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Earth's long-term history is preserved in the rock archive, yet this record is incomplete, hindering our understanding of how tectonic processes have evolved and shaped our planet's evolution. The physio-chemical resilience of zircon and its ability to be rapidly analyzed for age, isotopic, and elemental data has made it a key phase in unraveling Earth's long-term evolution. The europium anomaly (Eu/Eu*) and the differentiation degree between light and heavy rare earth elements (LREE N ¯ / HREE N ¯) of zircons positively correlate with the pressure of magma crystallization because high pressure inhibits plagioclase crystallization and promotes garnet growth. However, this correlation can be influenced by fluctuations in redox conditions, protolith composition, and water content of magma, whose stability varies in different tectonic settings. Therefore, the correlation coefficient between Eu/Eu* and LREE N ¯ / HREE N ¯ of detrital zircons (r Dz) provides a new proxy to help distinguish tectonic settings. We evaluate this new proxy using available global detrital zircon REE data from different tectonic settings in modern and deep times. The data from well-constrained simple tectonic settings suggest that r Dz is higher in convergent settings (0.53–0.85) than in collisional settings (0.12–0.51). Convergent settings can also yield relatively low r Dz (0.28–0.55) when there is a contribution of a mantle plume lying below the overriding plate of a subduction zone. When studying a detrital zircon archive derived from a large distributive province that includes sources from a variety of settings, known provenance information should be used to disentangle mixed source signals. Also, only considering detrital zircon grains that formed a short time (e.g., 50 or 100 Myr) prior to deposition can reduce the likelihood of multi-cycle distal mixing of contemporaneous but tectonically distinct zircons in a sample. Additionally, greater confidence in interpretations of changes in tectonic settings may be derived from evolution patterns of r Dz instead of isolated values. A decreasing trend can likely be interpreted as a transition from convergent to collisional or mantle plume settings, whereas an increasing trend implies an opposite tectonic transition. [Display omitted] • Detrital zircon rare earth element data have the potential to reflect tectonic processes. • The r Dz is the correlation coefficient between Eu/Eu* and LREE N ¯ / HREE N ¯. • The r Dz is higher in convergent settings than in collisional or mantle plume settings. [ABSTRACT FROM AUTHOR]

The generation of voluminous SiO 2 -rich magmas has been extensively investigated due to their petrologic implications and because they pose a significant natural hazard. Two main petrogenetic models have been proposed to explain these volcanic products: partial melting of the continental crust and fractional crystallization and assimilation of mantle-derived magmas. In the central segment of the modern Colombian magmatic arc, the northernmost Andean magmatic arc, the eruption of voluminous rhyolitic pyroclastic rocks occurred at 2.6 Ma, covering an area of ∼3000 km2. This contribution presents Hf-Nd-Sr-Pb whole-rock isotopes, zircon U Pb geochronology, and major/trace-element data from Pliocene rhyolitic ignimbrites and Quaternary andesitic lava flows from the modern Colombian magmatic arc to understand the mechanisms responsible for the formation of high-silica magmas. The whole-rock and zircon geochemistry and Nd-Sr-Pb-Hf isotopic signatures indicate that this high-silica magmatism is mantle-derived and underwent extensive crystal fractionation and limited assimilation of the continental crust. Extreme magma fractionation at low temperatures and crustal thicknesses above 45 km could have favored the production of cumulates and fast (< 5 Ma) crustal thickening. These results highlight the major role of the mantle in generating high-silica magmatism and the associated crustal thickening, a process that has been poorly understood in the Northern Andes. • Basaltic magmas as a precursor of SiO 2 –rich magmatism and arclogite formation. • Voluminous SiO 2 –rich magmatism controlled by mantle input. • Crustal thickening controlled by magmatism instead of shortening in Northern Andes. [ABSTRACT FROM AUTHOR]

Plagioclase ultraphyric basalts (PUBs) are an important unit of the Abor magmatic complex (AMC) of the eastern Himalaya, containing ≥35 vol% plagioclase phenocrysts. Apart from the eastern region, PUBs have not been reported in any other part of the Himalayas. However, very little information is available about their origin and significance in the evolution of the eastern margin of the Indian plate and the Himalayan orogeny. In this contribution, we present the first zircon U Pb age data of the PUBs along with whole-rock geochemistry, Sr Nd isotopic ratios, mineral chemistry, and quantitative textural analysis, to understand the evolutionary history of the AMC and subsurface magma chamber activities. The PUBs formed from highly evolved magma (<6 MgO wt%), having high Fe 2 O 3 (9.06–12.29 wt%) and Ti/Y ratios (>500). Their εNd (t) values (−0.02 to +2.66) suggest plume magma source. A small difference in anorthite contents (<5 mol%) is observed from the thick core (An 47–58) with lower anorthite contents towards the rim (An 34–47) of the plagioclase phenocrysts, which is an indication of weakly zoned characteristics. Crystal size distribution shows a non-linear and concave upward trend with a relatively gentler slope towards the coarser plagioclase populations, which can be attributed to the hybrid crystallization of plagioclase-bearing magma and its subsequent differentiation with cumulates of plagioclase inside the magma chamber. The zircon U Pb age of these PUBs records two magmatic events - Early Paleozoic (505–473 Ma) at the core and Early Cretaceous (134–126 Ma) at the rim that are consistent with the previously proposed magmatic events of AMC with Gondwana assembly and break-up. Encounter of such dual ages in zircons does not support the usual condition of PUBs formation through crystal floatation in a slow cooling process of a single magma chamber. Therefore, considering the evidences observed in crystal size distribution, core-rim anorthite variation, geochemistry, and age data, we propose that the PUBs of AMC, eastern Himalaya were formed due to injection of a hot and young magma during the Early Cretaceous into an old and cold mush zone containing pre-existing plagioclase phenocrysts formed during the Early Paleozoic. The results further support that the newly injected magma formed the rim of the plagioclase phenocrysts and the groundmass of the PUBs. • First successful attempt to date the PUBs of Eastern Himalaya by zircon U Pb method. • Zircon U Pb yield two magmatic events - 505-473 Ma and 134–126 Ma for PUBs. • Whole-rock geochemistry point towards an enriched mantle source. • Plagioclase textural indicates a complex magmatic history. • PUBs formed by injection of new magma to an older magma chamber. [ABSTRACT FROM AUTHOR]

In the African section of the Paraná-Etendeka Large Igneous Province (LIP), several early Cretaceous intrusive complexes with highly variable bulk rock compositions ranging from subalkaline to alkaline‑carbonatitic are strikingly aligned on a SW-NE trend and are clearly related to the large igneous province that straddles Africa and South America based on their 40Ar/39Ar and Rb–Sr ages. We use high-precision zircon U–Pb geochronology, zircon Hf isotope compositions, and bulk-rock and zircon geochemistry of these intrusions to decipher the spatial pattern of magmatism and the mechanisms of magma formation and evolution. High-precision CA-ID-TIMS zircon ages show that the plutons were emplaced without clear spatial systematics over at least 1.4 Myr from 133.2 to 131.8 Ma and likely postdate the peak of volcanic activity in the southern Etendeka (Namibia) and the Paraná (Brazil), estimated to be between 135 and 133 Ma. The youngest Damaraland zircon ages overlap with previously reported baddeleyite ages for mafic dykes and sills in the southern Paraná, confirming that magmatism in the whole LIP continued beyond 132 Ma. In the whole Damaraland province, intrusive rocks follow two distinct evolution paths towards both the granite/rhyolite and the syenite/phonolite minima. The near-synchronous emplacement of silicic to highly alkaline bodies with no clear spatial or temporal pattern is best explained by lithospheric extension driven by mantle upwelling along reactivated lineaments accommodating active N-S rifting of the South Atlantic. Negative zircon εHf(t) values in silicic complexes (−5 to −12) likely stem from crustal contamination during ascent of primitive mafic melts via "path contamination" and/or from a heterogenous mantle source already contaminated by recycled crustal material ("source contamination"). Similarly variable, but on average less negative zircon εHf(t) in alkaline and carbonatitic intrusions (0 to −6) reflect source contamination and preferential low degree melting of fertile portions in a heterogenous mantle source. These mantle heterogeneities likely originate from recycling of ancient lithosphere during subduction in the Neoproterozoic, or from fertile material brought up by the Tristan-Gough mantle plume via intrusion and/or exposed by lithospheric erosion, fertilizing the lithospheric mantle under the Damaraland prior to and during the main flood basalt event. • High-precision U–Pb ages for the Damaraland intrusions range from 133.2 to 131.8 Ma. • Magmatism in the Paraná-Etendeka LIP continued beyond 132 Ma. • Importance of lithospheric extension in LIP formation. • Evidence for mantle source contamination by subduction or mantle plume interaction. [ABSTRACT FROM AUTHOR]

The Late Carboniferous Gharabagh-Mamkan-Mingol plutonic complex (GMMP) consists of a variety of ultramafic, mafic, felsic intrusive rocks, including the 325–315 Ma Gharabagh gabbroic, granitic, and monzonitic rocks and Mamkan-Mingol 320–315 Ma massive appinites (hornblende-rich gabbros) and 300–295 Ma layered mafic-ultramafic (gabbro, appinitic gabbro, and appinite) rocks in the northwestern Sanandaj-Sirjan zone, Iran. The relationships between various rock types in the plutonic complex are unknown. To address these issues, we conducted a detailed petrologic and geochemical study of the complex, and its country rocks. The abundance of major and trace elements and isotopic ratios of 87/86Sr (0.70379–0.70428) and 143/144Nd (0.51228–0.51245) systems showed that the Gharabagh gabbros formed from a metasomatized amphibole-bearing spinel lherzolite from an ancient subduction-modified mantle source with OIB characteristics including high contents of light rare earth elements (LREEs), Ti, Nb, Ta, and Ba, as well as low concentrations of Sr, Hf, and Zr. The geochemical data show that monzonites had high concentrations of LREEs, Ba, U, K, Hand Zr, and the low contents of Th, Nb, Ta, Sr, P, and HREEs and Eu-positive anomalies and originated from the melting of the continental crustal base in the subducted mantle wedge. The granites are similar to monzonites, with their difference being in the high concentrations of Th and Eu-negative anomalies. Combining petrographic, petrological, geochemical, and isotopic data suggests that Gharabagh plutonic rocks were formed as a result of Paleo-Tethys slab break-off, and slab sinking, during trans-tensional collision between the Central Iranian microplate and Gondwanaland during the Late Carboniferous. As a result of this event, decompression melting began in the upwelling mantle, coeval with the formation of the pull-apart basin, during major strike-slip faulting, leading to a hydrous mafic melt with about 10–12% partial melting. The Mamkan-Mingol massive and layered masses have a tholeiitic affinity. The Mamkan-Mingol rocks are characterized by different trace element patterns, especially in the concentrations of REEs and high field strength elements (HFSEs) such as Nb, Ta, Hf, Zr, and P and large-ion lithophile elements (LILEs) such as Th, U, Sr, K, Rb, and Ba. The massive and layered rocks mostly show a variably developed negative anomaly in HFSEs, and widely varying ratios of (La/Yb) n (1.0–5.2). Massive appinites and layered gabbros of GMMP originated due to different partial melting in the upwelling zone of metasomatized OIB-like amphibole-bearing spinel lherzolite and a less hydrous- to dry upwelling mantle zone, respectively, in an environment associated with the initiation of rifting, where the remnants of the Paleo-Tethys subducted slab plunges deep into the mantle. Contrasting Nd isotopic ranges are present between the massive appinites (ɛNd = +0.39) and different types of mafic-ultramafic rocks in layered outcrops (ɛNd = +1.12 to +2.07) of the complex. Based on the geochemical and isotopic (ratios of Sr, Nd, and Pb) data, we suggest that variations in of contribution of slab-derived fluids or crustal components in the primary melt caused the generation of massive appinites and different types of layered gabbros. [Display omitted] • The main mass of the Gharabagh-Mamkan-Mingol plutonic complex (GMMP) formed during 325-295 Ma. • The intrusion formed during the collision between the Central Iranian microplate and Gondwanaland. • Ancient fluids and remnants of Paleo-Tethys oceanic lithosphere facilitated the generation of mafic to felsic melts. • The main factor for the petrological diversity of GMMP is fractional crystallization with simultaneous crustal assimilation. [ABSTRACT FROM AUTHOR]

Sedimentary rocks can provide important insights regarding the evolution of Earth's surface environments through deep time. Such sequences are pervasive through the geological record and currently cover >70% of the planet's surface. They are also a key repository for energy and mineral resources. However, absolute chronology of sedimentary rocks can be difficult to constrain using conventional methods due to their typically low abundances of radiogenic elements. Establishing chronology is particularly challenging for Precambrian sedimentary rocks, where the lack of a diverse fossil record makes biostratigraphic correlations ambiguous. In this study, we use shale and carbonate samples from the Proterozoic greater McArthur Basin in northern Australia as a case study to demonstrate two emerging in-situ laser-based methods that have the potential to quickly and accurately resolve the minimum depositional age of a sedimentary package. The first method provides a tool to constrain the formation of authigenic clay minerals in shales using in-situ laser ablation Rb Sr geochronology. The second method demonstrates an approach for dating carbonate sedimentation using U Pb geochronology via a laser isotopic mapping approach. Laser rasters are compiled into isotopic maps, and this spatial and geochemical information is used to target representative subdomains within the sample. Detrital or altered regions can be avoided by monitoring chemical signatures and pixels, and to the most authigenic domains are then subdivided that give the best spread of data on an isochron. Both approaches provide the key advantage of preserving, and through the mapping approach further resolving, sample petrographic context, which together with complementary geochemical data can be triaged to yield a more appropriate age and interpretation. [Display omitted] • The U Pb image mapping approach can time the formation of sedimentary carbonates. • Authigenic clays in shales can be dated by in situ Rb Sr geochronology. • Both approaches combine geochemical and spatial data to isolate cogenetic phases. [ABSTRACT FROM AUTHOR]

