Stable isotope investigations of an active geothermal system in Valles Caldera, Jemez Mountains, New Mexico
- Creators
- Lambert, Steven J.
- Epstein, Samuel
Abstract
^(16)O/^(16)O, ^(13)C/^(12)C and D/H measurements have been made on rocks and minerals from drill cuttings (0 to 1700 m depth) from Valles Caldera, New Mexico, a post-Pliocene collapsed volcano containing an active hydrothermal system. δ^(18)O values of calcite reflect isotopic equilibrium with large amounts of a meteoric-hydrothermal fluid δ^(18)O = - 12‰ at temperatures between 60 and 280°C. Calcites appear to have retained their original ^(13)C/^(12)C ratios, typical of either marine or fresh-water origin. The mineralogical changes which have accompanied the hydrothermal activity resulted in decreases in whole-rock δ^(18)O values of as much as 7%0 as compared to the original δ^(18)O of the volcanically-derived rocks. The isotopic composition of hydrothermal quartz in altered rocks is entirely unrelated to the most recent episode of alteration. D/H ratios of kaolinite formed in equilibrium with the meteoric-hydrothermal fluid have allowed the determination of approximate kaolinite-water hydrogen isotope fractionation factors between 60 and 280°C. These data are compatible with previous determinations at 400 and 300°C. The In α^D (kao-H,O) relationship with 1/T^2 is not linear over the temperature range 400 to 25°C.
Additional Information
© 1980 Elsevier Scientific Publishing Company. Received September 6, 1977; revised and accepted September 14, 1979. We wish to thank Carel Otte and Richard Dondanville of the Union Oil Company of California for graciously providing samples from borehole cuttings and surface outcrops for this study. In addition, we acknowledge the assistance of Joop Goris, Jane Young, and the late Curtis Bauman, who provided technical support and advice. We benefited from stimulating discussions with M.J. DeNiro, Y. Kolodny, T.R. McGetchin, S.M. Savin, C.J. Yapp and H.W. Yeh. This research was supported by a grant from the National Science Foundation, grant No. EAR78-16873. During the course of this work, one of us was supported by an N.S.F. Graduate Fellowship, an N.S.F. Energy-Related Traineeship, and an N.S.F. Energy-Related Postdoctoral Fellowship.Additional details
- Eprint ID
- 42447
- DOI
- 10.1016/0377-0273(80)90010-4
- Resolver ID
- CaltechAUTHORS:20131114-092258813
- EAR78-16873
- NSF
- NSF Graduate Fellowship
- NSF Energy-Related Traineeship
- NSF Energy-Related Postdoctoral Fellowship
- Created
-
2013-11-14Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Other Numbering System Name
- Caltech Division of Geological and Planetary Sciences
- Other Numbering System Identifier
- 2783