Multi-stage crustal melting from Late Permian back-arc extension through Middle Triassic continental collision to Late Triassic post-collisional extension in the East Kunlun Orogen

The East Kunlun Orogen is an important part of the East Tethys region and has received significant attention with regards to the evolution of the Tethys Ocean. This contribution presents geochronological,whole-rockmajor and trace element geochemical, and Sr-Nd-Hf isotopic data of magmatic rocks within the Kengdenongshe polymetallic deposit in the eastern part of the East Kunlun Orogen. Here, we report zircon U\\Pb ages of ca. 257 Ma and ca. 211 Ma for granite porphyry intrusions, and ca. 240Ma for the rhyolitic tuff. These rocks are characterized by high SiO₂, variable Al₂O₃ and K₂O, lowNa2O, MgO and CaO contents, and high A/CNK ratios,which is typical of S-type granitic rocks. They exhibit large-ion lithophile element enrichment, depletion of high field strength elements, have low (La/Yb)N ratios, and negative εNd anomalies. They also display variable (⁸⁷Sr/⁸⁶Sr)i ratios (0.709981 to 0.720907), negative εNd (t) values (−8.7 to −5.5), and a wide (enriched) zircon εHf (t) range (−10.1 to −0.8). The geochemical and isotope data indicate magma derivation through dehydration melting of heterogeneous crustal sources including clay-poor meta-sedimentary rocks and amphibolite, which are both parts of the East Kunlun Orogen basement. These results provide evidence for the evolution of the Paleo-Tethys Ocean in the East Kunlun Orogen including Late Permian (266–255 Ma) back-arc extension, Late Permian to Middle Triassic (255–240 Ma) subduction, Middle Triassic (240–225 Ma) continental collision, and Late Triassic (b 225 Ma) post-collisional extension. This study further suggests that the 257 Ma and 211 Ma granite porphyries are related to the asthenosphere upwelling in a back-arc basin and post-collision extensional setting, respectively. The 240 Ma rhyolitic tuff is linked to anatexis associated with crustal thickening during continental collision

Multiple sources of the Early Mesozoic Gouli batholith, Eastern Kunlun Orogenic Belt, northern Tibetan Plateau: Linking continental crustal growth with oceanic subduction

Orogenic belts have been among the most important locations to investigate the growth of continental crust (CC). The Eastern Kunlun Orogenic Belt (EKOB), which contains widespread Permian–Triassic granitoids, is volumetrically comparable to the Cenozoic Gangdese magmatic belt in the Tibetan Plateau and is an ideal region to investigate the mechanism of the Paleozoic–Mesozoic CC growth in this region. The Gouli batholith at the eastern end of the EKOB consists of the synchronous Xiangride granodiorite, Asiha quartz diorite (ca. 242 Ma) and adamellite. The granodiorite and quartz diorite, both of which contain magmatic enclaves, show medium–high K, calc-alkalic and metaluminous signatures and have similar rare earth element and trace element patterns to those of bulk CC. Besides, the Xiangride granodiorite displays distinct adakitic signatures (average Sr/Y of 47). The Sr-Nd isotopic values for the different types of rocks are roughly similar ((87Sr/86Sr)i = 0.708167–0.713553, εNd(t) = − 6.8 to − 5.3), while Hf isotopes are distinguishable, with εHf(t)granodiorite = 0.3 to 5.1 and εHf(t)diorite = − 1.6 to 0.7. These geochemical and petrographic signatures suggest that the granodiorite originated from the partial melting of subducting oceanic crust and terrigenous sediments, and the quartz diorite and enclaves formed via the mixing of slab-derived magma and enriched mantle-derived melt. Further comprehensive analyses of the spatial and temporal distribution of regional magmatic rocks, metamorphism and sedimentary facies reveal that the Gouli batholith and most of the Permian–Triassic granitoids in the EKOB formed during the subduction of the Paleo-Tethys Ocean instead of subsequent syn-collision setting. Thus, we contend that the Permian–Triassic CC growth of the EKOB occurred in a slab subduction setting and that both oceanic slab and subcontinental mantle significantly contributed to this process

Noble gases in pyrites from the Guocheng-Liaoshang gold belt in the Jiaodong province: evidence for a mantle source of gold

The recent mineral exploration programme (2009–2014) in the Jiaodong gold province identified the new Guocheng-Liaoshang gold metallogenic belt which contains reserves of 92 tonnes (t) Au. In the main deposits the ore is fault-hosted in massive sulfides that make up to 25 to 95 vol%. The He-Ar isotope compositions of ore-forming fluids from 20 pyrite samples from the five main deposits are reported here. 3He/4He range between 0.41 and 2.39 Ra, 40Ar/36Ar are 367 to 2112 and 40Ar⁎/4He are 0.40–3.78. The data require four gas sources; a dominant mantle-derived component plus sub-ordinate crustal radiogenic, meteoric and basin brine components. The mantle end-member has 3He/4He (3.32–4.00 Ra). This is lower than most estimates for sub-continental lithospheric mantle (SCLM: 6–7 Ra), implying that it was probably refertilized by subduction-related fluid metasomatism. This is consistent with He-Ar isotopes reported for SCLM xenoliths from basalts in the Shandong Province. Within the mineralisation province, the mine Au reserve is positively correlated with the proportion of mantle-derived He in the ore-forming fluids. This implies that the fluids, and by inference the gold, was largely derived from mantle melts during lithospheric extension. Given the conspicuous association of gold ore deposits with mantle-derived magma in the Jiaodong Peninsula, we envisage that our genetic model can be applied, to some extent, to evaluate the potential of some mineral exploration targets

Notch-dependent control of myelopoiesis is regulated by fucosylation

Cell-cell contact–dependent mechanisms that modulate proliferation and/or differentiation in the context of hematopoiesis include mechanisms characteristic of the interactions between members of the Notch family of signal transduction molecules and their ligands. Whereas Notch family members and their ligands clearly modulate T lymphopoietic decisions, evidence for their participation in modulating myelopoiesis is much less clear, and roles for posttranslational control of Notch-dependent signal transduction in myelopoiesis are unexplored. We report here that a myeloproliferative phenotype in FX−/− mice, which are conditionally deficient in cellular fucosylation, is consequent to loss of Notch-dependent signal transduction on myeloid progenitor cells. In the context of a wild-type fucosylation phenotype, we find that the Notch ligands suppress myeloid differentiation of progenitor cells and enhance expression of Notch target genes. By contrast, fucosylation-deficient myeloid progenitors are insensitive to the suppressive effects of Notch ligands on myelopoiesis, do not transcribe Notch1 target genes when cocultured with Notch ligands, and have lost the wild-type Notch ligand-binding phenotype. Considered together, these observations indicate that Notch-dependent signaling controls myelopoiesis in vivo and in vitro and identifies a requirement for Notch fucosylation in the expression of Notch ligand binding activity and Notch signaling efficiency in myeloid progenitors