Abstract The temporal-spatial distribution of metallic ore deposits in China, including magmatic Ni-Cu ± platinum group elements (PGE), porphyry, skarn, volcanogenic massive sulfide (VMS), epithermal, sedimentary rock-hosted Pb-Zn, Carlin-like Au, and orogenic Au deposits, reflects a diversity of tectonic settings. The ore deposits belong to 14 metallogenic provinces, contained within six age groups, which are classified based on geodynamic setting. Three of the provinces developed in the Precambrian (group I), nine developed in the Paleozoic and Mesozoic (groups II, III, IV, and V), and two developed in the Cenozoic (group VI). Except for the group I provinces, each of the other provinces is characterized by a major metallogenic age peak corresponding to a series of interrelated tectonic events or mantle plume activity. The Precambrian group can be subdivided into a Neoarchean metallogenic province in the North China craton that hosts several VMS deposits; a Proterozoic metallogenic province in the North China craton that hosts the 1505 Ma Bayan Obo carbonatite-related rare earth element (REE)-Nb-Fe deposit and the 832 Ma Jinchuan magmatic Ni-Cu-(PGE) deposit, and a Proterozoic metallogenic province in the South China block that hosts several iron oxide copper-gold deposits. Many of the deposits in these metallogenic provinces are related to continental rifting. The second group of metallogenic provinces occurs in the Chinese part of the Central Asian orogenic belt. It includes a Cambrian-Ordovician metallogenic province that developed during subduction of the Paleo-Asian oceanic plate, a Carboniferous-Triassic metallogenic province (Tianshan-Altay) that developed during final closure of the ocean, and a Permian-Triassic metallogenic province (NE China) that developed after arc-continent collision. Important ore deposits in these metallogenic provinces are, respectively, the 485 Ma Duobaoshan porphyry Cu-Mo deposit the 445 Ma Bainaimiao porphyry Cu-Mo-Au deposit; the 363 Ma Axi epithermal Au deposit, the 322 Ma Tuwu-Yangdong porphyry Cu deposit, the 284 Ma Huangshanxi magmatic Ni-Cu deposit; the 245 Ma Chehugou porphyry Mo-Cu deposit, the 223 Ma Jinchangyu orogenic Au deposit, and 220 Ma Hongqiling magmatic Ni-Cu deposit. The third group of metallogenic provinces occurs in the Tethyan metallogenic domain and can be further divided into a Cambrian-Ordovician Qilian-Kunlun-Sanjiang province that developed during subduction and closure of the Proto-Tethyan Ocean; a Carboniferous-Triassic province that developed during birth, subduction, and consumption of the Paleo-Tethyan Ocean; and a Jurassic-Cretaceous Tethys province that developed during subduction of the Meso-Tethys oceanic plate. Important ore deposits in these provinces include the 411 Ma Baiganhu W-Sn skarn deposit and the 412 Ma Xiarihamu magmatic Ni-Cu deposit that formed in a continental-arc setting; the Laochang Pb-Zn VMS deposit associated with ocean island basalt-like volcanism, the 220 Ma Pulang porphyry Cu deposit that formed in a continental-arc setting, and the 230 to 210 Ma Carlin-like Au deposits formed in a postcollisional environment in the western Qinling and the Youjiang basin; and the 119 Ma Tieyaoshan Sn skarn-greisen deposit, the 88 Ma Tongchanggou porphyry Mo deposit, and the 83 Ma Gejiu Sn skarn deposits. The fourth group of metallogenic provinces developed during subduction of the Pacific oceanic plate beneath southeastern China and comprises a Jurassic and a Cretaceous province. The former is represented by a cluster of ~160 Ma W-Sn skarn deposits in the Nanling region; the latter is known for many ~135 Ma skarn and porphyry Cu-Au deposits in the Tongling region and numerous ~125 Ma unusual orogenic Au deposits in the Jiaodong and Xiaoqinling regions. The fifth group is the Emeishan metallogenic province that is related to Permian mantle plume activity in southwestern China. Several world-class magmatic Fe-Ti-V oxide deposits, a few small magmatic Ni-Cu deposits, and a couple of small magmatic Pt-Pd deposits associated with mafic-ultramafic intrusions are present in this province. The sixth group of metallogenic provinces developed in the Cenozoic during continental collision in the Tibet and Sanjiang region. This group can be further divided into the Sanjiang province that is related to oblique collision, and the Tibet province that is related to orthogonal collision. Important ore deposits in these provinces are the ~41 Ma Yulong porphyry Cu-(Mo) deposit, the 37 Ma Beiya Au-Cu skarn deposit, the ~26 Ma Jinding sedimentary rock-hosted Zn-Pb deposit, the ~30 Ma Zhenyuan orogenic Au deposit, and the ~15 Ma Qulong and Jiama porphyry Cu deposits. The youngest metallogenic province in China occurs on the Taiwan Island. This province developed during the subduction of the Philippine Sea oceanic plate beneath the island in the Pliocene and the accretion of the Luzon volcanic arc to the island in the Pleistocene. This province contains numerous Pliocene orogenic gold deposits as well as the Pleistocene Chinkuashih epithermal gold deposit in northern Taiwan.

