U.S. Department of the Interior

U.S. Geological Survey

In cooperation with the Oklahoma Water Resources Board

Geochemical Investigation of the Arbuckle-Simpson Aquifer, 

South-Central Oklahoma, 2004–06

Scientific Investigations Report 2009–5036
Cover: Photograph of the Vendome Well, Chickasaw National Recreation Area, Sulphur, Oklahoma.

Photograph by Scott Christenson, U.S. Geological Survey. 
Geochemical Investigation of the 

Arbuckle-Simpson Aquifer, South-Central 

Oklahoma, 2004–06

By Scott Christenson, Andrew G. Hunt, and David L. Parkhurst

In cooperation with the Oklahoma Water Resources Board

Scientific Investigations Report 2009–5036

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Christenson, Scott, Hunt, A.G., and Parkhurst, D.L., 2009, Geochemical investigation of the Arbuckle-Simpson aquifer, 

South-central Oklahoma, 2004–06: U.S. Geological Survey Scientific Investigations Report 2009–5036, 50 p. 
iii

Contents

Abstract ..........................................................................................................................................................1

Introduction ....................................................................................................................................................2

Purpose and Scope .............................................................................................................................4

Acknowledgments ...............................................................................................................................4

Description of the Study Area ....................................................................................................................4

Geology ..................................................................................................................................................4

Hydrology ..............................................................................................................................................7

Climate ..........................................................................................................................................7

Surface Water .............................................................................................................................7

Ground Water ............................................................................................................................10

Geochemical Investigation ........................................................................................................................14

Methods ...............................................................................................................................................14

Study Design ..............................................................................................................................14

Field-Sampling Protocols and Analytical Methods .............................................................16

Quality-Assurance Samples ...................................................................................................17

Ground-Water Quality .......................................................................................................................18

Descriptive Water Quality .......................................................................................................18

Percentiles ........................................................................................................................18

Comparison to Water-Quality Standards .....................................................................18

Water Type ........................................................................................................................22

Test Well ............................................................................................................................23

Geochemical Reactions ...................................................................................................................23

Saturation Indices ....................................................................................................................23

Carbonate Reactions ................................................................................................................24

Carbon-13 ...................................................................................................................................24

Vendome Well and Site 6 .........................................................................................................26

Ground-Water Dating ........................................................................................................................27

Helium-3/Tritium Dating ...........................................................................................................27

Chlorofluorocarbons ................................................................................................................28

Carbon-14 Dating ......................................................................................................................28

Dating Results ............................................................................................................................28

Dissolved Gas Modeling ..........................................................................................................31

Calculated Apparent Age (Mean Residence Time) .............................................................33

Tritium and Helium-3/Tritium Apparent Ages .......................................................................33

Chlorofluorocarbon Apparent Ages ......................................................................................34

Carbon-14 Apparent Ages .......................................................................................................35

Comparison of Helium-3/Tritium and Chlorofluorocarbon Dating Techniques ...............35

Terrigenic Helium ......................................................................................................................37

Summary .......................................................................................................................................................38

References Cited .........................................................................................................................................40

Appendix 1 ....................................................................................................................................................45
iv

Figures

1–8. Maps showing: 

1. Location of the Arbuckle-Simpson aquifer and study area, south-central 

Oklahoma .............................................................................................................................2

2. Geographic features of the Arbuckle-Simpson aquifer study area, southcentral Oklahoma ................................................................................................................3

3. Geologic map of the Arbuckle-Simpson aquifer study area, south-central 

Oklahoma .............................................................................................................................6

4. Perennial streams with drainage basins that include the Arbuckle-Simpson 

aquifer, south-central Oklahoma ......................................................................................8

5. Springs listed in the U.S. Geological Survey’s National Water Information System 

database within the Arbuckle-Simpson aquifer study area, southcentral Oklahoma ................................................................................................................9

6. Potentiometric surface in the Hunton Anticline, June 2005, south-central 

Oklahoma ...........................................................................................................................11

7. Locations of the Arbuckle-Simpson aquifer geochemical sampling sites, 

south-central Oklahoma ..................................................................................................12

8. Stiff diagrams of the Arbuckle-Simpson aquifer geochemical reconnaissance 

samples, south-central Oklahoma . ................................................................................13

9. Calcite and dolomite saturation indices and log partial pressure of carbon 

dioxide ................................................................................................................................25

10. Relation between neon-to-xenon ratio and argon concentration ...........................30

11. Historical measured tritium (3H) values in precipitation from R.L. Michel and 

the calculated 3H levels present ....................................................................................34

12. Comparison of reconstructed initial tritium (tritium [3H] plus tritiogenic 

helium-3 [3He*]) to historical tritium input levels .........................................................35

13. Comparison of helium-3/tritium (3He/3H) and chlorofluorocarbon (CFC) dating 

techniques .........................................................................................................................38

Tables

1. Monthly and annual average precipitation at Ada, Oklahoma (1971–2000) ......................7

2. Monthly and annual average temperature at Ada, Oklahoma (1971–2000) .......................7

3. Analytes and schedules for Arbuckle-Simpson geochemical sampling .........................15

4. Constituent concentrations and relative percent difference between an 

environmental sample (site number 29) and a replicate sample .......................................19

5. Summary statistics for physcial properties and chemical constituents from the 

Arbuckle-Simpson Hydrology Study geochemical reconnaissance samples ................20

6. Inverse models for Vendome well and site 6 ........................................................................26

7. Dissolved gas data ....................................................................................................................29

8. Dissolved gas modeling and helium-3/tritium (3He/3H) age determination ......................32

9. Chlorofluorocarbon data and age calculation ......................................................................36
v

Conversion Factors, Datums, and Abbreviations

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

acre-foot (acre-ft) 1,233 cubic meter (m3

)

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

gallon per minute (gal/min) 0.06309 liter per second (L/s)

Pressure

atmosphere, standard (atm) 101.3 kilopascal (kPa)

Transmissivity1

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d)

1

Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times foot of aquifer 

thickness ([(ft3/d)/ft2]/ft). In this report, the mathematically reduced form, foot squared per day (ft2/d), is used for 

convenience.

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Datums

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1988 (NAVD88).

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD27) or the North 

American Datum of 1983 (NAD83).

Altitude, as used in this report, refers to distance above the vertical datum.

Abbreviations

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) 

or micrograms per liter (μg/L).

Concentrations of chloroflurocarbons are given in picograms per kilogram (pg/kg), picomoles 

per kilogram (pmol/kg), or parts per trillion (ppt).

Concentrations of dissolved gasses are given in cubic centimeters per kilogram (cc/kg) or 

micro-cubic centimeters per kilogram (μcc/kg).

Concentrations of tritium are given in tritium units (TU).
vi

Permil: A unit expressing the ratio of stable-isotope abundances of an element in a sample to 

those of a standard material. Permil for stable isotopes are calculated as follows:

δ Sample

R R Sample

R =  −



 



1 000,  Standard

Standard

,

where R is the isotopic ratio of the least abundant isotope to the most abundant isotope. The 

following standards are used for reporting isotopes: Hydrogen-2/Hydrogen-1, VSMOW (Vienna 

Standard Mean Ocean Water); Oxygen-18/Oxygen-16, VSMOW; and Carbon-13/Carbon-12, 

VPDB (Vienna Pee Dee Belemnite) (Appelo and Postma, 2005). 
Abstract

A geochemical reconnaissance investigation of the 

Arbuckle-Simpson aquifer in south-central Oklahoma was 

initiated in 2004 to characterize the ground-water quality at 

an aquifer scale, to describe the chemical evolution of ground 

water as it flows from recharge areas to discharge in wells and 

springs, and to determine the residence time of ground water 

in the aquifer. Thirty-six water samples were collected from 

32 wells and springs distributed across the aquifer for chemical analysis of major ions, trace elements, isotopes of oxygen 

and hydrogen, dissolved gases, and age-dating tracers.

In general, the waters from wells and springs in the 

Arbuckle-Simpson aquifer are chemically suitable for all 

regulated uses, such as public supplies. Dissolved solids 

concentrations are low, with a median of 347 milligrams per 

liter (mg/L). Two domestic wells produced water with nitrate 

concentrations that exceeded the U.S. Environmental Protection Agency’s nitrate maximum contaminant level (MCL) of 

10 mg/L. Samples from two wells in the confined part of the 

aquifer exceeded the secondary maximum contaminant level 

(SMCL) for chloride of 250 mg/L and the SMCL of 500 mg/L 

for dissolved solids. Water samples from these two wells are 

not representative of water samples from the other wells and 

springs completed in the unconfined part of the aquifer. No 

other water samples from the Arbuckle-Simpson geochemical 

reconnaissance exceeded MCLs or SMCLs, although not every 

chemical constituent for which the U.S. Environmental Protection Agency has established a MCL or SMCL was analyzed as 

part of the Arbuckle-Simpson geochemical investigation.

The major ion chemistry of 34 of the 36 samples indicates the water is a calcium bicarbonate or calcium magnesium bicarbonate water type. Calcium bicarbonate water 

type is found in the western part of the aquifer, which is predominantly limestone. Calcium magnesium bicarbonate 

water is found in the eastern part of the aquifer, which is 

predominantly a dolomite. The major ion chemistry for these 

34 samples is consistent with a set of water-rock interactions. 

Rainfall infiltrates the soil zone, where the host rock, limestone or dolomite, dissolves as a result of uptake of carbon 

dioxide gas. Some continued dissolution of dolomite and 

precipitation of calcite occur as the water flows through the 

saturated zone. 

The major ion chemistry of the two samples from wells 

completed in the confined part of the aquifer indicates the 

water is a sodium chloride type. Geochemical inverse modeling determined that mixing of calcite-saturated recharge 

water with brine and dissolving calcite, dolomite, and gypsum 

accounts for the water composition of these two samples. 

One of the two samples, collected at Vendome Well in 

Chickasaw National Recreation Area, had a mixing fraction 

of brine of about 1 percent. The brine component of the 

sample at Vendome Well is likely to account for the relatively 

large concentrations of many of the trace elements (potassium, 

fluoride, bromide, iodide, ammonia, arsenic, boron, lithium, 

selenium, and strontium) measured in the water sample.

Carbon-14, helium-3/tritium, and chlorofluorocarbons 

were used to calculate ground-water ages, recharge temperatures, and mixtures of ground water in the ArbuckleSimpson aquifer. Thirty four of 36 water samples recharged 

the aquifer after 1950, indicating that water is moving quickly 

from recharge areas to discharge at streams and springs. Two 

exceptions to this classification were noted in samples 6 and 

15 (Vendome Well). Ground-water ages determined for these 

two samples by using carbon-14 are 34,000 years (site 6) and 

10,500 years (site 15). 

Concentrations of dissolved argon, neon, and xenon in 

water samples were used to determine the temperature of 

the water when it recharged the aquifer. The mean annual air 

temperature at Ada, Oklahoma, is 16 degrees Celsius (°C) 

and the median temperature of the 30 reconnaissance water 

samples was 18.1 °C. The average recharge temperature of 

most samples is 14.3 +/- 2.2 °C, which is below the mean 

annual air temperature (16 °C). Calculating a weighted annual 

recharge temperature based on mean monthly recharge rates 

from hydrograph separation techniques and mean monthly air 

temperature at Ada, Oklahoma, produces a value of 14.2 °C. 

The weighted annual recharge temperature corroborates the 

calculated noble gas recharge temperatures and indicates 

that recharge occurs during the cooler months of the year. 

Recharge temperatures of water samples from sites 6 and 15, 

the two flowing wells producing water from confined parts of 

the aquifer, are clearly too cold (8.2 and 6.6 °C, respectively) 

to be associated with present day temperatures. The colder 

recharge temperatures are consistent with the ground-water 

ages for these samples (34,000 years for site 6 and 10,500 

Geochemical Investigation of the Arbuckle-Simpson 

Aquifer, South-Central Oklahoma, 2004–06

By Scott Christenson, Andrew G. Hunt, and David L. Parkhurst
2 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

years for site 15), indicating recharge from an earlier, cooler 

time period, coupled with possible mass fractionation of the 

noble gases that decreases the overall recharge temperature. 

Introduction

The Arbuckle-Simpson aquifer is located in Carter, Coal, 

Johnston, Murray, and Pontotoc Counties in south-central 

Oklahoma (fig. 1). The aquifer was estimated to contain about 

9 million acre-feet of freshwater by Fairchild, Hanson, and 

Davis (1990). Freshwater from the aquifer supplies base flow 

to the Blue River, Byrds Mill Creek, Delaware Creek, Honey 

Creek, Mill Creek, Oil Creek, Pennington Creek, Rock Creek, 

Travertine Creek, and many small streams (fig. 2). Springs, 

including Byrds Mill Spring (the primary water supply for the 

City of Ada), and the springs in the Chickasaw National Recreation Area discharge from the aquifer. Wells completed in 

the aquifer supply water to cities (including Sulphur and Ada), 

industry, agriculture, and local residents.

In 2002, in search of future water supplies, the Central 

Oklahoma Water Resource Authority, consisting primarily of 

communities in Canadian County, Oklahoma, proposed to purchase water from the Arbuckle-Simpson aquifer, drill wells, 

and build an 88-mile pipeline from the Arbuckle-Simpson 

aquifer to Canadian County in central Oklahoma (Oklahoma 

Water Resources Board, 2003, p. 1). In Oklahoma, ground 

water is considered private property that belongs to the overlying surface owner. Thus, the planned withdrawal and transfer 

of water by the Central Oklahoma Water Resource Authority 

was considered by the State of Oklahoma to be a permissible use of ground water. However, local residents, citizens’ 

groups, and the National Park Service were concerned that 

large-scale withdrawals of water from the Arbuckle-Simpson 

aquifer would cause decreased flow in rivers and springs, 

which in turn could result in the loss of water supplies, recreational opportunities, and aquatic habitat. The withdrawals 

also could cause water levels in the aquifer to decrease, which 

could increase pumping costs and require replacement of 

public and domestic water-supply wells. Many protests were 

filed with the Oklahoma Water Resources Board regarding the 

planned water transfer. 

In response to these concerns, the Oklahoma Senate 

passed Senate Bill 288, which imposed a moratorium on the 

issuance of any temporary ground-water permits for municipal or public water supply outside of any county that overlies 

a “sensitive sole source groundwater basin;” the ArbuckleSimpson aquifer is the only aquifer in Oklahoma classified as 

sole source (Oklahoma Water Resources Board, 2003, p. 1). 

Senate Bill 288 states that the moratorium will remain in effect 

until the Oklahoma Water Resources Board completes a study 

of the Arbuckle-Simpson aquifer and determines a maximum 

annual yield. 

The Oklahoma Water Resources Board, in collaboration 

with the U.S. Bureau of Reclamation, the U.S. Geological 

Survey, Oklahoma State University, and the University of 

Oklahoma, initiated a comprehensive multi-year investigation 

of south-central Oklahoma’s Arbuckle-Simpson aquifer (Oklahoma Water Resources Board, 2003, p. 2). The study is known 

Figure 1. Location of the Arbuckle-Simpson aquifer and study area, south-central Oklahoma. 

100° 102° 98° 96°

36°

34°

OKLAHOMA

Area enlarged

0 50 100 MILES

0 50 100 KILOMETERS

LOCATION MAP

96°20' 96°30'

96°50' 96°40'

97°00'

97°20' 97°10'

34°40'

34°30'

34°20'

34°10'

GARVIN COUNTY

PONTOTOC COUNTY

COAL

COUNTYATOKA

JOHNSTON COUNTY

COUNTY

CARTER COUNTY

GARVIN

COUNTY

MARSHALL COUNTY

MURRAY COUNTY

0 5 10 20 MILES

0 10 5 15 20 KILOMETERS

15

U.S. Geological Survey digital data

Albers equal area conic projection

North American Datum of 1983

Standard Parallel: 29.5

Standard Parallel: 45.5 

Longitude of Central Meridian: -96

Latitude of Projection Origin: 23

Arbuckle-Simpson aquifer

Study area

Digital geologic data

 from Cederstrand (1996)

Scale 1:250,000
Introduction

3Figure 2. Geographic features of the Arbuckle-Simpson aquifer study area, south-central Oklahoma. 

96°20' 96°30'

96°40' 96°50'

97°00'

97°10' 97°20'

34°40'

34°30'

34°20'

34°10'

GARVIN COUNTY

PONTOTOC COUNTY

COAL COUNTY

ATOKA COUNTY JOHNSTON COUNTY CARTER COUNTY

GARVIN

COUNTY

MARSHALL COUNTY

MURRAY COUNTY

0 10 20 MILES 5

0 10 20 KILOMETERS 5 15

15

Digital geologic data from Cederstrand (1996)

Scale 1:250,000

U.S. Geological Survey digital dataAlbers equal area conic projectionNorth American Datum of 1983Standard Parallel: 29.5Standard Parallel: 45.5 Longitude of Central Meridian: -96Latitude of Projection Origin: 23

Arbuckle-Simpson aquiferBoundary of study area

EXPLANATION

Blue River

Washita

Creek

Delaware 

Mill

Clear Boggy Rock

Honey

Oil Creek

Byrds Mill

Travertine

Creek

Wildhorse

Creek

Creek

Creek

River

Creek

Creek

Creek

Pen

n

i

ngton

Creek

Washita

River

! !

!

!

Ada

Davis Sulphur

Connerville

Chickasaw National

Recreation Area

Arbuckle Anticline

Tishomingo

Anticline

Hunton Anticline

!

Byrds Mill Spring
4 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

as the “Arbuckle-Simpson Hydrology Study.” The objectives 

of the Arbuckle-Simpson Hydrology Study are as follows:

1. Characterize the Arbuckle-Simpson aquifer in terms of 

geologic setting, aquifer boundaries, hydraulic properties, 

water levels, ground-water flow, recharge, discharge, and 

water budget.

2. Characterize the area’s surface hydrology, including 

stream and spring discharge, runoff, base flow, and the 

relationship of surface water to ground water.

3. Construct a digital ground-water/surface-water flow 

model of the Arbuckle-Simpson aquifer system for use in 

evaluating the allocation of water rights and simulating 

management options.

4. Determine the chemical quality of the aquifer and principal streams, identify potential sources of natural contamination, and delineate areas of the aquifer that are most 

vulnerable to contamination.

5. Construct network stream models of the principal stream 

systems for use in the allocation of water rights.

6. Propose water management options, consistent with state 

water laws, that address water rights issues, the potential 

impacts of pumping on springs and stream base flows, 

water quality, and water supply development.

An investigation of the geochemistry of the ArbuckleSimpson aquifer, conducted by the U.S. Geological Survey in 

cooperation with the Oklahoma Water Resources Board, was 

initiated in partial fulfillment of objectives 1 and 4. 

Purpose and Scope

This report documents an investigation of the geochemistry of the Arbuckle-Simpson aquifer that was initiated in 2004 

to characterize the ground-water quality at an aquifer scale, 

describe the chemical evolution of ground water as it flows 

from recharge areas to discharge in wells and springs, and to 

determine the residence time of ground water in the aquifer. 

This report presents some information about the geology and 

hydrology of the aquifer but only as background information 

for the discussion of the geochemistry of the aquifer. The 

information in this report is partial fulfillment of objectives 1 

and 4 of the Arbuckle-Simpson Hydrology Study.

This report uses chemical analyses of spring and groundwater samples to describe the water quality and geochemistry 

of the aquifer. The description of the water quality consists 

of descriptive statistics of physical properties and chemical 

constituents in water samples, comparison to water-quality 

standards, and a map showing water type. The investigation 

of the geochemistry of the aquifer consisted of identification 

of geochemical processes affecting the major ion chemistry of 

the aquifer and use of tracers (such as carbon-14, tritium, chlorofluorocarbons, and dissolved gases) to determine groundwater ages and to identify ground-water flow processes. 

Acknowledgments

The authors are indebted to the many land owners, 

municipalities, and operators of rural water districts who 

provided access to the wells and springs sampled during this 

investigation. This report would not have been possible without their assistance and their permission to work on their land 

and facilities. 

The Arbuckle-Simpson Hydrology Study was conceived 

and directed by the Oklahoma Legislature and the staff and 

board members of the Oklahoma Water Resources Board. 

Many members of the Legislature, Board, and staff contributed 

to this study. In particular, Noel Osborn, staff geologist with 

the Oklahoma Water Resources Board, provided leadership 

and vision for the study, and participated in the data collection 

and analysis. 

The authors also wish to thank Dale Ferree, Shana 

Mashburn, and Jason Masoner of the U.S. Geological Survey 

Oklahoma Water Science Center for assistance in collecting 

water samples, and Dr. Ann Azadpour-Keeley with the U.S. 

Environmental Protection Agency’s Robert S. Kerr Environmental Research Laboratory, for providing bacteriological 

analyses of water samples. 

Description of the Study Area

The Arbuckle-Simpson aquifer crops out in south-central 

Oklahoma over an area of about 520 square miles (fig. 2). The 

aquifer underlies parts of Carter, Coal, Johnston, Murray, and 

Pontotoc Counties. Data outside the aquifer outcrop were considered to be useful in studying the aquifer, and thus a study 

area was defined at the beginning of the study on the basis of a 

set of townships in the public land survey system that extended 

beyond the perimeter of the aquifer. The study area includes 

56 townships (2,016 square miles). 

Geology

The Arbuckle-Simpson aquifer consists of the Timbered 

Hills, Arbuckle, and Simpson Groups, a group being a stratigraphic unit consisting of two or more formations deposited 

during a single geologic era. No confining layer separates 

the Timbered Hills Group from the Arbuckle Group and thus 

Timbered Hills Group is included in the Arbuckle-Simpson 

aquifer and is considered to be part of the same ground-water 

flow system. 

A detailed discussion of the geologic units that compose 

the Arbuckle-Simpson aquifer and adjacent formations is 

beyond the scope of this report. More comprehensive descriptions of the geology of the Arbuckle-Simpson aquifer and 

adjacent formations can be found in Ham (1955), Ham (1973), 

and Johnson (1991). 

The aquifer study area commonly is divided into three 

areas, which are designated as the Hunton, Tishomingo, and 
Description of the Study Area 5

Arbuckle Anticlines in this report (fig. 2). These designations 

are based loosely on geologic and topographic similarities, 

and the terms are not based strictly on geologic structures. The 

aquifer and bounding geohydrologic units are described herein 

in order from oldest to youngest. 

The Arbuckle-Simpson aquifer is underlain by Cambrian 

and Precambrian rhyolite and granite basement rocks. The 

basement rocks are as deep as about 8,000 feet in the few 

wells that penetrate the outcrop of the aquifer (Campbell and 

Weber, 2006). These basement rocks are at the land surface in 

the geologic structural center of the Arbuckle Anticline, as a 

few small inliers within the Tishomingo Anticline, and south 

of the Hunton Anticline where faulting has elevated them to 

the land surface (fig. 3). 

The Cambrian-age Timbered Hills Group ranges in 

thickness in the study area from 0 to about 700 feet (Fairchild, 

Hanson, and Davis, 1990) and consists of the Reagan Sandstone and Honey Creek Limestone. The Reagan Sandstone is 

composed primarily of quartz grains with some feldspar and 

glauconite (Ham, 1955). The Honey Creek Limestone is a 

limestone in the Arbuckle Anticline and a dolomite in other 

exposures within the study area. The Timbered Hills Group is 

at the land surface in only a small percentage of the outcrop of 

the Arbuckle-Simpson aquifer, about 8 square miles (fig. 3). 

