Continental arcs have been proposed as major sites of continental crust generation because their calc-alkaline compositions resemble those of the bulk continental crust. However, the actual contribution of continental arc magmatism to crustal growth remains highly debated. Here, we present integrated zircon U-Pb ages and Lu-Hf isotopes from sixteen samples of late Paleozoic granitoid plutons from the northern margin of the North China Craton (NCC) to evaluate the role of continental arcs in crustal growth. The plutons yield crystallization ages of 315-272 Ma and contain abundant inherited zircons with ages of similar to 2.5 Ga and similar to 1.9-1.8 Ga, corresponding to major tectonothermal events in the NCC basement. Magmatic zircons show predominantly negative epsilon(Hf)(t) values ranging from -20.6 +/- 0.3 to -6.0 +/- 0.4 and two-stage Hf model ages of 2.8-1.6 Ga, indicating derivation from ancient crustal sources. Simple binary Hf isotope mixing calculations indicate that the melt requires a dominant crustal component, with juvenile mantle-derived material contributing no more than 37% for the least evolved pluton (the Daguangding pluton) and < 18% for the other plutons. Large inter-pluton but limited intra-pluton Hf isotopic variations (less than 5 epsilon units, mostly <3 epsilon units) are best explained by source heterogeneity within the NCC lower crust, involving variable proportions of Neoarchean and Paleoproterozoic crustal domains. Our results demonstrate that late Paleozoic continental arc magmatism represents large-scale reworking of Archean-Paleoproterozoic crust with minimal addition of juvenile mantle-derived material. Comparison of the Gangdese arc, the Andean arc, and the northern NCC shows that continental arcs built on ancient cratons contribute little to crustal growth, and that post-Archean continental crust formed mainly in oceanic arcs prior to arc-continent collision. Continental arc magmatism primarily reworks and homogenizes pre-existing continental crust rather than producing new crust.

Caldera-forming eruptions commonly involve the simultaneous eruption of multiple silicic magmas with heterogeneous compositions. The physical conditions under which these different silicic magmas are generated and stored and what triggers their eruption are essential questions in understanding the ability of such magma reservoirs to become rejuvenated and erupted. In our study, we investigate the petrogenetic relationships between plutonic and volcanic rocks from the Xiaoxiong Caldera in Southern China. Our results show that two compositionally distinct magma reservoirs were emplaced contemporaneously at 87.3 +/- 0.3 Ma beneath the caldera but resided at different crustal levels. Low-silica rhyolite, trachyte, and porphyritic quartz monzonite were derived from a deeper reservoir located at similar to 19-30 km, whereas high-silica rhyolite and porphyritic granite were extracted from a shallower reservoir at similar to 7-9 km depth. Magma recharge induced thermal rejuvenation of these two pre-existing, cold, and non-eruptive reservoirs, promoting crystal-melt segregation and ultimately triggering the eruption of compositionally diverse silicic magmas. When the parental magmas of low-silica rhyolite, trachyte, and porphyritic quartz monzonite are extracted from a deep reservoir in the middle to lower crust, the system remains undersaturated in both water and zircon. Upon ascent to the shallow crust, these magmas subsequently reach saturation with respect to water and zircon. In contrast, prior to the extraction of high-silica rhyolite from the upper crustal reservoir, both the high-silica rhyolite and porphyritic granite had reached saturation in zircon and water. Following extraction, the high-silica rhyolite experienced significant degassing. Our results reveal that melts stored at different depths beneath the same volcanic caldera can remain in a cold, quiescent state for extended periods. Subsequent late-stage reheating rejuvenates these reservoirs through distinct mechanisms, leading to the generation of magmas with divergent geochemical features and evolutionary histories prior to eruption.

Triassic alkaline magmatism is widespread across the North China Craton (NCC), occurring along its northern margin, the Liaodong–Jiaodong–North Korea region, and the Lesser Qinling orogen. These rocks can be broadly grouped into syenitic complexes, mafic dikes, and carbonatites. They were derived from low-degree partial melting of a volatiles-bearing clinopyroxene-rich subcontinental lithospheric mantle (SCLM) within the garnet stability field, followed by varying degrees of fractional crystallization and crustal assimilation. Integrated zircon Hf-O isotopes, together with whole–rock geochemical and radiogenic isotopic data, indicate that the SCLM beneath the NCC underwent spatially heterogeneous metasomatism. Beneath the northern margin and the Lesser Qinling orogen, mantle enrichment is attributed to melts or fluids derived from subducted oceanic crust and sediments, linked to the Paleozoic–early Mesozoic subduction of the Paleo-Asian and Paleo-Tethyan oceans, respectively. In contrast, the Liaodong–Jiaodong-North Korea region records modification by recycled continental crustal materials, associated with the Triassic deep subduction and subsequent exhumation of the Yangtze Craton. This pervasive metasomatism introduced abundant fertile components and volatiles into the SCLM, thereby weakening its rheological and physical properties. Together with subsequent modification related to Paleo-Pacific plate subduction, these processes likely promoted lithospheric instability and contributed to the ultimate destruction of the NCC at ca. 120 Ma.