The widely distributed Devonian granitoids comprise a significant part of the crust in the Chinese Altai, although their petrogenetic implications remain debated. The Habahe Intrusion, comprising biotite granite batholith, gabbroic diorite dikes, and biotite granite hosted-enclaves, is a key magmatic unit to understand the extensively developed magmatism in the Chinese Altai. To investigate their petrogenesis and tectono-magmatic significance, this study presents comprehensive petrological, geochronological, and geochemical studies on the Habahe Intrusion. The geochronological results indicate that the enclaves and the host biotite granite share similar ages (395.1 ± 3.7 Ma, MSWD = 4.5 and 395.1 ± 2.5 Ma, MSWD = 0.21, respectively), and slightly older than the gabbroic diorite dikes (378 ± 4 Ma), suggesting the Devonian magmatism. The biotite granite (SiO 2 = 73.9%–76.4%) is amphibole-bearing and shows I-type granite affinity. The enriched zircon Hf (εHf(t) = +2.5 to +5.4), near zero whole-rock Nd (εNd(t) = −1.0 to −0.3) and intermediate Sr isotopes (Isr = 0.7058–0.7072) suggest their generation from the partial melting of the lower crust. The enclaves display variable mineral proportions (amphibole dominated to quartz dominated), major (SiO 2 = 48.6%–62.4%, Mg# = 34.3–67.0), trace element compositions (ΣREE = 20.0–194.5 ppm) and Sr Nd isotopes (εNd(t) = −0.6 to +4.1, Isr = 0.7023–0.7055), indicating their hybrid nature. Together with the acicular apatite and quenched rims of the enclaves, they show a magma mixing event. Nevertheless, the biotite-rich rims of the enclaves and the homogenous compositional and isotopic characteristics of the host biotite granite suggest limited mixing/mingling. The gabbroic diorite dikes (SiO 2 = 48.8–52.4%), consisting of amphibole and plagioclase, display E -MORB-like trace and rare earth element patterns and have depleted Hf (εHf(t) = ∼ + 9), Nd (εNd(t) = +1.7 to +7.3) and low Sr (Isr = 0.7045–0.7089) isotopes, pointing to an asthenosphere mantle origin. Combining these, we propose a model suggesting that the biotite granite was generated by melting of the lower crust, trigged by upwelling of the asthenosphere mantle during subduction. The mafic magma, derived from the partial melted asthenosphere mantle, mixed weakly with the felsic magma from the partial melted lower crust, thereby supplied limited mantle materials for the generation of the biotite granite batholith. This study offers important insights into the extensive Devonian tectono-magmatic processes in the Chinese Altai. [Display omitted] • The gabbroic diorite dikes were derived from the partial melting of asthenosphere mantle in hydrous condition. • The biotite granite crystallized from a common magma derived from the partial melting of the lower crust. • Limited mixing/mingling occurred between mantle-derived mafic magma and crustal-derived felsic magma. • Habahe Intrusion traces the extensive magmatism during the subduction in the Chinese Altai. [ABSTRACT FROM AUTHOR]

The Archean basement in the Yinshan Block of the western North China Craton consists of a variety rock of assemblage, including TTG (tonalite-trondhjemite-granodiorite) rocks and some dioritic gneiss (sanukitoid). Understanding the petrogenesis of these rocks is crucial for comprehending the late Neoarchean crustal evolution of the western North China Craton. This study provides a new geochronological, geochemical, and Sr-Nd-Pb-Hf isotopic data for the TTG-sanukitoid suit that was newly identified in the Zhulagou area. The late Neoarchean TTG gneisses were emplaced around 2.54–2.50 Ga, while dioritic gneiss was emplaced between 2.53 and 2.50 Ga. The TTG gneisses exhibit high SiO 2 (64.46–72.24 wt%) and Al 2 O 3 (13.37–16.48 wt%) contents, relatively elevated (La/Yb) N and Sr/Y ratios, as well as low Y and Yb contents. They display variable ε Hf (t) (+0.94 to +3.57) and ε Nd (t) (−1.02 to +0.82) values, with relatively low Pb isotopic compositions, suggesting that they were derived from the partial melting of a thickened mafic lower crust. On the other hand, dioritic gneiss shows moderate SiO 2 (58.05–61.87 wt%) content, high MgO (2.62–4.06 wt%), Al 2 O 3 (14.42–18.44 wt%) and Cr contents, but relatively low (La/Yb) N values, showing geochemical affinity to the Archean sanukitoids. The dioritic gneiss exhibits variable ε Hf (t) values (−2.29 to +5.56) and ε Nd (t) (−2.05 to +2.02), with relatively low Pb isotopic compositions. Furthermore, the presence of amphibolite xenoliths, along with the high Mg# contents (36.84–53.49), indicating the addition of mantle-derived components to its source region. Therefore, the formation of the dioritic gneiss is primarily attributed to partial melting of the thickened (mafic) lower crust and the addition of mantle material. By combining previous studies with the new data presented in this study, we propose that a late Neoarchean tectonic regime involving a mantle plume is the most favorable explanation for the two major magmatic events in the Yinshan Block. Firstly, the earlier pulse/stage of mantle plume resulted in the ∼2.7 Ga thickened (mafic) lower crust and a limited amount of TTG rocks. Subsequent pulse/stage of mantle plume triggered partial melting of pre-existing thickened (mafic) lower crust and generated 2.54–2.50 Ga TTG rocks and dioritic gneiss. • TTG gneisses and dioritic gneiss were emplaced at 2.54-2.50 Ga. • TTG gneisses and dioritic gneiss derived from partial melting of the thickened (mafic) lower crust. • The Yinshan Block experienced ~2.7 Ga and 2.5 Ga magmatic events that were mainly controlled by a Neoarchean mantle plume regime. [ABSTRACT FROM AUTHOR]

The Pamir Plateau contains critical information on the tectonic evolution of the Tethys domain. In this study, we report geochronology, geochemistry, and Sr-Nd-Hf isotopic compositions of the Cenozoic adakitic monzogranite in the Reskam and Taxkorgan areas, NE Pamir, to provide new insights into the post-collisional tectonic evolution following the India-Eurasian collision. Zircon U Pb ages reveal these granitoids were emplaced at ca 12–8 Ma. Geochemically, they exhibit relatively uniform whole-rock major and trace element compositions, and share typical adakitic signatures with high SiO 2 (68.55–73.30 wt%), moderate Al 2 O 3 (14.11–15.84 wt%), elevated Sr (399–1710 ppm) and La (34–182 ppm), but low Y (5.53–15.10 ppm) and Yb (0.39–1.26 ppm), and thus in high Sr/Y (32−200) and (La/Yb) N ratios (20–236). Isotopically, these adakitic rocks show significantly enriched whole-rock Sr Nd (ε Nd (t) = −7.97 to −5.76; 87Sr/86Sr(t) = 0.7072–0.7110) and zircon Hf (mostly ε Hf (t) -5 to −2) isotopic compositions. Elemental and isotope signatures indicate their origin from partial melting of mafic-intermediate sources under high pressure, with a residuum of negligible feldspar but dominant garnet. Integrating the new findings with reported data of granitoids in the Pamir, we estimate the crustal thickness variations from the Cretaceous to Miocene. The crustal thickness in the Pamir region largely remained no more than 45 km before India-Asia collision, after which a significant increase in crustal thickness occurred, reaching a peak of 80–100 km around 10 Ma. We propose that the break-off of the subducted Neo-Tethys oceanic slab (ca. 40 Ma) and lithospheric delamination (ca. 25 Ma) led to two-stage rapid continental uplift events in Pamir Syntax. • Miocene adakitic monzogranites are identified in the NE Pamir. • The adakitic rocks are generated by melting of thickened lower crust. • Crust thickness variation in Pamir Syntax during 120–10 Ma is estimated. [ABSTRACT FROM AUTHOR]

This paper presents new field, petrographic, geochemical, Sr Nd isotopic and geochronological data from Kestanbol Magmatic Complex (KMC) in the western Anatolia. Zircon U Pb ages from the KMC were in the range 21.91 Ma and 21.52 Ma, indicating Miocene emplacement. 40Ar/39Ar dating results of biotites from the same samples show a narrow range of ages between 20.0 and 22.7 and a weighted mean of 21.41 ± 0.40 Ma, and those of hornblende analysis yield ages between 21.52 and 31.19 Ma with a weighted mean of 22.70 ± 0.99 Ma, are interpreted as the cooling age of the KMC. The average (U-Th/He) ages from the KMC yielded an average of 21.5 Ma and 19.8 Ma. These new age data indicate rapid cooling following the emplacement of the KMC at ∼21 Ma. We suggest that the cooling was due to rapid uplift in the western Anatolia. The studied monzonitic, syenitic and alkaline subvolcanic rocks of the northern KMC are characterized by high K 2 O (4.34–10.7 wt%), low to moderate SiO 2 (50.0–69.9 wt%), and P 2 O 5 (0.03–1.07 wt%). They have moderate initial 87Sr/86Sr (0.707245–0.707875) and high initial 143Nd/144Nd (0.512441–0.512508) ratios, consistent with some crustal contamination. The studied rocks are enriched in Th (up to 204 ppm), U (up to 54.9 ppm), REE (up to 565.9 ppm) and, some LILE's including K (up to 8.85%), Rb (up to 447.1 ppm), Sr (up to 2053 ppm) and Ba (up to 2578 ppm). The geochemical and isotopic data suggest that the magmatic evolution of KMC is dominated by events including post-collisional tectonics, flux induced partial melting, fractional crystallization. The enrichments of incompatible elements are mostly caused by the fractional crystallization and K-metasomatism that affected the earlier magmatic phases during the cooling of the complex. • Kestanbol Magmatic Complex (KMC) is emplaced during a post-collisional regime. • The KMC is a product of partial melting and fractional crystallization processes. • The Northern KMC rocks are enriched in Th-U ± REE that caused by a K-metasomatism. • The thermochronology show that KMC emplaced in Miocene and cooled rapidly. [ABSTRACT FROM AUTHOR]

The Southern Great Xing'an Range (SGXR) in Northeast China is a significant polymetallic mineralization belt. Although several beryllium (Be) deposits have been reported in the SGXR, the timing and mechanisms of Be mineralization are poorly understood. To determine the mechanisms of newly-discovered Be mineralization in the Madumeng area, we carried out monazite–zircon–apatite U–Pb dating, whole-rock and mineral geochemical, and monazite Nd isotopic analyses of the beryl-bearing quartz veins and host Late Permian–Early Triassic granite. Monazite from the beryl-bearing quartz veins yielded U–Pb ages of 138–137 Ma, and the host granite yielded zircon and apatite U–Pb ages of 251 ± 1 and 256 ± 27 Ma, which indicate that the Madumeng Be mineralization formed later than the host granite. Monazite in the beryl-bearing veins has similar ε Nd (t) values (−1.31 to +4.27) to those of Early Cretaceous highly fractionated granite related to Be mineralization in the SGXR, which suggests the ore-forming material was derived from exsolved fluids associated with Early Cretaceous, deep-seated, highly fractionated granites. Fluid-rock reactions had a key role in generating the Madumeng Be mineralization, and the intensity of these reactions was recorded by the whole-rock and mineral geochemistry. The alteration during fluid-rock reactions increased the pH and Ca contents of the fluids. Mica and beryl record the release of Ca and Fe from the granite into the fluid. The released Ca2+ ions combined with F− ions in the fluid, leading to instability of Be–F complexes and subsequent precipitation of beryl. Our findings indicate that the Early Cretaceous was an important period of Be mineralization in the SGXR and highlight the contribution of fluid-rock reactions to Be precipitation in quartz vein-type Be mineralization. • Madumeng beryl veins preserve within Late Permian–Early Triassic granite. • Beryllium derived from exsolved fluids of seated Early Cretaceous granites. • Increased Ca2+ and pH led to Be–F complex instability and beryl precipitation. [ABSTRACT FROM AUTHOR]

The Larvik Plutonic Complex is a monzonitic complex that was emplaced early during the formation of the Permian Oslo Rift (southern Norway). It extends across its entire width (around 50 km), and is made up of a majority of larvikite (augite monzonite) and lardalite (nepheline monzogabbro to nepheline syenite) distributed in ten successive intrusive units that partially intersect each other. The Larvik Plutonic Complex also hosts occurrences of singular Fe-Ti-P-rich rocks of magmatic origin, including the Kodal deposit. These are mainly composed of titanomagnetite, ilmenite, titanaugite and apatite, the latter also featuring rare earth elements (REE) enrichment. Here, we aim to unravel the conditions that allowed the Kodal deposit to form, and determine why other mineralized bodies are not seen elsewhere in the Larvik Plutonic Complex. We compared the petrography and elemental and isotope (Sr, Nd and Hf) geochemistry of both the Kodal mineralization and the neighboring larvikite, in order to provide evidence of their petrogenetic relationship. Both lithologies share the same isotopic ratios (87Sr/86Sr (i) : 0.7035–0.7043; εNd (i) : +2.37 − +3.48; εHf (i) : +3.39 − +9.16), which would suggest a single homogeneous source. The very low dispersion of our isotopic data also suggests that crustal contamination levels in the area were low to negligible. Normalized trace diagrams of larvikite in several localities of the Larvik Plutonic Complex also show enrichments in most incompatible elements, which becomes more prevalent towards the Kodal deposit. Elements like Sr and Eu(2+) follow an opposite trend, because of their compatibility in plagioclase. We therefore infer that the region around the Kodal deposit hosts more fractionated larvikite due to the previous crystallization of successive plagioclase cumulates. We deduce that the Kodal lobe corresponds to a more evolved intrusion, which is no part of Pluton V per se, as considered in the literature until now, but instead derives at least from a monzonitic magma at the origin of the plutons V to VIII). This also implies that the formation of Fe-Ti-P mineralization at Kodal was most likely a consequence of enrichment of the residual melt in alkaline elements and incompatible elements. These conditions support an early hypothesis of formation by silicate-liquid immiscibility, along with petrographic evidence of disequilibrium at the mineralogical scale. However, further analyses would be required to test the hypotheses of silicate-liquid immiscibility against an accumulation of the Fe-Ti-P mineralization from an evolved intermediate magma. • The Larvik Plutonic Complex contains evolved monzonite intrusions. • The region of Kodal in the Larvik Plutonic Complex contains a Fe-Ti-P deposit. • The Kodal Fe-Ti-P deposit formation is linked to an evolved monzonite body. • We suggest it might have formed by silicate-liquid immiscibility. [ABSTRACT FROM AUTHOR]

