Abstract The Greenland and Svalbard Caledonides make up an important part of the Palaeozoic Caledonian orogen, and preserve a complex history of Palaeoproterozoic arc accretion, Proterozoic to Palaeozoic sedimentation within various basins and extensive magmatism, metamorphism and deformation during the Caledonian orogeny. In this summary, the current understanding of the structure and lithological content of the Greenland and Svalbard Caledonides is first reviewed, and open questions are highlighted. The Greenland Caledonides are divided into three different segments, and the term terrane is abandoned for the Svalbard Caledonides. Then, other Caledonian fragments in the Arctic region are discussed, including Bjørnøya, Pearya and Cordilleran terranes and parts of the Barents Shelf. Finally, a regional synthesis covering the geological evolution of the Greenland and Svalbard Caledonides from the Palaeoproterozoic to the end of the Caledonian orogeny is presented and controversial issues and open questions are discussed.

The Iapetus margin of Laurentia is preserved, with varying degrees of deformation, along a belt that extends for 1300 km along the eastern coast of Greenland, from Scoresby Sund in the south to Kronprins Christian Land at the northernmost extent of the Caledonian–Appalachian orogen. Along the length of the Greenland Caledonides, deformation is restricted to a single orogenic phase, the Scandian, at around 425 Ma, which represents the continent-continent collision of Laurentia and Baltica. The Lower Paleozoic stratigraphy can be closely correlated with the palinspastically contiguous terranes of NE Spitsbergen, Bjørnøya, and NW Scotland, and, farther to the south, that of western Newfoundland. In Greenland itself, Lower Paleozoic sediments are present in the foreland, parautochthon, and the highest allochthonous sheet of the orogen, the Franz Joseph allochthon. In the Franklinian Basin of eastern North Greenland, unconformity-bounded Lower Cambrian sediments can be correlated with the Sauk I sequence of cratonic North America. These Cambrian sediments are separated from younger units by a significant hiatus, the sub–Wandel Valley unconformity, but above that surface, the succession extends without major breaks from the major flooding event at the base of Sauk IV (Early Ordovician) through to the early Wenlock. The carbonate platform in this region foundered from late Llandovery time onward due to loading by thrust sheets, and turbidite deposition replaced platform carbonate deposition. Caledonian thrusts truncate the youngest preserved sediments, which are of early Wenlock age. The punctuated, attenuated stratigraphy seen in Kronprins Christian Land continues southward along the length of the parautochthon, through Lambert Land, Nørreland, and Dronning Louise Land, to a series of tectonic windows in the southern part of the Greenland Caledonides. In contrast to the stratigraphy seen in the parautochthon, the Franz Joseph allochthon contains one of the thickest Cambrian–Middle Ordovician successions in Laurentia, including a complete succession from Sauk I to Tippecanoe II.

Abstract The last decade of structural and isotope-age dating studies in Svalbard and East Greenland has provided strong support for the close correlation of these segments of the Caledonide Orogen, as had previously been inferred from stratigraphic evidence. Prior to Tertiary opening of the Norweigan–Greenland Sea, Svalbard's Caledonian terranes were an essential part of the Laurentian margin, as witnessed not only by the Early Palaeozoic depositional environments and fauna, but also by the character of the Palaeoproterozoic basement, the Meso- to Neoproterozoic cover, the evidence of late Grenvillian tectono-thermal activity, Caledonian structural style and timing of movements, Caledonian granitic magmatism and Old Red Sandstone (ORS) deposition. Recently published maps of East Greenland show the hinterland allochthons of central East Greenland to strike out obliquely into the continental shelf. The hypothesis promoted here requires that they continue offshore northwards, extending to the northern edge of the NE Greenland shelf and that most of the Svalbard terranes were northerly continuations of the East Greenland Caledonides. Only along the west coast of central Spitsbergen are ‘foreign’ terranes exposed that have affinity with Pearya, having been located north of the North Greenland foldbelt, apparently unrelated to Laurentia, prior to Ellesmerian Orogeny. The unambiguous affinity of the Svalbardian and Greenlandian (Laurentian) Caledonides contrasts markedly with the Timanide evolution of northeastern Baltica. It confirms previous interpretations that an important Caledonian suture-zone transgresses northeast-wards across the Barents Sea, separating Laurentian domains in the NW from the Timanides of Baltica in the SE. The Timanides of northeastern Europe are truncated by, and terminate in the Barentsian Caledonides of the Barents Shelf.

