Zircon U–Pb ages and Hf isotope of the granitoids from the Xingwen porphyry molybdenum deposit in the Xiaoxing'an Range – Zhangguangcai Range metallogenic belt, NE China

Abstract

The newly discovered Xingwen porphyry Mo deposit is located in the most southern segment of the Xiaoxing'an Range–Zhangguangcai Range metallogenic belt (XZMB), NE China. The Mo deposit occurs with a granitic complex consisting of monzogranite, porphyritic granite and felsite porphyry. The Zircon U–Pb ages of monzogranite, porphyritic granite and felsite porphyry are 170.3 ± 2.1, 168.5 ± 2.5, and 166.7 ± 1.6 Ma, respectively. The inherited zircons from the monzogranite and porphyritic granite yield U–Pb ages of 239.8 ± 5.8 and 249.4 ± 6.2 Ma, respectively. These ages reveal that the Mo mineralization in the most southern segment of the XZMB took place in the Middle Jurassic, and is consistent with the epoch of the largest Daheishan Mo district in the XZMB. In contrast, Triassic ages of the inherited zircons are consistent with the ages of the Triassic magmatic activities along the E–W trending tectono‐magmatic belt in the northern margin of the North China Craton. The εHf(t) of the monzogranite, porphyritic granite and felsite porphyry change from −17.1 to +6.7 , −16.9 to +2.9, −5.94 to −0.90, respectively. The Hf isotopic compositions indicate that old crustal source, juvenile crustal source or depleted mantle contributed to their origin. When compared with the granite in Daheishan Mo district in XZMB, the εHf(t) probably indicates that the granitic complex in the margin of the Central Asia Orogenic Belt may have more old crustal materials than the granitic complex in the inner region of the Central Asia Orogenic Belt. Copyright © 2017 John Wiley & Sons, Ltd.