The Sieggraben Complex (SC) in Eastern Austria provides comprehensive information on the pre-Permian, Permian, and Alpine (Cretaceous) evolutional stages of the crustal and mantle sections included into the Austroalpine basement HP/UHP belt. The SC in the Sieggraben–Schwarzenbach area consists of three, top-to-bottom tectono-stratigraphic units: (1) the Paragneiss unit, (2) the Marble–Eclogite unit, which contains MORB and OIB types of mafic rocks, and (3) the Micaschist–Calcschist unit. The N-MORB type mafic rocks yield a U Pb age of 369.7 ± 2.0 Ma, have ε Nd(370) = +8.5 to +7.4 and TDM (2st) of 0.42–0.50 Ga, while the E-MORB types (U Pb ages around 400 Ma) show ε Nd(400) = +9.4 to +5.6 and TDM (2st) of 0.37–0.67 Ga, both indicating rather juvenile mantle sources during the formation of the inferred oceanic Devonian basin. The rocks of these units revealed Cambrian, Proterozoic, and Archean zircon sources. The ages of 285.8 ± 9.2 and 265.7 ± 2.1 Ma from eclogite and amphibolite, respectively, and 265.5 ± 1.4 Ma from paragneiss indicate an important Permian metamorphic overprint. Permian granitic dykes dated from ∼265 to 260 Ma, exceptionally at 273 and 253 Ma, crosscut the lithological units. A clinopyroxenite dyke, which crosscuts harzburgite of the underlying mantle fragment, yielded a magmatic age of 253.3 ± 2.9 Ma. Overall, these ages suggest a strong Permian extension, overheating, and melting of the crustal and mantle rocks. The eclogite ages from ∼100 Ma, but mainly between 92 and 90 Ma, constrain the Late Cretaceous metamorphic event terminated by an 88.4 ± 0.8 Ma pegmatite intrusion in the Paragneiss unit. The Permian and Cretaceous metamorphic events often caused resetting of the relatively older zircon ages, together with a decrease of zircon ε Hf(t) values, and an increase of whole-rock 87Sr/86Sr values. A Carboniferous metamorphic age of ∼340 Ma was rarely detected. The SC finally represents a part of an early Late Cretaceous intra-continental subduction zone, which formed within a strongly-thinned crystalline basement due to the Devonian and Permian extensions. A similar Cretaceous suture zone with HP amphibolite, dated at ∼130–100 Ma by white mica Ar Ar ages (100–90 Ma exhumation), has been described around the Lubeník line between the Gemeric and Veporic tectonic units of the Inner Western Carpathians in the framework of the Cenozoic AL–CA–PA (Alpine–Carpathian–Pannonian) microplate. • Lithology and geochemistry of the Austroalpine Sieggraben Complex • U Pb zircon geochronology of the pre-Alpine and Alpine events • Perturbation of Pb–Th–U, Sr, and Hf isotopic systems in metamorphic rocks • Permian metamorphism and the formation of granitic and pyroxenitic rocks • Cretaceous MP–HP/MT metamorphic rocks intruded by pegmatite [ABSTRACT FROM AUTHOR]

Cenozoic (≥ 43 Ma) silica undersaturated (potassic) trachybasalts and trachyandesites in southwestern Madagascar (Tsianihy-Manja, southern Morondava Basin) form a small monogenetic volcanic field emplaced above Paleogene detritic sedimentary rocks, along a NE-SW-trending fault system. These olivine-chromite±clinopyroxene-phyric primitive lavas (Mg# = 69; MgO = 10–11 wt%; Cr = 450 ppm, Ni = 200 ppm; K 2 O = 3–4 wt%) have highly peculiar trace element and isotopic composition (e.g., Ba/Nb = 18.4; 87Sr/86Sr i = 0.70529–0.70555, 143Nd/144Nd i = 0.51262–0.51263, 206Pb/204Pb m = 18.415–18.424, 207Pb/204Pb m = 15.576–15.579, 208Pb/204Pb m = 38.799–38.813). A hitherto undescribed plug of primitive (sodic) basanite of the 11–12 Ma-old Ankililoaka district south of Tsianihy-Manja (hosting spinel lherzolite mantle xenoliths) has noticeable different geochemistry (Ba/Nb = 8–9.2; 87Sr/86Sr i = 0.70346–0.7036, 143Nd/144Nd i = 0.51281–0.51282, 206Pb/204Pb m = 19.079–19.374, 207Pb/204Pb m = 15.621–15.645, 208Pb/204Pb m = 39.115–39.424). The relatively low CaO, Sc, V, Fe 2 O 3t , MnO at high MgO, Cr and Ni, and the potassic affinity of the Tsianihy-Manja trachybasalts, all indicate that the mantle source is relatively clinopyroxene-poor (i.e., depleted by previous melt extractions), in the same way as the source of lamproitic (or boninitic) magmas, but the primitive nature, the concentration of high field strength elements, the incompatible element patterns and their isotopic ratios indicate their unequivocal within-plate setting and indicate a derivation by low-degree partial melting of an incompatible element-enriched mantle and insignificant role for crustal contamination. In terms of incompatible element concentrations, and thus also Sr-Nd-Pb-isotopic composition, we find no evidence in favour of a mid-ocean ridge basalt (MORB)-mantle component, or for a MORB-mantle strongly enriched by ocean island basalt-like components, to form the mantle source regions of the Tsianihy-Manja and Ankililoaka mafic alkaline rocks. The significant isotopic change from the northernmost Cenozoic volcanic rocks of Madagascar and those in the central and southern part of the island (which range in composition from sodic to potassic, and from tholeiitic basalt to olivine melilitite) implicates a distinct source heterogeneity, and ultimately assess the role of the old continental lithospheric mantle as source region. • Cenozoic potassic and sodic mafic rocks in southwestern Madagascar • Mantle sources of potassic magmas is relatively clinopyroxene-poor. • No crustal contamination during magma ascent • Significant role of heterogeneous lithospheric mantle in generating alkaline melts [ABSTRACT FROM AUTHOR]

The Sierra de Mamil Choique calc-alkaline granite batholith, covering an area of 320 km2, serves as the key reference for Late Paleozoic magmatism in central-west Patagonia. It comprises I-type weakly to mildly peraluminous tonalites to granites (59.6–75.7%SiO2) displaying various deformational features. This paper presents a micro- and mesostructural study alongside temperature-pressure (T-P) constraints coupled with U-Pb zircon crystallization ages, as well as Ar-Ar and K-Ar mica ages, and mineral and whole-rock geochemistry. The older units (288 ± 1 Ma Cerro Mojón Monzogranite and 281 ± 2 Ma Huenchuquil Granodiorite), exhibit syn -kinematic banding and strong NW-SE foliation showing a transition from magmatic-sub magmatic to high-T subsolidus deformational features, such as parallel alignment of magmatic minerals, sub magmatic fractures, melt pockets, and chessboard subgrains in quartz. Quartz recrystallization by grain boundary migration is also observed. These microstructures developed concurrently with the regional D3 event that affected the Devonian metamorphic host. Their crystallization started at 8 Kbar and ∼ 790 °C within a thickened crust (La N /Yb N = 13–15, average). In contrast, the younger units (278 ± 2 Ma; Nahuelfil and Antinao Monzogranites) exhibit mainly magmatic deformation and display a NE-SW parallel alignment of mostly subhedral K-feldspar. A D4 deformation younger than 278 Ma, with a sigma 1 NW-SE (in plain view- horizontal) would have controlled the emplacement of Nahuelfil and Antinao Monzogranites. Younger zircon ages (ca 265 Ma) in the 278 Ma monzogranites would result from resetting due to the magmatic-hydrothermal alteration associated with the later magmatic pulse of leucogranites and pegmatites of the 267 ± 8 Ma (Rb-Sr WR isochron) La Pintada Leucogranites. These leucogranites were emplaced in an already thinner crust (La N /Yb N = 2.6 average). The latest magmatic activity is represented by two groups of pegmatitic bodies one from 265 ± 6 to 257 ± 3 Ma and a younger one of ca. 252–251 Ma (Ar-Ar and K-Ar muscovite cooling ages). All units share a common mafic source, but the younger units crystallized from melts at lower pressure and temperature (748–725 °C). The magmatism, involving crustal recycling, occurred at an active margin during a stage of thickened crust from 290 to 280 Ma, followed by gradual thinning after 280 Ma. This change in crustal thickness fits models proposing a continuous Permian subduction with a variable dip angle of the subducted slab along the southwestern margin of Gondwana. [Display omitted] • Gondwanide orogeny in Sierra Mamil Choique reached its magmatic climax in 288–265 Ma • Regional D3, bracketed between 290 and 280 Ma, is controlled by a horizontal NE-SW σ1 • Older units are syn -kinematic with D3 by its NW-SE banding and foliation • Post 295 Ma, a mostly mafic source in magmatism with upper crustal contamination • Crustal recycling results from a relatively thick crust in active continental margin [ABSTRACT FROM AUTHOR]

The central Tibetan Plateau, particularly the Bangong–Nujiang suture zone, hosts abundant and complex Late Mesozoic geological records and world-class mineral resources. However, intense debate persists about the origin and tectonic setting of these geological records and mineral resources, which impedes a comprehensive understanding of regional Late Mesozoic tectonic evolution and mineralization. In this study, we investigated the petrochronology, geochemistry, and Sr-Nd-Hf isotopic characteristics of ∼120 Ma magmatic rocks in this region. We explored their petrogenesis and sources, and in conjunction with their spatiotemporal distribution and scale, we facilitated a first proposal that these magmatic rocks were derived from ∼120 Ma hotspot–subduction zone interaction and that world-class mineral deposits were formed in this geological setting. This study is the first to identify geological records of hotspot–subduction interaction in the central Tibetan Plateau and it has significant implications for gaining a deeper understanding of the closing processes of the Late Cretaceous Epoch in the Meso-Tethys Ocean. This study also highlights the substantial contribution of this hotspot–subduction zone interaction to the formation of world-class mineral deposits in the region, and thus has crucial significance for guiding mineral exploration in the central Tibetan Plateau. • The hotspot–subduction zone interaction was found in the central Tibetan Plateau. • The hotspot–subduction zone interaction occurred in the Early Cretaceous (∼120 Ma). • Duolong mineral district was probably formed by hotspot–subduction zone interaction. [ABSTRACT FROM AUTHOR]

The Cenozoic Himalayan granites are widely accepted as the anatectic products of crustal rocks. However, previous geochemical studies on their petrogenesis are mainly based on whole-rock analyses. Here we conducted a detailed petrographic, trace elemental and Sr isotopic investigations of apatite from the Middle Eocene (44–40 Ma) two-mica granites and subvolcanic porphyritic leucogranites of the Yardoi-Lhunze complex from the Tethyan Himalayan Sequence in the southeast Tibet, with the aim to constrain their magma sources and petrogenetic processes. The results show that apatites from the Quedang and Dala two-mica granites are characterized by euhedral to subhedral crystal shape, and have a wide range of initial 87Sr/86Sr ratios (0.7016–1.0088). They show significant negative Eu anomaly and varied concentrations of Sr and Y, indicating they are typical magmatic apatites. Apatites from the Qiaga porphyritic leucogranites can be divided into two groups based on Eu anomaly. Group-I apatites with positive Eu anomaly mainly display euhedral to subhedral crystal shape but with alteration rim, suggesting from the influence of hydrothermal fluids. Group-II apatites with negative Eu anomaly also have euhedral to subhedral crystal shape but they exhibit patchy or oscillatory zones, consistent with a magmatic origin. However, both group-I and II apatites have comparable initial 87Sr/86Sr ratios, 0.7198–0.9966 and 0.7174–0.9999, respectively. Previous studies based on whole-rock petrology and geochemistry have suggested that the Quedang and Dala two-mica granites and the Qiaga porphyritic leucogranites represent cumulates and fractionated melt-rich magmas, respectively. This is evidenced by systematic variations between Sr, Y, (La/Sm) N and Eu/Eu* in magmatic apatites from Quedang and Dala, consistent with the fractionation crystallization of plagioclase and monazite. Apatite has a wide range of initial 87Sr/86Sr ratios (0.7016–1.0088), far exceeding the range of whole-rock records (0.7011–0.7204). Notably, most of the analyzed apatites show lower range of initial 87Sr/86Sr ratios consistent with locally exposed amphibolites (0.7109–0.7332). The remaining small portion of apatites have initial 87Sr/86Sr ratios falling within the data range of the locally exposed metapelites (0.8517–0.9527). Therefore, the investigated granites have mixed magma sources dominated by amphibolites with subordinate metapelites. This can be inferred by apatite Sr isotopes alone, but not by whole-rock Sr isotopes alone. Our investigations highlight that in-situ geochemistry of apatite can provide a powerful means to unravel the mixed magma sources and complicated magmatic processes for granites. • Apatite in-situ geochemistry is used to address petrogenesis of the Himalayan granites • Apatite trace elements document fractional crystallization until fluid exsolution • Apatite Sr isotopes records mixed magma sources [ABSTRACT FROM AUTHOR]

The Mesozoic tectono-thermal evolution of eastern South China plays an important role in forming the abundant magmatic rocks and associated giant polymetallic deposits. The middle-late Mesozoic granitoids in Mufushan and adjacent regions (e.g., Lianyunshan, Wangxiang, Taohuahsan, etc.) represent the western front of the southeast China magmatic province. However, the tectonic regimes and petrogenesis of the magmatic rocks are still elusive. Here, we report zircon U Pb ages, geochemistry, and Sr-Nd-Hf-Pb isotopic data for the granitic rocks in the Mufushan region, in combination with data available from the literatures, to discriminate the middle-late Mesozoic tectono–magmatic history of the Mufushan complex in north-central South China Block. New zircon U Pb dating suggests that the Mufushan two-mica monzogranites were emplaced at 149–144 Ma, a short time after the 153–151 Ma granodiorites. These late Jurassic felsic magmas share broad similarities in geochemical-isotopic characteristics, with significant enrichment in LREEs and LILEs (e.g., Ba, Rb, Th, and K), depletion in some HFSEs (e.g., Nb, Ta, Ti, and P) and positive Pb anomalies, similar to those of arc-type rocks. The common existence of Neoproterozoic zircons within the magmatic rocks indicates a certain amount of ancient material involved in the genesis of the magma. The two-mica monzogranites have ε Hf (t) values ranging from −13.4 to +3.5, overlapping with those of the granodiorites (−11.3 to +6.6), but both are lower than contemporaneous diorites (−2.4 to +0.59), suggesting a greater incorporation of enriched materials into the source for the granitoids. The two-mica monzogranites and granodiorites have ε Nd (t) values ranging from −7.9 to −8.8 and − 10 to −7.9, with corresponding two-stage Nd model ages of 1.7–1.6 Ga and 1.6 Ga, respectively, falling within their two-stage Hf model ages of 2.0–1.4 Ga and 1.8–1.4 Ga, respectively. Compared with the geochemical and isotopic compositions of the coeval magmatic rocks in eastern South China, we favor that the late Jurassic Mufushan granodiorites evolved from variable mixing and differentiation of the diorites and granitoids, accompanied by a continuous magma assimilation. The presence of late Jurassic highly fractionated granites suggests an extensive magma differentiation in eastern South China and the well-developed early Cretaceous A-type granites in eastern South China reflect a dominant extensional tectonic regime induced by slab roll-back of the Izanagi plate. The involvement of subduction-related melts facilitated the underplating of mantle-derived magma and crustal heating, triggering intensive partial melting of the lithosphere and magma enrichment, as well as the polymetallic deposits in eastern South China. [Display omitted] • The late Jurassic granitic rocks in Mufushan were derived from a common source. • Neoproterozoic crustal materials were involved in middle-late Mesozoic magmatism. • Mesozoic magmas were subjected to significant modification by slab-derived components. • The slab-roll back of the oceanic Plate beneath ESCB likely began by the middle Jurassic. [ABSTRACT FROM AUTHOR]