The Timbered Hills Group is at the land surface in the geologic structural center of the Arbuckle Anticline, at the eastern 

edge of the Tishomingo Anticline, and at the southern edge of 

the Hunton Anticline. 

The Arbuckle Group, of Late Cambrian to Middle 

Ordovician age (fig. 3), consists of the Fort Sill Limestone, 

Royer Dolomite, Signal Mountain Formation, Butterly 

Dolomite, McKenzie Hill Formation, Cool Creek Formation, 

Kindblade Formation, and West Spring Creek Formation. 

Although the Arbuckle Group has been subdivided into geologic units based on a combination of lithostratigraphic and 

biostratigraphic parameters (Donovan, 1991), these geologic 

units are difficult to distinguish in the field and, as a consequence, the Arbuckle Group is treated as a single geologic unit 

in this report. The Arbuckle Group is thickest in the Arbuckle 

Anticline, as much as 6,700 feet (Ham, 1955), and thins to 

about 3,000 feet to the north and east in the Hunton Anticline 

(Campbell and Weber, 2006). The Arbuckle Group consists 

largely of carbonates with a few thin layers of sandstone and 

shale. Chert is abundant in some geologic units, and traces 

of evaporites can be found (Donovan, 1991). Limestone is 

the dominant carbonate in the Arbuckle Anticline, but to the 

north and east a transition to dolomite occurs in the Hunton 

Anticline (Ham, 1955). The Arbuckle Group is the dominant geologic unit at the land surface within the outcrop of 

the Arbuckle-Simpson aquifer with an outcrop area of about 

360 square miles. 

The Simpson Group of Ordovician age ranges in thickness in the study area from 0, where the Simpson Group has 

been removed by erosion, to 2,300 feet (Fairchild, Hanson, 

and Davis, 1990), and consists of the Joins Formation, Oil 

Creek Formation, McLish Formation, Tulip Creek Formation, 

and Bromide Formation. The Joins Formation is a thin-bedded 

limestone but the other formations consist of a basal sandstone, a middle shale, and an upper limestone (D.L. Hart, U.S. 

Geological Survey, written commun., 1972). The sandstones 

are 50 to 350 feet thick and consist of well-sorted, rounded, 

and frosted quartz grains that make excellent petroleum reservoirs outside of the outcrop of the Arbuckle-Simpson aquifer. 

Within the outcrop they are mined as high-purity sands for the 

manufacture of glass and other industrial uses (Ham, 1973). 

The Simpson Group covers an area of about 145 square miles 

of the land surface within the outcrop area of the ArbuckleSimpson aquifer and is at the land surface over a large area of 

the eastern part of the Hunton Anticline. Other areas where the 

Simpson Group is at the land surface include the southern and 

western boundaries of the Arbuckle and Tishomingo Anticlines, the northern boundaries of the Arbuckle and Hunton 

Anticlines, and southeast of Sulphur (fig. 3). 

The outcrop of the Arbuckle-Simpson aquifer represents 

a structural high, and outside of the outcrop of the aquifer 

the geologic units that comprise the aquifer are buried by 

younger rocks, except to the south where the basement rocks 

abut the aquifer. The upper surface of the geologic units in 

the Arbuckle-Simpson aquifer outside the outcrop area is an 

unconformity and many different geologic units overlie the 

aquifer, depending on location, including the Viola Group, 

Sylvan Shale, Hunton Group, Woodford Shale, and a variety 

of Mississippian geologic units (Donovan, 1991). Near the 

Chickasaw National Recreation Area (fig. 2), the ArbuckleSimpson aquifer is overlain by the Pennsylvanian-age Vanoss 

Group, which consists of a tightly cemented limestone 

conglomerate, a shale member, and minor sandstone lentils 

(Hanson and Cates, 1994). All geologic units younger than 

the Simpson Group are designated in this report as postSimpson geologic units, undifferentiated. In many locations 

the Arbuckle and Simpson Groups dip into the subsurface, 

such as near the Chickasaw National Recreation Area near 

Sulphur; in other locations faulting places the geologic units 

discontinuously in the subsurface, such as at the northeast 

boundary of the Hunton Anticline. 

The Arbuckle-Simpson aquifer is highly folded, faulted, 

and fractured. The rocks were subjected to intensive folding 

and faulting associated with major uplift of the area during 

early to late Pennsylvanian time. Features characteristic of 

Arbuckle Group deformation include an abundance of brittle 

fracturing (joints, shears, broken or collapsed folds), parallel 

folding, and pressure solution (Donovan, 1991). Major faults 

have offset stratigraphic units as much as 40 miles (Scheirer 

and Hosford Scheirer, 2006). Structural deformation increases 

to the southwest; rocks are more flat lying in the Hunton Anticline (dips less than 20 degrees), but tilting increases to the 

southwest with vertical and overturned beds to be found within 

the Arbuckle Anticline.

Small karst features can be seen over much of the outcrop 

area of the aquifer, but human-enterable air-filled caves are 

found only in a few locations. Lynch and Al-Shaieb (1991) 

document evidence of extensive paleokarst in Arbuckle Group 
6 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

Figure 3. Geologic map of the Arbuckle-Simpson aquifer study area, south-central Oklahoma. 

Geology modified from Cederstrand (1996)

Digital elevation model from

National Elevation Dataset (2001)

U.S. Geological Survey digital dataAlbers equal area conic projectionNorth American Datum of 1983Standard Parallel: 29.5Standard Parallel: 45.5 Longitude of Central Meridian: -96Latitude of Projection Origin: 23

0 10 20 MILES 50 10 20 KILOMETERS 5

15

15

Geologic age groupCretaceous formationPermian–Pennsylvanian formationsMississippian–Ordovician formationsOrdovician Simpson Group

EXPLANATION

Ordovician–Cambrian Arbuckle GroupCambrian Timbered Hills GroupCambrian–Precambrian igneous rocksWater

FaultBoundary of study areaArbuckle-Simpson aquifer boundary

Blue River

Washita

Creek

Delaware 

Mill

Clear Boggy

Rock

Honey

Oil Creek

Byrds Mill

Travertine

Creek

Wildhorse

Creek

Creek

Creek

River

Creek

Creek

Creek

Pennington

Creek

Washita

River

96°20' 96°30'

96°40' 96°50'

97°00'

97°10' 97°20'

34°40'

34°30'

34°20'

34°10'

Sulphur

!
Description of the Study Area 7

rocks in Oklahoma. A test well drilled as part of this investigation encountered voids with red-clay and calcite fillings, which 

are consistent with karst features at depth. 

Hydrology

The hydrology of the Arbuckle-Simpson aquifer has 

been described in numerous publications, including Fairchild, 

Hanson, and Davis (1990), Hanson and Cates (1994), Savoca 

and Bergman (1994), Andrews and Burrough (2002), and Harp 

and McLin (1986). The description of the hydrology of the 

Arbuckle-Simpson aquifer included in this report is information needed to understand the geochemistry and water quality 

of the aquifer, which are the subjects of this report. 

Climate

The study area is considered to have a moist, sub-humid 

climate (Fairchild, Hanson, and Davis, 1990). Mean annual 

precipitation, based on data from 1971 to 2000 at Ada, Oklahoma, is 41.26 inches (National Climatic Data Center, 2008). 

Monthly average precipitation for Ada is shown in table 1. 

Monthly average temperatures for Ada are shown in table 2. 

Annual potential evapotranspiration is about equal to annual 

precipitation. Koren and others (1998) calculated annual 

potential evaporation at Blue River near Blue, Oklahoma, 

about 30 miles southeast of the aquifer, to be 44.11 inches. 

Annual pan evaporation averaged 49.38 inches at Atoka, about 

20 miles east of the aquifer, and 55.78 inches at Chickasha, 

about 30 miles northwest of the aquifer (Farnsworth and 

Thompson, 1982). Fairchild, Hanson, and Davis (1990) estimated actual evapotranspiration for the study area to be about 

31 inches per year, or about 80 percent of precipitation (based 

on data from 1969–71 and 1976–79).

Surface Water

Perennial streams that originate in the Arbuckle-Simpson 

aquifer include Blue River, Byrds Mill Creek, Delaware 

Creek, Honey Creek, Mill Creek, Pennington Creek, Oil 

Creek, Rock Creek, and Travertine Creek (fig. 4). Blue 

River, which drains a large part of the Hunton Anticline, is 

the largest stream that originates within the study area. The 

drainage basin for Rock Creek near Sulphur is partially on the 

Arbuckle-Simpson aquifer. The Washita River flows across 

the aquifer and a small part of its drainage basin is on the 

outcrop of the Arbuckle-Simpson aquifer. The Washita River 

may receive some ground-water discharge from the aquifer, 

but the discharge of the Washita River is large and the river 

is in contact with the aquifer for only a short distance. No 

measurements were made as part of this study that might show 

if ground water originating in the Arbuckle-Simpson aquifer is 

discharging to the river.

Many springs discharge from the Arbuckle-Simpson 

aquifer. The U.S. Geological Survey’s National Water Information System database lists 140 springs in the study area 

(fig. 5). Many of the springs are located near the boundary 

Table 1. Monthly and annual average 

precipitation at Ada, Oklahoma (1971–2000). 

[Data from National Climatic Data Center (2006)]

Month Average precipitation

(inches)

January 1.85

February 2.19

March 3.68

April 3.75

May 5.53

June 4.53

July 2.70

August 3.02

September 4.57

October 3.90

November 3.14

December 2.40

Annual 41.26

Table 2. Monthly and annual average temperature at Ada, 

Oklahoma (1971–2000). 

[Data from National Climatic Data Center (2006)]

Temperature 

(degrees Celsius)

Daily

maximum

Daily

minimum Mean

January 9.9 -2.4 3.8

February 13.4 0.2 6.8

March 18.3 4.7 11.5

April 23.0 9.1 16.1

May 26.8 14.3 20.6

June 30.8 18.9 24.8

July 33.8 21.5 27.7

August 33.6 20.8 27.2

September 29.4 16.5 22.9

October 23.9 10.4 17.2

November 16.6 4.1 10.4

December 11.4 -0.8 5.3

Annual 22.1 9.8 16.2
8 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

Figure 4. Perennial streams with drainage basins that include the Arbuckle-Simpson aquifer, south-central Oklahoma.

0 10 20 MILES 5

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15

Digital geologic data from Cederstrand (1996)

Scale 1:250,000

U.S. Geological Survey digital dataAlbers equal area conic projectionNorth American Datum of 1983Standard Parallel: 29.5Standard Parallel: 45.5 Longitude of Central Meridian: -96Latitude of Projection Origin: 23

Blue River

Washita

Creek

Delaware 

Mill

Clear Boggy

Rock

Honey

Oil Creek

Byrds Mill

Travertine

Creek

Wildhorse

Creek

Creek

Creek

River

Creek

Creek

Creek

Pennington

Creek

Washita

River

#

Geologic unitSimpson GroupArbuckle GroupTimbered Hills GroupIgneous rocksBoundary of study areaU.S. Geological Survey gaging station and number

EXPLANATION

07329852

!

!

!

Ada

Davis Sulphur GARVIN COUNTY

PONTOTOC COUNTY

COAL COUNTY

ATOKA COUNTY JOHNSTON COUNTY CARTER COUNTY

GARVIN

COUNTY

MARSHALL COUNTY

MURRAY COUNTY

Chickasaw National

Recreation Area

#

#

#

#

#

#

#

#

#

#

07334200

07329852

07329780

07332390

07331300

07331295

07331200

07329700

07331000

07329849

96°20' 96°30'

96°40' 96°50'

97°00'

97°10' 97°20'

34°40'

34°30'34°20'

34°10'
Description of the Study Area 9Figure 5. Springs listed in the U.S. Geological Survey’s National Water Information System database within the Arbuckle-Simpson aquifer study area, south-central Oklahoma.

!

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0 10 20 MILES 5

0 10 20 KILOMETERS 5 15

15

Digital geologic data from Cederstrand (1996)

Scale 1:250,000

U.S. Geological Survey digital dataAlbers equal area conic projectionNorth American Datum of 1983Standard Parallel: 29.5Standard Parallel: 45.5 Longitude of Central Meridian: -96Latitude of Projection Origin: 23

Blue River

Washita

Creek

Delaware 

Mill

Clear Boggy

Rock

Honey

Oil Creek

Byrds Mill

Travertine

Creek

Wildhorse

Creek

Creek

Creek

River

Creek

Creek

Creek

Creek

Pennington

Washita

River

Geologic unitSimpson GroupArbuckle GroupTimbered Hills GroupIgneous rocksBoundary of study areaSpring

EXPLANATION

!

Ada

Davis Sulphur

! Connerville

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GARVIN COUNTY

PONTOTOC COUNTY

COAL COUNTY

ATOKA COUNTY JOHNSTON COUNTY CARTER COUNTY

GARVIN

COUNTY

MARSHALL COUNTY

MURRAY COUNTY

Chickasaw National

Recreation Area

96°20' 96°30'

96°40' 96°50'

97°00'

97°10' 97°20'

34°40'

34°30'34°20'

34°10'

Byrds Mill Spring
10 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

of the aquifer outcrop. A large group of springs is located 

on Blue River west of Connerville, and these springs are not 

located near the outer boundary of the aquifer. Another group 

of springs is found in the Chickasaw National Recreation Area 

near Sulphur outside of the outcrop of the aquifer. Freshwater 

and mineralized springs are found within and near the Chickasaw National Recreation Area. The origin of the water flowing 

to the springs in the Chickasaw National Recreation Area is 

discussed in more detail in this report. Byrds Mill Spring, 

with an average annual discharge (based on a period of record 

from 1990 to 2005) of 18.6 cubic feet per second, is the largest 

spring in Oklahoma and serves as the primary water supply for 

the City of Ada. During most years, discharge from springs 

maintains flow in the larger streams in the study area in the 

absence of rainfall. 

Fairchild, Hanson, and Davis (1990) estimated that 

during the time of their investigation (1976-79) evapotranspiration accounted for 80 percent of the annual precipitation. 

They estimated that the remaining 20 percent of precipitation 

discharges from the study area as surface water and includes 

4.7 inches per year base flow and 2.9 inches per year direct 

runoff. 

Ground Water

The primary source of water in the aquifer is diffuse 

recharge from precipitation, estimated by Fairchild, Hanson, 

and Davis (1990) to be about 4.7 inches per year in the Hunton 

Anticline in the late 1970s. Ground-water flow in the Hunton 

Anticline generally is to the southeast. The potentiometric 

surface calculated from head measurements obtained at wells, 

springs, and streams is shown in figure 6. Ground water discharges to streams and springs, with the largest discharges in 

the downgradient part of the aquifer. Limited potentiometric 

data in the Arbuckle and Tishomingo Anticlines show generally radial flow patterns (Fairchild, Hanson, and Davis, 1990). 

As in the Hunton Anticline, ground water in the Arbuckle 

and Tishomingo Anticlines discharges to streams and springs. 

The depth of fresh ground water within the outcrop area is not 

known but a small number of wells exceed 1,000 feet in depth 

and do not encounter saline water. A test well completed as 

part of this investigation was drilled to a depth of 1,820 feet 

and produced freshwater. 

The freshwater zone of the aquifer generally coincides 

with the outcrop area of the aquifer. Freshwater extends 

beyond the outcrop in several locations; the most notable is 

located near the town of Sulphur and the Chickasaw National 

Recreation Area. Ground water flows west from the Hunton 

Anticline and becomes confined beneath Pennsylvanian-age 

cemented conglomerates. Ground water discharges to springs, 

Travertine and Rock Creeks, and wells, some of which are 

flowing (artesian) wells. A few wells produce freshwater from 

the Arbuckle-Simpson aquifer just west of Rock Creek, west 

of Sulphur, indicating freshwater circulates at least that far to 

the west. Springs in the Chickasaw National Recreation Area 

become increasingly saline from east to west, indicating the 

presence of a freshwater-saline water transition zone. The zone 

where freshwater circulation is inferred west of the outcrop of 

the Hunton Anticline is shown in figure 6 as “Post-Simpson 

group.” The extent of the freshwater zone is inferred from 

the locations of wells that produce water from the ArbuckleSimpson aquifer beneath the post-Simpson group, but the 

precise extent of the freshwater zone is not known. The 

geohydrology of the area surrounding Chickasaw National 

Recreation Area has been described in numerous publications, 

including Andrews and Burrough (2002), Hanson and Cates 

(1994), and Harp and McLin (1986). 

Another location where relatively freshwater extends 

beyond the aquifer outcrop is at approximately 34°44 ́ north 

96°43 ́ west (North American Datum of 1927 [NAD27]). 

An old drilling report on file at the U.S. Geological Survey 

Oklahoma Water Science Center indicates that at that location a 1,967-foot deep industrial well, which was plugged 

back to 1,865 feet, produced water in 1954 in which total 

dissolved solids ranged from 672 to 2,226 parts per million. 

Although the geologic unit in which the well is completed is 

not specified in the data on file for this well, the description 

of the cuttings from the drilling log makes it likely the well is 

completed in the Arbuckle or Simpson Groups. 

One well within the aquifer outcrop in the eastern part of 

the Hunton Anticline is known to produce water with higher 

dissolved solids than typical of water within the outcrop (typical water chemistry is discussed in the “Descriptive Water 

Quality” section of this report). The well, site 6 in figures 7 

and 8 and appendix 1, is 1,400 feet deep. On October 21, 

2004, the specific conductance of water from this well was 

1,350 microsiemens per centimeter (μS/cm) and the dissolved 

solids were 768 milligrams per liter (mg/L), which is the 

most saline water that was sampled within the aquifer outcrop 

as part of this investigation. No other deep water wells are 

known in this part of the aquifer, but this single well indicates 

that salinity probably increases with depth within the aquifer 

outcrop area. 

Beyond the outcrop area of the aquifer, the Arbuckle and 

Simpson Groups are major producers of oil and gas. Oil and 

gas fields are located near the boundary of the aquifer. Boyd 

(2002) shows oil and gas fields in contact with the aquifer at 

the northern extent of the Arbuckle Anticline at approximately 

34°30 ́ north latitude, 97°10 ́ west longitude (North American Datum of 1983 [NAD83]) and at the northern extent of 

the Hunton Anticline at approximately 34°38 ́ north latitude, 

96°40 ́ west longitude (NAD83). Wells in the Chickasaw 

National Recreation area, known as the East (approximately 

34°30 ́ north latitude, 96°56 ́ west longitude, NAD27) and 

West (approximately 34°30 ́ north latitude, 96°57 ́ west longitude, NAD27) Observation Wells, produce small amounts 

of asphalt (Hanson and Cates, 1994). In an area about 3 miles 

south of Sulphur, sandstone within the Oil Creek Formation 

contains about 8 percent asphalt and was mined for roadsurfacing material from 1890 until 1962 (Ham, 1973). 

Ground water in the Arbuckle-Simpson aquifer moves 

through porous media, solution-enlarged conduits, and 
Description of the Study Area 11

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0 10 20 MILES 5

0 10 20 KILOMETERS 5 15

15

Digital geologic data from Cederstrand (1996)

Scale 1:250,000

U.S. Geological Survey digital dataAlbers equal area conic projectionNorth American Datum of 1983Standard Parallel: 29.5Standard Parallel: 45.5 Longitude of Central Meridian: -96Latitude of Projection Origin: 23

Blue River

Washita

Creek

Delaware 

Mill

Clear Boggy

Rock

Honey

Oil Creek

Byrds Mill

Travertine

Creek

Wildhorse

Creek

Creek

Creek

River

Creek

Creek

Creek

Creek

Pennington

Washita

River

Geologic unitPost-Simpson group, undifferentiated—Areashaded is inferred to have a freshwater flowsystem in the Arbuckle-Simpson aquiferoverlain by undifferentiated geologic unitsyounger than the Simpson GroupSimpson GroupArbuckle GroupTimbered Hills GroupIgneous rocks

EXPLANATION

1000

!

Boundary of study areaPotentiometric contour—Interval 20 feetData point—Elevation of the potentiometricsurface determined from the elevations ofsprings, streams, and water levels in wells

!

!

!

!

!

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980

960

1080

1060

1040

1000

1020

1120

940

1140

920

900 880

860

1160

840

800

1180

1040

1160

1060

1060

980

1040

1100

1160

960

1100

1180

760

720

1180

1180

1140

1080

1000

1020 1020

1120

1100

960

1120

1040

1000

940

1160

1140

1080

1140

880

920

960

1000

820

1120

1100

Ada

Davis Sulphur GARVIN COUNTY

PONTOTOC COUNTY

COAL COUNTY

ATOKA COUNTY JOHNSTON COUNTY CARTER COUNTY

GARVIN

COUNTY

MARSHALL COUNTY

MURRAY COUNTY

Chickasaw National

Recreation Area

96°20' 96°30'

96°40' 96°50'

97°00'

97°10' 97°20'

34°40'

34°30'34°20'

34°10'

Figure 6. Potentiometric surface in the Hunton Anticline, June 2005, south-central Oklahoma.
12 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

Figure 7. Locations of the Arbuckle-Simpson aquifer geochemical sampling sites, south-central Oklahoma.

!

!

!

0 10 20 MILES 5

0 10 20 KILOMETERS 5 15

15

Digital geologic data from Cederstrand (1996)

Scale 1:250,000

U.S. Geological Survey digital dataAlbers equal area conic projectionNorth American Datum of 1983Standard Parallel: 29.5Standard Parallel: 45.5 Longitude of Central Meridian: -96Latitude of Projection Origin: 23

Blue River

Washita

Creek

Delaware 

Mill

Clear Boggy

Rock

Honey

Oil Creek

Byrds Mill

Travertine

Creek

Wildhorse

Creek

Creek

Creek

River

Creek

Creek

Creek

Pennington

Creek

Washita

River

Geologic unitSimpson GroupArbuckle GroupTimbered Hills GroupIgneous rocksBoundary of study areaSampling site and identifier—See appendix 1Spring and numberWell and number

EXPLANATION

9

!17

!

! !

!

!

!

!9

4

30

20 19

14

!

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!

!

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!

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!

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!

8 7

6

5

3

2

1

32

31

29

28

27

26

25

24

23

22

21

17

18 16

15

13

12

10

11 Arbuckle Anticline Tishomingo

Anticline

Hunton Anticline

Ada

Davis Sulphur GARVIN COUNTY

PONTOTOC COUNTY

COAL COUNTY

ATOKA COUNTY JOHNSTON COUNTY CARTER COUNTY

GARVIN

COUNTY

MARSHALL COUNTY

MURRAY COUNTY

Chickasaw National

Recreation Area

96°20' 96°30'

96°40' 96°50'

97°00'

97°10' 97°20'

34°40'

34°30'34°20'

34°10'

Oil well

Test hole
Description of the Study Area 13Figure 8. Stiff diagrams of the Arbuckle-Simpson aquifer geochemical reconnaissance samples, south-central Oklahoma.

Digital geologic data from Cederstrand (1996)

Scale 1:250,000

U.S. Geological Survey digital dataAlbers equal area conic projectionNorth American Datum of 1983Standard Parallel: 29.5Standard Parallel: 45.5 Longitude of Central Meridian: -96Latitude of Projection Origin: 23

Stiff diagrams

Stiff diagrams, a graphical method to portray water quality, illustrate the relative abundance of major mineral ions in water samples. The shapes of the diagrams indicate dominant cations and anions characterizing the water and the width of the diagram is an approximation of the total ionic content. 

