Granite Porphyry Research Articles

Genesis and Tectonic Implications of Early Cretaceous Granites in the Haobugao Area, Southern Great Xing’an Range: Insights from Zircon U–Pb Geochronology, Hf Isotopic Composition, and Petrochemistry

In the Huanggangliang–Ganzhuermiao metallogenic belt in the southern Great Xing’an Range, the Haobugao Pb‒Zn deposit is the most widespread skarn-type polymetallic deposit. The observed mineralization processes in this area are closely associated with both magmatic and tectonic activity. The zircon U‒Pb ages of two granitoid phases are 134.0 ± 0.6 Ma and 133.4 ± 0.9 Ma (Early Cretaceous). High SiO2 content (average mass fractions of 77.98 wt.% and 73.25 wt.%), high alkalinity (average mass fractions of 6.19 wt.% and 8.78 wt.%), and low CaO levels (average mass fractions of 0.16 wt.% and 0.12 wt.%) are characteristic of these rocks. They are also enriched in high-field-strength elements (HFSEs) (Th, U, Ta, Zr, Hf, etc.) and depleted in large ion lithophile elements (LILEs) (Ba, Sr, etc.). Furthermore, the Nb/Ta ratios (7.80~8.82, 10.00~10.83) point to a crustal origin of the magma. The zircon Hf isotopic compositions suggest that the melting of young crust derived from Meso-Neoproterozoic and Neoproterozoic depleted mantle gave rise to the magma in these granite porphyries. These rocks formed in an extensional environment driven by the subduction and retreat of the Paleo-Pacific plate during the Early Cretaceous.

Formation and degradation of a porphyry occurrence: The oligocene Khatoon-Abad porphyry Mo-Cu system, NW Iran

This study investigates the temporal relationships between mineralization and magmatism in the Khatoon-Abad porphyry Mo-Cu prospect (Urumieh-Dokhtar Magmatic Arc, NW Iran). Integrated zircon U-Pb and molybdenite Re-Os dating document a prolonged stationary magmatism, spanning ∼ 45 Myr (from ∼ 66 to ∼ 21 Ma; Paleocene-Early Miocene). Three main Oligocene ore-bearing granitic intrusions and an early Miocene barren dyke swarm are documented, with the main mineralization formed at ∼ 27 Ma, as attested by the molybdenite Re-Os age of 26.75 ± 0.14 Ma and the zircon U-Pb age 26.93 ± 0.30 Ma from the host granodiorite porphyry. Despite having similar geochemical fingerprints, including an adakitic signature and having REE patterns similar to productive magmas, the subsequent Oligocene granite bodies (∼26.0–25.7 Ma) yielded lower Mo-Cu enrichments and the early Miocene rhyodacite dykes (∼21 Ma) are barren. This evidence demonstrates that the efficiency of mineralization has been reduced by changes in the physiochemical conditions of magmatic-hydrothermal systems over time. We suggest that a perturbed geothermal gradient during later Oligocene granite (at ∼ 26 Ma) caused slow cooling/degassing of the melts, and hence determined an inefficient mineralization environment. We also infer that during the latest granite porphyry pulse (∼25.7 Ma), the structurally-controlled emplacement at shallower levels resulted in rapid melt cooling along with more meteoric water mixing, eventually minor potassic but vast phyllic alterations, and hence, causing a dispersed mineralization rather than a focused fluid flow. Therefore, the later Oligocene and early Miocene magmatic pulses degraded the early mineralization. The results of this study emphasize that a consistent magma supply into the chamber followed by a rapid magma-fluid flux to the mineralization site are needed for efficient mineralization in collisional settings. Otherwise multiple mineralization pathways and sites would result in low-grade ore bodies.

Genetic relationship between W mineralization and granitic intrusion in Nanling Region, South China: Constraints from zircon and cassiterite u-pb age from new drill holes in Shangping deposit

