Chowdhury, Ali H.¹, Cindy Ridgeway¹, Robert E. Mace¹
(1) Texas Water Development Board, Austin, TX

ABSTRACT: Source Areas of the San Solomon Spring System, West Texas: Chemical and Isotopic Evidence

The San Solomon Spring system includes Phantom Lake, Giffin, Saragosa, San Solomon, West Sandia and East Sandia springs. They are located along the valley floor between the Davis Mountains and the Toyah basin. These springs historically provided a considerable amount of irrigation water for this semi-arid area. Two rare endangered species, the Comanche spring pupfish and the Pecos gambusia, are also endemic to these springs.
Two sources of waters were identified for the springs – one derived from the Davis Mountains and the other from west of the Apache and the Delaware Mountains. Discharge from the Davis Mountains fails to reach the springs except during intense local rainfall events. Groundwater from the Davis Mountains is dominated by Ca-Na-HCO₃ facies. The spring waters and the groundwater west of the Apache and the Delaware Mountains are dominated by Na-Cl-SO₄ facies. Groundwater composition and ³⁴S values from west of the Apache and the Delaware Mountains indicate their derivation from dissolution of halite and gypsum. Groundwater from the Davis Mountains is fresh containing low total dissolved solids. Groundwater from the Davis Mountains has high ³H, ¹⁴C pmC, and lighter ¹³C values suggesting contribution from modern to sub-modern waters. Most of the spring waters and groundwater from west of the Apache and the Delaware Mountains have low ³H, low ¹⁴C pmC and heavier ¹³C values suggesting their derivation from an older groundwater system. NETPATH simulations suggest that a substantial amount of the spring waters could be derived from west of the Apache and the Delaware Mountains.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.