Apatite is a robust recorder of open-system magmatic evolution in granitoids, as it may preserve subtle geochemical signals of magma compositional changes. Here, we integrate textural, compositional, and O-isotopic analyses of magmatic apatite from Jurassic granodiorites and biotite granites in the Cathaysia Block, Southeast China, to better constrain the nature and evolution of open-system magmatic processes and refine the petrogenesis of these granitic rocks. In granodiorites, O-isotope disequilibrium between apatite and zircon documents open-system magmatism: low-δ18O apatite (Group 1; 5.7–7.1‰; Δδ18O_zircon–apatite = +1.31‰) indicates greater mantle-derived input, whereas high-δ18O apatite (Group 2; 8.0–9.0‰; Δδ18O_zircon–apatite = -0.84‰) reflects enhanced supracrustal assimilation. In biotite granites, apatite and zircon are in near isotopic equilibrium (Group 3; 6.3–9.0‰; Δδ18O_zircon–apatite = -0.08–0.09‰ ), and δ18O differences among samples likely reflect variable proportions of mantle- and crust-derived components. Apatite core–rim zoning provides additional evidence for complex magma interaction: apatite in granodiorites shows abrupt core-to-rim decreases in REE, Y, and SiO2, consistent with mafic recharge, while apatite in biotite granite displays opposite trends, reflecting hybridization with congenetic, more evolved felsic melts. Apatite trace-element systematics further track mineral–melt differentiation during magma evolution: decreasing Sr coupled with increasingly negative Eu anomalies reflects plagioclase fractional crystallization, whereas pronounced LREE depletion in apatite indicates early allanite crystallization. Together, these in situ textural, geochemical, and O-isotopic data highlight apatite as a powerful tracer of magma sources, open-system evolution, and differentiation processes in granitoids.

The Nyainqentanglha Range is dominated by a composite batholith formed during post-collisional magmatism following the India-Asia collision. Recent studies have identified widespread beryllium mineralization in Early Miocene granites and pegmatites in its western range, highlighting the significant rare-metal metallogenic potential within this batholith. This study presents a systematic investigation of the geochronology, petrology, mineralogy and geochemistry of the granites exposed in the Labupu area on the western margin of the Nyainqentanglha Range, a region that has received relatively limited attention. Zircon U-Pb dating results indicate that magmatic activity in this area occurred in two main stages, the Early Oligocene (similar to 30Ma) and the Miocene (ca. 13 similar to 12Ma and ca. 10 similar to 9Ma), respectively. Notably, significant niobium mineralization developed in the Late Miocene granites (ca. 10 similar to 9Ma), which are dominated by biotite monzogranite with minor highly fractionated aplite veins. Aplite exhibits higher SiO, and lower MgO, FeOT, TiO2, CaO, P2O5, REE, Zr, HI, and Th contents than biotite monzogranite, reflecting fractional crystallization of mafic minerals, plagioclase, and accessory phases such as apatite, zircon, and monazite. The aplites exhibit Zr/Hf (13.3) and Nb/Ta (5.42) ratios that deviate from the average continental crust values, along with tetrad effects in rare earth elements. Combined with the widespread silicification observed in the biotite monzogranites, these features indicate that the magmatic system has evolved to a magmatic-hydrothermal transitional state or even hydrothermal state before solidification. Zircon Hf isotopic compositions show a relatively wide range with predominantly negative epsilon(Hf)(t) values (10.0 similar to+4.1), suggesting that the magmas were mainly derived from remelting of the ancient crystalline basement of the Central Lhasa Terrane, with possible minor contributions from depleted mantle or juvenile crust. The primary niobium-bearing minerals in the Late Miocene granites are Nb-rich rutile and euxenite. Based on mineral assemblages and textures, the Nb-rich rutile can be classified as magmatic or hydrothermal in origin. Magmatic rutile contains 0.51%similar to 1.50% Nb2O3, whereas hydrothermal rutile contains up to 17.1% Nb2O3, indicating that niobium was initially enriched during the magmatic stage and further concentrated to anomalous levels during the magmatic-hydrothermal transitional or hydrothermal stage. Euxenite in the Late Miocene Labupu granites belongs to the polycrase subgroup, which formed during the early magmatic-hydrothermal transitional stage, reflecting the saturation of Nb, Y, and REE in the melt. These polycrase grains commonly exhibit Ta- and U-rich rims, suggesting crystallization from a more evolved, Ta-U-enriched fluid. Furthermore, some polycrase grains in the biotite monzogranite exhibit oscillatory zoning, recording long-term magmatic differentiation and episodic magma recharge processes. This study reveals significant niobium mineralization potential in the Nyainqentanglha region, with the first identification of NYF-type (Nb-Y-F) rare-metal mineralization, providing important new insights for rare-metal exploration on the Tibetan Plateau.