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 This chapter describes and presents a newly compiled map illustrating the paleogeography of Laurentia during the earliest Ordovician, a time when the great American carbonate bank was at one of its greatest extents and a period for which the most is understood. The map depicts the known or postulated extent of the inner detrital belt, the great American carbonate bank and the more problematic (commonly structurally relocated) outer detrital belt. The period on which the map is based and discussed in the accompanying text is based on the Early Ordovician (early Ibexian) (early Tremadocian) Stonehenge transgression.

Abstract New palaeogeographical reconstructions are presented at 10 myr intervals from the Lower Cambrian at 540 Ma to the Lower Devonian at 400 Ma, showing continental crustal fragments and oceans (not lands and seas), with appropriate kinematic continuity between successive maps. The maps were chiefly generated by revised and selected palaeomagnetic data and revised Apparent Polar Wandering paths linked to present-day polygons from the main continents. These have been reinforced by analysis of the distributions of some fossils and sediments. Gondwana was the dominating supercontinent from its final assembly in the Latest Neoproterozoic at about 550 Ma until the Carboniferous, and covered much of the Southern Hemisphere. The Northern Hemisphere was largely occupied by the vast Panthalassic Ocean. The relative positions of the major continents and the latitudes and rotation histories of Gondwana, Baltica, Siberia and Laurentia (Laurussia from the mid-Silurian) are now well known. Although Laurentia was oriented in a similar direction to the present, Siberia was inverted throughout the Lower Palaeozoic, and Baltica too was initially inverted, but rotated through 120° between the Late Cambrian and Late Ordovician before collision with Laurentia in the mid-Silurian Caledonide Orogeny. Through reconstructions of the Caledonide and some other orogenies, the progressive history of the Iapetus Ocean between Laurentia and Baltica/Gondwana is well constrained. Less major continents whose positions are also well known include Avalonia (initially peri-Gondwanan but migrating in the Early Ordovician to join Baltica by the end of the Ordovician), Sibumasu (now considered an integral part of Gondwana) and Mongolia (adjacent to Siberia). A large number of other terranes are reviewed and plotted on the reconstructions with varying degrees of certainty. However, significant continents with less well constrained or controversial positions are South China, North China (Sinokorea), Annamia (Indochina) and Arctic Alaska–Chukotka. The European areas of France, Iberia and southern Italy, previously considered by some as a separate Armorican Terrane Assemblage, remained parts of core Gondwana until the opening of the Palaeotethys Ocean near the end of the Silurian, but it is uncertain whether Perunica (Bohemia) was one of that group or whether it left Gondwana during the Middle Ordovician.

Abstract A succession of palaeogeographical reconstructions is presented, covering half the globe and the time interval from the latest Proterozoic (Vendian) at 550 Ma to the end of the Palaeozoic (latest Permian) at 250 Ma, mostly at 20 or 30 Ma intervals. The various terranes that today constitute Europe are defined and their margins discussed briefly; these are Gondwana, Avalonia, the Rheno-Hercynian Terrane, the Armorican Terrane Assemblage, Perunica, Apulia, Adria, the Hellenic Terrane (including Moesia), Laurentia, and Baltica. As time elapsed, many of these terranes combined to form first Laurussia and subsequently Pangaea. The further terranes of Siberia and Kara adjoined Europe and were relevant to its Palaeozoic development. Brief sections are included on the individual history and geography of the Vendian and the six Palaeozoic systems, with emphasis on their importance in the building of Europe.

Abstract The biogeographical distribution of Ordovician and Silurian gastropods, monoplacophorans and mimospirids has been analysed on a generic level. The dataset contains 334 genera and 2769 species, yielding 1231 records of genera with 2274 occurrences worldwide. There is a bias towards eastern Laurentia, Baltica and Perunica records. Some 53.1% of the records are Ordovician. The study demonstrates that these molluscs are well suited to being used to improve understanding of Ordovician and Silurian biogeographical provinciality. Specific points are that: a Lower Ordovician assemblage is evident in Laurentia; the fauna of the Argentinean Precordillera is Laurentian until the Darriwilian, when taxa are shared with North China; Late Silurian gastropods from the Alexander terrane (SE Alaska) are unknown in Laurentia, but support a rift origin of this terrane from NE Siberia; Perunica, Ibero-Armorica and Morocco cluster together throughout the Ordovician but Perunica and Morocco are closer; Darriwilian–Sandbian deep-water Bohemian taxa occur in Baltica; a Laurentian–Baltica proximity is unsupported until the Silurian; Siberia clusters with North China and eastern Laurentia during the Tremadocian–Darriwilian; during the Gorstian–Pridoli Siberia clusters with the Farewell and Alexander terranes; North China may have been close to Laurentia and the Argentinean margin of Gondwana; and the affinity of Tarim taxa is problematic.