New Mexico Geological Society Annual Spring Meeting — Abstracts

The Jornada del Huerto, located in southern New Mexico, is an intermontane syncIinal basin that is bounded by several north-south trending faults that define block ranges-mainly the Sierra Oscura and the San Andres Mountains to the east and the Fra Cristobal and the Caballo Mountains to the west. The north trending depression is approximately 120 miles in length and ranges from 10 to 30 miles in width. Quarternary and Tertiary sedimentary rocks of the santa Fe Group are covered by a thin veneer of alluvial sand and pediment gravel. The santa Fe Group is divided into four formations which are from base to top: 1) an unnamed transitional unit between the basin-fill surface and the santa Fe Group; 2) the Hayner Ranch Formation; 3) the Rincon Valley Formation; and 4) the Camp Rice Formation. Because of a variety of depositional environments, the Miocene to middle Pleistocene Santa Fe Group consists of two principal hydraulic units. The hydraulic units are composed of alluvial-fan and fluvial facies that are interbedded with a less permeable clay facies that retards the flow of water. Preliminary contour maps and piper trilinear diagrams of chemical (cations -Na⁺, K⁺, Ca⁺², Mg⁺², and anions -HCO₃-, CO₃^-2, CI^-, SO₄^-2) concentrations, pH, conductivity, and temperature data from 68 wells indicates that groundwater flow in the southern portion of the Jornada del Huerto is generally to the northwest, while flow in the northern end of the basin typically moves southwestward.