The Nanling metallogenic belt is known for the widely development of typical quartz vein type W deposit. These quartz veins that contain wolframite are frequently located in close proximity to granitic intrusions. The genetic relationship between tungsten mineralization and the associated granitic rocks is still a subject of controversy. The Shangping deposit stands out as a historically significant W deposit with a quartz vein type in the region of Nanling. However, the specific time that W mineralization occurred remains enigmatic. Granitic intrusions are absent from the mine and only granite porphyry dike is exposed, so the link between tungsten mineralization and magmatic activity remains unclear. Fortunately, in recent years, a concealed granite intrusive has been exposed in drill holes in the southeastern of the Shangping W deposit. To comprehensively address the connection between granitic magma activity and W mineralization, it is vital to make up a relative deficiency of geochronological information on granite and ore mineral. Here, in order to get the first direct age constraints on the origin of the Shangping W deposit, we use a combination of different techniques, incorporating the Hf isotope geochemistry of zirconium and cassiterite U-Pb assessment using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Based on these robust data, we tentatively evaluated the connection between W mineralization and granitic intrusion.For the granite porphyry, the majority of representative U-Pb zircon assays establish a206Pb/238U age of 150.2 ± 0.5 Ma. An inferred emplacement age of ca. 151 Ma for the concealed granite in Kengweiwo is supported by a U-Pb isochron age from zircon. Combined with Hf isotopic characterization, it illuminates the mineralization potential of the Kengweiwo concealed granite. Cassiterite grains from hydrothermal quartz vein are subhedral to anhedral and have a lower intercept 206Pb/238U age of 153.9 ± 1.0 Ma. For the Shangping W deposit, all of these new geochronological dates provide well-constrained mineralization ages of 150–154 Ma. The dates of the concealed granite in the Kengweiwo area and the tungsten mineralization in the Shangping area are extremely concordant, indicating that they occurred roughly concurrently. The vein type tungsten mineralization in Shangping deposit may has a genetic link with crystallization of uncovered granite present at depth, which requires further investigation. These results emphasize the significance and potential of concealed granitic intrusion to host disseminated W mineralization in the deep part of Shangping deposit.

Water content drives distinct evolution trajectory of Early Cretaceous granitoids in inland and coastal southeast China

Water plays a crucial role in determining the crystallization sequence of magma, which subsequently influences the chemical compositions of magmatic rocks across different tectonic settings. In this study, we compared the evolutionary features of granitic rocks along the coast and inland areas of southeast China, aiming to identify the key factors influencing their evolution. Our work indicates that multiple granitic intrusions formed between 126 and 142 Ma in the coastal region of southeastern China, which is consistent with the formation ages of large-scale granitoids in the inland Gan-Hang Belt. Isotopic characteristics suggest that the granitic rocks in southern Fujian originated from the melting of juvenile crust, while those in northern Fujian and eastern Zhejiang were formed from the partial melting of ancient crustal rocks, incorporating mafic magma evolved from the mantle. Most of the granitoids from the coastal region of southeastern China exhibit low zircon saturation temperatures (680–800 °C) and Zr/Sr ratios (<1), suggesting their origin from a cold, wet magma reservoir. The porphyritic quartz diorite and porphyritic monzogranite represent the residual cumulate rocks of this hydrous magma reservoir, whereas the granitic porphyry and high-silica equigranular alkali feldspar granite evolved from the felsic melts extracted from the same reservoir. In contrast, most of the Early Cretaceous granitoids in the Gan-Hang Belt, located in the inland areas of southeast China, display high zircon saturation temperatures (800–900 °C) and Zr/Sr ratios (>1), indicating their origin from hot, water-poor magma reservoirs. The porphyritic granites in this region represent residual cumulate rocks formed in water-poor magma reservoirs, whereas the high-silica equigranular granites evolved from hot felsic melts extracted from similar magma reservoirs. In the Early Cretaceous, the coastal region of southeastern China was closer to the Late Mesozoic paleo-Pacific subduction zone, where crystal-melt segregation within cold, wet magma reservoirs predominantly influenced magma evolution. Conversely, the granitoids in the Gan-Hang Belt in the inland region, located farther from the Late Mesozoic paleo-Pacific subduction zone, were associated with a rift tectonic setting and formed through crystal-melt segregation within hot, water-poor magma reservoirs. Our study underscores the critical role of water content in magma reservoirs in shaping the chemical composition of granitic rocks through crystal-melt segregation, thereby deepening our understanding of crustal formation processes across diverse tectonic environments.

Arc-shaped faults of the Golden Valley gold field of the Midlands greenstone belt in Zimbabwe and their role in localization of the ore mineralization

A detailed analysis of the geological and structural position of gold and tungsten deposits in the Golden Valley ore field of the Midlands greenstone belt has demonstrated that most of the gold deposits are controlled by arc-shaped faults that taken together form a semicircular structure with dimensions of 9×11 km. In addition, these arc-shaped faults apparently control the distribution of dikes of porphyry granites, that are associated with gold ore veins. Quartz-scheelite and gold-quartz-scheelite veins together form a second, less distinct, semicircular structure comparable in size to the first one. The highlighted structures were formed around isometric Late Archean granodiorite massifs, Lion Hill and Whitewaters, respectively, and are partially overlapped in space. The magnetic fi ld, also, reveals one additional arc-shaped fault and a series of linear faults. This arc-shaped fault, in conjunction with its associated branching veins of the Golden Valley and Patchway deposits, represents the so-called “horsetail” structure that is characteristic for gold deposits. This fault that is the most favorable structure for localization of gold ore veins, as well as the proposed junctions of arc-shaped and linear faults of radial and northwestern orientations, are considered as the most promising areas where geological prospecting is recommended.

