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Abstract: The Jinshajiang–Red River porphyry Cu–Mo metallogenic belt is an important Cenozoic porphyry Cu–Mo mineralization concentrating zone in the eastern Indo‐Asian collision zone. New zircon U–Pb and molybdenite Re–Os ages and compilation of previously published ages indicate that porphyry Cu–Mo deposits in the belt did not form at the same time, i.e., the porphyry emplacement and relevant Cu–Mo mineralization ages of the Ailaoshan–Red River ore belt in south range from 36.3Ma to 34.6Ma, and from 36.0Ma to 33.9Ma, respectively, which are obviously younger than the porphyry emplacement ages of 43.8–36.9Ma and the relevant Cu–Mo mineralization ages of 41.6–35.8Ma of the Yulong ore belt in north. Tectonic studies indicated that the Jinshajiang fault system in north and Ailaoshan–Red River fault system in south of the Jinsjiang–Red river belt had different strike-slip patterns and ages. The right-lateral strike-slip motion of the Jinshajiang fault system initiated at ca. 43Ma with corresponding formation of the Yulong porphyry Cu–Mo system, whereas the left-lateral strike-slip motion of the Ailaoshan–Red River fault system initiated at ca. 36Ma with corresponding formation of the Ailaoshan–Red River porphyry Cu–Mo system. Therefore, the different ages of porphyry Cu–Mo systems, between in north and south of the Jinshajiang–Red River belt, indicate that the porphyry Cu–Mo mineralization is closely related to the divergent strike-slip movements between the Jinshajiang and Ailaoshan–Red River strike-slip faulting resulted from the Indo‐Asian collision. The tanslithospheric Jinshajiang–Red River faulting caused partial melting of the enriched mantle sources of alkali-rich porphyries by depressurization or/and asthenospheric heating, and facilitated the migration of alkali-rich magmas and the corresponding formation of alkali-rich porphyries and relevant Cu–Mo deposits in the belt. [Copyright &y& Elsevier]

The Baituyingzi Mo (Cu) deposit is a newly identified porphyry deposit located in the southern part of the Xilamulun Mo metallogenic belt, Northeast China. Mo (Cu) mineralization mainly occurs as quartz veinlets and stockwork veinlets in the potassic altered Baituyingzi monzogranite porphyry. A detailed investigation of fluid inclusions and O H isotopes from hydrothermal veins at Baituyingzi allow us to establish the evolving history of the fluid system, as well as understand factors controlling Cu Mo precipitation in CO 2 -rich fluids. Six vein types are recognized at Baituyingzi, which belong to five hydrothermal stages: (1) UST quartz vein, formed during magmatic-hydrothermal transitional stage; (2) A 1 vein (sulfide-barren quartz vein) and A 2 vein (quartz–pyrite–chalcopyrite ± molybdenite vein, Cu mineralization), related to potassic alteration; (3) B vein (quartz–molybdenite ± chalcopyrite ± pyrite vein, Mo mineralization), formed during the potassic-sericitic transitional stage; (4) D vein (quartz–pyrite ± molybdenite ± chalcopyrite vein), associated with sericitic alteration; and (5) late stage L vein (quartz–carbonate vein). Four types of fluid inclusions have been observed in these veins, i.e., liquid-rich inclusions (L-type), vapor-rich inclusions (V-type), polyphase high-salinity inclusions (S-type), and CO 2 -rich inclusions (C-type). UST quartz veins contain abundant S- and co-existing V-type inclusions, accompanied by minor melt inclusions, indicating that the parent fluids were likely in the form of bubbly magma (~ 10 wt% NaCl equiv.) that was derived from a deep magma chamber. A 1 veins are dominated by coexisting S- and V-type inclusions that homogenized at temperatures ranging from 400° to 548.5 °C and pressures between 300 and 750 bar, which may represent the result of parent fluid immiscibility (vapor-brine) at depth. Apart from S- and V-type inclusions, Cu-bearing A 2 veins are especially rich in isolated L-type inclusions (homogenized at 347 to 430 °C) that share the same salinity range as V-type inclusions (homogenized at 375 to 470 °C), suggesting that the vapor gradually contracted to a liquid phase at around 350 bar. Because the system was still in a lithostatic condition (revealed by textures of A 2 veins), Cu precipitation at Baituyingzi was thus largely controlled by temperature reduction (to below 400 °C) near the vapor-liquid surface in relatively oxidized fluids (indicated by the precipitation of abundant hematite). C-type inclusions (homogenize at 275 to 350 °C) seem to be more widely developed, and they commonly co-exist with L-type