Wandel Sea Research Articles

Tectonic inversion in the Wandel Sea Basin: A new structural model of Kilen (eastern North Greenland)

The seminunatak Kilen in eastern North Greenland, with its complexly deformed Carboniferous-Cretaceous strata, is a key area to understand the tectonic history of the transform plate boundary between eastern North Greenland and Svalbard. Detailed 3-D geological mapping from oblique photogrammetry along with limited ground fieldwork and interpretation of previously published data forms the basis for a new structural model of Kilen. Previous structural models interpreted rhombic-shaped fault patterns as the evidence for strike-slip tectonics. These structures are here interpreted to be the result of a post-Coniacian NE-SW extension with NW-SE trending normal faults followed by later, N-S compression of presumable Paleocene-Eocene age, folding the faults passively and suggesting the presence of a basal detachment. Furthermore, two thrust sheets have been distinguished on Kilen: a lower Kilen Thrust Sheet and an upper Hondal Elv Thrust Sheet separated by a subhorizontal fault: the Central Detachment. The style of deformation and the structures described are interpreted as the result of Paleocene-Eocene N-S directed compression resulting in basin inversion with strike-slip faults only having minor status. This indicates that the Greenland margin as exposed on Kilen and the conjugate Svalbard margin in the West Spitsbergen fold-and-thrust belt are more similar than previously anticipated.

Carboniferous basin in Holm Land records local exhumation of the North-East Greenland Caledonides: Implications for the detrital zircon signature of a collisional orogen

Carboniferous strata of the Wandel Sea Basin unconformably overlie the Laurentian Precambrian crystalline rocks of the Caledonian hinterland at its northernmost exposures in Holm Land (∼80°N). Complex zircon from an intermediate gneiss gives an upper-intercept age of 1878 ± 71 Ma, a protolith age which fits with the regional 1.8–2.0 Ga calc-alkaline arc. A strongly deformed pegmatite was intruded at 435 ± 17 Ma, and it is a rare example of Caledonian magmatism in the northern sector of the orogen. Omphacite confirms the presence of eclogite (sensu stricto) lenses in the basement complex, thus documenting the northern extent of the North-East Greenland eclogite province formed during the Caledonian collision with Baltica. Holm Land lies in the eastern block of the eclogite province, where an ultrahigh-pressure (UHP) metamorphic event took place at 365–350 Ma. Zircon from a Holm Land eclogite lacks a Eu anomaly, has a flat heavy rare earth element pattern, and gives a sensitive high-resolution ion microprobe U-Pb age of 423 ± 7 Ma, and it is thus interpreted as the time of high-pressure (HP) metamorphism. This age overlaps with the established age of widespread HP metamorphism for the eclogite province (i.e., 415–395 Ma), rather than the younger UHP metamorphism. Westward thrusting of the North-East Greenland eclogite province onto the Laurentian margin after 395 Ma and subsequent exhumation of this uppermost thrust sheet provided a substrate for Carboniferous deposition. Detrital zircon age spectra from arkosic sandstones of the late Visean (ca. 330–340 Ma) Sortebakker and early Moscovian (ca. 310–315 Ma) Kap Jungersen Formations record the progressive unroofing of the North-East Greenland Caledonides. All seven samples have a major peak at 1.8–2.0 Ga, and five also have a 1.75 Ga peak, matching the Paleoproterozoic arc and later anorogenic granitoids that comprise the crystalline basement. Paleozoic grains are sparse in the Sortebakker sandstones, but they constitute a pronounced 400 Ma peak in the younger Kap Jungersen Formation. The composition of the detritus—including garnet clasts, the high amount of discordant zircon (40%), and the large numbers of grains with metamorphic rims that cluster around 410 Ma—reflects a local provenance sourced in the North-East Greenland eclogite province, with some input from the overlying thrust sheets. Other Devonian and Carboniferous basins within and peripheral to the Caledonides also show distinct signatures, demonstrating that there is not a simple, representative detrital zircon signature for the Caledonian orogen.

