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The subduction-related Sunda-Banda arc hosts several giant and major Cu–Au–Mo porphyry and epithermal Au systems, making it one of the most important magmatic-related metallogenic belts in Indonesia. They are accompanied by a number of smaller systems, one of which is the recently discovered Randu-Kuning porphyry Cu-Au deposit on Java Island. The present study investigates the geochemical characteristics of this deposit through whole-rock and mineral geochemistry and mineral geothermobarometry, focusing on three sequential dioritic intrusions that make up the host igneous complex, two barren and the third mineralized. Moreover, a comparative analysis is performed between other porphyry deposits in the Sunda-Banda arc and with Grasberg in Papua. This study shows that the older porphyry deposits have mostly similar geochemical characteristics to the younger deposits, suggesting the same magma source, which is mantle-derived oxidized I-type magma. Amphibole geothermobarometry shows that the formation of syn-ore intrusion in the older porphyry was higher in temperature and pressure than those at the younger porphyry. The halogen and oxygen fugacities inferred from biotite and amphibole chemistry indicate an oxidized, water- and halogen-rich melt. Our study shows that combining amphibole and biotite chemistry and whole-rock geochemical data is useful to fingerprint the magmatic-hydrothermal processes, especially where multiple magmatic phases occur. This research also provides valuable insights into the magmatic-hydrothermal physiochemical conditions during the formation of the mineralized system. [ABSTRACT FROM AUTHOR]

Late Palaeozoic evolution of the Chinese Altai-East Junggar orogenic collage is vital for a better understanding of the accretionary evolution in the southern Altaids. This paper reports new geochronological, geochemical, and isotopic data for the magmatic rocks collected from the northern part of the Dulate arc. The ~304.6 Ma tonalite samples present typical adakitic features of high Sr (396–714 ppm), low Y (1.42–2.60 ppm), Yb (0.11–0.24 ppm), and high Sr/Y (177.25–440.23) ratios. Combining high Mg# (55.35–57.21) and depleted isotopic composition (εHf(t): +9.89 to +13.37 and εNd(t): +5.36 to +6.06), we suggest that they were derived from the partial melting of a subducted oceanic slab. The ~299.4 Ma monzogranite samples have high A/CNK values (1.08 to 1.25), CIPW normative corundum contents (1.28–3.25 wt.%), and positive εHf(t) (+5.14 to +8.63) and εNd(t) (+1.08) values, which are similar to S-type granite that may be generated by the melting of greywackes. The monzogranite (~286.9 Ma) and rhyolitic porphyry (~283.9 Ma) are high-K calc-alkaline and similar to the highly fractionated I-type granites with depleted isotopic features (εHf(t): +11.68 to +14.99 and +0.75 to +7.18, εNd(t): +5.91 and +6.18). The monzogranite and rhyolitic porphyry could have been derived from a depleted mantle source, but the rhyolitic porphyry probably suffered partial assimilation of the overlying crust materials. Combining regional rock associations of mafic-ultramafic complexes, adakitic rocks, high-Mg diorites, and A-type granites with close spatial-temporal relationship, we conclude that a mid-oceanic ridge of the Ob-Zaisan Ocean subducted southward beneath the Dulate arc during the latest Carboniferous to Permian. With the opening of the slab window, the upwelling asthenosphere provided high heat flux and triggered various magmatism in the upper plate. We propose that ridge subduction is one of the most effective mechanisms of continental growth in the southern Altaids. [ABSTRACT FROM AUTHOR]

The Late Triassic igneous rocks associated with post-collision are widely distributed in the East Kunlun Orogenic Belt (EKOB), but their specific dynamic mechanism and evolutional process are still controversial. To address these key issues, we investigated the geochronology and geochemistry of intermediate–felsic igneous rocks from the EKOB, including trachyandesite, rhyolite, porphyritic monzogranite, syenogranite, granite porphyry and crystalline tuff. Zircon U–Pb isotopes of these rocks indicate that they were formed between 231.1 and 215.8 Ma (i.e. Late Triassic). These igneous rocks have moderate to high SiO2 (60.29–79.56 wt%) and low mantle compatible element contents (e.g. Co: 0.37–12.62 ppm; Ni: 1.55–15.59 ppm), suggesting that continental crustal-derived material played an important role in their formation. Porphyritic monzogranite (231.1 Ma), syenogranite (228.1 Ma), trachyandesite (227.4 Ma) and rhyolite (215.8 Ma) have Nb/U (1.41–4.71) and Ce/Pb (1.48–6.19) ratios like that of the crust, with εHf(t) values (–1.31 to 2.26) and old two-stage model (TDM2) ages of 1340–1119 Ma, suggesting that they originated from the partial melting of a Mesoproterozoic crust with minor mantle material involved in their source. Crystalline tuff (224.6 Ma) and granite porphyry (222.3 Ma) have Nb/U (1.93–3.81) and Ce/Pb (0.30–3.18) ratios, negative εHf(t) values (–7.04 to −5.12) and old TDM2 ages (1703–1581 Ma) closer to those of crust, suggesting that they were derived from the partial melting of a Paleo–Mesoproterozoic continental crust without addition of mantle material. Based on our new data and published data, the Late Triassic igneous rocks from the EKOB can be divided into three stages, 236–227, 226–218 and 216–208 Ma, corresponding to slab break-off, lithospheric mantle delamination and thickened lower crust delamination, respectively. The intermediate–felsic igneous rocks from the East Kunlun Orogenic Belt are dated from 231.1 to 215.8 Ma (i.e. Late Triassic). These igneous rocks were derived from the partial melting of ancient continental crust. The Late Triassic igneous rocks from the East Kunlun Orogenic Belt can be divided into three stages, including slab break-off, lithospheric mantle delamination and thickened lower crust delamination. [ABSTRACT FROM AUTHOR]

The Clarke River Fault in northeast Queensland records an early Paleozoic history of subduction, accretion and continental suturing. Samples of mafic-ultramafic rocks collected proximal to the Clarke River Fault record oceanic geochemical affinities and comprise alteration assemblages consistent with an ophiolitic origin. The ca 456Ma Falls Creek Tonalite records a continental-arc geochemical signature and was formed in response to long-lived subduction beneath the Thomson Orogen. Ordovician subduction beneath the Thomson Orogen is broadly coeval with arc magmatism documented in the Lachlan Orogen, which has been associated with the formation of several large porphyry ore deposits. The Falls Creek Tonalite yields adakite-like geochemical signatures that reflect a fertile melt source conducive to the formation of porphyry ore deposits. The outcropping plutons record ductile deformation consistent with mid-crustal depths, and they were emplaced during late syntectonic activity. This implies that the Falls Creek Tonalite was emplaced at too great a depth to have formed porphyry ore deposits. The northern Charters Towers Province shares many geological similarities to the Greenvale Province, where the erosional level may be shallower, and the potential for porphyry deposit formation and preservation may be greater. [ABSTRACT FROM AUTHOR]

A diversity of Devonian-Carboniferous volcanic arcs and granitoid intrusions are exposed in the Gurvansaykhan arc terrane of southern Mongolia. Several giant porphyry Cu-Au-Mo deposits are associated with intrusions within these arcs. The Bronze Fox deposit located in the central part of the Gurvansaykhan arc terrane is an example of a potentially economic deposit with affinity of adakite-like granitoid porphyry (i.e. 428 Mt grading 0.26% to 0.30% Cu for up to 2,437 Mlb of copper and 0.84 Moz gold). The genesis and magmatic evolution of the causative rocks of the Bronze Fox porphyry Cu-Au hosting rocks are poorly understood, and different models are still under debate. In the current study, we present new field observations and petrographic, geochemical, and geochronological data to describe the magmatic evolution and geodynamic settings. In addition, the mineral chemical data are reported from some selected rock-forming minerals to identify crystallization conditions of the studied rock suites by employing geothermobarometric methods. Zircon chronological data reveal the emplaced age at 331 ± 3.4 Ma for the volcanic lava, followed by mineralized granodiorite and monzodiorite with intruded ages of 326.5 ± 3.4 Ma and 326.5 ± 2.7 Ma, respectively. The studied intrusive and extrusive rocks are high-K-alkaline and metaluminous, characterized by high Mg#. They are enriched in large ion lithophile elements (Sr and Ba) and light rare earth elements (LREEs) and depleted in high field strength elements (Nb, Ta, and Ti) and heavy rare earth elements (HREEs). The highly mineralized granodiorite intrusion yields zircon crystallization temperatures ranging from 631.8 to 779.4°C, and the monzodiorite intrusion, which contains relatively low-grade mineralization, has a wider range (599.0 to 803.4°C). The formation pressures of the former range from 0.5 to 0.2 kbar, which is equivalent to a depth of 1.38 km based on amphibole geochemical calculations. The results of mineral chemistry indicate that the unmineralized diorite unit was formed under medium pressure (~50 MPa) and high temperature (~750°C) at depths of 6.8 to 7.5 km. Similarities in geochemistry and petrographic features suggest that the igneous rocks probably originated from a similar magma source (i.e. from the melting of ancient oceanic crust and sediments) but experienced different degrees of partial melting or mixing with lower juvenile crust melts. The estimated fO2 values obtained by amphibole chemistry in the granodiorite and quartz diorite of the Bronze Fox copper-gold mineralization range from −13.0 to −11.8 and −13.2 to −10.8, respectively, confirming that these igneous rocks probably crystallized under relatively oxidized conditions above the nickel-nickel oxide (NNO) buffer. Such results yield an overall range between NNO +2.6 and NNO +1.4, which are characterized by high oxygen fugacities and high Ce4+/Ce3+ ratios that reflect oxidizing magma, thus indicating quite promising potential for porphyry Cu-Au mineralization in the region. Based on the findings of this work, we suggest a new tectonic model of arc magmatism that is a response to the subduction of the Paleo-Asian Ocean in the early Carboniferous period. [ABSTRACT FROM AUTHOR]

