The debate of hydrous and anhydrous mafic magmatism in the Emeishan large igneous province (ELIP) requires more robust petrological and mineralogical evidence. This paper reports zircon U–Pb ages, clinopyroxene and hornblende major element compositions, whole-rock geochemical and Sr–Nd–Pb isotopic data of hornblende-rich mafic plutonic rocks from the Xinhe igneous complex in the central ELIP to address this issue. Analytical results indicate that the Xinhe mafic rocks were emplaced at 260–259 Ma, consistent with the main eruptive phase of the ELIP. The Xinhe mafic rocks can be divided into hornblende gabbro and gabbroic diorite based on petrographic characteristics and MgO content. The Sr–Nd–Pb isotopic signatures of Xinhe mafic rocks are indicative of an EMI-type enriched mantle source, which is similar to the adjacent contemporaneous Miyi layered intrusions and basalts in the ELIP. The Xinhe mafic rocks exhibit a hydrous-type crystallization sequence (clinopyroxene–hornblende+plagioclase), which contrasts markedly with the anhydrous-like olivine+plagioclase–clinopyroxene sequence documented in the Miyi layered intrusions. This difference records contrasting magmatic water conditions during crustal magmatic evolution, although water enrichment during differentiation, differing pressure–redox histories, and fluid interaction may also contribute to the observed assemblages. Mantle-source water heterogeneity remains a plausible interpretation that requires independent confirmation.
The Yidun Terrane, located in the eastern Sanjiang Tethys domain of southwestern China, records extensive Late Cretaceous magmatism, yet its geodynamic setting remains controversial. Zircon U–Pb dating yields a crystallization age of 103.37 ± 0.51 Ma. The rocks are characterized by high SiO2 contents (73.9–78.9 wt.%), ferroan compositions, predominantly high-K calc-alkaline and weakly peraluminous affinities, elevated 10,000 × Ga/Al values (2.81–3.29), and low P2O5 contents (0.03–0.04 wt.%). Integrated mineralogical and whole-rock geochemical evidence indicates an A-type affinity, while incompatible-element geochemical characteristics further suggest an A2 affinity. Their highly evolved compositions and depletion in Eu, Sr, Ba, and P are consistent with substantial fractional crystallization, although source composition and melting conditions may also have contributed to these features. Zircon εHf(t) values range from −1.1 to +0.5, with two-stage Hf model ages of 1.14–1.24 Ga, whereas whole-rock εNd(t) values range from −5.2 to −4.9, with two-stage Nd model ages of 1.30–1.32 Ga, indicating that the magma was derived predominantly from Mesoproterozoic crust with only limited juvenile input. Regional comparisons reveal substantial spatial differences among the Late Cretaceous plutons, but the available dataset is insufficient to establish a continuously sampled north–south evolutionary trend. Overall, the Queershan pluton most likely formed in a post-collisional extensional setting following the Lhasa–Qiangtang collision, and this process may have been further enhanced by slab break-off of the Bangong–Nujiang Ocean. In contrast, the younger magmatism in the southern Yidun Terrane is more readily reconciled with rollback-related back-arc extension associated with continued northward subduction of the Yarlung Zangbo Neo-Tethys.