Des​criptive text to the Geological map of Greenland, 1:500 000, Lambert Land, Sheet 9

The Lambert Land 1:500 000 scale geological map sheet covers a segment of the East Greenland Caledonian orogen extending between latitudes 78°–81°N and longitudes 13°–29°W. The region was geologically mapped in the summers of 1978–1980 and 1993–1995 as part of a regional Survey mapping programme, and the map sheet was printed in 2000. The region covered by the Lambert Land map sheet comprises a northern segment of the East Greenland Caledonides that is in thrust contact with the Caledonian foreland. The contact is an Edipping, NNE–SSW-trending thrust that runs through Kronprins Christian Land from west of Blåsø in the south to the region east of Sjælland Fjelde in the north. The Caledonian foreland succession is exposed in Mylius-Erichsen Land and Amdrup Højland on the west side of Danmark Fjord, and in western Kronprins Christian Land on the east side of Danmark Fjord. The several kilometre thick foreland succession ranges in age from Palaeoproterozoic to Silurian. In western Kronprins Christian Land the undeformed Ordovician–Silurian carbonates of the foreland pass eastwards into the so-called Thinskinned fold-and-thrust belt developed in the same strata that farther eastwards are structurally overlain by the allochthonous Vandredalen thrust sheet. This thrust sheet is in its turn overlain by a group of thrust sheets that make up the mountainous high ground of central parts of Kronprins Christian Land, and structurally form the so-called Western thrust belt; these rock units have a deeper crustal origin. In the extreme east the Nørreland thrust sheet is exposed in a coastal strip that comprises Palaeoproterozoic crystalline gneisses that include eclogite-facies enclaves and units of meta-igneous and metasedimentary rocks.
 Post-Caledonian rocks crop out in the north-eastern coastal parts of the map sheet area, and include sedimentary rocks of early Carboniferous to late Jurassic age that form part of the Wandel Sea Basin succession. Undifferentiated Quaternary deposits, ground moraine, alluvial fans and talus are distinguished where they obscure significant areas of bedrock.

Des​criptive text to the Geological map of Greenland, 1:500 000, Lambert Land, Sheet 9

NOTE: This Map Description was published in a former series of GEUS Bulletin. Please use the original series name when citing this series, for example: Higgins, A. K. (2015). Des​criptive text to the Geological map of Greenland, 1:500 000, Lambert Land, Sheet 9. Geological Survey of Denmark and Greenland Map Series 7, 1-29. https://doi.org/10.34194/geusm.v7.4563 _______________ The Lambert Land 1:500 000 scale geological map sheet covers a segment of the East Greenland Caledonian orogen extending between latitudes 78°–81°N and longitudes 13°–29°W. The region was geologically mapped in the summers of 1978–1980 and 1993–1995 as part of a regional Survey mapping programme, and the map sheet was printed in 2000. The region covered by the Lambert Land map sheet comprises a northern segment of the East Greenland Caledonides that is in thrust contact with the Caledonian foreland. The contact is an Edipping, NNE–SSW-trending thrust that runs through Kronprins Christian Land from west of Blaso in the south to the region east of Sjaelland Fjelde in the north. The Caledonian foreland succession is exposed in Mylius-Erichsen Land and Amdrup Hojland on the west side of Danmark Fjord, and in western Kronprins Christian Land on the east side of Danmark Fjord. The several kilometre thick foreland succession ranges in age from Palaeoproterozoic to Silurian. In western Kronprins Christian Land the undeformed Ordovician–Silurian carbonates of the foreland pass eastwards into the so-called Thinskinned fold-and-thrust belt developed in the same strata that farther eastwards are structurally overlain by the allochthonous Vandredalen thrust sheet. This thrust sheet is in its turn overlain by a group of thrust sheets that make up the mountainous high ground of central parts of Kronprins Christian Land, and structurally form the so-called Western thrust belt; these rock units have a deeper crustal origin. In the extreme east the Norreland thrust sheet is exposed in a coastal strip that comprises Palaeoproterozoic crystalline gneisses that include eclogite-facies enclaves and units of meta-igneous and metasedimentary rocks. Post-Caledonian rocks crop out in the north-eastern coastal parts of the map sheet area, and include sedimentary rocks of early Carboniferous to late Jurassic age that form part of the Wandel Sea Basin succession. Undifferentiated Quaternary deposits, ground moraine, alluvial fans and talus are distinguished where they obscure significant areas of bedrock.

