Among these porphyries, the alkaline granite porphyry (37.9–35.0 Ma) is considered to be ore-related [34,35,47,48].
The Machangqing intrusive complex was emplaced in the Xiangyang Formation at the onset of the mineralization.
Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) allanite U-Th-Pb dating has yielded Th-Pb isochron ages of 33.4 ± 4.6 Ma (MSWD = 0.22) (Beiya) and 35.4 ± 9.8 Ma (MSWD = 0.26) (Machangqing), representing the retrograde alteration and magnetite skarn mineralization age of the two deposits.
The Beiya and Machangqing alkali porphyry-related mineralization are synchronous and genetically linked to the magmatic hydrothermal activities of the Himalayan orogenic event.
Many large porphyry and skarn deposits are associated with this belt, which makes it one of the most important metallogenic belts in China.