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Ultra-high-pressure (UHP) metamorphic rocks in the Western Gneiss Region (WGR) of Norway formed in subducted Baltican crust during the Scandian phase of the Caledonian orogeny. In the Nordøyane UHP domain, eclogites locally preserve coesite and microdiamond. Along the north coasts of Haramsøya and Flemsøya, in situ eclogite bodies are surrounded by dioritic "diatexite selvages" containing abundant eclogitic enclaves and xenocrysts. In one location eclogite and diatexite are associated with a quartz diorite dyke that is highly contaminated with eclogitic material. The diatexite matrix and dyke have similar plagioclase + quartz + biotite assemblages with abundant embayed and fragmented garnet and clinopyroxene xenocrysts. Coesite is present in some garnet xenocrysts but has not been found in the adjacent eclogite bodies. Pressure–temperature (P–T) estimates from in situ eclogites range from 2.2–3.2 GPa and 810–840 °C, spanning the quartz–coesite transition, with P–T estimates from xenocrysts spanning a wider range. Diorites and retrogressed eclogites record amphibolite-facies conditions, ca. 1.0–1.5 GPa and 700–800 °C. The wide range and large uncertainties in P–T estimates reflect high-temperature re-equilibration and a relative lack of P-sensitive assemblages. Differences in texture, composition, and included assemblages indicate that the xenocrysts were not derived from the nearby eclogite bodies. By implication, their dioritic hosts were not locally derived but must have originated from a different, probably deeper, source. The results are integrated with a numerical model for WGR tectonic evolution to assess the sources of the melts and their possible effects on the exhumation of UHP rocks in western Norway. [ABSTRACT FROM AUTHOR]

For the purpose of this study, four natural rock samples-namely, diorite, granodiorite, tonalite, and granite-are being investigated about their radiation attenuation. The elemental composition of the rocks was obtained through Energy dispersive X-ray spectroscopy (EDX) which examines the microstructural and localized area elemental analyses of the four rock samples. A Monte Carlo simulation (MCNP) was used to determine and evaluate the investigated samples. Additionally, the samples were validated by Phy-X software (within the energy range of 0.015 to 15 MeV), and experimental measurements were achieved through the utilization of an HPGe detector (0.060, 0.662, 1.173, and 1.332 MeV). The investigation was carried out using various parameters such as linear attenuation (µ) and others. Furthermore, the Fast Neutrons Removal Cross Sections (FNRCS) were calculated using theoretical methods. In the case of granodiorite, tonalite, diorite, and granite, the values of µ were found to range from 7.931 to 0.049, 31.922 to 0.061, 17.267 to 0.060, and 23.860 to 0.056 cm−1, respectively. The samples of tonalite and diorite have the highest µ values due to the presence of heavy elements and the high densities of these samples. Granodiorite is the substance that possesses the highest value of FCS (0.108 cm−1) due to the high content of light elements (O = 0.6802%, and C = 0.2286% wt). The results of the study demonstrated that the investigated natural rocks possessed a substantial potential for shielding γ-rays and neutrons from radiation and could be suitable for use in radiological protection applications. [ABSTRACT FROM AUTHOR]

The formation of early Mesozoic granitoid plutons in the Qinling Orogen is widely regarded as a result of the collision and accretion between the Yangtze Block and the South Qinling Block during the early Mesozoic, but the specific magmatic process, source composition, tectonic environment and deep dynamic background remain controversial. This study reports the petrology, zircon U–Pb geochronology, and whole-rock geochemistry of diorites from the Liuba and Qingyangyi plutons in the South Qinling, to provide new evidence for understanding the final collision tectonic evolution process of Qinling Orogenic belt. The Liuba and Qingyangyi plutons, located in the central part of the South Qinling region, are primarily composed of quartz diorite and quartz monzodiorite, respectively. The results indicate that the weighted mean crystallization ages of the quartz diorite in the Liuba pluton range from 216.1 ± 0.8 Ma to 217.1 ± 1.3 Ma, with the weighted mean crystallization ages of its MMEs being 215.4 ± 1.0 Ma. The crystallization ages of the quartz monzodiorite in the Qingyangyi pluton range from 214.6 ± 0.9 Ma to 215.4 ± 0.9 Ma, suggesting that both plutons were formed in the late Triassic. The investigated plutons are characterized as right-leaning and have weak negative Eu anomalies on the chondrite-normalized REE patterns diagram. The large ion lithophile elements (LILE) Rb, Ba, Th and K are relatively enriched, while high-field strength elements (HFSE) Nb, Ta, Ti and P are strongly depleted. The formation of numerous MMEs in the Liuba pluton is the product of magmatic mixing. The Liuba and Qingyangyi plutons are the results of crust thickening and partial melting of lower crust caused by the comprehensive late Triassic collision between the Yangtze Block and the North China Block (NCB), and are the manifestation of magmatic intrusion along the South Qinling tectonic belt in the late Triassic period. [ABSTRACT FROM AUTHOR]

The Western Cordillera of Colombia preserves the remnants of the Cretaceous tectonic history of the northernmost Andes, including fragments of Ecuadorian-Colombian-Leeward Antilles Arc formed during the northeastward movement of the Caribbean plate. Although the granitoid rocks (such as the Santa Fe tonalite) that constitute the arc crust have been extensively studied, the mafic-ultramafic rocks hosted within the felsic facies, along with their textural variations and potential genetic relationships, remain less understood. This study focuses on the Pantanillo Granulites, analysing their mineral composition to determine their pressure and temperature conditions of formation through pseudosections. Our findings indicate that the Pantanillo granulite-facies rocks formed under pressures ranging from 0.87 to 1.12 GPa and temperatures between 940°C and 1050°C, corresponding to crustal depths of 20–30 km and a high geothermal gradient. Field and petrographic observations suggest that the Santa Fe batholith and the Pantanillo granulites are consanguineous, forming part of an appinite suite characterized by the common presence of large hornblende crystals. [ABSTRACT FROM AUTHOR]

To understand the accretionary processes of the Central Asian Orogenic Belt, we must first identify the period from initial subduction to slab rollback and the mature mechanism of island arcs. The Boshchekul-Chingiz arc, one of the most important Marianatype island arcs in the southwestern Central Asian Orogenic Belt, is marked by systematic Paleozoic magmatism that occurred in response to specific evolutionary stages of the Paleo-Asian Ocean, but controversy about its tectonic evolution still exists. Thus, we conducted a detailed field investigation and geochronological, geochemical, and isotopic analyses on magmatic rocks across the Xiemisitai Mountains, the eastern extension of the Boshchekul-Chingiz arc in northern West Junggar, Northwest China. Magmatic activity in the Xiemisitai Mountains occurred mainly from the Middle Cambrian to the Early Devonian. Middle Cambrian quartz diorite (ca. 502 Ma) in the southern Xiemisitai Mountains is marked by initial arc magmas characterized by flat rare earth element patterns, enrichment in large ion lithophile elements, and depletion in high field strength elements. Its depleted mantle-like Sr-Nd-Hf isotopes suggest that it was directly extracted from depleted mantle. Late Ordovician-Early Devonian mafic-intermediate volcanic rocks (ca. 446-415 Ma) are most often exposed. These are mature arc magmas with high La/Yb, Th/Zr, and Th/Yb ratios. Their high La/Sm ratios, low Ce/Pb ratios, and depleted mantle-like Sr-Nd-Hf isotopes indicate that they were likely derived from depleted lithospheric mantle intensively metasomatized by slab-derived fluids. Widespread middle Silurian-Early Devonian felsic volcanic rocks (ca. 426-417 Ma) are geochemically equivalent to those of A2-type and I-type granitoids. The juvenile isotopic compositions and crust-like Zr/Hf ratios imply that they originated from juvenile crust remelting with the involvement of the asthenosphere. We suggest that the eastern Boshchekul-Chingiz arc was born by northward subduction (in today's direction) of the Junggar Ocean (a branch of the Paleo-Asian Ocean) since 502 Ma. Then it transformed from a nascent arc to a mature island arc with the advancing migration of magmatism during the Late Ordovician-middle Silurian. Rollback of the Junggar oceanic slab occurred during the middle Silurian-Early Devonian and led to coeval retreating migration of magmatism and transformation to an extensional setting. The newly established tectonic framework of the Boshchekul-Chingiz arc from this study, combined with the coeval accretionary tectonic model for other parts of the Central Asian Orogenic Belt, convincingly indicates that a large-scale intra-oceanic subduction system existed in the Central Asian Orogenic Belt since the Cambrian, and a tectonic transition from advancing to retreating orogenesis exclusively occurred in the Silurian-Early Devonian due to slab rollback. Thus, it would take 70-100 m.y. from initial subduction to incipient slab rollback for the Paleo-Asian Ocean, which is important for understanding the early stage of orogenic evolution for the Central Asian Orogenic Belt. This study provides overall evidence of the potential period from initial subduction to slab rollback of the Paleo-Asian Ocean, and may be of great importance for inferring the paleo-subduction and evolution of orogens elsewhere. [ABSTRACT FROM AUTHOR]

ABSTRACT The geodynamic background of late Mesozoic magmatism in eastern Inner Mongolia remains debated owing to multi‐plate influences. Here, we present zircon U–Pb geochronology, geochemistry and Hf isotope data for Late Jurassic diorite and Early Cretaceous quartz monzonite porphyry and granite porphyry to investigate the petrogenesis and tectonic setting. Zircon U–Pb data suggest that multiphase magmatism extended from the Late Jurassic to the Early Cretaceous, that is, 161.0 ± 1.0 Ma (diorite), 129.9 ± 1.4 Ma (quartz monzonite porphyry), 125.8 ± 1.1 Ma and 126.8 ± 1.1 Ma (granite porphyry). The dioritic samples have lower SiO2 (55.41–56.75 wt%), higher MgO (4.22–4.57 wt%) and Mg# (52–55). The quartz monzonite shows mediate SiO2 contents (63.17–64.89 wt%), belonging to the high‐K, calc‐alkaline series. The granite porphyry samples exhibit higher SiO2 (74.49–77.03 wt%) and Na2O + K2O (6.37–7.38 wt%) contents, while lower Mg# (20–25). The diorites and quartz monzonite porphyry show slight negative Eu anomalies (δEu = 0.85–0.88 and 0.78–0.90, respectively), while Eu anomalies are intensely for the granite porphyry (δEu = 0.45–0.67). All these rocks show enrichments in LILEs (U and Pb) and depletions in HFSEs (Nb, Ta, P and Ti). The clinopyroxenes are classified as augite and diopside, and they show slightly inverted U‐shaped patterns in the chondrite‐normalised REE diagram. The plagioclases are mainly andesine from the diorites, while they are albite from the quartz monzonite porphyry and granite porphyry. The εHf (t) values of zircon crystals range from +3.04 to +5.90, +2.04 to +4.10 and +1.93 to +4.35. These data indicate that the diorite formed by low degree partial melting of a depleted mantle wedge metasomatized by fluids. The quartz monzonite porphyry was generated by partial melting of the lower crust triggered by the underplating of depleted mantle‐derived basaltic magma. The granite porphyry is classified as S‐type granite and was sourced from greywacke. Combined with previous data, we conclude that Late Jurassic magmatism was related to the southward subduction of the Mongol‐Okhotsk Ocean, while the Early Cretaceous magmatic rocks formed in a post‐collision extensional setting. [ABSTRACT FROM AUTHOR]