Magmatic Evolution and Nb-Ta Enrichment of Early Jurassic Granitic Porphyry from the Shangxiahu Nb-Ta Deposit of the Nanling Range

Magmatic Evolution and Nb-Ta Enrichment of Early Jurassic Granitic Porphyry from the Shangxiahu Nb-Ta Deposit of the Nanling Range

Genesis of the Haopinggou breccia-hosted Au deposit, western Henan Province, China

Breccia-hosted Au deposits within the North China Craton (NCC) exhibit a complex genesis, with some breccias being genetically linked to Au mineralization and others unrelated. Understanding the origin of these breccias is crucial for elucidating the genesis of associated ore deposits and guiding exploration strategies. The Haopinggou deposit in the Xiong’ershan district, on the southern margin of the NCC, comprises quartz-carbonate vein-hosted Ag–Pb–Zn–Au deposits and related breccia pipe in metamorphic rocks of the late Archean to early Paleoproterozoic Taihua Group. The origin of the Haopinggou breccia is crucial to understand the Xiayu Ag-Pb-Zn-Au mineralization (5640 t Ag). In this study, we evaluate the genetic links between breccia and Ag-Pb-Zn-Au mineralization, with new insights obtained from the Haopinggou deposit characteristics, breccia characteristics, breccia-hosted Au mineralization, and isotopic data, which refine our understanding of Haopinggou Ag-Pb-Zn-Au hydrothermal systems and exploration models in discordant breccia pipes. Recent underground tunnel surveys and drill-core logging reveal a close spatial link between the breccia and hidden granite porphyry. Juvenile magmatic clasts (granite porphyry) and cement (K-feldspar and quartz crystallized from granite porphyry) are present in the breccia pipe above a granite porphyry apophysis, indicating that the breccia was formed by phreatomagmatic brecciation caused by emplacement of the granite porphyry. Fluidization at the cm- to 100-m-scale reveals that the movement direction of clasts inside the breccia pipe was from northwest to southeast after crypto-explosion, creating a northwest-trending breccia zone. Anhedral monazite (131.2 ± 7.6 Ma) encapsulated in pyrite from the breccia constrains the upper limit of brecciation. The δ34S values of pyrite in rock powder and hydrothermal cements range from 3.8 ‰ to 5.3 ‰ (mean: 4.8 ‰) and 2.7 ‰ to 7.5 ‰ (mean: 5.2 ‰), respectively, with δ34S-sphalerite in hydrothermal cement ranging from 5.7 ‰ to 6.1 ‰ (mean: 5.9 ‰) and δ34S-chalcopyrite ranging from − 0.9 ‰ to 5.6 ‰ (mean: 2.9 ‰). The S isotope characteristics of vein-hosted and breccia-hosted mineralization zones are consistent, with complete alignment of the sulfide assemblages and alteration features. These pieces of evidence collectively indicate that both vein- and breccia-hosted mineralization zones are products of magmatic activity. The metallogenic model for the Haopinggou breccia pipe underscores its unique formation mechanism, driven by pre-existing northwest-striking structural weaknesses and fluidization, indicative of a predominant northwest–southeast clast movement, and suggesting the potential for deep-seated porphyry-type Au mineralization.

Ages, petrogenesis and metallogenesis implications of the Miocene adakite-like igneous rocks in the Beimulang porphyry Cu Deposit, southern Tibet

