Porphyry Cu-Mo Deposit Research Articles

The Metallogeny of the Tieling Cu-Mo Porphyry Deposit in Eastern Tianshan, NW China: New Insights from Zircon U-Pb, Fluid Inclusion, and H-O-S Stable Isotope Analyses

The eastern Tianshan metallogenic belt is an important molybdenum resource base in Xinjiang and is characterized by large-scale porphyry Mo deposits formed during the Triassic. The Tieling Cu-Mo porphyry deposit, which is situated in the western part of the eastern Tianshan metallogenic belt, was recently recognized as being related to Carboniferous granite porphyry. Three stages of hydrothermal mineralization were identified, including quartz+K-feldspar+pyrite±molybdenite±magnetite (stage I), quartz+molybdenite+pyrite+chalcopyrite (stage II), and quartz+pyrite±molybdenite±epidote (stage III). Fluid inclusion petrography and microthermometry analyses indicate the presence of gas-liquid inclusions with a H2O-NaCl composition. The ore-forming fluids have a characteristic temperature ranging from 157 to 262°C under stage II and 135 to 173°C under stage III, which correspond to salinities of 7.2-17.2 wt% NaCl equiv. and 5.9 to 9.6 wt% NaCl equiv., respectively. The hydrogen and oxygen isotope data indicate that the ore-forming fluids of the Tieling deposit were originally derived from magmatic hydrothermal fluids and then mixed with meteoric water. The sulfur isotope compositions indicate that the ore-forming materials were mainly derived from the Late Carboniferous felsic magma. Furthermore, zircon U-Pb analysis of ore-bearing granite porphyry yields a concordant age of298.4±0.7 Ma, indicating that the Tieling Cu-Mo deposit formed during the Late Carboniferous and differed from that processed under pre-Early Carboniferous and Triassic mineralization in the eastern Tianshan metallogenic belt. These results also indicate that the Tieling porphyry deposit was formed in the transition condition between subduction-related accretion and postcollisional orogeny, and it should be given more attention in prospect evaluations.

Time scales of multistage magma-related hydrothermal fluids at the giant Yulong porphyry Cu-Mo deposit in eastern Tibet: Insights from titanium diffusion in quartz

Accurate determination of the time scales of multiple magmatic-hydrothermal pulses is a critical and difficult problem, which can provide information needed to better constrain the genesis of porphyry deposits. Here, we take advantage of zircon U-Pb dating and improvements in the field of diffusion chronology to determine time scales of multistage magma-related hydrothermal events at the giant Yulong porphyry Cu-Mo deposit in eastern Tibet. New LA-ICP-MS zircon U-Pb data showing that the mineralised Yulong porphyry crystallised at ca. 41 Ma, with the emplacement of the subeconomic Ganlongla intrusion at ca. 41 Ma, indicating a contemporaneous magmatism and mineralisation. Quartz from porphyry and hydrothermal veins exhibits cathodoluminescence (CL) images with a variety of brightness and textures, whereas trace element analyses show that the CL intensity is strongly related to the Ti contents of quartz. The Ti-in-quartz analyses of quartz precipitated in equilibrium conditions yield TitaniQ temperatures that agree with the temperatures calculated using independent thermometers. The sharpness of the Ti gradients observed in the CL images coupled with Ti diffusion modelling for different quartz generations indicate that the bulk of the mineralisation at Yulong formed in a short period of between 880,000 and 16,000 years. These data, together with available isotopic dating data, suggest that the mineralisation is coeval with the emplacement of the porphyries. Complex multi-stage hydrothermal stockwork veins and shorter time scales reveal that the individual magma and fluid pulses at Yulong formed rapidly within tens of thousands of years.

Multi-scale exploration of giant Qulong porphyry deposit in a collisional setting

With the increasing demand for copper resources, exploration methods based on the discovered porphyry Cu deposits (PCDs) to target concealed orebodies are of greater importance. Single parameter is no longer sufficiently effective against concealed deposit exploration, and different combinations of survey techniques are required. The Qulong porphyry Cu-Mo deposit is the largest collisional PCD found in China. Here we evaluated the relationship between variations in multiple parameters and alteration to define exploration footprints around the porphyry Cu centers. In order to improve the exploration efficiency and accuracy, we combined geophysical (magnetic susceptibility and resistivity) and popular geochemical exploration methods (i.e., short wavelength infrared spectroscopy- SWIR, portableX-ray fluorescence- pXRF, and indicator minerals) to the drill hole ZK005 of Qulong PCD in southern Tibet seeking for a firm interpretation. Four orebody indicators were established in study of Qulong deposit, which are: (i) the fluctuations of Ca/K, Mg/Fe, Sr/Ti, and Si/Al ratios, (ii) long-wavelength white mica (2207–2214 nm) and short-wavelength chlorite (2247–2253 nm), (iii) sub-high magnetic susceptibility and (iv) low resistivity. Multi-scale prospecting methods can improve prospecting efficiency and narrow down the target area. Based on the local environment, selecting an appropriate combination of methods can improve exploration efficiency in the brownfields at a lower cost.

