Wandel Sea Basin Research Articles

Triassic in the northernmost Atlantic—Linking North Greenland and the southwestern Barents Sea

AbstractThe Wandel Sea Basin in North Greenland was part of the epicontinental Boreal Sea in Triassic time. The basin formed the western margin of the northernmost Atlantic elongated sea connecting southwards with basins along the conjugate Greenland—Norwegian margins. A multidisciplinary dataset including sedimentology, biostratigraphy, organic geochemistry and sedimentary provenance, allow to document its basin evolution. The Wandel Sea Basin was transgressed in the Dienerian with marine deposition prevailing until the Norian. Sediments were mainly sourced from the Greenlandic Caledonian basement and deposited on a 100 km wide shallow marine shelf during the Early Triassic. In Middle Triassic, oil‐prone mudstones formed in oxygen‐depleted deep shelf settings, including eastern Wandel Sea Basin. Detrital zircon U–Pb ages show that by Carnian times, the >1000 km wide, Uralian‐sourced, deltaic shelf had prograded westward across the Barents Sea reaching the eastern north Greenland and de facto nearly closed the northernmost Atlantic Sea.

NE Greenland Composite Tectono-Sedimentary Element, northern Greenland Sea and Fram Strait

Abstract The NE Greenland margin measures more than 300 km from coast to the continent–ocean transition at its widest part and is in an early state of exploration. It is expected to hold significant petroleum reserves due to a high concentration of large structures and prolific source-rock intervals anticipated in the subsurface. The margin is composed of five tectonic units: (1) the Koldewey Platform; (2) the Danmarkshavn Basin; (3) the Danmarkshavn Ridge; (4) the Thetis Basin; and (5) the Wandel Sea Basin. These units form the NE Greenland Rifted Margin Composite Tectono-Sedimentary Element. Rifting commenced at some time during the Devonian or Carboniferous and recurred during latest Jurassic–Cretaceous time. Major tilted fault blocks and other rift-related structures formed during latest Jurassic–Cretaceous rifting. The structures are typically cored by Triassic–Middle Jurassic sand-prone sequences. Oil-prone Upper Jurassic–lowermost Cretaceous marine source rock caps the structures or is located immediately downdip. A large concentration of structures exists in the eastern Danmarkshavn Basin, the western Thetis Basin and along the edges of the Danmarkshavn Ridge. Other major structures exist in the least data-covered parts of the margin furthest north.

Thermo-tectonic development of the Wandel Sea Basin, North Greenland

The Carboniferous–Palaeogene Wandel Sea Basin of eastern North Greenland (north of 80°N, east of 40°W) is an important piece in the puzzle of Arctic geology. It is particularly important for understanding how the Paleocene–Eocene convergence between Greenland, the Canadian Arctic and Svalbard relates to the compressional tectonics in the High Arctic, collectively known as the Eurekan Orogeny. In this study, we present apatite fission-track analysis (AFTA) data and review published vitrinite reflectance data combined with observations from the stratigraphic record to place firmer constraints on the timing of key tectonic events. This research study reveals a long history of episodic burial and exhumation since the collapse of the Palaeozoic fold belts in Greenland. Our results define pre-Cenozoic exhumation episodes in early Permian, Late Triassic, Late Jurassic and mid-Cretaceous times, each involving the removal of kilometre-scale sedimentary covers. Mid-Paleocene exhumation defines the timing of compression along the major fault zones during the first stage of the Eurekan Orogeny, after the onset of sea-floor spreading west of Greenland. Regional exhumation that began at the end of the Eocene led to the removal of most of a kilometre-thick cover that had accumulated during Eocene subsidence and involved a major reverse movement along the Harder Fjord Fault Zone, northern Peary Land. These events took place after the end of sea-floor spreading west of Greenland, and thus, represent post-Eurekan tectonics. Mid–late Miocene exhumation is most likely a consequence of uplift and incision across most of the Wandel Sea Basin study area. The preserved sedimentary sequences of the Wandel Sea Basin represent remnants of thicker strata that likely extended substantially beyond the present-day outline of the basin. We find that the present-day outline of the basin with scattered sedimentary outliers is primarily the result of fault inversion during Eurekan compression followed by deposition and removal of a kilometre-thick overburden.

