Strontium isotope study of the VC-1 core hole and associated hydrothermal fluids and rocks from Valles caldera, Jemez Mountains, New Mexico

Journal Article · Fri Jun 10 04:00:00 EDT 1988 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB093iB06p06059· OSTI ID:6959276

Vuataz, F; Goff, F; Fouillac, C; Calvez, J

Chemical and strontium isotopic analyses have been performed on 10 geothermal waters from the Valles caldera/Jemez Mountain region, as well as 10 rock samples collected in the VC-1 scientific core hole. The /sup 87/Sr//sup 86/Sr values of other rocks sampled in the Jemez Mountains have also been used in this study to understand relations between the fluids and rocks of the volcanically driven geothermal system and the lateral outflow plume, discharging down the Jemez fault zone. The strontium content of ground-water is linked to the host rock composition, the aquifer temperature, and therefore the solubility of Sr-containing minerals. Low Sr concentrations in the fluid are found with a high temperature and/or volcanic host rocks, whereas high Sr concentrations are characteristic of a low temperature and/or a Paloezoic sedimentary aquifer. Important variations of the /sup 87/Sr//sup 86/Sr value in hydrothermal waters (0.70842--0.72193) are related to chemical composition, Sr content, and host rocks. For VC-1 core samples, the Sr isotopic ratios are also markedly variable (0.70459--0.75686), low for the Quaternary volcanics and high for the Paleozoic sedimentary rocks. The same observation is made for other Jemez Mountains rocks (0.70465--0.8163) with, in addition, high /sup 87/Sr//sup 86/Sr values for Precambrian crystalline rocks. A good correspondence is generally found between the waters and the reservoir rocks studied here, which indicates that isotopic equilibrium is rapidly attained. The following suite of hydraulically related fluids displays a progressive enrichment in radiogenic strontium: Baca wells (/sup 87/Sr--/sup 86/Sr = 0.7084--0.7094), VC-1 core hole at 483 m (0.7152--0.7154), Main Jemez Spring (0.7217), and Soda Dam (0.7219).

• Research Organization: Institut Mixte de Recherches Geexclamation; aothermiques, Bureau de Recherches Geologiques et Minieres, Orleans, France
• OSTI ID: 6959276
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 93:B6; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150201* -- Geology & Hydrology of Geothermal Systems-- USA-- (-1989)
AGE ESTIMATION
ALKALINE EARTH ISOTOPES
CALDERAS
CHEMICAL ANALYSIS
CHEMISTRY
ENERGY SYSTEMS
FEDERAL REGION VI
GEOCHEMISTRY
GEOLOGIC AGES
GEOTHERMAL SYSTEMS
GEOTHERMAL WELLS
HYDROTHERMAL SYSTEMS
IGNEOUS ROCKS
ISOTOPE DATING
ISOTOPES
JEMEZ MOUNTAINS
MOUNTAINS
NEW MEXICO
NORTH AMERICA
PALEOZOIC ERA
ROCKS
SAMPLING
STRONTIUM ISOTOPES
THERMAL WATERS
USA
VOLCANIC ROCKS
WELLS