Copper–gold porphyry deposits are the world's main source of copper and a significant source of gold. They consist of vein networks and their surrounding alteration zones. Commonly the deposits are centred on narrow intrusions (stocks), but calling these deposits 'porphyries' is unjustified because the name carries little descriptive or genetic value. Extensional veins were formed by hydraulic fracturing of the stocks, at depths where open spaces could not be maintained and where fluid pressure approaches lithostatic pressure. The post-crystallisation timing of the veins is important because it indicates that the host stocks could not have been the direct sources of either metals or ore-forming fluids. In the traditional magmatic model, precursor batholiths, lying at depth, are inferred to be the sources of the Cu and Au in the overlying host stocks. In this model, the batholiths are assumed to have crystallised and produced the mineralising aqueous fluids, Cu and Au. However, in many porphyry deposits, the concept of metal and fluid supply from deeper batholiths is problematic. Neither Cu nor Au is strongly enriched during the crystallisation of silicate magmas, and although hypersaline fluids are a characteristic of Cu–Au porphyry deposits globally, the source of the Cl remains unconstrained. There is little evidence that silicate magmas can release such Cl-rich fluids, and it remains unexplained how elevated levels of Cl may be achieved in a silicate magma. Therefore, the starting assumption that these deposits formed predominantly from magmatic sources and processes is questioned. This study has selectively focused on the roles of rheology, rock mechanics, vein control, metal-enrichment processes and the sources of Cl. Non-magmatic processes may be enough to facilitate strong partitioning of Cu and Au into high-temperature, oxidising, high-salinity, hydrothermal fluids to form Cu–Au porphyry deposits. Mineralised quartz veins were introduced in fluids during hydraulic fracturing of their host intrusions when these stocks were brittle and had cooled significantly below their solidus temperatures. The porphyry intrusions hosting Cu–Au (copper–gold) mineralisation were not the direct sources of either the fluids or the metals. The sources of Cu and Au included large volumes of surrounding and underlying rocks up to kilometres from the sites of deposition. Cu and Au do not become strongly concentrated during crystal fractionation in evolving silicate magmas. Unaltered igneous rocks have relatively low Cl contents, and experiments suggest low Cl solubilities in granitic to granodioritic magmas. It is highly unlikely that all the Cl required for metal complexing and transport was available from within silicate magmas. [ABSTRACT FROM AUTHOR]

Dilution effects should be considered in the estimated model of deposit due to its significant impact on feasibility studies, mine planning and scheduling, milling, and stockpiling. This work compares the capacity of two approaches for modelling dilution of intrusive barren dykes into the ore body in a copper deposit. Two approaches were used to generate an undiluted model of copper grade in a copper deposit, which is cross cut by intrusive dykes. The results demonstrated that the second approach is more advantageous in comparison with the first approach, especially when there is hard contact between the ore and barren dykes. [ABSTRACT FROM AUTHOR]

Anorogenic magmatism in the northern Arabian-Nubian Shield occurred during a long-lasting crustal extension event (<580 Ma), which succeeded the formation of the Pan-African orogenic belt in NE Africa and Arabia. Late Neoproterozoic anorogenic felsic volcanic-subvolcanic rocks, along with post-collisional granitoid suites, are exposed in the Gabal Abu Durba mountain range along the eastern flank of the Gulf of Suez in Sinai. These rocks include granite and rhyolite porphyries, metaluminous to weakly peralkaline with distinct potassic alkaline and ferroan affinities. Major and trace element characteristics such as K2O/MgO >16, total alkalis >8.5 wt.%, (K2O + Na2O)/CaO >10, agpaitic index (NK/A) >0.85 and Zr (>250 ppm), Nb (>20 ppm), Y (>80 ppm), Zn (>100 ppm) and Ce (>100 ppm), and 10,000 × Ga/Al >2.6 and [Zr + Nb + Y + Ce] >350 ppm are suggestive of an A-type granite genesis. Zircon U-Pb dating of two representative samples returned crystallization ages of 569 ± 2.6 Ma and 561.7 ± 3.2 Ma for granite and rhyolite porphyries, respectively. The melting temperatures estimated at 997–1020°C are consistent with high-temperature liquidus conditions. Fractional crystallization, coupled with less significant crustal assimilation, was likely the main mechanism of formation of these rocks from a common primitive asthenospheric mantle-derived trachytic magma in an anorogenic intra-plate setting. The A-type alkali granite and rhyolite porphyries of Gabal Abu Durba are manifestations of mantle upwelling and lower crust underplating in the late Ediacaran anorogenic stage. These felsic subvolcanic intrusions (≈ 569–562 Ma) along with their volcanic counterparts constitute a new unmatched rock unit that most probably represent the last chapter of the anorogenic magmatism in the Neoproterozoic Arabian-Nubian Shield crust before the beginning of Phanerozoic era. [ABSTRACT FROM AUTHOR]

The North Tianshan Ocean represents a critical southwestern segment of the Paleo-Asian Ocean and is crucial for understanding accretionary and collisional processes of the southwestern Central Asian Orogenic Belt. The Dananhu arc belt, an important porphyry Cu deposit metallogenic belt in the eastern North Tianshan, records Paleozoic episodic magmatism. However, the tectonic affinity and evolution processes of the Dananhu arc belt are still open to debate. Here, geochronology, major and trace elements, and Sr-Nd-Hf isotope compositions for magmatic rocks are conducted to reveal the ages, petrogenesis, and tectonic settings of these magmatic rocks in the Dannanhu arc belt. The Carboniferous dacite (328 Ma) and gneissic granite (310 Ma) show high-K calc-alkaline, enriched in large ion lithophile elements (LILEs; e.g. Rb, Th, and U), depleted in high field strength elements (HFSEs; e.g. Nb, Ta, and Ti), depleted isotopic compositions (εNd(t) = 1.3-3.4; εHt(t) = 0.5-12.5) and juvenile Nd-Hf model ages. Combining these Carboniferous magmatic rocks with the features of high Sr-Ba granitoid and Sr-Nd isotopic decoupling, we suggest that these Carboniferous rocks were probably formed through fractional crystallization of partial melting of mantle wedge that had been metasomatized by melts from subducted sediments in a forearc setting. The early Permian granites (289-276 Ma) show high K2O+Na2O (6.9-8.9 wt.%), low MgO (0.06-0.15 wt.%) contents, high positive zircon εHt(t) (10.5 to 12.1) and whole-rock εNd(t) (4.4-5.5) values, suggesting that the early Permian granites were derived from juvenile lower crust in a post-collisional setting. Our geochronological and geochemical data, together with published data, reveal that high flux arc magmatism with age peaks at ca. 431 and 332 Ma is consistent with porphyry copper mineralization in the Dananhu arc belt, implying a close genetic relationship. The final closure of the North Tianshan Ocean was constrained to the late Carboniferous and early Permian. [ABSTRACT FROM AUTHOR]

One of the specific features of porphyry copper (Cu) mineralization is the distinct occurrence of hydrothermal alteration zones, which can be mapped by processing various satellite images. Among free multispectral images, Landsat 8 OLI and ASTER data are known to be efficient in mapping different geological features, such as alteration zones and tectonic lineaments. This study aims to show the potential of these data types in mapping porphyry Cu mineralization by proposing a framework for employing and integrating different image processing methods. These methods include principal component analysis (PCA), spectral angle mapper (SAM), and matched filtering (MF) employed on these satellite images to map target al.teration zones. Moreover, PCA and directional filtering are applied to the ASTER dataset to enhance and map structural features. The results are evaluated and then combined to provide a potential map of Cu mineralization in the Chahargonbad area, located within the Urumieh-Dokhtar magmatic belt (UDMB) in Kerman province, Iran. The prediction-area plot and normalized density, which are data-driven methods, are used to assign the relative weight of each layer and evaluate them. Finally, using the calculated weights, data-driven multi-index overlay (DMIO) and fuzzy ordered weighted averaging (FOWA) methods are applied to combine the evidential layers. The potential mineralization maps created by the DMIO and FOWA provide a prediction rate of 80% and 82%, respectively. Furthermore, the accuracy of the integrated maps is investigated using the area under the curve (AUC) of the receiver operating characteristic (ROC) curves. The AUC scores obtained from the ROC curves of DMIO and FOWA methods are 0.85 and 0.88, respectively, representing powerful positive spatial relationships with mineralization areas. Based on the results, the proposed framework can be applied to provide a potential map of porphyry Cu mineralization, particularly in arid regions, with reasonable accuracy. [ABSTRACT FROM AUTHOR]

Epithermal deposits occur in many metallogenic belts globally and are economically important sources of precious and base metals. However, post-mineral cover (both transported and younger deposits) also occurs in many prospective districts and hinders exploration efforts. Hydrogeochemistry is a potentially useful exploration tool in these environments, with water–rock interaction shown from other studies to produce large hydrogeochemical footprints. Groundwaters from in and around the Vaquillas (Au-Ag) epithermal deposit in the pre-cordillera of northern Chile are typically Ca-SO42- type with meteoric upflow groundwaters interacting with the ore body and producing a significant downflow (down hydraulic head) mobility (up to 3 km) of (oxy)anions of arsenic and molybdenum, which contrasts with proximal trace cation anomalies. Multiple sulphur endmembers contribute to the dissolved sulphate concentrations, including evaporites, primary hypogene sulphide minerals, and a single δ34S(SO4) value of 30.1 ‰ which is potentially associated with disproportionated sulphur in sulphate. This study reports anomalism from one of the most dilute endmember groundwater compositions from Chile reported to date. The sub-alkaline and weakly oxygenated groundwaters are common in many aquifers globally, making the results applicable to many other metallogenic belts. It is also the first hydrogeochemical case study of an intermediate-sulfidation epithermal deposit. Despite the highly dilute groundwaters recharging aquifers at Vaquillas, we conclude hydrogeochemistry to be a highly effective exploration tool for epithermal and porphyry deposits in areas of significant post-mineral cover. [ABSTRACT FROM AUTHOR]

Detection of hydrothermal alteration zones (HAZs) associated with porphyry copper systems using remote sensing imagery is a crucial stage for discovering high potential zone of ore mineralization. Statistical model-based clustering methods have great potential for automatic and accurate detection of hydrothermal alteration minerals using hyperspectral remote sensing imagery. In this research, the Dirichlet Process based on Stick-Breaking (DPSB) model-based clustering algorithm was implemented to hyperion remote sensing imagery to discriminate HAZs associated with the Kuh-Panj porphyry copper deposit, south, Iran. The DPSB clustering algorithm was implemented and subsequently compared with the k-means algorithm, CLARA clustering, hierarchical clustering, Gaussian finite mixture model (GFMM), Gaussian model for high-dimensional (GMHD) and spectral clustering as well as spectral angle mapping (SAM). Results derived from the DPSB model-based clustering algorithm show 88.6% accuracy in distinguishing propylitic, argillic, advanced argillic, propylitic-argillic and phyllic alteration zones. The DPSB algorithm can be broadly implemented to hyperspectral remote sensing imagery for detecting alteration zones associated with porphyry systems. [ABSTRACT FROM AUTHOR]

