Neoproterozoic-Lower Palaeozoic stratigraphical relationships in the marginal thin-skinned thrust belt of the East Greenland Caledonides: comparisonswith the foreland in Scotland

Throughout the 1300 km long East Greenland Caledonides, the western exposed marginal thrusts overlie foreland rocks of latest Neoproterozoic-Early Pal aeozoic age, mainly exposed in tectonic windows. In the western, 100-130 km wide, marginal thrust belt, the thrust planes outlining the windows appear to follow long flats developed in Lower Palaeozoic carbonates. East of the marginal thrust belt, thrust inclinations steepen, and by implication the remaining part of the Caledonian orogen extending eastwards to the present Atlantic Ocean coast is allochthonous and thick-skinned. The contrast betwe en the restricted Neoproterozoic-Lower Palaeozoic foreland succession and t he very thick and almost continuous sedimentation of the allochthonsus Neop rotetozoic Eleonore Bay Supergroup-Tillite Group-Cambro-Ordovician sequence of the fjord zone of East Greenland confirms the presence of distinct N-S trending facies belts on the northwestern passive margin of Iapetus. Compar isons with the Caledonides of Northwest Scotland, which may originally have lain as little as 500 km south of the East Greenland Caledonides, provide further clues to the understanding of Neoproterozoic-Early Palaeozaic basin geometry on this sector of the developing Iapetus margin. The areas of the Laurentian margin represented in the foreland windows of East Greenland we re inboard of Neoproterozoic rifting but, with respect to the Torridonian b asins of Northwest Scotland, the Eleonore Bag. Supergroup succession must h ave been laid down further outboard. Similarly the Lower Palaeozoic develop ments of the foreland of Northwest Scotland are thicker than the equivalent foreland sequences of East Greenland, but much thinner than the allochthon ous East Greenland Cambro-Ordovician succession.