Sodium + Potassium

Calcium

Magnesium

Chloride

Bicarbonate

Sulfate

Blue River

Washita

Creek

Delaware 

Mill

Clear Boggy

Rock

Honey

Oil Creek

Byrds Mill

Travertine

Creek

Wildhorse

Creek

Creek

Creek

River

Creek

Creek

Creek

Pennington

Creek

Washita

River

Chickasaw National

Recreation Area

Geologic unitSimpson GroupArbuckle GroupTimbered Hills GroupIgneous rocksBoundary of study areaSampling site and identifier—See appendix 1Spring and numberWell and number

EXPLANATION

!

9

17

!

GARVIN COUNTY

PONTOTOC COUNTY

COAL COUNTY

ATOKA COUNTY JOHNSTON COUNTY CARTER COUNTY

GARVIN

COUNTY

MARSHALL COUNTY

MURRAY COUNTY

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8

7

6

5

3

2

1

29

28

27

26

25

24

23

22

21

17

18 16

15

13

12

11

10

9

30

4

20 19

14

! !

!

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0 10 20 MILES 5

0 10 20 KILOMETERS 5 15

15

96°20' 96°30'

96°40' 96°50'

97°00'

97°10' 97°20'

34°40'

34°30'

34°20'

34°10'
14 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

fractures. The sandstone units within the Simpson Group, 

where they are exposed at the land surface, appear to be 

porous media that would allow substantial ground-water 

flow. Several human-enterable caves in the study area contain 

streams, and the presence of paleokarst at depth in the aquifer 

makes it likely that some fraction of the ground-water flow 

in the aquifer is moving in conduits. Electrical resistivity 

imaging as part of the current study documented the presence of epikarst developed at some locations in the aquifer (T. 

Halihan, Oklahoma State University, written commun., 2004), 

which may enhance ground-water flow. 

The Arbuckle-Simpson aquifer contains many fractures 

that are likely pathways for ground-water movement. Many 

voids were encountered in a test well drilled during this investigation, and some of these voids produced large quantities of 

water (total production from this test well was estimated to 

be 1,000 gallons per minute). Subsequent testing of the test 

well by using packers to isolate intervals revealed that not all 

fractures produce substantial quantities of water. 

Both the Arbuckle and Simpson Groups yield substantial quantities of water to wells and thus are considered to be 

aquifers. However, a number of observations indicate that, at 

least in the eastern part of the Hunton Anticline, the Simpson 

Group is acting as a confining layer. These indications are 

(1) the presence of at least one flowing well, (2) a group of 

springs on Blue River that occurs at a location immediately 

before the Blue River flows across the Simpson Group (fig. 5), 

and (3) the hydraulic gradients on the potentiometric map in 

Fairchild, Hanson, and Davis (1990, plate 2) that are considerably steeper in the Simpson Group than in the adjacent 

Arbuckle Group. The Simpson Group includes sequences 

of sandstones, shales, and limestones that appear to conduct 

water horizontally, thus yielding water to wells, but are less 

conductive vertically.

Fairchild, Hanson, and Davis (1990) determined the 

hydraulic properties of the Arbuckle-Simpson aquifer by using 

a combination of aquifer tests and regional techniques that use 

streamflow and water-level hydrographs. They estimated the 

average transmissivity of the aquifer to be 15,000 feet squared 

per day and the storage coefficient to be 0.008 (unitless).

Geochemical Investigation

A geochemical reconnaissance investigation of the 

Arbuckle-Simpson aquifer was initiated in 2004 to characterize the ground-water quality at an aquifer scale, describe the 

chemical evolution of ground water as it flows from recharge 

areas to discharge in wells and springs, and determine the 

residence time of ground water in the aquifer. Characterization 

of aquifer-scale ground-water quality was accomplished by 

(1) collecting 36 water samples from 32 wells and springs distributed across the aquifer for chemical analysis of major ions, 

trace elements, isotopes of oxygen and hydrogen, dissolved 

gases, and age-dating tracers; and (2) calculating descriptive 

statistics by using the results of the chemical analyses of the 

water samples. The chemical analyses also were used as input 

to geochemical models to evaluate the chemical evolution of 

the water as it moves through the aquifer. Age-dating tracers 

were used to determine the approximate time of recharge and 

residence time of ground water in the aquifer.

Methods

The study design of the Arbuckle-Simpson Hydrology 

Study relied on collecting ground-water and spring samples 

for analysis for a wide variety of analytes. The selection of 

sampling sites and the purpose of different kinds of samples 

are described in the “Study Design” section. The actual 

sampling process and analytical methods are described in the 

“Field-Sampling Protocols and Analytical Methods” section. 

Finally, efforts to assess sample contamination and reproducibility are described in the “Quality-Assurance Samples” 

section.

Study Design

The sampling of Arbuckle-Simpson aquifer wells and 

springs consisted of two parts, geochemical reconnaissance sampling and targeted sampling. The purpose of the 

geochemical reconnaissance sampling was to collect water 

samples (1) that could be used to describe the shallow groundwater quality of the Arbuckle-Simpson aquifer, (2) for input 

to geochemical models to evaluate the chemical evolution 

of the water as it moves through the aquifer, (3) to analyze 

for age-dating tracers to determine the approximate time of 

recharge and residence time of ground water in the aquifer, 

and (4) to guide additional sampling efforts. A small number 

of additional targeted samples were collected after the initial 

reconnaissance to take advantage of sampling opportunities or 

to investigate specific research topics. 

For the geochemical reconnaissance, ground- and springwater samples were collected from 24 wells and 5 springs 

during October and November 2004. The wells and springs 

included in the reconnaissance were selected to obtain broad 

coverage of the study area, including the Arbuckle, Tishomingo, and Hunton Anticlines. Shallow wells were selected 

(less than 500 feet deep) because most deep wells in this 

aquifer are completed with long open intervals and produce water from many zones. The suite of analytes for most 

samples included major ions, trace elements, nutrients, oxygen 

and hydrogen isotopes, chlorofluorocarbons (CFCs), dissolved 

gases, and tritium (table 3). Six wells and springs that were 

suspected to intercept long ground-water flow paths were 

sampled for analysis of carbon-14 and carbon-13/carbon-12 

ratio. 

After the initial sampling of 24 wells and 5 springs, 

Byrds Mill Spring was sampled because it drains most of 

the northeastern part of the Hunton Anticline and is the 

major source of water for the City of Ada. The City of Ada 

granted permission to sample the spring and samples were 
Geochemical Investigation 15

collected in November 2005. The chemical analysis of the 

water sample from Byrds Mill Spring is included in the 

regional-scale analysis of water-chemistry data in this report. 

Thus, a total of 24 wells and 6 springs are included in the 

Arbuckle-Simpson geochemical reconnaissance. The results of 

the chemical analyses for these 30 sites are included in appendix 1 and are labeled as sites 1 through 30.

After completion of the geochemical reconnaissance, 

additional samples, referred to as “targeted samples,” were 

collected from wells to address two specific issues. One of 

the specific issues was an interest in the chemistry and flow 

system for the mineralized springs of the Chickasaw National 

Recreation Area. Water discharging from the springs was 

hypothesized to be a mixture of freshwater from the ArbuckleSimpson aquifer and brines that surround the aquifer. A 

sample of brine was collected from an oil well (site 31 

in figure 7 and appendix 1) that is about 3 miles west of 

Chickasaw National Recreation Area and produces fluids from 

the Oil Creek Formation of the Simpson Group. The same 

suite of chemical constituents was analyzed for the oil well 

sample as the 30 reconnaissance samples, including carbon-14 

and carbon-13/carbon-12 ratio, although samples for noble 

gases and tritium were not collected. The chemical analysis of 

the water sample from the oil well (sample 31 in appendix 1) 

Table 3. Analytes and schedules for Arbuckle-Simpson geochemical sampling.

[USGS, U.S. Geological Survey; *, not collected for all samples]

Major ions (USGS schedule 934) Nutrients (USGS schedule 101)

Boron Nitrogen, ammonia

Bromide Nitrogen, nitrite

Calcium Nitrogen, nitrite + nitrate

Chloride Phosphorous, orthophosphate

Fluoride

Iodide Oxygen/hydrogen isotopes (USGS schedule 1142)

Magnesium Deuterium/protium ratio

Potassium Oxygen-18/oxygen-16 ratio

Residue (total dissolved solids)

Silica Chlorofluorocarbons*

Sodium Chlorofluorocarbon-11

Sulfate Chlorofluorocarbon-12

Chlorofluorocarbon-113

Trace elements (USGS schedule 1673)

Aluminum Carbon-14 suite*

Antimony Carbon-14

Arsenic Carbon-13/carbon-12

Barium

Beryllium Tritium/dissolved gases

Cadmium Argon

Chromium Helium

Cobalt Krypton

Copper Methane

Iron Nitrogen/argon ratio

Lead Oxygen

Lithium Xenon

Manganese Argon-40/argon-36 ratio

Molybdenum Neon-20/neon-22 ratio

Nickel Nitrogen/argon ratio

Selenium Tritium by helium-3 ingrowth

Silver

Strontium

Thallium

Uranium, natural

Vanadium

Zinc 
16 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

is not included in regional-scale analysis of water-chemistry 

data of the Arbuckle-Simpson aquifer because the water 

from this well is not part of the freshwater flow system in the 

Arbuckle-Simpson aquifer. For example, the data from this 

sample were not used in calculating percentiles in the 

“Descriptive Water Quality” section of this report. 

Another specific issue about the geochemistry of the 

Arbuckle-Simpson aquifer was the depth to which freshwater 

circulates within the aquifer. The few wells drilled in the study 

area for maximum production, such as the wells belonging to 

the cities of Ada and Sulphur, produced sufficient water by 

drilling to about 1,000 feet. Because there are no producing 

oil or gas wells within the outcrop of the aquifer, no information about the depth of freshwater is available from oil and 

gas wells. Limited water-chemistry data from a single well 

near the center of the Hunton Anticline (approximate location 

34°31 ́ north, 96°46 ́ west, NAD27) is documented in 

Fairchild, Hanson, and Davis (1990). These data show freshwater at a depth of 2,500 feet, although there is little information about the methods employed to collect the sample, which 

may represent a composite sample from a long open borehole, 

including shallow freshwater zones. 

Two test wells were drilled as part of the current study 

to collect high-quality water samples at depth from the 

Arbuckle-Simpson aquifer. The initial goal of the drilling was 

to drill to the granitic basement rocks or until saline water was 

encountered. The plan was to drill with compressed air and an 

air-hammer bit until the air could no longer remove cuttings 

from the test well, then switch to air or hydraulic rotary methods. Large voids that produced large quantities of water were 

encountered during drilling, which caused the air hammer not 

to function correctly. The first test well was abandoned at a 

depth of 628 feet because of excess water, and a second test 

well was started about 160 feet from the first well with larger 

diameter air-hammer bits. Large volumes of water once again 

caused problems with the air-hammer drilling that necessitated 

a switch from the relatively rapid air-hammer process to a 

much slower air-rotary process. The available funding for the 

drilling effort was expended before the target was reached, and 

drilling ceased at a depth of 1,820 feet. The rock in the test 

well was competent, and the borehole was left uncased below 

a 35-foot length surface casing.

Water samples were collected during drilling from the 

second, deeper test well (site 32 in figure 7 and appendix 1). 

The selection of the sampled intervals was made on the basis 

of drilling conditions (such as reports of fractures by the 

driller), drill cuttings, and the amount of water produced. Five 

water samples were collected by removing the drill pipe and 

bit and inserting a single packer on the drill pipe to isolate the 

lowermost zone of the drill hole. However, drilling foam was 

used during drilling, and even after purging the well overnight the produced water still contained drilling foam, which 

indicated that the samples were contaminated with air from the 

drilling process. Thus, the samples were not analyzed for the 

planned comprehensive suite of analytes. Specific conductance 

in water from the shallowest zone (an open borehole drilled 

to 120 feet) was 595 μS/cm. Specific conductance from the 

deepest zone (a single packer set at 1,282 feet, so the sampled 

zone was 1,282 to 1,820 feet) was identical, 595 μS/cm. Major 

cations and anions were analyzed at Oklahoma State University (T. Halihan, Oklahoma State University, written commun., 

2006) for samples collected at the time of drilling. Remarkably little variation in water chemistry was found between the 

deepest and shallowest samples. 

The test well was left undisturbed for 9 months after the 

initial drilling process to dissipate the air and foam introduced 

by the drilling process, and then the test well was sampled by 

using a combination of single and double (straddle) packers. 

Five distinct zones were sampled at different depths to create a 

geochemical profile. Unfortunately the test well partially collapsed during the 9-month period, and a blockage was encountered at a depth of 1,604 feet. The deepest zone was sampled 

with a single packer set on a smooth section of borehole at a 

depth of 1,492 feet and the drill hole was pumped from below 

that depth. The same analytes were collected for the five zones 

as for the reconnaissance samples except no samples were collected for carbon-14 or the carbon-13/carbon-12 ratio. 

None of the chemical analyses of the water samples from 

the test well are included in the regional-scale water-chemistry 

data of the Arbuckle-Simpson aquifer, because the analyses 

would tend to bias the regional-scale data toward a single 

point and because the samples were collected from an entirely 

different type of well with different downhole equipment from 

all other well samples. The results of the chemical analyses for 

the test hole are included in appendix 1 and are listed as site 

32, samples 32 through 36.

Field-Sampling Protocols and Analytical 

Methods

All water samples were collected by using standardized 

U.S. Geological Survey protocols (Wilde and others, 1998). 

Most sampled wells were domestic wells in daily use and 

equipped with submersible pumps. The protocol for sampling 

the well was to connect the sampling manifold to a fitting as 

close as possible to the well head by using a garden-hose connector. The sampling manifold consisted of a plastic gardenhose connector attached to clear Tygon tubing, which was 

connected to several splitters and valves to control flow. 

One flow line discharged to waste, one flow line was connected to a flow-through cell, and one flow line was used 

for sampling. For springs and flowing wells (which were not 

equipped with pumps), an additional sampling line was used. 

This additional sampling line consisted of a short length of 

pre-cleaned stainless steel tubing that was connected to a small 

length of Tygon tubing, which in turn was connected to the 

inlet of the sampling manifold. A peristaltic pump was used to 

pump water from the spring or flowing well into the sampling 

manifold. 

Prior to sampling, field measurements of specific conductance, pH, temperature, and dissolved oxygen were made 

with a calibrated multiprobe in a sealed flow-through cell. The 
Geochemical Investigation 17

wells were pumped to remove at least three casing volumes 

of water prior to any field measurements. Specific conductance, pH, temperature, and dissolved oxygen were measured 

at 5-minute intervals until the chemistry of the discharge 

water stabilized. The stability criteria used were (1) less than 

10-percent variation in specific conductance; (2) less than 

0.1-unit variation in pH; (3) less than 0.5-degree Celsius variation in temperature; and (4) less than 0.3-mg/L variation in 

dissolved oxygen. After the stability criteria were met, water 

was diverted to an enclosed sampling chamber to prevent contamination during sampling.

Major ion, trace element, nutrient, carbon-14, and 

carbon-13/carbon-12 ratio samples were filtered by using a 

0.45-micrometer pore-size disposable capsule filter. The 

filtered samples for dissolved cations and trace elements 

were acidified to a pH less than 2 with trace-element-grade 

nitric acid. Samples for CFCs were not filtered; samples were 

collected in borosilicate glass bottles and sealed with metal 

foil seals while submerged in a metal, water-filled bucket. 

Nutrient samples were filtered with a 0.45-micrometer 

pore-size disposable capsule filter, collected in opaque 

brown polyethylene bottles, chilled to 4 degrees Celsius, 

and sent by overnight courier to arrive at the U.S. Geological Survey’s National Water Quality Laboratory within 

48 hours of sample collection. Samples for tritium were 

collected in polyethylene bottles and sealed with polycone 

caps. Samples for dissolved gases were collected in copper tubes pinched with refrigeration clamps. Samples for 

carbon-14 and carbon-13/carbon-12 ratio were filtered through 

a 0.45-micrometer pore-size disposable capsule filter and 

collected in a glass bottle underwater. Samples for tritium and 

oxygen and hydrogen isotopes were not filtered; samples were 

collected in glass bottles and sealed with polycone caps. 

Decontamination was done by pumping and circulating a 

0.1-percent solution of laboratory soap through the tubing and 

manifold for 10 minutes. About 3 gallons of deionized water 

were then pumped through the sampling manifold and tubing 

to rinse any residual soap or mineralized water; the sampling 

manifold and tubing were then stored in clean plastic bags 

(Wilde and others, 1998).

Alkalinity was measured in the field immediately after 

sampling by using an incremental titration with 0.16-normal 

standardized sulfuric acid past the bicarbonate-carbonic acid 

inflection point (about pH 4.5). The titration was done in 

duplicate or until agreement within 2 percent was achieved. 

Several laboratories and schedules of analytes were used 

(table 3) for the geochemical assessment of the ArbuckleSimpson aquifer. All major ion, trace element, and nutrient 

samples were sent to the U.S. Geological Survey’s National 

Water Quality Laboratory (Fishman, 1993). Oxygen/hydrogen 

isotope samples were sent to the U.S. Geological Survey’s 

Reston Stable Isotope Laboratory in Reston, Virginia (Coplen, 

Wildman, and Chen, 1991; Epstein and Mayeda, 1953). CFC 

samples were sent to the U.S. Geological Survey’s Chlorofluorocarbon Laboratory in Reston, Virginia (Busenberg and 

others, 2006). The Environmental Isotope Laboratory at the 

University of Waterloo in Ontario, Canada analyzed carbon-14 

(Stuiver and Polach, 1977) and carbon-13/carbon-12 ratio 

(McCrea, 1950). Tritium and dissolved gas samples were 

sent to the U.S. Geological Survey’s Noble Gas Laboratory in 

Denver, Colorado. 

Quality-Assurance Samples

Quality-assurance samples were collected and analyzed 

to quantify the accuracy, precision, and potential bias of environmental samples. Quality-assurance samples for this study 

consisted of blanks and a replicate sample.

Blank samples are used to indicate if equipment or field 

conditions could bias the environmental samples. Two kinds 

of blank samples were collected during the geochemical 

investigation, a field blank and an equipment blank. The 

field blank sample was obtained by pumping high-purity 

pesticide- and inorganic-grade blank water through the sampling equipment at a field site and was processed in a manner 

identical to an environmental sample. The field blank was 

used to determine if the sampling equipment, decontamination, or the field environment could bias the environmental 

sample. The equipment-blank sample was collected at the 

end of the reconnaisance sampling, also by pumping highpurity pesticide- and inorganic-grade blank water through the 

sampling equipment used for environmental samples in the 

laboratory of the U.S. Geological Survey Oklahoma Water 

Science Center, eliminating the potential for field contamination. The equipment-blank sample was used to determine if 

the sampling equipment or decontamination process biased 

the samples. The field and equipment blanks were analyzed 

by using the major ion and trace element schedules; the field 

blank also was analyzed for the nutrient schedule.

The blank samples indicated that contaminants were 

not introduced in any substantial quantity by the sampling 

equipment or field conditions. Most constituents were not 

detected above the laboratory minimum reporting levels, with 

the following exceptions. Aluminum [26 micrograms per liter 

(μg/L)], silica (1.76 mg/L), and sodium (0.44 mg/L) were 

detected in the equipment blank. Chloride (0.11 mg/L), iodide 

(0.001 mg/L), and vanadium (0.1 μg/L) were detected in the 

field blank. The aluminum concentration in the equipment 

blank was 26 μg/L, higher than the aluminum concentration 

in any environmental sample. Thus, the aluminum data for all 

environmental samples are suspect. The silica, sodium, and 

chloride concentrations in the blank samples were less than 

the lowest concentration in any environmental sample, and 

the small concentrations of these constituents in the blank 

samples are not considered to be at a concentration that would 

require action. Most environmental samples had no detectable 

iodide or iodide concentrations near the minimum reporting 

level, thus the presence of iodide in the field blank means the 

samples with low concentrations of detectable iodide may 

have been contaminated. A small number of environmental 

samples had no detectable vanadium or vanadium concentrations close to the laboratory minimum reporting level, and thus 
18 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

the presence of vanadium in the field blank means that a small 

number of samples with low concentrations of vanadium may 

have been contaminated. 

A replicate sample was collected and analyzed at one 

of the environmental sample sites. The sample was collected 

sequentially after an environmental sample, without the use 

of a splitting device, and thus could have been sampling water 

with a different chemistry than the environmental sample if the 

chemistry of the sampled well was changing during sampling. 

The relative percent difference (RPD) between the concentrations from the two samples was calculated as follows: 





 



 +

− =

2

100

21

21

CC

CC

RPD , (1)

where 

RPD is the relative percent difference, 

C1 is the constituent concentration in the environmental 

sample, and 

C2 is the concentration in the replicate sample. 

The results of the calculations of the relative percent difference are shown in table 4.

In general, analyzed concentrations in the replicate 

sample closely matched concentrations in the environmental sample. Only 6 of 43 constituents exceeded a RPD of 5 

percent. For the 6 constituents that exceeded a 5 percent RPD, 

all were low concentrations close to the laboratory minimum 

reporting level. For example, the highest RPD was 66.7 percent for fluoride, but the environmental and replicate sample 

fluoride concentrations were 0.2 and 0.1 mg/L. Thus, although 

the relative percent difference is large for these constituents, 

the difference in concentrations is small. The small RPDs

calculated for the replicate sample show that the results for the 

geochemical reconnaissance are reproducible. 

Ground-Water Quality

Descriptive Water Quality

A general description of the water quality of the 

Arbuckle-Simpson aquifer was prepared by (1) comparing 

the results of the chemical analyses of water samples to waterquality standards, (2) calculating percentiles for concentrations of some of the chemical constituents analyzed in water 

samples, and (3) determining the chemical water type of the 

samples. 

Percentiles

Percentiles for each analyte were calculated for the 30 

reconnaissance samples. A percentile is a value on the scale 

of 100 that indicates the percent of a distribution that is equal 

to or below it. For example, if the 10th percentile of a set of 

100 numbers has the value 27, then 10 percent of the numbers 

(10 numbers) are less than or equal to 27; the median of the 

set is the 50th percentile. Percentiles are a convenient method 

to show the distribution of a chemical constituent within a 

dataset. The percentiles calculated for the Arbuckle-Simpson 

reconnaissance data are shown in table 5.

Some of the analytical results for the Arbuckle-Simpson 

water-quality data were censored; that is, the concentration of 

a chemical constituent was less than the minimum concentration that the laboratory was able to quantify. Some constituents 

were censored at different concentrations, in which case, all 

data were censored at the largest censored concentration for 

calculating percentiles. 

