Lithium enrichment of the magmatic-hydrothermal fluid in albite-spodumene pegmatite from Lijiagou, Eastern Tibetan Plateau: Evidence from fluid inclusions

Albite-spodumene pegmatites, which are remarkable resources of Li worldwide, may experience both magmatic-hydrothermal transition and sub-solidus hydrothermal alteration during their formation and evolution. However, fluids involved in the different stages of the evolution of a spodumene-bearing pegmatitic systems are not well defined, especially at the magmatic-hydrothermal transition stage. In the Lijiagou deposit, western Sichuan Province, fluid inclusions of a typical albite-spodumene pegmatite were studied to determine the degree of magmatic-hydrothermal fluid Li enrichment and the potential for lithium mineral crystallization at the magmatic-hydrothermal transition stage. Micro-petrographic analyses identified different types of fluid inclusions of either primary, pseudo-secondary or secondary origin and inclusions containing devitrified silicate glass. The presence of these inclusions suggests that the pegmatite underwent both the magmatic-hydrothermal transition stage and a post-crystallization hydrothermal process over its evolution. The results of fluid inclusion LA-ICP-MS analyses show that the aqueous ± carbonic fluids represented by the pseudo-secondary type 1a and 1b inclusions carry significant amount of Li, with Na and Li predominating the cation budget of these pegmatitic fluids. The aqueous ± carbonic fluids exhibit typical magmatic-hydrothermal fluid compositional characteristics and exhibit high abundance of Li in this pegmatitic system at the magmatic-hydrothermal transition stage. The relative abundance of Li to Na and K lies within the uppermost range of those reported from lithium-cesium-tantalum pegmatite systems. This is consistent with the elevated incorporation of Li in pegmatitic quartz from the albite-spodumene pegmatite. The compositional characteristics of the fluids at the magmatic-hydrothermal transition stage may be used to imply the Li mineralization potential of the pegmatitic system

An experimental investigation into the partition of Mo between aqueous fluids and felsic melts: Implications for the genesis of porphyry Mo ore deposits

International audienceMost of the world’s large molybdenum (Mo) deposits are genetically related to magmas that underwent significant fractional crystallization and fluid exsolution, and the residual silicate melts are commonly peralkaline. To understand the relationship between melt compositions and the genesis of porphyry Mo mineralization, the partition coefficients of molybdenum (DMo) between fluid and felsic melt were determined at 850 °C, 900 °C, and 100 MPa with various values of A/NK [molar Al2O3/ (Na2O + K2O) in the melt] under an oxygen fugacity around the Ni–NiO (NNO) buffer. The results show that DMo decreases from 4.23 to 0.4 with increasing A/NK from 0.75 to 1.36 in the carbon dioxide series (fluid composed of = 0.096 [molar CO2/ (CO2 + H2O)] and 17.5 wt.% NaCl). A similar trend was observed in pure water, with A/NK varying from 0.72 to 1.23, DMo decreases from 0.54 to 0.15. Significantly, DMo in peralkaline melt is consistently higher than that in peraluminous melt, even with the same NBO/T (the ratio of non-bridge oxygen and tetrahedron ion). Our study therefore reveals that Mo is easily distributed into fluids that exsolved from peralkaline magmas. This finding explains why highly fractionated magmas are critical for porphyry Mo mineralization

Crystallisation conditions (T, P, f O2) from mineral chemistry of Cu- and Au-mineralised alkaline intrusions in the Red River-Jinshajiang alkaline igneous belt, western Yunnan Province, China

The Oligocene Yao-an syenite porphyry, associated with gold mineralisation, and the Machangqing alkali granite porphyry-monzonite porphyry, associated with Cu mineralisation, belong to the Red River-Jinshajiang alkaline igneous belt that formed in a continental setting in southwestern China. A study of the mineral chemistry of major silicate minerals in these two mineralised intrusions provides insights into their overall crystallisation conditions. The temperature and pressure conditions, derived from amphibole-plagioclase and perthite-plagioclase geothermometry and Al-in-amphibole barometry, suggest that the Yao-an intrusion crystallised at around 820 ± 50°C and 0.9-1.3 kbar, whereas the Machangqing intrusion crystallised at around 730 ± 50°C and 2.2-2.8 kbar. The higher temperature and lower pressure of crystallisation for the Yao-an intrusion relative to the Machangqing intrusion indicates that it was emplaced at a shallower crustal level. Based on biotite composition, the two intrusions formed under imposed oxygen fugacities above the Ni-NiO buffer (NNO), and the Yao-an intrusion crystallised under more oxidising conditions than the Machangqing intrusion. The results show that the intrusions associated with Cu-Au mineralisation in the Red River-Jinshajiang alkaline igneous belt were emplaced at a relatively high fO2, which, together with the weakly fractionated magma, favoured Au enrichment relative to Cu in the belt

Epigenetic Activation of WNT5A Drives Glioblastoma Stem Cell Differentiation and Invasive Growth

Glioblastoma stem cells (GSCs) are implicated in tumor neovascularization, invasiveness, and therapeutic resistance. To illuminate mechanisms governing these hallmark features, we developed a de novo glioblastoma multiforme (GBM) model derived from immortalized human neural stem/progenitor cells (hNSCs) to enable precise system-level comparisons of pre-malignant and oncogene-induced malignant states of NSCs. Integrated transcriptomic and epigenomic analyses uncovered a PAX6/DLX5 transcriptional program driving WNT5A-mediated GSC differentiation into endothelial-like cells (GdECs). GdECs recruit existing endothelial cells to promote peritumoral satellite lesions, which serve as a niche supporting the growth of invasive glioma cells away from the primary tumor. Clinical data reveal higher WNT5A and GdECs expression in peritumoral and recurrent GBMs relative to matched intratumoral and primary GBMs, respectively, supporting WNT5A-mediated GSC differentiation and invasive growth in disease recurrence. Thus, the PAX6/DLX5-WNT5A axis governs the diffuse spread of glioma cells throughout the brain parenchyma, contributing to the lethality of GBM