Shiwei Song

The magma sources and tectonic significance of Late Triassic Cu-bearing intrusions in the northern Yidun Arc remain less well constrained than those of the southern segment. This study integrates geological observations, zircon U–Pb geochronology and whole-rock geochemistry to investigate the Changdagou granodiorite porphyry. LA-ICP-MS analyses of 23 magmatic zircons yield a weighted mean ²⁰⁶Pb/²³⁸U age of 215.4 ± 0.5 Ma (MSWD = 0.53), constraining Late Triassic crystallization of the Cu-bearing intrusion. The analyzed rocks contain 67.40–68.16 wt.% SiO₂ and exhibit high-K calc-alkaline and weakly peraluminous compositions, with A/CNK values of 1.03–1.14. Their rare earth element patterns show light rare earth element enrichment relative to heavy rare earth elements and negative Eu anomalies (δEu = 0.48–0.68). Primitive mantle-normalized patterns display enrichment in Rb, Th and K and depletion in Nb, Ta, P and Ti. Low Ga/Al ratios and decreasing P₂O₅ contents with increasing SiO₂ support an I-type granitoid affinity. Relatively low Mg^# values (33–36), together with low Nd/Th and Nb/Ta ratios, suggest a substantial crustal contribution to magma generation. Trace-element discrimination results and regional geological relationships support an association with the tectonomagmatic system established by westward subduction of the Ganzi–Litang Ocean. These results complement previous zircon-based investigations by providing whole-rock constraints on the petrogenesis and tectonic affinity of the Changdagou intrusion within the Late Triassic magmatic framework of the northern Yidun Arc.

肃北包来呼都格地区地表广泛出露钨矿化，包括本文首次报道的白钨矿化，以及红尖兵山石英脉型黑钨矿床。该矿床规模达中型以上、是甘肃北山地区代表性的钨矿床之一，其成矿时代存在形成于石炭纪-二叠纪和三叠纪的争论。白钨矿化成因机制和红尖兵山黑钨矿床成矿时代的不明确，严重制约着对该地区钨成矿作用的全面认识、阻碍着该地区的钨矿找矿工作的科学部署、限制着对北山地区钨成矿规律的客观总结。本文通过黑钨矿LA-ICP-MS U-Pb同位素分析，精确限定了红尖兵山钨矿床形成于晚三叠世(约215Ma)；并结合晚三叠世北山地区处于碰撞后伸展的构造背景，以及红尖兵山矿区及外围的成钨流体具有富F、低氧逸度的特征——发育与大量黄玉和(或)萤石、钾长石共生的黑钨矿或贫Mo白钨矿，推断包来呼都格地区的钨成矿作用与壳源高分异S型花岗岩相关的还原型钨矿床类似，具有较大的成矿潜力。鉴于石英大脉型钨矿体在红尖兵山老矿区已大量出露，说明该矿化系统根部已经接近地表，在老矿区继续开展找矿勘探已意义不大。该地区钨矿找矿勘查应当围绕老矿区南部约800m处呈东西向展布长达10余千米的石英脉两侧进行，因为该石英脉内及附近多处发育有后期还原性成矿流体形成的贫钼白钨矿，且碳酸盐岩沿该石英脉具有稳定的出露。一方面，该东西向展布石英脉沿深大断裂出露、该断裂有利于晚三叠世成钨岩浆侵位和(或)成矿流体的迁移；另一方面，沿石英脉稳定分布的碳酸盐岩能提供大量的Ca²⁺，有利于热液流体中的WO₄^2-与Ca²⁺结合，高效地沉淀白钨矿。

