Geochemistry of Salt-Spring and Shallow Subsurface Brines in the Rolling Plains of Texas and Southwestern Oklahoma

Abstract
Numerous salt-emission areas exist within the Permian outcrop in the Rolling Plains of Texas and southwestern Oklahoma. Sodium chloride waters underlie the area at relatively shallow depths, discharge from salt springs and salt seeps, and greatly impair the quality of ground and surface waters. This study distinguishes between brine derived from dissolution of halite by fresh, locally recharged ground water in a shallow ground-water system and brine derived from deep-basin brine aquifers. Halite dissolution brines typically have molar Na/Cl ratios of about 1, and Br/C and I/Cl weight ratios of less than 4 x 10-4 and less than 1 x 10-5, respectively. Deep-basin brines, in contrast, exhibit ratios of less than 1, greater than 2.5 x 10-3, and greater than 1 x 10-3, respectively.Three groups of brines in the Rolling Plains can be distinguished according to these ratios: (I) halite-dissolution brine, found in samples from most salt springs and test holes in the north and west; (2) brine from deep-basin aquifers, evident in the shallow subsurface (30 to 100 ft or 9 to 30 m) in the south; and (3) brine exhibiting characteristics of both halite-dissolution and deep-basin brines, suggesting mixing. Other chemical constituents (Ca, Mg, and K) support this grouping of the brine data as well as our interpretation of different brine origins.The isotopic composition (δ18O and δD) of the salt springs indicates a local meteoric origin for the halite-dissolution brines. Some brine samples from the shallow subsurface in the southeast plot on a line that includes deep-basin brine values and meteoric-water values as end points, suggesting dilution of deep-basin brine by meteoric ground water. The presence of deep-basin brine near land surface in the study area was not recognized in previous studies.
Authors
Bernd C. Richter
Charles W. Kreitler
Citation

Richter, B. C., and Kreitler, C. W., 1986, Geochemistry of Salt-Spring and Shallow Subsurface Brines in the Rolling Plains of Texas and Southwestern Oklahoma: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 155, 47 p.

Code
RI155
ISSN
2475-367X
Number
155
Number of figures
25
Number of pages
47
Publisher
The University of Texas at Austin, Bureau of Economic Geology
Series
Report of Investigation
Year
1986