Understanding the petrogenesis of Miocene adakite-like igneous rocks is crucial for unraveling the formation processes of post-collision porphyry copper deposits within the Gangdese orogenic belt. This study focuses on the mineralogical, geochronological, and geochemical characteristics of the Beimulang Miocene adakite-like igneous rock series, with particular emphasis on two types of diorite porphyry (DP1 and DP2), to constrain their petrogenesis. Zircon U-Pb dating indicates that the monzogranite (MG), monzogranite porphyry (MGP), DP1, DP2 and granite porphyry (GP) were emplaced at 14.8 ± 0.1 Ma, 14.6 ± 0.1 Ma, 14.6 ± 0.1 Ma, 13.2 ± 0.1 Ma and 12.5 ± 0.1 Ma, respectively. The major element compositions of the Beimulang Miocene intrusions exhibit a differentiation trend. The Sr-Nd isotopic compositions of the MG, MGP, and DP1 align with the mixing line between the juvenile lower crust and the potassic lamprophyres. Conversely, the Sr-Nd isotopic compositions of DP2 and GP fall precisely on the Sr-Nd mixing line between DP1 and the ultrapotassic lamprophyres. Considering the reverse zoning of plagioclase in the DP1 and presence of high-Mg phlogopite in the DP2, we suggest that the Miocene magmatic series at Beimulang likely derived from the mixing of partial melts of Gangdese juvenile lower crust and mantle-derived potassic-ultrapotassic magmas. The increase in Th/Yb ratios from DP1, MG, MGP to DP2 and GP suggests that the mantle metasomatism material may have evolved from slab-derived fluids to melts derived from Indian crustal sediments. The magmatic water content and oxidation calculated from zircon trace elements, are nearly identical among the ore-causative MG and MGP, and the barren GP. However, the decrease in V/Sc ratios from the MG and MGP to GP indicates that magnetite-driven magma sulfide saturation leads to the depletion of chalcophile elements, significantly reducing the Cu mineralization potential of the GP. We suggest that the higher degree of magmatic evolution leads to the barren nature of Beimulang granite porphyry.

VENDIAN-CAMBRIAN SEDIMENTARY PROVENANCE OF THE UPPER KALAR DEPRESSION (ALDAN SHIELD) ACCORDING TO GEOCHEMICAL DATA

There are presented the results of geochemical studies of the Vendian-Cambrian terrigenous rocks in the Upper Kalar depression– sandstones of the Silimkun formation, exposed in the floodplain of the Kilcheris River (left tributary of the China River), in the upper reaches of the Kemen River. The rocks are enriched in Sc, Cr, Nb, V, Co, Ni, as well as in Mo and heavy rare earth elements. This study demonstrates a rare pairwise correlation between Mo and Cr. A strong positive correlation of P with Nb, Ti and Fe is indicative of P sorption phenomena in alteration products of titanium minerals (e.g. leucoxene). It has been found that the sandstones of the Silimkun Formation were formed as a result of the destruction of granitoids of the Kalar massif – presumably granite porphyries and fine-grained porphyritic biotite granites. The influence of the gabbro-norites of the Chiney complex, enriched in trace elements commonly found in rocks, is less pronounced.

New Geochemical and Geochronological Constraints on the Genesis of the Imourkhssen Cu±Mo±Au±Ag Porphyry Deposit (Ouzellagh-Siroua Salient, Anti-Atlas, Morocco): Geodynamic and Metallogenic Implications

The Imourkhssen porphyry Cu±Mo±Au±Ag deposit is located at the Ouzellagh-Siroua Salient (OSS) straddling the boundary between the central Anti-Atlas and the central High Atlas. It is characterized by a typical porphyry-style mineralization. The volcanic rocks are intruded by numerous magmatic rocks of the Ouarzazate Group (580–539 Ma), referred to as the Late Ediacaran magmatic suites (LEMS). Of these, the Askaoun, Imourkhssen, and Imourgane granites are the most significant as they are related to the porphyry mineralization. The entire set is intruded by the Zaghar mafic dyke swarms. Zircon U-Pb dating of the Imourkhssen granite and the ore-bearing granite porphyry shows that these intrusive rocks were emplaced at 558 ± 1 and 550 ± 2 Ma, respectively. Moreover, the whole-rock major and trace element geochemistry reveal a high-K calc-alkaline I-type composition, consistent with an emplacement in a post-collisional setting under a trans-tensional tectonic regime. Ore bodies are hosted by the Askaoun granodiorite as well as the Imourgane granite. The mineralization occurs as fine-grained dissemination and infills of hydrothermally altered NNE–SSW to N–S trending veins and veinlets. Ore-related hydrothermal alteration consists of potassic, chlorite-sericite, serecitic, and propylitic mineral assemblages along with pervasive silicification and pyritization, providing a porphyry-style alteration pattern. The ore periods comprise supergene and magmatic-hydrothermal periods. The latter includes primary dissemination and secondary NNE–SSW to N–S ore-bearing system stages. The occurrence of molybdenite is either restricted to the potassic and chlorite-sericite alteration zones of the ore-bearing granite as fine disseminations or alternatively as veinlet infills within the propylitic halos. The molybdenite occurrences along with pyrite, chalcopyrite, galena, and tennantite dissemination are assigned to the primary ore stage, while the NNE–SSW to N–S ore-bearing system is related to the secondary ore stage. It consists of pyrite, chalcopyrite, bornite, covellite, diagenite, sphalerite, hematite, galena, gold, and chenguodaite. The predominance of cockade and crack-and-seal textures suggest multiple episodes of ore-forming fluid circulations under epithermal conditions. The supergene stage is achieved by subordinate malachite, azurite, barite, hematite, epsomite, and chrysocolla. From the descriptions above, we argue that the Imourkhssen Cu±Mo±Au±Ag mineralization shares many mineralogical and paragenetic attributes of porphyry-copper deposits.

