Partition of Platinum-Group Elements between arsenide and sulfide minerals in magmatic Ni-Cu sulfide systems
The partition coefficients of platinum-group elements (PGE) between arsenide and sulfide minerals (DPGEAs/sulf) have been calculated by determining in situ concentrations of these elements by LA-ICP-MS in coexisting arsenide (maucherite) and sulfide (pyrrhotite,pentlandite and chalcopyrite) minerals from the Beni Bousera Cr-Ni mineralization (North Morocco).Maucherite contains significant amounts of all PGE (average values,8.3 ppm Os,25.8 ppm Ir,7.5 ppm Ru,8.6 ppm Rh,61.7 ppm Pd and 7.5 ppm Pt),whereas sulfides have contents commonly below 0.2 ppm.With the exception of Pt,mass balance calculation indicates that arsenides and sulfides account for the bulk of PGE in the samples.The calculated DPGEAs/sulf reveal the strong affinity of PGE by arsenide minerals: DIrAs/sulf = 923,DRhAs/sulf = 540,DPtAs/sulf = 325,DPdAs/sulf = 254,DOsAs/sulf = 145 and DRuAs/sulf = 50.The maucherite grains,which occur included within the sulfides (mostly pyrrhotite),can attribute to: 1) direct crystallization from sulfide melt before mss crystallization,or 2) crystallization from an arsenide melt segregated by immiscibility from a sulfide melt.Because of maucherite melts incongruently above 830oC,well below the temperature of crystallization of mss (around 1000oC),maucherite probably represents the crystallization product of droplets of arsenide melt and the calculated partition coefficients,the partition values of PGE between arsenide and sulfide melts.
R.Pi(n)a F.Gervilla S.-J.Barnes L.Ortega R.Lunar
Facultad de Geología,Universidad Complutense de Madrid,Spain Dpto.Mineralogía and IACT(Universidad de Granada-CSIC)Granada,Spain Sciences de la Terre,Université du Québec à Chicoutimi,QC G7H 2B1,Canada
国际会议
贵阳
英文
18-21
2012-06-16（万方平台首次上网日期，不代表论文的发表时间）