Concentrations of analytes were relatively uniform for 

most constituents in water samples from wells and springs 

sampled during the Arbuckle-Simpson reconnaissance. For 

example, the inter-quartile range (data ranging from the 25th 

to the 75th percentiles) of dissolved solids ranged only from 

331 to 384 mg/L for the reconnaissance samples. Many waterquality constituents listed in table 5 have small inter-quartile 

ranges, indicating relatively uniform water composition. Constituents were considered to have small inter-quartile range 

if the 25th percentile was greater than or equal to one-half of 

the 75th percentile or both the 25th and 75th percentiles were 

censored. Constituents with small inter-quartile ranges include 

specific conductance, alkalinity, dissolved solids, calcium, 

magnesium, bicarbonate, carbonate, fluoride, bromide, iodide, 

silica, nitrite, ammonia, orthophosphate, aluminum, antimony, 

barium, beryllium, boron, cadmium, chromium, cobalt, iron, 

molybdenum, silver, and thallium. 

The maximum concentration for many constituents came 

from samples from a single site, site 15, which is a flowing 

well known as Vendome Well and is part of the Chickasaw 

National Recreation Area. Vendome Well is probably the bestknown well in the Arbuckle-Simpson aquifer. The highest concentrations for specific conductance, dissolved solids, sodium, 

potassium, chloride, fluoride, bromide, iodide, ammonia, 

arsenic, boron, lithium, selenium, and strontium are from the 

samples collected from Vendome Well. However, Vendome 

Well is in the confined part of the aquifer and appears to be at 

the very edge of the freshwater ground-water flow system and 

is not representative of water produced from the unconfined 

part of the aquifer. If Vendome Well had not been sampled as 

part of the Arbuckle-Simpson geochemical reconnaissance, 

most of the maximum values in constituent concentrations 

shown in table 5 would be considerably smaller. 

Comparison to Water-Quality Standards

The chemical analyses from the Arbuckle-Simpson 

reconnaissance samples were compared to the water-quality 

standards established by the U.S. Environmental Protection 

Agency (USEPA) for public water systems. The USEPA 

establishes a Maximum Contaminant Level (MCL) for some 

chemical constituents and a Secondary Maximum Contaminant Level (SMCL) for other constituents (USEPA, 2006). 
Geochemical Investigation 19

Table 4. Constituent concentrations and relative percent difference between an environmental sample (site number 29) and a 

replicate sample. 

[mg/L, milligrams per liter; CaCO3, calcium carbonate; N, nitrogen; <, less than; =, one or both concentrations censored, so relative percent difference cannot 

be calculated, although results are equivalent; P, phosphorus; E, detected analytes with concentrations between long-term method detection level and laboratory 

reporting level are reported as estimated by the U.S. Geological Survey’s National Water Quality Laboratory because a detection in this region should have a 

<1-percent probability of being a false positive (Childress and others, 1999); μg/L, micrograms per liter] 

Constituent Environmental sample Replicate sample Relative percent difference

Alkalinity (mg/L as CaCO3

) 546 550 0.7

Dissolved solids (mg/L) 628 632 .6

Calcium (mg/L) 118 118 0

Magnesium (mg/L) 77.5 77.3 .3

Sodium (mg/L) 7.97 8.01 .5

Potassium (mg/L) 2.47 2.44 1.2

Bicarbonate (mg/L) 666 670 .6

Carbonate (mg/L) 0 0 0

Sulfate (mg/L) 50.6 50.5 .2

Chloride (mg/L) 10.8 10.8 0

Fluoride (mg/L) .2 .1 66.7

Bromide (mg/L) .28 .19 38.3

Iodide (mg/L) .007 .007 0

Silica (mg/L) 13.2 13.2 0

Nitrite (mg/L as N) <.008 <.008 =

Nitrite plus nitrate (mg/L as N) 2.95 3.15 6.6

Ammonia (mg/L as N) <.04 <.04 =

Orthophosphate (mg/L as P) <.4 E.01 =

Aluminum (μg/L) <2 <2 =

Antimony (μg/L) <.2 <.2 =

Arsenic (μg/L) E.2 E.2 0

Barium (μg/L) 119 124 4.1

Beryllium (μg/L) <.06 <.06 =

Boron (μg/L) 19 19 0

Cadmium (μg/L) E.03 E.03 0

Chromium (μg/L) <.8 E.7 =

Cobalt (μg/L) .345 .362 4.8

Copper (μg/L) 22.2 22.6 1.8

Iron (μg/L) 19 19 0

Lead (μg/L) .19 .19 0

Lithium (μg/L) .8 .9 11.8

Manganese (μg/L) 3.3 3.4 3.0

Molybdenum (μg/L) <.4 <.4 =

Nickel (μg/L) 2.08 2.31 10.5

Selenium (μg/L) E.4 .7 54.6

Silver (μg/L) <.2 <.2 =

Strontium (μg/L) 86.4 86.5 .1

Thallium (μg/L) <.04 <.04 =

Vanadium (μg/L) .8 .8 0

Zinc (μg/L) 12.0 12.1 .8

Deuterium/protium ratio (permil) -33.6 -32.9 2.1

Oxygen-18/oxygen-16 ratio (permil) 5.73 5.72 .2

Uranium (μg/L) .80 .82 2.5
20 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06 Table 5. Summary statistics for physical properties and chemical constituents from the Arbuckle-Simpson Hydrology Study geochemical reconnaissance samples. [μS/cm, microsiemens per centimeter; °C, degree Celsius; mg/L milligrams per liter; CaCO3, calcium carbonate; <, less than; N, nitrogen; P, phosphorus; μg/L, micrograms per liter; †, constituent detected in blank samples at concentrations similar to environmental samples thus constituent concentrations in environmental samples are suspect] Properties and constituents Sample size Minimum Percentiles Maximum 5 10 25 50 75 90 95 Properties and major ions Specific conductance (μS/cm) 30 377 492 517 597 634 719 860 1,350 2,100 pH (standard units) 30 6.7 6.7 6.7 6.8 6.9 7.0 7.1 7.2 7.2 Temperature (°C) 30 16.1 16.7 17.4 18.0 18.4 18.9 19.5 19.8 20.6 Oxygen, dissolved (mg/L) 29 .1 .5 .7 3.3 4.9 6.7 7.6 7.7 8.2 Alkalinity (mg/L as CaCO3

) 30 179 256 258 297 325 338 358 443 546

Dissolved solids (mg/L) 30 222 291 301 331 347 384 494 768 1,250Calcium (mg/L) 30 63.2 67.6 70.4 76.7 80.8 104 121 133 134Magnesium (mg/L) 30 3.13 4.97 6.96 23.0 34.5 38.9 47.6 55.1 77.5Sodium (mg/L) 30 1.18 1.50 1.61 2.15 3.82 8.33 13.2 141 316Potassium (mg/L) 30 .37 .38 .46 .79 1.10 2.11 9.52 11.4 12.8Bicarbonate (mg/L) 30 218 313 314 362 397 412 436 540 666

Carbonate (mg/L) 30 0 0 0 0 0 0 0 0 0

Sulfate (mg/L) 30 4.9 5.5 5.5 7.5 10.8 17.1 35.3 49.2 50.6

Chloride (mg/L) 30 1.22 1.42 1.60 2.28 3.35 9.82 17.2 279 558

Fluoride (mg/L) 30 .1 .1 .1 .1 .1 .2 .2 .7 .7

Bromide (mg/L) 28 <.20 <.20 <.20 <.20 <.20 <.20 .28 .96 2.08

Iodide (mg/L) 30 <.004 <.004 <.004 <.004 <.004 <.004 .005 .034 .062

Silica (mg/L) 30 7.86 8.82 9.01 9.51 10.4 12.4 13.2 13.3 14.0

Nutrients

Nitrite (mg/L as N) 30 <.008 <.008 <.008 <.008 <.008 <.008 <.008 <.008 <.008Nitrite plus nitrate (mg/L as N) 30 <.06 <.06 <.06 .42 1.05 2.61 5.47 14.4 14.4

Ammonia (mg/L as N) 30 <.04 <.04 <.04 <.04 <.04 <.04 <.04 <.04 .43

Orthophosphate (mg/L as P) 30 <.04 <.04 <.04 <.04 <.04 <.04 <.04 <.04 <.04

Trace elements

Aluminum (μg/L)† 29 <2 <2 <2 <2 <2 <2 <2 <2 6

Antimony (μg/L) 30 <.20 <.20 <.20 <.20 <.20 <.20 <.20 <.20 <.20Arsenic (μg/L) 30 <.2 <.2 <.2 <.2 <.2 .2 .4 .5 .5
Geochemical Investigation

21

Table 5. Summary statistics for physical properties and chemical constituents from the Arbuckle-Simpson Hydrology Study geochemical reconnaissance samples—Continued.

Properties and constituents Sample size Minimum Percentiles Maximum 5 10 25 50 75 90 95

Trace elements—Continued

Barium (μg/L) 30 35 36 38 47 60 88 171 213 240

Beryllium (μg/L) 30 <.06 <.06 <.06 <.06 <.06 <.06 <.06 <.06 <.06Boron (μg/L) 30 11 11 11 13 17 21 26 321 496

Cadmium (μg/L) 30 <.04 <.04 <.04 <.04 <.04 <.04 <.04 .04 .88

Chromium (μg/L) 30 <.8 <.8 <.8 <.8 <.8 <.8 <.8 <.8 2.4

Cobalt (μg/L) 30 <.040 .152 .160 .189 .247 .305 .345 .373 .389

Copper (μg/L) 30 <.4 <.4 .4 .9 1.6 3.8 5.9 9.5 22.2

Iron (μg/L) 30 <18 <18 <18 <18 <18 <18 <18 18 19

Lead (μg/L) 30 <.08 <.08 <.08 <.08 .13 .28 .50 .91 .93

Lithium (μg/L) 30 <.6 <.6 <.6 .9 1.1 2.2 4.7 37.9 66.2

Manganese (μg/L) 30 <.2 <.2 <.2 <.2 <.2 1.1 1.5 3.3 7.3

Molybdenum (μg/L) 30 <.4 <.4 <.4 <.4 <.4 <.4 1.2 2.9 4.0

Nickel (μg/L) 30 <.06 .45 .45 .58 .77 1.57 1.85 2.08 2.26

Selenium (μg/L) 30 <.4 <.4 <.4 <.4 <.4 .5 .9 1.7 2.5

Silver (μg/L) 29 <.2 <.2 <.2 <.2 <.2 <.2 <.2 <.2 <.2Strontium (μg/L) 30 22.6 42.3 42.7 67.2 83.2 163 441 2,480 6,860Thallium (μg/L) 30 <.04 <.04 <.04 <.04 <.04 <.04 <.04 .04 .09

Vanadium (μg/L) 30 <.3 <.3 <.3 .4 .6 1.0 1.1 1.3 2.8

Zinc (μg/L) 30 <.6 <.6 <.6 1.1 3.4 10.5 13.2 30.9 196

Isotopes and radionuclides

Deuterium/protium ratio (permil) 30 -35.6 -35.2 -33.6 -31.2 -29.9 -28.7 -27.7 -25.5 -24.0

Oxygen-18/oxygen-16 ratio (permil) 30 -6.39 -5.83 -5.73 -5.40 -5.24 -5.05 -4.89 -4.56 -4.23

Uranium (μg/L) 30 <.04 <.04 .13 .25 .35 .67 .86 1.00 1.67
22 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

The MCLs are established to protect public health by limiting the levels of contaminants in drinking water (USEPA, 

2006). The SMCLs are non-enforceable guidelines regulating 

contaminants that may cause cosmetic effects (such as skin or 

tooth discoloration) or aesthetic effects (such as taste, odor, 

or color) in drinking water. The USEPA recommends secondary standards to water systems but does not require systems to 

comply (USEPA, 2006).

Most wells and springs sampled for the ArbuckleSimpson geochemical reconnaissance were not public water 

systems, and the water-quality standards do not apply to 

these wells and springs. However, the USEPA water-quality 

standards were used to provide a basis for comparison to 

established water-quality standards. Not every chemical 

constituent for which the USEPA has established an MCL 

or SMCL was analyzed as part of the Arbuckle-Simpson 

geochemical reconnaissance. 

In general, the waters from wells and springs in the 

Arbuckle-Simpson aquifer are chemically suitable for all 

regulated uses, such as public supplies. Dissolved solids 

concentrations are low, with a median of 347 and an interquartile range of 331 to 384 mg/L. Two domestic wells 

(sites 2 and 17) produced water with nitrate concentrations 

of 14.4 mg/L (coincidentally both wells produced water 

with identical nitrate concentrations) that exceeded the 

nitrate MCL of 10 mg/L. Nitrate is the most widespread 

contaminant of ground water (Hallberg and Keeney, 1993). 

Unique conditions not associated with the Arbuckle-Simpson 

aquifer are required for nitrate to be naturally elevated in 

ground water; therefore, most elevated nitrate is associated 

with anthropogenic activity such as agriculture or waste 

disposal. Potential sources of nitrate associated with the 

Arbuckle-Simpson aquifer are livestock and domestic septic 

systems. Many of the sampled wells are shallow domestic 

or stock wells located near these potential sources of nitrate. 

Nitrate concentrations are generally well below the MCL in 

most of the samples, which is a positive outcome from this 

investigation. No other maximum contaminant levels were 

exceeded. 

Samples from two wells, sites 6 and 15, that represent 

the confined part of the aquifer, exceeded the SMCL for 

chloride of 250 mg/L. Samples from site 6 had a chloride 

concentration of 279 mg/L, and the sample from site 15 

had a chloride concentration of 558 mg/L. Both sites are 

flowing wells from confined parts of the aquifer. One well 

(site 6) is a stock well that is not used for human consumption, 

but the other site, Vendome Well (site 15), is a flowing well 

in Chickasaw National Recreation Area from which visitors 

frequently drink. Samples from these two wells also exceeded 

the SMCL of 500 mg/L for dissolved solids. Samples from 

site 6 had a dissolved solids concentration of 768 mg/L, and 

the sample from site 15 had a dissolved solids concentration 

of 1,250 mg/L. Water samples from these two wells in the 

confined part of the aquifer are not representative of water 

samples from the other wells and springs completed in the 

unconfined part of the aquifer, and both wells consistently are 

exceptional when considering most aspects of the geochemistry of the Arbuckle-Simpson aquifer. No other water samples 

from the Arbuckle-Simpson geochemical reconnaissance 

exceeded SMCLs.

Water Type

The major ion chemistry of 34 of the 36 water samples 

was a calcium bicarbonate or calcium magnesium bicarbonate water type. Stiff diagrams, which graphically represent 

the dominant major cations and anions dissolved in the 

water, are shown in figure 8. Each Stiff diagram in figure 8 

is located at the site of the well or spring from which the 

water sample was collected. The geometric pattern of the 

Stiff diagram and the relative size indicate the general water 

type and relative concentration of total dissolved solids. 

Some wells or springs, such as site 1, produce water in which 

calcium is the dominant cation (the middle left axis of the 

Stiff diagram) and bicarbonate (the middle right axis of the 

Stiff diagram) is the dominant anion. Stiff diagrams of water 

samples from wells and springs producing water from the 

Arbuckle Anticline (the western part of the aquifer) show a 

distinct diamond-shape pattern of calcium bicarbonate type 

waters. Stiff diagrams of water samples from wells and springs 

producing water from the Hunton Anticline (the eastern part of 

the aquifer) have a slightly different shape in which the lower 

left axis, representing magnesium, is longer (see for example 

the Stiff diagram for site number 28). Water from the Hunton 

Anticline tends to have higher magnesium concentration, 

which is consistent with the geology. The predominant rock 

type in the Arbuckle Anticline is limestone, which consists 

mostly of the mineral calcite, CaCO3

. The predominant rock 

type in the Hunton Anticline is dolomite, which consists 

mostly of the mineral dolomite, CaMg(CO3)

2

 (the term 

“dolomite” refers to a rock type and a mineral). The water 

types for sites on the Tishomingo Anticline include both the 

calcium bicarbonate water type and the calcium magnesium 

bicarbonate water type.

The two confined-aquifer water samples, as shown by 

their Stiff diagrams (fig. 8), in which the major ion chemistry is not calcium bicarbonate or calcium magnesium bicarbonate type, are sites 6 and 15. Both water samples have 

geochemical characteristics distinct from other samples 

from the Arbuckle-Simpson aquifer. Major ion chemistry 

in water samples from these two wells is predominantly 

sodium and chloride. The composition of these samples 

appears to be a mixture of predominantly typical ArbuckleSimpson calcium magnesium bicarbonate water mixed with 

a small amount of the brine that resides in the aquifer outside 

the freshwater zone. These brines, of which the water sample 

from site 31 (a producing oil well) is typical, are highly 

concentrated and only a small amount in combination with 

Arbuckle-Simpson freshwater is required to produce water 

such as that found in sites 6 and 15. Additional discussion 

of the chemistry of these two wells is found in the section, 

“Vendome Well and Site 6.” 
Geochemical Investigation 23

Test Well

Water samples were collected from zones in the test well 

by using a combination of single and double packers. The 

sampled zones are shown in the following table:

Interval sampled

Zone 1 <195 feet

Zone 2 519–539 feet

Zone 3 1,209–1,229 feet

Zone 4 1,389–1,409 feet

Zone 5 >1,490 feet

Results of the chemical analyses of water samples 

from the five zones in the test well are shown in appendix 1 

(site 32, samples 32, 33, 34, 35, and 36). The water chemistry in the zones was remarkably uniform. The dissolved 

solids concentration ranged from 322 to 332 mg/L, a range 

of only 3 percent. In general, major ion and trace element 

chemistry showed very little variation from the highest to 

lowest interval in the test well. Copper and iron concentrations 

have a considerably larger range than dissolved solids, but 

copper and iron could have been introduced from the drilling 

equipment. 

Borehole flowmeter logs (R. Ross, U.S. Environmental Protection Agency, written commun., 2007) obtained 

after the water samples were collected in the test well 

show downward flow of water in the borehole under nonpumping conditions. When the test well was sampled, the 

packers were set and the well was purged at about 7 gallons 

per minute for a period of over 12 hours, but the sampled 

water possibly was influenced by downward flow during the 

9 months between the drilling of the well and when the well 

was sampled. 

One of the primary purposes for drilling the test well 

was to determine the thickness of the freshwater zone in 

the Arbuckle-Simpson aquifer by drilling deep enough to 

encounter the underlying saline water. Hart (1966) shows 

saline water underlying freshwater everywhere in southern 

Oklahoma, although Hart’s map shows an insufficient number 

of data points in the Arbuckle-Simpson aquifer to determine 

the depth to saline water. Parkhurst and Christenson (1987) 

show that saline waters in Oklahoma generally are sodium 

chloride type water, similar to the water from the oil well 

sampled during this investigation (listed as site 31, sample 31, 

in appendix 1). None of the chemical analyses for the test 

well show any indication of elevated concentrations of sodium 

or chloride. The deepest interval from the test well, zone 5, 

has the lowest sodium concentration and the second lowest 

chloride concentration. Thus, the saline water that is expected 

to underlie the freshwater in the Arbuckle-Simpson aquifer 

probably is deeper than 1,820 feet at the location of the test 

well. 

Geochemical Reactions 

Several geochemical techniques were used to investigate the chemical reactions that occur between the points of 

recharge in the aquifer and the points in the flow path where 

water samples were collected, either wells or springs. Saturation index calculations provide information about dissolution 

or precipitation of carbonate minerals relative to the water 

sample. Carbon-13 isotopic data are used to distinguish 

between processes that occur in the unsaturated zone and those 

that occur in the saturated zone. Inverse geochemical modeling 

is used to account quantitatively for the chemical composition of the water sample by mixing of saline and freshwaters 

and reaction of minerals and gases likely to be present in the 

aquifer. 

Saturation Indices

Interpretation of the chemical analyses from this study 

relies on the use of saturation indices and partial pressures of 

carbon dioxide. The saturation index for a mineral is defined 

to be the log of the ion activity product divided by the equilibrium constant for a mineral dissolution reaction (Appelo 

and Postma, 2005). Given the following reaction for calcite 

dissolution:

CaCO Ca CO 3

2

3

2 = ++ −

, (2)

the calcite saturation index is

SI

a a

K Calcite

Ca CO

Calcite

= 















+ −

log10 2 3

2

, (3)

where 

SI is the saturation index, 

a is the activity of an ion, and 

K is the equilibrium constant. 

The calculation of the log partial pressure of carbon dioxide is 

similar:

log log 10 10 2

2

P

a

K CO

CO

Henry

aq ( ) = 















( ) , (4)

where,

PCO2 is the partial pressure of carbon dioxide, and 

KHenry is the Henry’s law constant for carbon dioxide. 

Saturation indices and carbon dioxide partial pressures were 

calculated with the geochemical model PHREEQC (Parkhurst 

and Appelo, 1999) by using the ion-association aqueous 

model. Saturation indices can be interpreted as follows: If 

the saturation index is greater than zero, the mineral could 

precipitate, but cannot dissolve; if the saturation index is less 
24 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

than zero, the mineral could dissolve, but cannot precipitate; if 

the saturation index is near zero, the mineral could be reacting 

sufficiently fast to attain equilibrium between the mineral and 

the solution. The word “could” is used to indicate that kinetics are involved in the mineral reactions; although reactions 

may be favored thermodynamically, they may proceed rapidly, 

slowly, or not at all, depending on the kinetics of the reaction.

Carbonate Reactions

Water in the aquifer of the three anticlines of the 

Arbuckle-Simpson aquifer is predominantly calcium bicarbonate or calcium magnesium bicarbonate composition that is 

formed by uptake of carbon dioxide in the unsaturated zone 

and reaction with calcite and dolomite in the unsaturated and 

saturated zones. Partial pressures of carbon dioxide in ground 

water range from 0.1 to 0.01 atmosphere with a trend toward 

lower partial pressures with depth (fig. 9C). The partial pressures are greater than atmospheric carbon dioxide (0.0003 

atmosphere) because of generation of carbon dioxide in the 

unsaturated zone by plant respiration and decay of organic 

matter. The downward trend in the partial pressure of carbon 

dioxide with depth can be explained by loss of contact with 

unsaturated-zone carbon dioxide gas and consumption of dissolved carbon dioxide by dissolution of carbonate minerals in 

the saturated zone. 

Ground water in the study area is near saturation with 

calcite (SIcalcite greater than -0.2), whereas water is substantially undersaturated with dolomite [SIdolomite less than -0.4 (a 

larger value is used for dolomite than calcite because of the 

two carbonate ions in the dolomite formula, CaMg(CO3)

2

) 

compared to one carbonate ion in the calcite formula, CaCO3]. 

The undersaturation of dolomite is caused either by absence 

of dolomite in the formations or slow reaction kinetics of 

dolomite. All samples from the Arbuckle Anticline, one 

sample from the Tishomingo Anticline, and one sample from 

the Hunton Anticline have dolomite saturation indices of -1.0 

or less, which may indicate limited availability of dolomite. 

All other samples have dolomite saturation indices of -0.4 or 

greater, which probably indicate water compositions that are 

approaching dolomite saturation with time. Helium-tritium 

dating (see the Ground-Water Dating section of this report) 

indicates that most samples with dolomite saturations of -0.4 

or greater are less than 40 years old. The four samples that are 

more than 40 years old are near saturation with dolomite. 