Volcanogenic massive sulfide (VMS) deposits with advanced argillic alteration display characteristics typical of conventional VMS and high-sulfidation epithermal deposits. Unlike conventional VMS deposits, these "hybrid" VMS are interpreted to have formed through a magmatic fluid contribution to an evolved, seawater-dominated, hydrothermal system. The close spatial association of advanced argillic alteration assemblages with more typical chlorite–sericite assemblages in the same VMS deposit has implications for the controls on magmatic versus seawater convective systems that have not been previously addressed in the literature. The Neoarchean Onaman assemblage (ca. 2780–2769 Ma) in northwestern Ontario hosts a conventional base metal VMS system with chlorite–sericite alteration that is overprinted by argillic and advanced argillic alteration, now manifested as a metamorphosed zone of kyanite–chloritoid–calcite–Fe–chlorite, that is associated with a barren, pyritic VMS deposit. The change from typical to advanced argillic alteration occurred during, or immediately following, the deposition of a tonalite clast-bearing heterolithic breccia, which recorded the uplift and subaerial exposure of the larger volcanic edifice. We postulate that the reactivation of synvolcanic structures during uplift, concomitant localized subsidence, and magmatism enhanced cross-stratal permeability and allowed for a direct magmatic volatile input into, or overprint on, an evolved seawater-dominated hydrothermal system. Our results suggest that geodynamic regimes exert a strong local, and possibly regional, control on the style, timing, and fluid characteristics of VMS hydrothermal systems. The association of advanced argillic alteration with barren pyritic massive sulfide also suggests that magmatic volatile input alone is not sufficient to enrich VMS systems in gold. This interpretation is consistent with observations from other magmatic–hydrothermal systems such as porphyry and epithermal deposits. [ABSTRACT FROM AUTHOR]

ABSTRACT The influence, extent, intensity, and spatiotemporal evolution of the subduction of the Paleo‐Pacific Plate on West‐Central North China Craton during the middle‐late Mesozoic remains unknown. Detailed petrological investigations, systematic zircon U–Pb dating, whole‐rock geochemistry, and in situ zircon Lu‐Hf isotopic analysis were conducted on various lithologies of the composite pluton in the central part of the North China Craton. The composite pluton can be divided into four distinct periods: quartz‐porphyry (162 ± 1 Ma), porphyritic biotitic granite (152 ± 1 Ma), quartz diorite (142 ± 1 Ma), granite (136 ± 2 Ma). These rocks are belonged to high silica, potassium‐calcareous alkalinity, aluminium content and enriched in large‐ion lithophile elements such as Rb and K, and depleted in high‐field‐strength elements such as Nb and Ta. The εHf(t) values and the TDMC ages of the quartz‐porphyry, porphyritic biotitic granite indicated these igneous rocks originated from the lower crust to the mid‐lower crust which exhibit a lithospheric evolution process consistent with that of the North China Craton. The εHf(t) values of quartz diorite and granite indicate that the igneous rocks originated from the ancient lower crust with contributions of mantle‐derived material, and from a mixture of the ancient mid‐lower crust and the Late Palaeozoic younger lower crust. Considering the regional geological background, it is believed that this magmatism indicates a transition in the central North China Craton from compression to extension from the Late Jurassic to the Early Cretaceous. This transition is associated with the subduction of the Paleo‐Pacific Plate, which began subducting under eastern Asia in the Early Jurassic and led to an extensional state in the Cretaceous due to the retreat of the Pacific subduction slab. [ABSTRACT FROM AUTHOR]

The Zaozigou gold deposit lies south of the Xiahe–Hezuo regional fault zone in the western Qinling orogenic belt and contains many intermediate to felsic dikes. Diorite porphyry, quartz diorite porphyry and biotite diorite porphyry are mineral‐bearing dikes, whereas granite porphyry is unrelated to gold mineralization. To compare the relationship between different dikes and mineralization, this study analyzed the cathodoluminescence (CL) of zircon crystals in all four types of dikes exposed in the Zaozigou deposit, using a zircon typological classification. The formation temperature of the granite porphyry (734°C) was higher than the average temperature of the other three types of dikes (704°C), whereas the former's alkalinity index (395) was lower than the average alkalinity index of the other three dikes (425). The ΣREE amount of granite porphyry (147.18 ppm) was smaller than the average ΣREE amount of the other three dikes (246.80 ppm) and its δEu value (0.33) was larger than the average δEu values of the other three dikes (0.30). The U‐Pb ages of zircon in the four types of dikes were relatively consistent with the crystallization ages of approximately 240 Ma, which indicates that all four types of dikes intruded in the Middle Triassic. Compared to the other three ore‐bearing dikes, the morphology of the zircon crystals in the barren dikes evolved from S13 to S5 and then returned to S13. These results indicate that the barren dike underwent an increase in temperature and a decrease in alkalinity, which may be an important reason for the absence of mineralization. [ABSTRACT FROM AUTHOR]

The Huxu Au-dominated polymetallic deposit is a hydrothermal deposit located in the Dongxiang volcanic basin in the middle section of the Gan-Hang tectonic belt in South China. The orebodies primarily occur within the Jurassic-Cretaceous quartz diorite porphyry, while the genesis of this deposit is unclear. This study focused on geological and mineralogical characteristics, in-situ trace elements and S-Pb isotopes of three generations of pyrite of the Huxu deposit to clarify the distribution of trace elements in pyrite, ore-forming fluid and material sources, and genetic types of the deposit. The mineralization stage of the deposit can be divided into quartz-pyrite stage (S1), quartz-pyrite-hematite stage (S2), quartz-polymetallic sulfide stage (S3) and quartz-hematite stage (S4), with the corresponding pyrite being divided into three generations (Py1–Py3). in-situ trace element data of pyrite show that Au in pyrite mainly exists in the form of solid solution (Au+), and the content is relatively low at all stages (0.18 ppm for Py1, 0.32 ppm for Py2, 0.68 ppm for Py3), while Pb and Zn mainly exist as sulfide inclusions in the pyrite. S-Pb isotopes show that the sulfur and ore-forming material of this deposit are mainly sourced from magma. The mineral association, mineral textures and trace elements in different stages of pyrite indicate that fluid boiling and fluid mixing are the key factors of native gold precipitation in S2 and S4, respectively, while water-rock interaction controlled the precipitation of Pb-Zn sulfides. These integrating with geological characteristics suggests that the deposit should be an intermediate sulfidation epithermal deposit. [ABSTRACT FROM AUTHOR]

The Sanyanlong-Galazi granite complex is located in the southern part of the Songpan-Garze orogenic belt, a region with unique structural characteristics. Detailed studies of its chronology and isotopic features are crucial for understanding the complex tectonic evolution and basement properties of the orogenic belt. Through detailed field investigations and microscopic observations, using LA-ICP-MS zircon U–Pb dating and Lu–Hf isotopic analysis, we found that this complex granite body was emplaced in the Triassic Xikang Group strata. It exhibits a rock evolution sequence of quartz diorite, granodiorite, and monzogranite. The formation ages of monzogranite and granodiorite are 211.5 ± 1.2 and 215.6 ± 1.1 Ma, respectively. Zircon Hf isotopic 176Hf/177Hf values range from 0.282347 to 0.282640, with εHf(t) values ranging from –10.38 to –0.50, and two-stage Hf model ages from 1173 to 1896 Ma. Comprehensive analysis suggests that the Sanyanlong-Galazi pluton formed in the late Indosinian period within a post-collisional tectonic setting. This indicates that the Garze-Litang ocean had closed by the Late Triassic (215 Ma). The material source is newly formed crust from the early to middle Proterozoic, confirming the possible existence of a Precambrian basement similar to the Yangtze Block in the southern margin of the Songpan-Garze orogenic belt. [ABSTRACT FROM AUTHOR]

The Las Cruces intrusive suite is located at the southern extent of the Baja California Peninsula in northwestern Mexico. The suite constitutes the northern part of the Los Cabos Batholitic Complex. It is correlated with extensive Cretaceous magmatic activity extending across California and the Baja Peninsula, known as the Peninsular Ranges Batholith. Despite its significance for understanding the regional tectonic and magmatic evolution, detailed information to fully support this correlation remains limited. This work provides new cartographic and structural data of the units comprising the intrusive suite and the temporal relationships between lithological units, supported by U-Pb zircon geochronology. The suite consists of granite in its central part, tonalite displaying magmatic foliation at its NW and SE margins, and two gabbro apophyses along the western edge. The host rocks consist of intercalations of hornblende and biotite schists, forming screens and roof pendants. Late magmatic felsic dikes, derived from the granite, intrude into the suite units. Five new U-Pb zircon age determinations indicate that the suite has a normal crystallization history with ages from 103.5 ± 1.2 to 97.6 ± 0.8 Ma for the tonalite and from 93.6 ± 0.7 to 95.0 ± 0.9 Ma for the granite. The gabbro is the oldest intrusive unit, with previous U-Pb zircon ages reported near 109 ± 2.3 and 102.3 ± 2.9 Ma. Structural analysis indicates that the gabbro and tonalite were emplaced during an E–W synmagmatic compressional event, evidenced by N–S oriented magmatic foliation, aligning subparallel to the granite and metasedimentary screens contacts. Later, the granite was emplaced during a compressional stress relaxation phase, causing the tonalite dissection and forming the current suite margins. The calculated U-Pb ages for the Las Cruces intrusive suite and reported geochemical and geophysical data from the northern Baja California Peninsula support its correlation with the Peninsular Ranges batholith. [ABSTRACT FROM AUTHOR]

