The Cadomian Orogeny formed as an accretionary orogen surrounding Gondwana. The structure resulting from the Cadomian Orogeny is pervasively reworked during the Paleozoic, within the frame of the Variscan Cycle. In SW Iberia (Mina Afortunada Massif), a tectonometamorphic and geochronological analysis revealed two Cadomian deformation phases. The first phase (DC1; 586 Ma, U-Pb dating in inherited metamorphic garnet from Mina Afortunada Gneiss) is associated with ophiolite accretion during the closure of a back-arc or intra-arc basin (Cuartel Ophiolite). A metamorphic fabric related to this phase is preserved as an internal foliation in Ediacaran (meta)sedimentary rocks. The second phase (DC2; 515–485 Ma) is constrained by the age of the igneous protolith of Mina Afortunada Gneiss (∼515 Ma), which is affected by a penetrative foliation formed during DC2, and by the unconformable deposit of Ordovician sediments, which are not affected. The telescoping of metamorphic isograds during DC2 and the geometry of detachment faults associated with this phase suggest extensional tectonics as the driving mechanism for the early exhumation of the Cadomian suture zone in Mina Afortunada Massif. The superimposition of Variscan folds and shear zones onto the Cadomian structures contributed to the subsequent exhumation of the Cadomian suture zone. The analysis and reconstruction of Cadomian and Variscan structures, plus the geochronological data, allow us to correlate the Cuartel Ophiolite with the Mérida Ophiolite, being two pieces of the same, yet dismembered, Cadomian suture zone. The number of Cadomian suture zones in Gondwana does not coincide with that of Cadomian suture zone exposures. Reworked orogens such as the Cadomian could be subjected to duplication of their suture zones. Assessments regarding the Cadomian paleogeography should consider the multiplier effect of the structural overprints after ophiolite accretion.

中文翻译：

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蛇绿岩：冈瓦南周围地区（西南伊比利亚）Cadomian 缝合带的结构、时间和挖掘机制


卡多米亚造山运动是围绕冈瓦纳的增生造山运动形成的。卡多米亚造山运动产生的结构在古生代，在瓦里斯坎旋回的框架内被普遍地改造。在伊比利亚西南地区 （Mina Afortunada Massif），构造变质和地质年代学分析揭示了两个 Cadomian 变形阶段。第一阶段（DC1;586 马，Mina Afortunada 片麻岩继承的变质石榴石中的 U-Pb 测年）与弧后或弧内盆地（Cuartel 蛇绿岩）闭合期间的蛇绿岩增生有关。与此相相关的变质结构在埃迪卡拉纪（变质）沉积岩中作为内部叶状结构保存下来。第二阶段（DC2;515-485 马）受Mina Afortunada片麻岩火成岩原岩年龄（∼515 马）的限制，该原生岩层受到DC2期间形成的穿透性叶子的影响，以及不受影响的奥陶纪沉积物的不整合沉积。DC2 期间变质等生体的伸缩以及与该阶段相关的分离断层的几何形状表明，伸展构造是 Mina Afortunada 地块 Cadomian 缝合带早期挖掘的驱动机制。Variscan 褶皱和剪切带叠加在 Cadomian 结构上有助于随后挖掘 Cadomian 缝合带。对 Cadomian 和 Variscan 结构的分析和重建，加上地质年代学数据，使我们能够将 Cuartel Ophiolite 与 Mérida 蛇绿岩联系起来，它们是同一块，但被肢解的 Cadomian 缝合带。冈瓦纳的 Cadomian 缝合区数量与 Cadomian 缝合区暴露的数量不一致。经过改造的造山带，如 Cadomian 可能会受到其缝合区的复制。 关于卡多米亚古地理学的评估应考虑蛇绿岩增生后结构叠印的乘数效应。