High-silica plutons (SiO2 > 75wt.%) play a key role in deciphering the evolution and origin of the upper continental crust. Therefore, studying vertical cross sections of high-silica plutons is essential for gaining new insights into magmatic evolution and the thermal and material processes that shape the Earth's crust during pluton formation. In this study, we present extensive data on the bulk-rock geochemistry, zircon U-Pb ages, Hf isotopes, and trace elements for a range of high-silicic rocks from top-to-bottom cross-section in the Jiuzhen batholith and Yunhe pluton in southeastern China. Geochemical and zircon trace element features of the granitic rocks from the Jiuzhen batholith and Yunhe pluton indicate that these high-silica rocks originated from middle- to upper-crustal magma reservoirs via crystal-melt segregation. In the Jiuzhen batholith, the coarse-grained porphyritic granite in the upper unit originated from the reactivation of a pre-existing, highly evolved, water-rich magma reservoir with lower crystallinity, while the coarse-grained porphyritic granite in the lower unit was segregated from the same magma reservoir with higher crystallinity and involved a higher proportion of mantle material in its formation. The fine-grained granite was later extracted from the nearby magma reservoir of coarse-grained porphyritic granite in the upper unit, indicating they were formed through in-situ differentiation of the silica magma reservoir in the shallow crust. Similarly, the geochemical characteristics of granites from different units of the Yunhe pluton suggest they were produced by the solidification of high-silica melts extracted from a common water-poor magma reservoir. As the high-silica magmas accumulated to form a magma reservoir in the shallow crust and subsequently underwent further cooling and crystallization, the proportion of melt decreased, leading to an enrichment of volatiles and silica in the residual melt. The upward migration of these residual melts within the high silicic magma reservoir resulted in vertical compositional variations within the Yunhe pluton. Our research on the Jiuzhen batholith and Yunhe pluton has revealed that the composition of high-silica magmas is influenced not only by crystal-melt segregation within deep magma reservoir but also by in-situ crystal-melt segregation occurring within magma reservoirs formed through the aggregation of felsic melts in the shallow crust.

Silicic magmatism was extensively developed in the coastal regions of southeast China. The abundant volcanic fields and granitic plutons in this region provide exceptional opportunities to investigate upper crustal magmatic processes and their evolution. We investigate the petrogenetic connections among alkali feldspar granites (AFGs), porphyritic enclaves, porphyritic rocks (including porphyritic monzonites and porphyritic syenites), and rhyolites from the Yandangshan caldera and surrounding area using zircon U-Pb dating, trace elements, Hf isotopic ratios, and bulk-rock geochemistry. Zircon U-Pb dating reveals that the plutonic and volcanic rocks of the Yandangshan caldera crystallized concurrently (98-102 Ma), with consistent Hf isotopic compositions and trace element trends in low-U zircons further supporting that lithological variations within the caldera result from crystal-melt segregation. The porphyritic rocks and enclaves are rich in Sr and Ba, display high Zr/Hf ratios, and show positive to weakly negative Eu anomalies, suggesting they represent cumulate residues from crystalmelt segregation. The AFGs and rhyolites are enriched in Rb but exhibit depletions in Sr, Ba, and Eu, characterized by low Eu/Eu* and high Rb/Sr ratios. Both units are interpreted as evolved silicic melts extracted from a crystal-rich magma reservoir. Compared to the erupted rhyolites, the AFGs display higher silica content and Rb/ Sr ratios, along with lower Eu/Eu* ratios. Moreover, high-U zircons are exclusively found in the AFGs and exhibit the most evolved trace element signatures within the entire suite, characterized by elevated Hf and U concentrations, as well as low Eu/Eu* ratios. These characteristics indicate that the AFGs, which exhibit A-type features, are more evolved than the rhyolites, reflecting extended in-situ crystallization and differentiation following the eruption of the rhyolitic magmas. We propose that the magma responsible for the AFGs originated from the underlying feldspar-rich mush, following the rhyolite eruption. These melts then underwent in-situ crystallization and melt differentiation, leading to the formation of A-type granites that are more evolved than the rhyolites. By comparing the geochemical characteristics of contemporaneous silicic plutonic and volcanic rocks from southeastern China, we demonstrate that large volumes of high-silica granitic magma accumulated after silicic melt eruptions. Our study further reveals that the compositional diversity of A-type granites primarily results from crystal-melt segregation processes rather than distinct magma sources, emphasizing the importance of shallow crustal differentiation in granite formation. Recognizing these processes enhances our understanding of how similar geological mechanisms generate diverse granite compositions across various tectonic environments, ultimately deepening our insight into the evolution of silicic magmas within the Earth's crust.

