Petrology，Geochemistry and Constraint for the Geodynamic Process of Ore-bearing Diorites in Ta' Ershan-Erfengshan, Shanxi

The Ta'ershan-Erfengshan iron skarn deposit, is located in the south Taihang mountains, central North China Craton(NCC). The diorites that hosted Ta'ershan-Erfengshan deposits, namely Ta'ershan and Erfengshan intrusions, yielded zircon U-Pb ages of(128.7±3.0)Ma~(131.2±2.2)Ma, which are in accordance with other Fe-skarn-related intrusions in eastern NCC, suggesting that they were related to same tectonic events. The geochemical data of ore-bearing diorites indicate that Ta'ershan diorite belongs to calc-alkalic aluminum diorite and Erfengshan diorite belongs to alkaline aluminum diorite. The Harker diagram and Rb/Nd-Rb diagram of the Ta'ershan-Erfengshan diorites indicate they are derived from one common source by different degrees of partial melting. At the same time, they also have similar geochemical characteristics, such as low contents of SiO₂(57.17%～65.51%), high contents of alkaline(Na₂O = 5.07%~6.72%，K₂O= 7.92%~11.73%), low Mg^# values, enriched in LILEs(Sr、Ba) and LREEs and depleted in HFSEs(Ni、Ta、Ti). In comparison with the chronology and geochemistry data of Pingshun-Xi'anli、Anlin and Laiwu diorites, this paper suggests that the central part of the North China Craton has not undergone delamination similar to the eastern part, and that the melting magma of the ancient lower crust has played an important role in the formation of iron skarn deposits.