Chalcophile and platinum-group element (PGE) concentrations in the sulfide minerals from the McCreedy East deposit,Sudbury, Canada,and the origin of PGE in pyrite |
| |
| Authors: | Sarah A S Dare Sarah-Jane Barnes Hazel M Prichard Peter C Fisher |
| |
| Institution: | 1.Sciences de la Terre,Université du Québec à Chicoutimi,Saguenay,Canada;2.School of Earth and Ocean Sciences,Cardiff University,Cardiff,UK |
| |
| Abstract: | Magmatic sulfide deposits consist of pyrrhotite, pentlandite, chalcopyrite (± pyrite), and platinum-group minerals (PGM).
Understanding the distribution of the chalcophile and platinum-group element (PGE) concentrations among the base metal sulfide
phases and PGM is important both for the petrogenetic models of the ores and for the efficient extraction of the PGE. Typically,
pyrrhotite and pentlandite host much of the PGE, except Pt which forms Pt minerals. Chalcopyrite does not host PGE and the
role of pyrite has not been closely investigated. The Ni–Cu–PGE ores from the South Range of Sudbury are unusual in that sulfarsenide
PGM, rather than pyrrhotite and pentlandite, are the main carrier of PGE, probably as the result of arsenic contribution to
the sulfide liquid by the As-bearing metasedimentary footwall rocks. In comparison, the North Range deposits of Sudbury, such
as the McCreedy East deposit, have As-poor granites in the footwall, and the ores commonly contain pyrite. Our results show
that in the pyrrhotite-rich ores of the McCreedy East deposit Os, Ir, Ru, Rh (IPGE), and Re are concentrated in pyrrhotite,
pentlandite, and surprisingly in pyrite. This indicates that sulfarsenides, which are not present in the ores, were not important
in concentrating PGE in the North Range of Sudbury. Palladium is present in pentlandite and, together with Pt, form PGM such
as (PtPd)(TeBi)2. Platinum is also found in pyrite. Two generations of pyrite are present. One pyrite is primary and locally exsolved from
monosulfide solid solution (MSS) in small amounts (<2 wt.%) together with pyrrhotite and pentlandite. This pyrite is unexpectedly
enriched in IPGE, As (± Pt) and the concentrations of these elements are oscillatory zoned. The other pyrite is secondary
and formed by alteration of the MSS cumulates by late magmatic/hydrothermal fluids. This pyrite is unzoned and has inherited
the low concentrations of IPGE and Re from the pyrrhotite and pentlandite that it has replaced. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
