The Cornubian Batholith (SW England) is an archetypal Variscan rare metal granite with potential for Li-mica mineralization. We present a petrographic, trace element and multivariate statistical study of micas from the Cornubian Batholith granite series and related hydrothermally altered units to assess the role of magmatic vs subsolidus processes and of fluxing elements (F and B) on the Li cycle during the evolution of the system. The mica types are as follows: (1) magmatic, which include Fe-biotite, protolithionite I and phengite-muscovite from the most primitive granites, and zinnwaldite I from more fractionated lithologies; (2) subsolidus, which encompass high-temperature autometasomatic Li-micas and low-temperature hydrothermal muscovite-phengite. Autometasomatic species include protolithionite II, zinnwaldite II and lepidolite, which were observed in the most fractionated and hydrothermally altered units, and occur as replacements of magmatic micas. Low-temperature hydrothermal Li-poor micas formed via alteration of magmatic and autometasomatic micas or as replacement of feldspars, and albeit occur in all studied lithologies they are best represented by the granite facies enriched in metasomatic tourmaline. The evolution of micas follows two major trends underlining a coupling and decoupling between the Li(F) and B fluxes. These include as follows: (1) a Li(F)-progressive trend explaining the formation of protolithionite I and zinnwaldite I, which fractionate Li along with Cs, Nb and Sn during the late-magmatic stages of crystallization, and of zinnwaldite II and lepidolite forming from the re-equilibration of primary micas with high-temperature Li-B-W-Tl-Cs-Mn-W-rich autometasomatic fluids; (2) a Li(F)-retrogressive trend explaining the low-temperature hydrothermal muscovitization, which represents the main Li depletion process. Trace element geochemistry and paragenesis of late muscovite-phengite support that muscovitization is a district-scale process that affected the upper parts of the granite cupolas through acidic and B(Fe-Sn)-saturated hydrothermal fluids associated with metasomatic tourmalinization, which were mixed with a low Eh meteoric component.

Cornubian Batholith（英格兰西南部）是典型的瓦里斯稀有金属花岗岩，具有锂云母矿化潜力。我们对来自 Cornubian 岩基花岗岩系列和相关热液蚀变单元的云母进行岩相学、微量元素和多元统计研究，以评估岩浆与亚固相线过程以及流动元素（F 和 B）在锂循环过程中的作用。系统。云母类型如下：（1）岩浆岩，包括来自最原始花岗岩的铁黑云母、原锂云母I和多硅云母白云母，以及来自更分异岩性的红华云母I； (2)亚固相线，包括高温自交代锂云母和低温热液白云母-多硅白云母。自交代物质包括原锂矿 II、紫云母 II 和锂云母，它们在分馏和热液蚀变程度最高的单元中观察到，并作为岩浆云母的替代物出现。低温热液贫锂云母是通过岩浆和自交代云母的蚀变或作为长石的替代而形成的，尽管出现在所有研究的岩性中，但它们最好的代表是富含交代电气石的花岗岩相。云母的演化遵循两个主要趋势，强调Li(F)和B通量之间的耦合和解耦。这些包括如下：(1) Li(F)-渐进趋势解释了原锂矿 I 和紫锌矿 I 的形成，它们在结晶的晚期岩浆阶段与 Cs、Nb 和 Sn 一起分馏，以及紫锌矿 II 和由原生云母与富含 Li-BW-Tl-Cs-Mn-W 的高温自交代流体的再平衡形成的锂云母； （2）Li(F)-回归趋势解释了低温热液白云母化，它代表了主要的锂消耗过程。微量元素地球化学和晚期白云母-白白云母的共生现象支持白云母化是一个区域规模的过程，通过与交代电气石化相关的酸性和 B(Fe-Sn) 饱和热液影响花岗岩冲天炉的上部，这些热液与交代电气石化作用混合在一起。低 Eh 流星成分。