bluuebunny/crossref_metadata_2025 huggingface dataset:
The crystal structure of naujakasite, a double sheet silicate
Authors: Basso R , Dal Negro A , Della Giusta A , Ungaretti L
Published: June 2021

The crystal structure of naujakasite from Tuperssuatsiait has been determined by X-ray data from four-circle computer controlled Philips PW 1100 diffractometer (Mo Kα radiation). Naujakasite crystallizes in the space group C2/m with cell dimensions a = 15.025(1), b = 7.991(2), c = 10.486(1) Å, β = 113°40'(5'); the structural formula is Na6FeAl4Si8O26, Z = 2. The structure has been solved by Patterson methods and refined by full matrix least-squares method to Rw = 0.027. Naujakasite is a sheet silicate with double layers of tetrahedra perpendicular to the c direction. All the oxygen atoms of the structure are shared between two tetrahedra except one that interrupts the three-dimensional linking. Each single layer is formed by rings of six tetrahedra and the linkage between two single layers gives rise to rings of four and six tetrahedra. Out of the three independent tetrahedral sites present in the structure one is occupied by silicon and the other two by (0.5 Si + 0.5 AI). The Na-O polyhedra (quite irregular) and the Fe-O polyhedron (a tetragonal bipyramid) are all linked together forming a three-dimensional framework in which all the oxygen atoms of the structure are involved.
Organic compounds from the Rhaetic-Liassic coals of Scoresby Sund, East Greenland
Authors: Pedersen K.R , Lam J
Published: June 2021

A large number of aromatic and hydroaromatic hydrocarbons were detected by gas chromatography and mass spectrometry from the bituminous coals. A minor part consists of saturated aliphatic hydrocarbons in which the distribution of normal alkanes in the range C24 to C32 shows a similarity to that of recent plant material with an odd/even distribution rate higher than one. A relatively high amount of pristane is present which is not known in higher plants. A heterocyclic compound, dibenzofuran, was isolated and characterized, and a methyl dibenzofuran seems to be present. Monoterpenoid compounds and minor amounts of acids were detected; myristic and palmitic acids were characterized as methyl esters. The coal is derived from the Kap Stewart Formation which bears a well-known fossil flora dominated by gymnospermous plants and without angiosperms. Some of the extracted organic compounds are present in recent gymnosperms. In recent material dibenzofuran and derivatives are only known in lichens and one angiospermous species.
Early Silurian (Late Llandovery) rugose corals from western North Greenland
Authors: McLean R.A
Published: June 2021

Seventeen species of rugose corals are described from strata of Late Llandovery age in western North Greenland. Grewingkia cuneata sp. nov., Strombodes infractus sp. nov., Amplexoides poulseni sp. nov., Palaeophyllum schuchertense sp. nov. and P. cf. hubeiense Ke & Yü 1974 are recorded from the early Late Llandovery Cape Schuchert Formation. The following species are described from the late Late Llandovery Offley Island Formation: Crassilasma offleyense? (Etheridge, 1878), Pseudophaulactis plectilis sp. nov., Kenophyllum? congestum sp. nov., Craterophyllum vatium sp. nov., C. exporrectum sp. nov., C. prolatum sp. nov., Ptychophyllum tysonense sp. nov., Ptychophyllum sp. A., Ptychophyllum sp. B., Kodonophyllum? pusillum sp. nov., Amplexoides poulseni sp. nov., Cystilasma? rarum sp. nov., and Hedstroemophyllum rhaphis sp. nov.
Stratigraphy, tectonics and palaeogeography of the Jurassic sediments of the areas north of Kong Oscars Fjord, East Greenland
Authors: Surlyk F
Published: June 2021