Early Paleozoic subduction beneath peri-Gondwana microcontinents formed a major Proto-Tethys magmatic arc system. Appinite suite rocks constitute important components within that magmatic arc. Herein, we report hornblende 40Ar/39Ar and zircon U–Pb geochronology data, zircon Hf isotope, mineral chemistry, whole-rock geochemistry, and Sr–Nd–Pb isotope data for the rocks of hornblende gabbro-diorite-quartz diorite-quartz monzodiorite from the Renda appinite suite and adjacent granite porphyry in the southeastern Qilian Orogen. Hornblende 40Ar/39Ar and zircon U–Pb isotopic data constrain ages of the intrusions of the Renda appinite suite to 439–435 Ma. Rocks in this suite represent the calc-alkalic to alkali-calcic series, and they are enriched in large-ion lithophile elements and depleted in high-field-strength elements. The hornblende gabbros exhibit moderate initial 87Sr/86Sr ratios (0.7046–0.7055) and higher whole-rock εNd(t) (–1.3 to +1.7) and zircon εHf(t) (+7.2 to +11.2) values relative to the other rocks of the suite (0.7047–0.7064, – 7.7 to – 1.1, and – 6.6 to +6.8, respectively) as well as Pb isotopic features similar to EM2 lithospheric mantle. These geochemical characteristics suggest that the Renda appinite suite originates from partial melting of an enriched lithospheric mantle, with subsequent fractional crystallization and hybridization with crustal components. The granite porphyry formed by partial melting of the crust coeval with the emplacement of juvenile magma. This study suggests emplacement occurred during a short-lived collision with slab failure (breakoff) after latest stage (cessation) of Proto-Tethys oceanic subduction along the northern side of the southeastern Qilian Orogen. The heat supplied by the asthenospheric upwelling through a gap in the subducted slab induced melting in lithospheric mantle and deep crust producing Renda appinite suite rocks and granite porphyry. [ABSTRACT FROM AUTHOR]

Only a handful of stratified sites are known in loess, spring, and river contexts in the northern piedmonts of the Tian Shan, and the majority are dated to the Upper Palaeolithic. These sites have been studied from a geoarchaeological perspective; however, lithic procurement activities remain unknown. To address this deficiency, we present the results of the extensive field surveys aimed at locating prehistoric raw material sources in the Inner Asian Mountain Corridor of Kazakhstan. We also provide a detailed petrographic description of the lithologies exploited during the Palaeolithic of Kazakhstan. Based on the field survey results, combined with petrographic data, we conclude that the direct procurement strategy was the most common at the stratified sites. However, evidence of both direct and embedded procurement is found in the northern piedmonts of the Ili Alatau range at the site of Maibulaq. Additionally, we highlight the variation of chert lithologies within the larger Qaratau region, laying a foundation for future provenance studies. [ABSTRACT FROM AUTHOR]

The Late Carboniferous to Early Permian tectonic evolution of the South West Junggar (SWJ), northwest China, a crucial constituent in the southwestern domain of the Central Asian Orogenic Belt (CAOB), has long been the subject of debate. Here, detailed petrographic studies, new nine LA-ICP-MS zircon U-Pb ages and forty-nine whole-rock geochemical results from six granitic plutons in the SWJ were combined with previously available data to elucidate their petrogenesis and re-decipher Late Palaeozoic tectonic evolution and accretionary process of the southwestern CAOB. The studied granites can be geochemically classified as I- and A-type granites, and the former is further subdivided into I-type and highly fractionated I-type granites. The calc-alkaline I-type amphibole-bearing granites (Group I) yield crystallization ages of ca. 317–315 Ma, and exhibit depletions in HFSEs and enrichments in LILEs with no to slight Eu anomalies and low zircon saturation temperatures, indicating that the formation of these granites may be closely related to the subduction of the Junggar oceanic slab. The Group II granite porphyries (ca. 312 Ma) contain negligible amphibole, and are characterized by evolved SiO2 but low zircon saturation temperatures with sharply negative Eu, Ba, Nb, Ta, Sr, P and Ti anomalies, belonging to highly fractionated I-type granites, and were probably produced in a tectonic transition from compressional to extensional setting. In contrast, the latest Carboniferous (ca. 304–298 Ma) alkaline A-type granites (Group III) are amphibole-absent, and are similar to Group II granites in major element compositions, but exhibit higher zircon saturation temperatures, indicating that they probably resulted in a back-arc extensional setting triggered by roll-back of the subducting Junggar oceanic slab since ca. 310 Ma. In combination with regional geology and re-interpretation of previous data, a multi-stage subduction-accretion model is suggested to account for the Late Palaeozoic tectonic evolution of the southwestern CAOB. This model can plausibly interpret the differences in duration of subduction between the northern and southern domains of West Junggar and the coexistence of A-type granites with subduction-related sanukites in the SWJ during Carboniferous to Permian. [ABSTRACT FROM AUTHOR]

The southern boundary of the high level, discordant, Devonian Strathbogie batholith in central Victoria includes two near-linear sections that strike east–west, and one north–south. Field mapping has delineated the 100 km southern boundary with 2200 waypoints taken where granite and hornfels are within 10 m of one another. There is 790 m of topographic relief along the southern boundary and, where the mapping is overlain on contours, there are intervals that reflect a steep-dipping contact and others that reflect near-horizontal contacts. Of the latter, some reflect the granite roof and others the floor. Complementary evidence from mineralogic and textural data indicates a strong correlation between the interpreted roof of the granite and the abundance of tourmaline, aplite and pegmatite. When combined, the roof and floor intervals indicate a batholith thickness up to 350 m; nowhere along the southern boundary can a thickness of 1 km be demonstrated. Along the southern boundary, at least, the batholith shape is a thin, tabular and extensive composite granite sheet analogous to a pizza rather than a pipe. The roof of the granite is nearly horizontal in both east–west and north–south sections, and the plateaux today are close to the batholith roof. On regional and local scales, granite emplacement was determined by pre-existing anisotropies, such as master joint sets, across which the propagation of magma-filled fractures (granite sheets) was arrested. The emplacement records a fine balance between magma pressure, and the interplay of lower confining (overburden) pressures and pre-existing anisotropies that also facilitated roof uplift. The opportunistic magmas used the slightest variations of those parameters. This interpretation of the Strathbogie batholith matches examples in the Himalaya and Chilean Andes but differs markedly from the portrayal of very large batholiths beneath Cu–Au porphyry systems. The boundary of the Strathbogie batholith can be mapped in moderately outcropping terrain to an accuracy of 10 m or better. Steep intervals of the boundary are interspersed with near-horizontal intervals that delineate the granite floor and roof along the 100 km of the southern boundary. The batholith, at least near its southern boundary, comprises near-horizontal sheets of <500 m aggregate thickness. The boundary determined by geophysics is adequate for regional studies but has been misleading in three-dimensional interpretations. [ABSTRACT FROM AUTHOR]

The treatment of porphyry copper ores which are considered an important source of non-ferrous and precious metals requires the development of high-efficient technologies for metal extraction ensuring a low impact on the environment. The goal of the present work was to study the feasibility of a biohydrometallurgical approach for the processing of Kajaran porphyry copper-molybdenum ore as no attempt was done previously for microbiological processing of the mentioned ore. Sulfide and oxide ore samples used for bioleaching tests contained 0.63 and 0.77% copper, 1.81 and 1.55% iron, and 0.14 and 0.023% molybdenum, respectively. The experiments were carried out in 250 ml flasks under shaking conditions. Indigenous and adapted bacterial consortia 'Kashen' and 'Kavart' were used for bioleaching of ore samples. The objectives of the study were to investigate the influence of particle size (PS), pulp density (PD), and adaptation of the bacterial cultures to the process of copper extraction. The composition of feed material and leaching residues from bioleaching experiments were characterized by geochemical, mineralogical, and particle analyses. As a result, nearly complete bioleaching of the sulfide and oxide ores could be achieved after the optimization of the experiments. The particle analyses showed an enhanced liberation of chalcopyrite particles out of the intergrown ore under bioleaching conditions compared to the abiotic controls and hence an improved Cu solubilization under bioleaching conditions. [ABSTRACT FROM AUTHOR]

Granitoid intrusions of Zagros orogenic and metallogenic belt were mainly emplaced during the Jurassic-Cretaceous and Upper Eocene – Pliocene along the Sanandaj-Sirjan Zone (SaSZ) and Urumieh-Dokhtar magmatic Arc (UDMA), respectively. The present work tried to answer the question of whether or not there are fundamental differences in magmatic systems of Mesozoic versus Cenozoic intrusions of Zagros orogen resulting in the lack of porphyry mineralization in SaSZ compared with the widespread occurrence of porphyry-bearing intrusions in the UDMA. Characterizing the geochemical features of six major granitoid intrusions in the SaSZ (Alvand, Almogholagh, Aligoodarz, Boroujerd, Dehno, and Kolah-Ghazi) show they mostly represent low to high-K calc-alkaline and peraluminous magmatic suite, which is analogous to those reported previously for the UDMA porphyry Cu intrusions. However, the SaSZ intrusions are characterized by extremely low Sr/Y contents, distinct negative Eu anomalies, and less fractioned HREE patterns with OIB signature in the less fractionated samples indicating a source dominated by melting of subcontinental lithosphere mantle. This study proposed that the inception of Cenozoic flat slab subduction followed by dehydration melting of ~ 29 Ma of metasomatized subcontinental lithospheric mantle (SCLM) during the continuous stages of continental-continental collision has a decisive role in magmatic change to a more hydrous and oxidized nature. These processes provided unique conditions for increasing metal fertility of these Miocene intrusions compared to those of older Mesozoic igneous activities in the Zagros orogenic and associated metallogenic belt. [ABSTRACT FROM AUTHOR]

