COMPOSITION AS A TRACER FOR GROUND-WATER FLOW

TOTAL DISSOLVED SOLIDS

Methods

Results

Discussion

IMPLICATIONS FOR TRANSPORT OF GROUND-WATER CONTAMINANTS

ACKNOWLEDGMENTS

REFERENCES

APPENDIX A: TRENDS IN GROUND-WATER USE, EAST TEXAS BASIN

APPENDIX B: BASIC AXIOMS OF PRESSURE-VERSUS-DEPTH INTERPRETATION

FIGURES

1. Location and structural features of the East Texas

2. Stratigraphic column and composite log of Tertiary formations, Smith County, East Texas Basin

3. Topographic map showing major reservoirs and locations of stream-flow gaging stations

4. Surface geology, East Texas Basin

5. Structural cross sections A-A', B-B', and C-C', showing Tertiary and Upper Cretaceous formations, East Texas Basin

6. Net-sand-thickness map, Wilcox Group

7. Percent-sand-thickness map, Wilcox Group

8. Mean net-clay-thickness map, Reklaw aquitard

9. Structure map, top of Wilcox Group

10. Mean transmissivity map, Sparta, Queen City, Carrizo, Wilcox, and Cypress aquifers

11. Plots of transmissivity and hydraulic conductivity versus sand-percent and net-sand values, Wilcox aquifer

12. Potentiometric levels, Queen City aquifer

13. Potentiometric surface, Wilcox-Carrizo aquifer system

14. Ground-water flow lines drawn from the Wilcox-Carrizo potentiometric surface

15. Topographically controlled leakage across an aquitard

16. Vertical head differentials measured between Queen City and Wilcox-Carrizo aquifers.

17. Profiles showing elevations of Wilcox-Carrizo water levels above major stream beds, Sabine River, Neches River, and Trinity River

18. Method of computing pressure head from conventional water-well data

19. Pressure-versus-depth plot of all data from the Wilcox-Carrizo system

20. Pressure versus depth for areas within 2 mi (3.2 km) of Trinity River, Neches River, and Sabine River

21. Mean slope of pressure-versus-depth regression lines versus land-surface elevation

22. Piper diagram of water chemistry, Queen City and Sparta aquifers

23. Piper diagram of water chemistry, Wilcox-Carrizo aquifer

24. Piper diagram of water chemistry from water wells screened shallower than 150 ft (46 m), Wilcox-Carrizo aquifer

25. Piper diagram of water chemistry from water wells screened deeper than 150 ft (46 m), Wilcox-Carrizo aquifer

26. Generation of Na⁺-HCO₃- ground water, Wilcox-Carrizo aquifer

27. Graph of Ca²⁺versus depth, Wilcox-Carrizo aquifer

28. Map view of Ca²⁺concentrations, Wilcox-Carrizo aquifer

29. Graph of pH versus total carbonate activity

30. Graph of pH versus depth, Wilcox-Carrizo aquifer

31. Map view of pH values, Wilcox-Carrizo aquifer

32. Graph of SO₄^2-activity versus depth, Wilcox-Carrizo aquifer

33. Map view of SO₄^2-concentrations. Wilcox-Carrizo aquifer.

34. Map view of SiO₂ concentrations, Wilcox-Carrizo aquifer

35. Graph of H₄SiO₂ versus depth

36. Graph of H₄SiO₄ activities versus saturation indices of amorphous Si02 and quartz

37. Graph of Cl^- activities versus depth, Wilcox-Carrizo aquifer

38. Map view of Cl^- concentrations, Wilcox-Carrizo aquifer

39. Graph of SO₄^2-activities versus depth, Carrizo aquifer

40. Graph of Cl^- activities versus depth, Carrizo aquifer

41. Graph of Cl^- concentrations versus depth, Gregg County, Texas

42. Map showing distribution of percent fresh water, Wilcox aquifer

43. Map showing distribution of fresh-water percentages having values less than 40 percent, the trends of high sand percent, and the Elkhart Graben-Mount Enterprise fault system

44. Induction-resistivity and spontaneous-potential curves for Wilcox aquifer near Oakwood Dome

TABLES

1. Flow characteristics of major rivers in the East Texas Basin

2. Water use in the East Texas Basin, 1974

3. Aquifer properties

4. Linear regression statistics for the Wilcox-Carrizo pressure-versus-depth data from confined and unconfined sections and 50-ft (15.2-m) intervals of land-surface elevation within each county

5. Linear regression statistics for the Wilcox-Carrizo pressure-versus-depth data from areas within 2 mi (3.7 km) of the major rivers

6. Water chemistry from wells in the Carrizo aquifer near flanks of Oakwood and Keechi salt domes


Citation
Fogg, G. E., and Kreitler, G. E., 1982, Ground-Water Hydraulics and Hydrochemical Facies in Eocene Aquifers of the East Texas Basin: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 127, 75 p.