Arc-related plutonic rocks in southern Mexico occur along the Pacific coast in the Sierra Madre del Sur (SMS) igneous province. These rocks record the migration of the Caribbean–North America–Farallon/Cocos junction towards the east between the Late Cretaceous and Miocene. However, little is known about the petrogenesis of igneous rocks that were emplaced during the latest expressions of magmatism in the SMS (i.e., early–middle Miocene). Based on fieldwork, petrography, whole-rock and mineral geochemistry, thermobarometric calculations, and zircon U Pb dating, we document the petrogenetic evolution of the Jalapa del Marqués pluton and adjoining intrusions, which are the youngest so far dated in the SMS and are located ∼150 km inland from the present-day trench. This subduction-related magmatic complex consists of granites, granodiorites, diorites, dacite porphyries, and intermediate-to-felsic dikes, whose geochemical features suggest early evolutionary processes driven by fractionation of amphibole ± clinopyroxene (moderate–high pressures) or plagioclase (low pressures). Pulses of evolved magmas were episodically injected into upper-crustal reservoirs (7–14 km) over ∼9 Myr, starting at 22.14 ± 0.65 Ma (2σ)—earlier than previously thought (∼15.7 Ma)—and producing subsequent pulses at 19.45 ± 0.36 Ma, from 16.36 ± 0.37 to 15.8 ± 0.34 Ma, and from 13.9 ± 0.5 to 13.3 ± 0.2 Ma. These ages correlate with the onset and early stages of volcanic centers in the Trans-Mexican Volcanic Belt (TMVB), some of which were located up to 500 km landward from the present-day trench. The large difference in the distance-to-trench between coeval magmatism in the Jalapa del Marqués pluton and the TMVB, indicates a variation in the subduction angle between two segments of the Farallon/Cocos Plate that were likely separated by a slab-tear. The eastward migration of this slab-tear (along with the triple junction) terminated the magmatic activity in the SMS by switching the locus of magmatism to the TMVB. This probably occurred shortly after the studied magmatic complex was assembled. • The Jalapa del Marqués pluton records the amalgamation of episodic magma pulses. • Magma injections from deep-crustal reservoirs consolidated upper-crustal mushes. • Subduction-related magmatism evolved in a normal-to-thickened crust. • The late Sierra Madre del Sur was coeval with the early Trans-Mexican Volcanic Belt. • Extinction of the Sierra Madre del Sur was caused by the migration of a slab-tear. [ABSTRACT FROM AUTHOR]

The genesis of leucogranite magmas is important issue of geodynamics, petrology and ore geology because leucogranites are associated with collisional belts, partial melting of sedimentary source rocks, and may host rare metal (Sn, W, Li, Nb Ta, and Be) mineralization. To establish the petrogenesis of large leucogranite intrusions, detailed studies of petrography, mineralogy, fluid regime, and the material and isotopic composition of rocks are required. The paper reports results of the studies of the Delbegetei massif of the intrusion in Eastern Kazakhstan. The massif is composed predominantly of leucocratic granites, while syenogranites are subordinate. Rocks of the massif belong to shoshonitic and high-K calc-alkaline series; demonstrate a predominance of K over Na, high ferroan and high contents of LREE and HFSE; which allows them to be classified as A-type granites. The age of Delbegetei massif, estimated by the U Pb zircon dating, varies in the range 249–240 Ma, which correspond the Early-Middle Triassic. The differences in rock composition and in temperatures of zircon saturation allow supposing that syenogranites and leucogranites formed from different parental magmas. Syenogranite magma formed as a result of partial melting of metamorphosed volcanic rocks (andesidacites or dacites) with possible influence of mafic magmas. Leucogranite magma formed as a result of fluid-present partial melting of metaterrigenous sedimentary rocks. Leucogranite magma underwent the feldspars differentiation in the fluid-present conditions. This led to composition variations of leucogranites. Analysis of the geological position, age and composition of the rocks allows concluding that the Delbegetei massif formed at the Early Triassic in an intraplate geodynamic setting and that the activity of the Siberian mantle plume is the most probable reason for their formation. • The Delbegetei massif is composed of the A-type syenogranite-leucogranite series. • The meta-volcanic rocks are possible source for syenogranites. • The metasedimentary rocks are possible source for leucogranites. • The age of massif is Early-Middle Triassic (249–240 Ma). • The Siberian LIP is the most probable reason for Delbegetei massif formation. [ABSTRACT FROM AUTHOR]

Deciphering magmatic-hydrothermal evolution and rare metal mineralization mechanisms in granitic systems is always challenging, particularly when elucidating the intricate details of magmatic-hydrothermal transition, the critical stage when the system changes from melt-driven to fluid-driven with associated metal extraction. Here we present a case study of the Huoshibulake Nb-REE-mineralized alkali pluton in the north margin of the Tarim Carton, China. The pluton exhibits abundant tourmaline-quartz orbicules and tourmaline-quartz veins, which are the products of immiscible B-rich melt exsolved during the magmatic-hydrothermal transition. Three types of zircon crystals with different morphology have been recognized in the pluton: antecrystic, autocrystic and hydrothermal zircons, the latter two representing the melt and fluid parts of the system. LA-ICP-MS U Pb dating of autocrystic zircon from granite and orbicule samples (206Pb/238U ages of 274.8 ± 1.5 and 273.6 ± 2.0 Ma, respectively) and cassiterite from the vein sample (lower 206Pb/238U intercept age of 271.4 ± 4.1 Ma) overlap within error. The similar trace-element patterns and near-identical O-isotopic compositions between hydrothermal and autocrystic zircons indicate that the hydrothermal zircons were crystallized from magmatic fluids. Zircon Hf O isotopic systematics suggests that the coeval A1-type granites in the Halajun area evolved from a single parental magma chamber which originated from ∼30% of the upper crustal material mixed with ∼70% mantle-derived mafic magma. Whole-rock compositional trends reveal that fractional crystallization of felsic minerals contributed to the rare metal enrichment. The rare metal mineralization in the veins and the close association of rare metal mineralization with fluorite indicate the critical role of F-rich hydrosilicate liquids in rare metal mineralization, which is also recorded by the significant increase of rare metal concentrations from the autocrystic to the hydrothermal zircon grains. • Polygenetic zircons occur in the Huoshibulake A1-type rare metal granite. • Tourmaline-quartz orbicule and vein record the exsolution of B-F-rich aqueous melt. • F-rich hydrosilicate liquid is a key medium for the rare metal mineralization. [ABSTRACT FROM AUTHOR]

The continents across Earth have grown through accretion and amalgamation of plume-generated oceanic plateaux and subduction-originated magmatic arcs. The evidence of such evolutionary processes is well preserved in the greenstone belts of Canada, South Africa, China, Australia and India. Unlike accretion that leads to lateral growth of the continents, flood basalt volcanism results in the superposition of large volumes of dense mafic material above relatively less dense sialic upper continental crust. The resulting density inversion is liable to generate tectonic stresses resulting in faulting of under burden along weak planes. The nature of the crust obscured beneath flood basalt provinces that have accumulated over the past 500 My in Large Igneous Provinces (LIPs) has remained enigmatic, largely because of the voluminous lava pile that deters access to the concealed basement, unless otherwise retrieved through deep continental drilling. Here, we present in situ zircon U Pb geochronology and bulk-rock geochemistry of a volcanic sequence discovered at −400 m m.s.l in the deep bore-hole well-core KBH-5 of the southwestern Deccan Traps, India. The ∼300 m thick metavolcanic succession includes a basalt – Nb-enriched basalt – andesite – Mg-andesite – dacite – adakite suite. The zircons yielded a 2.58 Ga U-Pb age for the suite, which also incorporates entrained zircon xenocrysts of 2.7 Ga age from a preexisting juvenile material during its emplacement. The bore-hole KBH-5 is located on an NNW-SSE trending normal fault, paralleling a series of major faults west of the Western Ghat Escarpment. Although the crustal block plummeted ∼1000 m downward along the fault plane, the geochemical attributes of the metavolcanic rocks are thoroughly comparable to those reported in the Medur Formation of the Shimoga greenstone belt, ∼300 km south of KBH-5 in the western Dharwar craton. Our study provides the first physical evidence of Dharwar greenstone belt(s) extending further beneath the Deccan Traps, which was previously only speculative based on short-wavelength gravity highs. The metavolcanic sequence evolved in a subduction-related back-arc tectonic regime and accreted to the active continental margin of India in the Neoarchean. Unveiling of potentially similar scenarios in cratons elsewhere entrapped beneath the vast canopy of continental flood basalts, would reveal new crustal growth events during the Archean -Proterozoic transition across the Earth. • We report the discovery of Neoarchean arc-volcanics beneath the Deccan Traps. • Basalt – Nb-enriched basalt – Mg-andesite – Adakite – Dacite suite of rocks. • 2.58 Ga contributes to peak of crustal growth activity in the Dharwar Craton. • Shimoga greenstone belt extends ∼300 km further north beneath the Deccan Traps. • It is a subduction accreted orogen at the paleo active continental margin of India. [ABSTRACT FROM AUTHOR]

The Venda Nova and Várzea Alegre Plutons in southeastern Brazil are post-collisional complexes formed during the gravitational collapse of the Araçuaí-Ribeira orogenic system during amalgamation of SW Gondwana. This study focuses on the petrological, geochemical, geochronological and zircon Lu-Hf isotopic signatures of both plutons to constrain and complete their ages and to characterize mantle vs. crustal source components. The Venda Nova Pluton is divided into an inner, mildly alkaline, and an outer, calc-alkaline domain. One diorite, three quartz syenites and two granites from the inner domain give LA-ICP-MS zircon U-Pb ages of 492–477 ± 8 Ma. The outer domain is dominated by charnockites and norites, six measured charnockites give two zircon ages of 620–606 ± 11 Ma and 500–476 ± 14 Ma, corresponding to zircon core and rim, respectively; the only norite yielding zircons gives a nominal age of 567 ± 13 Ma, which cannot be simply interpreted as emplacement age. The various intrusives from the Várzea Alegre Pluton (gabbronorites, charnockites, monzogranites, syenogranites) straddle the alkaline to calc-alkaline affinity and yield all together a uniform age of 500 ± 8 Ma. This confirms that all lithologies from the Venda Nova inner domain and Várzea Alegre Pluton belong to the post-collisional G5 suite of this region. The Venda Nova outer domain charnockites, fit age-wise into the pre-collisional arc-related magmatism (G1 suite). The zircon rim ages obtained on these charnockites represent minor fluid-assisted partial remelting and resetting of the U-Pb system during the emplacement of the inner domain. Individual norite zircons show ages ranging from the charnockite intrusion age to the metamorphic thermal peak in this region. The Lu-Hf isotopes measured on the dated zircon crystals, yield mantle values for the charnockites from the Venda Nova outer domain (εHf: 3.4 ± 1.2 to 6.8 ± 1.5), indicating an isotopically depleted mantle source, consistent with arc magmatism. Instead, the Venda Nova inner domain and the Várzea Alegre Pluton have relatively radiogenic values (εHf: −12.3 ± 1.5 to −8.8 ± 2.9 and − 11.1 ± 1.1 to −7.4 ± 1.3, respectively) and show no significant variation between all lithologies, indicating a source dominated by a previously crustally enriched mantle with only minor crustal assimilation occurring during magma emplacement. Interestingly, the charnockite rim of Venda Nova is 100 Ma older than the inner (mildly alkaline) post-orogenic domain and belongs to the pre-orogenic calc-alkaline arc suite, while the charnockite ring at Várzea Alegre is part of the intrusion, both in time and geochemistry, and shows no increased crustal signature with respect to the rest of the pluton. • Age and magmatic source constrain of Venda Nova and Várzea Alegre Pluton. • Venda Nova inner domain + entire Várzea Alegre are post-orogenic (G5, ∼500 Ma). • G5-suite melts derive from a previously crustal enriched lithospheric mantle. • Venda Nova calc-alkaline charnockite rim (G1, ∼610 Ma) derived from depleted mantle. • Constant εHf with differentiation suggests minor crustal assimilation. [ABSTRACT FROM AUTHOR]

South China block contains abundant rare metal resources that have widely been considered to be associated with highly evolved granitic magmatism and related fluid metasomatism. Here we perform detailed geochemical analyses on apatite and bulk rock from the ore-bearing granites (equigranular zinnwaldite granite) and ore-barren granites (porphyritic biotite granite and granitic dyke) at Qianlishan pluton, South China, to decipher the respective roles of magmatic and fluid processes and further understand the petrogenesis of rare metal granite (RMG). Apatites from both granite types are F-rich, displaying heterogeneous textures and large compositional variations in Cl, Sr, rare earth elements (REEs), Ga, Th, and U. Relative to the ore-barren granite, the apatites from ore-bearing granite contain lower Sr but higher ∑REE, Th + U and Ga, reflecting more evolved features. The oscillatory compositional zonation and bimodal O-Nd isotopic compositions in apatite from the ore-barren granite indicate multiple-pulse intrusion instead of other open-system processes such as magma mixing and/or crustal assimilation during magmatic evolution, while the additional occurrence of monazite and lower δ18O (< 8‰) in half of the apatite crystals from the ore-bearing granite require further influence of hydrothermal metasomatism. In combination with their high W + Sn concentrations and La tetrad effect in chondrite-normalized REE patterns, the ore-bearing granite experienced extensive metasomatism, during which the fluids in equilibrium with the metasomatic apatite were likely magmatic in origin. We therefore suggest that multiple-pulse magmatic intrusion and fluid metasomatism are two predominant factors during the formation of highly evolved RMG, such as the Qianlishan pluton in South China. Our results demonstrates that apatite geochemistry can be a potential approach to monitoring the magmatic evolution and fluid metasomatism during rare metal mineralization. • Qianlishan pluton shows large elemental and isotopic variations in apatite. • Multiple-pulse magmatic intrusion is a key to highly evolved rare metal granite. • Fluid metasomatism promotes the rare metal enrichment and mineralization. [ABSTRACT FROM AUTHOR]

