Pre-Devonian landscape of the Baltic Oil-Shale Basin, NW of the Russian Platform, 1999, Puura Vaino, Vaher Rein, Tuuling Igor,

The erosional relief of Ordovician and Silurian deposits in Estonia was developed during the continental period in late Silurian and early-middle Devonian times. The uplift of the area and marine regression were induced by compressional tectonics in the continental interior related to the closure of the Iapetus and Tornqvist Oceans. In the northern part of the Baltic sedimentary basin (Estonia), on the gentle southerly dipping slope between the Fennoscandian Shield (Finland) and Baltic Syneclise (Latvia), a pre-Devonian, slightly rugged erosional relief with few cuesta was developed. The pre-Devonian erosional landforms -- hills, depressions and escarpments reaching 150 m in height -- were probably buried under the Devonian deposits and then partly re-exposed by pre-Quaternary erosion. These landforms are described in detail using data from several thousands of cores drilled in the course of oil-shale and phosphorite exploration and mining

Palaeokarst systems in the Neoproterozoic of eastern North Greenland in relation to extensional tectonics on the Laurentian margin, 1999, Smith M. P. , Soper N. J. , Higgins A. K. , Rasmussen J. A. , Craig L. E. ,

Palaeokarst, in the form of large, uncollapsed cave systems, is described from the Proterozoic of Kronprins Christian Land, eastern North Greenland. The endokarst, of entirely meteoric origin, is developed in dolostones of the Fyns So Formation (Hagen Fjord Group, Riphean). At one locality, Hjornegletscher, shallow, sub-horizontal phreatic conduits are present below an unconformity surface and are infilled by the overlying Ediacaran Kap Holbaek Formation. In Saefaxi Elv, the unconformity is overlain by the Wandel Valley Formation, an Early Ordovician carbonate sequence that is widely transgressive over northeastern Greenland. Vertical vadose fissures extend down towards the phreas, but the cave systems are again filled by Kap Holbaek Formation sediments. At Hjornegletscher, channels up to 40 m wide incise the phreatic system, pointing to relative base-lever lowering before, or during, deposition of the Kap Holbaek Formation. Recognition of a depositional hiatus between the Fyns So and Kap Holbaek formations, in what was previously thought to be a continuous Vendian Hagen Fjord sequence, has implications for regional correlation and tectonics. The unconformity could represent most of Vendian time, accounting for the absence, in this area, of glaciogenic sedimentary rocks in the Hagen Fjord Group. This permits correlation of the Fyns So Formation with other end-Riphean transgressive carbonate sequences developed in East Greenland, Svalbard and perhaps Scotland, that represent the culmination of a major pre-Iapetan rift-sag cycle. Secondly, recognition of the scale of the sub-Wandel Valley unconformity points to regional uplift and tilting of northeastern Greenland in mid-Cambrian to earliest Ordovician time. This must represent a phase of renewed extension of the Iapetus passive margin that is unique to this corner of Laurentia, not terrane collision as previously suggested