The lithostratigraphic scheme currently in use for the Jurassic rocks of the Jameson Land area in East Greenland is extended northwards to cover the areas to the north, from Kong Oscars Fjord (72o N) to Store Koldewey (77o N). Most emphasis is laid on the Wollaston Forland area, whereas Traill Ø and Geographical Society Ø are only briefly reviewed. Jurassic sediments are all included in the Jameson Land Group except the latest Jurassic (Middle-Upper Volgian) rocks which are grouped into the Wollaston Forland Group together with Lower Cretaceous rocks of Ryazanian-Valanginian age. Only sediments belonging to the Jameson Land Group are treated here. The group is in the Wollaston Forland area divided into two formations: the Vardekløft Formation below and the Bernbjerg Formation above. The Vardekløft Formation is divided into three members: Pelion Member composed of estuarine sandstones of Bathonian-Late Oxfordian age; Jakobsstigen Member (new) composed of shallow shelf sandstones and mudstones of Early-Late Oxfordian age; and the Muslingebjerg Member (new) composed of barrier-lagoon sandstones and coals of presumed Late Oxfordian age. The overlying Bernbjerg Formation (new) is composed of dark often sandy mudstones of Late Oxfordian-Kimmeridgian (Early Volgian) age. The whole succession is at maximum 1 km thick and reflects deposition in progressively deeper water in a shelf area structurally built of slightly westwards tilted roughly N-S orientated fault blocks. Four regional transgressions controlled by basement faulting can be dated to Bathonian, Early Oxfordian, Late Oxfordian, and Early Kimmeridgian. Each transgression was followed by steady subsidence and prograding sedimentation.
Petrology of the late lavas of the Eriksfjord Formation, Gardar province, South Greenland
Authors: Larsen J.G
Published: June 2021

The uppermost 740-1300 m of the c. 3500 m thick Precambrian Eriksfjord Formation in South Greenland are composed of plagioclase- and olivine-porphyritic basalts and hawaiites of a transitional alkaline type, slightly nepheline-normative trachybasalts, trachyandesites and trachytes and a few flows of phonolite. One ultramafic lava also occurs. Evidence for acid volcanism is restricted to a single small occurrence. The rocks show varying degrees of contact metamorphism and hydrothermal alteration caused by the later Gardar intrusions. Major and trace elements show that fractional crystallization of plagioclase and olivine and minor amounts of clinopyroxene, hypersthene (?) and Fe-Ti oxides possibly governed the differentiation in the basic rocks at elevated pressures. The salic lavas belong to several lineages representing a large range in Na2O/K2O ratios. The covariance of the less mobile trace elements Zr, Nb, Y and Nd suggest that they are not derived from magmas represented by the basalts, but they may have been formed by differentiation of another type of basaltic magma.
Holocene stratigraphy and vegetation history in the Scoresby Sund area, East Greenland
Authors: Funder S
Published: June 2021

The Holocene stratigraphy in Scoresby Sund is based on climatic change as reflected by fluctuations in fjord and valley glaciers, immigration and extinction of marine molluscs, and the vegetation history recorded in pollen diagrams from five lakes. The histories are dated by C-14, and indirectly by emergence curves showing the patterns of isostatic uplift. From c. 10100-10400 to 9400 yr BP the major fjord glaciers showed oscillatory retreat with abundant moraine formation, the period of the Milne Land Moraines. The vegetation in the ice-free areas was a sparse type of fell field vegetation but with thermophilous elements indicating temperatures similar to the present. From 9400 yr BP the fjord glaciers retreated rapidly in the narrow fjords, the few moraines formed are referred to the Rødefjord stages and indicate topographically conditioned stillstands. At 8000 yr BP the low arctic Betula nana immigrated into the area, and in the period until 5000 yr BP dense dwarf shrub heath grew in areas where it is now absent. In the fjords the subarctic Mytilus edulis and Pecten islandica lived, suggesting a climate warmer than the present. From c. 5000 yr BP the dense dwarf shrub heath began to disappear in the coastal areas, and a 'poor' heath dominated by the high arctic Salix Arctica and Cassiope tetragona expanded. These two species, which are now extremely common, apparently did not grow in the area until c. 6000 yr BP. In lakes in the coastal area minerogenic sedimentation at c. 2800 yr BP, reflecting the general climatic deterioration.
Dresbachian trilobites and stratigraphy of the Cass Fjord Formation, western North Greenland
Authors: Palmer A.R , Peel J.S
Published: June 2021

Twenty-five species of trilobites are described, some in open nomenclature. They represent four faunules of Dresbachian age and one faunule of possibie pre-Dresbachian age from the lower 150 m of the Cass Fjord Formation in Daugaard-Jensen Land, western North Greenland. The Cass Fjord Formation ranges in age from Middle Cambrian-Early Ordovician, although until recently it was widely assumed to be entirely of Ordovician age. All the trilobites are typical North American endemic forms. New taxa include: Bonneterrina greenlandica n. sp., Prolonchocephalus spinosus n. gen. n. sp., Kingstonia peltate n.sp., and Terranovella arcuata n. sp. Biogeographic affinities of the older faunules are with faunas of the inner part of the carbonate belt of the Cordilleran region, while the younger faunules have affinities with faunas from the outer(?) part of the carbonate belt in the northern Appalachian region. Evidence of extension of the Dresbachian-Franconian cratonic unconformity to western North Greenland is presented and the problem of repetition of trilobites in the crisis fauna at the base of the Pterocephaliid biomere is discussed.
Silurian graptolites from Washington Land, western North Greenland
Authors: Bjerreskov M
Published: June 2021