We conducted a study on the petrology, geochemistry, and zircon U–Pb dating of Late Devonian intrusive rocks in the Tulargen area of the Eastern Tianshan Orogenic Belt, Xinjiang, China. These intrusive rocks primarily consist of gabbro (382 ± 5 Ma), tonalite (370.9 ± 2.7 Ma), and biotite monzogranite (362.8 ± 4.4 Ma). Gabbro belongs to the low-K calc-alkaline series of quasi-aluminous rocks, with a high Al2O3 content (16.46–20.34 wt.%) and Mg# value (64.55–67.73). Tonalite and biotite monzogranite, which belong to the high-K calc-alkaline series, are metaluminous or weakly peraluminous and also exhibit high Al2O3 contents (14.6–15.87 wt.%) and Mg# values (40.12–62.47). These rocks are enriched in light rare-earth and large-ion lithophile elements (Rb, Ba, and K) and depleted in heavy rare-earth and high-field-strength elements (e.g., Ta, Nb, and Ti), characteristics typical of island-arc magmatic rocks. Gabbro melts are primarily derived from the mantle and result from the partial melting of a depleted mantle that has undergone fluid metasomatism due to subducted plates. Tonalite exhibits high 176Hf/177Hf and εHf(t) values, with a younger two-stage model age (tDM2) derived from partial juvenile crust melting. The source magma of the biotite monzogranite originated from partial metabasalt melting at a medium crustal depth combined with a new lower crustal material. We concluded that the Late Devonian intrusive rocks in this area formed within the island-arc tectonic setting are associated with the subduction of the North Tianshan Ocean. [ABSTRACT FROM AUTHOR]

The Deki Amhare complex is located in central Eritrea, within the Arabian–Nubian Shield (ANS). It consists of an inner core of monzogranite porphyry and diorite enclaves (MMEs), surrounded outwardly by granodiorite and quartz diorite. The zircon U–Pb ages, whole-rock geochemistry, and Sr–Nd–Hf isotopic compositions of the Deki Amhare complex granitoids were used to discuss the Neoproterozoic tectonics of the ANS. The Late Tonian granodiorite and quartz diorite are metaluminous and calc-alkaline to slightly high-K calc-alkaline I-type plutons, with ages of 811.2 ± 4.8 Ma and 811.6 ± 5.7 Ma, respectively. They exhibit positive εHf(t) (7.6–9.5) and εNd(t) (3.9–4.7) values and relatively low (87Sr/86Sr)i ratios (0.70374–0.70463), indicating that they derived from the partial melting of a metasomatized mantle wedge during intra-oceanic subduction. The Ediacaran monzogranite porphyry and MMEs are subalkaline to alkaline A2-type granitoids with ages of 620.0 ± 4.3 Ma and 614.8 ± 3.9 Ma. These display positive εHf(t) (5.3–8.7) and εNd(t) (4.2–4.7) values, as well as low (87Sr/86Sr)i ratios (0.70310–0.70480), implying that they formed through crust–mantle magma mixing related to post-collisional slab break-off. Based on these data, three stages of regional tectonic evolution can be described: (1) from ~1200 Ma to ~875 Ma, the mafic oceanic crust was derived from depleted mantle during the opening of the Mozambique Ocean; (2) from ~875 Ma to ~630 Ma, intra-oceanic subduction and arc formation occurred with the development of I-type batholiths; and (3) from ~630 Ma to ~600 Ma, crustal and lithospheric reworking took place post-collision, leading to the formation of A2-type granitoids. [ABSTRACT FROM AUTHOR]

The migration and character of magmatism over time can provide important insights into the tectonic evolution of an orogen. We present evidence for three separate stages of compositionally distinct granitoid magmatism associated with the Acadian orogenic cycle in the eastern and southern Newfoundland Appalachians. The interpretations are based on new zircon U-Pb ages, geochemical data, and Sr-Nd-Hf-O isotopic data for 18 samples from 15 Silurian and Devonian granitoid plutons, combined with previously published data. The three stages outline hinterland- and foreland-directed migration trends and represent subduction (435-420 Ma), syncollision (415-405 Ma), and postcollision (395-370 Ma) settings in the Acadian orogenic cycle. The Silurian plutons (435-420 Ma) of the first stage consist mainly of quartz diorite, tonalite, granodiorite, monzogranite, and syenogranite, with high-K calc-alkaline and enriched Sr-Nd-Hf-O isotopic compositions (e.g., eNd[t] = -5 to -2; eHf[t] = -3 to -1; d18O = +6? to +8?). They are interpreted to record the subduction of oceanic lithosphere of the Acadian seaway that separated the leading edge of composite Laurentia, represented by the Gander margin, and Avalonia. Early Devonian plutons (415-405 Ma) of the second stage contain more voluminous monzogranite and syenogranite; they have calc-alkaline to high-K calc-alkaline features, adakite-like compositions, and more depleted Sr-Nd-Hf-O isotopic compositions (e.g., eNd[t] = -6 to 0; eHf[t] = +1 to +3; d18O = +5? to +6?). Plutons of this stage occur mostly to the northwest of the Silurian granitoids, indicating a regional-scale northwestward (hinterland-directed) migration of magmatism with a rate of >9 km/m.y. The migration is interpreted to have been related to the progressive shallow underthrusting of Avalonia beneath the Gander margin (composite Laurentia) at least as far as 90 km inboard. The Middle to Late Devonian plutons of the third stage (395-370 Ma) consist mainly of monzogranite, syenogranite, and alkali-feldspar granite, which are silica- and alkali-rich granites with large negative Eu anomalies. These rocks are concentrated along both sides of the Dover-Hermitage Bay fault zone, which represents the boundary between Avalonia and composite Laurentia, to the southeast of the Silurian and Early Devonian igneous rocks. This stage of magmatism represents a foreland-directed (retreating) migration. The Early Devonian and Middle to Late Devonian episodes of magmatism were separated by a gap between 405 Ma and 395 Ma and recorded an evolution from (high-K) calc-alkaline to alkaline compositions, ascribed to partial delamination of Avalonian lithospheric mantle in a postcollisional setting. [ABSTRACT FROM AUTHOR]

Crustal growth is closely associated with the oceanic subduction process, although the precise mechanism involved remains poorly constrained. Northeast (NE) China is an important component of the largest accretive orogenic belt worldwide – Central Asian orogenic belt. Its accretionary process was dominated by the Paleo-Asian and Paleo-Pacific Oceans; thus, NE China can provide a promising insight to explore this complex mechanism. We report new geochronological, geochemical and Hf isotopic compositions of the igneous rocks found in the Central Jilin Province, NE China. The geochronological results reveal that these igneous rocks were formed during 174.7 − 167.7 Ma (i.e. Early−Middle Jurassic). The quartz diorite and monzogranites from the northeastern margin of the North China Craton have high Sr (314 − 757 ppm) content, (La/Yb)N (7.11 − 29.9) and Sr/Y (41.50 − 157) ratios, low Y (2.03 − 12.97 ppm) and Yb (0.30 − 1.34 ppm) contents, exhibiting adakitic features. Coupling with their significant negative εHf(t) values (−32.51 to − 5.45), we propose that these igneous rocks were originated from the partial melting of an ancient thickened lower crust. In contrary, the syenogranite, granite porphyry, and porphyritic monzogranite from the Zhangguangcai and Jiamusi blocks are characterized by high K calc-alkaline, low MgO (0.03 − 0.88 wt.%), Zr + Nb + Ce + Y (141 − 462 ppm) contents and Sr/Y (0.93 − 17.40) ratios, indicating an affinity of I−type granite. In view of their positive εHf(t) values (5.41 to 9.47), we suggest that they were originated from the partial melting of a juvenile lower mafic crust. Despite they have different magma sources, all the Jurassic igneous rocks exhibit typical geochemical signatures associated with subduction, such as enriched in large ion lithophile elements and depleted in high field strength elements. Considering the spatial-temporal distribution of coeval igneous rocks within the region, we propose that the Early Jurassic is the early subduction of the Paleo-Pacific Ocean. The Jurassic igneous rocks can be divided into two categories, one with high Sr/Y ratios and negative Hf isotope, and the others with low Sr/Y ratios and positive Hf isotope, which may indicate that crustal architecture in subduction zone has a significant effect on continental crustal growth and reworking in NE China. [ABSTRACT FROM AUTHOR]

The Abu Farayed Granite (AFG), located in the southeastern desert of Egypt, was intruded during the early to late stages of Pan-African orogeny that prevailed within the Arabian–Nubian Shield. The AFG intrudes an association of gneisses, island arc volcano–sedimentary rocks, and serpentinite masses. Field observations, supported by remote sensing and geochemical data, reveal a composite granitic intrusion that is differentiated into two magmatic phases. The early granitic phase comprises weakly deformed subduction-related calc–alkaline rocks ranging from diorite to tonalite, while the later encloses undeformed granodiorite and granite. Landsat-8 (OLI) remote sensing data have shown to be highly effective in discriminating among the different varieties of granites present in the area. Furthermore, the data have provided important insights into the structural characteristics of the AFG region. Specifically, the data indicate the presence of major tectonic trends with ENE–WSW and NW–SE directions transecting the AFG area. Geochemically, the AFG generally has a calc–alkaline metaluminous affinity with relatively high values of Cs, Rb, K, Sr, Nd, and Hf but low contents of Nb, Ta, P, and Y. The early magmatic phase has lower alkalis and REEs, while the later phases have higher alkalis and REEs with distinctly negative Eu anomalies. The AFG is structurally controlled, forming a N–S arch, which may be due to the influence of the wadi Hodein major shear zone. The diorite and tonalite are believed to have been originally derived from subduction-related magmatism during regional compression. This began with the dehydration of the descending oceanic crust with differential melting of the metasomatized mantle wedge. Magma ascent was long enough to react with the thickened crust and therefore suffered fractional crystallization and assimilation (AFC) to produce the calc–alkaline diorite–tonalite association. The granodiorite and granites were produced due to partial melting, assimilation, and fractionation of lower crustal rocks (mainly diorite–tonalite of the early stage) after subduction and arc volcanism during a late orogenic relaxation–rebound event associated with uplift transitioning to extension. [ABSTRACT FROM AUTHOR]