Post-collisional K-rich magmatic rocks of the Qinghai–Tibet Plateau provide important information for understanding the continental collision and uplift of this plateau during the Cenozoic. However, the source of these K-rich rocks is still debated, and limited investigations have been conducted in the western Kunlun Mountains (WKM) in the northwestern margin of the plateau. In this paper, we present geochemical, geochronological, and Sr–Nd–Hf isotope data for Quanshuigou post-collisional K-rich igneous rocks from the WKM. Geochronological results show that these rocks were emplaced during two stages: (1) ca. 5.3 Ma, as an intrusive suite of granite porphyries; and (2) ca. 4.8 Ma, as a suite of shoshonites. These rocks are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs), and depleted in heavy rare earth elements (HREEs) and high-field-strength elements (HFSEs). Compositions of the granite porphyries classify these rocks as high-K calc-alkaline peraluminous A-type granites. Combining the negative zircon εHf(t) values (−6.9 to −1.1) with Hf crustal model ages (TDM2) of 1.16–1.53 Ga and negative εNd(t) values (−5.31 to −4.96) with two-stage Nd model ages (TDM2) of 1.22–1.46 Ga, these signatures suggest that the granite porphyries most probably originated from partial melting of thickened lower crust with limited input of mantle-derived magmas. In contrast, the shoshonites have low SiO2 contents (50.84–53.94 wt.%), relatively high Mg# values (50–57), and εNd (t) values ranging from −6.18 to −5.34, with single-stage Nd model ages (TDM1) of 0.97–1.02 Ga. Our analyses show that the parental magma of the shoshonites probably formed by partial melting of EMII-type lithospheric mantle, with the addition of subducted and recycled oceanic sediments. Hence, we conclude that these granite porphyries and shoshonites formed in a post-collisional, extension-related geodynamic setting and that the melting was probably triggered by motion on the Altyn Tagh strike-slip fault system. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt (CAOB) is among the world's largest Phanerozoic accretionary collage systems and hosts one of the three best-known porphyry metallogenic domain. Relatively few Devonian porphyry Cu (±Au) deposits (such as Oyu Tolgoi, Lailisigao'er, Halasu, Yulekenhalasu, etc) have been found in the CAOB, and the geological characteristics, fluid evolution and metallogenesis of Devonian porphyry Cu deposits are still uncertain. In this work, we undertake a fluid inclusion and isotopic study of the Xiaotuergen Devonian porphyry Cu deposit and present a comprehensive analysis of the ore-forming fluids to better understood Devonian porphyry deposits in the CAOB. The Devonian porphyry copper (±gold) deposits in the CAOB formed during the Early and Late Devonian (366–412 Ma) and have two peaks (375 Ma and 405 Ma). The Xiaotuergen porphyry Cu deposit, located in the Altay orogenic belt, Xinjiang, NW China, is mainly hosted by an Early Devonian granodiorite porphyry. The ore-forming fluids of the main copper mineralization stages (II and III) in Xiaotuergen were characterized by high to intermediate temperatures (190–320°C) and low to intermediate salinities (3.5–15.7 wt.% NaCl eqv.), similar to those of other the Devonian porphyry copper (±gold) deposits in the CAOB (T = 120–500°C, salinities = 0–21.7 wt.% NaCl eqv. and 33.5–51.0 wt.% NaCl eqv.). The temperatures and salinities of the ore-forming fluids changed, and phase separation might have been one of the important factors in the precipitation of chalcopyrite and pyrite. The Devonian porphyry copper (±gold) deposits in the CAOB have similar hydrogen and oxygen isotope characteristics, and the ore-forming fluids were dominated by magmatic fluids, with some minor contributions from meteoric water. The coexistence of CO2-bearing fluid inclusions with aqueous fluid inclusions in stage III suggests that fluid phase separation occurred at pressures of 110 to 320 bar (depths of 0.4–1.3 km). The formation depths of the Xiaotuergen deposit are shallower than those of the Lailisigao'er Cu deposits (palaeodepths of 1.7–2.2 km). The total sulphur value in the Xiaotuergen deposit is +12.2‰, indicating that the sulphur could have originated from crust. The δ34SV-CDT values of the most Devonian porphyry copper (±gold) deposits in the CAOB are concentrated near 0 ± 7‰, indicating a homogeneous sulphur source and derivation of sulphur from deep-seated magmas. [ABSTRACT FROM AUTHOR]

Preservation of pre-Cenozoic porphyry Cu deposits requires geological events that bury the deposits before significant exhumation. Burial may be due to basin development over the top of the porphyry system or to burial beneath thrust sheets. The porphyry Au–Cu deposits in the Cadia district of central New South Wales underwent both events, and thus this metal-rich part of the crust survived the overprinted tectonic events that shaped eastern Australia. The Cadia porphyry Au–Cu deposits are associated with the Upper Ordovician to lower Silurian Cadia Intrusive Complex emplaced into the Upper Ordovician to lower Silurian Forest Reefs Volcanics and Middle Ordovician Weemalla Formation during the final phase of Macquarie Arc magmatism. Published stratigraphic evidence suggests west-northwest-striking faults influenced stratigraphic facies and thicknesses in the Forest Reefs Volcanics. Generally north- to east-northeast-striking faults that developed early in the district's history are likely a product of exhumation of the porphyry Au–Cu deposits and their host rocks during and after the Benambran Orogeny. Alteration halos of several of the porphyry Au–Cu and skarns were exhumed at this time. Later during the Silurian (Wenlock to early Ludlow), the partially exhumed porphyry systems were buried beneath sediments, correlated with the Waugoola and Mumbil groups, in a rift–sag basinal sequence deposited initially in local fault-bounded basins that must be connected regionally to formation of the Cowra and Hill End troughs to the west and east, respectively. This basin geometry was controlled by the reactivation of the extant basement faults. Shortening of the Silurian sedimentary succession during younger Paleozoic orogenies was accommodated in thin-skinned fold and thrust faults forming a complex network of bedding-parallel detachments, ramps and anticlines that are linked to steeply dipping reverse and oblique-reverse slip faults in the underlying Forest Reefs Volcanics and the Cadia Intrusive Complex. The world-class porphyry Au–Ci deposits were initially exhumed for a relatively brief interval during the early Silurian as a result of the Benambran Orogeny. The porphyry Au–Cu deposits were subsequently buried beneath Silurian sediments of the Waugoola Group accumulating in rifted basins formed during the Wenlock and Ludlow epochs of the Silurian, with sedimentary deposition continuing into the Pridoli (latest Silurian) in the lower part of the Mumbil Group. The Silurian basin was inverted with thin-skinned fabrics in the Silurian sedimentary rocks and thick-skin fabric localised along pre-existing faults, burying the deposits. [ABSTRACT FROM AUTHOR]

The Northparkes district, central New South Wales, hosts several economic Cu–Au deposits associated with discrete, thin, porphyry intrusive complexes emplaced in the Late Ordovician during formation of the Macquarie Arc. The recently discovered Two-Thirty Cu–Au–(Mo) prospect is a mineralised magmatic–hydrothermal breccia complex that is hosted by the moderately east-dipping Goonumbla Volcanic Complex on the western limb of the Milpose Syncline ∼15 km south of the Northparkes porphyry district. Generation of the magmatic–hydrothermal breccia complex is interpreted to be related to the 448.0 ± 4.4 Ma emplacement of the Two-Thirty porphyry. However, Re–Os dating of molybdenite from the breccia complex indicates a potential for a ca 440 Ma mineralising event that has similar timing to economic porphyry mineralisation in the Northparkes district. The discovery of the Two-Thirty prospect has important implications for exploration in the Northparkes district and the broader Macquarie Arc. Two-Thirty is only the second known occurrence of magmatic-hydrothermal breccia-hosted mineralisation discovered within the Macquarie Arc, with the other being Cadia Quarry. Mineralisation at Two-Thirty is potentially older than the Northparkes and Cadia deposits, and younger than the epithermal and calc-alkaline deposits at Cowal, Marsden and Ridgeway. The Two-Thirty is a polyphase magmatic–hydrothermal breccia complex that hosts Cu–Au (Mo). The Two-Thirty is the first significant breccia-hosted mineralisation found in the Northparkes district. U–Pb zircon crystallisation ages of the causative intrusion at Two-Thirty pre-date mineralisation at Northparkes. Re–Os dates of molybdenite from the Two-Thirty breccia complex are coeval with syn-mineralisation at Northparkes, supporting the model of periodic release of melts and fluids from underlying magma chambers during the formation of porphyry mineralisation in the Northparkes district. [ABSTRACT FROM AUTHOR]

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery was used to identify argillic, phyllic and propylitic alteration zones and mapping geological structural features for porphyry copper exploration in the Kacho-Mesqal zone, Urumieh- Dokhtar Magmatic Arc, Iran. The image processing techniques such as specialised band ratio, Selective Principal Component Analysis (SPCA), and Spectral Angle Mapping (SAM) image processing methods were implemented to the visible and near-infrared and shortwave infrared bands of ASTER. Results indicate that the argillic alteration zone is broadly distributed in the granodiorite intrusion, andesitic rock, tuff breccia and ignimbrite. Phyllic alteration is mainly mapped associated with sandstone and some parts of andesitic lithology. Propylitic alteration zone is identified in andesite, sandstone, shale and marl, dacite to rhyodacite, andesite-basalt, tuff and andesite lava and granodiorite intrusion. The fracture density map shows that the argillic alteration is mostly abundant in the high-density fracture zone, whereas propylitic and phyllic zones are located in moderate to low-density fracture zones. Consequently, high potential zones for copper mineralisation in the study area are identified within the high to moderate fracture density zones associated with argillic and assemblage of argillic, phyllic and propylitic alteration zones in granodiorite and andesite units. [ABSTRACT FROM AUTHOR]