Carbon-13 

Carbon-13 isotopic data provide insight into the processes affecting carbon that occur in the saturated and unsaturated zones. Carbon-13 is measured as the ratio of the abundance of carbon-13 atoms to carbon-12 atoms relative to the 

ratio in a standard. The data are presented as permil relative 

to the standard and are compared here by using the terms 

lighter (relatively less carbon-13) and heavier (relatively more 

carbon-13). For example, a sample with a negative permil 

value is lighter than the standard, which has a permil value of 

zero. Many processes cause fractionation of carbon-13, which 

means that one of the isotopes (carbon-12 or carbon-13) is 

used preferentially in the process. For example, the distribution of carbonate between aqueous solution and calcite results 

in carbon isotopes in calcite that are heavier than the carbon 

isotopes in solution. 

Carbon dioxide produced by most terrestrial plants (C3 

plants) in the unsaturated zone generally has a carbon-13 

isotopic signature of about -27 permil (Appelo and Postma, 

2005). Differential diffusion between carbon-12 and carbon-13 

causes the gas phase to be heavier (enriched in carbon-13) by 

about 4 permil (Cerling, 1984), resulting in unsaturated zone 

carbon dioxide isotopic composition of about -23 permil. If 

carbonate minerals react to equilibrium in the unsaturated 

zone, the carbon-13 composition of water entering the saturated zone will be in isotopic equilibrium with the unsaturatedzone gas. Equilibrium fractionation between gas and water 

is pH and temperature dependent; at 18 °C and pH 7.0, the 

fractionation factor is about 7 permil (Mook, Bommerson, 

and Staverman, 1974) as calculated by NETPATH (Plummer, 

Prestemon, and Parkhurst, 1994). Thus, the isotopic composition of inorganic carbon in the water will be 7 permil heavier 

than the gas, or about -16 permil. Alternatively, if no carbonate 

minerals dissolve in the unsaturated zone, the fractionation 

factor between gas and water will be about -1 permil and the 

isotopic composition of the dissolved inorganic carbon in the 

water entering the saturated zone will be about -24 permil. If 

carbonate minerals have a typical marine carbonate carbon-13 

composition of about 0 permil and all dissolution occurs in 

the saturated zone, then ground water will have a carbon-13 

composition of about -12 permil (Appelo and Postma, 2005).

The isotopic compositions of the six reconnaissance 

water samples analyzed for carbon-13/carbon-12 ratio are in 

the range of -7.2 to -12.8 (appendix 1). These values tend to 

be heavier than would be expected from the arguments of the 

previous paragraph. One possible explanation for the heavierthan-expected isotopic composition of the ground water is 

dissolution of dolomite with calcite precipitation. The kinetics 

of calcite reactions appear to be faster than that of dolomite, 

as indicated by the saturation indices for calcite generally near 

zero and dolomite less than zero. After the initial dissolution 

of calcite to equilibrium, continued slow dissolution of dolomite will cause precipitation of calcite. Carbon from dolomite 

dissolution will be about 0, which will cause dissolved carbon 

to become heavier, and carbon in the precipitated calcite 

will be about 1 permil heavier than the dissolved carbon-13, 

which will cause the dissolved carbon to become lighter. 

Although these two processes compete, the combined effect 

of dolomite dissolution and calcite precipitation will be to 

drive the carbon-13 composition to heavier values. Thus, 

for ground water in the Arbuckle-Simpson aquifer, the most 

likely sequence of reactions that explains the chemical and 

carbon-13 composition of the water is that carbon dioxide 

is taken up in the unsaturated zone and dissolves the host 
Geochemical Investigation 25

Figure 9. Calcite and dolomite saturation indices and log partial pressure of carbon dioxide.

-0.40 -0.30 -0.20 -0.10 0 0.10

CALCITE SATURATION INDEX

-2.00 -1.75 -1.50 -1.25 -1.00 -0.75 -0.50 -0.25 0

DOLOMITE SATURATION INDEX

-2.00 -1.75 -1.50 -1.25 -1.00 -0.75

LOG PARTIAL PRESSURE OF CARBON DIOXIDE

0

250

500

750

1,000

1,250

1,500

WELL DEPTH, IN FEET

0

250

500

750

1,000

1,250

1,500

0

250

500

750

1,000

1,250

1,500

WELL DEPTH, IN FEET WELL DEPTH, IN FEET

A

B

C
26 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

rock, either limestone or dolomite. The carbon dioxide reacts 

quickly to dissolve calcite in the unsaturated zone, whereas 

dolomite dissolves more slowly. However, dolomite continues 

to dissolve in the saturated zone, with concurrent precipitation 

of calcite. 

Other factors affect the isotopic composition of the 

ground water and may explain the heavy isotope compositions: (1) the carbon-13 of the plants is uncertain; for example, 

-25 permil is often cited (Drever, 1982); (2) isotopic exchange 

may occur between the carbonate rocks and the water; isotopic 

exchange equilibrium would indicate that, given geologic 

time, the carbon-13 of the water should be 1 or 2 permil 

lighter than the source rocks (assumed to be 0); (3) there may 

be an influence of C4 plants (some arid-zone plants), which 

have a carbon-13 signature of about -13 permil (Appelo and 

Postma, 2005); and (4) carbon-13 values heavier than 0 permil 

are possible in diagenetic dolomites. 

Vendome Well and Site 6

The water compositions at the Vendome Well (site 15) 

and site 6 represent old waters that are found at the edges of 

the freshwater aquifer. These two sites were the only sites for 

which carbon-14 ages were calculated because all other waters 

from the aquifer had tritium concentrations that indicated a 

fraction of modern water. Inverse geochemical models were 

calculated by PHREEQC (Parkhurst and Appelo, 1999) to 

account for chemical reactions that affect the carbon-14 

activities of the water samples from Vendome Well and site 

6. Inverse models account for the concentrations of all major 

ions in the evolution from one water composition to another 

by dissolution and precipitation of minerals and gases. The 

inverse modeling accounts for the concentrations of calcium, 

magnesium, sodium, silica, chloride, sulfate, and carbon. To 

simplify results, potassium and nitrogen were not included 

because they were considered to be minor constituents in the 

analyses. PHREEQC allows assignment of uncertainty to the 

analyzed concentrations; for these calculations, an uncertainty 

of 10 percent was applied to all concentrations in all solutions.

The carbon-13 data and the saturation indices indicate 

that calcite dissolves followed by dolomite dissolution and 

calcite precipitation. The inverse models for the two water 

samples were derived by assuming recharge initially equilibrates with calcite. A PHREEQC calculation generated a 

water composition (starting from pure water) with log partial 

pressure of carbon dioxide of -1.7 that was in equilibrium with 

calcite. This partial pressure was selected because no further 

addition or removal of carbon dioxide was needed in modeling the Vendome Well or site 6 samples. It was assumed in 

the inverse models that the water compositions evolved from 

this calcite-saturated solution (representing water recharged to 

the saturated zone) with an admixture of brine, as represented 

by the brine analysis (site 31; appendix 1). The chloride-tobromide mass ratio of the brine (260) is similar to the ratio 

in seawater (287). This similarity indicates that the brine is 

derived from evaporation of seawater, but the evaporation did 

not proceed past the point of precipitating halite (sodium chloride). The saturation index for halite in the brine is -1.6, which 

is consistent with a solution undersaturated with halite. 

In addition to mixing of waters, the inverse modeling 

included the following possible reactants: calcite, dolomite, 

gypsum, sodium feldspar (albite), quartz, and kaolinite. 

Carbon dioxide was not included because the inverse modeling attempted to account only for reactions in the saturated 

zone. Calcite and dolomite can be considered to be present 

throughout the aquifer surrounding the two sampling sites. 

Large sulfate concentrations are apparent in the sample 

analyses and gypsum (or anhydrite) is the most likely reactant. 

Gypsum is not abundant in the aquifer, although traces have 

been identified (Donovan, 1991). Gypsum may be present as 

inclusions within the carbonate minerals of the aquifer, which 

could weather out slowly as the carbonate minerals dissolve 

or recrystallize. Weathering of feldspars to quartz (or chalcedony) and kaolinite is a common process, although the rates 

of weathering may be slow. Feldspars are common minerals 

that are likely to be present in all of the formations of the 

Arbuckle-Simpson aquifer. 

Inverse modeling determined a relatively simple set of 

reactions that account for the compositions of the two water 

samples. Mixing the calcite-saturated recharge water and brine 

and dissolving calcite, dolomite, and gypsum account for 

each of the water compositions (table 6). The mole transfers 

of minerals are similar between the two samples. The primary 

difference between the two models is that Vendome Well has 

a larger mixing fraction of brine, about 1 percent, compared to 

site 6, about 0.5 percent. The mixing fractions also account for 

the concentrations of bromide and iodide in the two samples, 

which are expected to be conservative constituents of the 

brine. Although site 6 is about 25 miles from the Vendome 

Well and from the well where the brine was sampled, the same 

brine composition accounts for the conservative elements in 

the site 6 sample, which indicates a brine of similar composition is likely to be present below the entire freshwater zone of 

the Hunton Anticline part of the Arbuckle-Simpson aquifer. 

The brine component of the sample at Vendome Well is likely 

to account for the relatively large concentrations of many 

of the trace elements (potassium, fluoride, bromide, iodide, 

ammonia, arsenic, boron, lithium, selenium, and strontium).

Table 6. Inverse models for Vendome Well and site 6.

[Mixing fractions are unitless; mole transfers for calcite, dolomite, and 

gypsum are millimoles per liter; negative mole transfers indicate precipitation, 

positive dissolution]

Well

Mixing 

fraction of 

recharge 

water

Mixing 

fraction 

of brine

Mole transfer

Calcite Dolomite Gypsum

Vendome Well 0.991 0.009 -2.36 1.24 0.24

Site 6 .995 .005 -2.45 1.32 .29
Geochemical Investigation 27

If the recharge water is assumed to have carbon-13 of -12 

permil (closed system from Appelo and Postma, 2005), then 

the calculated carbon-13 for the water samples, accounting for 

the inverse modeling reactions, are Vendome Well -8.3 and 

site 6 sample -8.1, compared to measured values of -8.21 and 

-8.44. To obtain this similarity, most dissolution of carbonate 

minerals was assumed to occur in the saturated zone and that 

dissolution of calcite precedes dissolution of dolomite. 

No feldspar weathering reactions were needed in the two 

inverse models, although these reactions are plausible. This 

lack of reaction probably results from two factors. First, feldspar dissolution is expected to be limited, and is likely to be 

insignificant relative to the 10 percent uncertainties assigned 

to the calculation. Similarly, the “minimal” model option was 

used in the calculation, which actively tries to eliminate reactants, if possible, by making concentration adjustments within 

the uncertainty limits. 

The Vendome Well and the site 6 well sample both 

have substantial ammonium concentrations, no nitrate, and a 

smell of hydrogen sulfide. These observations are consistent 

with a reducing environment; however, the fact that some 

sulfate remains in solution indicates that the chemical environment is not extremely reducing. The reduced species may 

be derived from the brine, which is certainly in a reducing 

environment when in the presence of petroleum. Ammonium 

concentrations in the two samples are consistent with dilution 

of the ammonium concentration in the brine (given a 20 percent uncertainty in the analytical data). Alternatively, the water 

discharging at the wells has encountered organic material at 

some point along the flow path that has removed oxygen and 

nitrate, generated ammonium, and produced a slight amount of 

sulfate reduction.

Ground-Water Dating

Ground-water dating refers to the process of measuring 

the amount of time elapsed since a parcel of ground water 

became isolated from the atmosphere. The actual dating of 

water in almost all cases relies on the measurement of a specific tracer that is introduced to the ground water at the water 

table by a known physicochemical or biological process. The 

parcel of water then becomes isolated from the atmosphere 

with subsequent recharge and thus begins to “age.” This measured time component is considered a mean residence time for 

the ground water within an aquifer.

Understanding that there can be vast differences in the 

age of ground water within a given flow system, a simple 

system for classification is commonly used. “Modern” 

ground water is considered to have been recharged within the 

past few decades (after 1950) and are considered part of the 

active hydrological cycle; “sub-modern” water is considerably 

older (pre-dating 1940s) and is defined by the lack of measurable tritium (3

H) in the water. 

Within the context of the Arbuckle-Simpson Hydrology 

Study, ground-water dating is used to evaluate the modern 

ground-water component of the regional flow system. Three 

separate techniques were used: helium-3/tritium (3He/3H), 

chlorofluorocarbons (CFCs), and carbon-14 (14C) techniques. 

Each technique has its strengths and drawbacks within groundwater flow systems, but the techniques can be used in combination to validate assumptions used in ground-water dating.

Helium-3/Tritium Dating

Tritium (3H) is the radioactive isotope of hydrogen, 

which decays by beta decay to helium-3 (3He) with a half-life 

of 12.33 years (Lucas and Unterweger, 2000). Unlike CFCs, 

which rely on solubility conditions to be introduced into 

ground-water systems, 3H originates as part of the water molecule (for example, 3

H-1H-O) and represents an almost perfect, 

conservative tracer. 3H, in the form of water in the atmosphere, 

is mainly associated with atmospheric testing of nuclear weapons that began in 1952 and reached a maximum in 1963–64. 

However, there is a natural production source associated with 

cosmic-ray interaction with nitrogen in the upper atmosphere. 

The nature of the 3

H input (mainly anthropogenic) to the atmosphere produces a spike-like input to an aquifer associated 

with the nuclear testing maximum and a decay curve as the 

initial input goes through radioactive decay to natural production levels. 3

H dating technique is similar to CFCs in that a 

measured concentration can be used to determine age through 

comparison to a historic input curve; however, the real strength 

comes from a separate measurement of 3He contained in the 

ground water to produce an apparent age based on radioactive 

decay of parent isotope to daughter. This technique requires 

two separate samples, one for the measurement of tritiogenic 

helium-3 (3He*, derived from decay of 3H) contained as a dissolved gas in the ground water and the other for the low-level 

measurement of the 3H by 3He in-growth. 

Measurement of 3He* involves the analysis of the dissolved gas contained in a ground-water sample. As precipitation in the form of water enters an aquifer, solubility conditions [temperature, partial pressure (altitude and composition 

of gas), and salinity] present at the water table control the 

amount of dissolved gas present in the ground water. Air, having very uniform composition with respect to the noble gases, 

forms a distinctive dissolved gas composition in equilibrium 

with the ground water. This distinctive composition is termed 

air-saturated water (ASW). By measuring the helium isotopic 

composition (3

He/4He ratio expressed as R/RA [(3He/4Hesample)/ 

(

3

He/4Heatmosphere)]) and concentrations of helium (He), nitrogen 

(N2), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe), 

amounts of 3He associated with solubility conditions and 

excess gas (additional amounts of excess air and/or terrigenic 

helium) can be resolved (Schlosser and others, 1989). The data 

derived from the analysis separates out the various sources of 

3

He contained in the sample and solves for the tritiogenic 3He 

by:

 3

He* = 3Hemeasured – 3Hesolubility – 3Heexair – 3Heterrigenic, (5)
28 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

where 3

He* is tritiogenically derived 3He; 3

Hemeasured is 3He measured in the sample; 3

Hesolubility is 3He associated with recharge temperature, 

salinity, and altitude, derived by bulk 

dissolved gas analysis; 3

Heexair is 3He associated with additional excess air, derived 

by bulk dissolved gas analysis; and 3

Heterrigenic is 3He associated with excess helium either from 

internal production within the aquifer or from 

an external flux into the aquifer.

The measurement of 3H was performed by the 3He 

in-growth method for determinations as low as 0.05 tritium 

unit (TU) (1 TU is 1 3H atom per 1018 hydrogen atoms). The 

method involves degassing a sample of water and sealing the 

degassed water off from the atmosphere within a measuring vessel for a period of 2 to 3 months. The sample is then 

analyzed for the amount of 3

He produced by 3H decay over 

the time period (3He in-growth) and the amount of 3H is then 

calculated (Bayer and others, 1989).

Using the data from both the dissolved gas measurement 

and the tritium analysis, the apparent age of the sample is 

calculated from the following equation:

t = T1/2/ln(2) * ln(1+ (3He*/3H)), (6)

where 

t is the apparent age, in unit time; 

T1/2 is the half-life of 3H, in unit time; and 

3

He*/3H is the measured ratio of 3He* and 3H. 

Chlorofluorocarbons 

CFCs are stable, synthetic organic compounds that were 

first produced in the 1930s and are purely of anthropogenic 

origin in the atmosphere. Since the 1930s CFCs have accumulated in the atmosphere at a quantifiable rate, thus yielding 

a CFC concentration-to-age relation in modern ground water. 

Concentrations within waters are controlled by the solubility 

of the gas in water, which in turn is controlled mainly by the 

partial pressure (altitude and mole fraction) of the constituent 

CFC (CFC-11, CFC-12, and CFC-113) in the atmosphere and 

recharge temperature of the ground water. Simply by measuring the dissolved concentration of a CFC in a water sample, 

an atmospheric concentration can be computed and then 

compared to a known time series of atmospheric concentration to estimate an age for the sample (Plummer, Busenberg, 

and Cook, 2006). Analysis of CFCs is preformed on a gas 

chromatograph fitted with an electron capture detector, which 

allows for the measurement of CFC-11, CFC-12 and CFC-113 

to concentrations as low as 0.3 picograms per kilogram (pg/

kg). This analysis typically produces three complementary 

ages, each associated with a common CFC. For a full explanation see Plummer and Busenberg (1999), Plummer (2005), and 

Plummer, Busenberg, and Cook (2006).

Carbon-14 Dating

Carbon-14 is a naturally occurring radioactive isotope 

that forms in the atmosphere and decays with a half-life of 

5,730 years. To use carbon-14 to estimate ground-water 

ages involves three steps: (1) an estimate of the carbon-14 

activity at the time ground water entered the saturated zone, 

(2) an inverse model defining the quantitative extent of each 

carbon-affecting reaction in the saturated zone, and (3) the age 

calculation. The initial carbon-14 activity (A0) applies to the 

calcite-saturated recharge water that was used in the inverse 

modeling for the Vendome Well and site 6 samples. For calculations in this report, A0

 was specified by the Fontes and 

Garnier (1979) model, using an open-system for soil 

carbon-13 gas of NETPATH (Plummer, Prestemon, and 

Parkhurst, 1994. The adjusted carbon-14 activity accounting 

for reactions (and, for no decay) is derived from the inverse 

modeling of the “Vendome Well and Site 6” section of this 

report. The age calculation is 

t

A

A

nd = ( )





 



 5730

1 2

1

n

n , (7)

where 

t is the age of the sample in years; 

And (no decay) corrects the initial estimate of 14C activity 

(Ao) with reactions of the NETPATH 

inverse models, but not for the decay of 

14C; and 

A is the measured activity of 14C. 

Dating Results

The results of the isotopic and compositional analyses 

for dissolved gas constituents are presented in table 7. Because 

ground water in the Arbuckle-Simpson aquifer consists of 

freshwater infiltrating across a relatively flat area (known 

salinity and partial pressures), the main variable controlling solubility of dissolved atmospheric gas is the recharge 

temperature. Typical recharge temperatures should be close to 

those measured in the shallow aquifer and be related to mean 

annual temperatures for the region (Stute and Sonntag, 1992). 

A comparison of the measured data to known dissolved gas 

concentrations at 16 °C (mean annual temperature from Ada, 

Oklahoma), shows that most samples contain more dissolved 

gas constituents than can be explained by simple solubility 

conditions alone (table 7). The amount of excess dissolved gas 

above that of solubility concentrations could be attributed to 

colder recharge temperatures and/or the addition of excess gas 

to solution. One source of excess dissolved gas is the introduction of excess air during recharge (Heaton and Vogel, 1981). 

Recharging water to a fractured or karstic bedrock aquifer 

typically entraps extra amounts of atmospherically derived gas 

(air) during recharge. This excess air is forced into solution 

with increasing hydrostatic pressure during recharge, giving 
Geochemical Investigation 29

Table 7. Dissolved gas data.

[Dissolved gas data are given in units of gas volume at standard pressure and temperature per unit mass of water; cc, cubic centimeter; kg, kilogram; STP, 

standard temperature and pressure; μcc, micro-cubic centimeter; R/RA, ratio of (ratio of helium-3/helium-4 in sample) to (ratio of helium-3/helium-4 in 

atmosphere); <, less than; NA, not analyzed; ASW, air saturated water; °C, degree Celsius]

Site/sample

number

Nitrogen

(N2)

(cc/kg 

STP)

Methane

(CH4

)

(cc/kg 

STP)

Helium

(He)

(μcc/kg 

STP)

Neon

(Ne)

(μcc/kg 

STP)

Argon

(Ar)

(cc/kg 

STP)

Krypton

(Kr)

(μcc/kg 

STP)

Xenon

(Xe)

(μcc/kg 

STP)

R/

RA

20Neon/

22Neon

40Argon/

36Argon

Nitrogen 

(N2

)/

Argon

1/1 15.10 <0.02 62.1 230.0 0.355 78.8 10.3 0.939 9.85 295.8 42.55

2/2 31.11 <.02 148.1 473.4 .501 99.3 12.7 1.014 9.80 289.8 62.10

3/3 19.08 <.02 81.2 277.6 .434 94.6 12.7 1.324 9.84 295.6 43.95

4/4 22.03 <.02 102.8 309.3 .420 90.2 11.5 1.002 9.86 293.9 52.48

5/5 No sample

6/6 22.33 <.02 8,022.6 282.7 .459 102.5 14.6 .062 9.82 295.2 48.64

7/7 23.09 <.02 107.9 399.4 .460 99.9 13.2 1.018 9.93 295.6 50.18

8/8 16.07 <.02 67.6 276.2 .385 78.1 11.4 1.128 9.85 293.4 41.80

9/9 19.67 <.02 139.7 344.0 .442 93.0 12.2 .765 9.82 293.2 44.47

10/10 17.55 <.02 66.6 280.4 .429 96.5 13.0 1.023 9.91 295.7 40.94

11/11 19.26 <.02 64.7 211.0 .350 81.1 11.0 .983 9.84 293.0 55.03

12/12 16.46 <.02 50.3 203.0 .319 76.3 10.8 .972 9.86 294.0 51.63

13/13 14.67 <.02 57.8 234.9 .366 81.3 11.0 1.251 9.81 295.7 40.06

14/14 24.64 <.02 139.8 325.5 .449 93.0 12.3 .865 9.80 293.6 54.89

15/15 29.02 <.02 21,479 399.3 .518 111.3 12.2 .059 9.80 297.0 56.02

16/16 16.72 <.02 64.5 267.7 .385 85.6 11.4 1.162 9.85 291.7 43.43

17/17 No sample

18/18 15.84 <.02 47.7 197.4 .324 76.9 10.7 1.018 9.85 295.6 48.89

19/19 11.27 <.02 44.8 194.4 .312 73.9 10.0 .970 9.86 294.9 36.09

20/20 14.18 <.02 65.5 234.1 .356 78.9 10.2 .860 9.86 296.0 39.78

21/21 14.61 <.02 59.2 250.1 .359 79.2 10.7 .966 9.91 295.8 40.74

22/22 26.82 <.02 117.8 441.5 .486 95.9 12.2 1.030 NA 295.8 55.20

23/23 No sample

24/24 23.49 <.02 146.4 379.0 .449 92.5 12.3 .834 9.85 296.3 52.28

25/25 16.21 <.02 46.0 190.0 .322 79.3 11.0 .986 9.88 293.3 50.38

26/26 17.80 <.02 65.2 271.6 .380 85.6 11.6 1.001 9.84 296.0 46.87

27/27 No sample

28/28 16.36 <.02 61.8 239.8 .383 88.0 NA 1.203 9.87 296.5 42.68

29/29 No sample

30/30 21.92 <.02 157.3 422.6 .484 94.2 12.2 .752 9.77 295.4 45.33

31/31 No sample

32/32 20.84 <.02 83.0 344.3 .472 98.8 13.0 1.054 9.79 295.6 44.18

32/33 19.69 <.02 88.7 334.2 .445 93.8 12.5 1.307 9.80 296.6 44.24

32/34 Too much dissolved gas, data unresolvable

32/35 44.72 <.02 207.1 828.5 .764 120.8 14.2 1.089 9.79 NA 58.51

32/36 19.69 <.02 81.8 321.7 .418 88.3 11.8 1.267 9.84 293.9 47.10

ASW 16 °C 12.37 <.02 43.7 184.2 .326 74.3 10.4 .980 9.80 295.5 37.94
30 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

a characteristic composition that resembles a mix between 

the solubility and an air-like composition. Aeschbach-Hertig 

and others (1999) further add to this explanation of excess 

gas within samples by demonstrating that the initial excess 

air component may experience partial loss of the excess gas, 

producing a fractionated excess air component. 