超大型矿床的形成往往与多期次成矿作用叠加和(或)脉冲式成矿作用相关。朱溪矽卡岩型钨矿床是全球规模最大的钨矿床，位于江南钨矿带。前人已经厘定了朱溪矿床存在早白垩世成矿作用叠加于晚侏罗世成矿作用的多期成矿；但该矿床是否经历过脉冲式成矿作用并不明确。本研究发现未经历退化蚀变过程的石榴子石矽卡岩直接被脉状石榴子石矽卡岩穿插的现象在朱溪矿床中十分普遍，该现象很可能是岩浆热液流体脉冲式出溶的产物。为此，本文通过对朱溪矿床中两类共存符山石的LA-SF-ICP-MS U-Pb同位素年龄测定，厘定了早阶段自形符山石(Ves1)和充填于早阶段自形符山石-石榴子石颗粒间的他形符山石(Ves2)均为晚侏罗世成矿作用的产物，两者分别形成于155.1±1.5Ma和150.8±3.5Ma。此外，基于两类符山石及与其共生白钨矿原位主微量元素分析，它们具有以下特征：(1)两阶段白钨矿不仅稀土元素配分模式相似，而且均具有高分异岩浆热液流体成因白钨矿所具有的低Sr含量(< 24×10^-6)特征；(2)晚阶段他形符山石相对于早阶段自形符山石，具有显著富集易在富F残余岩浆体系聚集的Nb (Ves1: < 1×10^-6, Ves2: 10×10^-6~14×10^-6)、Ta (Ves1: < 1×10^-6, Ves2: 2×10^-6~3 ×10^-6)含量的特征，但却显著亏损在花岗质岩浆出溶流体时、高度富集于岩浆流体的Li元素(Ves1: 14×10^-6~43×10^-6, Ves2: 1×10^-6~4×10^-6)、Zn (Ves1: 513×10^-6~606×10^-6, Ves2: 138×10^-6~275×10^-6)。这些数据特征共同说明两类共存的不同产状符山石具有相同成因，是由晚侏罗世成矿岩浆脉冲式出溶的岩浆热液流体所形成，与朱溪矿床深度就位的岩浆房经过连续地结晶作用(“二次沸腾”)和(或)富挥发分幔源岩浆注入所引起的脉冲式流体出溶密切相关。脉冲式出溶的岩浆流体形成的两类符山石中白钨矿大量出现，结合退化蚀变在朱溪矿床中仅局部发育的现象，说明退化蚀变并非矽卡岩型钨矿床形成具有经济价值矿体的必要条件。

We present in situ LA-ICP-MS U-Pb dating of xenotime and monazite in assemblages with native gold and Au (Ag) tellurides from the Xiaoqinling lode gold district in central China. Composite xenotime and monazite grains formed through coupled dissolution-reprecipitation reactions reveal two discrete gold mineralization events. The first gold mineralization event, recorded by monazite (158.6 ± 3.3 Ma, Tera-Wasserburg lower intercept age) and xenotime cores (157.11 ± 0.83 Ma, weighted mean 206Pb/238U age), is characterized by the mineral assemblage of lingbaoite (AgTe3)-sylvanite ([Au,Ag]2Te4)-stützite (Ag5–xTe3)/native tellurium-sylvanite-stützite. The second gold mineralization event, recorded in the rims of xenotime (135.46 ± 0.93 Ma, weighted mean 206Pb/238U age), is characterized by the mineral assemblage of native gold-calaverite (AuTe2)-petzite (AuAg3Te2)-tellurobismuthite (Bi2Te3). Our study implies that the large-scale Jurassic mineralization event in eastern China, related to flat subduction of the paleo-Pacific plate beneath the eastern China continent, also caused widespread gold mineralization in the Qinling-Dabie Orogen, in addition to production of its world-class porphyry Mo deposits. The fact that only a few Jurassic gold mineralization ages have been reported before, may be due to the lack of suitable geochronometers to record the earlier Jurassic hydrothermal processes, which have been overprinted by the better-recognized Early Cretaceous gold mineralization event. This study also presents a rare example of xenotime compositional alterations and resetting of U-Pb ages induced by low to moderate salinity carbono-aqueous fluids at low temperatures. The textural relationships between gold minerals in contact with such composite xenotime crystals demonstrate that they could have precipitated before, coeval with, or after the dated domains. Since low to moderate salinity carbono-aqueous fluids are commonly involved in the formation of lode gold deposits, it is crucial to examine xenotime textures and recognize potential alteration textures before carrying out isotopic dating of xenotime collected from these deposits. Without prior compositional and textural characterization, attempts to date such composite crystals could yield mixed dates and meaningless ages.

In this work, cabbage-like NiCo₂S₄/MoS₂ assemblies are prepared via a simple hydrothermal process. The as-prepared product as electrode material possesses a specific capacitance of 612 C g⁻¹ at 1 A g⁻¹ and 94% capacitance retention after 10000 cycles at 10 A g⁻¹. Furthermore, the as-assembled asymmetric supercapacitor exhibits an energy density of 73.3 Wh kg⁻¹ at a power density of 453.4 W kg⁻¹. It demonstrates that the cabbage-like structures present promising applications in future energy storage devices.