Middle Jurassic sandstone deposition in the Wandel Sea Basin: evidence from cardioceratid and kosmoceratid ammonites in the Mågensfjeld Formation in Kilen, North Greenland

Age assessments from both palynostratigraphy and macrofossil biostratigraphy of the sandstone-dominated Mågensfjeld Formation, Wandel Sea Basin, North Greenland were hitherto hampered by post-burial thermal degradation of dinoflagellate cysts and a lack of well-preserved macrofossils. The formation was previously assigned to the Upper Cretaceous based on erroneous fossil identifications. Finds of cardioceratid and kosmoceratid ammonites during recent field work now provide the first age control of the unit, demonstrating it to be of late Bajocian – late Bathonian and perhaps Callovian (Middle Jurassic) age. This makes it among the oldest Jurassic units, perhaps even Mesozoic units, recorded in Kilen, North Greenland and eastern North Greenland. Previously, the complex structural and tectonic evolution of the area was poorly understood, and the structural relation of the Mågensfjeld Formation to the surrounding Mesozoic units was a puzzle. The new age assessment simplifies the structural situation in the area significantly. Further, the inference of a large reverse fault previously required to explain the proximity of the Mågensfjeld Formation to neighbouring Jurassic units is now unnecessary. The data show that the Wandel Sea Basin was influenced by the Middle Jurassic transgression and had sufficient accommodation space for marine deposition earlier than previously thought. The unit serves as a key datapoint and analogue for possible Middle Jurassic units in adjacent offshore basins.

Triassic lithostratigraphy of the Wandel Sea Basin, North Greenland

The Wandel Sea Basin in eastern North Greenland forms the northern continuation of the offshore Danmarkshavn Basin and the conjugate margin to the western Barents Shelf south of Spitsbergen. The Triassic succession of eastern North Greenland, up to 700 m thick, spans the Induan (Dienerian) – Norian. The Triassic sediments rest unconformably on Upper Carboniferous and Upper Permian sediments, and are unconformably overlain by Upper Jurassic – Lower Cretaceous deposits. Based on recent fieldwork in the Wandel Sea Basin, five new and revised Triassic formations are described and included in the Trolle Land Group (revised). The Lower Triassic (Induan) Parish Bjerg Formation (revised) consists of marine sandstones, fluvial conglomerates and sandstones, and muddy flood-plain deposits. It is conformably overlain by Lower Triassic (Dienerian – lower Spathian) offshore mudstones with minor sand-dominated intervals of the Ugleungernes Dal Formation (new). The upper Spathian to Ladinian Dunken Formation (revised) is represented mainly by marine sandstones. A marked erosional unconformity characterises the base of the overlying Upper Triassic (Carnian – Norian) Storekløft Formation (new) composed of marginal marine to marine, massive sandstones and conglomerates as well as cross-bedded and biomottled marine sandstones and minor mudstone units. The Isrand Formation (mainly Middle Triassic) consists of laminated mudstones with minor thin sandstone units that were deposited in slope and basin floor settings in the eastern deeper part of the Wandel Sea Basin in Kronprins Christian Land. The Triassic succession of the Wandel Sea Basin represents a well-constrained shallow shelf to deep shelf / basin floor transect and thus forms an excellent outcrop analogue to the time-equivalent intervals in the western Barents Sea basins and the Danmarkshavn Basin offshore North-East Greenland.

Descriptive text to the Geological map of Greenland, 1:100 000, Kilen 81 Ø.1 Syd

The geological map sheet of Kilen in 1:100 000 scale covers the south-eastern part of the Carboniferous–Palaeogene Wandel Sea Basin in eastern North Greenland. The map area is dominated by the Flade Isblink ice cap, which separates several minor isolated landmasses. On the semi-nunatak of Kilen, the map is mainly based on oblique photogrammetry and stratigraphical field work while in Erik S. Henius Land, Nordostrundingen and northern Amdrup Land the map is based on field data collected during previous, 1:500 000 scale regional mapping. Twenty-one Palaeozoic–Mesozoic mappable units were identified on Kilen, while the surrounding areas comprise the Late Cretaceous Nakkehoved Formation to the north-east and the Late Carboniferous Foldedal Formation to the south-west. On Kilen, the description of Jurassic–Cretaceous units follows a recently published lithostratigraphy. The Upper Palaeozoic–lowermost Cretaceous strata comprise seven formations and an informal mélange unit. The overlying Lower–Upper Cretaceous succession comprises the Galadriel Fjeld and Sølverbæk Formations, which are subdivided into six and five units, respectively. In addition, the Quaternary Ymer Formation was mapped on south-east Kilen. The Upper Palaeozoic to Mesozoic strata of Kilen are faulted and folded. Several post-Coniacian NNW–SSE-trending normal faults are identified and found to be passively folded by a later N–S compressional event. A prominent subhorizontal fault, the Central Detachment, separates two thrust sheets, the Kilen Thrust Sheet in the footwall and the Hondal Elv Thrust Sheet in the hanging wall. The style of deformation and the structures found on Kilen are caused by compressional tectonics resulting in post-extensional, presumably Early Eocene, folding and thrusting and basin inversion. The structural history of the surrounding areas and their relation to Kilen await further studies.

