|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
U. S. Geol. Surv., Denver, CO, United States
Alunite deposits formed 23 m.y. ago in near-surface, highly oxidizing conditions at the tops of hydrothermal plumes that were spaced at 3- to 4-km intervals around a monzonite stock. The delta 34 S values of 11.5 to 15.4 per mil for replacement alunite along with geologic constraints indicate that sulfate sulfur was derived from underlying Mesozoic evaporites. The delta 34 S values of -15.3 to +5.1 per mil of underlying pyrite, however, indicate that reduced sulfur, necessary to produce low pH during oxidation, either was produced by partial reduction of the evaporite sulfate or came from another source. Vein-type alunite deposits formed 14 m.y. ago as open-space fillings in extension fractures above a concealed stock. Crystals of alunite grew inward from the walls, forming veins of nearly pure alunite as much as 20 m thick. The delta 34 S values near zero per mil indicate that the vein-type alunite sulfur probably had a magmatic source, and it appears that the sulfur may have been present as SO 2 shortly after degassing from the magma. The probable magmatic origin for sulfur in the 14-m.y.-old vein-type alunite and its deposition from vapor-rich fluids, as well as the probable magmatic origin for sulfur in the surrounding base and precious metal deposits, suggest that the underlying stock may host porphyry-type deposits.--Modified journal abstract.
This record provided courtesy of AGI/GeoRef.
This article has been cited by other articles:
|
|
 |
|
  J. A. MARTINEZ, C. J. DE CISNEROS, and E. CABALLERO Natural acid sulphate alteration in bentonites (Cabo de Gata, Almeria, SE Spain) Clay Minerals, March 1, 2007; 42(1): 89 - 107. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. W. Rockwell, C. G. Cunningham, G. N. Breit, and R. O. Rye Spectroscopic Mapping of the White Horse Alunite Deposit, Marysvale Volcanic Field, Utah: Evidence of a Magmatic Component Economic Geology, November 1, 2006; 101(7): 1377 - 1395. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Simeone, J. H. Dilles, G. Padalino, and M. Palomba Mineralogical and Stable Isotope Studies of Kaolin Deposits: Shallow Epithermal Systems of Western Sardinia, Italy Economic Geology, January 1, 2005; 100(1): 115 - 130. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. L. Deyell, R. Leonardson, R. O. Rye, J. F. H. Thompson, T. Bissig, and D. R. Cooke Alunite in the Pascua-Lama High-Sulfidation Deposit: Constraints on Alteration and Ore Deposition Using Stable Isotope Geochemistry Economic Geology, January 1, 2005; 100(1): 131 - 148. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. A. Rodgers, K. A. Hamlin, P. R. L. Browne, K. A. Campbell, and R. Martin The steam condensate alteration mineralogy of Ruatapu cave, Orakei Korako geothermal field, Taupo Volcanic Zone, New Zealand Mineralogical Magazine, February 1, 2000; 64(1): 125 - 142. [Abstract] [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
