Miocene Ultrapotassic, High-Mg Dioritic, and Adakite-like Rocks from Zhunuo in Southern Tibet: Implications for Mantle Metasomatism and Porphyry Copper Mineralization in Collisional Orogens

High-Mg diorites and/or ultrapotassic volcanic rocks are generally associated with postcollisional porphyry copper deposits, but their contribution to the formation of the mineralization remains unclear. A suite of Miocene postcollisional ultrapotassic–potassic lamprophyres, high-Mg diorites, and adakite-like intrusions have been recognized in the Zhunuo porphyry Cu deposit, located in a continental collisional zone within the Gangdese belt,...