Marine–continental transitional shales contain highly heterogeneous pore systems whose structural characteristics vary across multiple pore-size scales. However, how multifractal characteristics differ among macropores, mesopores, and micropores within a unified full-scale pore size distribution (PSD), and whether their geological associations vary with pore scale, remain poorly constrained in marine–continental transitional shale. Nine shale core samples from the First Member of the Benxi Formation (Ben1 Member) in the southeastern Ordos Basin, China, were investigated using total organic carbon (TOC), vitrinite reflectance (Ro), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-pressure mercury intrusion (HPMI), low-temperature N2 adsorption (LTNA), and low-temperature CO2 adsorption (LTCA). A full-scale PSD was reconstructed by integrating HPMI, LTNA, and LTCA data, and multifractal analysis was performed separately for macropores, mesopores, and micropores. The results show the following: (1) The Ben1 Member shale is overmature and clay-rich, and FE-SEM observations identify clay-mineral intercrystalline pores, organic pores, and organic-matter shrinkage fractures as representative pore and fracture types. (2) All three pore-size classes exhibit pronounced multifractal behavior but show distinct scale-dependent characteristics. Macropores and mesopores have relatively high Hurst exponents (H) and small multifractal-spectrum widths (Δα), whereas micropores show significantly lower H and higher Δα, indicating stronger heterogeneity. (3) Exploratory analyses revealed distinct scale-dependent covariation patterns: macropore multifractal characteristics were associated mainly with pore size and TOC, mesopore characteristics with pore volume and surface development, and micropore characteristics with TOC and clay content. None of these highlighted scale-dependent associations remained statistically significant after Benjamini–Hochberg correction, and the key macropore associations were sensitive to individual samples in leave-one-out analysis. These scale-dependent patterns are therefore interpreted as hypothesis-generating rather than causal relationships. The results provide a case-specific characterization of scale-dependent pore heterogeneity in the Ben1 Member shale and a basis for comparison with other marine–continental transitional shale systems.
Selective lithium recovery from dilute brines remains challenging because Li+ must be separated from competing ions, particularly Mg2+. In this work, a commercial NF90 nanofiltration membrane was used as a non-dispersive interface between a simulated brine and the hydrophobic ionic liquid [P6,6,6,14][PHOS]. Individual-salt experiments yielded apparent overall mass transfer coefficients of 638 ± 273, 100.5 ± 19.8, and 10.1 ± 0.7 L m−2 h−1 for Na+, Li+, and Mg2+, respectively. Replacing water with 10% (v/v) [P6,6,6,14][PHOS] in hexane as the receiving phase increased Li extraction from 18.6 ± 3.0% to 40.9 ± 2.0%. Under direct Li+/Mg2+ competition, selectivities of 2.19 ± 1.10 and 3.83 ± 0.56 were obtained with the diluted and neat ionic liquid receiving phases, respectively. With neat [P6,6,6,14][PHOS], Li extraction reached 40.3%, and 6.0% of the extracted Li was subsequently recovered in pure water under non-optimized conditions. CHNS analysis showed no detectable transfer of organic material derived from the ionic liquid to the aqueous feed. Overall, NF90 was the main source of Li+/Mg2+ transport discrimination, whereas [P6,6,6,14][PHOS] mainly increased Li uptake.
Lithofacies and pore structure strongly influence shale reservoir quality and shale gas enrichment. To characterize pore development in the Lower Cambrian Shuijingtuo Formation shale of the Middle Yangtze region, core samples from well EYY1 were analyzed using total organic carbon (TOC) measurements, whole-rock X-ray diffraction (XRD), optical microscopy, field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), and nuclear magnetic resonance (NMR). The results show that: (1) Four mineralogical lithofacies were identified, including carbonate mudstone (CM), mixed mudstone (MM), argillaceous mudstone (AM), and siliceous mudstone (SM). The studied interval is dominated by SM, MM, and CM, whereas AM is rare. SM has the highest TOC content, followed by MM and CM. (2) The pore systems are dominated by micropores and small pores, with the main pore-size peaks concentrated at approximately 10–30 nm. SM has the highest porosity and the most pronounced organic-pore development. MM contains diverse pore types, including intergranular pores, intragranular clay-mineral pores, microfractures, and minor organic-related pores, whereas CM is mainly characterized by carbonate-related dissolution pores and microfractures. (3) Pore development is jointly controlled by TOC content, mineral composition, and lithofacies framework. SM represents the most favorable reservoir lithofacies, while MM also exhibits considerable reservoir potential. These results indicate that shale gas evaluation of the Shuijingtuo Formation should integrate TOC content, lithofacies, mineral composition, and pore-development characteristics.
