Abstract
Sulphur isotopes have become a widely deployed tool to address the sources of fluids in ore systems, given the widespread interaction of H2S, HS− and S2 - with metals. However, the sensitivity of sulphur isotopes to magma source composition relative to other radiogenic isotopes and the nature of processes differentially affecting isotopic systems have not been extensively explored in magmatic mineral systems. In this work we present a case study of sulphide bearing magmas within the Fraser Zone of the Albany-Fraser Orogen in Western Australia that seeks to evaluate the sensitivity of sulphur isotopes to track magma source composition in space and time. New δ34S data from mineralised NRM, Plato and Octagonal localities of the Fraser Zone indicate variable degrees of assimilation of local sediments of the Snowys Dam Formation. Despite an Archean heritage in the Fraser Zone magmas being indicated by radiogenic isotopes, sparse xenocrystic zircon, and whole rock geochemical modelling, Δ33S data from these localities reveal Archean sulphur is absent; implying decoupling of the sulphur component from other geochemical and isotopic systems. This is consistent with a mechanism by which Archean sulphur was removed from detrital material incorporated in the Fraser Zone. We conclude that sulphides were stripped from sediments during uplift, erosion and transport to the Fraser Zone, with these Archean-sulphur depleted sediments then assimilated by the Fraser Zone parental magmas. Our results indicate a coupling between variable assimilation of external sulphur by Fraser Zone magmas and the mineralisation present at the prospects studied. However assimilated sulphur cannot account for all of the sulphur within mineralised samples, indicating the involvement of additional processes such as tenor upgrading.
| Original language | English |
|---|---|
| Article number | 105379 |
| Journal | Precambrian Research |
| Volume | 332 |
| DOIs | |
| Publication status | Published - 15 Sep 2019 |
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Tracking mineralisation with in situ multiple sulphur isotopes : a case study from the Fraser Zone, Western Australia. / Walker, A. T.; Evans, K. A.; Kirkland, C. L.; Martin, L.; Kiddie, O. C.; Spaggiari, C. V.
In: Precambrian Research, Vol. 332, 105379, 15.09.2019.Research output: Contribution to journal › Article
TY - JOUR
T1 - Tracking mineralisation with in situ multiple sulphur isotopes
T2 - a case study from the Fraser Zone, Western Australia
AU - Walker, A. T.
AU - Evans, K. A.
AU - Kirkland, C. L.
AU - Martin, L.
AU - Kiddie, O. C.
AU - Spaggiari, C. V.
PY - 2019/9/15
Y1 - 2019/9/15
N2 - Sulphur isotopes have become a widely deployed tool to address the sources of fluids in ore systems, given the widespread interaction of H2S, HS− and S2 - with metals. However, the sensitivity of sulphur isotopes to magma source composition relative to other radiogenic isotopes and the nature of processes differentially affecting isotopic systems have not been extensively explored in magmatic mineral systems. In this work we present a case study of sulphide bearing magmas within the Fraser Zone of the Albany-Fraser Orogen in Western Australia that seeks to evaluate the sensitivity of sulphur isotopes to track magma source composition in space and time. New δ34S data from mineralised NRM, Plato and Octagonal localities of the Fraser Zone indicate variable degrees of assimilation of local sediments of the Snowys Dam Formation. Despite an Archean heritage in the Fraser Zone magmas being indicated by radiogenic isotopes, sparse xenocrystic zircon, and whole rock geochemical modelling, Δ33S data from these localities reveal Archean sulphur is absent; implying decoupling of the sulphur component from other geochemical and isotopic systems. This is consistent with a mechanism by which Archean sulphur was removed from detrital material incorporated in the Fraser Zone. We conclude that sulphides were stripped from sediments during uplift, erosion and transport to the Fraser Zone, with these Archean-sulphur depleted sediments then assimilated by the Fraser Zone parental magmas. Our results indicate a coupling between variable assimilation of external sulphur by Fraser Zone magmas and the mineralisation present at the prospects studied. However assimilated sulphur cannot account for all of the sulphur within mineralised samples, indicating the involvement of additional processes such as tenor upgrading.
AB - Sulphur isotopes have become a widely deployed tool to address the sources of fluids in ore systems, given the widespread interaction of H2S, HS− and S2 - with metals. However, the sensitivity of sulphur isotopes to magma source composition relative to other radiogenic isotopes and the nature of processes differentially affecting isotopic systems have not been extensively explored in magmatic mineral systems. In this work we present a case study of sulphide bearing magmas within the Fraser Zone of the Albany-Fraser Orogen in Western Australia that seeks to evaluate the sensitivity of sulphur isotopes to track magma source composition in space and time. New δ34S data from mineralised NRM, Plato and Octagonal localities of the Fraser Zone indicate variable degrees of assimilation of local sediments of the Snowys Dam Formation. Despite an Archean heritage in the Fraser Zone magmas being indicated by radiogenic isotopes, sparse xenocrystic zircon, and whole rock geochemical modelling, Δ33S data from these localities reveal Archean sulphur is absent; implying decoupling of the sulphur component from other geochemical and isotopic systems. This is consistent with a mechanism by which Archean sulphur was removed from detrital material incorporated in the Fraser Zone. We conclude that sulphides were stripped from sediments during uplift, erosion and transport to the Fraser Zone, with these Archean-sulphur depleted sediments then assimilated by the Fraser Zone parental magmas. Our results indicate a coupling between variable assimilation of external sulphur by Fraser Zone magmas and the mineralisation present at the prospects studied. However assimilated sulphur cannot account for all of the sulphur within mineralised samples, indicating the involvement of additional processes such as tenor upgrading.
KW - Fraser Zone
KW - Magmatic sulphides
KW - Multiple sulphur isotopes
KW - Sulphide minerals
KW - Western Australia
UR - http://www.scopus.com/inward/record.url?scp=85068527608&partnerID=8YFLogxK
U2 - 10.1016/j.precamres.2019.105379
DO - 10.1016/j.precamres.2019.105379
M3 - Article
VL - 332
JO - Precambrian Research
JF - Precambrian Research
SN - 0301-9268
M1 - 105379
ER -