Obtaining and plasma-electrolyte modification of fibers of ultralight magnesium alloy

The results of researches for the transformation to fiber state the Mg-8Li-1Al-0.6Ce-0.3Y ultralight magnesium alloy by the Pendant Drop Melt Extraction (PDME), and subsequent modifying obtained fibers by Plasma-Electrolytic Treatment (PET) are presented. The results demonstrate possibility of successful application of the above-mentioned methods in relation to chemically active materials. Purposeful modifying of ultralight magnesium alloys by PDME and PET methods is capable to significantly expand areas of using to these materials.

Supplemental Material: Identifying crystal accumulation and melt extraction during formation of high-silica granite

Analytical methods, modeling setup for magmatic evolution, and data.

Nb–Ta Behaviour during Magma-to-Pegmatite Transformation Process: Record from Zircon Megacrysts in Pegmatite

Due to the absence of early magma records in pegmatites, it is difficult to investigate the behavior of Nb and Ta during the transformation from magma to pegmatite melt. Zircon megacrysts in an NYF-type (Nb-Y-HREE-F) pegmatite from the Arabian Shield could be divided into three phases from core to margin. The Phase Ι zircon in the core of the zircon megacrysts had typical magma oscillatory zonation with ∑REE content from 300 to 400 ppm, Th/U ratios of less than 0.1 and Nb/Ta ratios of less than 1.0. Phase ΙΙ zircon had oscillatory zonation and was enriched with LREEs mostly with Th/U ratios of 0.1–0.2 and Nb/Ta ratios of 1.0–3.0. Phase ΙΙΙ unzoned zircon had the highest ∑REE content, from 8000 to 15,000 ppm, with Th/U ratios higher than 3.0 and Nb/Ta ratios higher than 5.0. The Hf-O isotopic composition was similar in the different phases of zircon with initial 176Hf/177Hf ratios of 0.28258–0.28277, εHf(t) values from 8.0 to 12.0 and δ18OVSMOW from +4.0‰ to +5.0‰. Zircon megacrysts in the NYF-type pegmatite from the Arabian Shield record the transformation from magma to pegmatite melt. Similar Hf-O isotopic compositions mean a closed magmatic system without contamination by external melt, rock or fluid. The proposed modeling shows that magma with low Nb and Ta concentrations and Nb/Ta ratios could evolve into residual pegmatite melt with a high Nb content and superchondrite Nb/Ta ratio during several stages of melt extraction and fractional crystallization of Ti-rich minerals, such as rutile and titanite. The Nb/Ta ratio can be used as an effective indicator of the transformation process from magma to pegmatite melt.

Supplemental Material: Identifying crystal accumulation and melt extraction during formation of high-silica granite

Analytical methods, modeling setup for magmatic evolution, and data.

Supplemental Material: Identifying crystal accumulation and melt extraction during formation of high-silica granite

Analytical methods, modeling setup for magmatic evolution, and data.

A model involving amphibolite lower crust melting and subsequent melt extraction for leucogranite generation

In the southern Tibetan Plateau, leucogranites are dominantly distributed in the Himalayan orogenic belt with minor occurrences in the southern Lhasa subterrane. In this paper, we report the first Miocene Anglonggangri leucogranites in the northern Lhasa subterrane. This finding provides important constraints on both leucogranite petrogenesis and the tectono-magmatic evolution of the Lhasa terrane. The Anglonggangri leucogranites include biotite-muscovite granite and slightly younger garnet-muscovite granite and pegmatite. Zircon U-Pb and muscovite 40Ar-39Ar dating of these leucogranites yields Miocene ages of 11.1−10.2 Ma. The biotite-muscovite and garnet-muscovite granites are characterized by high SiO2 (72.3−74.4 wt%) and Al2O3 contents (14.4−15.4 wt%) and are peraluminous. The biotite-muscovite granite displays geochemical signatures with high Sr/Y (29.2−81.0) and (La/Yb)N (37.5−98.9) ratios, low Y (4.30−7.22 ppm) and Yb contents (0.26−0.47 ppm), low to moderate initial (87Sr/86Sr)i ratios (0.7085−0.7192), and moderate εNd(t) values (−10.17 to −6.94). Furthermore, they also exhibit radiogenic Pb isotope and variable zircon εHf(t) values (−9.6 to +4.4) with Proterozoic Nd (1.1−1.4 Ga) and Hf model ages (0.8−1.7 Ga). By comparison, the garnet-muscovite granite has lower CaO, MgO, TiO2, and total FeO contents and is enriched in Rb (380−466 ppm) and depleted in Sr (24.1−38.5 ppm) and Ba (30.7−58.6 ppm) and further characterized by a significant rare earth element (REE) tetrad effect and non-charge and radius-controlled (CHARAC) trace element behaviors. The garnet-muscovite granite shows a negative Eu anomaly and positive correlations among Sr and Eu, Sr and Ba, and Th and light rare earth elements (LREEs). Pegmatite comprising Nb-Ta oxides and cassiterite occurs in the garnet-muscovite granite. Geochronological and geochemical characteristics of the Anglonggangri leucogranites indicate that the magma of the biotite-muscovite granite was derived from partial melting of amphibolite lower crust contaminated with Proterozoic-Archean upper crustal materials. The garnet-muscovite granite was generated through melt extraction from the biotite-muscovite granite crystal mush. These results confirm that partial melting of the amphibolite lower crust not only occurred in the southern and central Lhasa subterranes but also in the northern Lhasa subterrane.

