TY - JOUR
T1 - Gold in the mantle
T2 - The role of pyroxenites
AU - Saunders, J. Edward
AU - Pearson, Norman J.
AU - O'Reilly, Suzanne Y.
AU - Griffin, William L.
PY - 2016/2/1
Y1 - 2016/2/1
N2 - Mantle pyroxenites are the crystallised products of mafic silicate melts, which are commonly invoked as metasomatic agents in the upper mantle. This study has analysed the trace elements of sulfides, with a specific focus on gold, hosted in a suite of mantle pyroxenite xenoliths from Qilin in the Cathaysia Block, southeast China. These are compared with sulfides hosted in peridotite xenoliths from the same locality to assess the difference in the abundances of Au, and a suite of siderophile and chalcophile elements between the sulfides hosted in mobile melts in the upper mantle and their host "wall" rocks.Both the peridotite- and pyroxenite-hosted sulfides show a wide spectrum of trace element contents. The pyroxenite-hosted sulfides typically have PGE and Au concentrations that are an order of magnitude or more below those measured in the peridotite-hosted sulfides (lherzolite-hosted sulfides: total PGE. = 95 ± 118 ppm, Au. = 1.4 ± 2.6 ppm; pyroxenite-hosted sulfides: total PGE. = 0.25 ± 0.70 ppm, Au. = 0.14 ± 0.39 ppm). Furthermore, the Ir group PGE (Ir, Os and Ru) are present in lower concentrations than the Pd-group PGE (Pd, Pt and Rh). This may lead to a distinct signature if the melts from which these sulfides crystallise interact with lherzolitic sulfides. The overall low abundances of these elements within the pyroxenites suggests that the parent melts are an inefficient medium for enriching any of these elements in the upper mantle.
AB - Mantle pyroxenites are the crystallised products of mafic silicate melts, which are commonly invoked as metasomatic agents in the upper mantle. This study has analysed the trace elements of sulfides, with a specific focus on gold, hosted in a suite of mantle pyroxenite xenoliths from Qilin in the Cathaysia Block, southeast China. These are compared with sulfides hosted in peridotite xenoliths from the same locality to assess the difference in the abundances of Au, and a suite of siderophile and chalcophile elements between the sulfides hosted in mobile melts in the upper mantle and their host "wall" rocks.Both the peridotite- and pyroxenite-hosted sulfides show a wide spectrum of trace element contents. The pyroxenite-hosted sulfides typically have PGE and Au concentrations that are an order of magnitude or more below those measured in the peridotite-hosted sulfides (lherzolite-hosted sulfides: total PGE. = 95 ± 118 ppm, Au. = 1.4 ± 2.6 ppm; pyroxenite-hosted sulfides: total PGE. = 0.25 ± 0.70 ppm, Au. = 0.14 ± 0.39 ppm). Furthermore, the Ir group PGE (Ir, Os and Ru) are present in lower concentrations than the Pd-group PGE (Pd, Pt and Rh). This may lead to a distinct signature if the melts from which these sulfides crystallise interact with lherzolitic sulfides. The overall low abundances of these elements within the pyroxenites suggests that the parent melts are an inefficient medium for enriching any of these elements in the upper mantle.
KW - PGE fractionation
KW - Mantle melting
KW - Chalcophile elements
KW - Metasomatised mantle
KW - Base metal sulfides
KW - LA-ICP-MS
UR - http://www.scopus.com/inward/record.url?scp=84953924041&partnerID=8YFLogxK
U2 - 10.1016/j.lithos.2015.12.008
DO - 10.1016/j.lithos.2015.12.008
M3 - Article
AN - SCOPUS:84953924041
SN - 0024-4937
VL - 244
SP - 205
EP - 217
JO - Lithos
JF - Lithos
ER -