U–Pb Dating and Trace Element Composition of Zircons from the Gujiao Ore-Bearing Intrusion, Shanxi, China: Implications for Timing and Mineralization of the Guojialiang Iron Skarn Deposit

The Gujiao ore field, located in the middle segment of the Luliang Mountain in central North China Craton (NCC), is one of iron skarn deposits of western iron belt in China. The U–Pb dating results of zircon by LA-ICP-MS suggest that the ore-related monzonite from the Guojialiang deposit was formed at 129.7 ± 1.7 Ma, early Cretaceous, which is consistent with the timing of iron skarn deposits in the Handan–Xingtai district of western iron belt. The zircons of monzonite present notable positive Ce anomalies (Ce/Ce* = 23.38–45.85), high Ce4+/Ce3+ values (154–385) and relatively high oxygen fugacity (fO2 = −13.09 to −15.36), and yield relatively low Ti-in-zircon temperatures. The physico-chemical conditions of the Guojialiang deposit were quite similar to these of ore-bearing plutons in the Handan-Xingtai district. The ore-bearing magmas are derived from the enriched lithospheric mantle with crustal material contribution, which played key role in oxidation state of the magma and the iron mineralization in the western iron belt.