Caledonian and Ellesmerian tectonism in northern Greenland, and their implications for the Wandel Sea Basin

Two Palaeozoic foldbelts, the North Greenland Foldbelt and the East Greenland Caledonides, meet in the northern part of Greenland. In the majority of published interpretations, these foldbelts are considered to be separate entities, caused by different events at different times: the E-W trending North Greenland Foldbelt is considered to be the product of the Middle/Late Devonian to Mississippian (early Carboniferous) Ellesmerian Orogeny; the N-S to NE-SW trending East Greenland Caledonides are part of the predominantly Silurian Caledonian Orogen. Establishing the relationship between the two foldbelts is important because the region where they intersect is overlain by late Paleozoic and younger sediments of the NW-SE trending Wandel Sea Basin.

Four principal lines of evidence have been used by previous workers to support a post-Caledonian, Ellesmerian age for deformation in the North Greenland Foldbelt: (1) age constraints provided by the youngest deformed strata and oldest undeformed strata; (2) the occurrence of easterly-derived Silurian turbidites thought to be derived from the Caledonides within the folded succession; (3) analogy with deformation in Ellesmere Island which appears to be a continuation of that in the North Greenland Foldbelt; (4) limited Rb-Sr isotopic data published 30 years ago. A GIS database of structural data, geological maps and related information compiled to test this evidence has revealed that there are, in fact, no data currently available anywhere in North Greenland which unequivocally demonstrate that Middle/Late Devonian to early Carboniferous (Ellesmerian) deformation has taken place. In many areas of the North Greenland Foldbelt, deformation could be late Silurian to Early Devonian, synchronous with the Caledonian deformation phase. Paradoxically, it is only in the East Greenland Caledonides that isotopic data record a tectonometamorphic event equivalent in age to the Ellesmerian Orogeny.

Evidence from North Greenland supports an interpretation in which the Caledonian Orogeny and Ellesmerian deformation represent a continuum of compressional events. We conclude that the current distinction between the North Greenland Foldbelt and the East Greenland Caledonides in the literature is misleading, and make a number of arguments that support a connection between the two belts in northeasternmost Greenland, and on which the Wandel Sea Basin has subsequently developed.