Fifty-six graptolite species and subspecies are described from the Silurian sediments of Washington Land and Hall Land, western North Greenland. The graptolite faunas indicate the following ages and zones: Middle Llandovery, the argenteus and convolutus Zones; Upper Llandovery, the turriculatus and spiralis Zones; probably the Llandovery to Wenlock transition; Lower Wenlock, the riccartonensis Zone; Uppermost Wenlock (?) and Lower Ludlow. The bulk of the graptolite species are well known, but some new minor morphological grades are recognised. Four new species and one new subspecies Pseudoclimacograptus (Clinoclimacograptus)? washingtoni, Plectograptus? intermedius, Monograptus kochi, Monograptus teicherti,– and Monograptus bjerringus schucherti – are erected. P. (C.)? washingtoni and P.? intermedius possess morphological characters which are referable to more than one previously described subgenus and genus. The retiolitid fills a gap in the known record of the retiolitids.
Stratigraphy of the Silurian turbidite sequence of North Greenland
Authors: Hurst J.M , Surlyk F
Published: June 2021

A new lithostratigraphic scheme is erected for the Silurian deep-water clastic rocks of North Greenland, from Washington Land in the west to Kronprins Christian Land in the east. All Silurian clastic rocks are included in the Peary Land Group and were deposited in upper to lower slope, submarine fan and basin plain environments. All age determinations are based on graptolites. Ordovician faunas are of North American aspect whilst Silurian faunas are cosmopolitan. Therefore, series and stage definitions in the Ordovician follow American terminology whereas in the Silurian standard international terminology is used. Eight formations and six members are included in the Peary Land Group, which extends from the latest Ordovician (Cincinnatian) to the latest Silurian (Pridoli). Lithostratigraphic units include: Sydgletscher Formation (new) composed of basinal, extremely thick, structureless sandstone beds and black mudstones – Lower Llandovery; Cape Schuchert Formation composed of upper slope mudstones, calcarenites and cherts – Middle Llandovery to lower Upper Llandovery; Lafayette Bugt Formation composed of upper to lower slope mudstones and resedimented limestone conglomerates - Middle Llandovery to Ludlow; Merqujoq Formation (new), a middle to outer fan and basinal sandstone dominated turbidite sequence of 'classical flysch' appearance - uppermost Ordovician (Cincinnatian) to uppermost Llandovery; Citronens Fjord Member (new), a base-of-slope resedimented limestone conglomerate, shale and thin-bedded siltstone and mudstone turbidite sequence – ?Middle Llandovery to Upper Llandovery; Freja Fjord Member (new), an isolated base-of-slope resedimented limestone conglomerate – Upper Llandovery; Wulff Land Formation (new), a lower slope to basin plain black mudstone and thin-bedded fine sandstone and siltstone turbidite sequence – Upper Llandovery to Lower Ludlow; Repulse Havn Member (new), a lower slope to basin plain sequence of thin-bedded mudstone and siltstone turbidites – Lower to Middle Ludlow; Thors Fjord Member (new), a lower slope to basin plain sequence of black mudstones with fine siltstone and sandstone turbidite units – Upper Llandovery to Middle Wenlock; Lauge Koch Land Formation (new), an outer fan and basinal sandstone and siltstone turbidite sequence of 'classical flysch' appearance – Upper Llandovery to Lower Ludlow; Profilfjeldet Member (new), a faulted, folded and cleaved sandstone turbidite and mudstone sequence in Kronprins Christian Land – Upper Llandovery to Middle Wenlock; Nordkronen Formation (new), a sequence of chert pebble conglomerates, pebbly sandstones and sandstones deposited in a base-of-slope and submarine fan environment – ?Middle Wenlock to ?Lower Ludlow; Hendrik ø Member (new) which represents the western distal wedge of the Nordkronen Formation – ?Lower Ludlow; Chester Bjerg Formation (new) composed of basinal laminated mudstones and fine turbiditic sandstones – ?Lower Ludlow to Upper Pridoli..
The stratigraphy of the Upper Jurassic and Lower Cretaceous sediments of Milne Land, central East Greenland
Authors: Birkelund T , Callomon J.H , Fürsich F.T
Published: June 2021

