Abstract The northeastern margin of Laurentia formed an important part of the Iapetus Ocean and includes the development of the Franklinian Basin in North Greenland and Arctic Canada. The uninterrupted continental margin bordering the North American craton is represented by well-exposed successions in Northeast and eastern North Greenland, together with Svalbard and Bjørnøya. Physiographically, the northeastern margin of Laurentia during the early Paleozoic history of Greenland was a northward extension of the passive rifted continental margin of the Caledonian continental edge of Laurentia. It was a transform-rifted margin and represents the part of the Laurentian margin that borders the Arctic part of the North Atlantic Ocean. Geologically, the northwestern segment of the continental margin has a somewhat different setting and development from farther south in the Northeast Greenland–Svalbard segment but both regions overlie a thick and extensive package of Neoproterozoic rocks and were affected by the Caledonian orogeny.

Abstract The Neoproterozoic succession of East and North-East Greenland (over 14 000 m thick) includes the Eleonore Bay Supergroup (?Tonian–Cryogenian) and the Tillite Group (Cryogenian–Ediacaran). The upper units of the Eleonore Bay Supergroup consist of shallow to deeper-water carbonates, succeeded by siliciclastic fine-grained sediments (Bedgroup 19) that characterize the top unit of the supergroup. The Tillite Group includes two diamictite-bearing units (Ulvesø and Storeelv formations) of glaciogenic origin and two upper, upwards-shallowing strata (Canyon and Spiral Creek formations) that were deposited during semiarid conditions and concluded the Neoproterozoic depositional cycle. Diamictite is preserved on the craton and compares with the Storeelv Formation (Fm.) of the Tillite Group. Detailed investigations of the diamictite-bearing units (i.e. Ulvesø and Storeelv formations) demonstrate that the lower of the two formations is mainly of marine origin, whereas the upper one has both marine and terrestrial origins. Chemostratigraphic data include analyses on total carbon (TC), total organic carbon (TOC), total sulphur (TS) and δ 13 C. The data set for δ 13 C shows a substantial and abrupt shift towards negative values of ≥10%, from below Bedgroup 19. Low-diversity acritarch assemblages (Cryogenian) are recorded from the Andrée Land and Tillite groups; a thin cherty dolostone unit present above the Storeelv Fm. suggests that the diamictite units are of late Cryogenian age and the upper part of the Tillite Group is Ediacaran. Bedgroup 19 disconformably overlies older carbonates and the unit is a prelude to the succeeding (upper Cryogenian–lower Ediacaran) diamictite sediments of the Tillite Group. A disconformity separates the Tillite Group from the overlying Lower Palaeozoic sediments. Both disconformities are, according to palaeomagnetic data, related to rift–drift episodes that occurred during the late Neoproterozoic. Alternatively, the isotope data suggest that the diamictites were deposited during the late Cryogenian glaciation and the older disconformity may be interpreted as a significant gap developed by the lowering of sea level during an early Cryogenian glaciation.

Sensitive high-resolution ion microprobe (SHRIMP) U-Pb ages have been obtained from zircons separated from Upper Carboniferous to Lower Permian SiO 2 -rich volcanic and subvolcanic rocks of eleven drill sites. The volcanic rocks belong to a large volcanic province that formed during the initial stage of the Central European Basin System. Two drill sites are located in Denmark (North Sea and Lolland), five in northern Germany, and four in western Poland. Apart from establishing the emplacement age of the volcanic units, the focus of the present study was the dating of inherited zircons. They give information about the chronostratigraphic structure of the anatectic component of the hybrid intraplate magmas, that is, the crust below the Central European Basin System. The Central European Basin System substrate consists mainly of a little known, covered terrane called Far Eastern Avalonia. The northern margin of the Central European Basin System rests on the collisional suture of Avalonia with Laurentia and Baltica. The southern margin is superposed on the Variscan orogen, which formed as a result of the Carboniferous collision of the Armorican Terrane Assemblage with Laurussia/Old Red continent. Where possible, a minimum of ten analyses has been used to calculate the emplacement age for each sample, which range between 290 and 303 Ma. The two Danish samples yielded only a small zircon population with a similar, but poorly constrained emplacement age. These results, together with the data of a precursor project ( Breitkreuz and Kennedy, 1999 ) indicate a remarkable synchronicity of the magmatic activity focused between 295 and 299 Ma throughout the Central European Basin System. Most zircon separates contain inherited grains or old cores. About seventy analyses, including data from the precursor study, are presumed to represent Avalonia and subordinately southern Baltica crust. The ages range from 320 to 2614 Ma. Paleozoic ages fall within the range of the Caledonian and Variscan orogenies. The Precambrian ages show two maxima, one between 1400 and 1600 Ma with a peak at 1450 Ma, and one between 750 and 1200 Ma with a peak at 1050 Ma. This age distribution strongly indicates an affiliation of the sub-Central European Basin System crust to Avalonia and an original position adjacent to the Amazonian craton.