The Tau Blueschist in the headwaters of the Sepik River in north-central New Guinea occurs in an allochthonous east–west lens (55 × 8 km) known as the Tau body. The well-foliated Tau mafic schists contain abundant blue amphibole with some intimately associated pelitic–calcareous–graphitic metasediments. Within the Tau body, the metamorphic grade increases towards the north, from lawsonite rocks to epidote blueschists. Pumpellyitic lawsonitic metabasites are known only from river float. Isolated occurrences of coarsely crystalline mafic tectonic blocks (knockers) occur within and just north of the Tau body and comprise a complete spectrum from epidote blueschist to eclogite that includes amphibolite. The blueschists occur within the upper Mesozoic to Eocene Salumei Formation of prehnite–pumpellyite to low-greenschist facies grade. The Salumei Formation comprises a tectonic mixture of Upper Cretaceous mostly pelitic sediments derived from the Australian continent to the south and Eocene ophiolite fragments and arc-related volcanogenic rocks from the north. The region is dominated by west-to-northwest-trending folds, observed in most outcrops, and high-angle faults. The mesoscopic structures and steep dips of bedding and foliation in pre-Oligocene rocks suggest regional-scale isoclinal folding. Regionally, the Frieda and Fiak-Leonard Schultze faults separate the Salumei Formation (and Tau body) to the south from amphibolite and greenschist grade Ambunti Metamorphic rocks to the north; both may have the same protolith. The Ambunti Metamorphics, the Oligocene diorites intruding them and the Tau blueschists all rapidly cooled from ∼500 °C in the late Oligocene (ca 27–23 Ma). The Ambunti Metamorphics and Oligocene diorites are unconformably overlain by unmetamorphosed middle Miocene Wogamush Formation. Subsequent quartz diorite intrusions into the southernmost Ambunti and Salumei Formation metamorphics and the lower Wogamush Formation volcanics was part of the middle Miocene (ca 15 Ma) Maramuni Arc. We propose that the Sepik Terrane was separated from New Guinea in the Late Jurassic by a narrow backarc basin that was starved of sediment until the Late Cretaceous when the Salumei delta prograded across it. Paleogene subduction dipping northwards beneath the Sepik Terrane led to late Eocene to early Oligocene suturing to the New Guinea margin and partial exhumation of an accretionary wedge including the Tau Blueschist and serpentinised mantle slivers. Late Oligocene extension and diorite intrusion were associated with rapid cooling and exhumation of the metamorphic rocks. Subduction flipped and the middle Miocene Maramuni Arc and Wogamush Formation were emplaced followed by collisional tectonism with the Melanesian Arc. This placed the margin into compression and created the modern orogen. [ABSTRACT FROM AUTHOR]

The Punta del Cobre district near Copiapó is a center of iron oxide-copper–gold (IOCG) mineralization spatially and temporally associated with regional sodic-calcic hydrothermal alteration, the Atacama fault system (AFS), and two phases of Early Cretaceous magmatism. Here, we investigate the spatiotemporal and geochemical relationships between magmatism, ductile deformation, and hydrothermal alteration along the ~ 200 to 300-m-thick steeply NW-dipping Sierra Chicharra shear zone, interpreted to be the major strand of the AFS. Mylonitic fabrics and oblique sinistral-reverse kinematic indicators together record coaxial flattening in a transpressional regime. Deformation on the AFS took place before, during, and after intrusion of the synkinematic Sierra Chicharra quartz diorite of the Coastal Cordillera arc at ~ 122 Ma and terminated before intrusion of the unstrained ~ 114 Ma Sierra Atacama diorite of the Copiapó batholith. Geochemical data show that the Copiapó batholith was more mafic and more K-rich than the calc-alkaline Coastal Cordillera arc. This time period thus overlaps IOCG mineralization in the Punta del Cobre district (~ 120 to 110 Ma). Multiple phases of sodic-calcic alteration in and around the AFS shear zone are recognized. Textures of altered rock in the shear zone show both synkinematic assemblages and post-kinematic hydrothermal oligoclase. A ~ 775-m-long andradite vein that cuts the shear zone formed broadly at the end of magmatism in the district (~ 95 Ma). Oxygen isotope ratios from the vein indicate that hydrothermal fluids were likely magmatically derived. Together, this work shows the AFS-related shear zone and nearby IOCG mineralization developed in a regional transpressional regime produced by SE-directed oblique convergence across a NE-striking shear zone. IOCG-related magmatic-hydrothermal fluids exploited this transcrustal shear zone to produce multiple episodes of regional sodic-calcic alteration formed from fluids exsolved from magmas or driven by the heat of the Coastal Cordillera arc and Copiapó batholith. [ABSTRACT FROM AUTHOR]

The Great Xing'an Range (GXR) is a significant belt of polymetallic deposits located in the eastern segment of the Central Asian Orogenic Belt. The recently found Huoluotai porphyry Cu (Mo) deposit is situated in the northern GXR region in northeastern (NE) China. The deposit has been studied extensively using field geology and geochronological methods, which have identified two distinct mineralization events. These events include an early occurrence of porphyry-type Cu (Mo) mineralization and a later occurrence of vein-type Cu mineralization. Prior geochronology investigations have determined an approximate age of 147 Ma for the early porphyry-type Cu (Mo) mineralization. 40Ar/39Ar dating of K-feldspar of the altered Cu-mineralized quartz diorite porphyry veins for the overprinting vein-type Cu mineralization provides plateau ages of 123.1 ± 1.5 Ma, 122.3 ± 2.8 Ma, and 122.2 ± 0.4 Ma. Sulfide S-Pb isotope compositions of the two mineralization events suggest that both have a magmatic source. The origin of ore-forming metals displays the features of a crust–mantle mixing origin. The regional extensional tectonic setting in NE China during the Early Cretaceous was caused by large-scale lithosphere delamination and upwelling of the asthenospheric mantle. These processes were triggered by the rollback of the Paleo-Pacific Plate. The tectonic event in question resulted in the lithospheric thinning, significant magmatic activity, and mineralization in NE China. [ABSTRACT FROM AUTHOR]

Tongling Ore Concentration Area in Anhui Province is an important metallogenic area in the Middle-lower Yangtze Reaches Metallogenic Belt. The Dilongchong Gold Deposit is located in the middle of the ore concentration area, with the tectonic position on the northern margin of the Yangtze Plate. In recent years, typical deposits such as Yeshan Iron Deposit, Caojiachong Copper Deposit, Shujiadian Copper Deposit, and Yangchongli Gold Deposit have been discovered in this area. Through this field exploration work, combined with the existing achievements of the predecessors, the geological characteristics, metallogenic elements, and prospecting indicators of the Dilongchong Gold Deposit are systematically summarized, which provides a basis for further prospecting and exploration work. The results show that the metallogenic types of Dilongchong Gold Deposit are mainly fissure filling types and altered rock types. The genesis of the ore body (vein) is considered to be the late hydrothermal infusion, filling, or metasomatism mineralization. The ore bodies (veins) in the area are strictly controlled by the structure, and the NE-trending main structure and the NW-trending secondary structure are both ore-hosting structures. The intersection of the Fentou Formation, quartz diorite porphyry, and fault structure contact zone and its vicinity are key positions for finding gold deposits. The 4 mineralization alteration combinations of silicification specularite mineralization pyritization (limonite mineralization), specularite mineralization gold mineralization, silicitization pyritization, and beresitization are important prospecting indicators in the mining area and surrounding areas. [ABSTRACT FROM AUTHOR]

In recent years, the volcanic–plutonic relationship has been a contentious topic among researchers. Based on this issue, they have delved deeper into the constraints of magma reservoir pressure and H2O on pre-eruptive melt accumulation and migration. We selected granodiorite, tonalite, and rhyolite in the Dehailonggang volcanic–plutonic complex to investigate the volcanic–plutonic connection and constraints of reservoir pressure and H2O on the pre-eruptive melt accumulation and migration in water-rich systems. Granodiorite, tonalite, and rhyolite exhibit temporal–spatial similarities (247 Ma) and the same magmatic origin consisting of ca. 75–80% enriched mantle materials mixed with ca. 20–25% lower crustal materials. TESCAN integrated mineral analyzer (TIMA) shows that both granodiorite and tonalite display a typical cumulate texture. The bulk–rock compositional complementary of the granodiorite, tonalite, and rhyolite, coupled with in situ geochemical signatures of feldspars and zircons, feldspar CSD, and rhyolite–MELTS modeling, indicate that (1) the granodiorite represents the crystal cumulate formed after crystal–melt phase separation of the original mush (OM) in the magma reservoir; (2) the interstitial melt of the OM was extracted, migrated, and ultimately erupted as the rhyolite; (3) the tonalite serves as an intermediate product resulting from the phase separation from the OM to the rhyolite. Rhyolite–MELTS modeling reveals that in water-rich environments, an increase in reservoir pressure (prior to reaching overpressure threshold) can lead to a reduction in melt viscosity. This, in turn, accelerates mechanical compaction and phase separation processes, ultimately shortening the pre-eruptive melt aggregation timescale. In contrast, it is noteworthy that H2O has a relatively minor influence on phase separation in such water-rich systems (> 4 wt. %). This study demonstrates the volcanic–plutonic genetic coupling and highlights the significance of reservoir pressure in controlling the dynamics of pre-eruptive melt within water-rich systems. [ABSTRACT FROM AUTHOR]

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Magmatic periodicity is recognized in continental arcs worldwide, but the mechanism responsible for punctuated arc magmatism is controversial. Continental arcs in the Trans‐Himalayan orogenic system display episodic magmatism and the most voluminous flare‐up in this system was in early Eocene during the transition from subduction to collision. The close association of the flare‐up with collision is intriguing. Our study employs zircon Lu‐Hf and bulk rock Sr‐Nd isotopes, along with mineral geochemistry, to track the melt sources of the Nymo intrusive complex and the role of mantle magma during the early Eocene flare‐up of the Gangdese arc, Tibet. The Nymo intrusive complex is composed of gabbronorite, diorite, quartz diorite, and granodiorite which define an arc‐related calc‐alkaline suite. Zircon U‐Pb ages reveal that the complex was emplaced between ~50–47 Ma. Zircon Hf isotopes yield εHf(t) values of 8.2–13.1, while whole‐rock Sr and Nd isotopes yield εNd(t) values of 2.7–6.5 indicative of magmatism dominated by melting of a juvenile mantle source with only minor crustal assimilation (~15%–25%) as indicated by assimilation and fractional crystallization modeling. Together with published data, the early Eocene magmatic flare‐up was likely triggered by slab breakoff of subducted oceanic lithosphere at depths shallower than the overriding plate. The early Eocene magmatic flare‐up may have contributed to crustal thickening of the Gangdese arc. This study provides important insights into the magmatic flare‐up and its significant role in the generation of large batholiths during the transition from subduction to collision. [ABSTRACT FROM AUTHOR]

