Some petrologic and oxygen isotopic relationships in the amulet mine, noranda, quebec, and their bearing on the origin of archean massive sulfide deposits
Journal Article
·
· Econ. Geol.; (United States)
A concentrically zoned alteration pipe is present at the Amulet ''A'' Cu-Zn mine in the Archean Abitibi greenstone belt. The pipe consists of a central core zone of so-called ''dalmatianite'' surrounded by a zone of biotite-bearing grid-fracture alteration. Study of the dalmatianite indicates that these rocks experienced two episodes of recrystallization. Whole-rock /delta//sup 18/O values decrease from about 6 to 10 in most of the Abitibi belt to 5 to 7 in the country rocks surrounding the ore deposit, to values as low as 3.6 in the core of the dalmatianite zone. This oxygen isotopic zoning must have been produced by the hydrothermal activity, because the dehydration reactions associated with contact metamorphism cannot have affected /delta//sup 18/O by more than 0.5 per mil. Assuming an alteration temperature of 300/degree/sub p/lus or minus/50/degree/C and a water/rock ratio greater than two, the hydrothermal fluid must have had /delta//sup 18/O .0.5/plus or minus/1.0. This indicates that the Amulet ore deposit formed from a hydrothermal fluid that had a /delta//sup 18/O value similar both to modern seawater and to the fluids which formed the Phanerozoic massive sulfide deposits of the Kuroko and Cyprus types. 51 refs.
- Research Organization:
- Calif Inst of Technol, Pasadena, USA
- OSTI ID:
- 6940293
- Journal Information:
- Econ. Geol.; (United States), Journal Name: Econ. Geol.; (United States) Vol. 77:1; ISSN ECGLA
- Country of Publication:
- United States
- Language:
- English
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