The upper part of the jurassic to Lower Cretaceous succession of Milne Land, described in the present paper, represents an unusually complete, highly fossiliferous sequence of Kimmeridgian, Lower and Middle Volgian and poorly fossiliferous ?Lower Valanginian to Hauterivian deposits. On the basis of some 50 recorded sections the succession is described with respect to lithology and fossil content and placed within a lithostratigraphical frarnework. The Upper Callovian – Middle Volgian Kap Leslie Formation (overlying the Charcot Bugt Formation) is divided into eight members, the upper four of which are described in detail (Gråkløft Member, Krebsedal Member, Pernaryggen Member and Astartedal Member), while the Middle Volgian – Hauterivian Hartz Fjeld Formation above is divided into two members (Hennigryggen Member and Pinnadal Member). A succession of 34 ammonite faunas has been recorded from the Kimmeridgian to Middle Volgian succession of the area. The Kimmeridgian to Lower Volgian faunas match British faunas so closely that the standard zonation of Great Britain can be used. The 17 faunas of the Middle Volgian are closer to successions of northern Russia and Siberia, and the succession has been made the basis of a new regional zonation of nine standard zones for the Boreal Province. One Lower Cretaceous ammonite fauna has been recorded, having ?Early Valanginian age and uncertain affinities. The faunal horizons of Volgian ammonites from Milne Land figured by Spath (1936) in his classical monograph have been determined. Stratigraphically important species found since then have been described elsewhere (Callomon & Birkelund, 1982). The three main areas of outcrops, the Hartz Fjeld area, the Kronen area and the Bays Fjelde area, are correlated in detail on the basis of ammonite occurrences. The depositional environments and tectonic evolution of the Milne Land area are outlined. Some key sections of particular stratigraphical importance are described in an appendix.
Benthic macroinvertebrate associations from the Boreal Upper Jurassic of Milne Land, central East Greenland
Authors: Fürsich F.T
Published: June 2021

From the Upper Oxfordian to the Middle Volgian of Milne Land twenty-two marine benthic macroinvertebrate associations and ten assemblages are described. They occur in silici-dastic, shallow nearshore to offshore shelf sediments. Most of the associations are dominated by bivalves, some by brachiopods, and one by a serpulid polychaete. They are based on 135 samples containing close to 24 000 specimens. For each association, statistical data on faunal composition, trophic composition and life habits are given. The depositional environment of the Milne Land sequence is briefly discussed as are the faunal relationships with other parts of the Boreal Sea (North-East Greenland, Spitsbergen, and northern Siberia).
Reaction between picrite magma and continental crust: early Tertiary silicic basalts and magnesian andesites from Disko, West Greenland
Authors: Pedersen A.K
Published: June 2021

The Kûgánguaq Member is a lava and tuff sequence comprising about 7.S km3 of magnesian silicic basalts (92%), magnesian andesites (7%) and feldspar-phyric silicic basalts ( 18%) through reaction with crustal rocks, presumably Cretaceous sand or siltstones. The reaction led to sulphide fractionation and to magma modification which cannot be explained in terms of crystal fractionation or by simple mixing between magma and contaminants. The transition element (Fe, Ti, Vand Cr) concentrations in rocks, glasses and minerals indicate that the Kûgánguaq Member rocks equilibrated at oxygen fugacities several orders of magnitude below the FMQ buffer, but above the IW-buffer. The partitioning of vanadium between olivine and glass and between chromite and glass show particularly large variations and appears to be the most sensitive recorder of fo2 variations in the range between the FMQ and IW buffers at high igneous temperatures.
Chapter 2: Review of the Lower Palaeozoic basin in North Greenland with special emphasis on petroleum geology
Authors: Christiansen F.G
Published: June 2021

No abstract available.
Proterozoic basins of North Greenland
Authors: Sønderholm M , Jepsen H.F
Published: June 2021

Proterozoic sedimentary and associated igneous rocks along the margin of the Precambrian crystalline shield in North Greenland have been studied by several geological field-teams since 1912 when they were first investigated during the First Thule Expedition. More recently, the Proterozoic strata of North Greenland have been studied in greater detail by the Geological Survey of Greenland (GGU) during the North Greenland Project of 1978-80 and 1983-85. The present paper reviews these studies in an attempt to elucidate the development of the sedimentary basins in North Greenland during the Proterozoic.
The drilling of stratigraphic borehole Umiivik-1, Svartenhuk Halvø, West Greenland
Authors: Bate K.J , Christiansen F.G
Published: June 2021

