NJG68-4-01
1988
Metamorphic history in the Bergen Arcs, Norway, as determined from amphibole chemistry
68
4
223-239

Electron microprobe analyses of amphiboles and other metamorphic minerals give new information about
the metamorphic development in the Major and Minor Bergen Arcs in the Scandinavian Caledonides. The
composition of metamorphic amphiboles in Ashgillian-Llandoverian metasediments indicates that the
Caledonian metamorphism in the two arcs reached its peak of upper greenschist close to lower amphibolite
facies during the main Caledonian (Scandian) event (M2). This result is supported by high Al2O3/FeO + Fe2O3 ratios in white micas and by almandine-rich garnets. Medium pressures are indicated forĀ this event. Old, unstable amphibole porphyroclasts are actinolites to actinolitic hornblendes, and indicateĀ a pre-Ashgillian event (M1) of lower metamorphic grade.

0029-196X
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