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The paragenesis and composition of bavenite-bohseite were investigated in fifteen granitic pegmatites from the Bohemian Massif, Czech Republic. Three types distinct in their relation to primary Be precursors, mineral assemblages, morphology and origin were recognised: (1) primary hydrothermal bavenite-bohseite crystallised in miarolitic pockets from residual pegmatite fluids; and secondary bavenite-bohseite in two distinct types: (2) a proximal type restricted spatially to pseudomorphs after a primary Be mineral (beryl > phenakite, helvine-danalite); and (3) a distal type on brittle fractures and fissures of host pegmatite. The mineral assemblages are highly variable: (1) axinite-(Mn), smectite, calcite and pyrite; (2) bertrandite, milarite, secondary beryl, bazzite, K-feldspar, muscovite-illite, scolecite, gismondine-Ca, analcime, chlorite; and (3) muscovite, albite, quartz, epidote, pumpellyite-(Mg), pumpellyite-(Fe3+), titanite and chlorite. Electron microprobe analyses showed, in addition to major constituents (Si, Ca and Al), minor concentrations (in apfu) of Na (≤0.24), Fe (≤0.10), Mn (≤0.10) and F (≤0.36). The type 1 hydrothermal miarolitic bavenite-bohseite is mostly Al-rich (2.00-0.67 apfu) relative to type 2 proximal bavenite-bohseite and bohseite after beryl, phenakite and helvine-danalite (1.56-0.46, 0.70-0.05, 1.02-0.35 apfu, respectively); and type 3 distal bavenite-bohseite typically after beryl (1.63-0.09 apfu). Raman spectroscopy revealed that the distance between the OH- vibrational modes decreases with increasing bohseite component. The Al content of secondary type 2 proximal bavenite-bohseite is controlled by the composition of the Be precursor whereas type 3 distal bavenite-bohseite with beryl as the Be precursor is more variable and the composition is governed mainly by the composition of fluids. Calcium, a crucial component for bavenite-bohseite origins, was derived from residual pegmatite fluids (Vlastějovice, Vepice IV or Trebíc Plutons) or external sources (e.g. Drahonín IV, Věžná I or Marsíkov). Primary type 1 hydrothermal bavenite-bohseite from miarolitic pockets might have crystallised at T ≈ 300-400°C and P ≈ 200 MPa, whereas the secondary type 2 and 3 bavenite-bohseite formed at T ≈ 300-100°C and P ≈ 200-20 MPa.

To better understand the transport of Mo and W in granitic melts and the formation mechanism of porphyry ore deposits, we have investigated the diffusivities of Mo and W in granitic melts with 0.04-5.1 wt% H2O at 1000-1600°C and 1 GPa using a diffusion couple approach and a Mo saturation approach with Mo sheet serving as the source. The Mo and W diffusivities obtained from diffusion profiles measured by LA-ICP-MS can be described as: DMo,anhy=10-1.47±0.73 exp[-(387±25)/RT], DW,anhy=10-1.28±1.05 exp[-(396±35)/RT], DMo,2.7wt%H2O=10-5.37±0.52 exp [-(211±18)/RT], DMo,5.1wt%H2O= 10-6.87±0.69 exp[-133±20)/RT], where D is diffusivity in m2/s (with the subscripts denoting water contents and \"anhy\" representing nominally anhydrous melt), R is the gas constant, T is the temperature in K, and the activation energies in the exponential are in kJ/mol. When the influence of H2O is incorporated, Mo diffusivity in granitic melts with <5.1 wt% H2O can be modeled as: log DMo=-(1.94±1.58) - (0.87±0.36)ω - [(19341±2784)-(2312±620)w]/T where w is H2O content in the melt in wt%. The diffusion behavior (low diffusivities, high activation energies, and strong H2O effects) of Mo and W indicates that they exist and diffuse in the melt in the form of hexavalent cations. Their low diffusivities imply that the bulk concentrations of Mo and W in exsolved hydrothermal fluid and those in the melt are probably not in equilibrium. However, because of the large fluid-melt partition coefficients of Mo and W, they can still be enriched in the hydrothermal fluid, although to a lesser extent than equilibrium partitioning would allow. Slow Mo and W diffusion can be a significant rate-limiting step for the formation of porphyry Mo/W deposits.