A healed strike-slip plate boundary in North Greenland indicated through associated pull-apart basins

Abstract In the North Atlantic, Laurentia–Eurasia break-up commenced in the Late Carboniferous, largely following the structural grain of the Caledonian Fold Belt. However, in the Arctic region, a 45° offset in the plate boundary between North Greenland and Svalbard was determined by a number of pre-Caledonian fundamental faults in North Greenland. As a result, this segment of the plate boundary experienced significant episodes of combined transtension and transpression, in part controlled by the movement of a temporarily independent Greenland Plate. Late Permian–Mesozoic deposits in the North Greenland Wandel Sea Basin record the plate-boundary history along this offset, in our view in a series of at least 20, variously disturbed, pull-apart basins, most of which can be assigned to four major episodes of pull-apart basin formation. The direction of the pre-existing fundamental faults, in combination with the regional variation in rock properties of both the basin floor and basin fill, explains the marked differences in tectonic style recorded along the plate boundary.

Detrital zircon characteristics of the Lower Cretaceous Isachsen Formation, Sverdrup Basin: source constraints from age and Hf isotope data

Detrital zircons from the Lower Cretaceous Isachsen Formation of the Sverdrup Basin, Canadian Arctic Archipelago, have been dated by the U–Pb method and analyzed for Hf isotopes by laser ablation microprobe – inductively coupled plasma – mass spectrometry (LAM–ICP–MS). Five samples from four locations on Ellesmere and Axel Heiberg islands display similar ranges of U–Pb ages, with significant zircon populations at 2.8–2.6, 1.9–1.8, 1.7–1.6, and 1.2–1.0 Ga. Major hiatuses occur between 2.4 and 2.0 Ga and from 0.96 to 0.5 Ga. Low initial εHfvalues indicating recycled crust components are significant in Palaeoproterozoic (1.9–1.8 Ga) and Neoarchaean (2.8–2.6 Ga) zircon populations. Other U–Pb age populations in the studied samples are dominated by zircon with positive εHfvalues, indicating a significant contribution from mantle-derived protoliths. The εHfvalues seen within a given U–Pb age population are generally consistent, with only minor scatter among the different samples. U–Pb and Hf data closely resemble previously published data from Lower Cretaceous rocks in northern Greenland, suggesting they have the same origin. The data are also largely consistent with the East Greenland Caledonides and the Precambrian basement of Greenland and northern Canada as predominant sources of zircon for the studied sandstones. However, based on the level of similarity between data from the Wandel Sea Basin and Sverdrup Basin sediments and on previous Nd isotope work in the Sverdrup Basin, it is likely that the sediments represent redeposited lower and middle Palaeozoic sediments.

Segmentation of the eastern North Greenland oblique-shear margin — Regional plate tectonic implications

