Abstract—

The paper summarizes authors' earlier and newly obtained experimental data on the formation of phlogopite and chromium-bearing potassium titanates of the crichtonite, magnetoplumbite, and hollandite groups, which are indicator minerals that characterize various stages of modal metasomatism in the upper mantle. Phlogopite-forming reactions were studied in the garnet–orthopyroxene system in the presence of H₂O–KCl fluid at 3 and 5 GPa and 900–1000°C as simulating phlogopite formation in garnet peridotites and pyroxenites. Experiments have demonstrated regular variations in Ca and Cr contents in the garnet and Al in the pyroxenes, as well as the composition of the newly formed phlogopite, depending on the concentration of the potassium component (KCl or K₂CO₃) of the fluid. Experiments on the formation of potassium titanates (yimengite, mathiasite, and priderite) in the chromite–rutile/ilmenite–K₂CO₃–H₂O–CO₂ system at 3.5 and 5 GPa and 1200°C have proved that these minerals can be formed when chromite reacts with potassic aqueous–carbonic fluid, but these reactions require additional sources of titanium. These sources may be rutile and/or ilmenite, which are usually also produced by modal metasomatism of peridotites. The experiments thus confirm that the formation of titanates marks the most advanced stages of metasomatism in mantle peridotites. The experiments have shown that the formation of potassium titanates follows the formation of phlogopite, whereas assemblages of the titanates with phlogopite are produced at higher concentrations of the potassium component of the fluid than phlogopite alone. The relationships between the titanates are also a function of the activity of the potassium component in the fluid and, probably, pressure. The relationships and trends reproduced in the experiments clearly illustrate features of mineral assemblages and variations in compositions of minerals from metasomatized peridotites in the lithospheric mantle.

中文翻译：

---

形成金云母和钛酸钾的反应作为上地幔交代作用的矿物指标的实验研究

摘要-

该论文总结了作者较早和新获得的关于锂辉石、磁铅石和荷兰石群的金云母和含铬钛酸钾形成的实验数据，这些矿物是表征上地幔不同阶段模态交代的指示矿物。在 3 和 5 GPa 和 900-1000°C的 H ₂ O-KCl 流体存在下，研究了石榴石-斜辉石系统中的金云母形成反应，以模拟石榴石橄榄岩和辉石岩中的金云母形成。实验表明，石榴石中的 Ca 和 Cr 含量以及辉石中的 Al 含量以及新形成的金云母的成分都有规律的变化，这取决于钾成分（KCl 或 K ₂ CO ₃) 的流体。在铬铁矿-金红石/钛铁矿-K ₂ CO ₃ -H ₂ O-CO _{2 中}形成钛酸钾（伊蒙铁矿、马铁矿和紫铁矿）的实验在 3.5 和 5 GPa 和 1200°C 下的系统已经证明，当铬铁矿与碳酸钾水溶液反应时，可以形成这些矿物质，但这些反应需要额外的钛源。这些来源可能是金红石和/或钛铁矿，它们通常也由橄榄岩的模态交代产生。因此，实验证实钛酸盐的形成标志着地幔橄榄岩交代作用的最高级阶段。实验表明，钛酸钾的形成跟随金云母的形成，而钛酸盐与金云母的组合是在流体中钾组分的浓度高于单独的金云母时产生的。钛酸盐之间的关系也是流体中钾成分的活性和可能是压力的函数。