The Upper Units of the allochthonous complexes of the NW Iberian Massif constitute a terrane with continental affinity. They represent the vestiges of a Cambrian magmatic arc developed in the periphery of Gondwana (West African Craton) which was involved in the Devonian Variscan collision, undergoing high‐P, high‐T metamorphism. This includes ultramafic rocks, high‐P mafic rocks (eclogites and granulites) and high‐P migmatitic paragneisses. The latter rocks show an extensive migmatization with the leucosomes oriented parallel to the regional foliation. The migmatitic paragneisses are composed of garnet, kyanite, biotite, quartz, plagioclase, K‐feldspar, rutile and Ti‐hematite. Thermodynamic modelling using the measured bulk composition in the NCKFMASTHO system indicates metamorphic peak conditions of ~15 kbar and ~800 to 835°C, followed by a significant cooling. The prograde evolution is assessed by means of a melt‐reintegration approach, using the composition of the garnet and its inclusions. An appropriate composition of liquid is added to the measured bulk composition to emulate the pre‐melting bulk composition. Modelling of this melt‐reintegrated composition allows to identify a colder high‐P episode below ~500°C. Zircon crystals extracted from the leucosomes show overgrowths crystallized from the partial melt at c. 389 Ma (U–Pb system). The P–T–t path proposed reveals a subduction of the peri‐Gondwanan arc‐derived section down to mantle depths. An isobaric heating stage occurred as a result of residence at great depths and/or inception of a transient oceanic basin at c. 395 Ma. The ensuing near‐isothermal exhumation occurred due to the extension related to the inception of the basin, reaching the thermal peak shortly before c. 389 Ma. Subsequent cooling is related to the underthrusting of colder oceanic and transitional crust below the HP‐HT Upper Units.

中文翻译：

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通过熔体再整合方法和热力学模型重建高压混杂岩副片麻岩的前进 pt 历史（异地复合体，西北伊比利亚地块）

西伊比利亚地块的外来复合体的上层单元构成了一个具有大陆亲和性的地体。它们代表了冈瓦纳（西非克拉通）外围发育的寒武纪岩浆弧的遗迹，该岩浆弧参与泥盆纪瓦利斯坎碰撞，经历了高 P、高 T 变质作用。这包括超基性岩、高磷基性岩（榴辉岩和麻粒岩）和高磷混合质副片麻岩。后者的岩石显示出广泛的混杂，白体与区域叶理平行。混合质副片麻岩由石榴石、蓝晶石、黑云母、石英、斜长石、钾长石、金红石和钛赤铁矿组成。使用 NCKFMASTHO 系统中测量的整体成分进行的热力学建模表明~15 kbar 和~800 至 835°C 的变质峰条件，接着是显着的冷却。使用石榴石及其内含物的成分，通过熔体重新整合方法评估顺向演化。将适当的液体成分添加到测量的整体成分中以模拟熔化前的整体成分。对这种熔体重新整合的组合物进行建模可以识别低于 ~500°C 的更冷的高 P 事件。从 leucosomes 中提取的锆石晶体显示从 c 处部分熔体结晶的过度生长。389 Ma（U-Pb 系统）。提出的 P-T-t 路径揭示了近冈瓦纳弧衍生剖面向下俯冲到地幔深度。等压加热阶段是由于居住在很深的地方和/或在 c. 的瞬态海洋盆地的开始而发生的。395 马。随后发生的近等温折返是由于与盆地开始相关的延伸，在 c. 之前不久达到热峰。389 马。随后的冷却与 HP-HT 上部单元下方较冷的海洋和过渡地壳的下冲有关。