NJG87-3-03
2007
Palaeocurrent data from the Kalak Nappe Complex, northern Norway: a key element in models of terrane affiliation
87
3
pp. 319-328
978-82-92394-39-7

Palaeocurrent data recorded from a 2,000 km2 area of fluvial, cross-bedded metasandstones in the lower thrust sheets of the Kalak Nappe Complex on the Sværholt and Nordkinn peninsulas, Finnmark, show unimodal patterns with low directional variance. Sediment dispersal was directed towards NW to NNE, and sourced in a highland region of crystalline basement (the ‘Finnmark Ridge’) situated to the S-SE. Sedimentary facies changes from south to north reflect a gradual transition from fluvial apron conditions into a marine basin with mudstone and greywacke deposition. This pattern of NW/NNE-directed palaeocurrent flow and facies changes is repeated in the underlying Laksefjord Nappe Complex. Fluvial to shallow-marine, lithostratigraphic successions in the subjacent Gaissa Nappe Complex, parautochthon and autochthon also show a predominant northward dispersal of sediment from the Fennoscandian Shield, but there is a current reversal in the highest exposed formations of the Gaissa with material shedding E-SE off the above-mentioned basement ridge which formed an important palaeodrainage divide. Taken as a whole, the successions constituting the tectonostratigraphy up to and including the lowest 5-6 thrust sheets of the Kalak Nappe Complex on Sværholt and Nordkinn are considered to derive from basement terranes of the Fennoscandian Shield. Recent models requiring that the Kalak Nappe Complex, and indeed the entire sandstone-dominated, Kalak-Seve-Särv allochthons (continental rise prism) of the Scandinavian Caledonides are exotic and derive from either the Laurentian or the Amazonian palaeoplate need to be carefully reconsidered. This is not to deny that some of the higher-lying thrust sheets of the Kalak Nappe Complex may be semi-exotic, with a mixed Timanian-Baltoscandian provenance. The vast area of Fennoscandian crystalline basement concealed beneath the nappes of NW Finnmark and a 200-250 km-wide segment of the continental shelf clearly holds important information that may be revealed only by major drilling programmes.

David Roberts, Geological Survey of Norway (NGU), NO-7491 Trondheim, Norway. (e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.)

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029-196X
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