In-situ geochemical and isotopic analyses of multiple pyrite generations: Insights for the giant Beiya Au polymetallic ore genesis in southwestern China

The Beiya giant Au polymetallic deposit is located in the Sanjiang Tethyan Orogen, northwestern Yunnan (SW China). The ores occur as disseminations or veinlets in granite porphyry. To unravel the ore genesis at Beiya, we analyzed the ore-related sulfide trace elements and sulfur isotopes. Py-1 is mainly euhedral-subhedral medium-/coarse-grained (size: > 100 μm), with relatively smooth surface and some pores. Py-2 is mostly coarse grained (size: 50–200 μm), with well-developed pores and inclusions. The pyrite is usually Co-Cu rich and V-Ti-Sb poor, resembling typical magmatic-hydrothermal pyrite. In addition, the Co/Ni ratios decrease from pyrite-1 (Py-1) to pyrite-2b (Py-2b), suggesting that their chemical compositions are controlled by magma fractionation. We found that Co, Ni, As, and Se occurred as solid solution in the pyrite lattice, while Pb, Bi, Ag, and Mn occurred mainly in inclusions in the pyrite. Pb and Bi display good positive correlation, suggesting that they occurred as inclusions or nano-particles in pyrite lattice. The pyrite samples have sulfur isotope value (δ34S) of 0.62–3.45 ‰ (avg. 2.35 ‰) for Py-1, 0.18–3.12 ‰ (avg. 1.85 ‰) for Py-2a, and 0.62–4.18 ‰ (avg. 2.51 ‰) for Py-2b. These characteristics may have played a vital role in the initial enrichment of Cu, Mo, Au, and ultimately formed the complex polymetallic system at Beiya.

Features of ore-forming magma and fluid revealed by apatite and zircon geochemistry: A case study from the Huanggang skarn Fe-Sn deposit, NE China

The large-scale Huanggang Skarn Fe-Sn deposit is located in the southern part of the Great Xing’an Range (SGXR), NE China. The causative granitic rocks in the Huanggang ore district are characterized by consistently high SiO2 contents, low EuN/EuN* (0.02–0.24) and Sr/Y (0.2–1.9). The pre-ore granite porphyry and syn-ore syenogranite have been dated through zircon and monazite U-Pb dating at 144.6 ± 1.4 Ma and 138.6 ± 1.3 to 135.9 ± 0.8 Ma, respectively. The U-Pb dating of garnet from ore-associated skarn reveals that the mineralization was happened at 136.5 ± 1.3 Ma, which is consistent with the emplacement age of the ore-related syenogranite.Zircon geochemistry shows that the pre-ore granite porphyry has relatively low oxygen fugacity (average zircon Ce4+/Ce3+ = 14.74), whereas the syn-ore syenogranite is more oxidized (average zircon Ce4+/Ce3+ = 178.9). We suggest that the elevation of oxygen fugacity was most likely caused by degassing. The textural features indicate that apatite crystals from the pre-ore granite porphyry are magmatic in origin. In contrast, textural and chemical characteristics of apatite grains from syn-ore syenogranite reveal that they have been modified by hydrothermal fluids in different degrees. The apatite in both pre- and syn-ore granites display relatively high F and low Cl contents, and very low SO3 concentrations (i.e., <0.032 wt%), indicate extremely low content of S in the causative magma. Apatite from syn-ore syenogranite display more strong and variable enrichment of LREE relative to HREE compared to those from pre-ore granite porphyry. The extensive present of new REE mineral inclusions (monazite and xenotime) in the altered apatite suggests that the concentrations of Ca and Na must be low in the ore-forming fluid. Apatite from syn-ore syenogranite have higher concentrations of Mo, W, Zn, Sn, and Be than those from pre-ore granite porphyry.Combined with zircon and apatite geochemistry, and whole rock components of the ore-related granites in the Huanggang deposit, we propose that the ore-forming magma has undergone long-term evolution under relatively reduced conditions with extensive fractional crystallization of plagioclase. The reduced and S-poor evolved magma could have promoted the enrichment of Sn and prevented Fe from precipitating as sulfide. This study also reveals that the compositional characteristics of ore-forming fluid, such as the enrichment of ore-forming materials, could be revealed by altered apatite geochemistry.