Late Cenozoic opening of the Fram Strait led to formation of the NW–SE striking, eastern North Greenland oblique-shear margin at transition from the Norwegian–Greenland Sea to the SW Eurasia Basin. Onshore geology exposed on large peninsulas in front of the major Greenland Inland Ice reveals a highly complex, Paleozoic–early Cenozoic pre-opening setting. However, due to extreme ice conditions, very little is known about the offshore areas seawards of – and between – the peninsulas. Consequently, prevailing structural-tectonic models of the margin tend to be significantly oversimplified and inadequate. We present the first, combined onshore–offshore, model of the margin integrating onshore outcrops with potential field data, new offshore seismic reflection data and receiver-function analysis of seismic broad band data. The results reveal a margin which is far more complex than previously anticipated. In particular, we interpret strong margin segmentation along N/NE-striking fault structures. The structures are likely to have formed by Late Mesozoic–early Cenozoic strike-slip tectonics and have continued to be active during the late Cenozoic. A more than 8 km deep sedimentary basin is interpreted to underlie the central Wandel Sea, confined by these N/NE-striking structures. We suggest that similar margin segmentation affected the conjugate Yermak Plateau–North Svalbard margin as well as parts of the NE Greenland margin to the SE. Hence, the results have important implications for the general understanding of the Mesozoic–early Cenozoic development of the intra-continental De Geer Mega-shear Region between North Greenland and Eurasia.

Late glacial and Holocene marine records from the Independence Fjord and Wandel Sea regions, North Greenland

Late glacial and Holocene marine records from the Independence Fjord and Wandel Sea regions, North Greenland

Provenance of Lower Cretaceous sediments in the Wandel Sea Basin, North Greenland

Detrital zircons in Lower Cretaceous sedimentary formations from the Wandel Sea Basin (Kilen, Peary Land) were dated by U–Pb and analysed for Hf isotopes by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Samples from Kilen and Peary Land display a wide range of U–Pb ages, with significant zircon populations at 1.0–1.1 and 1.8–2.0 Ga. Major hiati occur between 2.1 and 2.4 and from 0.48 to 0.91 Ga. Low initial ϵ Hf values indicate that recycled crust components are significant in Caledonian-aged zircons, and in Palaeoproterozoic (1.8–2.0 Ga) and Neoarchaean zircon populations. Other U–Pb age populations in the studied samples are dominated by zircons with positive ϵ Hf values indicating a significant contribution of mantle-derived material in these periods. A narrow range of ϵ Hf values is commonly seen within a given U–Pb age population, and the values seen in the samples are in general correlated with the different age populations and their frequency. One exception is the 1.8–2.0 Ga population, where variations suggest variable sources. The U–Pb and Hf data are consistent with Greenland as the sole source of zircon from the studied sandstones.

Late glacial and Holocene marine records from the Independence Fjord and Wandel Sea regions, North Greenland

The first marine sediment cores from the unexplored Independence Fjord system and theWandel Sea, North Greenland, have been investigated to reveal the glacial marine history of the region. Two key sites in the Independence Fjord system, and an earlier analysed site from the Wandel Sea continental slope, off the mouth of Independence Fjord, are presented. The Independence Fjord sites reveal an early Holocene record (10.0–8.9 Kya) of fine-grained reddish muds with calcareous microfossils, dominated by the benthic foraminifera Cassidulina neoteretis. We suggest that a semi-permanent fast ice cover characterized the region in the early Holocene, and that the deeper troughs in the mouth region of the Independence Fjord system were intruded by subsurface Atlantic water. A stiff diamicton, at least 1.3 m thick, with coal and sandstone clasts of mainly local origin, and a 0.5-m-thick Holocene cover, are found in one of the sites. The diamicton is assumed to represent a subglacial till predating the early Holocene sediments (>10 Kya). Shallow seismic records off the mouth of Independence Fjord reveal kilometre-sized troughs with signs of glacial erosion, till deposition and a Holocene glaciomarine deposition. These features could indicate that glacial ice debouching from the Independence Fjord system at some time during the last glacial period extended to the mid-outer Wandel Sea shelf. Data from a high-resolution sediment core previously retrieved from the adjacent Wandel Sea slope indicate that the maximum ice sheet advance in this area culminated about 25–20 Kya.

