Abstract The Solenzara-Fautea unit is composed of Variscan migmatites and garnet-kyanite granulitic gneisses with pyroxenite boudins outcropping between the villages of Fautea and Solenzara in southeast Corsica. We investigated felsic granulite samples exposed at the seashore south of the village of Tarcu to improve existing pressure-temperature (P-T) estimates of the metamorphic evolution. Relictic garnet (Grt1) is overgrown by a second generation of garnet (Grt2) that also appears as small, euhedral crystals in the matrix. The P-T history of the gneiss was reconstructed on the basis of garnet composition and isochemical phase diagrams. Grt1 formed at 1.3–1.75 GPa, 650–700 °C, whereas Grt2 reflects higher temperature conditions between 750 and 800 °C at 0.9 GPa. The P-T conditions obtained for Grt2 formation are supported by the application of Zr-in-rutile thermometry yielding average temperatures of 708–719 °C at 0.9 GPa. Temperatures calculated with ternary feldspar thermometry on reintegrated feldspar compositions are in the range 745–812 °C. Although a precise P-T path could not be obtained, the microstructural evidences and new P-T estimates support two cycles on which each garnet type was formed by prograde metamorphism. We hypothesize that the felsic granulites were part of a series of metamorphic slices of the Variscan Corsica-Sardinia block which were involved into a sequence of deep crustal movements. According to existing geochronological data, the two metamorphic cycles are Variscan and occurred within the time frame 365–335 Ma.

中文翻译：

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法国科西嘉岛南部瓦里斯坎带长英质麻粒岩石榴石中保存的两个变质循环的证据

摘要 Solenzara-Fautea单元由Variscan混合岩和石榴石-蓝晶石麻粒状片麻岩组成，在科西嘉岛东南部的Fautea和Solenzara村之间出露有辉石岩布丁。我们调查了暴露在 Tarcu 村以南海滨的长英质麻粒岩样本，以改进对变质演化的现有压力-温度 (PT) 估计。遗迹石榴石 (Grt1) 被第二代石榴石 (Grt2) 长满，其在基质中也表现为小的自形晶体。片麻岩的 PT 历史是根据石榴石成分和等化相图重建的。Grt1 在 1.3–1.75 GPa、650–700 °C 下形成，而 Grt2 在 0.9 GPa 下反映了 750 到 800 °C 之间的较高温度条件。Grt2 形成获得的 PT 条件得到了金红石中 Zr 温度测量的支持，在 0.9 GPa 下产生了 708-719 °C 的平均温度。使用三元长石测温法计算出的重新整合的长石成分的温度范围为 745-812 °C。虽然无法获得精确的 PT 路径，但微观结构证据和新的 PT 估计支持两种循环，其中每种石榴石类型都是由顺行变质作用形成的。我们假设长英质麻粒岩是 Variscan Corsica-Sardinia 地块的一系列变质切片的一部分，这些切片涉及一系列深地壳运动。根据现有的年代学资料，这两个变质旋回为 Variscan，发生在 365-335 Ma 的时间范围内。