Major, trace and platinum-group element geochemistry of harzburgites and chromitites from Fuchuan, China, and its geological significance

Abstract

The Fuchuan peridotites have dual features of mid-ocean ridge basalt and supra-subducted zone peridotites and have been experienced high degrees of partial melting; chondrite-normalized “U”-shaped rare earth element (REE) patterns of Fuchuan harzburgites indicate that light REE enriched SSZ melts or fluids have participated in the interaction with peridotites; the Fuchuan chromitites are enriched in IPGE and depleted in PPGE, which are basically consistent with high-Al chromitites worldwide, and the low PGE concentrations of chromitites reflect a lack of sulfur saturation of the parental melts during an early stage of their crystallization; the Fuchuan peridotites and chromitites are believed to be formed in a back-arc spreading ridge between the Yangtze and Cathaysia blocks during 860–820 Ma.

Keywords

• platinum-group elements
• a back-arc spreading ridge
• podiform chromitites
• the fuchuan ophiolite
• the jiangnan orogen