Svartenhuk Halvø is one of the few areas onshore West Greenland where Upper Cretaceous and Lower Tertiary marine sediments are exposed (Fig. 1). Geological studies in the area have been made intermittently since the late 1930s but have intensified since 1990 as part of the Survey's overall effort to assess the petroleum potential of the Disko - Nuussuaq - Svartenhuk Halvø area and adjacent offshore basins.
Lower Palaeozoic carbonates in eastern North Greenland, and the demise of the 'Sæfaxi Elv nappe'
Authors: Rasmussen J.A , Smith M.P
Published: June 2021

The principal aim of the authors was to document the stratigraphy and structure of Ordovician and Lower Silurian sediments in a c. 5000 km2 area in southern Kronprins Christian Land and westernmost Lambert Land, and estimate the palaeogeographical position of Greenland in relation to the areas surrounding the lapetus Ocean.
Glacier and climate research on Hans Tausen Iskappe, North Greenland – 1995 glacier basin activities and preliminary results
Authors: Thomsen H.H , Reeh N , Olesen O.B , Jonsson P
Published: June 2021

The main goals of the project were to investigate the present and past climate and glacier dynamics of North Greenland by means of ice-core records, ice margin studies, mass balance and climate studies and glacial geological studies on and around Hans Tausen Iskappe.
Hornblendic rocks and their polymetamorphic derivatives in an area NW. of Ivigtut, South Greenland
Authors: Soen O.I
Published: June 2021

Extensive zones of amphibolites and hornblendic rocks occur associated with biotite-plagioclase-quartz schists and garnet-biotite augen-gneisses, in the gneiss areas on NE. Tôrnârssuk and on the peninsula between Kuánit fjord and Tigssalûp ilua (Tigssaluk fjord) in SW. Greenland. Field and microscopic evidences show that these rocks have attained their present constitution mainly in the course of two metamorphic periods, referred to as the main and late-Ketilidian periods of metamorphism. The first period of metamorphism took place under amphibolite facies conditions and is believed to have caused the formation of extensive hornblenditic and amphibolitic layers. Hornblenditic rocks are now only preserved as relics enc10sed in rocks affected by the second period of metamorphism. The second period of metamorphism in the Kuánit area and on NE. Tôrnârssuk occurred under epidote-amphibolite facies conditions. In the Kuánit area a metamorphic differentiation due to differential shearing took place within the hornblenditic layers and resulted in the formation of banded hornblendic rocks, consisting mainly of alternating bands of epidote-hornblende schists, quartz-hornblende schists, magnetite-hornblende schists, and amphibolites, while at places of strongest shearing biotite-plagioclase-quartz schists and tremolite schists were formed. On NE. Tôrnârssuk biotite-plagioclase-quartz schists form more important zones or layers generally adjoining amphibolite horizons. Evidences are presented for the view that these schistose rocks are sheared and pegmatized, originally hornblendic rocks. The adjoining amphiholites are considered as feldspathized hornblendic rocks. The garnet-biotite augen-gneisses and amphibolites in the area south of Tigssalûp ilua are believed to have a similar origin as, respectively, the biotite-plagioclase-quartz schists and amphibolites on NE. Tôrnârssuk. Mineralogical differences are due to the higher grade of the second metamorphism, which reached amphibolite facies conditions in the Tigsalluk area. A third metamorphism during the Sanerutian period was apparently of a low grade or of a low intensity in the areas here under consideration, and it is not thought to have caused significant modifications in the rocks here described.
Fossil plants from the Lower Paleocene of the Agatdalen (Angmârtussut) area, central Nûgssuaq Peninsula, Northwest Greenland
Authors: Koch B.E
Published: June 2021

In the present paper fossil plants are described, which are mainly impressions, from a number of localities in the Agatdalen area of the Central Nûgssuaq peninsula. All the plants are known to be Early Paleocene in age by means of marine evidence and geological investigations. Their state of preservation and mode of fossilization, their taxonomical position, their frequency and phytogeographical relations, their paleoclimatological and local stratigraphical evidence are discussed. This fossil flora which is designated a Macclintockia-Metasequoia-Cercidiphyllum Thanatocoenosis is equivalent to the classic Upper Atanikerdluk A flora of Heer, in composition as well as in age, and represents the Arcto-Tertiary flora. It is also synchronous with the Upper Atanikerdluk B flora (Heer). It gives evidence of a warm (?), temperate climate at the time of deposition. Concerning composition an east asiatic element can still be distinguished here at the very threshold to the Tertiary. It contains relic genera from the Cretaceous.
The ultrabasic rocks at Tovqussaq, West Greenland
Authors: Sørensen H
Published: June 2021