Fusulinid zonation of the Upper Carboniferous Kap Jungersen and Foldedal Formations, southern Amdrup Land, eastern North Greenland

New fusulinid data from the Kap Jungersen and Foldedal Formations in southern Amdrup Land, eastern North Greenland allow the establishment of a detailed fusulinid-based zonation of the Upper Carboniferous succession in the Wandel Sea Basin. The fusulinid fauna is quite similar to that of the Russian Platform, the Ural Mountains, Spitsbergen, Bjørnøya, and the offshore areas of the Barents Sea, and therefore the Greenland strata are confidently correlated to the these regions. The Kap Jungersen Formation and the lower part of the Foldedal Formation are dated as late early Moscovian to latest Moscovian in age. The locally more than 450 m thick Moscovian part of the succession comprises four fusulinid zones: the Profusulinella prisca – Neostaffella subquadrata Zone and the Citrinoides paraozawai Zone of early Moscovian age, and the Fusulinella bocki – Pseduofusulinella pulchra Zone and the Protriticites ovatus Zone of late Moscovian age. Lower and middle Kasimovian deposits, characterized by two fusulinid assemblages of the Obsoletes obsoletus – Protriticites pseudomontiparus Zone and the Montiparus paramontiparus Zone, are recognised for the first time in Amdrup Land. The thin lower Gzelian succession is represented by two fusulinid assemblages that definine the Rugosofusulina flexuosa Zone and the Daixina crispa – Rauserites stuckenbergi Zone. The youngest Carboniferous strata, belonging to the Orenburgian part of the Gzelian are characterised by an assemblage of the Schellwienia ulukensis Zone.

Discussion on pre-ocean opening compression of the Northwestern Atlantic margin: evidence from eastern Greenland

Scientific editing by Nick Rogers. H. D. Maher Jr, S. Bergh & Alvar Braathen write: ⇓Manby & Lyberis (2000) argue for a Cretaceous–Palaeocene age and a convergent setting for both the fold structures of the Wandel Sea Basin and for the West Spitsbergen fold–thrust belt as an alternative to models of decoupling during Palaeocene–Eocene transpressive motions between Greenland and the Barents Shelf. In this context, we discuss evidence on the timing and kinematics of the West Spitsbergen fold–thrust belt, and constraints on the timing of deformation in the Wandel Sea Basin. Multiple lines of evidence constraining the timing of fold–thrust formation in Spitsbergen are discussed in ⇓Maher et al. (1995) and clearly indicate major fold-thrust development in the Palaeocene–Eocene. Space limitations prevent their description here. The nature of additional Late Cretaceous deformation on Spitsbergen is another question. It is partly constrained by the unconformity at the base of the Tertiary sequence, which is well exposed in many places and is consistently disconformable to the eye. This unconformity involves differential uplift to the north with a regional tilt of a degree or less, has a character inconsistent with previous fold-thrust development along the islands western margin, and can be related to a second pulse within the High Arctic Large Igneous Province (⇓Maher 2001). More recent work confirms a Palaeocene–Eocene age for the Spitsbergen contractional structures. Manby & Lyberis refer to ⇓Blythe & Kleinspehn (1998) as indicating a Late Cretaceous age for Spitsbergen fold–thrust belt uplift. In their summary figure Blythe & Kleinspehn indicate uplift and erosion of source terranes initiating at 70 Ma and continuing until c. 43 Ma. Six detailed thermal histories generated from track-length modelling of samples taken from the Tertiary foreland basin sediments provide particular insight. As the authors note, three samples with depositional ages of …

Polyphase deformation at the Harder Fjord Fault Zone (North Greenland)

