Zircon U–Pb Ages and Geochemistry of Granite Porphyries in the Yangla Cu Deposit, SW China: Constraints on Petrogenesis and Tectonic Evolution of the Jinshajiang Suture Belt

Figure 7

Macroscopic and microscopic characteristics of the granite porphyries in the Yangla copper deposit, Yunnan, China. (a) Grayish-white massive granite porphyry. The quartz crystals are semiautomorphic or elongated grains, and the plagioclase phenocrysts, which underwent strong alteration, appear corroded. (b) Grayish-white massive structure granite porphyry with veinlets of metal sulfides (pyrite and chalcopyrite) and quartz. (c) Grayish-white massive structure granite porphyries with large amounts of veined metal sulfides (pyrite and chalcopyrite). (d) Grayish-white massive structure granite porphyry with large amounts of quartz veins. (e) Gray massive structure granite porphyry with large amounts of disseminated pyrite, chalcopyrite, and bornite. (f) Light-grayish to white massive structure granite porphyry with metal sulfide veins (pyrite and chalcopyrite), quartz veins, and disseminated bornite. (g) Porphyritic texture granite porphyry. The phenocrysts are semiautomorphic or elongated grains, the quartz is corroded, and the matrix is microscopic granular plagioclase–quartz. (h) Granite porphyry with blastoporphyritic texture. The phenocrysts are sericitic plagioclase, and the matrix is plagioclase–quartz with a felsitic texture. (i) Granite porphyry with blastoporphyritic texture. The phenocrysts are sericitic plagioclase, the quartz is corroded, and the matrix is microscopic granular plagioclase–quartz. (j) Porphyritic texture granite porphyry. The phenocrysts are automorphic granular quartz and faded biotite, and the matrix is microscopic granular plagioclase–quartz. (k) Granite porphyry with blastoporphyritic texture. The phenocrysts are sericitic plagioclase and faded biotite, and the matrix is microscopic granular plagioclase–quartz. (l) Quartz–sulfide veins developed in the granite porphyry. (m) Disseminated chalcopyrite and pyrite. (n) Xenomorphic granular pyrite and chalcopyrite developed along fissures in alternating scattered-disseminated and irregular fine-veined forms. The pyrite is interspersed with chalcopyrite. (o) Chalcopyrite and pyrite in-filled along the quartz veins. The pyrite is xenomorphic and interspersed by chalcopyrite. Qz: quartz; Pl: plagioclase; Bi: biotite; Py: pyrite; Cp: chalcopyrite.

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