The Shyok Suture Zone is an oceanic remnant of the Neo-Tethyan ocean sandwiched between the Ladakh Batholiths to the south and Karakoram Batholith to the north. The Tirit granitoids in this suture are dark-coloured, relatively rich in ferromagnesian minerals and range from granodiorite-tonalite to gabbro-diorite in composition. Mafic igneous enclaves are quite common and they are intruded by NW-SE parallel doleritic and aplitic dykes. The Tirit granitoids have a wide range of major oxide compositions (SiO2 = 52.1-72.11 wt %, TiO2 = 0.21-1.23 wt %, Al2O3 = 11.42-13.52 wt %, MgO = 1.69-10.69 wt % and CaO = 3.24-9.31 wt %) and show calc-alkaline, metaluminous, I-type characteristics, transitional between primitive and mature arc continental plutons. Rare earth elements (REE) show considerable enrichment in light REE (LREE) as compared to the heavy REE (HREE). Late Cretaceous U/Pb dates (74-68 Ma) show that they formed during the pre-collision northward movement of India. The Tirit dykes are only slightly younger and probably part of the same episode.

The solubility of apatite in anatectic melt plays an important role in controlling the trace-element compositions and isotopic signatures of granites. The compositions of glassy melt inclusions and nanogranitoids in migmatites and granulites are compared with the results of experimental studies of apatite solubility to evaluate the factors that influence apatite behavior during prograde suprasolidus metamorphism and investigate the mechanisms of anatexis in the continental crust. The concentration of phosphorus in glassy melt inclusions and rehomogenized nanogranitoids suggests a strong control of melt aluminosity on apatite solubility in peraluminous granites, which is consistent with existing experimental studies. However, measured concentrations of phosphorus in melt inclusions and nanogranitoids are generally inconsistent with the concentrations expected from apatite solubility expressions based on experimental studies. Using currently available nanogranitoids and glassy melt inclusion compositions, we identify two main groups of inclusions: those trapped at lower temperature and showing the highest measured phosphorus concentrations, and melt inclusions trapped at the highest temperatures having the lowest phosphorus concentrations. The strong inconsistency between measured and experimentally predicted P concentrations in higher temperature samples may relate to apatite exhaustion during the production of large amounts of peraluminous melt at high temperatures. The inconsistency between measured and predicted phosphorus concentrations for the lower-temperature inclusions, however, cannot be explained by problems with the electron microprobe analyses of rehomogenized nanogranitoids and glassy melt inclusions, sequestration of phosphorus in major minerals and/or monazite, shielding or exhaustion of apatite during high-temperature metamorphism, and apatite-melt disequilibrium. The unsuitability of the currently available solubility equations is probably the main cause for the discrepancy between the measured concentrations of phosphorus in nanogranites and those predicted from current apatite solubility expressions. Syn-entrapment processes such as the generation of diffusive boundary layers at the mineral-melt interface may also be responsible for concentrations of P in nanogranitoids and glassy melt inclusions that are higher than those predicted in apatite-saturated melt.

Daqingshan is located in the northwestern North China Craton where late Neoarchaean supracrustal rocks occur widely, but where magmatic zircon ages have rarely been reported for plutonic rocks. In this study, we report SIMS U–Pb zircon ages and Hf isotope, whole-rock element and Nd isotope compositions for 12 magmatic samples, including TTG, quartz monzonitic and monzogranitic gneisses, and meta-gabbroic and dioritic rocks. They have magmatic zircon ages of 2530–2469 Ma; some samples have ages of <2.48 Ga likely influenced by late Palaeoproterozoic tectonothermal events, making their ages less reliable. TTG gneisses have low Sr/Y and La/Yb ratios, with whole-rock ϵNd(t) and in situ magmatic zircon ϵHf(t) values of +1.2 to +2.4 and −1.1 to +6.2, respectively. Quartz monzonite and monzogranite gneisses and gabbroic to dioritic rocks have similar Nd–Hf isotope compositions to the TTG gneisses. The absence of zircon >2.6 Ga in the early Precambrian rocks suggests that the Sanggan Group may have formed in an oceanic environment, whereas the TTG rocks formed as a result of partial melting of the basaltic rocks of the Sanggan Group under relatively low-pressure conditions. Combined with previous studies, the main conclusions are that in the Daqingshan area, late Neoarchaean magmatism was widespread, the late Mesoarchaean – early Neoarchaean was an important period of juvenile continental crustal growth, and the late Neoarchaean supracrustal and plutonic rocks most likely formed in an arc environment. These are common signatures for Neoarchaean crustal evolution throughout much of the North China Craton, and also globally.

