Lyell Collection
Journal of the Geological Society
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by WILLAN, R. C. R.
Right arrow Articles by SPIRO, B.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Journal of the Geological Society; 1996; v. 153; issue.1; p. 51-63;
DOI: 10.1144/gsjgs.153.1.0051
© 1996 Geological Society of London

Article

Sulphur sources for epithermal and mesothermal veins in Cretaceous–Tertiary magmatic-arc rocks, Livingston Island, South Shetland Islands

ROBERT C. R. WILLAN1 & BARUCH SPIRO2

1 British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
2 NERC Isotope Geosciences Laboratory, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, UK

Epithermal veins in early Triassic turbidites on Hurd Peninsula are isotopically homogeneous over an area of 13 km x 2 km (mean {delta}34S = +2.2{per thousand}, 1{sigma}= 1.7, n = 65) suggesting derivation from a deep circulating, neutral-chloride hydrothermal plume containing magmatic sulphur. The sense of fractionation (pyrite = +3.5, arsenopyrite = +3.2, sphalerite = +2.9, chalcopyrite = +2.5, galena = +0.9{per thousand}) and isotopic temperatures between 250 and 345°C suggest partial isotopic equilibration. Sulphides in massive dark carbonate/peperitic dyke breccias, with abundant magnetite, hematite and titanite and traces of barite, garnet, zircon and monazite are isotopically heavy (+7 to +14.9{per thousand}, n = 12) due either to dyke intrusion into the hydrothermal system resulting in degassing of H2S, or to a second, isotopically heavy and sulphate-bearing solution in fault zones along which dykes were subsequently intruded.

Vein sulphides in nearby Cretaceous volcanic rocks are similar to the epithermal system (mean = + 1.8{per thousand}, 1{sigma} = 0.9, n = 6, pyrite = +2.0, chalcopyrite = +1.5), suggesting sulphur-derivation by degassing of sub-volcanic magma, or remobilization of disseminated sulphides during plutonism. Sulphide in an Eocene tonalite pluton is slightly 32S-enriched (mean = 0{per thousand}, 1{sigma} = 1.9, n =7, molybdenite = +0.7, pyrite = +1.5, chalcopyrite = –2.6) and was exsolved directly from the cooling tonalitic magma.


Keywords: Andean Orogeny, South Shetland Islands, veins, sulphur, isotopes.




This article has been cited by other articles:


Home page
 Economic GeologyHome page
D. H. M. Alderton, D. H. M. Alderton, and A. E. Fallick
The Nature and Genesis of Gold-Silver-Tellurium Mineralization in the Metaliferi Mountains of Western Romania
Economic Geology, 2000; 95: 495 - 516.
[Abstract] [Full Text] [PDF]