The impact of fluorine on phase relations and clinopyroxene–melt element partitioning has been explored experimentally to better understand the effect of this halogen on the residual enrichment of the REE and HFSE during crystallisation of alkaline and peralkaline magmas. Clinopyroxene was grown from three $$\hbox {H}_2\hbox {O}$$ H 2 O -saturated synthetic glasses of tephriphonolite-to-phonolite composition in a rapid quench internally heated pressure vessel at 650–800 $$^\circ$$ ∘ C and 200 MPa, with $$\Delta$$ Δ log $$f\hbox {O}_{{2}}$$ f O 2 fixed to ca. FMQ + 1. The fluorine content in the charges was varied and produced quenched melts from fluorine-free to 1.6 wt.% F. The experiments yield an assemblage of melt, fluid, sodic clinopyroxene, biotite, magnetite, ± K-feldspar, ± titanite, ± fluorite, and ± hiortdahlite (a Na-Ca-Ti-F sorosilicate). Addition of fluorine markedly increases the mode of biotite without significantly affecting the mode of clinopyroxene. Relative to fluorine-free compositions, experiments with 1.6 wt.% fluorine in the melt show a strong decrease in clinopyroxene–melt partition coefficients for the trivalent REE La–Dy and Y with a lesser decrease for the $$D_{\mathrm{HREE}}$$ D HREE and $${D_{\mathrm{HFSE}}}^{4+}$$ D HFSE 4 + . The diminished uptake of these metals by clinopyroxene may reflect changes to their speciation in the melt phase, consistent with the formation of REE-F complexes and with modifications to the medium-range structural environment around $$\hbox {HFSE}^{4+}$$ HFSE 4 + ions in the melt. An increase in the fluorine content of the melt will thus make the REE and $$\hbox {HFSE}^{4+}$$ HFSE 4 + progressively less compatible and, therefore, available for residual enrichment.

中文翻译：

---

氟对单斜辉石/熔体微量元素分配的影响

氟对相关系和单斜辉石-熔体元素分配的影响已经通过实验进行了探索，以更好地了解这种卤素对碱性和过碱性岩浆结晶过程中 REE 和 HFSE 残余富集的影响。单斜辉石是从三个 $$\hbox {H}_2\hbox {O}$$ H 2 O 饱和合成玻璃中的 tephriphonite-to-phonolite 组成的合成玻璃在 650–800 $$^\ 的快速淬火内部加热压力容器中生长的circ$$ ∘ C 和 200 MPa，$$\Delta$$ Δ log $$f\hbox {O}_{{2}}$$ f O 2 固定为大约。FMQ + 1. 改变装料中的氟含量并产生从无氟到 1.6 wt.% F 的淬火熔体。实验产生熔体、流体、钠斜辉石、黑云母、磁铁矿、± K-长石、±钛石，±萤石，和 ± hiortdahlite（Na-Ca-Ti-F 硅酸盐）。添加氟显着增加了黑云母的模态，而不会显着影响单斜辉石的模态。相对于无氟组合物，熔体中含 1.6 wt.% 氟的实验表明，三价 REE La-Dy 和 Y 的单斜辉石-熔体分配系数显着降低，而 $$D_{\mathrm{HREE }}$$ D HREE 和 $${D_{\mathrm{HFSE}}}^{4+}$$ D HFSE 4 +。单斜辉石对这些金属的吸收减少可能反映了它们在熔融阶段的形态变化，这与 REE-F 配合物的形成以及 $$\hbox {HFSE}^{4+ 周围的中程结构环境的改变一致}$$ HFSE 4 + 熔体中的离子。