Wang Yicun, Wang Keyong, Konare Yassa
College of Earth Sciences, Jilin University, Changchun, 130061, China.
Sci Rep. 2018 Apr 4;8(1):5662. doi: 10.1038/s41598-018-22227-7.
Nearly pure N fluid inclusions (T (L) = -151-168 °C; T (V) = ~150.3 °C) were identified in W-mineralized quartz veins from the Yangjingou scheelite deposit, in the eastern Yanbian area, NE China. Other fluid inclusion populations include N-CO, NaCl-HO ± N and CO ± N-NaCl-HO, but no hydrocarbons were detected. The host rocks are part of the Wudaogou Group metamorphic series, which mainly consist of Ca-rich mica schist. Subhedral sulfide minerals occur in early disseminated W-mineralized quartz veins, or have partially replaced early scheelite. T and T indicate N fluid-trapping from 315 °C to 410 °C and from 80 MPa to 350 MPa. Oxygen and hydrogen isotopic data (δD = -74.9‰-77‰, δO = 9.6‰~12‰, V-SMOW) suggest that the mineralizing fluids were composed of mixed magmatic and metamorphic water, N-rich inclusions (δN = -0.5‰ to 1.4‰) indicate fluid-rock interaction with metamorphic rocks. The N-rich fluid was closely associated with scheelite precipitation. During thermal decomposition under high oxygen fugacity conditions, which occurred synchronously with metamorphism and magmatic activity, large amounts of N were liberated from NH-micas, which then accumulated in the parent fluid of the quartz scheelite veins.
在中国东北延边地区东部的杨金沟白钨矿矿床的钨矿化石英脉中，识别出了近乎纯的N流体包裹体（液相温度T（L）= -151-168℃；汽相温度T（V）= ~150.3℃）。其他流体包裹体组合包括N-CO、NaCl-H₂O±N和CO₂±N-NaCl-H₂O，但未检测到烃类。容矿岩石是五道沟群变质岩系的一部分，主要由富钙云母片岩组成。半自形硫化物矿物出现在早期浸染状钨矿化石英脉中，或部分交代了早期白钨矿。T（L）和T（V）表明N流体在315℃至410℃、80MPa至350MPa条件下被捕获。氧和氢同位素数据（δD = -74.9‰-77‰，δ¹⁸O = 9.6‰~12‰，V-SMOW）表明成矿流体由岩浆水和变质水混合组成，富N包裹体（δ¹⁵N = -0.5‰至1.4‰）表明流体与变质岩发生了相互作用。富N流体与白钨矿沉淀密切相关。在与变质作用和岩浆活动同步发生的高氧逸度条件下的热分解过程中，大量的N从铵云母中释放出来，然后在石英白钨矿脉的母液中积累。