The geochemistry of lithium and boron isotopes is widely applied to a variety of Earth science disciplines. In situ measurement of Li and B isotope ratios requires matrix-matched reference materials for calibration, method validation and inter-laboratory data comparison. In this study, we characterise the Li and B isotope ratios (delta Li-7 and delta B-11) of the seven glass reference materials OJY-1, OH-1, OA-1, CGSG-1, CGSG-2, CGSG-4 and CGSG-5. These seven materials exhibit relative homogeneous delta Li-7 and delta B-11 values at the spatial resolution of 10-120 mu m, as revealed by multiple spot analyses using LA-MC-ICP-MS (n = 80-100) and SIMS (n = 8-12) on different grains. The 2s of delta Li-7 and delta B-11 in these materials as determined by LA-MC-ICP-MS and SIMS ranges from similar to 0.40 to similar to 1.50 parts per thousand. The recommended delta Li-7 and delta B-11 values were determined using solution MC-ICP-MS techniques, and data from independent laboratories showed high precision with discrepancies within similar to 1.50 parts per thousand. The Li and B mass fractions of the various glasses differ, ranging from similar to 40 mu g g(-1) to 2000 mu g g(-1) and similar to 40 mu g g(-1) to 5000 mu g g(-1), respectively. The various glasses also have different delta Li-7 and delta B-11 values, ranging from +0.99 to +5.69 parts per thousand and -10.92 to +0.25 parts per thousand, respectively. Notably, OA(-1) and OH-1 are high-silica glasses (SiO2 > 75% m/m) and, therefore, may be particularly helpful for Li and B isotope analysis of highly evolved magmatic rocks. These investigated glasses have great potential as reference materials for the in situ measurement of Li and B isotope ratios.

Aluminous A-type granites are not typically associated with mantle-derived rocks. Their generation is usually linked to crustal melting with mantle-derived magmas primarily acting as a heat source. However, the Triassic Bolinchuan A-type granites on Liaodong Peninsula, northeastern China, coexist with a large mantle-derived alkaline igneous complex, indicating a close genetic relationship that provides new insights into the petrogenesis of aluminous A-type granites. The Bolinchuan granites were formed during 230-226 Ma, coeval with syenites in the alkaline complex (230-224 Ma). The granites are metaluminous to weakly peraluminous, but have relatively high alkali contents (8.61-9.40 wt%). Their high Ga/Al ratios, elevated Nb, Zr, Ce, and Y contents, and high magmatic temperatures (>875 degrees C) indicate an affinity with aluminous A-type granites. However, the Bolinchuan granites have relatively high MgO contents at intermediate SiO2 contents, with Mg# values of up to 47; these features are inconsistent with the melting of only crustal rocks. Instead, these granites contain mineral phases similar to those of the syenites and exhibit major and trace element trends that are continuous with those of the syenites. Their geochemical features include enrichments in large-ion lithophile elements (e.g., Ba and Sr), depletions in high-field-strength elements (e.g., Nb and Ta) and heavy rare earth elements, and small negative Eu anomalies, which are also consistent with the features of the associated syenites. Furthermore, the granites and their accessory minerals have high initial Sr-87/Sr-86 ratios, and low epsilon(Nd)(t) and epsilon(Hf)(t) values, which are similar to the syenites, apart from being slightly less isotopically enriched. These geochemical and isotopic features suggest the Bolinchuan granites formed from the syenitic magmas by fractional crystallization of alkali feldspar, amphibole, and apatite, in combination with the addition of similar to 30 % juvenile crust-derived materials, as indicated by modeling. Our study reveals that differentiation of mantle-derived alkaline magmas can generate magmas parental to aluminous A-type granites. As such, the mantle not only provides the heat for the formation of aluminous A-type granites, but can also be the main source of the magmas.