Shown in figure 10 are the measured dissolved Ne to Xe 

ratios plotted against Ar for the dissolved gas samples; also 

shown are the modeled data for solubility values (freshwater, 

1,000-foot altitude), excess air, and fractionated excess air 

addition. The plot demonstrates the variations in dissolved 

gas compositions due in large part to the different solubility of each gas in water (Xe>Ar>Ne) and the effect of gain 

and/or loss of excess air. Initial review of the data indicate 

that there appear to be three rough groupings of recharge 

conditions. One grouping has relatively warm (~15 to 20 °C) 

waters that contain little excess air, another grouping has near 

mean annual temperature (16 °C) and follows an excess air 

trend, and a third grouping could be associated with cooler 

than mean annual temperatures and some amount of excess 

air. A majority of the sample data reflect waters that contain 

some form of excess gas introduced during recharge either as 

excess air (Heaton and Vogel, 1981) or fractionated excess air 

(Aeschbach-Hertig and others, 1999). Several of the sample 

EXCESS AIR ADDITION

A=20 cc/kg

A=15 cc/kg

A=10 cc/kg

A=5 cc/kg

A

F=0.8

F=0.4

F=0.6

F=0.2

F=0

F=1.0

EXCESS AIR FRACTIONATION

F

20o

C

15o

C

10o

C

5

o

C

ARGON CONCENTRATION, IN CUBIC CENTIMETERS PER KILOGRAM AT STANDARD TEMPERATURE AND PRESSURE

0.25 0.30 0.35 0.40 0.45 0.50 0.55

RATIO OF NEON TO XENON

10

15

20

25

30

35

40

45

Group and identifier

Relatively warm recharge with little excess air

Near mean annual air temperature (16 degrees Celsius) along excess air trend

Cooler than mean annual air temperature with some excess air

Solubility of air saturated water (ASW) at 5, 10, 15, and 20 degrees Celsius

Excess air trend (A), in cubic centimeters per kilogram (cc/kg) for a sample of ASW at 14 degrees Celsius

Fractionated excess air (F), for a sample with an excess air value (A) of 20 cubic centimeters per kilogram 

at 14 degrees Celsius solubility

Sample

EXPLANATION

I

I

II

III

III II

I

Figure 10. Relation between neon-to-xenon ratio and argon concentration. Model calculations for solubility of air saturated water 

(ASW) at 5, 10, 15, and 20 degrees Celsius (1,000-foot altitude) are displayed on graph. 
Geochemical Investigation 31

sites (5, 17, 23, 27, 29, and 31) are not plotted on this figure 

due to lack of a dissolved gas sample associated with the site, 

although samples 34 and 35 contained too much excess gas 

to be plotted on the figure (table 7). Although a dissolved gas 

analysis was obtained for sample 35, the data plot outside projected norms for the aquifer, indicating that there is contamination in terms of the dissolved gas composition that may have 

been introduced during installation of the well.

Dissolved Gas Modeling

To resolve tritiogenically derived 3He, atmospherically 

derived CFCs, and any terrigenic helium present, the physiochemical conditions associated with recharge must be 

defined. Recharge parameters for this investigation were 

derived by using the bulk dissolved gas analysis for each 

sample (N2, Ne, Ar, Kr, and Xe) and application of the 

closed equilibrium (CE) model after Aeschbach-Hertig and 

others (1999). The CE model incrementally simulates various 

dissolved concentrations on the basis of the parameters 

of atmospheric pressure (altitude), salinity, recharge temperature, excess air, and gas fractionation. A chi-squared test 

(Helsel and Hirsh, 2002) is used to evaluate each incremental step calculation of the model and compare modeled to 

measured concentrations of the dissolved gas components [for 

more complete explanation see Kipfer and others (2002)]. 

This procedure ultimately optimizes the estimates of the physical parameters associated with recharge from the sample 

dataset and provides a chi-squared distribution value that is 

used to evaluate how well the modeled parameters fit the 

dataset. For execution of the dissolved gas modeling, recharge 

parameters of altitude (atmospheric pressure) and salinity 

were assumed to be 305 meters above sea level (1,000 feet 

above the North American Vertical Datum of 1988) and 

0 percent salinity (freshwater), which constrains the CE 

model parameters and allows proper application of the 

chi-squares test. For a complete review of the model and its 

application see Aeschbach-Hertig and others (1999) or Kipfer 

and others (2002).

Results of the dissolved gas modeling are presented in 

table 8. The data agree well with the graphical results in figure 10, with typical chi-square distribution value of less than 

the critical value of 4.0 [as recommended by Kipfer and others 

(2002)], meaning there is no statistically significant difference 

between the data and the dissolved gas model and thus the 

model can be considered to fit the data. Sample numbers 12, 

20, and 25 have chi-squared distribution values that are greater 

than the critical value of 4.0 (6.9, 4.2, and 5.0, respectively) 

but are close enough to the critical value to conclude the 

model may fit the data. Sample 35 did not meet the requirement to pass the chi-square test (the chi-square distribution 

value was 12.1), meaning that a statistically significant difference exists between the data and the dissolved gas model, and 

to conclude the model does not fit the data. As noted previously the amounts of dissolved gas contained in sample 35 

are far higher than would be associated with natural recharge 

conditions, and the sample may be contaminated with respect 

to dissolve gas concentration. 

Resolved recharge temperatures vary greatly within the 

study area. As predicted in figure 10, several samples contain recharge temperatures that are well outside the range 

of temperatures predicted for modern recharge for the area. 

The mean annual air temperature at Ada, Oklahoma, is 16 °C 

and the median temperature of the 30 reconnaissance water 

samples was 18.1 °C. Recharge temperatures for samples 6 

and 15 are clearly too cold (8.2 and 6.6 °C, respectively) to be 

associated with present day temperatures, and recharge temperatures for samples 7 and 10 (10.7 and 9.9 °C, respectively) 

fall between present day recharge temperatures and those of 

samples 6 and 15. Samples 6 and 15 are from the two flowing 

wells producing water from confined parts of the aquifer. The 

colder recharge temperatures are consistent with recharge from 

an earlier, cooler time period. The 6- to 8-degree difference 

is greater than the acceptable value of a 5-degree difference 

for the area (Stute and others, 1992). This may be a result 

of a dissolved gas composition that has undergone a minor 

amount of mass fractionation, which violates the application 

of the CE model. Thus, the CE-modeled recharge temperature 

could be abnormally low and not acceptable as a paleo-climate 

reconstruction (Stute and others, 1992). An explanation for the 

cooler recharge temperatures for water from samples 7 and 10 

is less clear. Both wells are completed in the Simpson Group 

near the edge of the aquifer, in a hydrogeologic environment 

compatible with the possibility that the produced water is a 

mixture of modern and sub-modern water. Of the remaining 

samples, the average recharge temperature is 14.3 +/- 2.2 °C. 

The average temperature is below the mean annual air temperature (16 °C) and the measured ground-water temperatures 

(18.1 °C) from the investigation. The 2-degree difference 

could indicate recharge to the aquifer occurs in the cooler seasons, the noble gas modeling (error propagation of CE model) 

is biased for colder temperatures, or possible sample collection error. Calculating a weighted annual recharge temperature 

based on mean monthly recharge rates [from hydrograph 

separation techniques of stream gage data at Blue River at 

Connerville (Vieux and Calderon, 2005)] and mean monthly 

air temperature at Ada, Oklahoma (table 2), produces a value 

of 14.2 °C. This temperature corroborates the calculated noble 

gas recharge temperatures and indicates that ground-water 

recharge occurs during the cooler months of the year. 

Resolution of terrigenic helium also is defined by the 

CE model. The excess component is determined by subtracting the modeled helium concentration from the measured. 

This component is typically referred to as terrigenic helium 

and represents a non-atmospheric component of helium 

that is derived from either internal production in the aquifer 

(for example, Marine, 1979; Solomon, Hunt, and Poreda, 

1996; Hunt, 2000; Dowling and others, 2004) or an extrinsic 

component that entered the aquifer from an external source 

(for example, Torgersen and Clarke, 1985; and Castro, Stute, 

and Schlosser, 2000). A majority of the investigations into 

terrigenic helium focus on its use as a possible age indicator 
32 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

Table 8. Dissolved gas modeling and helium-3/tritium (3He/3H) age determination.

[°C, degree Celsius; Ae, initial amount of excess air per unit mass of water; cc, cubic centimeter; kg, kilogram; F, fractionation parameter for the CE model; 3

He*, tritiogenically derived helium-3; TU, tritium units; 3H, tritium; μcc, micro-cubic centimeter; STP, standard temperature and pressure; NA, not applicable; 

none*, too much excess helium in sample to resolve 3He*; <, less than; >, greater than] 

Site/

sample

number

Recharge 

temperature

(°C)

Ae

(cc/kg) F

Chi2

distribution

value

3

He*

(TU)

3

H

(TU)

Apparent

age

(years)

Recharge

year

Error

(+/- 

years)

Terrigenic

He

(μcc/kg 

STP)

1/1 17.0 19.44 0.686 2.2 1.79 3.12 8.1 1996.8 0.5 6.2

2/2 13.6 18.99 .069 .2 14.69 3.36 29.9 1974.9 .5 23.8

3/3 12.1 29.51 .576 .8 23.35 3.55 36.0 1968.8 .5 15.0

4/4 14.4 18.44 .384 3.0 15.13 1.43 43.6 1961.3 1.3 26.5

5/5 NA NA 3.13 NA

6/6 8.2 28.73 .597 .8 none* <.05 >60 7,957.2

7/7 10.7 11.22 0 1.6 3.97 2.68 16.2 1988.7 .6 4.5

8/8 14.9 8.45 .298 .9 5.22 2.69 19.2 1985.6 .6

9/9 12.7 12.31 .173 1.3 11.03 2.77 28.6 1976.3 .61 52.82

10/10 9.9 13.36 .461 2.5 1.33 .34 28.3 1976.6 5.1

11/11 13.9 4.11 .618 1.4 7.64 2.89 23.0 1981.8 .6 14.3

12/12 16.3 1.22 0 6.9 0 2.90 <.5 2004.8 .7

13/13 14.2 2.88 .064 1.0 8.49 2.74 25.1 1979.7 .6

14/14 13.9 23.70 .391 0 22.71 1.63 48.1 1956.7 1.2 59.8

15/15 6.6 14.60 .128 0 none* <.05 >60 21,378.6

16/16 14.3 13.01 .474 1.3 6.25 1.72 27.3 1977.6 1.0

17/17 NA NA 2.67 NA

18/18 15.6 .73 0 2.1 .93 2.68 5.3 1999.5 .6

19/19 17.2 .63 0 2.1 <.1 3.12 NA

20/20 16.8 13.35 .622 4.2 .11 3.39 <.5 2004.8 .6 8.7

21/21 16.7 14.31 .578 1.6 <.1 3.51 <.5 2004.8

22/22 13.7 15.16 .028 1.4 2.56 1.07 21.7 1983.1 1.5

23/23 NA NA 4.08 NA

24/24 13.5 12.81 .089 .0 13.40 2.60 32.3 1972.5 .7 48.6

25/25 14.6 .37 0 5.0 .17 3.44 .8 2004.0 .6

26/26 13.8 9.42 .381 1.6 .39 2.69 2.4 2002.4 .7

27/27 NA NA 2.92 NA

28/28 11.8 3.21 0 3.3 7.71 3.48 20.8 1984.1 .4

29/29 NA NA 3.08 NA

30/30 15.3 21.40 .170 .3 5.45 1.17 30.8 1975.1 1.5 48.8

31/31 NA NA NA NA

32/32 12.0 22.64 .354 1.2 2.69 2.69 12.3 1994.2 .5

32/33 12.4 13.58 .243 1.2 18.76 3.03 35.1 1971.4 .6 5.7

32/34 NA NA 3.01 NA

32/35 19.5 62.97 .105 12.1 11.23 2.97 27.8 1978.7 .6

32/36 14.5 13.95 .263 1.6 12.88 3.02 29.6 1976.9 .6
Geochemical Investigation 33

in sub-modern ground waters (for example, Torgersen and 

Clarke, 1985; and Castro, Stute, and Schlosser, 2000) or 

as a tracer to define mantle or crustal flux into geothermal 

and natural gas reservoirs. For this investigation, the amount 

of 3He associated with the isotopic composition of the terrigenic helium component must be defined in order to resolve 

the total amount of tritiogenic 3He (see equation 5) in a 

sample. Typical isotopic compositions of terrigenic helium 

can vary from a radiogenic production ratio (0.02 R/RA, 

Andrews, 1985) to a mixture of mantle-derived helium 

and radiogenically derived helium (~ 0.2 to 8 R/RA). No 

mantle component was assumed to be associated with the 

terrigenic helium for these calculations and the amount of 3He 

correction is calculated by using an isotopic composition of 

0.02 R/RA. About half of the samples measured contain no terrigenic helium, although the other samples contained 6 to 50 

percent terrigenic helium, with two samples (6 and 15) dominated (> 99 percent) by terrigenic helium. For the samples that 

contained moderate amounts of terrigenic helium, the amount 

of terrigenic 3

He only represented about 0.5 percent of the 

total 3He measured; however, samples 6 and 15 contained so 

much terrigenic helium that the tritiogenic 3He component 

could not be accurately resolved. The error associated in the 

estimated terrigenic helium isotopic composition causes either 

too much or too little 3He to be subtracted from the measured 

data, giving unreasonably high or negative values of tritiogenic 

3

He. 

Overall the application of the CE model to the measured 

dissolved gas data produced reasonable estimates for recharge 

parameters, terrigenic helium concentrations, and amounts 

of tritiogenic 3He. The data in table 8 show that a majority of 

samples contain some tritiogenic 3He, which in turn implies 

that the waters must be associated with modern-age waters. 

Samples 6 and 15 show sufficient amounts of terrigenic 

helium at relatively low recharge temperatures to confirm the 

waters are older than modern waters but not necessarily associated with natural gas (lack of methane; table 7). These two 

samples represent extremely old ground waters (on the scale 

of thousands of years of residence time).

Calculated Apparent Age (Mean Residence 

Time)

When dealing with ground-water age determination, the 

absolute age of a sample of ground water is often difficult to 

obtain. Different techniques frequently produce different ages, 

often because of the different assumptions that are associated with specific techniques. For this reason the age from a 

specific technique is referred to as an apparent age. Apparent 

ages from one technique should be similar to apparent ages 

from other techniques as long as assumptions for both techniques are valid; however, often this is not the case. Typically, 

physical factors like the mixing of ground waters of differing 

ages or in-situ degassing can cause ages to be drastically different between one technique and another. This difference in 

apparent age distribution often can be used to determine the 

physical factors (for example mixing or dilution of the tracer) 

through the use of either concentration-based modeling or 

comparison to known inputs of a tracer to other tracers (for 

example, Zuber, 1986; Böhlke, 2006). 

Tritium and Helium-3/Tritium Apparent Ages 

3

H and 3He* data from the samples are listed in table 8; 3

H concentrations are given in TU and 3He* values also have 

been converted to TU for ease in the calculation of age. Samples 6 and 15 had 3

H values below detection limit (0.05 TU), 

which confirm the initial observations from the dissolved gas 

analysis that the samples are sub-modern in age. 

Tritium concentrations in the modern waters range 

between 0.34 and 4.08 TU. This narrow range of 3H concentration limits the use of 3

H as a quantitative age indicator. 

Presented in figure 11 is the 3H input curve derived from 

R.L. Michel (U.S. Geological Survey, written commun., 2008) 

along with a curve that represents the present day values 

calculated from the original 3

H concentrations. The narrow 

range of 3H from the samples places a majority of the samples 

with qualitative recharge dates of 1980 (~ 24 years) to the 

present assuming piston-flow conditions in the aquifer. The 

low tritium concentrations (0.34 TU in sample 10) could be 

related to pre-1960 water. The narrow 3H range in the samples, 

coupled with low 3H level in the present waters, cannot be 

used with accuracy to assess ground-water age. Calculating 

the apparent 3He/3H age from the data shows a broad range of 

ages from 48.1 to less than 0.5 years, quantifying an accurate 

apparent age for the samples. Ten apparent ages are less than 

20 years and 16 are greater than 20 years (excluding samples 6 

and 15). The fact that most sampled ground water was modern 

(apparent age less than 55 years) indicates water is moving quickly from recharge areas to discharge at streams and 

springs.

Plotting the 3He* plus the measured 3H in relation to the 

apparent age should reconstruct the original 3H input curve 

for the area. Figure 12 shows the 3H input curve (R.L. Michel, 

U.S. Geological Survey, written commun., 2008) and the 

measured 3

He* plus 3H plotted against the apparent 3He/3H 

age from the dataset. Most of the data points fall on or within 

error of the dataset; however, several points fall well below the 

input curve. This disagreement, in part, is related to a mixing 

between waters that are devoid of tritium and tritiogenic 3

He 

(sub-modern). Samples from sites 4, 10, 14, 16, and 22 fall 

below the expected 3H input curve and represent a mixture 

between modern and sub-modern waters. Sites 4 and 14 are 

from springs, and site 16 is a well located adjacent to a spring. 

Springs often are the confluence of many flow lines, and the 

geochemical evidence indicates that water samples from these 

sites are mixtures of waters of different origin. Site 10 is a well 

located at the boundary of the aquifer outcrop, and site 22 is a 

well located at the contact between the Arbuckle and Simpson Groups; both wells are located in hydrogeologic settings 

where flow lines may converge and thus are consistent with 

the water samples that are mixtures. 
34 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

Chlorofluorocarbon Apparent Ages

Measured dissolved concentrations for CFC-11, CFC-12, 

and CFC-113 are listed in table 9. As with the 3He data, the 

ultimate composition of dissolved CFC in solution is a result 

of solubility conditions present at the water table. Determination of an apparent age for each measured CFC involves using 

the solubility conditions to estimate the original atmospheric 

concentration, which is compared to a known atmospheric 

curve to assess apparent age of the sample. For 3

He, a closed 

equilibrium model (fractionated excess air) was invoked to 

resolve tritiogenic 3He, but this model currently has not been 

applied to CFCs. One reason for this discrepancy in the use 

of the fractionated or the unfractionated excess air model is 

that CFC concentrations in recharging ground waters may not 

fractionate as much as the helium concentrations due to different solubility. Helium has a low solubility compared to the 

CFCs, and may partially exsolve from solution under certain 

recharge conditions even though the CFCs are quantitatively 

retained. By using the measured dissolved gas data (table 

7), a simple, unfractionated excess air model was applied to 

calculate atmospheric concentrations for the CFC dataset (see 

table 9). Recharge temperature was assumed to be that of the 

calculated CE model, although the amount of excess air was 

calculated to be the original quantity prior to fractionation [see 

CE model (Aeschbach-Hertig and others, 1999)]. Samples 

with no associated dissolved gas sample were assigned an 

arbitrary recharge temperature of 16 °C and 2 cubic centimeters per kilogram of excess air (samples 5, 23, 27, and 29). 

An Excel spreadsheet supplied by the U.S. Geological Survey 

Chlorofluorocarbon Laboratory was used to calculate apparent 

ages by assuming an altitude of 1,000 feet above sea level, no 

local enrichment factor, and the atmospheric input curve from 

Niwot Ridge, Colorado [(Busenberg and Plummer, 2004)—

CFC concentrations SIO-98 scale]. Apparent ages for all three 

CFC compounds are presented in table 9, with a preferred 

apparent age based on laboratory preferences derived from 

CFC analyses. 

CFC apparent age distributions show that a majority 

of the waters are modern in age (post-1950 waters). Only 

samples from sites 6 and 15 contained CFC concentrations 

below detectable limits, which is consistent with the hydrogeology and carbon-14 ages of these sites. However, samples 

10 and 14 are close to the lower detection limits; as previously described, site 10 is a well located near the edge of the 

aquifer, and site 14 is a spring, and both appear to produce 

a fraction of both young and old water. The sample from 

site 5 contained CFC concentrations greater than can be 

Figure 11. Historical measured tritium (3H) values in precipitation (from R.L. Michel, U.S. Geological Survey, written commun., 2008) and 

the calculated 3

H levels present. 

1950 1960 1970 1980 1990 2000 2010

DATE BASED ON HELIUM-3/TRITIUM APPARENT AGE, IN YEARS

10,000

1,000

100

10

1

TRITIUM, IN TRITIUM UNITS

Measured 3H values from the Arbuckle-Simpson aquifer

Range of measured tritium (3H) values

Historical tritium input—Measured value

derived from R.L. Michel (U.S. Geological Survey,

written commun., 2008)

Calculated tritium level present

Error bar—Representing seasonal

variation in historical dataset
Geochemical Investigation 35

explained by atmospheric concentrations and the sample from 

site 1 displayed severe CFC degradation; thus, both apparent age determinations are suspect. Nothing obvious from the 

hydrogeology at sites 1 and 5 explain these anomalies. 

Carbon-14 Apparent Ages

Excluding the brine sample (sample 31), only 7 samples 

were sent to a laboratory for analysis of carbon-14. On the 

basis of helium-3/tritium and CFC dating, all except two 

contained a substantial fraction of young water. The two 

samples of old water were from the Vendome Well and site 

6. Mole-balance models were calculated for the two water 

samples (see “Vendome Well and Site 6” section). The 

adjusted concentrations derived with PHREEQC were entered 

into NETPATH and the inverse model was recreated with the 

additional capability to calculate carbon-14 ages. By using 

the Fontes and Garnier (1979) model in NETPATH for A0

(the initial carbon-14 activity for water entering the saturated 

zone), the apparent carbon-14 ages for the Vendome Well and 

site 6 samples are calculated to be 10,500 years and 34,000 

years. The ages could be about 5,000 years older if an initial 

carbon-14 activity (A0

) of 100 percent modern carbon is used 

instead of the Fontes and Garnier (1979) model.

Comparison of Helium-3/Tritium and 

Chlorofluorocarbon Dating Techniques 

Comparison of two different dating techniques should 

be a fairly straightforward process in which the apparent 

ages calculated from each technique should complement one 

another. This simple concept is not true in all circumstances. 