inclusions (homogenized at 340 to 380 °C) of similar salinity in B veins, implying that they unmixed at temperatures below 350 °C and pressures below 200 bar. Considering that the system had already fluctuated to hydrostatic conditions (revealed by clear open-space filling textures), as well as considering the occurrence of minor feldspar-destructive alteration halos in B veins, Mo precipitation would likely be a result of water-CO 2 immiscibility at temperatures below 350 °C with a sharp pressure reduction to below 200 bar and an increase in fluid acidity. D veins contain plentiful L- and minor C– and S-type inclusions that homogenized at lower temperatures (240 to 350 °C) and pressures (30 to 150 bar). The wide feldspar-destructive alteration halos indicate that the fluids became progressively more acidic and reacted intensely with wall-rocks. L veins only contain low temperature (168 to 280 °C) and low salinity (0.4 to 10.9 wt% NaCl equiv.) L-type inclusions, implying that meteoric water was introduced to the barren magmatic fluids, leading to precipitation of a large amount of remnant material. δ 18 O and δD isotope ratios in quartz (δ 18 O fluid = 3.54‰ to 7.51‰, δD = − 107‰ to − 87‰) also confirm a primary magmatic origin for ore-forming fluids in earlier veins, except for L veins. Therefore, fluid evolution at Baituyingzi was characterized by relatively continuous, system-scale cooling along an ascent path gradually straddling the vapor-brine, vapor-liquid, and water–CO 2 surface in the vapor-dominated H 2 O CO 2 NaCl fluid system, whereas the subtle temporal change in P-T-redox conditions and acid balance of the evolutionary paths of the magmatic fluid may be responsible for Cu and Mo separation at the Baituyingzi CO 2 –rich systems. Additionally, water-CO 2 immiscibility seems to be an additional important mechanism that complicates Mo precipitation in CO 2 –rich systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Pulang composite intrusion defined a magmatic duration of 10 m.y. from ∼226 Ma to ∼216 Ma. • Six porphyry phases (i.e., premineralized and synmineralized porphyries) at Pulang were all derived from relatively oxidized and hydrous magmas. • The synmineralized porphyries showed higher magmatic sulfur and chlorine contents than those for the premineralized porphyry phases. • Magmatic sulfur and chlorine contents might be important for Pulang porphyry Cu-Au formation. The giant Pulang porphyry Cu-Au district (446.8 million tonnes at 0.52% Cu and 0.18 g/t Au) is located in the southern Yidun terrane of the Sanjiang (Three-river) region, southwest China. It has six phases of porphyry intrusions: premineralized fine-grained quartz diorite (FQD) and coarse-grained quartz diorite porphyry (CQD), the main synmineralized quartz monzonite porphyry (QMP), and late synmineralized granodiorite porphyry (GP), diorite porphyry (DP), and aplite. New zircon U-Pb ages for the premineralized FQD and late synmineralized GP, DP, and aplite are 226.3 ± 2.6 Ma (MSWD = 1.9), 216.4 ± 1.0 Ma (MSWD = 2.0), 216.0 ± 1.1 Ma (MSWD = 1.7), and 216.0 ± 1.5 Ma (MSWD = 1.7), respectively. All Pulang porphyry rocks have high whole-rock Sr/Y ratios (37.8–184) with minor or no negative Eu anomalies (0.73–1.04), and are characterized by high large-ion-lithophile-element (LILE: Th, U, Ba, Rb) abundances and low high-field-strength-element (HFSE: Nb, Ta, Ti, Zr, Hf). Zircons from premineralized FQD and synmineralized GP, DP, and aplite rocks have consistently high Eu N /Eu N * ratios (mostly > 0.4). The magmatic oxygen fugacity calculated from zircon compositions, show that the FQD (ΔFMQ = 1.59 ± 0.43), GP (ΔFMQ = 1.52 ± 0.18), DP (ΔFMQ = 1.52 ± 0.30), and aplite (ΔFMQ = 1.75 ± 0.60) were all derived from moderately oxidized magmas. Magmatic water contents estimated from amphibole compositions and the extensive presence of amphibole phenocrysts suggest that H 2 O contents are >4 wt%. Together with the published results for premineralized CQD and main synmineralized QMP, it is concluded the causative magmas for the six porphyry phases at Pulang were all relatively oxidized and hydrous. The difference between premineralized FQD and CQD and synmineralized QMP, GP, and DP are reflected in magmatic chlorine and sulfur contents. To minimize the effect of hydrothermal alteration, the apatite microphenocrysts enclosed by least altered phenocrysts were selected for analyses. The Cl contents of magmatic apatite microphenocrysts from the synmineralized QMP (avg = 0.340 ± 0.192, n = 26), GP (avg = 0.317 ± 0.151, n = 21), and DP (avg = 0.179 ± 0.112, n = 