VENDIAN BASIN EVOLUTION IN EAST GREENLAND AND NE SVALBARD

In order to help focus new biostratigraphic and chemostratigraphic wor k, the sedimentology and stratigraphy of Vendian successions in centra l East Greenland and NE Svalbard (NE Spitsbergen and Nordaustlandet) a re reviewed. These areas originally formed part of a contiguous sedime ntary basin as illustrated by comparison of two measured sections, 750 m thick, in which a number of matching divisions occur. At the base, a carbonate platform succession (''bed-group 20'' in Greenland, Elbobr een Formation member E1 in Spitsbergen) is followed by two discrete gl acial facies associations separated by non-glacial sediments (Ulveso, Arena and Storeelv Formations of Greenland and members E2, E3-E4 and t he Wilsonbreen Formation of Spitsbergen), and a transgressive shale su ccession (Canyon Formation and Dracoisen Formation, respectively) with basal dolostone. Whereas NE Spitsbergen displays a further 300 m of s ection within the Dracoisen Formation, mostly of probable playa lake f acies, in Greenland a 50-m-scale regressive dolostone unit (upper Cany on Formation) is capped by only 20 m of lacustrine facies (Spiral Cree k Formation). In each case, lower Cambrian sandstones rest on the Vend ian sections. Later Vendian times (Ediacaran interval) seem to be virt ually unrepresented by marine strata. Reconstruction of the stratigrap hic architecture along the 180 km N-S outcrop belt in NE Svalbard and the 300 km N-S belt in East Greenland reveals few lateral changes beca use of an orientation nearly parallel to the depositional strike. Syn- depositional faulting apparently controlled accelerated subsidence in the East Greenland area, leading to the development of carbonate slope facies (''bed-group 19''), either overlain locally by ''bed-group 20' ', or conformably overlain by glacimarine deposits. A section towards the southeastern limit of the basin in East Greenland, in Canning Land , shows the glacigenic Storeelv Formation resting on a major erosion s urface on platform carbonates. In the far southwest, it rests directly on basement; this represents the main source area of sediments in the basin. The upper Canyon Formation shows evidence of progradation from the south. Chronostratigraphic interpretation of the succession leads us to the belief that the base of each glacial unit represents a sequ ence boundary, although only limited erosion occurred within the main outcrop belt. A sequence boundary may also be present at the base of t he Eibobreen Formation. Submarine erosion must have led to a slight hi atus at the close of the second glaciation, temporally following but s patially coincident with a sequence boundary. The upper Canyon Formati on is probably a highstand systems tract and the overlying base of the Spiral Creek Formation is a sequence boundary. The transgressive base of the Cambrian sandstones overprints another sequence boundary, at l east in Greenland.