Strontium isotope characterization of the Ash Meadows ground-water system, southern Nevada, USA

Abstract

The regional {delta}{sup 87}Sr variation in ground water of the Ash Meadows flow system is consistent with previous work which identifies the Spring Mountains as a major recharge area. {delta}{sup 87}Sr values between -1.06 and 0.79 in water from high springs are indistinguishable from the {delta}{sup 87}Sr values of the Paleozoic carbonate rocks which compose most of the Spring Mountains. The bulk of the discharge at Ash Meadows carries strontium with {delta}{sup 87}Sr values between 4.43 and 4.99. These discharge values require recharge to the system with {delta}{sup 87}Sr values substantially greater than 5. Such waters are identified in the west-central part of the flow system, reflecting a northerly source, and in one spring form the Pahranagat Valley at the northeastern limit of the system. The ultimate source of these large {delta}{sup 87}Sr values may include Tertiary felsic tuffs, Upper Devonian and Mississippian Eleana Formation, or Precambrian clastic rocks. 14 refs., 3 figs.