The Uhelchulu quartz diorite-granodiorite intrusions in Xiwuqi, Inner Mongolia, are exposed along the northwestern margin of the Xilinhot microcontinental block, located within the central and eastern parts of the southeastern Hegenshan suture zone. LA-ICP-MS zircon U-Pb dating yielded crystallization ages of (396 ± 8) Ma for the quartz diorite and (385 ± 5) Ma for the granodiorite, indicating an Early-Middle Devonian magmatic event. The quartz diorite exhibits I-type granite features, characterized by elevated Al2O3 (14.33–15.43 wt%), MgO (3.73–5.62 wt%), and Na (Na2O/K2O = 1.04–1.44), coupled with low P2O5 (0.15–0.20 wt%) and TiO2 (0.73–0.99 wt%). Trace element patterns show relative enrichments in Rb, Th, U, and Pb, while Nb, Ta, Sr and Ti are relatively depleted. Total REE contents are relatively low (123–178 ppm), with significant LREE enrichment (ΣLREE/ΣHREE = 4.75–5.20), and a non-obvious Eu anomaly (δEu = 0.75–0.84). In contrast, the granodiorite displays S-type granite characteristics, with high SiO2 (70.48–73.01 wt%), K (K2O/Na2O = 1.35–1.83), Al2O3 (A/CNK = 1.16–1.31), and a high differentiation index (DI = 76–82). Notably, MgO (1.44–2.24 wt%) contents are low, and significant depletions of Ba, Sr, Ti, and Eu are observed, while Rb, Pb, Th, U, Zr, and Hf are significantly enriched. Total REE contents are relatively low (178–314 ppm), exhibiting significant LREE enrichment (LREE/HREE = 6.17–8.36) and a pronounced negative Eu anomaly (δEu = 0.34–0.49). The overall characteristics point towards an active continental margin arc background for the Uhelchulu intrusions. Previous studies have suggested that the Hegenshan ocean continuously subducted northward from the Early Carboniferous to the Late Permian, but there is a lack of evidence for its geological evolution during the pre-Early Carboniferous. Therefore, this paper provides a certain basis for studying the geological evolution during the pre-Early Carboniferous in the Hegenshan ocean. We preliminarily believed that the Hegenshan ocean underwent a southward subduction towards the Xilinhot microcontinental block in the Xiwuqi area, at least from the Early Devonian to the Middle Devonian and the Hegenshan ocean may might have undergone a shift in subduction mechanism during the Late Devonian or Early Carboniferous. [ABSTRACT FROM AUTHOR]

Although considered a crucial component of the Rodinia supercontinent, it remains uncertain how the Yangtze craton relates to the accretion and breakup of Rodinia. Here, the Huanglingmiao granitic complex (HGC), an intermediate-acid rock series that intruded on the southern Kongling terrane of the northern Yangtze craton margin, is investigated to help resolve this conundrum. Our analysis indicates that these rocks consist of tonalite, trondhjemite, granodiorite, oligoporphyritic granodiorite, porphyric biotite granodiorite, and fine- to medium-grained granodiorite dyke compositions. Collectively, this assemblage is further subdivided into two categories by their temporal, spatial, and geochemical features into early TTG-like and later granitic–dioritic units, which are composed of tonalite, trondhjemite, granodiorite, porphyritic granodiorite, and the fine- to medium-grained granodiorite dykes, respectively. Zircon U-Pb dating yields ages of 865~850 Ma for the TTG-like rocks, 844~825 Ma for the porphyritic granodiorites, and ~800 Ma for the granodiorite dykes. Combined with geochemical evidence, the data suggest that the early- and late-series rocks were formed by a partial melting of Mesoproterozoic and Paleoproterozoic crustal materials, respectively, suggesting that the vertical layering of the crust controlled the composition of the independent units. In addition, isotopic evidence points to different sources for the various rocks in the Kongling terrane and that mantle-derived materials influenced the early-series lithologies. Combined with previous studies on the northern margin of the Yangtze craton, it is inferred that the early-series rocks formed in an active continental margin environment, while the late-series rocks display within-plate boundary formation characteristics. The multiple magmatic activities revealed by this study record sequential partial melting with tectonic transition characteristics from an Andean-type to within-plate magmatism in the northern margin of the Yangtze craton. Taken together, these observations point to a strong association between these rocks, convergence, and incorporation of the northern Yangtze craton margin into the Rodinia supercontinent during the Tonian Period. [ABSTRACT FROM AUTHOR]

The Neoproterozoic granitic rocks of Mount Abu Kibash and Tulayah in the central Eastern Desert of Egypt are of geodynamic interest and provide us with important information about the evolution and growth of the northern part of the Arabian–Nubian Shield (ANS) continental crust. They are primarily composed of granodiorites and syenogranites based on new field, mineralogical, and geochemical analyses. The granodiorites are marked by an enrichment of LILEs such as Sr, K, Rb, Ba compared to HFSEs like Nb, Ta, Ti and show a higher concentration of LREEs relative to HREEs. This composition suggests a subduction-related setting and aligns with the characteristics of subducted I-type granites in the ANS. Chemistry of the analyzed primary amphiboles in the investigated granodiorites support a calc-alkaline nature, mixed source and subduction-related setting. The granodiorites represent an early magmatic phase in this setting, likely formed from a mix of mantle-derived mafic magmas and lower crust material, with subsequent fractional crystallization. On the other hand, syenogranites exhibit high SiO2 (72.02–74.02 wt%), total alkali (7.82–8.01 wt%), and Al2O3 (13.79–14.25 wt%) levels, suggesting their derivation from peraluminous (A/CNK > 1) parental magmas. Their REE-normalized patterns are flat with a pronounced negative Eu anomaly, typical of post-collisional A2-type granites worldwide. These rocks originated from the partial melting of a juvenile lower crustal source (tonalite) in a post-collisional setting, driven by lithospheric delamination that facilitated mantle upwelling and underplating to the lower crust. Interaction between the upwelled mantle and lower crust led to fertilization (enrichment with HFSE and alkalis) of the lithosphere before partial melting. Fractional crystallization coupled with less considerable crustal assimilation are the main magmatic processes during the evolution of these rocks. The transition from subduction to post-collisional setting was accompanied by crustal uplifting, thickening and extensional collapse of ANS continental crust that caused emplacement of large masses of A-type granites in the northern ANS. [ABSTRACT FROM AUTHOR]

The Nellie Tonalite forms a discontinuous 20 km elongate northwest-trending felsic intrusion at the far-western end of the Western Zone of the Lamboo Province, in the Wunaamin Miliwundi Orogen, Western Australia. This intrusion is poorly understood with previous interpretations assigning it to the ca 1860 Ma Paperbark Supersuite. We present the first geochronological results for the Nellie Tonalite, which have a weighted mean laser ablation, inductively coupled plasma, mass spectrometry (LA-ICP-MS) U–Pb zircon age of 1794 ± 4 Ma. This date is coincident with the age for felsic granophyres of the Hart Dolerite, which have previously been described from the Kimberley Basin overlying the Halls Creek Orogen and central parts of the Wunaamin Miliwundi Orogen. Other similarities of the Nellie Tonalite with the felsic Hart Dolerite are micrographic and granophyric intergrowths of quartz and K-feldspar, and a distinct geochemical depletion of V. This V depletion is interpreted to be the result of closed-system, in situ fractional crystallisation of titanomagnetite from a basaltic composition. The fractional residue from this process can be found at several locations across the Halls Creek Orogen and Wunaamin Miliwundi Orogen and at Speewah Dome in the east Kimberley where magnetite gabbros within the Hart Dolerite also host a large Ti–V mineral resource. It is proposed that the Nellie Tonalite is a western correlate of the felsic Hart Dolerite. This demonstrates that the magmatic processes required for Speewah-style Ti–V mineralisation are extensive across the entire Lamboo Province. Additionally, the scale, constancy of the composition, texture and age of the felsic Hart Dolerite encompassing the entire inland margin of the Kimberley Region, and the rapid emplacement time of <3 m.y., support the interpretation of a mantle plume model for the emplacement of the Hart Dolerite. KEY POINTS: The Nellie Tonalite is redefined as a granophyric granite, has been dated to 1794 ± 4 Ma and is coeval with the ca 1800 Ma Hart Dolerite. Petrographic, geochemical and geochronological evidence suggests that the Nellie Tonalite is a product of in situ fractional crystallisation of the Hart Dolerite (felsic Hart Dolerite). Plots of Ti/Nb vs V/Sc are ideal in identifying the distinctive V-depletion associated with the felsic Hart Dolerite, which marks a valuable stratigraphic horizon for identifying potential Speewah-style Ti–V mineralisation. [ABSTRACT FROM AUTHOR]

The article presents the discussion on Hadani et al. (2024), who used geochemistry and isotopic data to classify the Azegour granite as I-type, suggesting its magma source originated from deep melting of mafic to intermediate rocks in the lower crust. Topics include the granite's geochemical similarity to I-type granitoids; and the possible magma source being influenced by mantle-derived basaltic melts.

The petrogenesis and geodynamic setting of the Mesozoic magmatic rocks in the Erguna Block, NE China remains controversial, especially the relationship between magmatism and the subduction history of the Mongol–Okhotsk oceanic plate. Here we present data for the Early Jurassic–Early Cretaceous adakite-like magmatic rocks from Chaoman Farm in the northeastern part of the Erguna Block. Zircon U-Pb dating reveals that the syenogranites crystallized at around 190–180 Ma, while the monzonites, quartz diorite porphyries, and quartz monzonite porphyries were emplaced at around 147–143 Ma. The syenogranites, monzonites, quartz diorite porphyries, and quartz monzonite porphyries are adakite-like rocks. The syenogranites and quartz monzonite porphyries were produced by the partial melting of a thickened ancient mafic lower continental crust and a thickened juvenile lower crust, respectively. Meanwhile, the monzonites and quartz diorite porphyries were formed as a result of partial melting of the oceanic crust. In conclusion, the occurrence of these Early Jurassic magmatic rocks was closely linked to the process of southward subduction of the Mongol–Okhotsk oceanic plate. On the contrary, the Late Jurassic to early Early Cretaceous magmatism (147–143 Ma) occurred in an extensional environment, and was probably triggered by upwelling of the asthenosphere. [ABSTRACT FROM AUTHOR]