Pulsatile extractions of Lower Cretaceous silicic volcanic plumbing system beneath the Baiyunzhang and Lianhuashan basins, eastern Guangdong: silicic magma evolution and related mineralization

Highly differentiated magmas are closely related to the formation of tin deposits. The Lianhuashan Basin and Baiyunzhang Basin, surrounded by multiple coeval tin deposits, developed various types of volcanic and subvolcanic rocks. The diagenetic connections between different types of rocks within the two basins provide new insight into the evolution of the silicic magma systems and the impact of highly differentiated magmas on tin mineralization. Both basins have consistent zircon U–Pb ages (143–138 Ma) and similar whole-rock Nd isotopes ( ε Nd ( t ) = −5.7 to −3.4) and zircon Hf–O isotope ranges ( ε Hf ( t ) = −9.0 to −2.5; δ 18 O = 5.1–7.9), suggesting that both basins originate from the same deep-level magma reservoir, followed by different degrees of crystal differentiation and several episodes of crystal–melt separation in their respective shallow-level magma reservoirs. The multiple pulses of magma extraction eventually produced different volcanic rocks (granite porphyry and rhyolite porphyry), whereas the remaining crystal mush consolidated in situ to form quartz monzonite porphyry. Further studies show that the tectonic regime changed from a compressive to an extensional environment at c . 140 Ma. Consequently, mantle-derived magmas with low oxygen fugacity injected shallow magma reservoirs that were able to evolve to a high degree of differentiation through multiple recharge, thus favouring the formation of the Sn deposit.

Discovery and Exploration of the Luming Porphyry Mo Deposit, Northeastern China: Implications for Regional Prospecting

Over the past two decades, significant deposit discoveries were made in Northeastern China, including the super-large Chalukou, Daheishan, and Luming porphyry Mo deposits. The discovery of the Luming deposit was accomplished through verification of stream sediment anomalies, with mineralization closely associated with early Jurassic monzogranite and granite porphyry. Previous studies primarily focused on the mineralization mechanisms of these deposits without adequately addressing the exploration methods and prospecting criteria. This study involved a comprehensive re-evaluation of geological observations, analysis of rock primary halo, gravity and magnetic surveys, and induced polarization surveys conducted during exploration campaigns at the Luming porphyry Mo deposit. The results suggest that hydrothermal breccias play a critical role in controlling the mineralization by forming a central low-grade core within the deposit while the Mo mineralization and hydrothermal alteration exhibit a donut-shaped distribution around it. The primary halo shows a distinct metal zonation moving from a central W-Bi-Mo-(Sb) to a peripheral Cu-Co-Ni and a distal Pb-Zn-Ag-In. The mineralization zone exhibits a low Bouguer gravity anomaly, negative magnetic anomaly, medium to low resistivity, and moderate to high chargeability, indicating the effectiveness of geophysical methods in defining the extent of the ore body. The Luming porphyry Mo deposit and distal skarn-epithermal Pb-Zn mineralization are parts of a porphyry-related magmatic-hydrothermal system. The results of this study offer valuable insights into the genesis of porphyry Mo deposits and their implications for prospecting in the forested region of Northeastern China.

Petrogenesis and Tectonic Implications of the Granite Porphyry in the Sinongduo Ag-Pb-Zn Deposit, Central Tibet: Constraints from Geochronology, Geochemistry, and Sr-Nd Isotopes

Petrogenesis and Tectonic Implications of the Granite Porphyry in the Sinongduo Ag-Pb-Zn Deposit, Central Tibet: Constraints from Geochronology, Geochemistry, and Sr-Nd Isotopes

Geochronology, geochemistry, and isotope signatures of porphyries from the dabate Mo—Cu deposit, Western Tianshan, China: Implications for petrogenesis and geodynamic setting