Black tourmalines from seven granitic pegmatites (Golodnaya, Kazennitsa, Mokrusha, Kopi Mora, Zheltyye Yamy, Buzheninov Bor and Ministerskaya) related to the Murzinka pluton, Central Urals, Russia have been investigated using electron microprobe analysis, LA-ICP-MS, Raman and Mössbauer spectroscopy. Pegmatites are hosted by serpentinites and gneisses and are classified as schorl, oxy-schorl, fluor-schorl, dravite, oxy-dravite, foitite, oxy-foitite and darrellhenryite. The possible compositional evolution of tourmalines from the Ural pegmatites is as follows: Mg-rich dravite through to Fe-rich schorl, foitite and oxy-foitite to Fe- and Mn-rich darrellhenryite. The major substitutions in the tourmalines are: (1) Fe2+ ⇌ Mg; (2) Al + WO2- ⇌ Fe2+ + WOH-; (3) X-site vacancy + Al ⇌ Na + Fe2+; (4) Al + WO2- ⇌ Mg + WOH-; (5) X-site vacancy + Al ⇌ Na + Mg; and (6) Fe ⇌ Mn. Statistical processing of the trace- and major-element composition distinguished three tourmaline groups: (1) trace Co, Ni, Pb, and major Ca and Mg; (2) uni-, di- and trivalent traces (Li, Zn, Ga) and di- and trivalent majors (Al, Mn); (3) U, Th, Hf, Ta, Nb, Y, In, and Sn which correspond to tri-, tetra-, and pentavalent high-field-strength elements. Mössbauer data shows the Fe3+/Fe2+ ratios in tourmalines from pegmatites hosted by gneisses (0.05-0.18) and serpentinites (0.28-0.65), indicates different oxidising environments. Raman data are consistent with the composition of the tourmalines.

The study presents detailed petrographical, geophysical, structural and geochemical data of the internal nappes zone to establish the deformational history, origin and tectonic setting and constrain the crustal growth and evolution of the active margin of the Dahomeyide belt. Two main lithological units, (i) deformed meta-granitoids (migmatites and gneisses) and (ii) undeformed granitoids, dominate the internal nappes zone. The granitoids are generally I-type, metaluminous to weakly peraluminous, low-K tholeiite to high-K calc-alkaline and of tonalite, granodiorite and granite affinity. The overall trace element patterns of the studied granitoids characterized by the enriched LILE and depleted HFS, with negative peaks of Nb-Ta, Sr, P and Ti, are indications of arc-related magmatism. Structural analysis reveals four deformation phases (D1-D4). D1 represents Northwest-Southeast (NW-SE) Pan African shortening associated with a continent-continent collision, resulting in westward nappe stacking. Progressive NW-SE shortening resulted in D2 and D3 top-to-the-NW dextral and sinistral thrusting events during the Pan-African orogeny. D4 is an extensional event likely associated with the orogenic collapse phase. The gneisses and migmatites, with dominant axial planar foliations, point to their formation in a collisional setting or influence by the Pan-African collisional processes. Continental-arc signatures in these rocks imply continental subduction during their protolith formation. The intrusive granitoid and pegmatite are undeformed, meaning late- to post-orogenic emplacement. These findings suggest that the internal nappes zone archived the subduction-collision and post-collisional phase of the Pan-African orogeny and recorded large-scale migmatization and granitoid emplacement due to partial melting of thickened lower crust between Mid-Cryogenian and late Ediacaran.