Previous studies indicate that significant amount alkaline rocks, primarily consisting of quartz syenite and quartz monzonite, were formed during the late Early Cretaceous to early Late Cretaceous in the coastal area of southeastern China. However, their origin is still controversy. To determine the genesis of these rocks, this study focused on the quartz monzonite in the Matou pluton in western Zhejiang and conducted detailed investigations of whole-rock major and trace element analysis, mineralogical scanning, zircon U-Pb geochronology, zircon Hf isotopes, zircon trace elements, apatite trace elements and plagioclase electron probe analysis on it. The zircon U-Pb dating reveals that the Matou pluton formed at 100 +/- 1 Ma, representing a product of magmatic activity during the late Early Cretaceous. Field observations found abundant mafic enclaves within the Matou pluton. Combining the zircon Hf isotopic data (epsilon(Hf)(t) = -10.4 similar to -0.4), it is suggested that the Maiou pluton resulted from the magma mixing of felsic magmas derived from ancient continental crust and mafic magmas derived from the mantle. Zircons in the Matou monzonite show complex textures, commonly displaying a black core, a white mantle, and black rims in CL (cathodoluminescence) images. The earliest black zircon cores exhibit relatively high Th, U, Hf contents, varying Eu/Eu* (0.50 similar to 0), Zr/Hf (40 similar to 70) and Th/U ratios, as well as Ti content. This suggests that they crystallized from a high-degree, low-temperature, and highly crystalline silicic magma reservoir in the crust. The white mantle zircons have lower Th, U, Hf contents, and relatively higher Eu Eu ratios (0.15 similar to 0.37) which indicates that injection of mafic magma caused reactivation and melting of pre-existing magma reservoirs, leading to an increase in temperature and melt proportion within the reservoir. As minerals continued to crystallize and felsic melt extraction occurred, the remaining felsic melt within the magma reservoir underwent significant evolution. This led to the crystallization of the latest-stage black zircon rims characterized by high U and Hf contents and low Eu Eu and Zr/Hf ratios. Electron probe data on plagioclase suggests, as plagioclase phenocrysts crystallized, the magma reservoir underwent a crystal-melt separation process, causing the evolution of melt from being rich in calcium to being rich in sodium. Ultimately, this led to the crystallization of fine-grained quartz and sodium feldspar. Apatite in the quartz monzonite has low Sr content (113 x 10(-6) similar to 417 x 10(-6)), high U, Y and light rare earth element, and low heavy rare earth element contents. This implies that, after reactivation, the pre-existing magma reservoir also underwent crystal fractionation of minerals such as plagioclase, titanite and apatite. Zircon records the reactivation and melting processes of the magma reservoir, while minerals like plagioclase and apatite only record the crystal-melt separation and melt extraction processes after the reactivation of the reservoir. Therefore, the Matou quartz monzonite suggests that it represents a residual magma reservoir that underwent melt extraction after reactivation, with contemporaneous high-silica rhyolite (or high-silica granite) representing silica-rich melt extracted from the magma reservoir. Finally, our study indicates that the magma reservoir predominantly existed in a low-temperature, low-melt proportion state

The Late Mesozoic magmatic belt in southeastern (SE) China, stretching over 1300 km, resulted from southwestward subduction of the paleo-Pacific plate. Our study focuses on the origin of Early Cretaceous syenite and A-type granite in SE China, utilizing zircon U-Pb and Hf isotopic analyses, bulk-rock compositions, and Nd-Hf isotopic compositions. Findings indicate that-142 Ma silica-unsaturated syenites in the southwest form through small degrees of partial melting of the metasoma-tized lithospheric mantle, while-142 Ma A-type granites originate from partial melting of juvenile felsic rocks. The-130 Ma A-type granites in the northeast result from mixing of ancient crustal-derived magma and mantle-derived magma. The southwest and northeast regions display distinct magmatic his-tories, with flare-ups and lulls occurring at different times. These variations suggest diverse extensional and compressional histories. A spatially migrating extensional regime is observed from the southwest (-147 Ma) to the northeast (-120 Ma) of SE China. Magmatic flare-ups in the southwest involve rework-ing juvenile crust, while in the northeast, they modify ancient crust, likely related to paleo-Pacific plate subduction and northeastward slab rollback. Slab subduction rate correlates strongly with observed geo-logical events, indicating diachronous crustal extension, magmatic flare-ups, and lulls during ca. 147- 110 Ma due to northeastward slab rollback and changing subduction rate.(c) 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

