PGE geochemistry of sulfide-bearing rocks from the Suoi Cun intrusion,Cao Bang province,Northeastern Vietnam

摘要

The Late Permian (262-266 Ma) lherzolite-gabbronorite-dolerite Suoi Cun intrusion is located within the Song Hien rift zone (Northeastern Vietnam).The intrusion consists of two rock associations-gabbrodolerite-congadiabase and lherzolite-gabbronorite associations of the Cao Bang complex.The PGE-Cu-Ni sulfide mineralization of the Suoi Cun intrusion is hosted by plagiolherzolite,picrite and olivine melanogabbro of the lherzolite-gabbronorite association.Features of the distribution of Ni,Cu and PGE in 100％ sulfide of the peridotite from the Suoi Cun intrusion of the lherzolite-gabbronorite association indicate that the sulfide liquid was enriched in Ni,Cu and PGE as the result of multiple interactions with new portions of silicate melt.Low Cu/Pd ratios and the configuration of chondrite-normalized chalcophile element patterns in sulfide-bearing rocks suggest that the sulfide liquid was segregated in the intermediate chamber from the primary PGE undepleted picrobasaltic magma.This magma was not experience the earlier sulfide segregation.Our study allowed to justify the volcanic-plutonic origin of the Suoi Cun intrusion.Since the parental magma of the Suoi Cun intrusion has the potential to produce PGE as a by-product,there is a potential to find economic PGE-Cu-Ni mineralization in numerous intrusions of the Cao Bang complex in the Northeastern Vietnam.