The regional significance of the Caledonian structures of the Sandland Peninsula, West Finnmark, northern Norway

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Abstract
A detailed analysis of the mesoscopic structures of the Sandland peninsula is used as the key to the synthesis of the structural history of the Loppen district. Three fold episodes are recognized. F 1 has folded the meta-sediments around the westerly-facing Haettekjeilen syncline, the steep, partly inverted easterly limb of which forms the Sandland peninsula and Silda, whilst the flat-lying westerly limb forms Loppa, the Andsnes peninsula, the Olderfjord meta-sediments and outcrops in the Kvaenangan Fjord. On Skjervøy, south of the Kvaenangan Fjord, the succession lies on the inverted limb of a westerly facing anticline, the axial trace of which must pass between Skjervøy and the Kvaenangan Gabbro. These large westerly facing F 1folds contrast with the large easterly facing F 1 folds reported from Sørøy by Ramsay & Sturt (1963). Between the two areas a major F 1anticlinal rise with a n–s trend is envisaged passing to the south of Sørøy and through the Loppen district where it follows the outcrop of the oldest meta-sediments exposed. These are intruded by a series of layered basic and ultrabasic bodies. Three sets of F 2 folds are described: major warps with vertical planes and a conjugate pair developed around easterly and westerly dipping axial planes. All have the same axial trend but develop on different parts of the F 1fold system. The suggested maximum stress responsible was nearly horizontal in an e–w direction, very similar to that responsible for F 1 and therefore unlikely to have modified greatly the regional orientation of the F 1structures. Later ( F 3) strain-slip cleavage and mild warps are associated with minor faults, shear zones and joints on near vertical planes with trends of 340°, 280° and 70°.

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