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

Magmatic activity in the syn-collision stage is key for net crustal growth. To understand the mechanism of accretion–differentiation and compositional change of the continental crust, it is important to focus on the magmatic activity during the syn-collision stage. Early Eocene mafic–ultramafic rock assemblages found in the western part of the Tengchong Block resulted from a continuous series of arc magmatic evolution, thoroughly recording the continental arc magmatic system during the subduction of the Neo-Tethys Ocean and syn-collision of the Indian-Asian continents. Early Eocene hornblende gabbro–diorite in the Tengchong Block formed at 53 Ma, and the primitive magma was derived from an enriched mantle source due to the enriched Nd–Hf isotopes. The amphibole and biotite thermobarometer measurements indicate that the mafic magma reservoirs in the Tengchong Block occurred at a mid-upper crust. Petrography, amphibole Fe/Mg exchange coefficient (KD), Rayleigh fractionation, and equilibrium melt calculation indicate that the Early Eocene hornblende gabbro–diorite in the Tengchong Block was created due to plagioclase-dominated accumulation at the mid-upper crust level. Based on the calculation, the corresponding amphibole equilibrium melt is more silicic (dacitic–rhyolitic in composition) than the bulk rocks, indicating a more evolved composition in the mid-upper crust. Three types of plagioclases reveal the multi-recharging and dissolution–reprecipitation promoting the further evolution of these mafic rocks. Therefore, this study concludes that magma recharge and plagioclase-dominated accumulation processes may be important mechanisms for the formation and evolution of mafic magma and the further crustal differentiation at the mid-upper crust level in a continental margin arc.

A new natural epidote reference material, PSV, sourced from Alchuri village, Shigar valley, Haramosh mountains, Gilgit, Pakistan, is characterized in this study for O and Sr isotope composition analysis by micro-beam analytical techniques.

A-type granites are peculiar rocks with mineralogical and geochemical characteristics that distinguish them from subduction-related calc-alkaline granites. Although many models have been proposed by previous studies, their genesis remains highly controversial. In this study, we synthesize the data (chronology, geochemistry, and isotopes) of Early Cretaceous volcanic-intrusive complexes, A-type granites, and related granitic rocks from the Gan-Hang belt and attempt to establish the genesis connection between the volcanic rocks and intrusive rocks, and thus to constrain the origin of these A-type granites. For the volcanic-intrusive complexes (e.g., Xiangshan volcanic-intrusive complex), our study indicates that the felsic volcanic rocks are more felsic than the felsic intrusive rocks. The felsic volcanic rocks represent the high silicic melts extracted from a magma reservoir and the felsic intrusive rocks represent residual crystal accumulation in the magma reservoir. Furthermore, A-type granite and related granitic rocks in the Gan-Hang Belt can be divided into porphyritic granite and equigranular granite. In addition, mineralogical and geochemical features of the porphyritic granite and equigranular granite indicate that they were generated by the mixing of crustal-derived felsic melts and mantle-derived mafic magmas. The porphyritic granite and equigranular granite have similar formation ages within analytic error, identical mineral assemblages, similar Sr-Nd-Hf isotopic compositions, and consistent variations in major and trace elemental compositions, which suggests that their parental magma should come from a common silicic magma reservoir and that the lithological differences are the result of melt extraction processes. Porphyritic granites are characterized by the low SiO2 and Rb/Sr, and high Sr and Ba and Eu/Eu*, suggesting they may represent residual crystal accumulation in the magma reservoir. In contrast, the equigranular granites, which show the features of A-type granite, are characterized by the high SiO2 and Rb/Sr, and extremely low Sr and Ba and Eu/Eu*, indicating they represent high silicic melts extracted from a magma reservoir. The wide occurrence of microgranular mafic enclaves within the porphyritic granites and miarolitic cavities in the equigranular granites reveals that the injection of mantle-derived hotter mafic magma into the magma reservoir and the exsolution of volatiles from the interstitial melt rejuvenated the pre-existing magma reservoir. Subsequent extraction and upward migration of silicic melt resulting from compaction of the magma reservoir formed the high silicic A-type granites at shallow crustal levels, which left the complementary crystal residue solidified as porphyritic granite at the bottom. Our study indicates that A-type granite can be generated in the shallow magma reservoirs via crystal-melt segregation.