The Dabate deposit in the West Tianshan Orogenic Belt is a large porphyry Mo-Cu deposit with obvious zoning feature. The Dabate pluton is closely related to mineralization associated with the rhyolite and granite porphyries. Copper (Cu) mineralization occurs on the margin of the rhyolite porphyry, and molybdenum (Mo) mineralization occurs in the interior of the rhyolite porphyry. Petrology, zircon U-Pb isotopic data, whole-rock geochemistry, and Sr-Nb-Hf-Pb isotopic data of the rhyolite and granite porphyries in the Dabate Mo-Cu mining zone and to discuss the properties, sources, evolution, and tectonic environment of the magma. Zircon U-Pb age dating shows that the rhyolite porphyry and granite porphyry were formed in 300.1 ± 1.3 Ma and 290.4 ± 5.2 Ma, respectively, and they are geochemically similar. Both are characterized by negative Eu anomalies (δEu = 0.09–0.15 and 0.10–0.11, respectively) and are slightly rich in light rare earth elements (LREE) but depleted in high-field-strength elements (HFSE), which indicates that they are both A2 type granites that underwent high differentiation. The Sr isotope (ISr) values for the rhyolite and granite porphyries range from 0.70564 to 0.70658 and 0.70833–0.70954, respectively. The Nd isotopic composition [εNd(t)] values for both are negative but close to zero (−0.25 to −0.46 and −0.65 to −1.10, respectively), and the two-stage depleted mantle Nd model ages (TDM2(Nd)) are 1.07–1.10 Ga and 1.11–1.14 Ga, respectively. Zircon εHf(t) values are 7.29–11.97 and 6.26–11.08 for rhyolite porphyry and granite porphyry, respectively, and the two-stage Hf model ages (TDM2(Hf)) are 550–848 Ma and 605–916 Ma, respectively. The initial Pb isotope ratios for the rhyolite and granite porphyry are close at (206Pb/204Pb)i = 18.26–18.65, (207Pb/204Pb)i = 15.54–15.64, and (208Pb/204Pb)i = 38.19–38.57. These results indicate that the two porphyries have a mixed source, likely originating from the partial melting of mantle blended with some recently formed lower crust material. The geochronology, geochemistry, and Sr-Nd-Hf-Pb isotope data of existing intrusions in the West Tianshan imply that the Late Carboniferous to Early Permian Dabate area was underplated in a post-collisional extensional setting, and A2-type granite intrusions with related Mo-Cu mineralization were formed.

Geology and genesis of the Aqishan Pb-Zn deposit, NW China: Insights from mineralogy, geochemistry, and in situ U-Pb geochronology

The unique ore-forming processes and the key factors responsible for formation of skarn deposits are still obscure, and challenges exist in the determination of timing of Pb-Zn skarns owing to lacking suitable mineral chronometers. Here we present detailed paragenesis, bulk geochemistry, in situ U-Pb dating of zircon and garnet, and garnet oxygen isotopes together with in situ zircon Hf-O isotopes from the newly discovered Aqishan Pb-Zn deposit in the southern Central Asian Orogenic Belt (CAOB), northwest China. This comprehensive data set revealed a Late Carboniferous subduction-related distal Pb-Zn skarn system associated with the granitic magmatism. Pre-ore stage garnets are generally subhedral to euhedral with oscillatory zoning and show slightly fractionated rare earth element patterns with positive Eu anomalies that point to an infiltration metasomatism origin under high water/rock ratios. The syn-ore stage sphalerite is typically enriched in Mn and Cd and has moderate Zn/Cd ratios (337–482), with a formation temperature of 265 °C to 383 °C, which indicate magmatic-hydrothermal signatures. The isocons defined by P2O5 decipher that the principal factors for skarn formation were elevated activities of Fe, Ca, and Si species, where remobilization of Pb metals, meanwhile, contributed to ore-forming budgets to mineralizing fluids. SIMS U-Pb dating of zircons from granite porphyry that occurs distal to the skarns and Pb-Zn orebodies shows that these intrusions emplaced at ca. 311.3–310.6 Ma, recording the subduction of the Paleo-Tianshan oceanic plate. Hydrothermal garnets in close textural association with Pb-Zn sulfides yield indistinguishable in situ LA-ICP-MS U-Pb ages of 310.5 ± 4.1 Ma. Whole-rock geochemistry and in situ zircon Hf-O isotopes (δ18O = 4.6‰–6.0‰) indicate that the granite porphyry was derived from partial melting of juvenile crust and influenced by subducted oceanic crust. Oxygen isotope compositions of garnets (δ18O = 8.0‰–9.0‰) demonstrate that the equilibrated ore fluids were inherited from fluid-rock interactions between a primary magmatic water and host tuff rocks. Our study highlights the application of garnets as a potential robust U-Pb geochronometer and isotopic tracer of ore fluids in skarn mineralizing systems in subduction-related arc environments.