In the eastern and central Anti-Atlas of Morocco, the Late Neoproterozoic Ouarzazate Group (OG) forms a ∼ 2 km-thick section of volcano-sedimentary rocks deposited during intermittent magmatic activity, spanning a time period between 590 and 540 Ma. In the eastern Anti-Atlas, the stratigraphy of the OG, termed IMS (Imiter Mine succession), includes four units that reflect a gradual change from fluvial to lacustrine depositional sedimentary environments. In the central Anti-Atlas, the deposition of the OG occurs within a caldera environment, consisting of five units referred to as BMS (Bou Azzer Mine succession). U Pb dating on zircon from the rhyolite lava flow at the top of the IMS constrains the latest lava flow of the IMS to 570.7 ± 2.1 Ma. In the Bou Azzer inlier, the stratigraphically correlated basal andesite and top dacite lava flows were emplaced at 590.6 ± 4.2 Ma and 555.9 ± 20.4 Ma, respectively, suggesting that the OG was constructed through successive pulses within a long-lived magmatic episode. The magmatic rocks display geochemical signatures typical of continental arc magmas, including high-K calc-alkaline to shoshonite composition, enrichment in LILE, and negative Nb, Sr, Ti and P anomalies. Nd isotopes indicate that magmas supplying the plumbing systems of the IMS and BMS constitute transitional products resulting from a combination of orogenic and intraplate volcanism, involving deep crustal recycling. The compositions of these magmas evolved through processes of crustal contamination, bulk assimilation, and minor fractional crystallization of the parent melt. High εNd values of the BMS rocks argue for a juvenile origin, whereas lower εNdt recorded in the IMS likely reflect old crustal protoliths and an overall less contribution of juvenile material in their source. The magmatic rocks of the OG are interpreted as products of a large igneous province (LIP) developed by a post-collisional delamination model that initiated tens of millions of years after the subduction-collision process stage of the Pan-African orogeny in the northwestern part of the West African Craton (WAC). [Display omitted] • The volcano-sedimentary rocks of the OG comprise a ∼ 2 km-thick pile, deposited between 590 and 540 Ma. • The process of delamination is responsible for the formation of this post-collisional magmatism. • The εNd values suggest their overall juvenile origin, and varying degrees of contamination. • These volcanics are related to a Late Neoproterozoic LIP in the Northwestern part of the WAC. [ABSTRACT FROM AUTHOR]

Most tin deposits in the world are genetically related to tin granite and form during complex magmatic-hydrothermal processes. Zircon is a common accessory mineral in granite and related ore systems and can host a number of ore metals, such as Sn, W, Nb, Ta, U and Th, in its crystal lattice. However, whether metal enrichment/depletion can trace ore-forming processes is still unclear. Here, we report that the metal concentrations in various types of zircons from the Mopanshan tin granites in the southern Great Xing'an Range (Northern China) can be used as good indicators of fluid metasomatism and Sn mineralization. Two lithological zones are developed in the Mopanshan pluton, including porphyritic syenogranite (PG) in the center and fine-grained syenogranite (FG) at the margin. Zircons in the PG (PGZ-1, PGZ-2, and PGZ-3) are all magmatic in origin, while zircons in the FG can be categorized into magmatic zircons (FGZ-1 and FGZ-2) and metasomatic zircons (FGZ-3). The PGZ-1 and FGZ-1 grains are transparent prismatic crystals with bright oscillatory zonation, whereas the PGZ-2 grains are murky crystals with dark oscillatory zonation. PGZ-3 and FGZ-2 grains occur as overgrowths of previously formed zircon (PGZ-1, PGZ-2, and FGZ-1) or as brown individual crystals, showing dark and homogeneous cathodoluminescence (CL) textures. The metasomatic FGZ-3 grains are translucent-opaque porous crystals with vermicular CL zonation and commonly replace FGZ-2. The trace element compositions of magmatic zircons are completely melt controlled, providing a record of magmatic evolution as a constant decrease in Zr/Hf ratios and a gradual increase in Th, U, Nb, and Ta contents. Moreover, the structure of magmatic zircons transforms from a crystalline state to an amorphous state as a consequence of radioactive decay of U and Th. A coupled dissolution-reprecipitation process is proposed for the formation of metasomatic FGZ-3. The reactive fluid is the magmatic fluid that exsolved from the melt in the late magmatic stage. The magmatic fluid replaced biotite and rare earth phosphates (mainly monazite and apatite) enclosed within biotite, resulting in significant amounts of Nb, Ta, Sn, P, Al, Ca, Fe, and REEs, which subsequently reacted with the FGZ-2 zircons to leach Th, U, Y, and HREEs. Eventually, REEs, Y, Th, and U in the fluid combined with P to form monazite and xenotime, while the other elements partially precipitated with the crystallization of the FGZ-3 zircons. Although the alteration of biotite only released approximately 190 ppm of Sn into the fluid, this is still a significant Sn source for the Sn deposits surrounding the Mopanshan pluton, taking the granite size (∼50 km2) and the volume proportion of biotite (∼5%) into account. Furthermore, based on previous studies on tourmaline from the Mopanshan granite and regional geochemistry, it may be inferred that the addition of wall rock components may also play an important role in Sn mineralization. [Display omitted] • Magmatic and metasomatic zircons have been identified in the Mopanshan granite. • Formation of metasomatic zircon is due to a dissolution-reprecipitation process. • Zircon records the enrichment of Sn during magmatic-hydrothermal process. • The release of Sn by biotite alteration is a significant Sn source for Sn deposits. [ABSTRACT FROM AUTHOR]

The Bashisuogong alkaline igneous intrusion is located between the South Tianshan Orogenic Belt and the Kepingtage foreland thrust belt at the northern margin of the Tarim Craton and hosts economically significant Nb–Ta–Zr–rare earth element mineralization. Eudialyte has recently been discovered in the syenite unit of this intrusion, which is the primary host mineral for high-field-strength and rare earth elements. Based on detailed petrographic investigations, this study investigated the behavior of trace elements during magma evolution and the enrichment of ore-forming elements using whole-rock geochemical analyses of eudialyte-bearing syenite and compositional analyses of aegirine–augite and different types of eudialyte. We also undertook in situ titanite U-Pb dating. The Bashisuogong syenite comprises aegirine–augite and aegirine–augite–eudialyte syenite, the latter of which have higher total rare earth element contents. Both types of syenite exhibit slight enrichments in light rare earth elements, significant enrichments in high-field-strength elements (Nb, Ta, Zr, Hf, and Th), depletions in large-ion lithophile elements (Ba and Sr), and large negative Eu anomalies. There are two types (I and II) of eudialyte. Eudialyte I has higher Mn/Fe, Zr/Hf, and Nb/Ta ratios but lower Th/U ratios compared with eudialyte II but similar Y/Ho ratios. Eudialyte II crystallized earlier than eudialyte I, and aegirine–augite, titanite, and apatite crystallized earlier than eudialyte I. Both aegirine–augite and eudialyte have similar trace element characteristics to the host rocks, exhibiting enrichments in highly incompatible high-field-strength and rare earth elements, as well as marked negative Eu anomalies and depletions in Sr. These characteristics suggest that the Bashisuogong alkaline rocks formed by low-degree partial melting of geochemically enriched, metasomatized lithospheric mantle, which formed an alkaline basaltic parental melt that then underwent protracted magma evolution and fractionation in the shallow crust. The eudialyte syenite yield a titanite U-Pb age of 277.3 ± 1.2 Ma, which is consistent with the ages of different types of alkaline igneous rocks in the study area, indicating they were the products of the same magmatic event. Temporally and spatially, the Bashisuogong ore-bearing alkaline rocks were associated with the Tarim mantle plume, and the mantle plume provided the heat for their formation. [Display omitted] • Eudialyte-bearing syenite unit was discovered in the Bashisuogong alkaline complex. • Variation Zr/Hf, Nb/Ta, Th/U of Eud I and II are due to fractional crystallization. • Eudialyte geochemistry suggests syenite derives from alkali basaltic parent melt. • Titanite U-Pb dating reveals that eudialyte syenite is emplaced at ca. 277 Ma. [ABSTRACT FROM AUTHOR]

The consumption of the Palaeo-Asian Ocean domain triggered substantial resources and environmental effects, but the final suture timing remains debated. This study presents the zircon U-Pb age and Hf-O isotope, whole–rock element and Sr–Nd–Pb isotope data from the Elitu Formation trachyandesite and rhyolitic tuff in the Bainaimiao arc belt. The zircon U-Pb ages (260–280 Ma) indicate that the Elitu Formation volcanism erupted at the Kungurian to Capitanian. Trachyandesites exhibit an arc-like whole–rock trace element composition and have enriched Sr–Nd–Pb isotopic composition (I Sr (t) = 0.7062–0.7065; ε Nd (t) = −8.8 to −9.4; (206Pb/204Pb) t = 17.14–17.31) and high zircon δ18O (6.08‰–7.59‰) values, which are derived from the partial melting of the lithosphere mantle metasomatised by ancient sediment-derived melts. Rhyolitic tuffs have variable ε Hf (t) (−7.15 to +10.47) and low δ18O (4.99‰–6.21‰) values and exhibit affinities with I-type felsic rocks. They mainly originate from the partial melting of the basement of the Bainaimiao arc belt. Our compiled geochemical and geochronological data indicate that there were significant differences between the Early to Middle Permian Elitu Formation volcanic rocks and intrusive counterparts and the Early to Middle Triassic magmatic rocks from the Bainaimiao arc belt, and the Late Permian was the key tectonic transition period. The Late Permian transition was compatible with the regional crustal-shortening deformation, greenschist facies metamorphism and shift of deposition environment. This study argues that the Elitu Formation volcanism should be subduction-related and predate the final suture of the Palaeo-Asian Ocean domain at the Changhsingian. The suture of the Palaeo-Asian Ocean domain was not the original trigger of the Kungurian climate change in the North China Craton. [Display omitted] • The Elitu Formation volcanism erupted at the Early to Middle Permian. • The Early to Middle Permian volcanism is subduction-related. • The suture of the Palaeo-Asian Ocean domain was in the Late Permian. [ABSTRACT FROM AUTHOR]

The 595–560 Ma post-collisional magmatism in the Alto Pajeú Domain, Borborema Province, northeastern Brazil, is characterized by the intrusion of voluminous high-K calc-alkaline, shoshonitic and ultrapotassic magmas. The nature of the source rocks and the geodynamic context associated with the generation and emplacement of this post-collisional magmatism is still enigmatic. In this study, we report new U Pb ages, elemental geochemistry, mineral chemistry and Sr Nd isotope data for rocks from the Pajeú batholith. LA-ICP-MS zircon U Pb dating revealed that this batholith was formed by at least two distinct magma pulses. The oldest pulse (ca. 592 Ma) consists mainly of porphyritic quartz monzonites to monzogranites with abundant mafic microgranular enclaves (MMEs), while the younger pulse (ca. 568 Ma) is composed of equigranular biotite granites. The porphyritic monzogranites are magnesian, have intermediate to acidic compositions (SiO 2 = 62.2–67.6 wt%) and high Mg# (44–55) values. In contrast, biotite granites are ferroan, have high SiO 2 (69.3–73.1 wt%) and low Mg# (16–36) values. Both rock types are characterized by enrichment in LREE and LILE and depletion in HREE and HFSE, but with more fractionated REE patterns for biotite granites ([La/Yb] N = 67.4–101.5) than for porphyritic rocks ([La/Yb] N = 35.8–54.8). The Sr Nd isotopic values for the different rock types are roughly similar. However, biotite granites show slightly higher initial 87Sr/86Sr (0.71265–0.71412) ratios and more negative ε Nd (t) (−18.45 to −18.67) values than porphyritic monzogranites (initial 87Sr/86Sr ratios from 0.71077 to 0.71155 and ε Nd (t) from −16.04 to −16.96). These geochemical and isotopic signatures, together with mineral chemistry data, suggest different sources for the two rock types. The biotite granites are of purely crustal origin, derived by partial melting of a Paleoproterozoic amphibolitic lower continental crust, while a mixture of melts derived from the Paleoproterozoic continental crust and magmas derived from an enriched lithospheric mantle could explain the origin of porphyritic monzogranites. Based on the spatial and temporal distribution of magmatic rocks from the Alto Pajeú Domain, we suggest that a local lithospheric thinning model could explain the evolution of post-collisional magmatism in this region of the Borborema Province. • Several sources were involved in the generation of the Pajeú batholith granitoids. • Heterogeneous continental crust is most likely the source of the ferroan granitoids. • Domains of the lithospheric mantle were metasomatized rather than the entire mantle. • Post-collisional magmatism in the APD was triggered by a lithospheric thinning event. [ABSTRACT FROM AUTHOR]

The tectonic transition from oceanic subduction to continental collision is a fundamental process during orogenesis. Yet, the nature of this transition and its deep geodynamic processes for the southern Tibetan Plateau remain contentious. This study presents zircon U-Pb-Hf isotopes, whole-rock geochemistry, and Sr Nd isotopes for a quartz diorite intrusion and bimodal dykes from Dagze, combined with compiled data from the southern Lhasa subterrane, to reveal the geodynamic processes of late-stage of Neo-Tethyan subduction. Most of Dagze samples were emplaced between 66 and 64 Ma, while muscovite granite aplite dykes were emplaced between 64 and 60 Ma. They exhibit relatively uniform, depleted Sr Nd isotopes, with ε Nd (t) values ranging from +2.2 to +4.0, positive zircon ε Hf (t) values, and young depleted mantle model ages. Both exhibit compositional characteristics of subduction-related arc magma, marked by the enrichment of large ion lithophile elements and the depletion of high field strength elements. The mafic dykes with relatively low SiO 2 , high MgO, Cr, Ni, possibly originated from a fluid-metasomatized depleted mantle. The quartz diorite intrusion with low MgO, Cr, and Ni was generated by partial melting of sub-arc lithospheric mantle and experienced subsequent fractional crystallization of amphibole, clinopyroxene and orthopyroxene. The granitic dykes originated from partial melting of Gangdese juvenile crust and experienced fractional crystallization dominated by plagioclase. We suggest that the slab rollback and continental collision conjointly controlled the evolution of the latest Cretaceous to Paleocene Himalayan–Tibetan orogeny. Slab rollback of Neo-Tethys commenced around 70 Ma, triggering the partial melting of depleted mantle and juvenile crust, and this process resulted in the formation of Dagze diorites and bimodal dykes with arc affinity. • Diorite intrusion and mafic dykes originated from a fluid-metasomatized depleted mantle. • Granitic dykes originated from Gangdese juvenile crust and experienced fractional crystallization. • Slab rollback of the Neo-Tethys oceanic slab commenced around 70 Ma. [ABSTRACT FROM AUTHOR]