Multiple tectonic-magmatic Mo-enrichment events in Yuleken porphyry Cu-Mo deposit, NW China and its’ implications for the formation of giant porphyry Mo deposit

The Yuleken porphyry Cu-Mo deposit located in the Chinese Altay-East Junggar, a section of the Central Asian Orogenic Belt, the world's largest Phanerozoic subduction-accretionary orogen, witnessed the multistage tectonic-magmatic evolution and mineralization from arc to syn- and post-collision environment over a time span of about 52 Ma. Four types of molybdenite have been distinguished: (1) primary magmatic-hydrothermal, undeformed molybdenite in porphyry, (2) recrystallized molybdenite associated with ductile deformation, (3) recrystallized, intrafoliational molybdenite, and (4) fracture-related hydrothermal molybdenite, and these are characterized by decreasing Re abundances from magmatic to hydrothermal conditions. Individual molybdenite types are non-stoichiometric and exhibit the following negative correlation between the Mo and Re contents:Re (apfu) = −0.0026 Mo (apfu) + 0.00268.This trend reflects successive stages of tectonic-hydrothermal events from a magmatic island-arc to a post-collisional setting. These repetitive mineralization events produced Mo enrichment and higher overall Mo grade of the Yuleken deposit, and are recorded in progressively decreasing Re concentrations in molybdenite. Statistical evaluation of Mo and Re abundances in giant to small porphyry deposits worldwide also indicates that decreasing Re in molybdenite will lead to lower overall Re resource (in a single deposit) and to greater overall Mo resource (in the same deposit). Multiple mineralization processes related to repetitive tectonomagmatic episodes in large porphyry Mo deposits that display Re depletion in molybdenite suggest that reworking of mantle-derived porphyry systems by successive events of crustal growth may be the responsible for Mo enrichment and higher overall Mo ore grade, and eventually produce giant porphyry molybdenum deposits.

Geochemistry of Rhenium and Other Trace Elements in Molybdenite, Sar Cheshmeh Porphyry Cu‐Mo Deposit, Iran

AbstractLA‐ICP‐MS analysis of molybdenite from the Sar Cheshmeh porphyry Cu‐Mo deposit (PCD), Iran, shows moderate concentration of Re (average ∼207 ppm) and low concentration of chalcogenides (average of Pb + Te + Bi, ∼31 ppm) as well as metalloids (average of As + Sb + Ge, ∼4.5 ppm). The early‐formed quartz–molybdenites associated with potassic alteration are characterized by moderately low concentration of Re (21–215 ppm with an average of 83 ppm), whereas the transitional quartz–molybdenite veins related to the sericitic stage of mineralization contain more Re (62–465 ppm, with an average of 207 ppm). In contrast, the late‐formed quartz–molybdenite veins associated with phyllic alteration show the highest concentration of Re (up to 1273 ppm with an average of 395 ppm). Gradual increase in Re content of molybdenites deposited throughout the evolution of the porphyry system is probably related to elevated ƒO2 and acidic conditions of the ore fluids governing the transitional and late stage of mineralization, when compared to the moderately low ƒO2 and basic conditions of the ore fluids precipitating the low‐Re molybdenites associated with potassic alteration. The mixed mantle/crustal source of the ore‐related magma and its fractionated composition in Sar Cheshmeh are consistent with magmatic conditions for the formation of Mo‐rich and Re‐poor PCDs in the world.

Inherited source affinity of Li and Hf isotopes for porphyry copper deposits from subduction and collisional settings

Porphyry Cu deposits can be classified at the global scale as oceanic subduction- and continental collision-types based on their tectonomagmatic settings. In order to further characterize the possible differences in the geochemical and isotopic features of these two types of porphyry Cu deposits, Li-Hf isotopes were investigated together with bulk rock major/trace element concentrations and geochronology, for porphyritic granitoids related with four porphyry Cu deposits. The Baogutu porphyry Cu-Au deposit, Xinjiang Province, China, and the Atlas porphyry Cu-Au deposit, Philippines, are taken to represent the oceanic subduction-type, whereas the Demingding porphyry Cu-Mo deposit, Tibet Province, China, and the Grasberg porphyry Au-Cu deposit, Indonesia, are taken as proxies for the continental collision-type. The Li isotopic compositions of the Baogutu granodiorite shows a limited range of + 3.2 to + 6.5‰ (avg. + 4.6 ± 1.7‰, n = 13) in δ7Li values, whereas the diorite from Atlas have δ7Li values of + 2.6 to + 7.7‰ (avg. + 5.9 ± 2.8‰, n = 16), i.e., slightly higher than the Baogutu granodiorites, probably reflecting the involvement of subducted marine sediments. The relatively homogeneous and MORB-like δ7Li values (~+3 to 5‰) of the Baogutu and Atlas porphyries, together with depleted zircon εHf(t) values for Baogutu (+11.8 to + 17.5, avg. + 14.5, n = 19) and Atlas (+7.1 to + 10.6, avg. + 9.0, n = 40), are suggestive of an affinity with oceanic plate, and/or partial melting of the mantle wedge in response to oceanic subduction. By contrast, the δ7Li values of the Demingding monzogranite and quartz porphyry, and the Grasberg quartz monzodiorite vary more broadly, ranging from −0.7‰ to + 10.3‰ (avg. + 2.5 ± 5.9‰, n = 19) and from −0.3 to + 7.3‰ (avg. + 3.7 ± 4.6‰, n = 8), respectively. These two localities also show variable zircon εHf(t) values ranging from −5.4 to + 5.7 (avg. + 2.8, n = 20) and from −20.0 to −1.0 (avg. −10.7, n = 42), respectively. The large variations of δ7Li and εHf(t) values at Demingding and Grasberg are generally similar to those of mid- to lower continental crust (δ7Li ~+3.3‰ and εHf(t) −20.0 to + 5.7), and are thus consistent with their source regions, which are interpreted to reflect continental collisional settings. The Li-Hf isotopic compositions of the four porphyry intrusions show that tectonic settings have dominant effects on the Li-Hf isotopic compositions of the related magmatic rocks, prior to any redistribution by porphyry Cu deposits-related hydrothermal alterations, suggesting that Li-Hf isotopes systematics can partly act as tracers of the source regions related to tectonic settings.