Investigation of rock genesis and geodynamic significance based on Sr–Yb granite classification and geochemical characteristics: A case study from Guangxi, China

The intrusive bodies in the study area are categorized into two intrusive units, γπK2 and ηoπK2, based on rock structure characteristics and intrusive contact relationships. The primary lithologies are granite porphyry and quartz monzonite porphyry. Through LA-ICP-MS zircon U–Pb dating, the weighted mean ages of zircon ^206Pb/^238U for these two units were determined to be 84.09 ± 0.86 Ma and 86.10 ± 0.76 Ma, respectively. According to geochemical characteristics and Sr–Yb granite classification, the quartz monzonite porphyry is classified as Zhejiang-Fujian type granite, and the granite porphyry as Nanling type granite. The study explores the geodynamic significance of granites in the area based on Sr–Yb granite classification, identifying the lower crust metamorphic facies as amphibolite facies. The source rocks are primarily basic granulites and felsic granulites, reflecting a thermally active lower crust with poorly developed fluids. Additionally, Sr–Yb granite classification aids in determining the crustal thickness of the lower crust, which is crucial for understanding continental geological evolution. This paper discusses the optimal locations and conditions for mineralizing fluid precipitation, noting that tungsten-tin mineralization is associated with Nanling type granites and that the mineralization process generally occurs later than the diagenetic process under conditions of low pressure and low oxygen fugacity. Tungsten-tin prospecting should focus on areas where the surrounding rock temperature ranges from 300 to 500 °C, with particular attention to the contact zones of sedimentary rocks or near structural fault zones.

The Weixi High‐silica Granitoids in the Central Sanjiang Orogenic Belt, Southwest China: Implications for Growth of the Continental Crust

AbstractHigh‐silica granitoids record the formation and evolution of the continental crust. A new intrusive complex has been recognized among silicic volcanic rocks of the Weixi arc, Southwest China. The intrusions consist of granites, granitic porphyries, and granodiorites. Zircon U‐Pb age data indicate that the Weixi granitoids formed at 248–240 Ma and were coeval with silicic volcanic rocks of the Weixi arc. The Weixi granitoids are enriched in Rb, Th, and U, depleted in Ba, Sr, Nb, Ta, and Ti, and have high light/heavy rare earth element ratios and slightly negative Eu anomalies. The Weixi granitoids have negative εNd(t) values (–9.8 to –7.8) and negative zircon εHf(t) values (–12.02 to –5.11). The geochemical and isotopic features suggest the Weixi granitoids were derived by partial melting of ancient crustal material. The Weixi granitoids and silicic volcanic rocks were derived from the same magma by crystal accumulation and melt extraction, respectively, and they record the formation of a continental arc in the central Sanjiang orogenic belt.

Age and petrogenesis of ore-bearing porphyry from the Houyu Mo-polymetallic deposit, central North China Craton

Porphyry-related molybdenum deposits formed within the plate's interior are unique, yet the understanding of the magmatic hydrothermal Mo system remains limited. Houyu is a typical porphyry-related Mo-polymetallic deposit situated in the inner region of the North China Craton (NCC). The ore bodies are found in Archean biotite plagioclase gneiss and diorite, followed by Early Cretaceous quartz porphyry, granite porphyry, and brecciated porphyry. Zircon U-Pb dating reveals that the biotite plagioclase gneiss, quartz porphyry, and granite porphyry were formed at 2499.2 ± 7.8 Ma, 135.19 ± 0.67 Ma, and 137.65 ± 0.84 Ma, respectively. Molybdenite Re-Os dating indicates a mean age of 134.94 ± 0.76 Ma and an isochron age of 134.7 ± 1.5 Ma, linking the Mo-polymetallic mineralization closely to the Early Cretaceous porphyry. The Houyu Cretaceous porphyry exhibits enrichment in light rare earth elements (LREEs), depletion in heavy rare earth elements (HREEs), and distinct positive Eu anomalies. Additionally, they are enriched in fluid-mobile large-ion-lithophile elements (LILEs) and significantly depleted in high-field-strength elements (HFSEs). These geochemical attributes suggest that the Cretaceous porphyry belongs to I-type adakitic granites. All samples exhibit consistently negative εNd(t) values ranging from −15.76 to −14.87 and εHf(t) values between −20.69 and −14.78, along with restricted 206Pb/204Pb (16.557–16.663), 207Pb/204Pb (15.262–15.300), and 208Pb/204Pb (36.601–36.747) ratios, indicating that they were derived from an ancient thickened lower continental crust (LCC). The Cretaceous magmatism and mineralization of the Houyu Mo-polymetallic deposit could be closely linked to the lithospheric thinning and destruction of the NCC triggered by the Paleo-Pacific or Izanagi Plate.