This research presents a new method for assessing magmatic fertility using the portable X-ray fluorescence spectrometer (pXRF) in altered rocks from porphyry terranes. A study of Northparkes and global Cu--Au porphyries highlighted low Zr and Y trends associated with mineralising intrusions. Zircon saturation occurs at low Zr concentrations owing to low-temperature crystallisation depressed by high dissolved H2O in the melt. Yttrium depletion indicates hydrous magmatic conditions that cause hornblende to crystallise early. Previously geochemical differentiation of hydrous, potentially ore-forming (fertile) porphyries has relied on ratios of Sr/Y and Sr/MnO from geochemical and/or pXRF analysis of least altered rocks. Strontium is highly mobile and limits its use in altered terranes. Finding samples in porphyry terranes where Sr can be demonstrated to be retained is difficult given the ubiquity of alteration associated with porphyry emplacement. This precludes the widespread use of pXRF, as quantitative assessment of alteration is beyond the capabilities of pXRF technology. Using immobile elements overcomes issues with alteration and provides more reliable indicators of magmatic fertility. Using a systematic pXRF workflow, plots of Zr vs Y and Zr*Y vs Al2O3/TiO2 were successful in identifying 100% of the mineralising intrusions in the Northparkes intrusive complex and provide an indication of magmatic fertility and a proxy for melt hydration state. The ratios of Zr/Nb vs Y/Nb are insensitive to alteration including weathering and are indicative of evolution and dissolved H2O content of magmatic sources. Moving from bivariate plots to ratio plots shifts the data into a real-number space and provides a linear function to assess against magmatic fertility. Application of the fertility indicators to a regional dataset from New South Wales highlights areas of known porphyry mineralisation indicating that the method has the potential to be a useful indicator of fertility beyond the scope of the pilot study. The fertility of porphyry intrusions is directly related to their dissolved H2O content and oxidation state. High dissolved H2O content in magmas causes early crystallisation of hornblende, and temperature depression. As a result Zr saturation occurs at low Zr concentrations that results in depletion of Y and the MREE in hydrous rocks compared with normal arc rocks. Magmatic fertility can be rapidly and cheaply assessed in the field using Zr and Y concentrations from pXRF analyses. The use of immobile elements facilitates magmatic fertility assessment in altered rock, which was previously impossible owing to the use of mobile elements Sr and MnO. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate effects of silicate (SIL) supplementation on growth performance, nutrient digestibility, organ weight, immune traits, fecal microbiota, rectal temperature, and diarrhea score in weaning to growing pigs with challenged lipopolysaccharide (LPS). In experiment 1, a total of 72 piglets [(Landrace x Yorkshire) x Duroc] with initial body weight (BW) of 7.53 ±0.1 kg were used in 14 weeks. Treatment groups: (1) Basal diet (CON), and (2) Basal diet+ 0.1% silicate (SIL). In experiment 2, after reaching an average BW of 28.12 ±0.79 kg at end of this experiment, 24 piglets in each treatment (12 pigs per treatment and 2 pigs per pen) were challenged with 100 µg/kg LPS. In experiment 1, SIL diets improved (P <0.05) growth performance, crude protein (CP) digestibility and reduced (P <0.05) NH3 emission compared to CON diet. In experiment 2, after piglets were fed SIL diets, numbers of white blood cells (WBCs) such as WBC, neutrophil, monocyte, and lymphocyte were increased (P <0.05). SIL diets decreased (P <0.05) cortisol level, Escherichia coli count, diarrhea incidence, and rectal temperature compared to CON diet. [ABSTRACT FROM AUTHOR]

Four economic porphyry Cu–Au deposits and several prospects have been investigated in the Northparkes district, part of the Ordovician to early Silurian Junee–Narromine Belt of the Macquarie Arc, New whole-rock geochemical data from the Northparkes porphyry Cu–Au district, NSW, indicate that the mineralising intrusive complexes exhibit distinct arc signatures that are transitional from high-K calc-alkaline to silica-saturated alkalic. Based on ratios of Sr/Y vs Y (e.g. Sr/Y > ∼20 and Y < ∼17 ppm) the mineralising intrusions are interpreted to have crystallised from fractionated hydrous melts indicating the suppression of plagioclase crystallisation in favour of hydrous mineral phases. This interpretation is supported by listric-shaped rare earth element curves and the presence of primary hornblende phenocrysts indicating elevated magmatic water contents. There is an association of mineralising intrusions with a low Zr trend both in the mineralised Northparkes district intrusive rocks and in mineralised porphyry-related intrusive rocks globally. A newly developed fertility indicator ratio Zr/Y ∼10% is more accurate at identifying the mineralised rocks at Northparkes than the conventional Sr/Y vs Y fertility indicator diagram, successfully identifying 92% of the mineralising intrusions, mainly owing to the fact that it is less affected by hydrothermal alteration. The insensitivity of Zr–Y to alteration makes this indicator a useful new tool that may lead to enhanced probabilities for future discoveries in the Northparkes district, broader Macquarie Arc and altered rocks globally. Mineralising intrusions in the Northparkes district have distinct Zr vs Y concentrations. The Zr vs Y indicator of magmatic fertility is less sensitive to alteration than Sr-based indicators. The Zr vs Y magmatic fertility indicator identified at Northparkes is not unique and identifies mineralising intrusions in other porphyry fields. [ABSTRACT FROM AUTHOR]

In this paper, the main and interaction effects of chemical reagent (collector and frother) dosages on the copper flotation performance using response surface methodology in design expert software were examined and the optimized dosage of reagents were specified. Then, in order to increase copper grade and recovery at industrial rougher flotation cells of the Miduk copper concentrator, Iran, distribution patterns of chemical reagents in suggested optimum conditions were investigated. A central composite design with three levels and five variables was employed to model and optimize the laboratory batch scale flotation process. The effect of dosages of Z11 (0–10 g/t), Flomin C4132 (14–34 g/t), A3477 (5–15 g/t) as collectors, AF65 (5–15 g/t) and MIBC (4–12 g/t) as frothers was studied. Forty-eight batch rougher flotation experiments (pH 11.5) for Miduk porphyry copper ore consisting of 0.9% Cu were conducted at different conditions using a bench scale Denver flotation cell with 3 L capacity. Second order response functions were generated for both the Cu grade and recovery models, as metallurgical indicators. These model equations were optimized using quadratic programming so as to maximize Cu grade and recovery within the experimental range studied. The main effect of all reagents dosages and the interaction of the Z11-Flomin C4132, Z11-A3477, and A3477-MIBC dosages had a significant impact on both recovery and grade. The optimum reagents dosages were found to be 5 g/t Z11, 34 g/t C4132, 5 g/t A3477, 15 g/t AF65, and 8 g/t MIBC. Maximum recovery of 91.4% and grade 8.13 were achieved under optimal conditions. Additionally, verification experiments at optimum conditions proposed by the models were carried out to specify the validity and adequacy of the predicted models. Based on the industrial rougher circuit tests results, distribution patterns of 75%-0%-25% and 50%-25%-25% were selected as the best distributions of collectors and frothers in mentioned conditions, respectively. The copper recovery and grade improved about 2% and 1.8%, respectively, via the use of optimized stage addition of reagents. [ABSTRACT FROM AUTHOR]

Large porphyry Cu-Au deposits are associated with Early Miocene intrusive rocks in Tethyan belt, discovered along Chagai magmatic arc in Western Pakistan, adjacent to Southeast Iran. Two types of rocks were discriminated as granodiorite and monzodiorite from Saindak area. The granodiorites are associated with regional large Cu-Au mineralization, while the monzodiorites are mostly ore-barren. LA-ICP-MS U-Pb dating yielded weighted mean 206Pb/238U ages of 22.16–24.2 Ma for granodiorites and ca. 22.6 Ma for a monzodiorite. These intrusive rocks in the Saindak area are all calc-alkaline rocks, with enriched LILEs and depleted HFSEs, and without Eu negative anomalies. The felsic granodiorites are characterized by high Sr contents and Sr/Y ratios, with intermediate to high (La/Yb)N ratios that identify them as typical high-silica adakites. In contrast, the basaltic-andesitic monzodiorites are just normal arc-related rocks, showing less fractionated REE patterns than the granodiorites, with systematically lower LREE and higher MREE and HREE. Low K2O/Na2O ratios and decoupled Sr/Y-(La/Yb)N ratios indicate the characteristics of slab-derived adakites for the granodiorites, most likely originated through partial melting of the subducted Neotethys oceanic crust beneath Eurasian continent followed by subsequent mantle interaction. The almost simultaneously melting of subcontinental lithospheric mantle induced by dehydration of Neotethys plate gave rise to the formation of the barren monzodiorites. These intrusive rocks in the Saindak area are characterized by similar Sr-Nd-Pb isotopes with high 87Sr/86Sri ratios, slightly negative εNd(t) values and radiogenic Pb isotopes, plotting in the field between the MORB and EM-II mantle endmembers or the Average Cadomian Lower Crust, suggesting subducting sediments or old continental crustal materials have contributed into the compositions of these rocks by source enrichment or crustal contamination. The slab-melting derived adakite is favourable for regional massive Cu-Au mineralization in the Saindak area. [ABSTRACT FROM AUTHOR]

This paper endeavours to evaluate the structural controls of porphyry copper mineralization in Dehaj area, Central Iran, using numerical techniques, an aim for which the various data types including the location of mineral deposits, stream sediment geochemical data and faults were employed. Initially, classical statistics and the concentration-area (C-A) fractal methods were applied to identify mineralization-related geochemical anomalies, revealing the superiority of fractal technique over the traditional methods employed. In addition, a rose diagram portraying the distribution of mineral locations was compared to the distribution and trends of faults using fractal and fry analyses, showing that the spatial pattern of porphyry copper deposits is closely linked to NW- and E-trending faults. In other words, the aforementioned structural trends were plausibly the chief geographical directions controlling the mineralization. The results of this study suggest that NW- and E-trending faults have plausibly operated as corridors for the transportation of ore-bearing fluids. [ABSTRACT FROM AUTHOR]

We evaluated imaging alteration associated with porphyry copper style mineralisation using aeromagnetic data in the Highland Valley Copper (HVC) district as part of the Natural Sciences and Engineering Research Council of Canada (NSERC) and Canada Mining Innovation Council (CMIC) Footprints project. The first step of the investigation involved construction of a 3D geological model based on surface and regional information, and petrophysical data of the host rocks. From the petrophysics, it was observed that hydrothermal alteration affected the magnetic susceptibility of some batholithic host rocks at HVC, and low susceptibility values were associated with the altered rocks. From this observation, an alteration index was devised, differencing, based on the magnetic susceptibility, between unaltered and altered batholith host rocks. Three-dimensional inversions were conducted using geological constraints obtained from surface and borehole geology as well as physical property data. Then the alteration index methodology was tested using 3D inversions and residual models within five overlapping blocks covering portions of the batholith. The indices inferred from inverted susceptibility were compared to surface mapped alteration. For some felsic facies of the batholith, the alteration index derived from inverted magnetic susceptibility corresponds to the mapped alteration and delineates the known porphyry Cu system district. However, it is not true for others where alteration was less magnetite-destructive and more focused in structures. [ABSTRACT FROM AUTHOR]

Hyperspectral remote sensing is economical and fast, and it can reveal detailed spectral information of plants. Hence, hyperspectral data are used in this study to analyse the spectral anomaly behaviours of vegetation in porphyry copper mine areas. This analytical method is used to compare the leaf spectra and relative differences among the vegetation indices; then, the correlation coefficients were computed between the soil copper content and vegetation index of Quercus spinosa leaves at both the leaf scale and the canopy scale in the Chundu mine area with different geological backgrounds. Lastly, this study adopts hyperspectral data for the level slicing of vegetation anomalies in the Chundu mine area. The results showed that leaf spectra in the orebody and background area differed greatly, especially in the infrared band (750 nm – 1300 nm); moreover, some indices like the normalized water index (NWI) and normalized difference water index (NDWI) of Quercus spinosa and Lamellosa leaves are sensitive to changes in the geological background. Compared with the canopy, the leaf hyperspectral indices of Quercus spinosa in Chundu can better reflect soil cuprum (Cu) anomaly. In addition, the NWI and NDWI of Quercus spinosa are significantly correlated with the soil Cu content at both the canopy scale and the leaf scale. Consequently, the results of the vegetation anomaly level slicing can adequately reflect the plant anomalies from ore bodies and nearby areas, thereby providing a new ore-finding method for areas with a high degree of vegetation coverage. [ABSTRACT FROM AUTHOR]

