Metamorphism in extensive nappe terrains: A study of the Central Scandinavian Caledonides
作者:
Per-Gunnar Andréasson,
Roland Gorbatschev,
期刊:
Geologiska Föreningen i Stockholm Förhandlingar
(Taylor Available online 1980)
卷期:
Volume 102,
issue 4
页码: 335-357
ISSN:0016-786X
年代: 1980
DOI:10.1080/11035898009454492
出版商: Taylor & Francis Group
关键词: Metamorphism;isograds;strain;nappes;thrust faults;geothermal gradients;fades;orogeny;P-Tconditions;pangenesis;autochthon;parautochthon;allochthon;Jämtland Supergroup;Lower Allochthon;Middle Allochthon;Offerdal Nappe;Upper Allochthon;Särv Nappe;S
数据来源: Taylor
摘要:
Metamorphism in the nappe terrains of the Central Scandinavian Caledonides is characterized by inverted gradients and other indications of disequilibrium caused by the superposition of nappes of various metamorphic grade and the translation of the nappe pile onto the margin of the Baltic Shield. In the lower nappes there is a gradual westward increase of grade, but some inverted gradients persist. In the upper allochthon, the variation of metamorphism is essentially vertical. It is possible to identify and evaluate parageneses formed prior to, during, and after nappe emplacement. Their interpretation in terms of separate Caledonian or Precambrian events is often ambiguous. Early Caledonian metamorphism apparently represented a range ofP-T-conditions. The build-up and translation of the nappe pile was characterized by transient high pressure conditions. A metamorphic pulse, manifest particularly in the west, succeeded nappe emplacement onto the Baltic Shield. Strain-induced metamorphism in the vicinity of thrusts contributes to the overall metamorphic pattern. A variety ofP/T-ratios characterized metamorphism in the Scandinavian Caledonides. This conclusion modifies current concepts about an essentially Barrovian metamorphic evolution of the orogen.
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