fiwF- tyOS&»l& ISOTOPIC TRACERS OF GOLD DEPOSITION IN PALEOZOIC LIMESTONES/

Strontium isotopic analyses of barren and mineralized Paleozoic carbonate rocks show that hydrothermal fluids added radiogenic strontium ("Sr) to the mineralized zones. At Bare Mountain, samples collected from mineralized areas have fi^Sr, values (per mil deviation from primary marine values) ranging from +3.0 to +23.0 (mean of this log-normal distribution is +7.0), whereas unmineralized carbonate rocks have S^Sr, values of-0.6 to +2.9 (mean of +1.07 ±1.03). In other ranges (Striped Hills, Spring Mountains, and ranges in the vicinity of Indian Springs Valley), S^Sr, values of the unmineralized carbonate rocks are even lower and virtually indistinguishable from primary marine values. This correlation of elevated S^Sr, values with mineralized zones provides a useful technique for assessing the mineral potential of the Paleozoic basement beneath Yucca Mountain, and may find broader use in mineral exploration in the Basin and Range province as a whole