The Relation between Trace Element Composition of Cu-(Fe) Sulfides and Hydrothermal Alteration in a Porphyry Copper Deposit: Insights from the Chuquicamata Underground Mine, Chile

Porphyry Cu-Mo deposits are among the world’s largest source of Cu, Mo, and Re, and are also an important source of other trace elements, such as Au and Ag. Despite the fact that chalcopyrite, bornite, and pyrite are the most common sulfides in this deposit type, their trace element content remains poorly constrained. In particular, little is known about minor and trace elements partitioning into Cu-(Fe) sulfides as a function of temperature and pH of the hydrothermal fluid. In this study, we report a comprehensive geochemical database of chalcopyrite, bornite, and pyrite in the super-giant Chuquicamata porphyry Cu-Mo deposit in northern Chile. The aim of our study, focused on the new Chuquicamata Underground mine, was to evaluate the trace element composition of each sulfide from the different hydrothermal alteration assemblages in the deposit. Our approach combines the electron microprobe analysis (EMPA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of sulfide minerals obtained from six representative drill cores that crosscut the chloritic (propylitic), background potassic, intense potassic, and quartz-sericite (phyllic) alteration zones. Microanalytical results show that chalcopyrite, bornite, and pyrite contain several trace elements, and the concentration varies significantly between hydrothermal alteration assemblages. Chalcopyrite, for example, is a host of Se (≤22,000 ppm), Pb (≤83.00 ppm), Sn (≤68.20 ppm), Ag (≤45.1 ppm), Bi (≤25.9 ppm), and In (≤22.8 ppm). Higher concentrations of Se, In, Pb, and Sn in chalcopyrite are related to the high temperature background potassic alteration, whereas lower concentrations of these elements are associated with the lower temperature alteration types: quartz-sericite and chloritic. Bornite, on the other hand, is only observed in the intense and background potassic alteration zones and is a significant host of Ag (≤752 ppm) and Bi (≤2960 ppm). Higher concentrations of Ag and Sn in bornite are associated with the intense potassic alteration, whereas lower concentrations of those two elements are observed in the background potassic alteration. Among all of the sulfide minerals analyzed, pyrite is the most significant host of trace elements, with significant concentrations of Co (≤1530 ppm), Ni (≤960 ppm), Cu (≤9700 ppm), and Ag (≤450 ppm). Co, Ni, Ag, and Cu concentration in pyrite vary with alteration: higher Ag and Cu concentrations are related to the high temperature background potassic alteration. The highest Co contents are associated with lower temperature alteration types (e.g., chloritic). These data indicate that the trace element concentration of chalcopyrite, bornite, and pyrite changed as a function of hydrothermal alteration is controlled by several factors, including temperature, pH, fO2, fS2, and the presence of co-crystallizing phases. Overall, our results provide new information on how trace element partitioning into sulfides relates to the main hydrothermal and mineralization events controlling the elemental budget at Chuquicamata. In particular, our data show that elemental ratios in chalcopyrite (e.g., Se/In) and, most importantly, pyrite (e.g., Ag/Co and Co/Cu) bear the potential for vectoring towards porphyry mineralization and higher Cu resources.

The impact of a tear in the subducted Indian plate on the Miocene geology of the Himalayan-Tibetan orogen

Abstract The Yadong-Gulu Rift, cutting across the Gangdese belt and Himalayan terranes, is currently associated with a thermal anomaly in the mantle and crustal melting at 15–20 km depth. The rift follows the trace of a tear in the underthrusted Indian continental lithospheric slab recognized by high resolution geophysical methods. The Miocene evolution of a 400-km-wide band following the trace of the tear and the rift, records differences interpreted as indicative of a higher heat flow than its surroundings. In the Gangdese belt, this band is characterized by high-Sr/Y granitic magmatism that lasted 5 m.y. longer than elsewhere and by the highest values of εHf(i) and association with the largest porphyry Cu-Mo deposits in the Gangdese belt. Anomalously young magmatic rocks continue south along the rift in the Tethyan and Higher Himalayas. Here, a 300-km-wide belt includes some of the youngest Miocene Himalayan leucogranites; the only occurrence of mantle-derived mafic enclaves in a leucogranite; young mantle-derived lamprophyre dikes; and the youngest and hottest migmatites in the Higher Himalayas. These migmatites record a history of rapid exhumation contemporaneous with the exhumation of Miocene mafic eclogite blocks, which are unique to this region and which were both heated to >800 °C at ca. 15–13 Ma, followed by isothermal decompression. We suggest that the prominent tear in the Indian lithosphere, sub-parallel to the rift, is the most likely source for these tectono-thermal anomalies since the Miocene.