Lunar silicic rocks were first identified by granitic fragments found in samples brought to Earth by the Apollo missions, followed by the discovery of silicic domes on the lunar surface through remote sensing. Although these silicic lithologies are thought to make up a small portion of the lunar crust, their presence indicates that lunar crustal evolution is more complex than originally thought. Models currently used to describe the formation of silicic lithologies on the Moon include in situ differentiation of a magma, magma differentiation with silicate liquid immiscibility, and partial melting of the crust. This study focuses on testing a crustal melting model through partial melting experiments on compositions representing lithologies spatially associated with the silicic domes. The experiments were guided by the results of modeling melting temperatures and residual melt compositions of possible protoliths for lunar silicic rocks using the thermodynamic modeling software, rhyolite-MELTS. Rhyolite-MELTS simulations predict liquidus temperatures of 950-1040 °C for lunar granites under anhydrous conditions, which guided the temperature range for the experiments. Monzogabbro, alkali gabbronorite, and KREEP basalt were identified as potential protoliths due to their ages, locations on the Moon (i.e., located near observed silicic domes), chemically evolved compositions, and the results from rhyolite-MELTS modeling. Partial melting experiments, using mixtures of reagent grade oxide powders representing bulk rock compositions of these rock types, were carried out at atmospheric pressure over the temperature range of 900-1100 °C. Because all lunar granite samples and remotely sensed domes have an elevated abundance of Th, some of the mixtures were doped with Th to observe its partitioning behavior. Run products show that at temperatures of 1050 and 1100 °C, melts of the three protoliths are not silicic in nature (i.e., they have <63 wt% SiO2). By 1000 °C, melts of both monzogabbro and alkali gabbronorite approach the composition of granite, but are also characterized by immiscible Si-rich and Fe-rich liquids. Furthermore, Th strongly partitions into the Fe-rich, and not the Si-rich glass in all experimental runs. Our work provides important constraints on the mechanism of silicic melt formation on the Moon. The observed high-Th content of lunar granite is difficult to explain by silicate liquid immiscibility, because through this process, Th is not fractionated into the Si-rich phase. Results of our experiments and modeling suggests that silicic lunar rocks could be produced from monzogabbro and alkali gabbronorite protoliths by partial melting at T < 1000 °C. Additionally, we speculate that at higher pressures (P ≥ 0.005 GPa), the observed immiscibility in the partial melting experiments would be suppressed.

The Tso Morari Crystalline complex (TMCC) of eastern Ladakh, India, is part of the north Indian continental margin and is characterized by eclogitic enclaves embedded within ortho- and paragneisses known as the Puga Gneiss. Two fault zones bound the TMCC: the Karzok fault to the southwest and the Zildat fault to the northeast. In the present study, we carried out Electron Backscatter Diffraction study of quartz of 10 samples collected from the Puga Gneiss. The relict and recrystallized quartz grains were treated separately to understand the deformation conditions of the Puga Gneiss during early and late deformation stages related to UHP metamorphism and final stage of exhumation during retrogression, respectively. Microstructural observations suggest dynamic recrystallization in quartz and plagioclase at different temperature ranges. Misorientation analysis of both relict and recrystallized quartz grains reveals presence of Dauphiné Twins. Lattice preferred Orientation (LPO) of axis of relict quartz grains generally shows more than one point maxima indicating that the relict grains preserve LPO developed during different stages of metamorphism/deformation. On the other hand, LPO of axis of recrystallized grains from Karzok and Zildat fault zones shows asymmetric single girdle either normal or at an angle to the foliation plane, which suggests simple shear. We conclude that grain size reduction and recrystallization of the Puga Gneiss was greatly influenced by Dauphiné Twin and the final exhumation of the TMCC took place in a simple shear environment aided by activity along its two binding fault zones.

The relationship between magmatism and gold mineralization has been a topic of interest in understanding the formation of ore deposits. The Baizhangzi gold deposit, located in the northern margin of the North China Craton, is hosted by the Baizhangzi granite (BZG) and provides a case to evaluate the relation between granite and gold mineralization in Late Triassic. In this study, we present petrography, bulk geochemistry, zircon U-Pb isotope and trace elements data, as well as major elements of biotite and plagioclase for the BZG to evaluate the petrogenesis and link with gold mineralization. The BZG comprises biotite monzogranite, biotite-bearing monzogranite and monzogranite (BZGs). Zircon U-Pb geochronology shows that all the granitoids of BZGs were coeval with a formation age of 232 Ma. The granitoids, with high SiO2, Al2O3 and Sr, while low Y and Yb, show adakitic affinity. They are enriched in LILFs (e.g., Rb, Ba, Th, U and Sr) and LREEs, while depletion in HFSEs (e.g., Nb, Ta, P and Ti). The geochemical and mineral chemical data suggest that the granitoids have experienced the fractional crystallization of biotite + plagioclase + K- feldspar + apatite. Crystallization temperature is estimated as ca. 700°C, and pressure is between 0.71 kbar and 1.60 kbar. The monzogranite shows higher values of logfO2, △FMQ and △NNO than the biotite-bearing monzogranite, ranging from −19.76 to −11.71, −4.93 to +3.67 and −5.48 to +3.11, respectively. The fractional crystallization, together with high fO2, K-metasomatism and low evolution degree, provided favourable conditions for gold mineralization.