Abstract Zircon composition has great potential as a pathfinder for porphyry Cu ± Mo ± Au systems. The present study used a large integrated laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb age and trace element dataset for both infertile and fertile magmatic suites in order to elucidate distinctive zircon signatures diagnostic of metallogenic fertility of the parent magma. The infertile suites are defined as magmatic rocks that are absent of alteration and mineralization at any grade, whereas fertile suites refer to the causative intrusions leading to porphyry-type ore formation. The infertile suites are relatively reduced S- and A-type and relatively dry A- and I-type magmas, including the Yellowstone rhyolite (Wyoming), Bandelier rhyolite (New Mexico), Bishop tuff rhyolite (California), Lucerne reduced granite (Maine), and Hawkins S-type dacite and Kadoona I-type dacite (Lachlan belt, Australia). The fertile suites are more oxidized and hydrous and are selected from representative causative I-type intrusions from porphyry and high-sulfidation epithermal Cu-Au deposits (Batu Hijau, Indonesia, and Tampakan, Philippines), porphyry Cu-Mo-Au deposits (Sar Cheshmeh, Iran; Dexing, eastern China; and Jiama, southern Tibet), porphyry Cu-Mo deposits (Sungun, Iran, and Qulong, southern Tibet), and porphyry Mo deposits (Nannihu and Yuchiling, central China). The best fertility indicators are zircon Eu/Eu* and (Eu/Eu*)/Y ratios, whereas zircon (Ce/Nd)/Y and Dy/Yb ratios are moderately useful. In particular, fertile magmatic suites have collectively higher zircon Eu/Eu* ratios (>0.3), 10,000*(Eu/Eu*)/Y (>1), (Ce/Nd)/Y (>0.01), and lower Dy/Yb (<0.3) ratios than infertile suites. In fertile suites, zircon (Eu/Eu*)/Y ratios are positively correlated with (Ce/Nd)/Y ratios, but this correlation is lacking in the infertile suites. The distinctive zircon ratios in the fertile suites are interpreted to indicate extremely high magmatic water content, which induces early and prolific hornblende fractionation and suppresses early plagioclase crystallization. In addition, we found that Mo is able to substitute for Zr in the zircon lattice. The Mo-rich porphyry systems that were analyzed as part of this study tend to produce some zircons with a higher Mo content (>1-9 ppm) than Mo-poor porphyry systems and infertile suites, indicating that Mo content in zircon is a potential pathfinder to porphyry Mo ore deposits. The zircon Mo/Ti ratio has a broad positive correlation with the oxygen fugacity of the magma, indicating that this ratio may be potentially used as a proxy for the oxidation state of the melt. Analyzing the compositions of detrital zircons from an area with little geologic information or poor outcrop could efficiently and cheaply discriminate whether the drainage source area is dominated by unprospective A-, S-, and I-type granitoids or by prospective I-type granitoids, which could help focus exploration on prospective areas.