Fluid inclusion and C-O isotopic constrains on the origin and evolution of ore-forming fluids of the Badaguan Cu-Mo deposit, Inner Mongolia

The Badaguan porphyry Cu–Mo deposit is located in the Derbugan metallogenic belt. Aqueous (W-type), CO2-rich (WC-type), vapor-rich (V-type), and daughter mineral–bearing inclusions (S-type) were recognized in the hydrothermal quartz. Fluid inclusions in the early stage show high homogenization temperatures (247–374 ℃) and high pressures (66–191 MPa), with salinities of 0.95–12.15 wt% NaCl equiv. The presence of anhydrite in veins and phenocrysts suggests high oxygen fugacity conditions. The veins in the Mo- and Cu mineralization stages were formed by immiscible fluids at temperatures of 244–366 ℃ and 183–342 ℃, and pressures of 39–137 MPa and 30–98 MPa, respectively. They yielded salinities of 1.69–10.52 and 0.35–6.85 wt% NaCl equiv, respectively. Homogenization temperatures of fluid inclusions in late stage range from 194 to 269 ℃ with a salinity of 0.6–5.88 wt% NaCl equiv. It is concluded that the ore-forming fluids in the early stage were magmatic in origin, then gradually diluted and cooled by meteoric water. During this process, fluid immiscibility and CO2 release induced by pressure drop and oxygen fugacity decrease resulted in Mo mineralization, while temperature drop was the main trigger for the precipitation of chalcopyrite. Laser-Raman analyses suggest that the fluid inclusions of the Badaguan porphyry Cu-Mo deposit in Inner Mongolia are rich in CO2. Minor CH4 occurs in the Mo- and Cu-mineralization stage, which may be generated during water–rock interaction. The hybrid carbon isotope compositions of the fluid inclusions, mainly representing CO2, show a very depleted δ13CPDB (−21‰ to −28.3‰), which can be explained by the joint influence of ~ 0.5% subducted oceanic sedimentary contamination in the mantle and carbon isotope fractionation induced by 35–80% CO2 degassing. Petrographic observation, previous studies on the geochemical and isotopic characteristics of ore-causative rocks rule out the possibility of contamination of ascending magma with reducing wall rocks. The large variations in δ18Owater (−6.6‰ to +2.4‰) for quartz and calcite suggest the participation of meteoric water during water–rock interaction.

Petrogenesis of the Late Jurassic Cu-Mo mineralization-related Xianyang granite porphyry in the Dehua district, Southeast China: Response to the subduction of paleo-Pacific slab and implication for regional exploration

The Dehua Au-polymetallic ore cluster, as one of the most important area in the Wuyi Au-Cu-Mo metallogenic belt, consists of many large to middle sized epithermal Au deposits and recently discovered porphyry Cu-Mo deposits. We first study the geochronology and geochemistry characteristics of the Cu-Mo mineralization-related Xianyang granite porphyry to constrain its petrogenesis, tectonic setting and metal endowment. LA-ICP-MS zircon U-Pb dating yield a precise age of 157.2 ± 0.8 Ma for the Xianyang granite porphyry, indicating that the granite porphyry was emplaced during the Late Jurassic. The Xianyang granite porphyry was suggested to be generated under continental arc setting, associated with subduction of the paleo-Pacific slab beneath the South China Block. The Xianyang granite porphyry belongs to the high-K calc-alkaline series, with SiO2 of 71.16–72.02 wt% and K2O of 4.28–4.69 wt%. It shows light rare earth element-enriched distribution patterns with (La/Yb)N of = 9.74–13.93, enrichment in large ion lithophile elements, but depletion of high field strength elements, with negative Nb, Ta and Ti anomalies, suggesting an arc magma geochemical affinity. It has lower initial 87Sr/86Sr ratios of 0.7079–0.7086 and relatively higher εNd(t) and εHf(t) values of −8.03 to −7.69 and − 8.86 to −5.48, respectively, than those of basement rocks of the Cathaysia block, suggesting that it was most likely generated by partial melting of the regional ancient crustal materials, with the involvement of asthenosphere mantle-derived materials. The Xianyang granite porphyry has remarkably high zircon Ce4+/Ce3+ values of 119–404 (mean = 245) and EuN/EuN* values of 0.37–0.60 (mean = 0.51), indicating a high oxygen fugacity, which is favor of the formation of the Xianyang porphyry Cu-Mo mineralization. Combining with published research results for regional subvolcanic rocks-related epithermal Au deposits, the porphyry Cu-Mo deposits and epithermal Au deposits in the Dehua ore cluster share similar petrogenetic-metallogenic ages and magma sources in the continental arc setting during the Late Jurassic period. The identification of the coeval porphyry-epithermal Cu-Mo-Au metallogenic system in the Dehua ore cluster highlights the possibility of finding the hidden porphyry Cu-Mo orebodies beneath the discovered epithermal Au deposits.

Geochronology and Geochemistry of Late Paleozoic Volcanic Rocks and Their Relationship With Iron and Molybdenum Deposits in Xilekuduk Area, Northern Margin of Junggar