This study investigates the prospectivity for porphyry Cu mineralisation of the early Paleozoic Loch Lilly-Kars Belt, which follows the southern margin of the Paleoproterozoic Broken Hill (Willyama) Inlier in western New South Wales, Australia. The belt is thought to have resulted from the 515–510 Ma collision of a volcanic passive margin and an intra-oceanic island arc above a west-dipping subduction zone, with subsequent post-collisional magmatism. To identify fertility signals of selected magmatic intrusive rocks, we combined whole-rock analyses with in-situ zircon trace-element and isotopic measurements. Data reveal that both Cambrian (ca 496 Ma) and Devonian (ca 393 Ma) intrusive suites are present in the Loch Lilly-Kars Belt. Cambrian dioritic rocks are largely non-fertile for porphyry Cu mineralisation, whereas Devonian monzodiorites and monzonitic porphyries carry strong fertility signals that include high whole-rock Sr/Y (>35) and V/Sc (>10) values, associated with the occurrence of equant, stubby zircons showing relatively constant Eu/Eu* values without any significant Eu anomalies. Although only few samples were analysed and more intensive exploration is required, the results of this study indicate significant potential for porphyry Cu mineralisation in this poorly known belt. [ABSTRACT FROM AUTHOR]

This study uses remote sensing image-processing to enhance recognition of areas with mineral abundance halo, which can be associated with porphyry mineralisation of the Urumieh-Dokhtar Magmatic Belt (UDMB) in western Yazd. Granitoid intrusions of Oligocene-Miocene age in UDMB hosts the most important Porphyry Copper Deposits (PCDs) of Iran such as Darezereshk and Aliabad PCDs. Diagnostic spectral absorption features of six shortwave infrared (SWIR) and three visible and near-infrared (VNIR) bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were applied to determine the alteration minerals and their abundance. In this research reflectance data from various representative alteration types throughout the study area were measured by the FieldSpec-3 spectroradiometer and applied for mapping minerals. Different remote sensing analytical techniques, including the Principal Component Analysis (PCA), band ratio, relative absorption band depth, and MTMF, were applied to enhance mapping the alteration minerals. Field works including rock sampling, petrography and field spectroradiometer followed up the alteration mapping. Field observation implies that, the vein-type mineralisation above the cupola of this porphyry system is preserved in the western part, although it was eroded in the eastern area. Consequently, PCDs potential is expected to be higher in the western area. [ABSTRACT FROM AUTHOR]

The Siah Kamar porphyry Mo deposit is the newly discovered deposit of this type in the Neo Tethys-related Urumieh–Dokhtar magmatic arc, northwest Iran. Mineralization occurs as stock-work quartz–molybdenite and mono-mineralic molybdenite veinlets within the porphyry quartz-monzonite stock and the country rocks, accompanied by locally scattered later-stage and cross-cutting quartz-chalcopyrite-pyrite veinlets in the trachy-andesite and trachy-basalt country rocks. U–Pb zircon geochronology of the porphyry stock yielded Early Oligocene dates of 32.7 ± 0.4 to 30.9 ± 0.4 Ma (at 2σ level). The Th/U ratios of the zircons range between 0.48 and 0.77, and they possess initial εHf(t) values of 3.2 to 12.1, which may suggest a dominant mantle source for the magma. Molybdenite separates yielded rhenium contents between ~10 and 41 ppm (average ~26 ppm, n = 4) and slightly younger Re–Os ages compared to the porphyry stock, ranging from 29.1 ± 0.2 to 28.1 ± 0.2 Ma (at 2σ level). The Siah Kamar porphyry Mo deposit is nearly temporally coeval with the Haft Cheshmeh porphyry Cu deposit and the vein-type Cu–Mo–Au mineralization in the Qarachilar area, corresponding to the second porphyry Cu–Mo mineralization epoch in NW Iran. However, it is younger than the majority of the porphyry Cu deposits in the southern Lesser Caucasus and only shows temporal correlation with the Paragachay and first-stage Kadjaran porphyry Cu deposits. Moreover, it is older than all the porphyry Cu–Mo systems across the central and south-eastern parts of the Urumieh–Dokhtar magmatic arc, except the Bondar Hanza deposit, which is nearly coeval with the Siah Kamar porphyry Mo deposit. All these data reveal an old to young trend along the UDMA and the porphyry Cu belt of Iran, further testifying to the diachronous and later closure of the Neo-Tethyan oceanic basin in central and SE Iran. [ABSTRACT FROM AUTHOR]

The mechanisms triggering the emplacement of Cretaceous magmatic rocks related to Neo-Tethyan subduction in the southern Lhasa subterrane (SLT) remain controversial because geochronological, geochemical, and isotopic data from the Cretaceous magmatic rocks in the western portion of the SLT are lacking. This paper provides the first report indicating that the Dazhuqu hornblende gabbro and Xietongmen granite porphyry were generated in the Late Cretaceous (ca. 100 Ma and ca. 68 Ma, respectively) in the western portion of the SLT. The Dazhuqu hornblende gabbro is characterized by high MgO, Na2O, Cr, Co, and Mg# values, enrichment in light rare earth elements (LREEs) and large ion lithophile elements (LILEs), and depletion in high field strength elements with no Eu anomalies. The Xietongmen granite porphyry displays high SiO2, low MgO, Mg#, Cr, Co, and Ni, enrichment in LREEs and LILEs, flat heavy rare earth element (HREE) patterns and negative Eu anomalies. Zircons from the Dazhuqu hornblende gabbro and Xietongmen granite porphyry display high positive εHf(t) ranges from 11.79 to 14.91 and from 9.05 to 12.38, respectively. The Dazhuqu hornblende gabbro was produced by the partial melting of 12–15% garnet peridotite in the depleted mantle that was metasomatized by fluids released from the dehydrating subducted Neo-Tethyan oceanic slab. This magma was then emplaced at an upper crustal depth of 5.3–7.0 km. The Xietongmen granite porphyry was generated by the partial melting of underplated basaltic crust during the subduction of the Neo-Tethyan oceanic crust and formed in the presence of pyroxene, plagioclase, and minor hornblende in its magmatic source. In combination with previously published data from Cretaceous magmatic rocks in the SLT, our data suggest that the petrogenesis of the Dazhuqu hornblende gabbro was related to flat or low-angle slab subduction of the Neo-Tethyan oceanic crust during 109–97 Ma and that the formation of the Xietongmen granite porphyry was related to lithospheric delamination in the western portion of the SLT after ca. 68 Ma. [ABSTRACT FROM AUTHOR]

The northern Lesser Xing'an Range in NE China hosts many gold deposits. However, genesis and tectonic background for the mineralization remain unclear. The newly discovered Yongxin gold deposit in this region provides a good example for understanding the related issues. Two economic orebodies have been recognized at Yongxin and they are mainly hosted in the hydrothermal breccias. Zircon U–Pb ages of granite porphyry and diorite porphyry are 119.3 ± 0.7 Ma and 119.9 ± 0.6 Ma, respectively. These data provide constraints to the upper limit of ore-forming age. The δ34S values of pyrite from orebodies range from 2.3‰ to 5.1‰. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of the pyrite are of 18.126–18.255, 15.492–15.537 and 37.880–38.019, respectively. The δ18OH2O and δD values of ore-forming fluids range from −12.5‰ to 1.8‰ and from −124.8‰ to −102.1‰, respectively. The REE compositions of gold-bearing pyrite are similar to those of the volcanic rocks of the Longjiang formation, diorite porphyry and granite porphyry. The combined geological, geochronological and geochemical characteristics of the Yongxin gold deposit indicate that the ore-forming materials were likely sourced from the volcanic rocks of the Longjiang formation, diorite porphyry and granite porphyry, whereas the ore-forming fluids are dominated by meteoric water. The Yongxin gold deposit could be a product of the Early Cretaceous large-scale gold mineralization in northeast China which occurred in an extensional tectonic setting and were related to the rollback of the subducted Paleo-Pacific Oceanic Plate beneath the continental margin of northeast China. [ABSTRACT FROM AUTHOR]

Based on the fluid inclusion and rock sample geochemistry in Deh-Salm hydrothermal system, it is shown that uneconomic molybdenite mineralization occurred in both stockwork- and limited skarn-type alterations. Homogenization temperatures and salinities based on microthermometry data are presented for fluid inclusions from hydrothermal quartz associated with pyrite, galena, sphalerite and rare molybdenite mineralization. The data indicate that ore mineral precipitation occurred within a temperature range of 250° to > 490°C from moderate to high-salinity (9 to > 42 wt% NaCl equivalent) aqueous fluid. Two stages of hydrothermal activity characterized by high-salinity fluids (> 30 wt% NaCl equivalent) are identified; 1) relatively high-temperatures (350° to > 490°C); 2) lower temperatures (170° to 250°C). The high-salinity, high-temperature stage is interpreted to be the evidence for resurgent boiling. Dilution of these fluids by convicting meteoric water resulted in low to moderate salinity fluids, which dominated the inclusion population in quartz hosted crystals. The high-salinity, low-temperature fluid inclusions identify the residual fluids derived from boiling which happened as a result of a change in the pressure regime from dominantly lithostatic to hydrostatic conditions. Condensation and infiltration of ground waters caused major chemical variations, increasing the hydrostatic pressure, and the acid-washed processes on the system. The intense acid-washed and the intrusive rock depth is suggested to be the main reasons caused an uneconomic metal deposition in Deh-Salm system. [ABSTRACT FROM AUTHOR]

