Postdoctor XIAO Yan and her teacher ZHANG Hongfu research the effects of melt percolation on platinum group elements and Re-Os systematics of peridotites from the Tan-Lu fault zone.

Their data show that most of the Beiyan peridotites have flat chondrite-normalized PGE patterns whereas a considerable variation in total PGE abundances has been observed in lherzolites to highly fertile cpx-rich lherzolites and wehrlites.

The suprachondritic 187Os/188Os ratios in peridotites within the Tan-Lu fault zone relative to those away from it indicate that the Tan-Lu fault zone played an important role as a melt infiltrating channel in the radiogenic Os enrichment induced by melt percolation. This could be the reason for the Os isotopic heterogeneity observed in the eastern NCC. This study also confirms that Os isotopes and PGE appear to be mobile during massive melt percolation.

Fig. 1. Chondrite-normalized HFSE patterns of Beiyan lherzolites and wehrlites. (Image by XIAO)

Fig. 2. Histograms of Os abundance data for the eastern NCC peridotites compared with global xenoliths and massif peridotites from the literature. (Image by XIAO)

Xiao Y. and Zhang H.F. Effects of melt percolation on platinum group elements and Re-Os systematics of peridotites from the Tan-Lu fault zone, eastern North China Craton. Journal of the Geological Society,London. 2011, 168: 1201-1214 (Download Here)