Descriptive text to the Geological map of Greenland, 1:100 000, Kilen 81 Ø.1 Syd

The geological map sheet of Kilen in 1:100 000 scale covers the south-eastern part of the Carboniferous– Palaeogene Wandel Sea Basin in eastern North Greenland. The map area is dominated by the Flade Isblink ice cap, which separates several minor isolated landmasses. On the semi-nunatak of Kilen, the map is mainly based on oblique photogrammetry and stratigraphical field work while in Erik S. Henius Land, Nordostrundingen and northern Amdrup Land the map is based on field data collected during previous, 1:500 000 scale regional mapping. Twenty-one Palaeozoic–Mesozoic mappable units were identified on Kilen, while the surrounding areas comprise the Late Cretaceous Nakkehoved Formation to the north-east and the Late Carboniferous Foldedal Formation to the south-west. On Kilen, the description of Jurassic–Cretaceous units follows a recently published lithostratigraphy. The Upper Palaeozoic–lowermost Cretaceous strata comprise seven formations and an informal mélange unit. The overlying Lower–Upper Cretaceous succession comprises the Galadriel Fjeld and Sølverbæk Formations, which are subdivided into six and five units, respectively. In addition, the Quaternary Ymer Formation was mapped on south-east Kilen. The Upper Palaeozoic to Mesozoic strata of Kilen are faulted and folded. Several post-Coniacian NNW–SSE-trending normal faults are identified and found to be passively folded by a later N–S compressional event. A prominent subhorizontal fault, the Central Detachment, separates two thrust sheets, the Kilen Thrust Sheet in the footwall and the Hondal Elv Thrust Sheet in the hanging wall. The style of deformation and the structures found on Kilen are caused by compressional tectonics resulting in post-extensional, presumably Early Eocene, folding and thrusting and basin inversion. The structural history of the surrounding areas and their relation to Kilen await further studies.

Update of the seamless 1:500 000 scale geological map of Greenland based on recent field work in the Wandel Sea Basin, eastern North Greenland

Geological maps are core products of national geological surveys and represent the sum of geological knowledge of any given area. However, dedicated and extensive mapping projects in the Arctic are mostly a thing of the past due to difficulty in financing such costly basic research efforts. Today, an overview of the geology of Greenland is portrayed by a seamless digital 1:500 000 scale geological map (Kokfelt et al. 2013; Pedersen et al. 2013), based on printed maps on this scale produced since 1982 by the Geological Survey of Denmark and Greenland (GEUS; see Holst et al. 2013). The digital map now makes it possible to update smaller areas with new, published or otherwise quality-controlled geological data (e.g. Kolb et al. 2016). This ensures that the map reflects the current state of geological knowledge without undertaking extensive new mapping to update individual map sheets, as has previously been the modus operandi. An online version of the map is available from www.greenmin.dk/map. However, procedures are required to ensure that updates are carried out routinely and that the quality and coherence of the updated map is of the Survey’s standards. Results of recent field work in the Wandel Sea Basin (Fig. 1) and in particular the publication of a new geological map sheet Kilen on a scale of 1:100 000 (Svennevig in press) have implications for the geology shown on the above mentioned 1:500 000 scale seamless geological map of Greenland. The post-Devonian part of this map in eastern North Greenland has been updated according to the results of studies published since the publication of the original printed maps (Bengaard & Henriksen 1986; Jepsen 2000). The changes do not call for an update of the 1:2 500 000 scale geological map of Greenland (Henriksen et al. 2009).

Burial history of a folded Cretaceous succession – A case study from the southern part of Kilen, eastern North Greenland

Kilen is a semi-nunatak in the Flade Isblink icecap in eastern North Greenland with exposures of Mesozoic sedimentary rocks, which are part of the Wandel Sea Basin. Cretaceous marine mudstones and interbedded sandstones of the Galadriel Fjeld and Sølverbæk formations are thrusted and folded in large open folds at Gåseslette in the southeastern part of Kilen. Steeply dipping strata, reflecting parasitic folds and small-scale thrusts, are exposed in low cliffs along a c. 9 km NNW–SSE stretch of the Sølverbæk river. The present study is a case study of the thermal history of these outcrops, called the Sølverbæk section. The burial temperatures are calculated from vitrinite reflectance (Ro) values. Tmax-measurements from Rock-Eval type pyrolysis correlate with the Ro-values. The latter reflects the large-scale folds with higher temperatures in anticlines and lower in synclines. The sedimentary successions are dated on basis of dinoflagellate cysts, inoceramid bivalves and ammonites. The dataset demonstrate a correlation between the Tmax -measurements, maximum burial temperatures, and the preservation of dinoflagellate cysts. The burial temperature at the boundary between the Kangoq Ryg Member and the Sølverbæk Formation varies laterally through a restored section and suggest that the northern part of the section was c. 30° hotter than the southern part prior to folding. Five events are distinguished in the thermal history of the Sølverbæk section: (1) Deposition, (2) rotation of the succession, (3) thermal imprinting, (4) uplift, folding and thrusting, (5) final uplift and erosion up to present day. Following a recent structural model for Kilen events 1–3 are interpreted to be caused by Late Cretaceous rifting where (3) represents maximum burial during rifting. Event 4 is explained by basin inversion of presumed Paleocene–Eocene age.

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.

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.

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.