In North Greenland, the E–W-trending Harder Fjord Fault Zone represents a major lineament which cuts through Cambrian to Silurian deep-water sediments of the Franklinian Basin over a distance of 300 km. On both sides of the fault zone, these successions were affected by two stages of folding (F1, F2) during Devonian to Early Carboniferous (Ellesmerian) deformation. No field evidence was found that the Harder Fjord Fault Zone was active prior to Ellesmerian folding. Early movements along the fault zone are indicated by post-Ellesmerian sedimentation of coarse red-beds (Depot Bugt conglomerate) which represent the oldest of the Wandel Sea Basin sediments. They were probably deposited in narrow, fault-controlled (?)Late Carboniferous basins similar to those described from Svalbard. During Late Cretaceous times, 500 m thick fluvial and marine clastic sediments were unconformably deposited over the folded Cambro-Ordovician units. Although no direct field evidence suggests that sedimentation was controlled by displacements along the Harder Fjord Fault Zone, the intrusion of Upper Cretaceous mafic sills and dykes indicates a phase of important crustal extension related to reactivation of the fault zone during this period of time. This stage was followed by post-late Santonian (Eurekan) N–S compression (D3) which affected the Franklinian Basin deposits, Wandel Sea Basin sediments and mafic intrusions. In general, it was concentrated along the Harder Fjord Fault Zone and probably caused the reactivation of pre-existing (?)Carboniferous and younger fault lines. The entire deformation and its timing are comparable with the Eurekan structures found at the Kap Cannon Thrust Zone in northernmost Greenland and are related to intracontinental compression prior to the separation of Svalbard from Greenland.

Palynology and deposition in the Wandel Sea Basin, eastern North Greenland

This collection of papers adds to the understanding of the stratigraphic, depositional and structural history of the Wandel Sea Basin in eastern North Greenland (Fig. 1). Most importantly, the ages of the initial (Carboniferous) and final (Palaeogene) depositional events are now much better constrained than previously, allowing correlation with the successions in East Greenland, Svalbard and the Barents Sea. The Wandel Sea Basin was an area of accumulation through the Early Carboniferous to the Palaeogene period, located at the margins of the stable Greenland craton where the Caledonian and Ellesmerian orogenic belts intersect (Fig. 1). Two main epochs of basin evolution have been recognised during previous studies of the basin fill: a Late Palaeozoic – Early Triassic epoch characterised by a fairly simple system of grabens and half-grabens, and a Mesozoic epoch dominated by strike-slip movements (Håkansson & Stemmerik 1989). The Mesozoic epoch only influenced that part of the basin north of the Trolle Land fault zone and its eastward extension (Fig. 1). Thus the northern and southern parts of the basin have very different structural and depositional histories, and accordingly different thermal histories and hydrocarbon potential as exemplified by the tectono-stratigraphic study of northern Amdrup Land by Stemmerik et al. (2000, this volume). This study shows that the Sommerterrasserne fault is the south-eastern extension of the Trolle Land fault zone, dividing Amdrup Land into two areas with different stratigraphic and structural histories. Sediments of the Upper Permian Midnatfjeld Formation are restricted to north-east of the Sommerterrasserne fault where they are conformably overlain by Upper Jurassic sediments. In this area the Carboniferous – Upper Jurassic succession is folded in broad domal folds with NE–SW-oriented axes, whereas the Upper Palaeozoic sediments are gently dipping south-west of the fault. Folding most likely took place during the latest Cretaceous correlating with compressional events that also affected the sedimentary basins at Kilen and Prinsesse Ingeborg Halvø further to the north in the Trolle Land fault zone.

Palynology and depositional history of the Paleocene? Thyra Ø Formation, Wandel Sea Basin, eastern North Greenland

The Thyra Ø Formation in eastern North Greenland has been dated as Late Paleocene to possibly earliest Eocene based on its content of palynomorphs. The palynomorph assemblage is dominated by long ranging taxa and reworked Upper Cretaceous species. The Late Paleocene age of the formation is based on the occurrence of Cerodinium speciosum and Spinidinium pilatum. However, the presence of Cerodinium markovae, Spinidinium sagittula, and ?Ilexpollenites sp. suggests that the formation may range into the earliest Eocene.

