The Caledonide Geology of Scandinavia

ISBN-13: 9781853330674 / Angielski / Twarda / 1989 / 312 str.

R. a. Gayer;University College

Opis

work on structural and stratigraphic relationships is presented from various parts of the mountain belt. In the first paper of the section, R. O. Greiling (Heidelberg) describes the Middle Allochthon of Vasterbotten, northern Sweden, where tectonic windows through the Upper Allochthon (Seve Nappe) show that the Middle Allochthon has a similar lithostratigraphy to that of the Stalon Nappe Complex of the eastern Caledonian margin but with a more ductile deformation and metamorphosed to a higher grade following thrust emplacement. These relations are explained by suggesting that the window rocks were initially subducted beneath a colliding western plate but were later accreted to the base of the western plate and thrust with it. The thrust geometry of the windows, described as antiformal stacks, agrees with this model. The Middle Allochthon of the Caledonian margin in northern Sweden is described by R. O. Greiling and R. Kumpulainen (Heidelberg and Stockholm) who record two distinct metasedimentary units separated by a thick zone of mylonites interpreted as a lateral thrust ramp. Turbidites in the northern unit were derived from an unidentified igneous source to the east and cannot be correlated with other sequences in the Middle Allochthon. In another paper dealing with the northern Swedish Caledonides, L. Hansen (Uppsala) describes down-to-the-west normal faults cutting the autochthonous Cambrian sediments in the tunnel sections of the Vietas Hydropower Station, but themselves being truncated by the basal decollement of the Lower Allochthon.

Spis treści

I — Finnmarkian Geology.- 1. U-Pb ages of nepheline syenite pegmatites from the Seiland Magmatic Province, N Norway.- 2. Chronology of Caledonian tectonothermal activity within the Gaissa and Laksefjord Nappe Complexes (Lower Allochthon), Finnmark, Norway: evidence from K-Ar and 40Ar/39 Ar ages.- 3. Regional correlations in NE Troms-W Finnmark: the demise of the “Finnmarkian” orogeny?.- 4. Evidence of intracratonic Finnmarkian orogeny in central Norway.- 5. The timing of orogenesis in northern Norway: did the Finnmarkian orogeny occur?.- II — Regional Geology.- 6. The Middle Allochthon in Västerbotten, northern Sweden: tectonostratigraphy and tectonic evolution.- 7. The Middle Allochthon of the Scandinavian Caledonides at Kvikkjokk, northern Sweden: sedimentology and tectonics.- 8. Age Relationships between Normal and Thrust Faults near the Caledonian Front at the Vietas Hydropower Station, Northern Sweden.- 9. Basement-cover evolution during Caledonian orogenesis, Troms, N Norway.- 10. The structure and stratigraphy of the southwestern portion of the Gaissa Thrust Belt and the adjacent Kalak Nappe Complex, Finnmark, N Norway.- 11. Palaeogeographic reconstruction of the pre- to syn-Iapetus rifting sediments in the Caledonides of Finnmark, N Norway.- III — Igneous Geology.- 12. Basic igneous rocks from a portion of the Jotun Nappe: evidence for Late Precambrian ensialic extension of Baltoscandia?.- 13. The geochemistry of the Sulitjelma ophiolite and associated basic volcanics: tectonic implications.- 14. Xenolithic dykes on Seiland and preliminary observations on the lithospheric mantle beneath the Seiland Province, W Finnmark, Norway.- IV — Metamorphic Geology.- 15. Evolution of low-grade metamorphic zones in the Galedonides of Finnmark, N Norway.- 16. Metamorphic evolution of the Caledonian nappes of north central Scandinavia.- 17. High-pressure ultramafic rocks from the allochthonous nappes of the Swedish Galedonides.- 18. Status of the supracrustal rocks in the Western Gneiss Region, S Norway.- V — Palaeontology and Biostratigraphy.- 19. The stratigraphy and faunas of the Par autochthon and Lower Allochthon of southern Norway.- VI — Devonian Geology.- 20. Microtectonic evidence of Devonian extensional westward shearing in southwest Norway.- VII — East Greenland Caledonian Geology.- 21. The Late Proterozoic sedimentary record of East Greenland: its place in understanding the evolution of the Galedonide Orogen.- 22. Carbonate shelf and slope facies evolution prior to Vendian glaciation, central East Greenland.- 23. Dolomitic stromatolite-bearing units with storm deposits from the Vendian of East Greenland and Scotland: a case of facies equivalence.- 24. The Tillite Group and related rocks of East Greenland: implications for Late Proterozoic palaeogeography.- 25. The structural setting of the Late Proterozoic tillites of East Greenland.