The magmatic generation for the Late Triassic-Early Jurassic (~215-200 Ma) and Early Cretaceous-Late Cretaceous (~108-79 Ma) post-collisional granites in the Sanjiang Tethys orogeny remain enigmatic. The Xiuwacu complex, located in the southern Yidun Terrane, consists of biotite granite with a weight mean 206Pb/238U age of 199.8 ± 2.5 Ma, aplite granite of 108.2 ± 2.3 Ma, monzogranite porphyry of 80.8 ± 1.0 Ma, and diorite enclaves of 79.2 ± 0.9 Ma and 77.9 ± 0.8 Ma. The Late Triassic biotite granites show I-type granite affinities, with high SiO2 contents, high Mg# values, high zircon δ18O values, and negative whole-rock ƐNd(t) values, indicating a predominant ancient crustal source with the input of juvenile materials. Their fractionated REE patterns and concave-upward middle-to-heavy REE patterns require garnet-bearing amphibolite as the melt source. The Cretaceous highly fractionated aplite granites and monzogranite porphyries have relatively high SiO2 contents, high (Na2O + K2O)/CaO ratios, high zircon δ18O values, and enriched whole-rock Sr-Nd isotopic signatures, suggesting that their parent magmas were likely originated from the ancient middle- to lower crust. Their significant negative Eu anomalies and obvious depletions in Nb, Sr, and Ti demonstrate that the Cretaceous granitic magmas had experienced more fractionation than the Late Triassic felsic magmas. The Late Cretaceous diorite enclaves show low SiO2 contents, high Mg# values, and high zircon δ18O values, suggesting that they were probably derived from the partial melting of subcontinental lithospheric mantle enriched by the Late Triassic subduction. The Late Triassic-Early Jurassic and Early Cretaceous-Late Cretaceous magmatism witnessed the post-collisional setting and intraplate extensional setting in response to the slab break-off and lithospheric-scale transtensional faulting, respectively. The partial melting of subduction-modified lithospheric mantle or/and residual sulphide cumulates within the lower crust during the origination of Late Cretaceous magmas could have provided metals for the formation of Xiuwacu deposit. [ABSTRACT FROM AUTHOR]

Abundant evidence points to the Cretaceous crust-mantle interaction and plate subduction in the Gan-Hang Tectonic Belt (GHTB), southeastern China, but the evolutionary process remains poorly constrained. Here we conduct a comprehensive study on Daqiaowu granitic porphyry and diabase dikes in the eastern GHTB, in conjunction with previous studies on simultaneous felsic and mafic rocks along the GHTB, to demonstrate their petrogenesis and geodynamic evolutionary process. The Daqiaowu granitic porphyry (125 Ma), as well as the coeval granitic rocks, exhibits high zircon saturation temperatures, alkalis, 104*Ga/Al ratios, and Zr + Nb + Ce + Y contents, concluding a distinctive belt of the Early Cretaceous (~137-125 Ma) A-type volcanic-intrusive rocks in the GHTB. Their εNd(t) and zircon εHf(t) values gradually increased through time from approximately −9.0 to −1.0 and −10.0 to +4.0, respectively, implying increasing contribution of mantle-derived components to their formation, and hence progressively intensified crust-mantle interaction in an intra-arc rift environment (a geodynamic transition stage from continental arc to back-arc) during the Early Cretaceous. This plausibility is further supported by the Early Cretaceous Daqiaowu diabase dikes and coeval mafic rocks which exhibit arc-like magmatic signatures and were derived from mantle wedge. In contrast, the Late Cretaceous mafic rocks show ocean island basalt-like geochemical characteristics, reflecting a depleted asthenosphere mantle source. This discrepancy of mantle sources concludes that the geodynamic setting in the GHTB may have basically transferred to back-arc regime in the Late Cretaceous. Thus, the Cretaceous geodynamic evolutionary process in the GHTB can be defined as the Early Cretaceous gradually intensified crust-mantle interaction in a geodynamic transition stage (from continental arc to back-arc extension) and the Late Cretaceous back-arc extensional setting. [ABSTRACT FROM AUTHOR]

In this study, Early Cretaceous skarn deposits and genesis of their host diorite/monzodiorite porphyry in the Xuzhou-Huaibei (Xu-Huai) region, northern Anhui-Jiangsu have been discussed by detailed geochemical work. In-situ zircon U-Pb dating of the diorites related to Fe-Cu-Au deposits shows that they were formed between 131.4 ± 1.5 Ma and 130.8 ± 1.8 Ma. Geochemical data indicate a depletion of high field strength elements (HFSE) in the diorite porphyry with similarity to that of arc-related igneous rocks. The diorite porphyry was probably derived from typical arc magmas related to continental margin subduction characterized by light rare earth elements (LREEs) enrichment and HFSE depletion. REEs compositions of apatite in the diorite porphyry indicate that the dioritic magma was produced from the metasomatized subcontinental mantle by slab-derived fluids. The magma was proven to be a high oxygen fugacity; thus, it was particularly conducive to the precipitation of Fe, Cu, Au and other ore-forming elements. The δ34S values of pyrite and chalcopyrite of Fe-Cu-Au ores range from −0.2‰ to 2.8‰, indicating that the sulphur in the ore was probably derived from deep-seated magmas. Integrated with geochronological and geochemical analyses, we suggest that the Early Cretaceous igneous suites associated with Fe-Cu-Au deposits in the Xu-Huai region are related to recycling subduction of Pacific oceanic crust. [ABSTRACT FROM AUTHOR]

The Beihuaiyang Zone (BHY) is one of the most important Mo-Pb-Zn polymetallic metallogenic belts in China, and the BHY deposits are genetically and geographically associated with Cretaceous magmatic rocks. In this article, we present new zircon U-Pb ages and Hf isotope data, whole-rock major and trace-element analytical results, and Sr-Nd-Pb isotope data for the granite porphyry of the Shapinggou (SPG) Mo deposit and the quartz monzonite porphyry of the Gongdongchong (GDC) Pb-Zn deposit. The high contents of SiO2, crust-like rare-earth-element and trace element patterns, and the enriched Sr-Nd-Pb-Hf isotopic compositions indicate that both porphyries originated from crustal melting. Inherited Neoproterozoic zircons are common in both porphyries, which implies that their crustal sources were the South China Block rather than the North China Block. Whole-rock εNd(t) values (−10.8 to −9.8 for the GDC deposit, −12.9 to −12.4 for the SPG deposit) and zircon εHf(t) values (−14.3 to −11.1 for the GDC deposit, −18.4 to −13.3 for the SPG deposit) for the ore-bearing rocks are significantly higher than the values found in the widespread and older ore-barren rocks, indicating that the magma sources of the ore-bearing rocks were younger than those of the ore-barren rocks. An integrated study of the Sr-Nd-Pb-Hf isotope contents shows that these younger source rocks are similar to the gneisses found in the South and Central Dabie units, which represent the upper crust of the subducted South China Block. Given the geochemical behaviour of molybdenum, a surface enrichment process would have been an essential prerequisite for the formation of the large Mo deposit. The early Paleozoic Mo-Pb-Zn-enriched black shales, which are widespread in the upper layers of the South China Block, might have been scraped off during Triassic subduction and then transported to deep-crustal levels below the BHY, thus forming an ideal source for the ore-bearing porphyries. An upper-crustal origin for the ore-bearing magmatic rocks is also consistent with the data for most other deposits distributed in the BHY of the Dabie Orogen. [ABSTRACT FROM AUTHOR]

The Tiantang Cu-Pb-Zn polymetallic deposit in western Guangdong, South China, is hosted in the contact zone between the monzogranite porphyry and limestone of the Devonian Tianziling Formation. Orebodies occur in the skarn and skarnized marble as bedded, lenses, and irregular shapes. In this study, we performed LA-ICP-MS zircon U-Pb dating, zircon trace elements, and Hf isotopic analyses on the Tiantang monzogranite porphyry closely related to Cu-Pb-Zn mineralization. Twenty-two zircons from the sample yield excellent concordia results with a weighted mean 206Pb/238U age of 104.5 ± 0.7 Ma, which shows that the emplacement of the monzogranite porphyry in the Tiantang deposit occurred in the Early Cretaceous. The zircon U-Pb age is largely consistent with the sulphide Rb-Sr isochron ages, indicating that both the intrusion and Cu-Pb-Zn mineralization were formed during the Early Cretaceous in South China. The εHf(t) values of three inherited zircons from the monzogranite porphyry are 13.1, 11.9, and 12.9, respectively, and the two-stage Hf model ages are 1096 Ma, 1087 Ma, and 1055 Ma, respectively. Except for the three inherited zircons, all εHf(t) values of zircons are negative and have a range of −7.6 to −3.4, with the two-stage model ages (TDM2) of 1380-1643 Ma, which indicates the rock-forming materials were mainly derived from the partial melting of Mesoproterozoic to Neoproterozoic crust rocks, and probably included some Neoproterozoic arc-related volcanic-sedimentary materials. In this study, the monzogranite porphyry from the Tiantang deposit has calculated Ce4+/Ce3+ ratios of zircon ranging from 91 to 359, indicative of a more oxidized signature and significant prospecting potential for ore-related magmatism. Based on ore deposit geology, isotope geochemistry, and geochronology of the Tiantang Cu-Pb-Zn deposit and regional geodynamic evolution, the formation of Early Cretaceous magmatism and associated polymetallic mineralization in South China is believed to be related to large-scale continental extension and subsequent upwelling of the asthenosphere. [ABSTRACT FROM AUTHOR]

We report geochemical data and zircon SHRIMP U-Pb ages for Late Mesozoic granitoids from the western Zhejiang province and southern Anhui province (the WZSA region) from southeast China. In combination with published geochronological and geochemical data, the granitoids in the region can be divided into three stages: 171-141 Ma, 140-121 Ma, and 120-95 Ma. The first stage of these granitoids is mainly composed of granite porphyry and granodiorite which are similar to I-type granitoids, including having weakly negative Eu anomalies with enrichment in light rare earth elements (LREE), Rb, Th, and U. The second stage of granitoids consists of monzogranite, syenogranite, and granite with the characteristics of both A-type and I-type granitoids including strongly negative Eu anomalies; depletion of Ba, Sr, and Ti; and enrichment of K, Rb, and high field strength elements (HFSEs) (such as Th and U). The third stage of granitoids is mainly composed of granite, quartz monzonite, quartz diorite, and mafic rocks with weakly negative Eu anomalies and also enrichment in LREE, Rb, Th, U, and K. From our work, we propose a transition from compressional to extensional magmatism at ~141 Ma. Based on the geochemical characteristics of these granites and coeval mafic rocks, we propose that the formation of the A-type magmatism in the WZSA region formed as the result of lithospheric extension and asthenospheric upwelling during the Early Cretaceous. [ABSTRACT FROM AUTHOR]

