Geology, geochemistry and geochronology of the Jiaojiguanliangzi Fe-polymetallic deposit, Tengchong County, Western Yunnan (China): Regional tectonic implications

Abstract

The Jiaojiguanliangzi Fe-polymetallic deposit, located near the Sino-Burmese border of the Tengchong County, western Yunnan in China, is a medium to large scale skarn Fe-polymetallic deposit that was recently discovered in this area. Zircons from monzonite granite-porphyry in the mining area yield an U–Pb age of 120±0.6Ma, and show εHf(t) values ranging from −1.9 to −4.9, suggesting that the magma was derived from dominantly pelitic sedimentary protoliths. The porphyry is part of muscovite-bearing peraluminous S-type granitoid formed at the late stage of Early Cretaceous. The molybdenite Re–Os age of 122±0.7Ma from this deposit is consistent with the age of the monzonite granite-porphyry. The monzonite granite-porphyry that hosts the skarn deposit belongs to syn- to post-collisional granitoid, representing the culmination of the collision of Tengchong block with Baoshan block, and the initiation of post-collisional extension event. The Mesozoic granite and Fe-rich polymetallic deposits in the Tengchong area are similar to their counterparts in Bangong–Nujiang magmatic/metallogenic belt in terms of formation age and geological characteristics. This indicates that these two areas underwent a similar intense magmatic activities and mineralization events during the Cretaceous. The Tengchong area has considerable prospecting potential. We believe that the Tengchong area is an important part of the southeast extension of the Bangong–Nujiang metallic belt.