Carboniferous algal microflora, Kap Jungersen and Foldedal Formations, Holm Land and Amdrup Land, eastern North Greenland

A diverse assemblage of calcareous algae was recorded from the Moscovian–Gzelian Kap Jungersen and Foldedal Formations in Amdrup Land and Holm Land. The flora, consisting of 25 species, is dominated by rhodophytes and chlorophytes, most of them similar to or identical with species previously recognised in the Sverdrup Basin of Arctic Canada. One new genus and species, Groenlandella enigmatica n.gen. et n.sp., has been erected and is apparently endemic to the Wandel Sea Basin. The composition of the Greenland algal flora indicates that it belongs to the Uraloporella flora of the present-day northern hemisphere (Arctic Canada, Svalbard and Arctic Russia).

Stratigraphy and palynology of the Lower Carboniferous Sortebakker Formation, Wandel Sea Basin, eastern North Greenland

Two palynological assemblages of Early Carboniferous age have been recorded from the upper parts of the non-marine, fluvial-dominated Sortebakker Formation in the Wandel Sea Basin. The stratigraphically lower assemblage includes poorly preserved Cingulizonates spp., Densosporites spp., Lycospora spp. and Schulzospora spp. whereas the upper assemblage contains a more diversified microflora including the stratigraphically important Tripartites distinctus, Potoniespores delicatus and Savitrisporites spp. The microflora enables correlation and dating of the succession to the late Viséan Perotrilites tessellatus – Schulzospora campyloptera (TC) and Raistrickia nigra – Triquitrites marginatus (NM) miospore Biozones of western Europe. The depositional facies correspond to those seen in time equivalent deposits from East Greenland, Svalbard, Bjørnøya and the Barents Sea.

Depositional history of the fluvial Lower Carboniferous Sortebakker Formation, Wandel Sea Basin, eastern North Greenland

The Lower Carboniferous non-marine Sortebakker Formation is restricted to the south coast of Holm Land. It is estimated to exceed 1000 m in thickness and is subdivided by a low-angle disconformity into a lower mudstone-dominated unit (c. 335 m) and an upper sand-dominated unit (c. 665 m). The lower mudstone-dominated succession consists of stacked 0.5–6 m thick fining-upward cycles of fine- to medium-grained sandstone and mudstone. Cycles in the upper part of the formation are up to 20 m thick. They are dominated by thick tabular sandstones up to 13 m thick overlain by shaly units that resemble those in the lower mudstone dominated cycles. Six facies associations are identified and together describe a fluviatile–lacustrine depositional system. Five of the facies associations characterise different parts of a meandering riverdominated flood plain whereas the sixth facies association represents more permanent lakes.

Pre-ocean opening compression of the Northwestern Atlantic margin: evidence from eastern North Greenland

The deformation of the Wandel Sea Basin of eastern North Greenland and the West Spitsbergen Fold Belt are the result of Late Cretaceous–Palaeocene Greenland–Barents Sea/Svalbard convergence following the opening of the Labrador Sea–Baffin Bay opening. The Tertiary rocks of the Wandel Sea Basin are undeformed while the Late Palaeozoic–Mesozoic are weakly folded and thrust faulted. Thrust fault movements in North Greenland ceased before Mid-Palaeocene time when the dextral motion separating Greenland and Svalbard began. The shortening was orthogonal to the continental margin and a transpressional origin for the deformation of the Wandel Sea basin is not confirmed.

Airborne gravity survey of Lincoln sea and Wandel Sea, North Greenland

In June 1998 National Survey and Cadastre — Denmark (KMS) carried out an airborne gravity survey over the Polar Sea to the north of Greenland. A Twin Otter from Greenlandair, equipped with autopilot and additional fuel tanks, was employed for the survey. A modified marine LaCoste & Romberg gravimeter and geodetic GPS receivers operating in differential mode made up the basic scientific instrumentation used to monitor the gravity field variations. A laser altimeter and a low cost inertial measurement unit consisting of three gyros and three accelerometers were included to sustain the postprocessing of the GPS data. The presentation will focus on the integration and validation of the system, including comparison with marine and ice gravity measurements. Gravity results from Lincoln Sea and Wandel Sea between latitude 82 N and 85 N, covering the shelf region and the continental slope and rise, will be presented.