A large number of intermediate basic volcanic rocks and porphyry Cu-Mo deposits as well as volcanic-hosted magnetite deposit have been recently discovered in the Xilekuduk area. However, no reports concerning petrogenesis and age or their relationship with mineralization have been published to date. The purpose of this study was to make up for the absence of previous studies on Devonian volcanic activities in the area and to confirm the relationship between two stages of volcanic activities and mineralization so as to provide important theoretical basis for mineral exploration. Based on research results of zircon U-Pb geochronology and element geochemistry of volcanic rocks in the area, the ages of dacite, andesite, and stomatal andesite are considered as 375.2 ± 2.9 Ma, 386.5 ± 3.0 Ma, and 317.9 ± 2.9 Ma, respectively, corresponding to the Middle Devonian and Late Carboniferous Period. The Devonian volcanic rocks belong to the high-K calc-alkaline series and island arc volcanic rocks, which are enriched in LREE, strongly enriched in large ion lithophile elements Th, Rb, Ba, and K and relatively depleted in high-field strength elements (HFSEs) Nb, Ta, and Ti. The Carboniferous volcanic rocks are enriched in LREE, as well as the large ion lithophile elements Th, Rb, Ba, and K are strongly enriched, while depleted in the HFSEs Nb, Ta, and Ti; moreover, the contents of TiO2and V are 0.94–0.97% and 178–183×10–6, which are higher than those of island arc basalts. According to mineralogical typomorphic characteristics and geochemical analysis, magnetite mineralization is divided into two phases. The early stratiform magnetite ore MT1 has magmatic characteristics, forming a volcanic rock type magnetite deposit related to Devonian volcanic eruption and sedimentation (375–386 Ma). The magnetite MT2 in the magnetite-quartz vein is considered as hydrothermal genesis, which is a metal mineral in the early metallogenic stage of Carboniferous (317.1 ± 2.9 Ma) volcanic eruption and subvolcanism, and may be related to porphyry molybdenum mineralization. Therefore, the volcanism and Fe-Cu-Mo mineralization in this area is characterized by multistage superimposed mineralization.

Superimposed mineralization in the deformed Yulekenhalasu porphyry Cu-Mo deposit (Northwest China): Rb-Sr geochronology, S isotope, and trace element analysis of chalcopyrite

The Yulekenhalasu porphyry Cu–Mo deposit is located ca. 40 km southwest of Qinghe, in the Chinese Altay-East Junggar section of the Central Asian Orogenic Belt, NW China. The belt preserves multistage tectonic-hydrothermal and porphyry Cu-Mo mineralization events associated with arc to syn- and post-collision environments over 87 m.y. The 359 Ma deformed granitic porphyries are characterized by positive εNd(t) (+0.62 to + 3.77) and (87Sr/86Sr)initial values (0.704304–0.705960), and old crustal model ages of 747 to 1216 Ma, whereas a 272 Ma sample from late chalcopyrite–molybdenite–pyrite–magnetite–feldspar–calcite–gypsum veins yielded (87Sr/86Sr)initial values of 0.704415 to 0.705764, high εNd(t) values (+5.81 to + 5.88) and young crustal model ages (715 to 614 Ma) suggesting an increasingly juvenile mantle source over time. Seven fragments of a single deformed chalcopyrite grain yielded an Rb-Sr isochron age of 358.6 ± 4.8 Ma (2σ, MSWD = 1.8), which is consistent with the 360 Ma recrystallized zircon grains in the deformed host granitic porphyries. Eight fragments of chalcopyrite from the chalcopyrite–molybdenite–pyrite–magnetite–feldspar–calcite–gypsum veins formed along cleavage planes yielded a younger Rb-Sr isochron age of 272.2 ± 2.6 Ma (2σ, MSWD = 1.8). The younger age is interpreted as the lower age limit for the Mo and Cu mineralization in the post-collisional stage. The heterogeneous initial Sr isotopic compositions of chalcopyrite in the Yulekenhalasu deposit are likely the result of phyllosilicate inclusions. Disseminated chalcopyrite crystals in the granitic porphyry have different trace elemental contents than chalcopyrite in the deformed granitic porphyry and late chalcopyrite veins. Our Rb-Sr and trace element data for chalcopyrite grains constrain the age and geochemistry of multistage mineralization in porphyry Cu-Mo deposits. In-situ S isotope data of chalcopyrite from the deformed granite porphyries and chalcopyrite-feldspar-quartz-muscovite veins display a similar mantle origin. The 272 Ma mineralization event at Yulekenhalasu is coeval with the formation age of the Cu-Ni-(PGE) sulfide deposit in the Chinese Altay, indicating that hydrothermal mineralization like that in porphyry deposits can form proximal to ultramafic–mafic rocks and potentially may have a genetic relationship with mantle-derived Cu-Ni-(PGE) sulfide deposits.

Difference in the nature of ore-forming magma between the Mesozoic porphyry Cu-Mo and Mo deposits in NE China: Records from apatite and zircon geochemistry

Porphyry Cu-Mo and Mo deposits are the most important source of Mo in the world, but factors controlling their difference remain enigmatic. In recent years, many Mesozoic porphyry Cu-Mo and Mo deposits have been discovered in NE China, which provides a good opportunity to explore the difference between the Cu-Mo and Mo mineralization. In this region, porphyry Cu-Mo deposits (Wunugetushan, Jinchanggou) are distributed along the subduction zone, while the porphyry Mo deposits (Luming, Fu'anpu, Daheishan) are far away from the subduction zone. On the basis of whole rock geochemical studies, we present a comprehensive investigation on the apatite and zircon from Mesozoic typical porphyry Cu-Mo deposits and Mo deposits, in order to reveal the nature of parent magma constraints on Cu-Mo and Mo mineralization. Whole-rock geochemistry, in-situ apatite Sr-Nd and zircon Hf isotopic compositions from these granites in porphyry Cu-Mo and Mo deposits indicate that these granites originated from a juvenile crustal source. Apatites from the porphyry Cu-Mo mineralized granites show relatively high Cl and low F contents, accompanied by enrichment of fluid-mobile elements Ba and Sr, indicating that the magmatic source of porphyry Cu-Mo deposits were modified by subducted slab-derived fluids. In comparison, apatites from the porphyry Mo mineralized granites have high F and low Cl contents with correspondingly high F/Cl ratios, suggesting that these granites mainly formed in juvenile crustal dehydration self-metasomatism under the intra-continental environment. Additionally, apatites from porphyry Cu-Mo mineralized granites have higher OH contents than those from porphyry Mo mineralized granites, indicating that the original melt of porphyry Cu-Mo system was more hydrous, consistent with their higher (Ce/Nd)/Y and lower Dy/Yb ratios of zircon. It is here proposed that the formation of porphyry Cu-Mo deposits in NE China are related to partial melting of the juvenile crust, which metasomatized by slab-derived Cl-enriched fluids with carry significant amounts of Cu, whereas the porphyry Mo deposits are related to partial melting of juvenile crustal material with released F-enriched fluids by the dehydration of hydrous minerals.

