The occurrence of Lower Paleozoic mafic magmatic rocks in the Central Iberian Zone (CIZ) of the Variscan Orogen is rare. Amphibolites and metagabbros embedded in the metasediments of the Douro-Beiras Supergroup outcrop at Farminhão, Viseu (central-north Portugal). The protoliths of these two rock types are tholeiites presenting different isotopic signatures (εNd₄₈₀ = +4.63 to +4.93 and +5.74 to +7.67) and incompatible element ratios (normalized La/Lu up to 4.5 and down to 0.7), respectively which suggests they are not cogenetic. The closely related meta-ultramafic rocks are considered as cumulates generated from the magmas that originated the metagabbros. The elemental and isotopic features of the metagabbros are similar to those reported for amphibolitic occurrences in Tenzuela (near Segovia, Spain) which allows the proposition of a similar age for the mafic rocks of Farminhão. Despite the depleted characteristics of the studied rocks, they are interpreted as having been formed during a continental rifting process characterized by variable degrees of stretching, some 100 Ma after the end of the deposition of the Douro-Beiras Supergroup. This rifting event marks the onset of the Variscan Cycle (s.l.) in the Central Iberian Zone. The occurrence of these metabasic rocks near the confluence between the Porto-Viseu Metamorphic Belt and the Juzbado-Penalva do Castelo Shear Zone suggests that these first-order structures may have worked as weakness zones constraining the ascent of magmas during the Ordovician. The Lower Ordovician metabasic rocks here studied are chemically similar to the abundant lower to medium Cambrian magmatic rocks of the Ossa Morena Zone, also in Iberia, further reinforcing the diachronous character of the opening of the Rheic Ocean that later propagated to the eastern sectors of the European Variscan Belt.

瓦里斯坎造山带伊比利亚中部带（CIZ）的下古生界基性岩浆岩很少见。角闪岩和长辉长岩嵌入维塞乌（葡萄牙中北部）的 Farminhão 的 Douro-Beiras 超群露头的变质沉积物中。这两种岩石类型的原岩是拉斑岩，具有不同的同位素特征 (εNd ₄₈₀ = +4.63 至 +4.93 和 +5.74 至 +7.67）和不相容元素比率（标准化的 La/Lu 高达 4.5 和低至 0.7），这表明它们不是共同遗传的。密切相关的变质超镁铁质岩石被认为是由起源变长岩的岩浆产生的堆积物。后辉长岩的元素和同位素特征与 Tenzuela（西班牙塞哥维亚附近）的角闪岩事件报告的特征相似，这使得 Farminhão 的基性岩具有相似年龄的命题。尽管所研究的岩石具有枯竭的特征，但它们被解释为是在大陆裂谷过程中形成的，该过程以不同程度的拉伸为特征，在杜罗-贝拉斯超群沉积结束后约 100 Ma。这个裂谷事件标志着瓦利斯坎循环（sl ) 在伊比利亚中部地区。这些变质岩出现在波尔图-维塞乌变质带和 Juzbado-Penalva do Castelo 剪切带交汇处附近，表明这些一级构造可能在奥陶纪期间作为限制岩浆上升的弱带起作用。此处研究的下奥陶统变质岩在化学上与同样位于伊比利亚的奥萨莫雷纳带中丰富的中寒武纪岩浆岩相似，进一步加强了后来传播到西洋东部地区的莱茵洋开口的历时特征。欧洲 Variscan 腰带。这些变质岩出现在波尔图-维塞乌变质带和 Juzbado-Penalva do Castelo 剪切带交汇处附近，表明这些一级构造可能在奥陶纪期间作为限制岩浆上升的弱带起作用。此处研究的下奥陶统变质岩在化学上与同样位于伊比利亚的奥萨莫雷纳带中丰富的中寒武纪岩浆岩相似，进一步加强了后来传播到西洋东部地区的莱茵洋开口的历时特征。欧洲 Variscan 腰带。这些变质岩出现在波尔图-维塞乌变质带和 Juzbado-Penalva do Castelo 剪切带交汇处附近，表明这些一级构造可能在奥陶纪期间作为限制岩浆上升的弱带起作用。此处研究的下奥陶统变质岩在化学上与同样位于伊比利亚的奥萨莫雷纳带中丰富的中寒武纪岩浆岩相似，进一步加强了后来传播到西洋东部地区的莱茵洋开口的历时特征。欧洲 Variscan 腰带。