Formation of Ni?Cu?Platinum Group Element sulfide mineralization in the Sudbury Impact Melt Sheet

2004 ◽  
Vol 82 (3-4) ◽  
pp. 217-258 ◽  
Author(s):  
R. R. Keays ◽  
P. C. Lightfoot
Keyword(s):  
Platinum Group Element ◽  
Group Element ◽  
Sulfide Mineralization ◽  
Impact Melt ◽  
Platinum Group

Multiple S Isotopes and S Isotope Heterogeneity at the East Eagle Ni-Cu-Platinum Group Element Deposit, Northern Michigan

2020 ◽  
Vol 115 (3) ◽  
pp. 527-541
Author(s):  
E.K. Benson ◽  
E.M. Ripley ◽  
C. Li ◽  
B.W. Underwood ◽  
R. Mahin
Keyword(s):  
Platinum Group Element ◽  
Group Element ◽  
Spatial Proximity ◽  
Small Scale ◽  
Sulfide Mineralization ◽  
Exchange Reactions ◽  
Wide Range ◽  
Platinum Group ◽  
Northern Michigan ◽  
S Isotope

Abstract The East Eagle Ni-Cu-platinum group element deposit is a conduit-type deposit located in northern Michigan, in close spatial proximity to the currently producing Eagle deposit. Massive and semimassive (net-textured) sulfide mineralization at East Eagle occurs approximately 800 m lower in the stratigraphic sequence than that at Eagle and only ~200 m above the contact between Proterozoic and Archean rocks. Although sulfide mineralogy and textural types are similar at the two occurrences, there are important differences in their S isotope systematics. Massive sulfide mineralization at East Eagle is characterized by a relatively narrow range of δ34S values from 1.5 to 3.2‰. Semimassive sulfides show a similar range from 2.1 to 3.8‰. In strong contrast to these values, those from disseminated sulfides that border the massive and semimassive mineralization define a much larger range from –4.3 to 22.8‰. The much more restricted range in δ34S values recorded in the massive and semimassive sulfide mineralization compared to that of the disseminated mineralization is thought to reflect isotopic exchange reactions in the conduit involving accumulated sulfide and pulses of magma containing S of mantle origin. The ∆33S values of all three major types of sulfide mineralization at East Eagle are near 0‰, with most values between –0.03 and 0.03‰. Unlike ∆33S values from semimassive sulfide mineralization at Eagle, the ∆33S values at East Eagle show no, or very limited, evidence for the involvement of S derived from Archean sedimentary rocks. The wide range in δ34S values recorded in the disseminated mineralization provides strong evidence that S from Proterozoic sedimentary host rocks was involved in the mineralization; in some cases, as much as 85% of the S may have been of external origin. In addition to the wide range in δ34S values, the disseminated mineralization is characterized by spatially heterogeneous δ34S values. Meter-scale S isotope variations, as well as variations in Pt and Pd tenor, are consistent with multiple inputs of magma, each characterized by distinct S isotope ratios. Heterogeneity of several per mill at the centimeter scale indicates that the degree of supercooling exceeded the S diffusivity, preserving small-scale S isotope variability inherited from the sedimentary country-rock source. Elongate, branching plagioclase grains in many of the gabbroic rocks that host the disseminated sulfide mineralization are consistent with a rapid second stage of cooling.

PLATINUM GROUP ELEMENT (PGE) SYSTEMATICS OF ARC SULFIDES: A CASE STUDY FROM CUMULATES OF THE CHILAS COMPLEX, KOHISTAN ARC, PAKISTAN

2016 ◽  
Author(s):  
Ijaz Ahmad ◽  
◽  
Jeremy P. Richards ◽  
Jingao Liu ◽  
D. Graham Pearson ◽  
...  
Keyword(s):  
Platinum Group Element ◽  
Group Element ◽  
Platinum Group

scholarly journals The komatiite-mantle platinum-group element paradox

2021 ◽  
Author(s):  
Pedro Waterton ◽  
James Mungall ◽  
D. Graham Pearson
Keyword(s):  
Platinum Group Element ◽  
Group Element ◽  
Platinum Group
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