Fluid evolution in the Beidabate porphyry Cu-Mo deposit, Xinjiang, northwest China: Evidence from fluid inclusions and H-O-C-S isotopes

• A fluid evolution model for Beidabate deposit is presented. • The model relies on fluid phase separation. • The precipitation mechanism for Mo and Cu is proposed. The Beidabate deposit is a porphyry Cu-Mo deposit located in the West Tianshan Orogenic Belt , Xinjiang Uygur Autonomous Region. The fluid evolution path and Cu-Mo mineralization mechanism remain obscured by multiple hydrothermal pulses. Systematic fluid inclusion and H-O-C-S isotope analyses were performed on five identifiable mineralization stages. Variations in fluid composition, temperature, and pressure record the fluid evolution path: (1) During the formation of barren quartz veins (stage I), fluid inclusions were trapped under single- to two-phase transitional conditions, as evidenced by the presence of intermediate-density inclusions as well as coexisting daughter mineral-bearing inclusions and vapor-rich inclusions (boiling FIAs). Fluid phase separation occurred at temperatures of 387–412 °C and pressures of 180–300 bar. (2) Fluid inclusions in K-feldspar-quartz veins (stage II) and molybdenite-quartz veins (stage III) were trapped under two-phase conditions. Boiling FIAs were also recognized, with homogenization temperatures of 306–368 °C and entrapment pressures of 80–200 bar. Fluid boiling is the main precipitation mechanism of molybdenite . (3) Fluid inclusions in pyrite-chalcopyrite-quartz veins (stage IV) and fluorite-chalcopyrite veins (stage V) are predominantly liquid-rich and CO 2 -bearing inclusions, which represent extraneous fluids. These inclusions homogenized at temperatures of 192° to 285 °C, and minimum entrapment pressures of 40–50 bar. Fluid mixing is the main precipitation mechanism of chalcopyrite . H-O-C-S isotope data (δ 18 O = 3.2 to 15.2‰, δD = −103.6 to −75.1‰, δ 13 C = −24.2 to −9.7‰ and δ 34 S = 4.6 to 7.0‰) indicate that the ore-forming fluids have a predominantly magmatic signature with subsequent dilution by late meteoric water and intense water–rock interaction. We established a genetic model of the Beidabate porphyry Cu-Mo deposit with the aim of providing insight into prospecting at a regional scale.

Significance of chlorite hyperspectral and geochemical characteristics in exploration: A case study of the giant Qulong porphyry Cu-Mo deposit in collisional orogen, Southern Tibet

Abstract The genetic mechanism and exploration model for porphyry deposits in subduction zones has been comprehensively and systematically investigated; in contrast, our understanding for porphyry mineralization in collisional orogeny is limited. Qulong porphyry Cu-Mo deposit, a typical porphyry Cu deposit (PCD) developed in the collisional setting, was chosen as the subject of this study. The study is mainly focused on interpretation of short-wave infrared (SWIR) spectroscopy combined with mineral geochemistry of chlorite from Qulong deposit to guide exploration in future. Hydrothermal alteration in Qulong mineralization system can be divided into three zones, which are the inner potassic alteration zone, the outside propylitic alteration zone and phyllic alteration. Phyllic alteration can be intensively superimposed on the early potassic and prophylitic alteration zones. Chlorite is widely distributed in both of the propylitic and phyllic zones. Four types of chlorite were observed in Qulong deposit, including three stages of vein-related chlorite (Chl-I, Chl-II, Chl-III) and one type of disseminated chlorite (Chl-D). Mineral assemblage of Chl-I stage includes chlorite–anhydrite–pyrite. Minerals in Chl-II stage consist of chlorite–epidote–pyrite–chalcopyrite. Mineral assemblage of Chl-III stage is composed of chlorite–sericite–quartz–chalcopyrite, which is later than both Chl-I and Chl-II. Chl-D was developed mainly by alteration of primary biotite phenocryst. Chl-I, Chl-II and Chl-D were formed along with the propylitic alteration; however, Chl-III is from the phyllic alteration. Chl-II and Chl-III are both closely related with Cu mineralization. The major element compositions of chlorite show a regular variation of Mg# with fluid evolution. Transition from shorter wavelength chlorite (Fe feature around 2250 nm) to longer wavelength goes with the decrease of Mg#, except for Chl-D. In summary, chlorite associated with Cu mineralization in Qulong is mainly occurred in veins and has low Mg# ratios and longer wavelength. Such chlorite is the indicator for Cu mineralization and should be the target in future exploration. In addition to chlorite, sericite in Qulong also shows systematic change from early-stage phengite to late-stage muscovite. In combination of mineral geochemistry and thermodynamic modelling, we suggest that ore-forming fluid gradually evolved to be more acidic with higher silica activity over time.

