Geological, Geochronological, and Geochemical Insights into the Formation of the Giant Pulang Porphyry Cu (–Mo–Au) Deposit in Northwestern Yunnan Province, SW China

Abstract

The giant Pulang porphyry Cu (–Mo–Au) deposit in Northwestern Yunnan Province, China, is located in the southern part of the Triassic Yidun Arc. The Cu orebodies are mainly hosted in quartz monzonite porphyry (QMP) intruding quartz diorite porphyry (QDP) and cut by granodiorite porphyry (GP). New LA-ICP-MS zircon U–Pb ages indicate that QDP (227 ± 2 Ma), QMP (218 ± 1 Ma, 219 ± 1 Ma), and GP (209 ± 1 Ma) are significantly different in age; however, the molybdenite Re–Os isochron age (218 ± 2 Ma) indicates a close temporal and genetic relationship between Cu mineralization and QMP. Pulang porphyry intrusions are enriched in light rare-earth elements (LREEs) and large ion lithophile elements (LILEs), and depleted in heavy rare-earth elements (HREEs) and high field-strength elements (HFSEs), with moderately negative Eu anomalies. They are high in SiO2, Al2O3, Sr, Na2O/K2O, Mg#, and Sr/Y, but low in Y, and Yb, suggesting a geochemical affinity to high-silica (HSA) adakitic rocks. These features are used to infer that the Pulang HSA porphyry intrusions were derived from the partial melting of a basaltic oceanic-slab. These magmas reacted with peridotite during their ascent through the mantle wedge. This is interpreted to indicate that the Pulang Cu deposit and associated magmatism can be linked to the synchronous westward subduction of the Ganzi–Litang oceanic lithosphere, which has been established as Late Triassic.

Age and Tectonic Setting of Mesothermal Magmatic Hydrothermal Vein‐Type Pb–Zn–(Ag) Mineralization in the Xiaohongshilazi Deposit, Central Jilin Province, Northeast China

“…The granodiorite porphyry hosting the vein‐type Pb–Zn–(Ag) mineralization is geochemically featured by the high‐SiO 2 , high‐Na 2 O (Na 2 O/K 2 O = 1.07–1.10), high‐K, calc‐alkaline, and metaluminous to weakly peraluminous (A/CNK = 0.95–1.04) composition. These geochemical characteristics, together with the presence of amphibole and absence of cordierite and muscovite, indicate that the granodiorite porphyry belongs to the I‐type granitoid (Chappell & White, ; Qiu & Deng, ; Yang et al ., ). Petrological experiment data indicate that the calc‐alkaline, intermediate silicic, I‐type granitoids typically originate from the partial melting of mafic to intermediate igneous rocks in the crust (Patino‐Douce & Harris, ; Patino‐Douce & McCarty, ; Qiu et al ., ) or assimilation of fractionated mantle‐derived basaltic magmas (Li et al ., ; Qiu & Deng, ).…”

“…The granodiorite porphyry hosting the vein-type Pb-Zn-(Ag) mineralization is geochemically featured by the high-SiO 2 , high-Na 2 O (Na 2 O/K 2 O = 1.07-1.10), high-K, calc-alkaline, and metaluminous to weakly peraluminous (A/CNK = 0.95-1.04) composition. These geochemical characteristics, together with the presence of amphibole and absence of cordierite and muscovite, indicate that the granodiorite porphyry belongs to the I-type granitoid (Chappell & White, 1974;Qiu & Deng, 2017;Yang et al, 2019a Harris, 1998;Patino-Douce & McCarty, 1998;Qiu et al, 2014) or assimilation of fractionated mantle-derived basaltic magmas (Li et al, 2007;Qiu & Deng, 2017). No coeval mafic rocks are associated with the granodiorite porphyry, and only minor volumes of diabase occur in the Xiaohongshilazi ore district (Fig.…”

Editorial for Special Issue “Polymetallic Metallogenic System”

“…The studies by Yu et al [23], Wang et al [24], Yang Q. et al [25], and Yang F. et al [26] provide geological, geochronological, and geochemical insights into the formation of polymetallic deposits, including the timing of mineralization and ore genetic types. In addition, garnet Sm-Nd dating is conducted on the Hongshan skarn deposits to further constrain the timing of skarn formation in Zu et al [27].…”