This paper presents a detailed study including LA-ICP-MS zircon U-Pb dating, geochemical, zircon Hf isotope, and whole rock Sr-Nd isotope analysis of magmatic rocks from the Yitong County, Jilin Province, NE China. These data are used to better constrain the Middle Silurian–Middle Devonian tectonic evolution in the eastern segment of the northern margin of the North China Craton (NCC). Zircon U-Pb dating results show that the Ximangzhang tonalite formed in the Late Silurian (425 ± 6 Ma); the basalt, andesite, and metamorphic olivine-bearing basalt in the Fangniugou volcanic rocks formed in the Middle Silurian (428 ± 6.6 Ma) and Middle Devonian (388.4 ± 3.9 Ma, and 384.1 ± 4.9 Ma). The Late Silurian tonalites are characterized by high SiO2 and Na2O and low K2O, MgO, FeOT, and TiO2, with an A/CNK ratio of 0.91–1.00, characteristic of calc-alkaline I-type granite. They are enriched in Rb, Ba, Th, U, and K, and depleted in Nb, Sr, P, and Ti, with positive εNd(t) (+0.35) and εHf(t) (+0.44 to +6.31) values, suggesting that they mainly originated from the partial melting of Meso–Neoproterozoic accretionary lower crustal material (basalt). The Middle Silurian basalts are characterized by low SiO2, P2O5, TiO2, and Na2O and high Al2O3, FeOT, and K2O, enriched in Rb, Ba, Th, U, and K and depleted in Nb, Ta, Sr, P, and Ti, indicative of shoshonitic basalt. The Late Silurian tonalites have positive εNd(t) (+4.91 to +6.18) values and primarily originated from depleted mantle magmas metasomatized by subduction fluids, supplemented by a small amount of subducted sediments and crustal materials. The Middle Devonian volcanic rocks exhibit low SiO2, TiO2, and Na2O and high K2O, and MgO, enriched in Rb, K, and LREEs and depleted in Nb, Ta, Sr, and HREEs, characteristic of shoshonitic volcanic rocks. Their εNd(t) (+2.11 to +3.77) and εHf(t) (+5.90 to +11.73) values are positive. These characteristics indicate that the Middle Devonian volcanic rocks primarily originated from depleted mantle magmas metasomatized by subduction fluids, with the addition of crustal materials or subducted sediments during their formation. Based on regional geological data, it is believed that the study area underwent the following evolutionary stages during the Silurian–Devonian period: (1) active continental margin stage of southward subduction of the Paleo–Asian Ocean (PAO) (443–419 Ma); (2) arc-continent collision stage (419–405 Ma); (3) post-collision extension stage (404–375 Ma); (4) active continental margin stage, with the PAO plate subducting southward once again (375–360 Ma). [ABSTRACT FROM AUTHOR]

Integrated geochemical, U-Pb zircon, and Pb isotopic data from granitoids of the Wulandele porphyry molybdenum deposit, northeastern Inner Mongolia, are reported to disclose the possible magmatic process and Mo ore-forming process. LA-ICP-MS zircon U-Pb dating constrains the timing of the quartz diorite and monzonitic granite to 282 ± 2.4 Ma and 135.4 ± 2.1 Ma, respectively. The ages are accordant with geological facts which state that the shallow Permian granitoids are only the ore-hosting rock while the concealed Cretaceous fine-grained granite is the causative intrusion. Whole-rock geochemical data show that the granitoids belong to the high-K calc-alkaline series, and are enriched in LILEs, but depleted in HSFEs. Permian granitoids exhibit I-type characteristics, while Cretaceous granite is akin to A-type granite. Pb isotopic ratios are consistent between Permian granitoids and Cretaceous granite with ratios of 206Pb/204Pb = 18.048–18.892, 207Pb/204Pb = 15.488–15.571, and 208Pb/204Pb = 37.066–38.441. Considering geological and geochemical features together, Permian granitoids are interpreted as subduction-related continental margin high-K calc-alkaline rocks, while Cretaceous granite may be the result of the remelting of the relic Permian arc in an extensional environment induced by the rollback of the Paleo-Pacific plate. Different from classical porphyry-type deposits, the Wulandele Mo deposit, which formed in an intraplate tectonic setting, indicates that the intraplate porphyry Mo deposit should be one of the important exploration targets in the Central Asian Orogenic Belt, especially its eastern segment. [ABSTRACT FROM AUTHOR]

Mafic microgranular enclaves (MMEs), commonly found in granitoid intrusions, can provide unique perspectives on the nature of magma sources and evolution, physicochemical properties of magmas, and geotectonic dynamic evolution. However, their origin and generation remain under debate. In this paper, the Cretaceous Tongkeng pluton with MME occurrence located in the Xiaojiang area of Zhejiang Province, SE China, was examined. Zircon U-Pb dating indicates that the gabbroic diorite, MMEs, and their host quartz diorite all crystallized at 107-106 Ma. All samples from the Tongkeng pluton show a comparable range of initial 87Sr/86Sr values (0.70746-0.70841), eNd(t) values (-4.9 to -2.9), and zircon eHf(t) values (-7.3 to -2.9) with the peak value of - 6 to - 4. In addition, Pb isotope compositions are fairly consistent. Petrology, geochemical and isotopic compositions, and geochemical modeling suggest that the gabbroic diorite, MMEs, and their host rock were cognate and their primary magma was derived from the mixing between a mantle-derived magma and a crustal magma. The "magma differentiation and convection" model, proposed in this paper to improve our understanding of the origin of the MMEs and their host rock, suggests that the gabbroic and quartz dioritic magmas were formed by cognate magma differentiation, and the MME magma is a portion of the gabbroic dioritic magma that is incorporated into and mingled with the quartz dioritic magma. Misjudgment in the origin and generation of MMEs leads to an erroneous understanding of mantle properties, the genesis of granitoids, and therefore, many other geological processes. Hence, caution is needed when considering the relationship between the host granitoid and its associated MMEs with similar chemical and isotopic compositions, particularly for those exposed in areas where mafic rocks are absent (or undiscovered). [ABSTRACT FROM AUTHOR]

Introduction The Cenozoic Urumieh-Dokhtar magmatic arc has characteristics similar to those of Andean-type magmatic arcs. Various types of magmatism occurred in this arc including calc-alkaline and K-rich calc-alkaline magmatism and less of them alkaline magmatism (Shahabpour, 1982). Kerman porphyry copper belt (KPCB) in the southern part of this arc includes two types of granitoids: (1) Jebal Barez-type (late Eocene–early Miocene) associated with minor Cu-mineralization, and (2) Kuh Panj-type (middle Miocene–Pliocene), which is associated with major porphyry copper deposits (Mirzababaei et al., 2016). Kuh-kapout porphyry deposit (Eocene) in the southern part of KPCB is affected by Jebal Barez type granitoids. This deposit has been studied to determine the genesis of magmatism, mineralization and tectonic setting, by the whole rock geochemistry of quartz diorite intrusions, this evaluation is based on trace and REEs geochemistry data. Regional Geology This area is located in the southern part of the Urumieh–Dokhtar magmatic belt and in the Kerman porphyry copper belt. Arc-related magmatism events in this region include Paleocene to Oligocene magmatism and including andesite- dacite volcanic-sedimentary rocks with porphyry texture and quartz diorite intrusions with porphyry texture. In these rocks on the surface, there are intermediate argillic alteration events, and with increasing depth, quartz-sericite-pyrite zone and then potassic and alkali (potassium)-feldspar-sericite-chlorite-anhydrite zone are observed. Quartz diorite rocks include plagioclase and hornblende crystals (about 30 to 40 percent), biotite (10 to 15 percent), and potassium feldspar and quartz. Potassic alteration zone in depth is recognized by hydrothermal biotite, K-feldspar, magnetite and anhydrite. Mineralization in quartz diorite intrusions is more in the form of pyrite, chalcopyrite, and magnetite in association with the potassic alteration zone. Andesite-dacite volcanic-sedimentary rocks and quartz diorite rocks intruded by post-mineralized and barren micro diorite intrusion. Analytical method The samples were selected based on field observations and changes in mineralization-alteration rates from the weak alteration section of the quartz-sericite zone. For analyzing trace and rare earth elements, Samples were analyzed by the multi-acid method and used the Microwave Digest. Many of handpick and drill core samples were prepared to form thin sections for microscopic studies Alteration and mineralization In this area, different types of hydrothermal alteration events including potassic, phyllic, propylitic, argillic and K-feldspar- chlorite- sericite, occurred that was influenced by fractures and faults. Quartz diorite intrusive rocks shows intense potassic and phyllic alteration zone, the main type of hydrothermal alteration zone is potassic and contains quartz ± chalcopyrite ± pyrite ± magnetite as mineralized veins and scattered event of pyrite, chalcopyrite, and magnetite. The phyllic alteration zone includes pyrite, which increases with depth. In the quartz-sericite-pyrite alteration zone, abundant chlorite and plagioclase are observed in the groundmass along with the occurrence of pyrite and anhydrite, and Cu mineralization in the form of scattered chalcopyrite. Whole rock chemistry In this study, it seems that due to the presence of phases such as garnet and hornblende in the magma in the origin, a fractionation between HFSEs and LILEs has occurred (Green, 2006). Remaining of HFSEs and HREEs in the origin lead to low amounts of these elements in the resulting magma. The occurrence of negative anomalies in these elements, on the other hand, can be due to crustal contamination with mantle magmatism during their ascent to the surface. Anomaly in trace elements and ratios of REEs and trace elements, emphasizes that magmatism originated from the volcanic arc and subsequent events, according to the Th/Nb-Ba/Th diagrams and the La/Sm-Sm/Yb diagram, including the presence of lower crustal contamination and the significant role of fluid in the production of metasomatized magmatism. According to the studies on data normalized to the primary mantle, a depletion in Ba and Nb values and an enrichment in Rb and Cs have occurred. Discussion Studying trace and rare earth elements in porphyry copper deposits is useful for determining the mineralization and fertility of magmatism, tectonomagmatism-setting, crustal contamination, and mantle metasomatism. Th-Co diagram (Hastie et al., 2007) and Th/Yb-Ta/Yb diagram (Hastie et al., 2007) indicate that most of the samples in this study area were plotted in the calc-alkaline magma region of the diagrams. Using the Sm/Yb versus La/Sm diagram (Aldanmaz et al., 2000) in the quartz diorite rocks shows a magmatism with higher Sm/Yb ratios than what is usually found for the spinel lherzolite. The plotting of the samples on diagrams indicates that the samples are located near the spinel + garnet lherzolite trend, indicating that the early magmatism originated from the spinel + garnet lherzolite mantle. High values of Ba/Th compared to low values of Th/Nb emphasize the contamination of subducting material or lower crust with magma; the (Dy/Yb)CN-Sr/Nd (Kelemen et al., 2003) diagram indicated that the process of fractional crystallization of plagioclase was effective in the evolution of magma; and finally, the study of samples in this deposit shows the relatively high water content in the magmatism, associated with the presence of garnet in the source and magma contaminated with the lower crust (Temel et al., 1998). In order to investigate the tectonic environment of the deposit, the diagrams of Pearce et al. (1984) were used. The samples are located in the active continental margin and associated with collision magmatism. Conclusions analysis of the trace and REEs of the quartz diorite rocks in the region, a magmatism related to the arc with the calc-alkaline series can be recognized. In terms of the evolution of magmatism, according to the interpretation of trace element data, from the origin to the surface, it can be considered a magmatism that originated from the partial melting of magma with the metasomatized spinel + garnet lherzolite composition in the source with the presence of garnet and amphibole phases. In terms of geochemical properties magmatism is more similar to Kuh-Panj type granitoid than the Jabal Barez type; and it is placed in the category of semi-economic to economic magmatism. Based on studies of trace elements from whole rock data, the tectonomagmatism of the rocks in the region is in the range of the active continental margin to collision setting. [ABSTRACT FROM AUTHOR]

