SHRIMP U-Pb dating of detrital zircons from the Fenzishan Group in eastern Shandong, North China craton

An important exposure of Early Precambrian basement rocks in the North China craton is eastern Shandong, where the Paleoproterozoic Fenzishan and Jingshan groups are well preserved. Age histograms of detrital zircons from the Fenzishan and Jingshan groups can provide clues to understand the geological evolution of eastern Shandong. We report SHRIMP U-Pb zircon dating of a feldspar quartz schist from the Fenzishan Group. A total of 61 analyses were taken on 52 zircon grains and 36 analyses gave concordant ages (Discordance <10%). All the concordant zircons have high Th/U ratios and most show oscillatory zoning, indicating that they were derived from a magmatic source. They show age peaks at similar to 2.19Ga and similar to 2.48Ga, with two grains having Paleoarchean ages (>3.3Ga). Two youngest, concordant detrital zircons have Pb-207/Pb-206 ages of similar to 2.08Ga. Combined with early studies, some conclusions can be drawn as follows. 1) The formation age of the Fenzishan and Jingshan groups can be further limited in between 1.9 and 2. 1Ga; 2) the detrital zircon age histogram of the Fenzishan Group is distinct from that of the Jingshan Group, suggesting the differences of their source regions; 3) Paleoarchean crustal material may occur in eastern Shandong.