The Caledonian Sequence in Ny Friesland, Spitsbergen

Abstract

Arising mainly out of observations in the last decade the structure of the Ny Friesland sector of Spitsbergen is outlined for the first time and summarized in a map and sections. It is interpreted as reflecting the formation of a geosyncline of Hecla Hoek rocks (late Pre-Cambrian to mid-Ordovician), and their deformation in the Ny Friesland orogeny, with the formation of gneisses and with the emplacement of “post-tectonic” batholiths, followed by Old Red Sandstone deposition and deformation in the Svalbard folding. Thus a mobile history (the Caledonian sequence) stretches from late Pre-Cambrian to Upper Devonian times and reaches its climax in the Ny Friesland orogeny (between mid-Ordovician and late Silurian) and the structures arising therefrom form the core of this paper as they do of the region itself. The sequence is compared with that in other areas, particularly East Greenland.

Seafloor expression and shallow structure of a fold-and-thrust system, Isfjorden, west Spitsbergen

“…The construction of an almost continuous late Palaeozoic to early Tertiary sedimentary succession took place due to submergence of Svalbard during most of its geological evolution (Hjelle 1993). Igneous and metamorphic basement rocks on Spitsbergen are Precambrian to Silurian in age and were intensely deformed during the Caledonian Orogeny (Harland 1959(Harland , 1985Birkenmajer 1975;Ohta 1992;Fossen et al 2008;Gee et al 2008). Subsequently, the Svalbard area underwent several periods of erosion, Fig.…”

The Polarisbreen Series and other evidences of late Pre-Cambrian Ice Ages in Spitsbergen

“…The larger grains tend to be more rounded, so that a hand specimen gives the impression of a well-graded sandstone set in a dark base. In some specimens the sorting is remarkably good and in one all the quartz Map of Eastern Ny Friesland and Western Olav V Land to show diagrammatically the distribution of the Polarisbreen Series, based on the authors' surveys (Harland 1959) and Kulling (1934). The fine stipple marks the position of rock amongst ice.…”

Proto-basement in Svalbard

“…All candidate rocks were certainly tectonised in midPaleozoic, mainly Silurian time, Gee & Page 1994) and the methods of dating were not sufficient, until recently, to demonstrate basement material within the sequence (Gee et al 1992;Balashov et al 1993). Since Harland (1941) it was known that thrust and nappe structure was dominant, that many layers could be thrust slices and that this structure was imparted during the Caledonian Ny Friesland Orogeny (Harland 1959). To reconcile these observations with the consistency of the stratigraphic sequence throughout most of the metamorphic terrane it has been supposed that the lithostratigraphic units were sufficiently thick for the tectonism to affect the detail but not the overall sequence.…”

“…Tyrrell 1922 andFairbairn 1933). On the other hand Harland & Wilson (1956) outlined the first comprehensive sequence and map (Harland 1959;Harland et al 1966) of Ny Friesland without any major stratigraphic break. In the absence of conflicting evidence this interpretation had since been generally followed until lately.…”