The East Kunlun Orogen is a giant magmatic tectonic activity belt and an important part of the Central Orogenic Belt of China. It has superior mineralization conditions and remarkable mineralization phenomena, and has always attracted the attention of some geologists. The Lalangmai Tungsten Mine is located in the Chahanwusu River area in the eastern section of the East Kunlun Orogen and is under the jurisdiction of Huishui township, Dulan county, Qinghai province. It is a newly discovered skarn-type deposit in recent years. This article takes the Lalangmai tungsten deposit as the research target. Purpose: The purpose of the research is to establish a geological-geochemical exploration model to guide the deployment of prospecting for the tungsten deposit in the Lalangmai area. Method: The research method was selected based on the comprehensive analysis of the mineralization geological background, the geological characteristics of the mining areas, and the characteristics of the surface soil geochemical anomalies, and further summarized the geological-geochemical prospecting mark, thereby constructing a geological-geochemical exploration model. Result: The main conclusions obtained from the research include; W-Sn-Mo-Au-Ag-As-Sb elements have a strong correlation, while other elements have a poor correlation. The currently discovered tungsten ore bodies(mineralized bodies) mainly occur in skarn rocks. The contact zone between tonalite diorite and Baishahe formation strata is the most favorable location for finding tungsten ore. The northeast-southwest trending structural fracture zone is an ore-containing structure. The metal minerals in the tungsten ore bodies are mainly scheelite, followed by wolframite. Conclusion: Based on the geological-geochemical exploration model constructed in the article, 3 prospecting target areas were delineated in the Lalangmai area, including 1 Class- I prospecting target area and 2 Class- II prospecting target areas. In addition, it is expected that the deep areas and the peripheral areas of the mining area have great prospecting potential. More geological exploration work arrangements should be implemented. The innovation of this article is the systematically constructed geological-geochemical exploration model, which has achieved good prospecting results in the Lalangmai tungsten mining area and achieved a breakthrough in prospecting for tungsten deposits in the eastern section of East Kunlun Orogen, and has provided a new prospecting and exploration path for searching for the same type of tungsten deposits in the area. [ABSTRACT FROM AUTHOR]

The Gangdese metallogenic belt in Tibet is an important polymetallic metallogenic belt formed during the subduction of the Neo-Tethys Ocean and subsequent India–Asia collision. Adakitic rocks are widely distributed in this belt and are considered to be closely related to porphyry–skarn Cu-Mo polymetallic mineralization. However, the petrogenesis and geodynamic setting of the Late Cretaceous adakites in the Gangdese belt remain controversial. In this study, we focus on the quartz diorite in the Nuri Cu-W-Mo deposit along the southern margin of the eastern Gangdese belt. LA-ICP-MS zircon U-Pb dating yields a Late Cretaceous age of 93.6 ± 0.4 Ma for the quartz diorite. Whole-rock geochemistry shows that the quartz diorite possesses typical adakitic signatures, with high SiO2, Al2O3, and Sr contents, but low Y and Yb contents. The relatively low K2O content and high MgO, Cr, and Ni contents, as well as the positive zircon εHf(t) values (+6.58 to +14.52), suggest that the adakites were derived from the partial melting of the subducted Neo-Tethys oceanic slab, with subsequent interaction with the overlying mantle wedge. The Late Cretaceous magmatic flare-up and coeval high-temperature granulite-facies metamorphism in the Gangdese belt were likely triggered by Neo-Tethys mid-ocean ridge subduction. The widespread occurrence of Late Cretaceous adakitic intrusions and associated Cu mineralization in the Nuri ore district indicate a strong tectono-magmatic-metallogenic event related to the Neo-Tethys subduction during this period. This study provides new insights into the petrogenesis and geodynamic setting of the Late Cretaceous adakites in the Gangdese belt, and has important implications for Cu polymetallic deposit exploration in this region. [ABSTRACT FROM AUTHOR]

The Fe skarn and vein-type Cu mineralization types are common in the Eastern Taurus Mountains. This study aims to determine the U-Pb geochronology of garnets of varying sizes within the skarn zone developed at the quartz diorite–marble contact zone in Ayazpınar, Pertek District, Tunceli Province, Turkey. Additionally, this study aims to determine the age of the skarnization and the types of inclusion minerals in the garnets. Faulting and magma emplacement along the thrust plane caused mineralization in the Eastern Taurus Mountains, especially at the marble and quartz diorite contact zone between the cities of Elazığ and Tunceli. The greenish garnets found in the Ayazpınar deposit are characteristic of distal skarns, while red or brown Pertek garnets are observed in the proximal skarns. The garnets typically feature a core–rim texture. The cores of the garnet crystals are large, reddish in color, and have a high REE (Ce, Pr) content. Moreover, the cores have higher Fe and lower Al ratios, alongside higher La, Ce, and Pr contents, than the rims. We propose that the compositional differences between the rims and the cores reflect the transition from oxidized REE- and Fe3+-rich liquids to liquids with lower REE and Fe3+ contents, producing the differences in the garnet colors. Green garnets show lower REE contents than brown garnets with Fe-rich cores. The skarn under study includes the following successively formed zones: diorite → epidote skarn → garnet–magnetite → pyrite–garnet–magnetite → calcite carbonate. Diopside, magnetite, and hematite, including small grains, are surrounded or enveloped by garnets. The U-Pb age of the mineralization is 74.1 ± 5 Ma, indicating that the mineralization occurred concurrently with the intrusion settlement. [ABSTRACT FROM AUTHOR]

Granite genesis is crucial to understanding the evolution of continental crust, yet many concerns about granite genesis remain not well answered, such as whether I-type granite contains metasedimentary components, what controls granite compositional diversity, and how granitic plutons are constructed. To explore these issues, we conducted a detailed study on the two-mica plagiogranite, tonalite, and biotite plagiogranite units of the Wujinxia composite pluton in the eastern Qilian orogen, NE Tibetan Plateau. These units comprise two-mica plagiogranite, tonalite (with diorite enclave), and biotite plagiogranite. Zircon U–Pb data reveal that three granitic units formed at ~ 487 Ma, ~ 464 Ma, and ~ 430 Ma, respectively. Magmatic and xenocrystic garnet were identified from the tonalite and biotite plagiogranite, respectively. The two-mica plagiogranite, tonalite, and biotite plagiogranite all belong to low-K series rocks (K2O/Na2O = 0.10–0.26), and were derived from deep crustal sources mainly consisting of juvenile mafic rocks, with involvement of minor metasedimentary rocks in the magma sources of the two-mica plagiogranite and tonalite. The diorite enclave within the tonalite was probably derived from an enriched mantle-derived basaltic magma. Mineral compositions, thermobarometric calculations, and whole-rock geochemical data indicate that the low-K intrusive units of the Wujinxia composite pluton resulted from multiple magmatic systems at different depths. The results suggest that I-type granites can contain metasedimentary components by partial melting of a mixed crustal source, and high-Mn content helps the preservation of high-Ca garnet within such rocks. For a composite pluton spanning a large compositional variation, its compositional diversity is jointly controlled by magma source composition, melting condition and thermal evolution of individual magma pulses, and the resulted assembly style during pluton construction. [ABSTRACT FROM AUTHOR]

The oldest granitoids of the Kan–Chingiz Complex with quartz diorites, granodiorites, plagiogranites, and granites are dated for the first time in the Chingiz–Tarbagatai region of eastern Kazakhstan. The U‒Pb (ID-TIMS and SIMS) age of granites and plagiogranites is 509 ± 2 and 512 ± 3 Ma, which corresponds approximately to the Early–Middle Cambrian boundary. These data indicate the Early Cambrian age of volcanosedimentary sequences host granitoids. The peculiarities of the composition of granitoids of the Kan–Chingiz Complex point to their formation within an ensimatic island arc. [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 Jiama deposit, a significant porphyry‐skarn‐type copper polymetallic deposit located within the Gangdese metallogenic belt in Tibet, China, exemplifies a typical porphyry metallogenic system. However, the mineral chemistry of its accessory minerals remains under‐examined, posing challenges for resource assessment and ore prospecting. Utilizing electron microprobe analysis and LA‐ICP‐MS analysis, this study investigated the geochemical characteristics of apatite in ore‐bearing granite and monzogranite porphyries, as well as granodiorite, quartz diorite, and dark diorite porphyries in the deposit. It also delved into the diagenetic and metallogenic information from these geochemical signatures. Key findings include: (1) The SiO2 content, rare earth element (REE) contents, and REE partition coefficients of apatite indicate that the dark diorite porphyry possibly does not share a cogenetic magma source with the other four types of porphyries; (2) the volatile F and Cl contents in apatite, along with their ratio, indicate the Jiama deposit, formed in a collisional setting, demonstrates lower Cl/F ratios in apatite than the same type of deposits formed in a subduction environment; (3) compared to non‐ore‐bearing rock bodies in other deposits formed in a collisional setting, apatite in the Jiama deposit exhibits lower Ce and Ga contents. This might indicate that rock bodies in the Jiama deposit have higher oxygen fugacity. Nevertheless, the marginal variation in oxygen fugacity between ore‐bearing and non‐ore‐bearing rock bodies within the deposit suggests oxygen fugacity may not serve as the decisive factor in the ore‐hosting potential of rock bodies in the Jiama deposit. [ABSTRACT FROM AUTHOR]