The overriding assumption for apparent age consistency is 

that the ground water sampled has undergone no physicochemical changes that may alter the tracer concentrations since 

becoming isolated from the atmosphere during recharge, 

other than radioactive decay. In terms of ground-water dating this is termed piston-flow conditions and should generate apparent ages that represent the true residence time of 

the ground water sampled. Processes such as ground-water 

mixing, microbial degradation, sorption, matrix diffusion, hydrodynamic dispersion, contamination (natural and 

anthropogenic), dissolved gas re-equilibration, and improper 

application of technique assumptions (for example, recharge 

temperatures, excess air, or altitude assumptions) can alter 

the calculated apparent age so that different dating techniques 

produce vastly different ages (Cook and others, 2006; Han 

and others, 2006). The process of technique comparison can 

provide insights to natural processes occurring within the 

Figure 12. Comparison of reconstructed initial tritium (tritium [3H] plus tritiogenic helium-3 [3He*]) to historical tritium input levels. 

1950 1960 1970 1980 1990 2000 2010

DATE BASED ON HELIUM-3/TRITIUM APPARENT AGE, IN YEARS

10,000

1,000

100

10

1

TRITIUM, IN TRITIUM UNITS

Historical tritium input—Measured value

derived from R.L. Michel (U.S. Geological Survey,

written commun., 2008)

Sample for reconstructed initial tritium

(tritium [3

H] plus tritiogenic helium-3 [3He*])

and identifier—See table 8

Error bar—Representing error associated with 3

He/3H apparent age for sample

Error bar—Representing seasonal

variation in historical dataset

14

4

16

22

10

16
36 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06 Table 9. Chlorofluorocarbon data and age calculation. [CFC, chlorofluorocarbon; pmol, picomole; kg, kilogram; T, temperature; °C, degree Celsius; A, volume of excess air per unit volume of water; cc, cubic centimeter; pptv, part per trillion by volume of air; cal yr, calender year, age of the sample in years subtracted from the date sampled; heavy CFC deg, observed CFC value heavily degraded, lab reported value; Contam., contaminated - CFC concentration was greater than highest atmospheric concentration; BDL, below detection limit; NS, no sample] Site/ sample number CFC Concentrations in water

T

(°C)

A

(cc/kg)

Calculated CFC air concentrations Apparent CFC ages Recommended

apparent

age

(cal yr)

Average 

CFC-11

(pmol/kg)

Average 

CFC-12

(pmol/kg)

Average 

CFC-113

(pmol/kg)

Average 

CFC-11

(pptv)

Average 

CFC-12

(pptv)

Average 

CFC-113

(pptv)

CFC-11

(cal yr)

CFC-12

(cal yr)

CFC-113

(cal yr)

1/1 2.479 2.115 0.241 17.0 6.1 177.5 561.3 58.0 1981.0 Modern 1987.5 heavy CFC deg

2/2 2.421 2.076 .241 13.6 17.7 146.1 472.9 48.0 1977.0 1988.5 1986.0 1987.3

3/3 2.003 1.219 .112 12.1 12.5 111.7 258.7 20.4 1974.5 1976.5 1979.0 1976.7

4/4 1.110 .586 .065 14.4 11.4 69.8 138.5 13.6 1971.0 1970.5 1976.0 1972.5

5/5 299.015 2.440 .324 16.0 2.0 20,381.7 619.9 73.9 Contam. Contam. 1989.5 1989.5

6/6 BDL BDL BDL7/7 5.076 2.337 .211 10.7 11.2 262.3 463.5 35.4 1989.5 1988.0 1983.5 1988.8

8/8 2.993 3.989 .261 14.9 5.9 193.0 964.4 56.0 1982.5 Contam. 1987.0 1984.8

9/9 2.153 1.440 .185 12.7 10.2 123.9 314.5 35.0 1975.5 1980.0 1983.5 1980.0

10/10 .053 .017 .008 9.9 7.2 2.6 3.2 1.2 1953.5 1947.0 1959.0 1947.0

11/11 2.833 1.999 .258 13.9 1.6 173.0 460.2 52.0 1980.5 1988.0 1986.5 1987.3

12/12 2.998 1.938 .293 16.3 1.2 207.4 499.0 67.9 1984.5 1990.5 1988.5 1989.5

13/13 1.861 1.373 .164 14.2 2.7 115.8 321.6 33.8 1975.0 1980.5 1983.0 1981.8

14/14 .212 .255 .012 13.9 14.4 13.0 58.8 2.4 1961.0 1963.5 1963.5 1962.7

15/15 BDL BDL BDL16/16 .326 .356 .021 14.3 6.8 20.4 83.7 4.3 1963.5 1966.5 1967.5 1965.8

17/17 NS NS NS

18/18 3.014 1.967 .268 15.6 .7 201.4 490.8 59.8 1983.5 1989.5 1987.5 1988.5

19/19 3.105 1.963 .299 17.2 .6 224.5 525.6 72.6 1986.0 1993.0 1989.5 1991.3

20/20 3.009 1.983 .284 16.8 5.1 213.3 521.8 67.5 1985.0 1992.5 1988.5 1990.5

21/21 .984 1.842 .137 16.7 6.0 69.4 482.7 32.4 1971.0 1989.0 1982.5 1985.8

22/22 .616 .436 .038 13.7 14.7 37.4 99.7 7.6 1967.0 1967.5 1972.0 1968.8

23/23 2.713 1.656 .226 16.0 2.0 184.9 420.6 51.5 1982.0 1986.0 1986.5 1986.3

24/24 NS NS NS

25/25 3.547 2.040 .345 14.6 .4 225.3 486.5 72.7 1986.0 1989.5 1989.5 1989.5

26/26 3.525 2.127 .314 13.8 5.8 214.9 489.0 63.2 1985.0 1989.5 1988.0 1988.8

27/27 2.326 1.614 .201 16.0 2.0 158.5 410.1 45.7 1978.5 1985.5 1985.5 1985.5

28/28 2.214 1.973 .218 11.8 3.2 121.5 412.7 39.1 1975.0 1985.5 1984.0 1984.8

29/29 1.666 1.840 .203 16.0 2.0 113.6 467.5 46.3 1974.5 1988.0 1985.5 1986.8

30/30 NS NS NS

31/31 NS NS NS

32/32 NS NS NS

32/33 NS NS NS

32/34 NS NS NS

32/35 NS NS NS

32/36 NS NS NS
Geochemical Investigation 37

aquifer or anthropogenically induced processes that are a 

result of sample extraction from the aquifer (for example, mixing within a well annulus or contamination). Concordance of 

apparent ages from multiple techniques can be used to validate 

an apparent age as an appropriate residence time for modeling 

considerations. 

A simple comparison between the apparent ages from 

the CFCs and 3He/3H techniques from this study show fairly 

large differences. Considering analytical error, physical 

parameter assumptions, and application of solubility models, 

some degree of difference can be expected between the two 

techniques (~ +/- 5 yrs would be acceptable), but there is as 

much as 15 to 29 years difference in some samples, which 

may be unacceptable. As noted from figure 12 (3He* plus 3H 

in relation to apparent age), measured data matched well to 

the tritium input curve (agreement with a piston-flow model) 

with only a few samples plotting below the curve, indicative 

of mixing of 3

H-free water (sub-modern) with modern ground 

water. Understanding that a binary mixture of modern and submodern water may be a cause for the disagreement of CFC and 

3

He/3H apparent ages, this problem was approached by using 

guidelines from Plummer, Busenberg, and Han (2006). By 

plotting the ratio of CFC-12 to 3Hinput in relation to the recharge 

year, the effect of simple mixing of modern and sub-modern 

water (that is, concentration dilution) was eliminated. CFC-12 

was chosen from the CFC analyses due to its chemical stability relative to CFC-113 and CFC-11. Plotted in figure 13 is 

the atmospheric input curve for CFC-12 parts per trillion by 

volume (pptv) normalized to the average 3H input curve (TU). 

Because of the variability of 3H signal caused by seasonality in 

the annual measurements, calculated input curves of CFC-12 

normalized by the seasonal high and low values of 3H also are 

plotted in figure 13. Superimposed on this plot are the measured data from this study, where the calculated atmospheric 

CFC-12 concentration for each sample is normalized to 3H + 3

He* (original 3H input) and plotted in relation to the recharge 

date as determined by the 3He/3H. A majority of the data fall 

within the range of input curves, indicating that piston-flow 

conditions and some binary mixes (modern and sub-modern) 

can explain the dataset, but as observed in figure 12, samples 

4, 10 and 14 fall outside of the curves along with samples 2 

and 3, which were not noted in figure 12.

In the case of the sample from site 10, the data point 

falls well below the expected input curves, which can be 

explained as a result of microbial degradation reducing the 

concentration of CFC-12 (as well as CFC-11 and CFC-113) 

making the CFC age older than the 3

He/3H age. As for samples 

2, 3, 4, and 14, the data are above the input curve, indicating 

either that the CFC-12 is enriched with respect to the calculated 3

H input or that 3H is depleted with respect to CFC-12. 

Samples 2, 3, 4, and 14 contain some amount of terrigenic 

helium associated with mixing with sub-modern waters, but 

this mixing should not affect the CFC-12/3Hinput ratio. The 

relative uniformity of the CFC data discounts the concept of 

a specific contamination (enrichment of the CFC values) of 

the samples, which may indicate either that the correction 

of terrigenic helium is over-correcting 3He* and decreasing 

the 3Hinput value or that some physical or chemical process is 

separating the CFC from 3He and 3H components with time. 

Because the lowest 3He/4He value (0.02 R/RA) associated with 

radiogenic production was used in the correction, the terrigenic helium correction should be conservative in respect to 

3

He loss. The results must be a combination of binary mixing 

of modern waters, dispersion of the 3H signal associated with 

the bomb pulse 3H, or a combination of both. Whether mixing 

or dispersion dominates and how to accurately assess the calculated apparent ages for samples 2, 3, 4, and 14 are unclear at 

this time. As described previously, sites 4 and 14 are springs 

where multiple flow lines converge and mixing is anticipated 

on the basis of the hydrogeology of springs; other lines of geochemical evidence presented in this report also show mixing at 

these springs. 

Terrigenic Helium

Terrigenic helium was measured in samples from sites 1, 

2, 3, 4, 6, 7, 9, 11, 14, 15, 20, 24, 30, and 32 (table 8). In general, terrigenic helium is helium derived from either internal 

production in the aquifer (Solomon, Hunt, and Poreda, 1996; 

and Dowling and others, 2004), external flux of helium to 

the aquifer, mixing with water that is enriched in helium (for 

example, oilfield brine), or combinations of all of these factors. The amount of terrigenic helium does not correlate well 

to apparent 3He/3H age in samples from the Arbuckle-Simpson 

aquifer, which tends to discount the internal flux of helium 

from within the aquifer over short time intervals. Possibly 

terrigenic helium in the Arbuckle-Simpson aquifer is derived 

by the uptake of He from crustal rocks as ground water travels 

along long flow paths deep in the aquifer prior to arriving 

at the sampled site. Terrigenic helium is noted in high concentrations in samples from sites 6 and 15 (7,957.2 and 21,378.6 

micro-cubic centimeters per kilogram, respectively), the 

previously noted flowing wells that contain 3H concentrations 

below detectable limits. The amounts of terrigenic helium 

observed in these two samples are several orders of magnitude 

higher than atmospheric solubility, and the presence of long 

flow paths at sites 6 and 15 are confirmed by the old carbon-14 

ages of water samples from these wells. The presence of 

very large terrigenic helium concentrations adds additional 

evidence that ground water in these water samples flowed 

deep into the aquifer where the ground water picked up 

helium. Attempting to define crustal He flux rate using the 

two apparent carbon-14 ages and terrigenic helium concentrations from samples 6 and 15 does not work well. The data 

contradict the use of terrigenic helium as an age indicator 

(age does not correlate to terrigenic helium concentration) 

and supports that the helium concentrations are influenced by 

mixing with fluids that contain variable amounts of terrigenic 

helium.

Five sites with terrigenic helium (4, 9, 14, 20, and 30) are 

springs. Samples 4 and 14 show the clearest contribution of 

sub-modern ground water (fig. 12). Multiple flow paths often 
38 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

converge at springs, and although the water samples 

from these sites had modern ground-water ages, it seems 

likely from the terrigenic helium in these samples that at 

least some fraction of the water from these springs has flowed 

along a long, deep flow path before it discharged at the 

spring. Of the remaining sites with terrigenic helium, three 

are wells located near discharge areas at the edge of the outcrop of the aquifer (sites 1, 7, and 11), again where multiple 

flow paths (including flow paths from deep in the aquifer) are 

likely to converge. The terrigenic helium in samples 2, 3, 24, 

and 33 (from site 32) indicates that water from these wells 

may include water that traveled along long, deep flow paths, 

similar to the water samples from springs. No obvious hydrogeologic features at the wells from which these samples were 

collected indicate that long, deep flow paths discharge 

at these locations; the only indication comes from the amounts 

of terrigenic helium. Alternatively, some other, unknown 

process may be elevating the He concentration in these water 

samples. 

Summary

A geochemical reconnaissance investigation of the 

Arbuckle-Simpson aquifer was initiated in 2004 to characterize the ground-water quality at an aquifer scale, to describe 

the chemical evolution of ground water as it flows from 

recharge areas to discharge in wells and springs, and to 

determine the residence time of ground water in the aquifer. 

Characterization of aquifer-scale ground-water quality was 

accomplished by (1) collecting 36 water samples from 32 

wells and springs distributed across the aquifer for chemical analysis of major ions, trace elements, isotopes of oxygen and hydrogen, dissolved gases, and age-dating tracers; 

and (2) calculating descriptive statistics by using the results 

of the chemical analyses of the water samples. The chemical analyses also were used as input to geochemical models 

to evaluate the chemical evolution of the water as it moves 

through the aquifer. Age-dating tracers were used to determine 

Figure 13. Comparison of helium-3/tritium (3He/3H) and chlorofluorocarbon (CFC) dating techniques.

DATE BASED ON HELIUM-3/TRITIUM APPARENT AGE, IN YEARS

1950 1960 1970 1980 1990 2000 2010

0.01

1,000

100

10

1

0.1

RATIO OF CHLOROFLUOROCARBON-12, IN PARTS PER TRILLION

CONCENTRATION BY VOLUME IN THE ATMOSPHERE,

TO TRITIUM, IN TRITIUM UNITS (pptv/TU)

0.01

1,000

100

10

1

0.1

Ratio of chlorofluorocarbon-12 to

tritium, in pptv/TU, by seasonal 

variation1

Lowest seasonal value of tritium

Mean value of tritium

Highest seasonal value of tritium

Revised position of samples if 

piston flow was involved

Ratio of chlorofluorocarbon-12

to tritium plus tritiogenic helium-3,

in pptv/TU, measured from samples

Sample and identifier—See tables 8 and 9 10

1

Data from R.L. Michel (U.S. Geological Survey, written commun., 2008) 

produced monthly data for tritium. A maximum, minimum, and mean 

value was generated for each calendar year to represent the seasonal 

variation of tritium input.

2

3 4

14

10

(CFC-12 age 1947)

Springs with high excess helium concentration
Summary 39

the approximate time of recharge and residence time of ground 

water in the aquifer.

In general, the water from wells and springs in the 

Arbuckle-Simpson aquifer is chemically suitable for all 

regulated uses, such as public supplies. Dissolved solids 

concentrations are low, with a median of 347 mg/L and an 

inter-quartile range of 331 to 384 mg/L. Two domestic wells 

produced water with nitrate concentrations that exceeded 

the U.S. Environmental Protection Agency’s nitrate maximum contaminant level (MCL) of 10 mg/L. Samples from 

two wells in the confined part of the aquifer, sites 6 and 15, 

exceeded the secondary maximum contaminant level (SMCL) 

for chloride of 250 mg/L. Samples from these same two wells 

also exceeded the SMCL of 500 mg/L for dissolved solids. 

Water samples from these two wells in the confined part of 

the aquifer are not representative of water samples from the 

other wells and springs completed in the unconfined part of 

the aquifer, and both wells consistently are exceptional when 

considering most aspects of the geochemistry of the ArbuckleSimpson aquifer. No other water samples from the ArbuckleSimpson geochemical reconnaissance exceeded MCLs or 

SMCLs, although not every chemical constituent for which 

the U.S. Environmental Protection Agency has established a 

MCL or SMCL was analyzed as part of the Arbuckle-Simpson 

geochemical investigation.

The major ion chemistry of 34 of the 36 samples indicates the water is a calcium bicarbonate or calcium magnesium bicarbonate water type. Calcium bicarbonate water type 

is found in the western part of the aquifer, where the Arbuckle 

Group is predominantly limestone. Calcium magnesium 

bicarbonate water is found in the eastern part of the aquifer, 

where the Arbuckle Group is predominantly a dolomite. The 

major ion chemistry for these 34 samples is consistent with 

a set of water-rock interactions. Rainfall infiltrates the soil 

zone, where the host rock, limestone or dolomite, dissolves as 

a result of uptake of carbon dioxide gas. Some continued dissolution of dolomite and precipitation of calcite occur as the 

water flows through the saturated zone. 

The major ion chemistry of the two samples completed in 

the confined part of the aquifer indicates the water is a sodium 

chloride type, which is different from water samples from the 

unconfined part of the aquifer. Geochemical inverse modeling 

determined a relatively simple set of reactions that account for 

the compositions of the two water samples. Mixing the calcitesaturated recharge water with brine and dissolving calcite, 

dolomite, and gypsum accounts for each of the water compositions. The mole transfers of minerals are similar between 

the two samples. The primary difference between the two 

models is that site 15, Vendome Well in Chickasaw National 

Recreation Area, has a larger mixing fraction of brine, about 

1 percent, compared to site 6, about 0.5 percent. The mixing 

fractions also account for the concentrations of bromide and 

iodide in the two samples, which are expected to be conservative constituents of the brine. Although site 6 is about 25 miles 

from the Vendome Well and from the well where the brine 

was sampled, the same brine composition accounts for the 

conservative elements in the site 6 sample, which indicates 

a brine of similar composition is present below the entire 

freshwater zone of the Hunton Anticline part of the ArbuckleSimpson aquifer. The brine component of the sample at 

Vendome Well is likely to account for the relatively large concentrations of many of the trace elements (potassium, fluoride, 

bromide, iodide, ammonia, arsenic, boron, lithium, selenium, 

and strontium).

Carbon-14, helium-3/tritium, dissolved gas, and chlorofluorocarbons were used to calculate ground-water ages, 

recharge temperatures, and mixtures of ground water in the 

Arbuckle-Simpson aquifer. Based on multiple age-dating 

tracers, 34 of 36 water samples collected to characterize 

the aquifer-scale water quality recharged the aquifer after 

1950. Consistency between chlorofluorocarbon and helium-3/

tritium age tracers within the samples support the concept that 

ground-water flow is characterized by piston-flow conditions 

with relatively young ages (post-1950s waters). The fact that 

most of the sampled ground water was modern (less than 55 

years) indicates that water is moving quickly from recharge 

areas to discharge to streams and springs. Two exceptions to 

this classification were noted in samples 6 and 15. Groundwater ages determined at these two sites by using carbon-14 

are 34,000 years (site 6) and 10,500 years (site 15). 

Concentrations of dissolved argon, neon, and xenon 

in water samples were used to determine the temperature of 

the water when it recharged the aquifer. Resolved recharge 

temperatures vary greatly within the study area. The mean 

annual air temperature at Ada, Oklahoma, is 16 °C and the 

median temperature of the 30 reconnaissance water samples is 

18.1 °C. The average recharge temperature of most samples is 

14.3 +/- 2.2 °C, which is below the mean annual air temperature (16 °C). The 2-degree difference could indicate recharge 

to the aquifer occurs in the cooler seasons, the noble gas 

modeling (error propagation of CE model) is biased for colder 

temperatures, or possible sample collection error. Calculating a weighted annual recharge temperature based on mean 

monthly recharge rates, from hydrograph separation techniques of stream gage data at Blue River at Connerville, and 

mean monthly air temperature at Ada, Oklahoma, produces 

a value of 14.2 °C. This recharge temperature corroborates 

the calculated noble gas recharge temperatures and indicates 

that recharge occurs during the cooler months of the year. 

Recharge temperatures of water samples from sites 6 and 15, 

the two flowing wells producing water from confined parts of 

the aquifer, are clearly too cold (8.2 and 6.6 °C, respectively) 

to be associated with present day temperatures. The colder 

recharge temperatures are consistent with the ground-water 

ages for these samples (34,000 years for site 6 and 10,500 

years for site 15), indicating recharge from an earlier, cooler 

time period, coupled with possible mass fractionation of the 

noble gases that decreases the overall recharge temperature. 

Recharge temperatures for water samples from sites 7 and 10 

also are colder than anticipated, 10.7 and 9.9 °C, respectively. 

Both wells are completed in the Simpson Group near the 

edge of the aquifer, in a hydrogeologic environment where 
40 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06

produced water may be a mixture of modern and sub-modern 

water. 

Terrigenic helium was measured in samples from some 

wells and springs. Terrigenic helium in water samples from the 

Arbuckle-Simpson aquifer is probably derived by the uptake 

of helium from crustal rocks, such as the igneous rocks that 

underlie the aquifer. Ground water that travels deep in the flow 

system may pick up terrigenic helium from these rocks prior 

to arriving at the sampled site. Terrigenic helium is in high 

concentrations from samples at sites 6 and 15. The amounts 

of helium observed in these two samples are several orders of 

magnitude higher than atmospheric solubility, and the presence of long flow paths at sites 6 and 15 are confirmed by the 

old carbon-14 ages of water samples from these wells. Five 

sites with terrigenic helium concentrations are springs in the 

Hunton Anticline part of the aquifer. Multiple flow paths often 

converge at springs, and although the water samples from 

these sites had modern ground-water ages, it seems likely from 

the terrigenic helium in these samples that at least some fraction of the water from these springs has flowed along a long, 

deep flow path before being discharged at the spring. 