18) are significantly higher than those from the premineralized FQD (avg = 0.046 ± 0.032, n = 9) and CQD (avg = 0.043 ± 0.034, n = 13). Similarly, the SO 3 contents of igneous apatite microphenocrysts from the synmineralized QMP (avg = 0.259 ± 0.156, n = 25), GP (avg = 0.203 ± 0.163, n = 20), and DP (avg = 0.306 ± 0.173, n = 18) are higher than those from the premineralized FQD (avg = 0.181 ± 0.136, n = 10) and CQD (avg = 0.085 ± 0.068, n = 6). The S-Cl contents of synmineralized melts estimated from apatite S-Cl compositions are higher than those of premineralized magmas, suggesting that the elevated magmatic S-Cl contents in the synmineralized porphyries might have been important for Cu-Au mineralization. This was likely due to S-Cl rich mafic magma recharge, supported by the presence of abundant mafic magmatic enclaves in the synmineralized QMP. [ABSTRACT FROM AUTHOR]

• The Lawu volcanic rocks and associated porphyries have a closely comagmatic relation. • The mantle domains were metasomatized by Paleo-Tethyan oceanic marine sediments. • The porphyry-volcanic system has similar H 2 O but lower fO 2 of than Yulong deposit. Generally, porphyry Cu deposits are associated with the comagmatic porphyry (or subvolcanic)-volcanic systems of high magmatic H 2 O-fO 2 conditions. The volcanic rocks, as the counterpart of the porphyries, thus can provide some significant insights into the fertility of the porphyries to some extent. For this reason, we have used the Lawu volcanic rocks and spatial-temporal closely-related porphyries in the newly discovered porphyry Cu prospects (e.g., Seli, Zongguo, Mamupu) in the southern segment of the Yulong intracontinental porphyry Cu belt to illustrate the relationship between the porphyries and volcanic rocks, petrogenesis of the volcanic rocks, and then to evaluate the ore potential of the porphyries based on the magmatic H 2 O-fO 2 conditions. Both the Lawu volcanic rocks and Seli-Zonguo-Mamupu porphyries are shoshonitic and metaluminous, and have similar REE patterns, and Sr-Nd-Hf isotopic compositions, which suggest a comagmatic relation between the volcanic rocks and porphyries. An episodic magmatism model is proposed to explain the slightly younger age (~36–35 Ma) and less evolved nature of volcanic rocks than the porphyries. The Lawu volcanic rocks of mainly intermediate composition (SiO 2 = 54.25–64.68 wt%) have high K 2 O (4.75–5.94 wt%) and high K 2 O/Na 2 O ratios (1.69–2.00), broadly similar to the coeval Yulong fertile granitic porphyries and the Nangqian mafic lavas. The (87Sr/86Sr) i and ε Nd (t) values, uniform zircon ε Hf (t) and δ18O values, and lack of inherited zircons of the Lawu volcanic rocks don't support their formation by mixing between the mantle-derived Nangqian mafic lavas and crust-derived Yulong felsic porphyries or assimilation and fractional crystallization (AFC) of mafic magmas. They are characterized by high Ba/Th, Ba/La and listric-shaped normalized rare earth element profile with significantly negative Nb-Ta-Ti anomalies, and have high initial 87Sr/86Sr ratios (0.7071–0.7079) and low ε Nd (t) values (−5.71 to −3.05), and low zircon ε Hf (t) (−1.53 to 4.09) and clearly high δ18O values (6.67–8.42‰), suggesting that, they were probably formed by fractional crystallization (FC) of mantle-derived mafic magmas and originated from mantle domains modified by significant amount of H 2 O-rich marine sediments of the Paleo-Tethyan oceanic slab. Magmatic H 2 O contents calculated from deepest-crystallized amphiboles indicate that, the Lawu volcanic rocks and Zongguo porphyries have initial magmatic H 2 O contents as high as the Yulong fertile porphyries and typical porphyry Cu systems worldwide (commonly >4 wt% H 2 O). Magmatic fO 2 (ΔFMQ) of the Lawu volcanic rocks (0.6–1.3, ave. 0.9 ± 0.1) and the Zongguo porphyries (0.9–1.7, ave. 1.4 ± 0.2) are clearly lower than the fertile porphyries in the giant Yulong deposit (ΔFMQ = 1.6–3.3, ave. 2.3 ± 0.5) and typical porphyry Cu deposits in the world (commonly ΔFMQ > 2). The slightly lower magmatic H 2 O contents and slightly higher magmatic fO 2 of the Zongguo porphyries than the Lawu volcanic rocks were ascribed to variable degassing during magmatic evolution. These suggest that, in spite of the high magmatic H 2 O contents, the comagmatic porphyries (at least the Zongguo porphyries) of the Lawu volcanic rocks in the southern segment of the Yulong porphyry Cu belt are unlikely to produce large-scale porphyry Cu mineralization like the giant Yulong deposit, due to the low magmatic fO 2 conditions. [ABSTRACT FROM AUTHOR]