The age and distribution of basement rocks in the Caledonide orogen of the N Atlantic
Por:
Powell D., Andersen T.B., Drake Jr A.A., Hall L., Keppie J.D.
Publicada:
1 ene 1988
Resumen:
Available isotopic data suggest that the Precambrian basement elements of the northern parts of the Caledonide orogen in N America, Britain, Ireland, Greenland and Scandinavia comprise largely Grenvillian and Svecofennian continental crust. Archaean precursors have been identified in Greenland. Norway and Britain, but not positively in the Appalachians. Early Caledonian (Grampian-Finnmarkian) orogenic activity gave rise, in the Scandinavian and British-Irish sectors, to an early Palaeozoic basement which, in Norway, is overlain by Ordovician to Silurian supracrustal sequences. In contrast, a late Precambrian-early Cambrian (Cadomian-Avalonian and older) basement is present in southern parts of the orogen. The distribution of these basement elements constrains any plate-tectonic reconstructions of the N Atlantic Caledonide orogen and suggests that the orogen was tripartite during its early development. Further, it suggests that transcurrent movements as well as obduction may have been important tectonic processes during Grampian-Finnmarkian tectonism. -Authors
Filiaciones:
Dept. of Geol., Royal Holloway & Bedford New College, Univ. of London, Egham, Surrey, TW20 0EX, UK
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