A-type granites are a distinctive group of igneous rocks classified based on chemical and mineralogical criteria. Although numerous theories for the origin of A-type granite have previously been proposed, their genesis re-mains highly controversial. In the current study, we present bulk-rock geochemistry and zircon U-Pb isotopes, Hf isotopes, and trace elemental data for a suite of quartz monzonite, porphyritic granite, and miarolitic alkali feldspar granite from the coastal area of Fujian, southeastern China, to evaluate the genetic link between these rocks. Zircon U-Pb dating indicates that these rocks were crystallized at similar to 94-102 Ma. Our data strongly sug-gests that lithological differences in these rocks are the result of crystal-melt segregation in the shallow crust. The quartz monzonites are enriched in Sr and Ba, with high Zr/Hf and low silica content and a weak negative Eu anomaly, representing the cumulate residue from the crystal-melt segregation of a magma reservoir. A limited fraction of zircon from the quartz monzonite has evolved trace element signatures (high Hf, Nb, Y, U; low Eu/ Eu*), indicating that the quartz monzonite represents a mixture of accumulated crystals and high silicic melt trapped in cumulate mush. The miarolitic alkali feldspar granites and porphyritic granites are enriched in silica and Rb, and depleted in Sr and Eu. They also display low whole-rock Zr/Hf and Eu/Eu* ratios, and high Rb/Sr ratios, representing highly evolved silicic melts that were segregated from a magma reservoir. The majority of the zircon grains from the miarolitic alkali feldspar granites exhibit the most evolved trace element signatures (high Hf, Nb, Y, U; low Zr/Hf and Eu/Eu*) of the entire suite. This reveals that these zircons crystallized from the high silicic melts extracted from a magma reservoir. Magma recharge and the exsolution of volatiles from the interstitial melt have promoted the segregation and upward extraction of high silica magmas from a compacting magma reservoir in the upper crust. Our work demonstrates that the miarolitic alkali feldspar granites with A -type granite features from the coastal area of southeastern China were generated by the crystal-melt segregation process in a shallow crustal magma reservoir.

Three natural geological glasses (andesitic glass OJY-1, and rhyolitic obsidians OH-1 and OA-1) of specimen sizes 50150 g were characterised as reference materials for in situ microanalysis of major and trace elements, and Pb isotope ratios. Utilised techniques include isotope-dilution analyses by TIMS and MC-ICP-MS, bulk analyses by XRF, ICP-OES, ICPMS, and microanalysis (10-120 mu m spot size) by electron probe microanalyser, LA-ICP-MS and LA-MC-ICP-MS. Microanalyses (10-120 mu m) indicate that all three glasses are homogeneous with respect to fifty-four out of fifty-eight determined elements and Pb isotope ratios, except for Ni in OJY-1, and Cu, Zr and Ce in OH-1. The determination of reference values as well as their uncertainties at the 95% confidence level closely followed International Organization for Standardization (ISO) guidelines and the certification protocol of the International Association of Geoanalysts (IAG). These three glasses are fully natural without any subsequent heat treatment, and they represent useful additions to the widely distributed MPI-DING, USGS and CGSG reference glasses for microanalytical techniques such as electron probe microanalysis, mu-XRF, LA-ICP-MS and SIMS.