Fluid-rock reactions of the Triassic Taiyangshan porphyry Cu-Mo deposit (West Qinling, China) constrained by QEMSCAN and iron isotope

The multiphase hydrothermal superposition phenomena on porphyry deposits, the mineral complexity and characteristics of the alteration-associated assemblages limit a further determination for the magmatic-hydrothermal evolution in porphyry deposits. The Taiyangshan porphyry Cu-Mo deposit in the northern margin of the Triassic West Qinling Orogenic Belt exhibits a multi-stage, alteration-related quartz sulfide veins that recorded element migration processes during fluid-rock reactions. In this study, we investigated hydrothermal veins in the Taiyangshan deposit focusing on vein compositions and structures as well as the evolution of ore formation, using quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) and iron isotope analyses. The formation of the early K-feldspar-biotite-quartz-magnetite-apatite veins is closely associated with the early potassic alteration, and during the fluid-rock reactions, Si, S, Fe, and K migrated in, while Mg, Ca and Na migrated out. K-feldspar-chlorite-pyrite-chalcopyrite-quartz veins correlated to the propylitic alteration, dominantly caused the migration of Si, Fe, S, Ca Mg, Al and K. Quartz-sericite-pyrite veins corresponding to the phyllic alteration processes that occurred in a relatively late stage, during the fluid-rock reactions of which, Si, Fe, S, and K migrated into the system. The δ56Fe whole-rock values of altered porphyries range from 0.08‰ to 0.31‰, and δ56Fe values of pyrite from quartz veins range from 0.30‰ to 0.57‰. Iron isotope compositions of both pyrites of the ore-bearing wall rocks and the quartz-sulfide veins of the Taiyangshan Cu-Mo deposit are generally uniform, which indicate the same source origin between the ore-bearing porphyry and the iron isotope compositions of the metal sulfide in the quartz veins, and additionally highlight that the ore-forming source is closely related to the ore-bearing porphyry. Magnetite precipitated in the early stage of potassic alteration, resulting in the enrichment of the light Fe isotope in the early fluids. Crystallization and precipitation of pyrite mainly occurred during processes of propylitic and phyllic alteration, leading to an absorption of the light Fe isotope, and elsewhere, an enrichment of the heavy Fe isotope in the fluids. During the fluid-rock reactions of propylitic and phyllic alteration, a large amount of S migrated into the veins, thereby promoting the fractionation of Fe isotope. Moreover, the development of the ore-forming fluids enriched with heavy Fe isotope from early potassic- to late phyllic alteration, are indicative of isotopic progressions from the early lithostatic pressure to the late hydrostatic pressure. Our research on the Taiyangshan Cu-Mo porphyry deposit helps to explain the evolutionary processes of the magmatic–hydrothermal system, and improves our understanding of the porphyry metallogenic evolution model.

The key role of volatile-rich magma replenishment in the formation of porphyry Cu-Mo deposits: A case study of Gangjiang porphyry Cu-Mo deposit, Tibet

西藏冈底斯带中段的岗讲斑岩铜-钼矿床发育多期次侵入体，而成矿作用主要与其中一期岩体（流纹英安斑岩）密切相关。为探究其原因，本文对岗讲斑岩铜-钼矿床中发育的各期次侵入体进行了全岩主、微量元素分析，并重点研究各期次侵入体内部新鲜斑晶（黑云母、斜长石）和副矿物（锆石、磷灰石）的化学成分和结构特征。结果表明，矿区各期次侵入岩均属于高钾钙碱性系列，具有相近的锆石饱和温度，都来自较为氧化的岩浆。此外，相比其他期次侵入岩，主成矿期的流纹英安斑岩中的磷灰石具有较高的SO3、Cl含量，较低的F含量；黑云母含有较高的Cl含量和较低的F含量；同时，斜长石发育反环带。这些证据表明，在主成矿期岩浆就位之前，存在富S、Cl的偏基性岩浆注入了深部岩浆房，并发生岩浆混合作用，这不仅导致了主成矿期斑岩体的就位，同时还诱发流体出溶进入浅部岩浆房，并最终形成岗讲斑岩铜-钼矿床。

Mesozoic Metallogenesis of Peru: A Reality Check on Geodynamic Models

Abstract The Andean Cordillera is generally regarded as the product of easterly subduction of oceanic lithosphere below South America since the Late Triassic, but recent syntheses have challenged this paradigm. In one model, W-dipping oceanic subduction pulls the continent west until it collides with a ribbon continent that now forms the coastal region and Western Cordillera of the Peruvian Andes. A second model involves westerly oceanic subduction until 120 to 100 Ma, without the involvement of a ribbon continent, to explain deep, subducted slabs revealed by mantle tomographic images. Both assume that “Andean-style” E-dipping subduction did not exist during the Jurassic and Early Cretaceous. Another model, also involving mantle tomography, assumes that a back-arc basin opened inboard of the trench between 145 and 100 Ma, displacing the E-dipping subduction zone offshore without changing its polarity. This article examines the implications of these hypotheses for southern Peruvian metallogenesis during the Mesozoic, when marginal basins opened and closed and were thrust eastward and then were intruded, between 110 and ~50 Ma, by a linear belt of multiple plutons known as the Coastal Batholith. The earliest mineralization in southern Peru is located on the coast and comprises major iron oxide and minor porphyry copper deposits emplaced between 180 and 110 Ma. This was followed by Cu-rich iron oxide copper-gold deposits and a large Zn-rich volcanogenic massive sulfide (VMS) deposit between 115 and 95 Ma, then minor porphyry Cu deposits at ~80 Ma. A second episode of localized VMS mineralization followed at 70 to 68 Ma, then a group of at least five giant porphyry Cu-Mo deposits in southernmost Peru formed between 62 and 53 Ma. The conventional model of Andean-style subduction, which explains many features of Mesozoic Andean metallogenesis in terms of changing plate vectors and velocities, is a poor fit with mantle tomographic anomalies that are thought to record the paleopositions of ancient trenches. A ribbon-continent model requires some plutons of the Coastal Batholith to have been separated from others by an ocean basin. West-dipping oceanic subduction does not account for Jurassic mineralization and magmatism in southern Peru. A model involving a back-arc basin that opened inboard of the existing trench, forcing E-dipping subduction to retreat offshore between 145 and 100 Ma, seems to best explain the metallogenic and tomographic data.

