Abstract

Mr S. Hayes Writes: I read with interest the paper by B. A. Sturt et al. as one who is currently researching in the region.

I have been studying the metamorphic fabrics in the Kalak metasediments (amphibolite facies) on the mainland opposite Magerøy where the Silurian succession is thrust over the Kalak complex. The time sequence for deformation proposed by the authors, based upon dating of the syn-orogenic igneous bodies of the Seiland Igneous Province in W Finnmark, can be correlated, at least in part, with textural features exhibited by the Kalak units. This has particular relevance since no igneous intrusives occur in the area, which is over 50 km NE of Seiland.

The polyphase deformation sequence can here be attributed to D1 and D2 events. Porphyroblastic mineral growth occurred during the interkinematic D1–D2 peak of metamorphism and is well documented in garnet crystal growth. These overgrew the S1 foliation, preserving a relict internal fabric, Si1. Growth continued during D2, preserving the S2 foliation, termed Si2. All such garnets are ‘augened’ by the regional Caledonoid schistosity which is S2 and defines the matrix foliation (Se). A later period of garnet growth then overgrew the S2 foliation and demonstrates the complexity of the Se.

The garnets show optical zoning and show clearly a relationship between garnet growth and foliation development. Several dominant features emerge:

1. Garnets have a size range of 0.5–2.5 mm.

2. Cores to garnets are idioblastic with minor inclusions of quartz and micas. Preservation of Si1 fabric is

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