ABSTRACT Fine-fraction K‒Ar dating and illite crystallinity determination were applied on a peculiar pale olive green shale sample from the upper Ediacaran Indreelva Member (Stáhpogieddi Formation, Vestertana Group, Gaissa Nappe Complex) of the Digermulen Peninsula in Finnmark, Arctic Norway, to constrain the age and metamorphic conditions of tectono-thermal overprint. The <2 and <0.2 µm grain-size fractions are almost purely illite and yielded an illite crystallinity (expressed as the Kübler index) of 0.215 Δ° 2θ and 0.228 ∆° 2θ and K‒Ar ages of 403.9 ± 4.2 and 391.5 ± 4.0 Ma, respectively. The K‒Ar ages are interpreted to present late-stage thermal overprint under low epizonal conditions along a localised shear zone, likely post-dating the peak of metamorphism and cleavage generation on the Digermulen Peninsula. Thus, a later tectono-metamorphic event related to the late stage of the Scandian orogeny is locally recorded in the Gaissa Nappe Complex of the Caledonides of Finnmark. This late Scandian event was probably caused by orogenic extensional collapse and appears to have extended at least into Mid-Devonian time.

中文翻译：

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挪威北极 Gaissa Nappe Complex 中的晚加里东期构造热事件：来自 Digermulen 半岛的精细 K-Ar 年代测定和伊利石结晶度的证据

摘要 对挪威北极芬马克 Digermulen 半岛埃迪卡拉纪 Indreelva 上段（Stáhpogieddi 组、Vestertana 组、Gaissa Nappe 复合体）的特殊淡橄榄绿色页岩样品应用精细分数 K-Ar 定年和伊利石结晶度测定，限制构造热套印的年龄和变质条件。<2 和 <0.2 µm 晶粒级分几乎是纯伊利石，其结晶度（以库伯勒指数表示）为 0.215 Δ° 2θ 和 0.228 Δ° 2θ，K-Ar 年龄为 403.9 ± 4.2 和 391.5 ± 4.0马分别。K-Ar 年龄被解释为在沿局部剪切带的低表带条件下呈现晚期热叠印，可能是在 Digermulen 半岛变质作用和解理产生的峰值之后。因此，在芬马克的 Caledonides 的 Gaissa Nappe Complex 中局部记录了与斯堪的亚造山运动晚期相关的后期构造变质事件。这个晚斯堪的亚事件可能是由造山带伸展塌陷引起的，并且似乎至少延续到中泥盆世时期。