The Corno Alto complex represents the onset of the intrusive igneous activity during the Alpine Orogen and for this reason has particular importance in the interpretation of the geodynamic evolution of the Alps. Whole-rock chemistry of the granitoid rocks of the Corno Alto complex reveals peculiar features with respect to the other units of the Adamello batholith, and to typical I-type and S-type granitoids. In particular, the Corno Alto rocks are enriched in Ba, Sr and La/Yb at any given SiO 2 content. U Pb geochronology on zircon suggests an incremental assembly of the Corno Alto complex by multiple and possibly discrete magma injections in a time span of about 5 Myr starting from 44 Ma. The different zircon domains have significantly distinct Hf isotopic signature (up to 18 ɛHf units of variation) with some values trending towards the isotopic composition of the depleted mantle (DM). Bulk major and trace element geochemistry together with in-situ Hf isotope composition of zircon allow to distinguish at least two geochemically components in the Corno Alto rocks: i) a high Ba component characterized by high Sr and La/Yb ratios, likely derived from melting of carbonate sediments of slab origin; ii) a juvenile component with Hf isotopic signature close to the DM and capable to crystallize plagioclase with An 90 , which is interpreted as the primitive mantle signal. This work constrains for the first time the occurrence of a slab derived carbonate input in the mantle-derived melts during the onset of the Alpine magmatism (dated at 44 Ma). The anomalously high thermal conditions required to induced carbonate melting may reflect the rise of asthenospheric material near the torn edge of the European slab where the Corno alto is located. Remarkably, these high thermal conditions parallel those at the Archean-Proterozoic transition and the Corno Alto complex could thus represent a kind of modern analogues of the high Ba/K sanukitoids. • The Corno Alto complex consists of three types of granitoid rocks. • The Corno Alto complex is chemically peculiar in the Adamello framework. • High Ba content likely derived from melting of carbonate sediments of slab origin. • The Corno Alto complex is a modern analogue of the high Ba/K sanukitoids. [ABSTRACT FROM AUTHOR]

Geochemical and isotopic markers of the most primitive basaltic melts allow us to understand the temporal evolution of the lithospheric mantle and geodynamic processes. This paper presents the geochemical, Sr-Nd-Pb-Hf isotopic data, K Ar dating and the petrological evolution of the petrogenesis of the late Miocene-early Pliocene basaltic volcanism observed in the Baltacık-Günkoru region in the northeastern of Lake Van in Eastern Anatolia Collision Zone (EACZ). These data allow us to understand the origin of collision-related magmatism and the geodynamic processes in the late Miocene-early Pliocene in the EACZ. Geochronological age data (K Ar) indicate that basaltic volcanism erupted between ∼7.63 and 5.24 Ma. Major-incompatible trace element contents, Sr Nd isotopic compositions of the studied samples and EC-AFC (energy-constrained recharge, assimilation, and fractional crystallization), and MELTS model calculations point out that basaltic volcanism has undergone fractional crystallization but unaffected crustal contamination. Petrological models created using 87Sr/86Sr, ℇNd and ℇHf isotopic data, together with calculated primary melt compositions of basaltic lavas, indicate that the DMM-type (Depleted Morb Mantle) mantle source is metasomatized by melts rather than fluids derived from subducted oceanic lithosphere. Combined trace element and isotopic modelling results indicate that the calculated primary melts were formed by 2.5–5% melting of a metasomatised spinel-garnet lherzolitic mantle source, including amphibole and 1% residual rutile. This mantle source has been metasomatised by a 1–3% contribution of subducted slab component, with a sediment melt/AOC (altered oceanic crust) melt ratio of about 90:10. Thermobarometric calculations based on calculated primary melts compositions indicate that the lithosphere-asthenosphere boundary (LAB) is a depth of 67 ± 4 km for 7.53–5.24 Ma. Literature data and the findings obtained from this study indicate that the late Miocene to early Pliocene basaltic volcanism in the south of the EACZ) is progressed by the delamination of the mantle lithosphere. This delamination occurred in a fragmented/patched or dripping manner rather than whole-scale delamination in the 3–4 million years between ∼9 Ma and 5–6 Ma. [Display omitted] • Studied basalts erupted in the Late Miocene to Early Pliocene. • LAB under EACZ decreased from Late Miocene to Early Pliocene via delamination. • Delamination emerged fragmented/patched or dripping rather than a whole scale. [ABSTRACT FROM AUTHOR]

The Gréixer Rhyolitic Complex is one of the most important manifestations of the post-Variscan Permo-Carboniferous volcanism of the Catalan Pyrenees. This volcanic complex is represented by a > 800 m thick, > 12 km wide, intra-caldera succession, mostly composed of strongly-welded, lava-like rheomorphic rhyolitic pyroclastic rocks. Previous studies have attributed a Lower Permian age to this caldera complex and interpreted it as having resulted from the gravitational collapse of a central volcanic edifice after a large-volume explosive event, mostly represented by widespread extra-caldera pyroclastic deposits (the Castellar de n'Hug Ignimbritic Member), which was radially emplaced from the caldera structure. However, new stratigraphic, structural, geochemical, and geochronological data reveal that this co-genetic relationship between the inferred intra- and extra-caldera deposits does not exist. On the contrary, each of these two successions of pyroclastic deposits resulted from a different volcanic event, which had occurred within a time span of 15 Ma. Moreover, the geochemical signature of these volcanic rocks shows a different magma source for each case, with a clear crustal origin for the Gréixer Rhyolitic Complex and a mixed mantle-crustal origin for the Castellar de n'Hug Ignimbrite Member. The apparent stratigraphic correlation between both successions is the result of the Alpine tectonics, which put together different late and post-Variscan Permo-Carboniferous rocks that had originated in different areas and at different times. • The Gréixer Rhyolitic Complex is distinctive geological element of the Pyrenees. • It corresponds to a rheomorphic rhyolitic pyroclastic rocks intra-caldera succession. • U-Th dating gave a Stephanian C age (303 Ma years, Gzhelian) for these rhyolitic rocks. • The Gréixer Rhyolitic Complex has a clear crustal signature. [ABSTRACT FROM AUTHOR]

Herein, we analyze the elemental composition and Sr–Nd–Pb isotopic data of the gabbroic rocks (gabbros and gabbroic diorites) from the forearc of the Yap trench in the western Pacific to investigate the early arc magmatism. The gabbroic diorites, which exhibit a negative Eu anomaly and relatively flat REE patterns with slight LREE depletion, represent the evolved magma that has undergone varying degrees of fractional crystallization. In contrast, the gabbros, which exhibit a positive Eu anomaly and a significant depletion of LREE, can be further classified into two groups. The noncumulate Group 1 gabbros have composition closely resembles that of gabbroic diorites and the Group 2 gabbros represents cumulate rocks formed through melt crystallization. Most of the studied gabbroic rocks exhibit negative anomalies in high-field-strength elements, such as Nb, Zr, Hf, and Ti, accompanied by very low Ti/V and Nb/Yb ratios. Based on these features, they are suggested to originate from the partial melting of a depleted forearc mantle, which is supported by their high 143Nd/144Nd ratios that are similar to those of forearc basalts (FAB). The forearc origin of gabbroic rocks is further supported by their plagioclase composition, which exhibits a higher anorthite content (An: 86–99) compared to the plagioclase in backarc and mid-ocean ridge gabbros when coexisting with identical clinopyroxene composition. However, even though the major- and trace-element compositions of the Yap gabbroic rocks are similar to those of FAB, their large-ion lithophile element content (e.g., Cs, Rb, Ba, and Th) and 87Sr/86Sr ratios considerably exceed the values of FABs, highlighting their similarity to boninites. In addition, their Ba/Yb and Th/Yb ratios are higher than the mid-ocean ridge basalt values and plot between the FAB and boninite fields in Ba/Yb versus Th/Yb diagram. Consequently, we propose that the Yap gabbroic rocks evolved from an early arc magma, which was produced by a combination of decompression melting and fluid-flux melting. Thus, they exhibit a transitional composition that falls between FABs and boninites. The exposure of intrusive rocks related to the early arc magmatism in the Yap forearc is a consequence of the extensive tectonic erosion induced by the collision of the Caroline ridge with the trench. This collision resulted in the erosion of the volcanic crust, exposing the underlying plutonic rocks. Therefore, intrusive rocks likely hold a preserved record of the early arc magmatism in subduction zones exhibiting extensive tectonic erosion. The Yap arc system is characterized by multiple episodes of magmatism, and the collision with the Caroline ridge may prevent the Yap arc magmas from evolving into mature arc magmas. • Gabbros and gabbroic diorites from the forearc of the Yap trench are investigated. • The gabbroic rocks exhibit characteristics resembling those of FABs and boninites. • The gabbroic rocks evolved from the early arc magma of the Yap arc system. • Information on early arc magmatism is preserved within the forearc intrusive rocks. [ABSTRACT FROM AUTHOR]

The volcanism of the Arasbaran region, northwest Iran, is characterized by multiple magmatic pulses from Cretaceous to Quaternary related to the consumption of the Neotethys oceanic basin and the subsequent continental collision between the Arabia and the Eurasian plates. In this paper we focus on the Eocene igneous products, which show wide compositional variations, ranging from shoshonite to tephrite and phonolite. They may be further grouped into leucite (analcime)-bearing and leucite-free rock types on the basis of their rock-forming minerals. Leucite-bearing and leucite-free Eocene magmatic rocks are geographically separate outcropping in the WNW and ESE part of the Ahar-Arasbaran region, respectively. K Ar dating show leucite-bearing rocks (39.4–39.6 +/− 1.0 Ma) being slightly younger with respect to leucite-free rocks (41.0–41.9 +/− 1.0 Ma). The two rock types are differentiated by each other in terms of silica saturation degrees but display similar incompatible trace elements distributions, typical of subduction-related volcanic rocks. Indeed, clear depletions in HFSE (e.g., Nb, Ta, Ti, Zr) and enrichments in LILE (e.g., Ba, K) and Pb are shown. The leucite-bearing volcanic rocks are strongly silica-undersaturated (Δq ca. -35) and show higher LILE/HFSE, LILE/REE, Ba/La (30–90) and Ba/Th (up to 520) values with respect to leucite-free rocks (Δ q from 0 to −15; Ba/La up to 30). Leucite-bearing and -free groups also show distinct Sr-Nd-Pb isotopic compositions, with the former having less radiogenic Sr (87Sr/86Sr 0.704424–0.704634) and Pb (206Pb/204Pb 18.58–18.65, 207Pb/204Pb 15.57–15.60, 208Pb/204Pb 38.63–38.71) and more radiogenic Nd (143Nd/144Nd 0.512695–0.512791), with respect to the latter ones (87Sr/86Sr 0.704481–0.705669, 206Pb/204Pb 18.65–18.75, 207Pb/204Pb 15.61–15.64, 208Pb/204Pb 38.65–38.87, 143Nd/144Nd 0.512572–0.512623). Geochemical and isotopic compositions, coupled with the strong silica-undersaturated character, of leucite-bearingrocks suggest in their mantle source the involvement of metasomatizing partial melts from subducted altered oceanic crust and subordinate carbonate-bearing sediments. On the other hand, the compositions of leucite-free igneous rocks are compatible with the involvement of a relatively higher contribution of partial melts from terrigenous (carbonate-poor) subducted sediments. The close spatial association and the relative geographical/stratigraphic position of these products indicate diachronous metasomatic events in the mantle wedge underlying the Arasbaran area that could have been originated by the late arrival of carbonate-rich sediments at depth during slab steepening and incipient roll-back preceding the continental collision. K Ar dating indicates that the Arasbaran magmatism was triggered by a late geodynamic event, during middle Eocene, plausibly consisting of re-adjusting of isotherms that heated the veined mantle wedge following the slab migration after roll-back. The slightly younger age of leucite-bearing rocks with respect to leucite-free rocks, coupled with the lower melting degree of the former may suggest an evolution of the local thermal regime with the progressive involvement of portions of the mantle wedge closer to the subducted plate. • A subduction-related magmatic pulse occurred in NW Iran at ca. 40 Ma. • Shoshonite leucite-free slightly preceded UK leucite-bearing volcanism. • Leucite-free magma source was metasomatised by dominant LC-sediment melts. • Leucite-bearing magmas was metasomatised by dominant HC-sediment melts. • Leucite-bearing rocks share similarities with Neapolitan Roman-type UK rocks. [ABSTRACT FROM AUTHOR]

How to reconstruct the detailed processes and identify the key factors of incremental growth to form a large granite batholith is controversial. Such in-depth investigations along convergent plate boundaries are of great importance for better understanding the growth and reworking of continental crust. This work presents an integrated study of SIMS (secondary ion microscope) U-Pb geochronology, trace elements and oxygen isotopes of zircon, microstructure and chemistry of plagioclase, and whole-rock elemental geochemistry and Sr-Nd isotopes to decipher the temporal compositional change and incremental growth of the Quxu granitoid batholith in the Gangdese magmatic belt, southern Tibet. The Quxu host granitoids are mainly metaluminous and calc-alkaline to high-K calc-alkaline in geochemistry, whilst the melanocratic microgranular enclaves (MMEs) and mafic dykes vary from calc-alkaline to shoshonitic series. New SIMS zircon U-Pb data suggest a prolonged history (ca. 16.6 Myr) for the Quxu batholith accompanied by several episodes of intermediate–mafic magma replenishments. Zircon δ18O and whole-rock (87Sr/86Sr) i values fluctuate from ∼5.6‰ to ∼6.8‰ and from 0.7038 to 0.7085, respectively, while the whole-rock ε Nd (t) values show a fluctuated decrease from +5.2 to −4.5 with time. The calculated Ti-in-zircon temperature (574–903 °C) and oxygen fugacity (ΔFMQ –0.9 to ΔFMQ +3.2) of the granitoid magmas fluctuated as well. The youngest group of the host granitoids is distinguished by the most elevated Th/La (>1.5) and Th/Ce (>1.0) ratios and K 2 O contents (>3.0 wt%) with evolved isotopic compositions, implying pronounced incorporation of supracrustal materials into the source region. Microstructural and compositional features of zircon and plagioclase from the host granitoids indicate that the incremental assembly of Quxu batholith was foremost facilitated by multiple episodes of magma recharge with distinct compositions and sources. The temporal variations of magma condition and composition throughout the lifetime of the magma reservoir highlight the importance of determining the longevity of batholiths and clarifying the discrepancy of individual magma pulses before deciphering the genesis of composite batholith. The aforementioned Sr–Nd–O isotopes show good correlations with the fluctuating whole-rock (La/Yb) N (2.7–68.5) and zircon Eu/Eu* (0.02–1.26) ratios, which further affirms episodic syn -collisional crustal thickening and episodic input of supracrustal material in magma sources. Based on the spatiotemporal variations of geochemistry, we propose a zoned incremental growth model to better illuminate the detailed processes of the incremental amalgamation of the Quxu batholith. [Display omitted] • An integrated study of zircon SIMS U-Pb age, trace elements and oxygen isotopes for Quxu batholith. • A long-lived (∼16.6 Myr) magma reservoir with episodic magma reactivation events. • A progressive involvement of supracrustal materials into the magma sources is observed. • We reconstruct a zoned incremental growth model for the Quxu batholith. [ABSTRACT FROM AUTHOR]

