Geochronology and geochemical characteristics of Late Triassic porphyritic rocks from the Zhongdian arc, eastern Tibet, and their tectonic and metallogenic implications

Ore-bearing porphyritic rocks are widely distributed in the Zhongdian arc in the southern part of the Yidun arc, eastern Tibet. New U–Pb zircon dates, and previous results, show that the porphyritic rocks formed mainly between 221 and 211 Ma, with a peak at 217–215 Ma. These Late Triassic porphyritic rocks and associated volcanic rocks are primarily calc-alkaline igneous rocks, some of which have geochemical affinities with adakite, such as high...