Arc-related peridotite blocks exhumed to the Eastern Block of the North China Craton prior to 2.47 Ga

The Songling and Majiayu peridotite blocks occur in the Eastern Block, North China Craton (NCC). Geothermobarometry data show that the Songling peridotites began exhumation from a depth of c. 70 km (c. 23 kbar). During exhumation, the Songling peridotites were intruded by an upper-crust-derived, high-δ18O (up to +7.28‰ in zircon) trondhjemitic dyke at 2.47 Ga and experienced granulite-facies metamorphism. The Songling peridotites have hybrid mantle wedge (HMW) -like high SiO2 (> 45 wt%), high FeOt (c. 10 wt%) content, high modal orthopyroxene abundance (> 35%) and high ϵNd(t) (+18.4 to +21.4), which were generated by the reaction between peridotite and eclogite-derived melts. The clinopyroxenes from the Songling peridotites were in equilibrium with a Nb-, Zr- and Ti-depleted arc-like magma. The Majiayu peridotites are characterized by depletion of Nb, Zr and Hf and are highly enriched in FeOt, Th and light rare earth elements (LREEs), which can be interpreted as an open system reaction between hydrous melts and fore-arc mantle peridotites. These two peridotite blocks are considered to be arc-related mantle peridotites that experienced melt extraction and metasomatism in different styles. They were exhumed to the north margin of the North China Craton during the c. 2.47 Ga arc–continent collision along the Zunhua structural belt.

The largest plagiogranite on Earth formed by re-melting of juvenile proto-continental crust

The growth of continental crust through melt extraction from the mantle is a critical component of the chemical evolution of the Earth and the development of plate tectonics. However, the mechanisms involved remain debated. Here, we conduct petrological and geochemical analyses on a large (up to 5000 km2) granitoid body in the Arabian-Nubian shield near El-Shadli, Egypt. We identify these rocks as the largest known plagiogranitic complex on Earth, which shares characteristics such as low potassium, high sodium and flat rare earth element chondrite-normalized patterns with spatially associated gabbroic rocks. The hafnium isotopic compositions of zircon indicate a juvenile source for the magma. However, low zircon δ18O values suggest interaction with hydrothermal fluids. We propose that the El-Shadli plagiogranites were produced by extensive partial melting of juvenile, previously accreted oceanic crust and that this previously overlooked mechanism for the formation of plagiogranite is also responsible for the transformation of juvenile crust into a chemically stratified continental crust.

Supplemental Material: A model involving amphibolite lower crust melting and subsequent melt extraction for leucogranite generation

Table S1: Isotopic data of U-Pb age determinations on zircons of the Anglonggangri biotite-muscovite and garnet-muscovite granites; Table S2: 40Ar-39Ar dating results for muscovite from the pegmatite in the Anglonggangri area; Table S3: Whole-rock major and trace element compositions of the Anglonggangri biotite-muscovite and garnet-muscovite granites; Table S4: Whole-rock Pb isotopic compositions of the Anglonggangri biotite-muscovite and garnet-muscovite granites; Table S5: Zircon in situ Lu-Hf isotopic compositions of the Anglonggangri biotite-muscovite granite; Table S6: Partition coefficients and assumed magma source compositions used in geochemical modeling; Table S7: Partition coefficients and assumed compositions used in geochemical modeling and the calculated results.