The Early Paleozoic tectonic architecture of East Kunlun Orogen in the northern Tibetan Plateau is crucial to deciphering the tectonic evolution of the Proto-Tethys ocean. The Wutumeiren ophiolitic mélange located in the Qimantagh-Xiangride suture between the North Qimantagh and Central Kunlun belts represents essential records of the Proto-Tethyan tectonic domain. It comprises serpentinite, dolerite, basalt and black chert with minor siltstone. The serpentinites possess high MgO, low SiO 2 and ΣREE contents, and are characterized by slight depletion of mid-REE, showing ophiolitic ultramafic affinities. Both dolerites and basalts exhibit tholeiitic compositions with high Mg# numbers, low (Na 2 O + K 2 O)/SiO 2 ratios and ΣREE contents. In comparison, the dolerites show flat patterns of REE, while the basalts display slight enrichment of LREE. All these features suggest they were generated from an E -MORB-type mantle source by different degrees of partial melting. The cherts exhibit distinctive high SiO 2 and low ΣREE contents, and show depletion of LREE with negative Ce anomalies and high Y/Ho rations, indicating they are typical abyssal cherts. Together with the comparable basements on both sides of the suture, a back-arc basin setting is suggested for these ophiolitic components. The SHRIMP zircon U–Pb age of 416 ± 34 Ma for the basalt, and the youngest age of 490.6 ± 6.6 Ma for the black siltstones interbedded with cherts signal the back-arc basin from ca. 490–416 Ma. We thus infer a west-Pacific-type active continental margin in the East Kunlun Orogen associated with the northward subduction of the Proto-Tethys oceanic crust in the Early Paleozoic. [Display omitted] • An Early Paleozoic ophiolitic mélange was identified in the East Kunlun Orogen. • Geochemical and geochronological investigation reveal a back-arc basin in 490–416 Ma. • Kunlun Orogen evolved in northward subduction with trench-arc-back arc basin tectonics. [ABSTRACT FROM AUTHOR]

Late Neoproterozoic Arbarastakh alkaline ultramafic carbonatite-phoscorite complex in the southern margin of the Siberian craton (Aldan-Stanovoy shield), includes carbonatites and phoscorites closely associated with pyroxenites-ijolites and ultramafic lamprophyres. Major and trace elements data, Sr, Nd and Pb isotope compositions for the Arbarastakh rocks have been obtained to characterize the sources involved in their formation, primary melt composition and to build the petrogenetic model. All rock varieties, excluding nepheline syenites, are characterized by incompatible elements enrichments, including light rare earth elements, and strong fractionation of REEs. The initial isotope ratios of the analyzed samples, calculated at 645 Ma, display limited variations: εNd from +5.9 to +6.9 and 87Sr/86Sr from 0.70225 to 0.70272, excluding nepheline syenite with εNd +5.4. The initial Pb isotope ratios for the most studied samples overlap with each other within uncertainties. They yield an age of 642 ± 5 Ma. The Nd and Sr isotope data of the Arbarastakh rocks generally fit the patterns of the other Neoproterozoic alkaline ultramafic carbonatite complexes of the southwestern and southern margins of the Siberian craton. Observed Sr, Nd and Pb isotope variations indicate mixing of the asthenosphere and the depleted mantle components. It is supposed that the primary melts for the Arbarastakh rocks were generated directly by low-degree melting of metasomatic phlogopite‑carbonate veins with apatite and Ti-oxides in garnet peridotite, which formed shortly before the onset of melting. Ultramafic lamprophyre (aillikite) is closest to the primary melt composition in terms of high #MgO, Cr and Ni. The aillikite and latter pyroxenite crystallized from primitive melt by fractionating the olivine, phlogopite and clinopyroxene dominated mineral assemblage that was free of feldspar. This fractionation forced Na-enrichment in the magmas resulted in liquid silicate‑carbonate immiscibility. Major and trace element and isotope data indicate that the nepheline syenites are unlikely to be related with other alkaline silicate rocks through fractional crystallization and could have been formed through pre-emplacement interaction with the ambient crustal materials. Emplacement of calcite carbonatites resulted in metasomatism of surrounding pyroxenites with formation of clinopyroxene-phlogopite-calcite carbonatites. Subsequent portions of Fe-P-enriched carbonatite magmas crystallized phoscorites and apatite-dolomitic carbonatites. • Isotope variations indicate mixing of the asthenosphere and the depleted mantle components • Ultramafic lamprophyre (aillikite) is closest to the primary melt composition • Crystallization fractionation forced Na-enrichment in the magmas • Emplacement of calcite carbonatites resulted in metasomatism of surrounding rocks [ABSTRACT FROM AUTHOR]

Volcanism in the Azores is generally accepted to result from the decompression melting in the upper mantle associated with the Azorean plume. Basalts on the island of São Miguel have been previously recognised as having δ18O values lower than MORB with different authors ascribing this low-δ18O signature to either a component within the plume itself or as the result of assimilation of crustal materials at shallow level. Here we assess these contrasting models by using a suite of samples that are both geographically and temporally spread. We find that while low-δ18O mafic magmas (reaching 4.98 ‰) do occur on São Miguel, they are spatially restricted to the Picos fissure system, between the central volcanoes of Sete Cidades and Fogo. Basalts of similar age from outside this restricted region return δ18O values that are similar to MORB. This spatial constraint argues that the source of the observed low-δ18O signature is within the crust rather than a component of the plume. Previous studies on mafic to intermediate rocks of the Picos fissure system have identified the assimilation of broadly syenitic lithologies, which were found as co-erupted lithic clasts at the Fogo volcano and may have δ18O values as low as 2.6 ‰. However, trace element geochemistry indicates that these lithologies have not been assimilated within our low-δ18O samples, a more likely assimilant is altered oceanic crust or mafic lavas within the island edifice. • Multi-mineral O isotopic study of basalts from the island of São Miguel • Some basalts have low-δ18O while the majority are MORB-like. • Low-δ18O magmas are primarily found within the Picos fissure system. • Similar aged basalts at Sete Cidades volcano c. 10 km W have normal-δ18O. • We suggest crustal assimilation causes the low-δ18O values of Picos basalts. [ABSTRACT FROM AUTHOR]

The Cave Peak deposit is a rift-related, breccia-hosted, fluorine-rich porphyry molybdenum deposit that is enriched in Nb, REE, and other critical minerals. Cave Peak is the easternmost member of a northwest-trending group of Paleogene intrusions in the Diablo Plateau along with the Marble Canyon stock, an unmineralized, petrogenetically related, compositionally zoned mafic alkaline pluton. The Cave Peak intrusions show within-plate geochemical affinity and is the product of a highly differentiated magma series. Curvilinear trends in Harker variation and trace element diagrams record magma differentiation from mafic to intermediate (44–69 wt% SiO 2) to felsic (70–76 wt% SiO 2) compositions at Marble Canyon and Cave Peak, respectively. Quartz syenite and monzonite from the Marble Canyon stock yielded zircon U Pb ages of 36.2 ± 0.15 Ma and 36.1 ± 0.09 Ma, respectively. The youngest major intrusion at Cave Peak, an alkali feldspar granite porphyry, has a zircon U Pb age of 34.8 ± 0.4 Ma, supporting that these intrusions represent a magma differentiation trend. The δ98Mo of Cave Peak molybdenites range between −0.39 ± 0.06 ‰ and + 0.52 ± 0.06 ‰ with a total Mo isotope range of 0.91 ‰. Cave Peak samples predominantly fractionated towards heavier δ98Mo. The Cave Peak data are distinctly heavier than data obtained from the nearby subduction-related Red Hills porphyry Cu deposit which has δ98Mo values of −0.25‰ to −0.51‰. • New U Pb zircon ages are acquired from Cave Peak and Marble Canyon. • A magma differentiation trend is observed from Marble Canyon to Cave Peak. • REE + Y concentrations are elevated for both in Cave Peak and Marble Canyon rocks. • A total δ98Mo variation of 0.91 ‰ is observed within the Cave Peak system. • Cave Peak molybdenites predominantly fractionated towards heavy δ98Mo. [ABSTRACT FROM AUTHOR]

As one of the Cordilleran-type metamorphic core complexes in the western Anatolian extensional province and the broader Aegean region, the Çataldağ metamorphic core complex is composed of a granite-gneiss-migmatite complex and a synkinematic pluton, bounded by a detachment fault zone. The plutonic rocks within the footwall of the Çataldağ metamorphic core complex consist of Eo-Oligocene anatectic S-type leucogranites associated with gneiss-migmatite complex forming the core rocks and an I-type synkinematic pluton that emplaced into the core rocks in the Early Miocene. This paper presents the petrography, mineral chemistry, major-trace element geochemistry, and Sr-Nd-Pb isotope compositions of the Çataldağ I-type synkinematic pluton. It discusses the magma source evolution from the Eo-Oligocene to the Early Miocene and their relations to the Çataldağ metamorphic core complex formation by comparing two contrasting granitic associations from a petrological perspective. The Çataldağ I-type synkinematic pluton primarily comprises porphyritic granodiorite, granite, and peripheral rocks including evolved granite and pegmatite dikes. Thermobarometry calculations estimate crystallisation conditions of approximately 795 °C at 1–2 kbar (averaging 1.5 kbar), corresponding to a shallow crustal magma chamber (⁓5 km deep). The pluton is metaluminous to slightly peraluminous and of a high-K calc-alkaline character. The 87Sr/86Sr (i) and εNd values of the studied samples range from 0.70684 to 0.70772 and from −6.1 to −2.3, respectively. Pb isotopic compositions are 18.74–19.29 for 206Pb/204Pb, 15.69–15.78 for 207Pb/204Pb, and 38.89–39.39 for 208Pb/204Pb. Geochemical modelling shows that a large amount of metasomatised lithospheric mantle-derived melt component (up to 70%) and a minor crustal component (<50%) contributed to the source region of the magma. The combination of isotopic data and thermodynamic modelling suggests that the compositional variations within the pluton were primarily the result of open system processes, predominantly the assimilation of crustal rocks with a dominance of fractional crystallisation. The Sr-Nd-Pb isotopic signatures and trace element characteristics of I-type pluton, as well as their comparisons with those of S-type leucogranites within the Çataldağ core complex, indicate heterogeneous magma sources, evolving from crust-dominated to mantle-dominated magma from Eo-Oligocene to the early Miocene, reflecting mantle upwelling beneath NW Anatolia. We infer that the long-lived, mantle-driven Eocene plutonic activity that preceded the development of core complexes may have led to thermal weakening, melting, and crustal flow in the lower-middle crust beneath NW Anatolia, facilitating the formation of the granite-gneiss-migmatite complex during the incipient phase of extension in the Eo-Oligocene. Coinciding with the rapid exhumation of the S-type granite and migmatite complex, the formation and emplacement of I-type synkinematic pluton along the detachment fault zone of the Çataldağ core complex were developed as a result of asthenospheric upwelling driven by lithospheric removal processes. This inferred lithospheric removal was triggered by Hellenic slab rollback affecting the entire western Anatolia since the Oligocene. The transition from S- to I-type granites observed in the Çataldağ core complex and other Aegean massifs may indeed be a manifestation of the intensity or accumulation of this crustal extension. [Display omitted] • Early Miocene synkinematic pluton (ÇSP) from Çataldağ Core Complex (ÇCC) crystallised in a shallow crustal magma chamber. • Enriched mantle melts and multi-component crustal end-members interacted. • S- to I-type granite transition in ÇCC occurred during core complex style extension. • Convective removal of the Western Anatolian lithosphere triggered hybrid I-type magmatism. [ABSTRACT FROM AUTHOR]

Quaternary alkali basalts and related rocks are located in the northern portion of the Sanandaj–Sirjan zone in Iran (SaSZ). These rocks, also known as the Salmas Quaternary volcanic rocks (SQVR), consist primarily of basalts and trachy basalts (mafic parts) and basaltic trachy andesites and trachy andesites (intermediate parts), which are highly sodic alkaline and high-K calc-alkaline in character, respectively. These mafic to intermediate samples contain variable proportions of pyroxene, olivine and plagioclase, alongside ubiquitous accessory levels of biotite, amphibolte and oxides. Based on the negative Nb, Ta, Zr, and Hf, and also positive Th and U anomalies in some samples, the SQVR formed in a widely-recognized syn -collision environment following the termination of oblique Neotethys subduction beneath the Central Iranian microplate. Following slab break-off of the remnants of the oceanic lithosphere under the Arabia-Eurasia collision zone, a combination of asthenospheric upwelling, small-scale mantle convection, and localized crustal extension promoted magmatism. We model that decompression melting occurred on the boundary of the lithosphere and asthenosphere at around 65–70 km. The magma of the SQVR resulted from relatively small degrees of partial melting (<5%) of a metasomatized amphibole-bearing garnet-spinel lherzolite. Fractional crystallization, combined with a small amount of assimilation and fractional crystallization occurred during transfer to the surface and resulted in the evolution of basaltic parent magmas towards intermediate compositions. Unlabelled Image • The Salmas volcanic rocks are composed of alkaline and high-K calc-alkaline basalt and andesite. • The rocks are related with a syn-collision tectonic environment. • Magma were generated by slab break-off of the remnants of Neotethys in a subduction zone. • Formation of the rocks may have involved in assimilation and fractional crystallization process. [ABSTRACT FROM AUTHOR]

