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Title: Fossil meteoric groundwaters in the Delaware Basin of southeastern New Mexico

Technical Report ·
OSTI ID:7117490

{sup 18}0/{sub 16}0 and D/H ratio measurements have been made on groundwaters sampled from the Rustler Formation (Ochoan, Permian) and related rocks in the northern Delaware Basin of southeastern New Mexico. Most confined Rustler waters at the WIPP site and to the west in Nash Draw and confined waters, from the Capitan Limestone constitute one population in {delta}D/{delta}{sup 18}O space, while unconfined groundwaters inferred to originate as modern surface recharge waters. A likely explanation for this distinction is that meteoric recharge to most of the Rustler and Capitan units took place in the geologic past under climatic conditions significantly different from those of the present. Available tritium and radiocarbon data are consistent with this hypothesis, and the apparent age of confined groundwaters is in excess of 12,000 radiocarbon years, suggesting that recharge took place under wetter conditions in the late Pleistocene. Water at the Rustler/Salado contact a t the WIPP site is of meteoric origin but has experienced isotopic alteration that increases with decreasing permeability. Rustler dolomites have not recrystallized in isotopic equilibrium with Rustler Formation water. The absence of modern meteoric recharge to the Rustler Formation at and near the WIPP site indicates that the hydrologic system there is not at steady state. Instead, the system is responding to the cessation of local recharge, this cessation occurring more than 10,000 years ago.

Research Organization:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Organization:
USDOE; USDOE, Washington, DC (United States)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
7117490
Report Number(s):
SAND-89-2660; ON: DE92017361
Country of Publication:
United States
Language:
English