Abstract

The paper presents experimental data on the interaction of amphibole with NaCl–H₂O and (K, Na)Cl–H₂O solutions at varying salt content. When interacting with H₂O–NaCl fluid, amphibole remains the predominant mineral in all experiments, and the newly formed minerals are Na-phlogopite, plagioclase, and nepheline/sodalite. At \({{a}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}}\) > 0.6, the amphibole melts. When amphibole interacts with H₂O–NaCl–KCl fluid at \({{X}_{{{{{\text{H}}}_{2}}{\text{O}}}}}\) < 0.40 and Х_KCl/(Х_KCl + Х_NaCl) in the fluid, defined as Х_NaCl = 0.506 – 0.84Х_KCl, the amphibole is replaced by the association of nepheline with sodic plagioclase, sodalite, and biotite. At Х_KCl/(Х_KCl + Х_NaCl) > 0.3, nepheline, sodalite, and plagioclase become unstable, K-feldspar is formed, and biotite, clinopyroxene, and amphibole remain stable. At Х_KCl/(Х_KCl + Х_NaCl) > 0.5, the association Cpx + Bt + Kfs + Grt (grossular–andradite) is stable. Thus, grossular–andradite garnet is an indicator of a high potassium activity in the fluid, whereas nepheline testifies that the sodium activity was high. Na → K exchange is typical of the amphibole and biotite, and Ca → Na exchange occurs in the clinopyroxene, and all of these minerals (but neither nepheline nor garnet) remain generally stable within a wide range of the K/Na ratio in the fluid. Clinopyroxene in the experiments spans Ca–Fe–Mg compositions with a varying, sometimes high, Al content, and the amphiboles belong to the pargasite–hastingsite series. With an increase in \({{a}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}}\) (\({{X}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}}\) > 0.57), i.e., a decrease in the gross salinity of the fluid, melts are generated, and their composition varies from trachyte to phonolite. An increase in the Х_KCl/(Х_KCl + Х_NaCl) ratio in the fluids leads to a decrease in alumina content of the melts. An increase in the total salinity of the fluid leads to an increase in the content of potassium in the melt and a decrease in the content of chlorine in it. The experiments have shown that interaction between amphibole and fluids containing high NaCl and KCl concentrations results in mineral associations typically produced by alkaline metasomatism of amphibole-bearing rocks and concomitant HCl enrichment in the fluid phase. The substitution of highly saline fluids for highly acidic ones leads to the leaching of Ca, Mg, Fe from the metamorphic rocks, and the transport and redeposition of these components. It follows that significant removal of FeO, MgO, CaO from rocks is sometimes a consequence of the interaction of the host rocks with saline aqueous solutions.

中文翻译：

---

750°C、700 MPa 下角闪石与高盐度 H2O-NaCl-KCl 流体相互作用的实验研究：对角闪石岩石碱性交代作用的影响

摘要

本文提供了不同盐含量下角闪石与 NaCl-H ₂ O 和 (K, Na)Cl-H _{2 O 溶液相互作用的实验数据。}当与H ₂ O-NaCl流体相互作用时，角闪石仍然是所有实验中的主要矿物，新形成的矿物是钠金云母、斜长石和霞石/方钠石。当\({{a}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}}\) > 0.6 时，角闪石熔化。当角闪石与 H ₂ O–NaCl–KCl 流体在\({{X}_{{{{{\text{H}}}_{2}}{\text{O}}}}}\) < 0.40 且流体中 Х KCl /( Х KCl + Х _NaCl )相互作用_时，定义_为Х_NaCl = 0.506 – 0.84 Х _KCl，角闪石被霞石与钠斜长石、方钠石和黑云母的缔合所取代。当Х _KCl /( Х _KCl + Х _NaCl ) > 0.3时，霞石、方钠石和斜长石变得不稳定，形成钾长石，而黑云母、单斜辉石和角闪石保持稳定。当Х _KCl /( Х _KCl + Х _NaCl ) > 0.5 时，关联Cpx + Bt + Kfs + Grt（钙铝榴石-钙铁榴石）是稳定的。因此，钙铝榴石-钙铁榴石石榴石是液体中钾活性高的指标，而霞石则证明钠活性高。Na → K 交换是角闪石和黑云母中的典型现象，Ca → Na 交换发生在单斜辉石中，并且所有这些矿物（霞石和石榴石除外）在流体中的 K/Na 比值较宽的范围内总体上保持稳定。实验中的单斜辉石涵盖了具有变化的、有时高的铝含量的Ca-Fe-Mg组合物，并且角闪石属于斜闪石-黑斯廷石系列。随着 \({{a}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}}\) 的增加 ( \({{X}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}} } \ )> 0.57)，即流体总盐度降低，产生熔体，其成分从粗面岩到响岩不等。Х _KCl /( Х _KCl + Х _NaCl的增加) 流体中的比例导致熔体中氧化铝含量的降低。流体总盐度的增加导致熔体中钾含量的增加和其中氯含量的减少。实验表明，角闪石与含有高浓度 NaCl 和 KCl 的流体之间的相互作用会导致矿物组合，这些矿物组合通常由含角闪石岩石的碱性交代作用以及伴随的流体相中的 HCl 富集产生。高盐流体替代高酸性流体导致钙、镁、铁从变质岩中浸出，以及这些成分的迁移和再沉积。由此可见，岩石中 FeO、MgO、CaO 的显着去除有时是主岩与盐水溶液相互作用的结果。