Distribution characteristics and influencing factors of rhenium concentrations in molybdenite from the porphyry Cu-systems: A review

金属铼（Re）是支撑航空航天等高科技产业高质量发展的重要原材料，具不可替代性。研究表明，世界上绝大部分的Re都赋存在斑岩型矿床的辉钼矿之中，且Re含量在矿床、矿石、矿物颗粒等不同尺度上均存在较大差异，但目前学术界对导致这些差异的影响因素尚不清楚。本文通过对全球斑岩型Cu（Mo）、Mo（Cu）矿床中Mo品位、辉钼矿的微量元素组成和Re-Os年龄、成矿岩体的化学组成、Sr-Nd同位素等数据的汇总，深入探讨了影响该类矿床辉钼矿中Re含量变化的主要因素。结果显示，Re含量与矿床中钼的平均品位呈负相关，地幔物质的加入可能是形成高Re辉钼矿的基础。本研究证实，辉钼矿Re含量与其成矿时代不具耦合关系，并且Re的含量与辉钼矿沉淀的位置、以及辉钼矿多型之间亦无明显相关性，而可能与成矿岩体的成分、岩浆分异程度、成矿流体的性质、热液蚀变及表生作用过程有关。;As one of key metals, rhenium (Re) is extensively used in high-tech fields such as aerospace due to its refractory geochemical properties, which is irreplaceable. Previous studies have shown that most of Re in the world is concentrated in molybdenite of porphyry Cu-Mo deposits, but Re concentrations vary significantly on the scale of ore deposits, samples and even individual molybdenite particles. At present, understanding of such difference is still unclear. Based on the data of molybdenum grades, trace elements contents of molybdenite, molybdenite Re-Os ages, lithogeochemical and Sr-Nd isotopic compositions of porphyry Cu(Mo) and Mo(Cu) deposits in the world, key factors of affecting Re concentrations in molybdenite from porphyry deposits are discussed. The results show that Re concentrations are negatively correlated with the average molybdenum grades, and mantle-derived component input may be in favor of high Re molybdenite formation. This study confirmed that there were no direct relationships between Re concentrations of molybdenite and metallogenic ages of porphyry deposits, molybdenite precipitation locations, and molybdenite polytypes. In contrast, rhenium concentrations in molybdenite may be related to the compositions of ore-forming rocks, magmatic differentiation degree, nature of ore-forming fluids, hydrothermal alteration and supergenesis.

Evolution of Multistage Hydrothermal Fluids in the Luoboling Porphyry Cu-Mo Deposit, Zijinshan Ore Field, Fujian Province, China: Insights from LA-ICP-MS Analyses of Fluid Inclusions

Abstract The Luoboling Cu-Mo deposit, with 1.4 million tons (Mt) Cu and 0.11 Mt Mo, is the largest porphyry deposit in the Zijinshan district of southeast China. Mineralization at Luoboling is divided into premineralization, synmineralization, and late-mineralization stages. Consistent Cs/(Na + K) ratios in fluid inclusions suggest that the mineralizing fluids originated from a common source—the Luoboling granodiorite porphyry. The absence of initial supercritical fluid inclusions and abundant coexisting vapor and brine fluid inclusions imply that the fluids exsolved at low-pressure two-phase conditions, with temperatures of 250° to 600°C and salinities of 30 to 60 wt % NaCl equiv (brines) and <10 wt % NaCl equiv (vapors). The deposit formed at ~120 to 800 bar, corresponding to the depths of ~1.2 to 3.2 km (assuming a transition from lithostatic to hydrostatic load). Metals such as Mo (up to 77 ppm), Pb (up to 8,800 ppm), Zn (up to 13,000 ppm), and Ag (up to 130 ppm) migrated mainly in brines. Although vapor inclusions have high concentrations of Cu (up to 20,000 ppm), hypersaline fluid was the major medium for Cu transport and precipitation. The successive precipitation of Mo and Cu occurred when fluids cooled to ~500°C and ~350° to 450°C, respectively. The late-stage quartz-pyrite veins with phyllic alteration were formed by Cu-rich magmatic hydrothermal fluids. The Zijinshan epithermal Cu-Au deposit and the Luoboling porphyry Cu-Mo deposit originated from independent hydrothermal systems. Nonetheless, the increasing trends of Pb, Zn, and Ag concentrations in different stage inclusions from Luoboling imply potential for distal Pb-Zn-Ag mineralization.