The Late Cretaceous intrusive rocks are widely distributed in the coastal area of southeastern China. These rocks can be divided into two groups : the calc-alkaline gabbro-diorite granodiorite-monzogranite-alkali feldspar granite suite aged in 115 similar to 100Ma and the alkaline porphyritic monzonite-porphyritic syenite-alkali feldspar granite suite formed in 100 similar to 86Ma. The 115 similar to 100Ma gabbros which are mainly composed of hornblende gabbros, have relatively low SiO2 ( 42. 9% similar to 53. 8% ) , alkaline, Ba, Nb, Th, Rb and Zr contents, high CaO, MgO, Al2O3, and Sr contents, low FeOT/MgO, La/Yb and Zr/Hf ratios, and high Eu/Eu* and Sr/Y. Petrographic observation and geochemical characteristics suggested that these gabbros were cumulated rocks. The diorites and microgranular mafic enclaves, which were simultaneous with the gabbros, have high SiO2 (50. 34% similar to 63. 68 %) and low CaO, P2O5, MgO, Al2O3 contents and low Eu/Eu* and Sr/Y ratios and variable La/Yb and Zr/Hf ratios. They represent the silicic melts that were extracted from a mafic crystal-rich mush. The 115 similar to 100Ma monzogranites and granodiorites are metaluminous, have variably SiO2 (61. 7% similar to 75. 3%) content. They have low FeOT/Mg0 and Ga/Al ratios and low Nb, Zr and Nb + Zr + Ce + Y contents, displaying the features of I-type granite. They have high La/Yb, Eu/Eu* and Zr/Hf ratios and Sr, Ba and Zr contents. Together with the petrographic features of the granodiorites and monzogranites, these geochemical characteristics indicates that they are the residual silicic cumulate of the crystal mush column. The 115 -100Ma alkali feldspar granites have extremely high SiO2 ( >75% ) contents, low Eu/Eu* , La/Yb, Zr/Hf and Sr/Yb ratios, low Ba, Sr and Zr contents, high Rb, Nb, Y and Th contents, and high Rb/Sr ratio. These features suggest that they were extracted from a shallow crustal crystal-rich mush. The 100 similar to 86Ma porphyritic rocks have high alkali contents (8% similar to 12% ) , low SiO2, high Zr, Sr and Ba, and low Eu/Eu*, La/Yb and Sr/Y ratios. Together with the petrographic features of the porphyritic rocks, these geochemical features suggest that these porphyritic rocks are cumulated rocks. The 100 86Ma alkali feldspar granites have extremely high SiO2 ( >75% ) contents and show the features of A-type granite. They have extremely high Rb/Sr, high Rb, Y and Th, low Ba and Sr, and low Zr/Hf, La/Yb, Eu/Eu* and Sr/Y ratios. These geochemical features suggest the high silicic granites were extracted from a shallow crystal mush. The formation of high silicic granites in the coastal area of southeastern China were closely related to the transcrustal magmatic system. The high silicic granites were extracted from a shallow crustal magma reservoir and their geochemical features were genetic related to water and volatile contents of the magma reservoir. The 115 similar to 100Ma high silicic granites with low Rb/Sr and low high field strength elements contents were extracted from a water-rich magma reservoir, which was related to the subduction of paleo-Pacific plate; while the 100 similar to 86Ma high silicic granites with extremely high Rb/Sr and high field strength elements were extracted from a volatile-rich magma reservoir, which was related to the upwelling of asthenosphere formed by back-arc extension.

Studies on the genesis and evolving mechanisms of the crustal silicic magmas are the essential way to reveal the evolving mechanisms of the continental crust both in composition and architecture. Nature and dynamic evolving processes of the silicic magma reservoir in the shallow crust are the essential factors controlling the evolvements and complexities of silicic magmas, which has been being the attractive focus and frontier of the recently researches. Basic properties and progressions in the studies of the evolvement mechanisms of the crustal silicic magma reservoir are summarized in this paper, focusing on the dynamic changes of the compositions, temperature and pressure conditions, that is, dynamic processes of residence, reactivation, fractionation and eruption of the magma reservoir driven by magma recharge. The silicic magma reservoir in the shallow crust, formed by incremental assemble, is mainly composed by magma mush, which is characterized by relatively low temperature and pressure, and high silica contents, high crystallinity and consequently high viscosity. The nature of the crustal silicic magma reservoir makes that the reservoir can only be reactivated to form evolved magmas via fractionation after long residence time or rapidly reactivated to erupt, driven by magma recharges. Recharge of mafic magmas, as well as the carrying fluid/volatile, induced dramatically changes in compositional and physical conditions of the magma system, and also the essence of the magma evolvement or eruption. Additionally, the genesis of the Mesozoic volcanic-intrusive complex in coastal area of southeast China are also discussed combined with these progressions.

Table S1: Zircon Cameca 1280 U-Pb data for the granitic rocks from SE Fujian, coastal area of SE China; Table S2: LA-ICPMS zircon U-Pb data for the granitic rocks from SE Fujian, coastal area of SE China; Table S3: Major and trace elements of the granitic rocks from SE Fujian, coastal area of SE China; Table S4: Whole-rock Sm-Nd isotopic data of the granitic rocks from SE Fujian, coastal area of SE China; Table S5: Whole-rock Lu-Hf isotopic data of the granitic rocks from SE Fujian, coastal area of SE China; Table S6: Zircon Hf-O isotopic data of the granitic rocks from SE Fujian, coastal area of SE China; Table S7: Zircon trace element of the granitic rocks from SE Fujian, coastal area of SE China.