Age, geochemistry and petrogenesis of Huashan granitonid pluton on the southern margin of the North China Block

The Huashan granitoid pluton is located on the southern margin of the North China Block. Zircon LA-ICP-MS dating of the porphyritic monzogranites from the Huashan pluton yielded an age of 128±1Ma. This pluton and its neighboring Wuzhangshan pluton are of high K calc-alkaline series and belong to metaluminous to weak peraluminous rocks. They are enriched in large ion lithophile elements (LREE, Rb, Ba, K, Sr) and depleted in high-field strength elements (HREE, Zr, Hf, Ta, Nb, P, Ti), with insignificant Eu anomaly. These characteristics suggest that the granitoids have I-A type granite features. The zircon εHf(t) values and tDM2 values of the Huashan porphyritic monzogranites range from -25.8 to -19.6 and from 2.81Ga to 2.43Ga respectively, showing that their sources were mainly ancient crustal material with the addition of some juvenile components. The ages of gold, molybdenum deposits near the Huashan pluton are identical with those of the Huashan pluton, but are 20~25Ma younger than the age of Wuzhangshan pluton. The formation of gold molybdenum deposits was close to the formation of Huashan granitoid pluton in time and space. This pluton might have provided a thermal source for the mineralization.