Biotite granites and K-feldspar granites are the dominant intrusive rock types of the Colomine gold district in the Neoproterozoic terrain of SE Cameroon. The silica contents of these granitoids range from 68.93–75.39 wt% and Au contents from 0.6 to 32 ppb. They are weakly peraluminous (ASI = 1.0–1.2) I-type granitoids with high-K calc-alkaline to shoshonitic character, emplaced within a syn -collisional arc setting. They have fractionated trace element patterns (LaN/YbN: ~ 11–331) with enrichment in LREE compared to HREE and weak to strong negative Ba, Nb, Sr, P, Ti, Lu, and Eu (Eu/Eu* = 0.12–0.52) anomalies. The geochemical characteristics suggest that the granitoids formed by partial melting of crustal source rocks with some input from greywackes. Differentiation of the hydrous parent magma was characterized by fractionation of muscovite, biotite, hornblende, plagioclase, and K-feldspar with minor zircon, apatite and Fe-Ti oxide. Mafic garnet-bearing inclusions represent an early crystallization phase that was incorporated in the later felsic melt. The granitoids became emplaced into Proterozoic schist belts. Along the contacts, they became brecciated, sheared, foliated and sericitized. These "contact granites" have higher gold contents (5–32 ppb) than the fresh granitoids (0.6–3 ppb). Remobilisation of gold from early magmatic sulfide minerals by post-magmatic hydrothermal fluids enriched the shear-related granitoids. Hydrothermal alteration results to enrichment in Cu, Ni, Cr, Mo, Ga, V, Tl, and Au and depletion in LREE (e.g., La, Ce, Pr). Micro-shear and fault zones in the vicinity of the granitoids constitute favourable sites for exploration. • Biotite and K-feldspar granites are the dominant rocks in the Colomine area, SE Cameroon. • They are weakly peraluminous, high-K calc-alkaline to shoshonitic, I-type granitoids derived from partial melting of crustal material. • These granitoids were emplaced into Proterozoic schist belts and became brecciated, sheared, foliated and sericitized along the contacts. • The fresh granitoids have relatively low Au values compared to areas of the pluton affected by post magmatic hydrothermal alterations. [ABSTRACT FROM AUTHOR]

A combination of zircon U–Pb ages, whole-rock geochemistry, Sr–Nd isotopes, and in situ zircon Hf isotope, for newly found felsic igneous rocks from the Hongshanliang copper deposit district in the Aqishan-Yamansu belt, NW China, are presented to investigate the petrogenesis and tectonic or even crustal evolution of the Eastern Tianshan during the Late Paleozoic to the Early Mesozoic. Zircon U–Pb ages show two phases of igneous activity in the Early Carboniferous (348.8 ± 2.1 Ma and 343.3 ± 2.3 Ma for rhyolite and granite porphyry) and the Triassic (250.2 ± 3.5 Ma and 235.7 ± 2.4 Ma for (monzonitic) granodiorite and monzogranite) in the Hongshanliang copper deposit district. The Carboniferous granitic rocks are enriched in Rb, Ba, and Pb, and depleted in Nb and Ta, with low Sr/Y ratios, showing arc-related affinities. Dominantly positive ε Hf (t) values (+2.55 to +7.15 and +1.54 to +5.03 for the rhyolite and granite porphyry, respectively), crustally-derived geochemical elements ratios (e.g., Nb/Ta, Th/U, Ta/U, and Th/La) and Mg# values (< 37), combined with ε Nd (t) values (−0.1 to +0.6 and −0.3 for the rhyolite and granite porphyry), suggest the Carboniferous granitic rocks were derived from partial melting of the Mesoproterozoic lower crust with mantle-derived magmas involvement. The Triassic (monzonitic) granodiorite and monzogranite are medium-K calc-alkaline, enriched in LILE, and depleted in HFSE, with high SiO 2 , Al 2 O 3 , Sr, and Sr/Y, and low Y and HREE values, characteristic of adakite-like rocks. The Triassic granitoids have low MgO, TiO 2 , Cr, Co, and Ni contents and high Fe 2 O 3 T/MgO ratios (3.07–3.23), with geochemical features of juvenile crust (e.g., low Nb/U and Ta/U ratios and depleted ε Hf (t) values) and mantle-derived magmas (e.g., high Th/U and Th/La ratios and Mg# values), which suggests that the Triassic granitoids were derived from partial melting of thickened juvenile lower crust with minor mantle-derived components. Integrating published cognition and our work, we propose that the Aqishan-Yamansu belt underwent a tectonic transition from an Early Carboniferous fore-arc basin extensional setting to a Triassic within-plate one. Early Carboniferous granitic magmas were emplaced during the southward subduction of the Kangguer oceanic slab and Triassic granitoids were formed after later collision between the Dananhu-Tousuquan island arc and the Yili-Central Tianshan block. Moreover, we also conclude that the major crustal growth in the Eastern Tianshan occurred at ca. 444–270 Ma and was accompanied by abundant Fe–Cu–Ni–Au mineralization, with crustal reworking at ca. 250–200 Ma. Unlabelled Image • Two phases of igneous activity documented in the Hongshanliang copper deposit area. • Carboniferous granitic rocks mainly formed by partial melting of the Mesoproterozoic lower crust. • Triassic granitoids predominantly formed by re-melting of thickened juvenile lower crust. • The Aqishan-Yamansu belt underwent a Carboniferous to Triassic tectonic transition. • The Eastern Tianshan underwent crustal growth (444–270 Ma) and reworking (250–200 Ma). [ABSTRACT FROM AUTHOR]

Widespread leucogranites in the Himalayan orogenic belt are thought to have originated by in situ partial melting of the Greater Himalayan Crystalline (GHC) when it underwent high-grade metamorphism during Cenozoic orogenesis. Therefore, the leucogranites and associated migmatites can be used to constrain the exhumation history of the GHC. However, the petrogenetic relationship between the GHC, leucogranites, and migmatites is not well-constrained. As such, we carried out a detailed petrographic, mineralogical, geochronological, and geochemical study of leucosomes and leucogranites from the Nyalam region in southern Tibet. Monazite U–(Th)–Pb dating indicates that anatexis of the GHC occurred during the late Eocene and Miocene (40–14 Ma), whereas leucogranite emplacement occurred from 27 to 14 Ma. There are marked differences between the leucosomes in migmatites and leucogranites in terms of field geology, mineralogy, and geochemistry, suggesting different origins. The leucosomes occur mainly as pockets or are interlayered with melanosomes in stromatic metatexites. The leucosomes contain oligoclase and Fe-rich biotite, and have whole-rock compositions with high K 2 O contents (4.8–7.4 wt%) and K 2 O/Na 2 O ratios (1.35–2.97), positive Eu anomalies (Eu/Eu* = 0.93–2.61), and low rare-metal (Li, Be, Cs, Sn, and Ta) contents. These features are consistent with an origin by muscovite dehydration melting of the GHC. However, the leucogranites intrude the GHC and occur as small plutons along the South Tibetan Detachment System. In contrast to the leucosomes, the plagioclase and biotite in the leucogranites are albite and siderophyllite, respectively. The leucogranites have relatively low K 2 O (4.3–4.7 wt%) contents and K 2 O/Na 2 O ratios (1.04–1.24), high rare-metal contents, and marked negative Eu anomalies (Eu/Eu* = 0.47–0.70), indicating an origin by extensive fractional crystallization. We propose that the leucogranites were magmas produced in the deeper GHC during peak metamorphism, and subsequent extensive fractional crystallization occurred during long-distance, upward migration of magma along the South Tibetan Detachment System (STDS) during exhumation of the GHC. During these processes, the high-grade metamorphic rocks of the GHC were partially melted, resulting in the formation of leucosomes within migmatites. Therefore, the leucosomes and leucogranites have different origins and should be considered separately in studies of Himalayan orogenesis. Unlabelled Image • Leucosome and leucogranite in the Nyalam region involve different petrogenesis. • Leucosome is a product of in-situ muscovite dehydration melting. • The composition of leucogranite was changed by fractional crystallization. • Formation of leucogranite does not relate to in situ melting of metasedimentary rocks. [ABSTRACT FROM AUTHOR]

The Archean (~2.6 Ga) Siilinjärvi carbonatite complex in east-central Finland is crosscut by a few ultramafic lamprophyre dykes, together with a broad array of more evolved mafic dykes that range in composition from foidites to various types of alkali basalts. A possible genetic link between the primitive lamprophyres and the carbonatite complex has previously been hypothesised, but their exact relations have been unclear due to the regional metamorphic overprint (i.e., greenschist facies). Here we focus on the petrology and petrography of the mafic dykes, and integrate the data to present a coherent model that can explain the genesis of the Siilinjärvi carbonatite complex. Field-relations, in combination with petrography and geochemistry, indicate that there are at least three generations of mafic dykes present. The oldest dykes (Generation I) are strongly deformed, and inferred to have been emplaced shortly after the formation of the complex itself. These dykes can be divided into two groups (i.e., ultramafic lamprophyres and Group A), where Group A comprises foidites characterised by low SiO 2 (41.4–51.5 wt%) and high alkali (>10 wt% K 2 O) content. We interpret the foiditic magmas to have evolved from primitive ultramafic lamprophyres by fractionating a clinopyroxene-olivine dominated mineral assemblage that was devoid of feldspar. This fractionation path forced alkali-enrichment in the magmas belonging to Group A, which pushed them into the miscibility gap, and resulted in liquid immiscibility that produced moderately alkaline conjugate carbonatite(s). Subsequent fractionation of the conjugate carbonatite by predominantly calcite and apatite produced the mineralogically homogeneous carbonatite cumulate that is exposed at Siilinjärvi. Younger, less deformed, mafic dykes (belonging to Generations II and III) exhibit trace element characteristics, broadly similar to basaltic dyke swarms in the region. The younger dykes are characterised by the presence of large plagioclase crystals in thin sections. Crystallisation of a feldspar-bearing mineral assemblage resulted in only moderate enrichment of alkalis with increased fractionation, which caused the younger dykes to evolve along the more common basalt-to-trachyte series. Thus, the magmas belonging to Generations II and III at Siilinjärvi never fulfilled the conditions required to produce carbonatites by liquid immiscibility. [ABSTRACT FROM AUTHOR]

Tectonic mélange fragments (metabasalt and metadiabase) in the ophiolitic serpentinites of the Egyptian Eastern Desert show peculiar mineral assemblages and they provide useful insights into metamorphism and metasomatism. New field and mineralogical data indicate the formation of rodingite at the expense of mid-ocean ridge basalt (MORB) at three localities, namely Wadi Sikait, Wadi Abu Rusheid and Hafafit (SRH belt). These rocks occupy a lower structural horizon in the tectonic mélange zone(s), whereas ocean-island and arc basalt and diabase (OIB) is relatively younger with no evidence of rodingite formation. Rodingitization starts at slow-ultraslow spreading centers and continued until subduction and exhumation at an accretionary wedge. It is a process that is characterized by Ca-rich fluids and the development of a complicated "blackwall" due to superimposed K+ and Mg2+-metasomatism. Oxygen fugacity is fluctuating where it is high for Hafafit and low for Wadi Abu Rusheid rodingites. The Ta/Yb-Th/Yb ratios suggest that rodingitization is not contemporaneous with serpentinization in an island-arc environment but with serpentinization near seamounts at the spreading centers. Combined field observations, whole-rock geochemistry and mineral chemistry data prove that rodingites are formed at the expense of a MORB (mid-ocean basalt) protolith and occupies a lower structural position than unrodingitized IAT (island-arc tholeiite) metadiabases. Unlabelled Image • Ophiolitic fragments are common in the mélanges of the Eastern Desert. • Fragments originating from MORB are transformed into rodingites. • Rodingitized fragments are distinctly metamorphosed and occur at Sikat and Hafafit areas. • Medium- and high-pressure assemblages are characteristic for rodingitized fragments. • Metadiabse fragments are island-arc tholeiites that occupy a higher horizon and unrodingitized. [ABSTRACT FROM AUTHOR]

Earth's plate tectonic system was initiated between 3.0 and 2.5 Ga and became the dominant regime for crustal growth and differentiation. However, it is unclear whether subduction–accretion processes, including slab rollback, occurred regionally in the area of the western Shandong Province Granite–Greenstone Terrane of the North China Craton (NCC) during the early development of plate tectonics. We quantified petrology, whole-rock geochemistry, and zircon U–Pb–Hf isotopes for felsic, mafic, and ultramafic rocks from the Yishui Complex (YC) in the NCC to constrain the origin of these rocks and the associated tectonic setting(s). The granites yield 207Pb/206Pb ages of 2509 ± 20 to 2484 ± 26 Ma, and magmatic zircon grains from these rocks have εHf(t) values of 0.6–6.4. The coeval mafic–dioritic rocks represent the fractional crystallization products of a primary magma that was derived from low-degree (<7%) partial melting of a metasomatized mantle source. The granodiorites were derived from the partial melting of oceanic slab material, with slab melts being contaminated by mantle wedge material during their ascent. The high-K granites represent the crustal reworking products of regional tonalite–trondhjemite–granodiorite and sedimentary rocks. Late Neoarchean magmatism in the YC was related to slab subduction, and slab rollback at ~2.50 Ga led to the generation of potassic rocks, coeval mafic–ultramafic xenoliths, and granulite metamorphism with a counterclockwise P–T–t path in the Yishui area. • The mafic–dioritic rocks were melting products of metasomatized mantle. • The granodiorites originated from slab melts that contaminated by mantle. • The high-K granites were generated from crustal reworking. • Late Neoarchean magmatism in the YC was related to slab subduction. [ABSTRACT FROM AUTHOR]

Collisional zones are commonly considered as important regions for crustal reworking, but the reworking mechanism remains debated. The well-known Himalayan-southern Tibetan orogen, built by India-Asia collision and convergence, has the thickest continental crust on Earth and is therefore an ideal region for studying crustal reworking during collisional orogenesis. Here we revisit the Miocene high-silica potassic rocks (trachytes) in the Konglong area of the central Lhasa block, southern Tibet. Integrated studies of geochronology, mineral compositions, bulk-rock major- and trace-element geochemistry, and Sr-Nd-Pb-Hf-O isotopes unequivocally indicate that the Konglong trachytes formed by mixing between enriched mantle-derived ultrapotassic and thickened ancient crust-derived magmas. Combined with post-collisional magma mixing recently identified in the southern Lhasa block, we suggest that magma underplating and subsequent mantle-crust interaction (i.e., the matter and energy transfer from the mantle to the crust) has been a common and important crustal reworking process in southern Tibet during Indian continental subduction. This process may be related to Indian plate flat subduction and subsequent foundering during the post-collisional stage. In combination with the nature of Cenozoic magmatism in the Himalaya block, we suggest that in addition to partial melting of the subducted continental crust, magma underplating and subsequent crust-mantle mixing beneath the obducted continent has also played an important role in crustal reworking of the collisional zone. • Konglong Miocene trachytes formed by mixing of crustal and ultrapotassic magmas. • Magma underplating and mantle-crust interaction induced Lhasa crustal reworking. • Indian plate flat subduction and foundering controlled crustal reworking. [ABSTRACT FROM AUTHOR]