During continental collision, large tracts of crust are mobilised along major shear zones. The metamorphic conditions at which these zones operate, the duration of thrusting, and the deformation processes that facilitated hundreds of km of tectonic transport are still unclear. In the Scandinavian Caledonides, the Lower Seve Nappe displays a main mylonitic foliation with thickness of ~1 km. This foliation is overprinted by a brittle‐to‐ductile deformation pattern localized in C and C’‐type shear bands proximal to the tectonic contact with the underlying Sarv Nappe. Thermobarometry of amphibolites and micaschists suggest a first high‐pressure stage at 400‐500°C and 1‐1.3 GPa recorded in mineral relics. The main mylonitic foliation developed under epidote amphibolite facies conditions along the retrograde path from 600°C and 1 GPa to 500°C and 0.5 GPa. Age dating of synkinematic titanite grains in the amphibolites indicates that this mylonitic fabric formed at around 417 ± 9 Ma, but older ages spanning 460‐430 Ma could represent earlier stages of mylonitization. The shear bands developed at lower metamorphic conditions of 300‐400°C and ~0.3 GPa. In the micaschists, the recrystallized grain size of quartz decreases towards the shear bands. Monomineralic quartz layers are eventually dismembered to form polyphase aggregates deforming by dominant grain size sensitive creep accompanied by slip in muscovite and chlorite. Plagioclase zoning truncations suggest that the shear bands originated by fracturing followed by ductile deformation. The results suggest protracted and long‐lasting shearing under amphibolite to greenschist facies conditions during the juxtaposition, stacking and exhumation of the Lower Seve Nappe.

中文翻译：

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斯堪的纳维亚 Caledonides 大规模逆冲过程中地壳中部条件下的长期剪切

在大陆碰撞期间，大片地壳沿主要剪切带移动。这些带运行的变质条件、逆冲的持续时间以及促成数百公里构造运输的变形过程仍不清楚。在斯堪的纳维亚 Caledonides 中，Lower Seve Nappe 显示出厚度约为 1 公里的主要糜棱岩叶理。这种叶理由脆性到韧性变形模式覆盖，位于 C 和 C' 型剪切带中，靠近与下伏 Sarv Nape 的构造接触。角闪石和云母片的热气压测量表明在矿物遗迹中记录的 400-500°C 和 1-1.3 GPa 的第一高压阶段。主要糜棱岩叶理在绿帘石角闪岩相条件下沿逆行路径从 600°C 和 1 GPa 发展到 500°C 和 0。5GPa。角闪岩中同运动的钛石颗粒的年代测定表明，这种糜棱岩结构形成于大约 417 ± 9 Ma，但跨越 460-430 Ma 的较旧年龄可能代表糜棱岩化的早期阶段。剪切带在 300-400°C 和~0.3 GPa 的较低变质条件下形成。在云母片中，石英的再结晶晶粒尺寸朝着剪切带减小。单矿物石英层最终被肢解形成多相聚集体，通过主要的晶粒尺寸敏感蠕变伴随着白云母和绿泥石的滑移而变形。斜长石分区截断表明剪切带起源于压裂，然后是韧性变形。结果表明，在并置过程中，角闪岩与绿片岩相条件下发生长期和持久的剪切作用，