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Appendix

Appendix 1
Blank Page
Appendix 1

45

Appendix 1. Site information and chemical analyses for Arbuckle-Simpson Hydrology Study sites.[USGS, U.S. Geological Survey; NAD83, North American Datum of 1983; --, no data; <, less than; >, greater than; μS/cm, microsiemens per centimeter; °C, degree Celsius; mg/L, milligrams per liter; CaCO3, 

calcium carbonate; N, nitrogen; E, detected analytes with concentrations between the long-term method detection level and the laboratory reporting level are reported as estimated by the U.S. Geological Survey’s National Water Quality Laboratory because a detection in this region should have a <1-percent probability of being a false positive (Childress and others, 1999); P, phosphorus; μg/L, micrograms per liter]

Site/

sample

number

USGS site

identification

number

County Local descriptor Latitude (NAD83) Longitude (NAD83) Altitude (feet) Well depth (feet) Interval sampled (feet) Spring name Geologic unit

1/1 342233097110301 Carter 02S-01E-22 ABB 1 34.376 -97.184 1,130 122 Simpson2/2 343008096515301 Johnston 01S-04E-03 ACA 1 34.502 -96.865 1,247 230 Arbuckle3/3 342654096454001 Johnston 01S-05E-27 AAB 1 34.449 -96.762 1,105 267 Arbuckle4/4 342726096400601 Johnston 01S-06E-22 BCC 1 34.457 -96.669 1,000 -- Nelson Spring Arbuckle

5/5 342631096381301 Johnston 01S-06E-26 ADD 1 34.442 -96.637 1,125 125 Arbuckle

6/6 342722096325501 Johnston 01S-07E-23 BCC 1 34.456 -96.549 865 1,400 Simpson7/7 342415096480301 Johnston 02S-05E-08 ABB 1 34.404 -96.801 1,010 110 Simpson8/8 342341096384001 Johnston 02S-06E-11 DBC 1 34.395 -96.644 962 170 Arbuckle9/9 342254096425501 Johnston 02S-06E-18 CAA 1 34.382 -96.716 925 -- Spring Creek Spring Arbuckle

10/10 342441096355301 Johnston 02S-07E-05 CBA 1 34.411 -96.598 955 143 Simpson

11/11 342307096355801 Johnston 02S-07E-17 BCB 1 34.385 -96.599 915 175 Arbuckle

12/12 341933096534201 Johnston 03S-04E-04 BCD 1 34.326 -96.895 975 88 Arbuckle

13/13 342701097121801 Murray 01S-01E-21 CDD 1 34.451 -97.205 1,190 19 Arbuckle

14/14 07329849 Murray 01S-03E-01 ABB 1 34.505 -96.941 1,081 -- Antelope Spring Arbuckle

15/15 343020096582301 Murray 01S-03E-03 ABA 1 34.506 -96.973 949 775 Arbuckle

16/16 342744096563101 Murray 01S-03E-24 BAA 1 34.462 -96.942 1,080 162 Simpson

17/17 342946096535701 Murray 01S-04E-05 DAD 1 34.496 -96.899 1,159 130 Arbuckle

18/18 342848096535001 Murray 01S-04E-09 CCB 1 34.480 -96.898 1,138 33 Simpson

19/19 342440097103001 Murray 02S-01E-02 CBA 1 34.411 -97.175 1,100 -- Bitter Enders Spring Arbuckle

20/20 342425097171201 Murray 02S-01W-03 CCD 1 34.407 -97.287 1,235 -- Cold Spring Arbuckle

21/21 342302097080401 Murray 02S-02E-18 BDB 1 34.385 -97.135 1,190 220 Arbuckle

22/22 342326096583901 Murray 02S-03E-10 CDD 1 34.391 -96.978 1,000 120 Simpson

23/23 342347096530101 Murray 02S-04E-09 DAB 1 34.397 -96.884 1,085 50 Arbuckle

24/24 342101096531701 Murray 02S-04E-28 DCB 1 34.350 -96.889 1,070 300 Arbuckle

25/25 343232096462001 Pontotoc 01N-05E-22 CBB 1 34.542 -96.773 1,135 153 Arbuckle

26/26 343351096430201 Pontotoc 01N-06E-07 CDC 1 34.564 -96.717 1,150 180 Arbuckle

27/27 343137096362701 Pontotoc 01N-07E-30 DBB 1 34.527 -96.608 1,105 300 Simpson

28/28 343839096481101 Pontotoc 02N-05E-17 BDD 1 34.644 -96.803 1,182 275 Arbuckle

29/29 343541096420901 Pontotoc 02N-06E-32 CBC 1 34.597 -96.703 1,138 136 Arbuckle

30/30 07334200 Pontotoc 02N-06E-34 CCD 1 34.595 -96.666 1,022 -- Byrds Mill Spring Arbuckle31/31 342938097024401 Murray 01S-02E-01 DCB 1 34.494 -97.045 990 3,890 3,782–3,876 Simpson32/32 342658096391001 Johnston 01S-06E-23 CCC 1 34.449 -96.653 1,010 1,820 <195 Arbuckle32/33 342658096391002 Johnston 01S-06E-23 CCC 2 34.449 -96.653 1,010 1,820 519–539 Arbuckle

32/34 342658096391003 Johnston 01S-06E-23 CCC 3 34.449 -96.653 1,010 1,820 1,209–1,229 Arbuckle

32/35 342658096391004 Johnston 01S-06E-23 CCC 4 34.449 -96.653 1,010 1,820 1,389–1,409 Arbuckle32/36 342658096391005 Johnston 01S-06E-23 CCC 5 34.449 -96.653 1,010 1,820 >1,490 Arbuckle
46 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06 Appendix 1. Site information and chemical analyses for Arbuckle-Simpson Hydrology Study geochemical reconnaissance sites—Continued. Site/sample number Sample date (yyyymmdd) Sample time Specific conductance (μS/cm) pH Temperature (°C) Dissolved oxygen (mg/L) Alkalinity (mg/L as CaCO3

)

Dissolved

solids

(mg/L)

Calcium

(mg/L)

Magnesium

(mg/L)

1/1 20041021 1100 597 6.9 18.7 4.7 298 347 115 8.112/2 20041018 1500 860 6.9 18.4 7.1 348 494 95.8 49.63/3 20041022 1100 624 6.9 18.3 7.7 329 353 80.8 39.64/4 20041103 1100 517 7.1 17.5 7.5 341 344 73.2 38.95/5 20041021 1230 874 6.7 18.4 3.2 443 478 104 55.16/6 20041021 1000 1,350 7.2 18.4 1.6 258 768 84.8 38.77/7 20041020 1000 600 7.0 16.1 3.7 328 341 79.9 34.58/8 20041019 1000 687 7.0 18.5 4.9 328 351 74.8 39.19/9 20041104 1400 641 7.0 17.4 6.7 358 357 76.7 42.3

10/10 20041104 1000 568 7.2 18.1 1.6 297 329 71.1 31.411/11 20041021 1500 681 6.8 19.5 5.7 338 332 78.1 38.412/12 20041022 1030 654 6.9 19.5 5.8 323 331 100 23.013/13 20041020 1600 547 6.7 19.8 4.7 326 336 96.5 24.814/14 20041020 1200 635 7.1 17.8 .5 315 342 79.1 35.415/15 20041020 1000 2,100 7.1 19.6 .1 278 1,250 86.6 37.416/16 20041020 1500 782 6.9 18.2 3.3 365 424 85.8 47.617/17 20041018 1500 719 6.7 19.1 7.6 348 384 100 30.018/18 20041020 1300 752 6.7 18.3 4.2 333 478 133 16.119/19 20041021 1300 620 6.8 17.9 8.2 325 361 134 4.9720/20 20041105 1600 603 6.8 18.0 6.1 319 358 121 7.3121/21 20041021 900 591 7.0 18.6 .7 308 337 121 6.96

22/22 20041019 1100 377 7.1 18.6 4.0 179 222 77.5 3.1323/23 20041019 1300 634 6.8 20.6 5.6 303 361 79.7 33.124/24 20041019 1600 570 7.0 18.9 7.0 283 305 70.4 33.225/25 20041103 1400 492 7.0 16.7 7.5 256 291 63.2 26.326/26 20041019 1300 616 7.0 19.1 6.5 288 301 67.6 35.227/27 20041019 1600 693 6.8 18.8 5.7 333 353 108 19.328/28 20041018 1000 669 7.0 18.4 3.5 296 322 76.9 35.429/29 20041105 1000 772 6.7 17.7 1.1 546 628 118 77.530/30 20051110 1300 602 7.1 18.2 -- 330 322 73.1 36.6

31/31 20051201 1200 122,000 6.5 33.1 -- 172 88,600 3,600 1,220

32/32 20060724 0900 556 7.1 22.2 6.0 300 322 74.9 38.132/33 20060724 0900 579 6.9 19.0 6.5 314 326 74.0 40.3

32/34 20060725 1600 586 7.0 19.7 10.6 317 323 75.1 40.032/35 20060726 1300 594 7.0 21.0 9.2 322 332 73.3 37.032/36 20060728 1200 572 7.0 20.3 6.0 317 323 72.9 38.7
Appendix 1

47

Appendix 1. Site information and chemical analyses for Arbuckle-Simpson Hydrology Study geochemical reconnaissance sites—Continued. 

Site/sample

number

Sodium

(mg/L)

Potassium

(mg/L)

Bicarbonate

(mg/L)

Carbonate

(mg/L)

Sulfate

(mg/L)

Chloride

(mg/L)

Fluoride

(mg/L)

Bromide

(mg/L)

Iodide

(mg/L)

Silica

(mg/L)

Nitrite

(mg/L as N)

1/1 12.0 0.92 363 0 19.0 2.79 0.2 0.04 E0.002 11.9 <0.008

2/2 20.4 1.67 424 0 31.5 28.3 .2 .14 E.003 9.49 <.008

3/3 4.93 .79 401 0 10.8 8.37 .1 .08 E.001 9.79 <.008

4/4 2.17 1.20 415 0 4.9 2.27 .2 <.20 E.001 10.7 <.008

5/5 8.66 1.58 540 0 17.1 9.82 .1 .09 E.003 9.51 <.008

6/6 141 9.52 314 0 39.9 279 .7 .96 .034 12.4 <.008

7/7 3.82 .84 400 0 11.7 3.27 .2 .05 <.004 12.4 <.008

8/8 3.62 2.52 400 0 9.1 6.69 E.1 .07 E.003 7.86 <.008

9/9 2.15 .81 436 0 5.8 2.43 .1 E.12 E.001 10.5 <.008

10/10 7.32 1.42 362 0 16.6 5.17 .2 .14 .003 13.3 <.008

11/11 1.61 .38 412 0 6.5 1.81 E.1 .05 E.002 9.01 <.008

12/12 1.73 .47 394 0 5.5 1.42 .2 E.02 E.002 9.05 <.008

13/13 1.63 .82 398 0 7.1 1.72 E.1 .04 E.001 9.26 <.008

14/14 3.37 1.48 384 0 16.9 3.35 .1 .04 <.004 11.8 <.008

15/15 316 9.60 339 0 35.1 558 .7 2.08 .062 13.0 <.008

16/16 11.0 2.11 445 0 35.3 15.0 .2 .18 .003 12.9 <.008

17/17 8.33 .96 424 0 9.5 4.10 .1 .05 E.002 11.3 <.008

18/18 13.2 12.8 406 0 49.2 17.2 .2 .12 E.002 13.2 <.008

19/19 1.81 .53 397 0 8.5 1.61 .1 .05 E.001 10.4 <.008

20/20 1.50 .46 390 0 14.9 1.22 .2 <.20 E.001 9.81 <.008

21/21 3.06 .91 375 0 6.6 3.32 .2 .04 E.001 11.0 <.008

22/22 3.15 .37 218 0 12.3 2.94 .1 .07 E.001 9.97 <.008

23/23 3.88 11.4 369 0 7.5 5.65 E.1 .03 .005 14.0 <.008

24/24 4.09 1.10 345 0 8.2 6.26 .1 .05 E.001 9.15 <.008

25/25 1.97 3.52 313 0 10.7 2.28 .1 -- .002 10.4 <.008

26/26 1.18 .78 351 0 5.5 1.85 E.1 .05 E.002 8.82 <.008

27/27 3.38 .58 406 0 11.5 2.71 .1 .03 E.001 9.81 <.008

28/28 5.81 2.03 361 0 15.2 13.4 .2 .07 E.002 9.54 <.008

29/29 7.97 2.47 666 0 50.6 10.8 .2 .28 .007 13.2 <.008

30/30 4.20 1.51 401 0 8.2 3.93 .1 .04 <.002 12.3 <.008

31/31 27,300 280 209 0 <18.0 54,400 .5 173 5.94 9.68 <.008

32/32 2.11 1.42 365 0 8.3 3.18 .1 E.01 .002 8.53 E.001

32/33 1.80 1.06 382 0 5.0 2.23 E.1 E.01 <.002 9.00 <.002

32/34 1.94 1.20 386 0 5.4 1.98 E.1 <.02 <.002 9.30 E.001

32/35 2.14 1.18 391 0 5.9 2.35 .1 E.01 E.001 9.22 .006

32/36 1.77 1.03 386 0 5.2 2.06 E.1 E.01 <.002 8.98 <.002
48 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06 Appendix 1. Site information and chemical analyses for Arbuckle-Simpson Hydrology Study geochemical reconnaissance sites—Continued. Site/sample number Nitrite + nitrate (mg/L as N) Ammonia (mg/L as N) Orthophosphate (mg/L as P) Aluminum (μg/L) Antimony (μg/L) Arsenic (μg/L) Barium (μg/L) Beryllium (μg/L) Boron (μg/L) Cadmium (μg/L) Chromium (μg/L) Cobalt (μg/L) 1/1 1.05 <0.04 <0.02 <2 <0.20 <0.2 71 <0.06 52 <0.04 <0.8 0.373 2/2 14.4 <.04 <.02 <2 <.20 E.1 99 <.06 19 .04 <.8 .247 3/3 4.15 <.04 <.02 <2 <.20 <.2 213 <.06 17 <.04 <.8 .221 4/4 .76 <.04 <.04 <2 <.20 .5 47 <.06 14 <.04 <.8 .152 5/5 2.23 <.04 <.02 <2 <.20 E.1 64 <.06 21 <.04 <.8 .347 6/6 <.06 .3 <.02 <2 <.20 .2 79 <.06 321 <.04 <.8 .270 7/7 .60 <.04 <.02 <2 <.20 E.2 45 <.06 17 <.04 <.8 .189 8/8 5.47 <.04 <.02 <2 <.20 <.2 46 <.06 16 <.04 <.8 .198 9/9 .71 <.04 <.04 <2 <.20 E.2 44 <.06 13 <.04 2.4 .268 10/10 .07 <.04 <.02 <2 <.20 .4 62 <.06 22 <.04 <.8 .160 11/11 .59 <.04 <.02 <2 <.20 <.2 36 <.06 12 <.04 <.8 .209 12/12 .42 <.04 <.02 <2 <.20 E.1 59 <.06 11 <.04 <.8 .266 13/13 .47 <.04 <.02 <2 <.20 E.1 45 <.06 11 <.04 <.8 .263 14/14 .17 <.04 <.02 <2 <.20 E.1 171 <.06 18 E.03 <.8 .177 15/15 <.06 .43 <.02

M <.20 .5 202 <.06 496 <.04 <.8 .310

16/16 1.14 <.04 <.02 <2 <.20 .2 51 <.06 24 <.04 <.8 .22317/17 14.4 <.04 <.02 <2 <.20 <.2 240 <.06 18 <.04 <.8 .30518/18 5.32 <.04 .02 <2 <.20 .3 79 <.06 17 E.03 <.8 .319

19/19 .17 <.04 <.02 <2 <.20 E.1 88 <.06 12 <.04 <.8 .38920/20 .16 <.04 <.04 E1 <.20 E.2 95 <.06 14 <.04 <.8 .26521/21 E.04 <.04 <.02 <2 <.20 E.1 83 <.06 15 <.04 <.8 .34122/22 1.26 <.04 <.02 E1 <.20 <.2 35 <.06 12 <.04 <.8 .19423/23 7.60 <.04 <.02 <2 <.20 .4 47 <.06 21 <.04 <.8 .26224/24 2.61 <.04 E.01 <2 <.20 E.1 51 <.06 15 <.04 <.8 .18325/25 1.20 <.04 E.02 6 E.15 .3 57 <.06 21 .88 E.7 .17926/26 2.59 <.04 <.02 <2 <.20 <.2 38 <.06 11 <.04 <.8 .21227/27 2.61 <.04 E.01 <2 <.20 E.2 60 <.06 11 <.04 <.8 .28628/28 1.23 <.04 <.02 <2 <.20 <.2 88 <.06 26 E.03 <.8 .185

29/29 2.95 <.04 <.04 <2 <.20 E.2 119 <.06 19 E.03 <.8 .34530/30 .88 <.04 <.02 <2 <.20 .45 51 <.06 20 E.02 .13 <.0431/31 <.06 36.6 <.09 <133 <10.0 <2.0 29,800 <4.98 7,080 5.55 <.68 4.7532/32 .95 .022 E.006 <2 <.20 .49 39 <.06 17 E.03 .09 1.632/33 .70 <.010 E.006 <2 <.20 .28 40 <.06 12 <.04 .12 .0732/34 .69 E.008 .009 <2 <.20 .19 43 <.06 13 <.04 1.4 .4532/35 .77 .013 .009 -- E.12 E.09 42 <.06 16 .05 1.6 .69

32/36 .70 E.008 E.006 <2 <.20 .24 39 <.06 13 E.02 .16 .41
Appendix 1

49

Appendix 1. Site information and chemical analyses for Arbuckle-Simpson Hydrology Study geochemical reconnaissance sites—Continued. 

Site/sample

number

Copper

(μg/L)

Iron

(μg/L)

Lead

(μg/L)

Lithium

(μg/L)

Manganese

(μg/L)

Molybdenum

(μg/L)

Nickel

(μg/L)

Selenium

(μg/L)

Silver

(μg/L)

Strontium

(μg/L)

Thallium

(μg/L)

1/1 1.6 14 <0.08 5.2 7.3 <0.4 0.58 <0.4 <0.2 287 <0.04

2/2 2.2 <6 .14 E.6 E.1 <.4 1.80 .5 <.2 67.2 E.03

3/3 5.4 <6 .37 1.2 <.2 E.2 .45 <.4 <.2 64.7 <.04

4/4 E.3 <6 <.08 1.0 E.1 .8 .77 <.4 <.2 53.8 <.04

5/5 5.9 <6 .76 1.0 <.2 <.4 1.18 E.4 <.2 67.6 <.04

6/6 .7 18 <.08 37.9 .9 <.4 1.22 1.1 -- 2,480 <.04

7/7 .9 <6 <.08 1.1 <.2 E.2 1.11 .9 <.2 83.2 <.04

8/8 2.9 <6 .23 E.3 <.2 <.4 .70 <.4 <.2 42.3 <.04

9/9 E.4 <6 <.08 1.0 <.2 E.3 .87 E.3 <.2 62.7 <.04

10/10 4.9 E4 .28 4.7 .4 4.0 .99 1.7 <.2 113 <.04

11/11 2.8 <6 .30 <.6 <.2 <.4 .60 <.4 <.2 62.1 <.04

12/12 6.1 <6 .25 2.2 <.2 <.4 .66 <.4 <.2 165 <.04

13/13 1.6 <6 E.08 .7 .5 <.4 .57 <.4 <.2 78.3 <.04

14/14 .4 <6 .93 1.4 E.2 2.9 1.85 .8 <.2 84.0 .09

15/15 1.2 <18 <.08 66.2 2.2 <.4 1.57 2.5 <.2 6,860 <.04

16/16 9.5 <6 .34 3.2 1.1 1.2 .67 .6 <.2 123 <.04

17/17 2.8 <6 .19 .9 <.2 <.4 1.86 <.4 <.2 67.9 <.04

18/18 3.8 <6 <.08 1.1 1.1 <.4 1.84 .9 <.2 176 <.04

19/19 .6 <6 <.08 2.3 .3 <.4 .74 <.4 <.2 441 <.04

20/20 .5 <6 <.08 3.7 <.2 E.2 1.19 E.3 <.2 1,350 <.04

21/21 5.8 <6 .91 1.8 1.5 <.4 .52 <.4 <.2 163 <.04

22/22 1.0 10 E.05 .9 1.3 E.2 .51 <.4 <.2 68.6 <.04

23/23 3.7 <6 .13 1.1 <.2 <.4 1.19 E.4 <.2 156 <.04

24/24 1.6 <6 .14 1.0 <.2 E.4 .45 E.3 <.2 111 <.04

25/25 2.6 12 .50 E.3 1.2 E.3 2.26 <.4 <.2 42.7 <.04

26/26 1.4 <6 .21 <.6 <.2 <.4 .65 <.4 <.2 22.6 <.04

27/27 3.2 <6 .10 1.2 E.2 <.4 <.06 E.4 <.2 76.3 <.04

28/28 1.1 11 E.06 1.1 .7 .9 1.65 E.2 <.2 71.8 <.04

29/29 22.2 19 .19 .8 3.3 <.4 2.08 E.4 <.2 86.4 <.04

30/30 <.40 <6 <.08 1.7 E.1 1.5 .48 .4 <.2 161 .04

31/31 50.0 1,170 <4.00 4,490 268 <20.0 32.2 4.1 E11.3 206,000 <2.00

32/32 .78 78 <.08 2.0 248 3.9 8.0 4.6 <.2 80.5 E.03

32/33 1.4 88 E.06 .8 10.9 .5 .46 .23 <.2 50.8 <.04

32/34 24.9 11 E.04 1.1 26.6 1.0 1.1 .33 <.2 62.3 <.04

32/35 66.2 9 2.61 1.9 47.8 1.6 1.9 .26 <1.0 68.8 <.04

32/36 10.9 30 .32 .8 17.2 .8 1.1 .25 <.2 50.4 E.02
50 Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06 Appendix 1. Site information and chemical analyses for Arbuckle-Simpson Hydrology Study geochemical reconnaissance sites—Continued. Site/sample number Vanadium (μg/L) Zinc (μg/L) Carbon-14 (percent modern) Carbon-13/carbon-12 (ratio, permil) Deuterium/protium ratio (permil) Oxygen-18/oxygen-16 ratio (permil) Uranium (natural, μg/L) 1/1 E0.1 10.5 95.85 -9.51 -29.5 -4.94 0.37 2/2 1.0 21.1 -29.7 -5.26 .37 3/3 .5 2.9 -29.0 -4.93 .35 4/4 .5 E.5 -29.9 -5.07 .79 5/5 1.1 4.1 -30.6 -5.21 .25 6/6 <.3 E.5 .670 -8.44 -31.6 -5.57 <.04 7/7 .6 1.8 99.80 -12.79 -27.7 -5.05 .86 8/8 .7 13.2 -30.2 -5.26 .18 9/9 .7 <.6 -29.4 -5.20 .44 10/10 .6 1.0 -28.2 -5.24 .67 11/11 .6 4.0 -29.2 -5.08 .29 12/12 1.0 6.0 -25.5 -4.67 .32 13/13 1.1 2.5 -33.5 -5.64 .45 14/14 .2 6.4 66.25 -7.20 -28.8 -5.06 1.67 15/15 <.1 .6 11.97 -8.21 -31.2 -5.40 <.04 16/16 .4 3.9 -27.6 -4.56 .67 17/17 .5 30.9 -29.9 -5.41 .33 18/18 .3 11.7 -30.5 -5.35 1.00 19/19 1.0 <.6 -30.4 -5.28 .34 20/20 1.0 <.6 -30.6 -5.34 .36 21/21 .8 11.5 -35.6 -5.83 .45 22/22 E.1 9.0 -27.8 -4.97 .35 23/23 2.8 1.3 -24.0 -4.23 .15 24/24 1.1 1.6 -27.9 -4.89 .26 25/25 1.1 196 -35.2 -6.39 .18 26/26 1.3 1.7 -28.7 -5.14 .14 27/27 1.3 1.1 -32.4 -5.34 .13 28/28 .4 5.4 -31.3 -5.43 .28

29/29 .8 12.0 -33.6 -5.73 .80

30/30 .55 3.4 72.76 -7.97 -29.7 -5.14 .86

31/31 3.1 51.3 3.81 8.78 -17.60 -1.54 <2.00

32/32 E.06 373 -28.90 -5.10 1.90

32/33 .41 113 -28.80 -5.11 .59

32/34 .26 281 -29.20 -5.16 .73

32/35 .20 1,120 -29.30 -5.15 .56

32/36 .34 332 -28.90 -5.12 .68
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Christenson, Hunt, and Parkhurst—Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004–06—SIR 2009–5036

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