We report new zircon U-Pb ages, Hf isotopic and geochemical results for the Tongling granitic plutons of Southeast China. SHRIMP U-Pb ages for the Miaojia quartz monzodiorite porphyrite，the Tianebaodan and Tongguanshan quartz monzodiorites, the Xinqiaotou granodiorite porphyry, and the Shatanjiao and Nanhongchong granodiorite are 143 ± 2, 141 ± 1 and 142 ± 1, 147 ± 1, and 145 ± 1 and 139 ± 1 Ma, respectively. Combined with previous geochronological data, our results indicate that the porphyritic rocks are older than rocks of the same type lacking porphyritic texture. Geochemically, these high-K calc-alkaline intrusive rocks are characterized by arc-like trace element distribution patterns, with significant enrichment in LILE and LREE but depletion in HFSE. Lu-Hf isotopic compositions of zircons from the high-K calc-alkaline (HKCA) rocks have εHf(t) values of magmatic 139-147 Ma zircons from −8.1 to −25.6, with two-stage model ages (tDM2) of 1.71-2.67 Ga, whereas εHf(t) values of inherited 582-844 Ma zircons range from 5.4 to −9.5, with tDM2 of 1.39-2.22 Ma, younger than tDM2 values of igneous zircon, indicating that newly formed mantle material was added to the continental crust of the Yangtze Block. Moreover, εHf(t) values of inherited zircon cores older than 1000 Ma are from −7.8 to −26, similar to magmatic zircons, and the tDM2 values are all greater than 3.0 Ga (3.16-3.75 Ga), reflecting partial melting of ancient sialic material. We conclude that the plutonic melts were derived from both the enriched mantle and the ancient crust. The HKCA Tongling intrusions coincide temporally with the J3-K1 magmatic event that was widespread in Southeast China. This igneous activity may have accompanied sinistral slip along the Tan-Lu fault due to oblique subduction of the Palaeo-Pacific plate. [ABSTRACT FROM AUTHOR]

Porphyry copper and mixed copper-gold sulfide deposits contain varying amounts of precious (gold and silver) and platinum group metals (PGMs). Currently, milling and froth flotation is the most common processing route for the treatment of high-grade base metal sulfide ores. During this process, the precious metals and PGMs are also concentrated and represent a possible opportunity for the beneficiation of these metals to increase the overall economic value of the ore. Although not yet commercialized, the high temperature pressure oxidation (POX) of copper concentrates provides an alternative processing route to traditional smelting technology. With increasingly aggressive air quality standards and rising upstream processing costs for smelting, hydrometallurgical processing options become progressively attractive. The treatment of POX residues for the recovery of precious metals has seen significant attention and multiple processing routes have been developed on various scales. Extraction and beneficiation of PGMs from copper concentrate POX residue has garnered significantly less attention and mechanistic questions remain to be answered. Based on a review of the processing options for PGM ores and concentrates, hydrometallurgical processing routes for the extraction of PGMs from copper concentrate POX residues are envisioned. [ABSTRACT FROM PUBLISHER]

The Almalyk porphyry cluster in the western part of the Central Asian Orogenic Belt is the second largest porphyry region in Asia and hence has attracted considerable attention of the geologists. In this contribution, we report the zircon U–Pb ages, major and trace element geochemistry as well as Sr–Nd isotopic data for the ore-related porphyries of the Sarycheku and Kalmakyr deposits. The zircon U–Pb ages (Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)) of ore-bearing quartz monzonite and granodiorite porphyries from the Kalmakyr deposit are 326.1 ± 3.4 and 315.2 ± 2.8 Ma, and those for the ore-bearing granodiorite porphyries and monzonite dike from the Sarycheku deposit are 337.8 ± 3.1 and 313.2 ± 2.5 Ma, respectively. Together with the previous ages, they confine multi-phase intrusions from 337 to 306 Ma for the Almalyk ore cluster. Geochemically, all samples belong to shoshonitic series and are enriched in large-ion lithophile elements relative to high field strength elements with very low Nb/U weight ratios (0.83–2.56). They show initial (87Sr/86Sr)iratios of 0.7059–0.7068 for Kalmakyr and 0.7067–0.7072 for Sarycheku and low εNd(t) values of −1.0 to −0.1 for Kalmakyr and −2.3 to 0.2 for Sarycheku, suggesting that the magmas were dominantly derived from a metasomatized mantle wedge modified by slab-derived fluids with the contribution of the continental crust by assimilation-fractional-crystallization process. Compared to the typical porphyry Cu deposits, the ore-bearing porphyries in the Almalyk cluster are shoshonitic instead of the calc-alkaline. Moreover, although the magmatic events were genetically related to a continental arc environment, the ore-bearing porphyries at Sarycheku and Kalmakyr do not show geochemical signatures of typical adakites as reflected in some giant porphyry deposits in the Circum-Pacific Ocean, indicating that slab-melting may not have been involved in their petrogenesis. [ABSTRACT FROM AUTHOR]

We have studied the correlation between bulk mineralogy and induced polarisation (IP) responses in iron oxide-copper-gold (IOCG) and porphyry copper mineralised systems in northern Chile. Twelve drillholes (> 5000 m) that intersect IP sections were mapped and sampled to obtain geological characteristics and to quantify metallic minerals concentration in ore bodies. Geological parameters and modelled geophysical responses (electrical chargeability and resistivity) were compared using qualitative and quantitative criteria. Data analyses show that bulk sulphide concentration is the major factor that explains variations in the IP effect, even for IOCG ore bodies associated with magnetite mineralisation (up to 5 vol. %). Electrical chargeability exhibits a direct, but non-linear proportionality with sulphides content, while no clear trend is observed when chargeability is compared to magnetite concentration. In drillhole segments where macroscopic sulphides were not mapped, but IP results suggested high chargeabilities, petrographic studies revealed at least 1 vol. % of pyrite occurring as micro crystals (< 0.125 mm). The apparent resistivity data do not show any direct relationship with chargeability or sulphide contents. [ABSTRACT FROM AUTHOR]

The Neo-Tethyan subduction in Iran is characterized by the Urumieh–Dokhtar magmatic arc (UDMA), formed by northeast-ward subduction of the oceanic crust beneath the central Iran. This belt coincides with the porphyry copper metallogenic belt that comprises several metallogenic zones, including Ahar–Jolfa in northwest Iran. The Ahar–Jolfa metallogenic zone encompasses two main batholiths of Qaradagh and Sheyvardagh and numerous intrusive bodies of Cenozoic, which have produced many base and precious metal deposits and prospects. The former is considered as continuation of the Meghri–Ordubad pluton in South Armenian Block (SAB), which also hosts porphyry copper deposits (PCDs). The Sungun PCD is the largest occurrence in northwest Iran. Rhenium-Osmium ages of Sungun molybdenites are early Miocene and range between 22.9 ± 0.2 and 21.7 ± 0.2 Ma. Comparison of the ages obtained here with published ages for mineralization across the region suggests the following sequence. The earliest porphyry Cu–Mo mineralization event in northwest Iran is represented by Saheb Divan PCD of late Eocene age, which is followed by the second epoch of middle Oligocene, including the Cu–Mo–Au mineralization at Qarachilar and the Haftcheshmeh PCD. Mineralization in Sungun, Masjed Daghi, Kighal and Niaz deposits corresponds to the third mineralization event in northwest Iran. The first epoch in northwest Iran postdates all Eocene mineralizations in SAB, while the second epoch is coeval with Paragachay and the first-stage of Kadjaran PCDs. Its third epoch is younger than all mineralizations in SAB, except the second stage in Kadjaran PCD. Finally, the Cu mineralization epochs in northwest Iran are older than nearly all PCDs and prospects in Central Iran (except the Bondar Hanza PCD), altogether revealing an old to young trend along the UDMA and the porphyry Cu belt towards southeast, resulted from diachronous, later closure of the Neo-Tethyan oceanic basin in central and SE Iran. [ABSTRACT FROM PUBLISHER]

The NS-treading Zhongdian Arc located in the southern part of the Yidun Arc is an important region to address the evolution and reconstruction of the Palaeo-Tethys Ocean and related mineralization. In this study, we investigate three barren intrusions in the Zhongdian Arc and present geochemical compositions, zircon U–Pb dating and Hf isotopic compositions. Zircons from the three intrusions yielded U–Pb ages of ~227.5, ~222.5, and ~230 Ma, with highly variableεHf(t) values (‒20.5 to 4.3). These quartz monzonite porphyries show typical adakitic affinity, and it is inferred that these intrusions in the Zhongdian Arc, together with those in the northern Yidun Arc, were derived from the partial melting of mantle wedge and contaminated by minor lower crustal components during the westward subduction of the Ganzi-litang Ocean, which probably resulted from the Triassic continental collision between the south China and the north China blocks. In the Yidun Arc, the Triassic ore-bearing intrusions haveεHf(t) values that cluster around zero, while the barren intrusions possess negativeεHf(t) values, suggesting that the mantle lithospheric components played an important role in the Triassic ore-bearing porphyries. [ABSTRACT FROM AUTHOR]

A major metallogenic belt with substantial resources of gold, lead, zinc, copper, and molybdenum is present in the southern Zhangguangcai Range, NE China. Several large porphyry Mo deposits are located in this belt, as for example at Jidetun, Fu’anpu, and Daheishan. Five molybdenite samples from the Jidetun deposit yielded an Re–Os isochron age of 168.6 ± 2.1 Ma (mean standard weighted deviation = 0.20), and this is consistent with the Re–Os isochron ages of the other Mo deposits in the southern Zhangguangcai Range, giving a Middle Jurassic age for metallogenesis. The Jidetun, Fu’anpu, and Daheishan deposits all tend to have weakly enriched34S values of 0.80‰–3.20‰ and relatively low Re contents ranging from 3.073 to 43.567 ppm, which indicates the ore-forming materials were derived mainly from granitic magmas that had an origin in the mixture of crust and mantle. Three stages of mineralization can be identified in the deposits at Jidetun, Fu’anpu, and Daheishan. The original ore-forming fluids in stage I were characterized by high-temperature magmatic hydrothermal fluids that were most likely derived by exsolution from the Middle Jurassic ore-bearing magmas. However, two different fluid systems, NaCl–H2O–CO2fluids and NaCl–H2O fluids, were widespread in stage I of porphyry Mo deposits in the southern Zhangguangcai Range. Taking into account the regional geological characteristics and tectonic setting, we suggest that two different emplacement modes of the ore-bearing magmas explain the different fluid systems in stage I: the first magmas were emplaced along the contact zones between the strata and earlier granitoids, whereas the second magmas were emplaced entirely within the earlier granitoid intrusions. The stage II and III fluids were characterized by relatively lower temperatures and low H–O isotopic values, indicating a gradual evolution from magmatic to meteoric sources. [ABSTRACT FROM AUTHOR]