Abstract Porphyry Cu deposits in China contain a total resource of ~47 million tonnes (Mt) Cu at average grades ranging mostly from 0.2 to 0.7% Cu (most <0.5% Cu), accounting for 42% of China’s Cu reserves. In terms of contained Cu, 14 Cu-rich porphyry deposits are classified as giant (≥2.0 Mt Cu), and 38 are classified as intermediate (≥0.06 Mt Cu). These giant and intermediate deposits are mainly concentrated in seven belts or districts: Gangdese belt, southern Tibet; Yulong and Zhongdian belts, eastern Tibet; Duolong district, central Tibet; Dexing district and Middle-Lower Yangtze River Valley belt, eastern China; and the Central Asian orogenic belt in northern China. Other isolated giant deposits (e.g., Tongkuangyu) occur in the North China craton. These deposits were formed during Paleoproterozoic (~2100 Ma), Ordovician (~480–440 Ma), Carboniferous (~330–310 Ma), Late Triassic to Early Cretaceous (~215–105 Ma), and Eocene to Miocene (~40–14 Ma), with the majority forming during the latter two time periods. Adakite-like (e.g., high Sr/Y ratio) magmas are most favorable for the formation of the porphyry Cu deposits in China, although some deposits in the Central Asian orogenic belt and the Duolong district are associated with normal calc-alkaline intrusions with low Sr/Y ratios. Approximately 50% of the giant and ~35% of the intermediate porphyry Cu deposits in China formed in arc settings. The Xiongcun, Pulang, Duobuza, Bolong, and Naruo deposits in Tibet formed in continental arc settings, and the Central Asian porphyry Cu belt deposits (e.g., Tuwu-Yandong, Duobaoshan, Wushan, Baogutu, and Bainaimiao) formed in island-arc settings. Ore-forming porphyry magmas in arc settings in China probably formed by partial melting of metasomatized mantle wedge. Ascent and emplacement of porphyry magmas in arc settings was controlled by transpressional (e.g., strike-slip fault systems) or compressional deformation (e.g., arc-parallel thrust fault systems). Approximately 40% of the giant and ~65% of the intermediate porphyry Cu deposits in China occur in postcollisional settings. These deposits are mainly concentrated in the Tibetan Plateau, including four giant (e.g., Qulong, Jiama, Zhunuo, and Yulong) and more than 15 intermediate-size deposits. The mineralized intrusions in postcollisional settings were generated by partial melting of subduction-modified mafic lower crust. Ore-forming metals and sulfur were derived from remelting of sulfide phases that were introduced during precollisional arc magmatism, and the water in the Cu-forming porphyry magmas was concentrated during dehydration reactions in the upper parts of the subducting continental plate and/or degassing of mantle-derived H 2 O-rich ultrapotassic and/or alkaline mafic magmas. Porphyry magma ascent and emplacement were controlled by regional shear zones (e.g., strike-slip fault systems) or extensional fracture arrays (e.g., normal fault systems) in postcollisional settings. Porphyry Cu deposits in China mostly show typical alteration zoning from inner potassic to outer propylitic zones, with variable phyllic and argillic overprints. Potassic alteration can be generally subdivided into inner K-feldspar and outer biotite zones, with K-feldspar–rich alteration mostly earlier than biotite-rich alteration. Phyllic alteration generally comprises early-stage chlorite-sericite and late-stage quartz-sericite alteration, and the chlorite-sericite zone typically occurs beneath the quartz-sericite zone. Lithocaps are absent in most of the porphyry Cu deposits in China, even for those in the youngest (~30–14 Ma) ores in the Gangdese belt. Alteration architecture of the porphyry Cu deposits in China is mainly dependent on the structural setting and degree of telescoping. Telescoping of alteration assemblages in the postcollisional porphyry Cu deposits is more strongly developed than that in island and continental arc porphyry Cu deposits. This is probably because postcollisional porphyry Cu deposits and districts in China either experienced higher rates of synmineralization uplift or suffered more complex structural superposition, compared with those formed in magmatic arcs. Hypogene Cu mineralization in some giant porphyry deposits in China (e.g., Xiongcun, Qulong) is associated with potassic alteration and particularly with late-stage biotite alteration. But hypogene mineralization for more than 50% of giant porphyry Cu deposits, including the Dexing, Yulong, Tuwu-Yandong, Duobaoshan, and Tongkuangyu deposits, is characterized by a Cu sulfide assemblage with phyllic alteration, particularly with chlorite-sericite alteration. The presence of several world-class postcollisional porphyry Cu provinces in China demonstrates that the generation of porphyry Cu deposits does not always require a direct link to oceanic plate subduction.