The western Argentinian sector of Gondwana has been the focus of several recent studies related to the Famatinian orogeny; however, the geologic history of arc activity in hinterland areas remains poorly understood. We present new data from the Monte Guazú Complex that reveal arc-related magmatism in the Sierras de Córdoba, which we consider part of the Famatinian hinterland. Igneous rocks comprise a diorite unit which includes an amphibole quartz-gabbro/diorite and a tonalite unit comprising amphibole- and biotite-bearing tonalites to minor granodiorites. Both units constitute a medium-K calc-alkaline series ranging in composition from metaluminous to moderately peraluminous. Trace-element signatures show Ti and Nb depletion and strong incompatible element enrichments (large-ion lithophile elements, Pb, Th, U, and light-rare earth elements) relative to normal mid-ocean ridge basalts, suggesting that they formed in an arc setting. U–Pb zircon geochronology constrains magmatism to 455–498 Ma, while weighted mean ages of 474–489 Ma are mostly synchronous with the Famatinian arc beginning. We demonstrate that fractional crystallization of mantle wedge-derived melts controlled the early magmatic evolution, while country rock assimilation and anatectic melt mixing were prevalent in evolved rock members. These results spatially extend the Late Cambrian–Late Ordovician Famatinian retro-arc to the southern Sierras de Córdoba. Our findings show that magmatism involved coeval anatexis of host rocks, conversely to previous geodynamic models. Our data have fundamental implications for Paleozoic tectonic and magmatic processes operating along the western Argentinian sector of Gondwana, demonstrating the importance of crustal reworking and the addition of mantle material in the Famatinian arc inboard sector. [ABSTRACT FROM AUTHOR]

The Gangdese belt in Xizang has experienced both Jurassic subduction and Cenozoic continental collision processes, making it a globally renowned region for magmatic rocks and porphyry copper deposits. Numerous Jurassic intrusions have been identified in the belt. Apart from the quartz diorite porphyry in the large Xietongmen deposit, the Cu mineralization potential of other Jurassic intrusions in this belt remains unclear. This study presents zircon U–Pb dating and trace elements, apatite major and trace elements as well as published whole-rock geochemical and isotopic data of the Dongga tonalite in the central part of the Gangdese belt, aiming to reveal the petrogenesis, oxidation state, volatile content, and Cu mineralization potential of this intrusion. The Dongga tonalite has a zircon U–Pb age of 179.4 ± 0.9 Ma. It exhibits high whole-rock V/Sc values (8.76–14.6), relatively low apatite CeN/CeN* ratios (1.04–1.28), elevated zircon (Eu/Eu*)N values (an average of 0.44), high Ce4+/Ce3+ values (205–1896), and high ∆FMQ values (1.3–3.7), collectively suggesting a high magmatic oxygen fugacity. The Dongga tonalite features amphibole phenocrysts, relatively high whole-rock Sr/Y ratios (20.3–58.9), and lower zircon Ti temperatures (502–740 °C), reflecting a high magmatic water content. Estimation of magmatic sulfur content (0.002–0.024 wt%) based on apatite SO3 contents indicates an enriched magma sulfur content. Combined with previous studies and the collected Sr–Nd–Hf isotopes, the Dongga tonalite is derived from juvenile lower crust related with subduction of the NeoTethys oceanic slab. When compared with Xietongmen ore-bearing porphyries, the Dongga tonalite exhibits remarkable similarities with the Xietongmen ore-bearing porphyries in terms of magma source, tectonic background, magmatic redox state, and volatile components, which indicates that the Dongga tonalite has a high porphyry Cu mineralization potential, and therefore, provides important guidance for the future mineralization exploration. [ABSTRACT FROM AUTHOR]

The timing and extent of sulfide saturation have been suggested as controlling factors in the formation of economically significant porphyry Cu deposits in subduction zone settings. However, details on the sulfide saturation history in post-collisional porphyry systems remain ambiguous. Accordingly, we have characterized the whole-rock geochemistry, including platinum-group elements (PGE), of igneous intrusions in the post-collisional Chongjiang porphyry Cu–Mo–Au deposit (southern Tibet) and utilize this data in conjunction with zircon U–Pb geochronological results and sulfide chemistry to assess the timing of sulfide saturation, the nature and amount of magmatic sulfide produced. The Chongjiang intrusions (monzogranite, biotite monzogranite porphyry, granodiorite, dacite porphyry, and quartz diorite porphyry) and mafic microgranular enclaves (MMEs) have zircon U–Pb ages of 14.2 to 12.8 Ma. Covariations in whole-rock major and trace elements among the Chongjiang intrusions and MMEs, together with similarities in their Sr–Nd and zircon Hf isotope compositions, indicate that they are co-magmatic and crystallized from a juvenile lower crustal melt that mixed with mafic melt derived from the lithospheric mantle; this hybrid melt subsequently evolved via fractional crystallization. Trace-element ratios in zircon and temperature − ∆FMQ estimates of the different intrusions suggest that they all crystallized from oxidized (average ∆FMQ = 1.9–2.6) and water-rich magmas. Palladium contents and Pd/Pt ratios in the Chongjiang igneous intrusions increase with decreasing MgO up to 3.9 wt % MgO, after which they abruptly decrease. The initial increase in Pd/Pt ratios likely results from the fractionation of a Pt-rich mineral (e.g. Pt–Fe alloy). The decrease in Pd contents and Pd/Pt ratios at 3.9 wt % MgO likely results from sulfide saturation during magma evolution, but prior to volatile exsolution, which occurred at approximately 1.4 to 2.4 wt % MgO. The presence of magmatic sulfide inclusions in amphibole and magnetite in samples with 3.9 wt % MgO, and the geochemical compositions of sulfide inclusions suggest that they represented trapped sulfide liquid and intermediate solid solution. Results of Monte Carlo simulations demonstrate that 0.003 to 0.009 wt % magmatic sulfide is required to have fractionated from the magma to explain the decrease in Pd contents at 3.9 wt % MgO. Highly chalcophile elements, such as Pd, will be sequestered by the magmatic sulfide that saturates at depth, decreasing their concentrations in the residual silicate melt, whereas concentrations of the less chalcophile elements, such as Cu, Mo, and even Au, will not be as significantly affected. Consequently, sufficient concentrations of Cu–Mo–Au will remain in the residual melt and, upon reaching volatile saturation, can be transported by the vapor phase to form porphyry Cu–Mo–Au deposits. In the case of the Chongjiang deposit, sulfide saturation was likely triggered by the high pressures and/or depletion of FeO caused by the thick (~70 km) crust beneath the Gangdese belt. This contribution presents evidence of sulfide saturation in post-collisional magmatic systems, and demonstrates that the amount of magmatic sulfide produced is a critical factor in controlling the formation of post-collisional porphyry Cu deposits. [ABSTRACT FROM AUTHOR]

The article presents the discussion on Loudaoued et al. (2024) by clarifying key issues related to the Azegour granite's classification, emphasizing the similarities to I-type granitoids and incorporating additional data for comparison. Topics include the importance of understanding magmatic activity ages in the Marrakech High Atlas; and details on various age constraints from early Cambrian to Permian periods.

The large magma reservoirs underlying world-class porphyry deposits are one of the key factors in their formation, which thus led to the present study focusing on the unmineralized intrusive rocks underlying the porphyry molybdenum-copper orebody of the post-collisional Jiama porphyry-skarn copper-polymetallic deposit in southern Tibet. The Jiama porphyry intrusion comprises intermediate-silica quartz diorite, monzogranite, and granodiorite porphyries, as well a high-silica granite porphyry. The intrusive rocks suite exhibits similar whole-rock Sr-Nd isotopic compositions [εNd(t) = -3.9 to -0.8], suggesting a common, non-radiogenic magma source. Yet, these rocks have distinct geochemical characteristics. The intermediate-silica rocks are relatively enriched in Ba and Sr with minor Eu anomalies, and show adakite-like geochemical characteristics. In contrast, the high-silica granite porphyry is strongly depleted in Ba, Sr, and Eu, and lacks adakite-like geochemical characteristics. We propose that the high-silica granite porphyry represents highly fractionated melt extracted from a silicic mush reservoir (crystallinity of ∼40%-65%), and that the monzogranite and granodiorite porphyries constitute the complementary residual silicic cumulates. High crystallinity facilitates the formation of connected fluid pathways, allowing the efficient removal of volatiles from the remaining silicic melt and a rapid flux of the ore-forming fluids toward the apical parts of the large magma reservoir. Less-evolved mafic melt is believed to have repeatedly intruded the base of the magma reservoir, thereby releasing volatiles and water into the silicic mush systems. The volatiles migrated upward through the fluid channels and accumulated in the apical part of the magma reservoir, subsequently, as a result of the overpressure in the roof zone, ore-forming fluids and successive batches of magma were expelled together, thereby forming the Jiama porphyry-skarn deposit. [ABSTRACT FROM AUTHOR]

The eastern part of the Central Asian Orogenic Belt in NE China is one of the world's well-known Ag-Pb-Zn-Mo metallogenic provinces, and the late Mesozoic magmas have been considered to supply dominant metals for mineralization. However, Cu mineralization in this belt is relatively rare. The Zhalageamu deposit is a newly discovered copper deposit in this region and could be applied to address the issue of whether the regional late Mesozoic magmatism could have triggered the formation of large Cu deposits. The quartz diorite and granite porphyry in Zhalageamu returned laser ablation-inductively coupled plasma-mass spectrometric (LA-ICP-MS) zircon U-Pb ages of 267.1 ± 2.0 Ma and 255.6 ± 2.2 Ma, respectively. Molybdenite coexisting with chalcopyrite yielded an isotope dilution-negative-thermal ionization mass spectrometric Re-Os age of 141.8 ± 0.8 Ma. This age is almost identical to that of the coexisting arsenopyrite within the analytical uncertainty, which yielded an Re-Os isochron age of 140.7 ± 5.9 Ma. The above ages constrain the timing of Cu mineralization to the late Mesozoic. The fact that the Cu mineralization is >110 m.y. younger than its igneous host rocks precludes a genetic link between them. Instead, the Cu mineralization age indicates that a possible hidden late Mesozoic intrusion likely contributed Cu mineralization. The age of the Zhalageamu deposit is similar to that of the late Mesozoic magmatic-hydrothermal Ag-Pb-Zn-Fe-Sn mineralizing event (140-120 Ma) in NE China. This suggests that the Zhalageamu Cu mineralization was part of this event and implies the broader existence of a late Mesozoic magmatic-hydrothermal Cu mineralizing event in NE China, a discovery that would be of great significance for further Cu exploration. [ABSTRACT FROM AUTHOR]