88 / 2015-11-09 19:09:18

HFSE Features of Meta-basaltic Wall-rocks of BIFs in Benxi Area, Liaoning Province, China

HFSE,BIFs,meta-basaltic wall-rocks,Benxi area,intra-continental back-arc basin

Banded iron formations (BIFs) have the close spatial and temporal association with their meta-basaltic wall-rocks in Benxi area, Liaoning province, China. Through the analysis on the high field strength elements (HFSEs) of the meta-basaltic wall-rocks of BIFs, we firstly find that their Nb/Ta ratios (7.00~19.93) were distinctly fractionated but fractionation of Zr/Hf ratios (33.46~38.28) is not so obvious. In addition, the fractionation of Nb/Ta ratios has the regional tendency of increasing gradually from Gongchanling to Nanfen and Waitoushan. These migrations and fractionations of HFSEs reflect basin evolution along with the subduction process. Their (Nb/Yb)N ratios (1.21~18.45, average 2.72) are bigger than 1, further suggesting that tectonic setting for BIFs formation in study area is the intra-continental back arc basin associated with subduction process.