Ultrabasic rocks of bahiaitic type occur as bands in amphibolite at Tovqussaq, It is concluded that the ultrabasics are formed in situ in the amphibolite in zones of stress concentration, Stress of high order in connection with chemically, and mechanically generated heat is regarded to be the cause of the metamorphic differentiation that was responsible for the formation of the ultrabasic rocks, From the results of the examination of the hypersthenes' of the Tovqussaq region it seems reasonable to assume that the hypersthene may be used as a geological thermometer, Ultrabasic rocks are described from other pre-cambrian areas and the peridotites of orogenic zones are discussed, The interpretation of the ultrabasic rocks as being the products of metamorphic. rather than magmatic processes seems to have general validity, Finally, the peridotites are compared with eclogites which were probably formed in a similar way.
The geochemistry of the northern part of the Ilímaussaq intrusion, S.W. Greenland
Authors: Hamilton E.I
Published: June 2021

The Ilímaussaq intrusion (S.W. Greenland) was emplaced into granitic Precambrian basement rocks. The intrusion is of a highly alkaline nature and in terms of rocks types, its major-, minor- and trace elements, may be compared to the Khibina-Lovozero intrusion of the Kola Peninsula, U.S.S.R. The present paper describes the geochemistry of the northern part of the intrusion and the marginal rocks. New total rock analyses are given together with the detailed geochemistry of U, Th, Radioactivity, Nb, Rb, Li and Be. The Ilímaussaq intrusion consists of an early augite syenite chilled against the country rocks. The augite syenite forms a more or less continuous ring around and above the intrusion. The main central mass of the intrusion consists of poorly layered, very coarse-grained, Na-rich "foyaite" containing relatively large amounts of sodalite and eudialyte. Differentiation of the "foyaite magma" gave rise to a volatile rich residual liquid from which lujavrites were formed. Differentiation of the lujavrites in the central area of the intrusion resulted in a lower banded sequence, the kakortokites, and an upper lujavrite liquid. When the confining pressure was exceeded, explosive brecciation occurred and lujavrite was intruded into the surrounding rocks. At a high level in the intrusion a sheet-like body of soda granite was emplaced together with various quart-bearing syenites. The relative time of intrusion of the quartz-bearing syenite is uncertain through lack of field evidence. Emplacement of the early augite syenite may be related to ring faulting followed by cauldron subsidence. The later Na-rich rocks may have replaced the earlier layered augite syenite or have been emplaced into a "magma chamber" developed by cauldron subsidence. The Na-Zr-Cl-rich rocks show evidence of cooling inwards with the development of a central volatile-rich pocket. The Ilímaussaq rocks probably represent a final highly fractionated stage of the more normal augite syenite magma common to the S. W. Greenland alkaline province.
The geology of Tugtutôq and neighbouring islands, South Greenland. Part II. Nordmarkitic syenites and related alkaline rocks
Authors: Upton B.G.J
Published: June 2021

Among the Precambrian (Gardar) intrusions in the Tugtutôq area, syenitic rocks are abundantly represented. Quartz-bearing alkalic rocks were first intruded after the emplacement of a number of large gabbro dykes. Although early Gardar nepheline syenites occur on Tugtutôq, no post-gabbro undersaturated syenites occur within the area under discussion. Quartz syenites and their faster cooled equivalents occur either as ENE directed dykes or as ring-dykes and stocks within a late Gardar central complex. The earliest quartz syenite occurs as the central component in a composite sector of one of the large gabbro dykes. This was succeeded by multiple swarms of dykes with alkalic types ranging from 'rhomb porphyry' microsyenite to comendite. Dyke intrusion was virtually at an end by the time of formation of the central ring-complex. The total petrographic range of the oversaturated alkalic rocks extends from ferroaugite-fayalite syenites with relatively calcic feldspar (ca. Or25Ab66An9) to highly acid riebeckite-bearing rock types. The various intrusions are considered to represent magma batches supplied, at irregular intervals, from a deep-seated syenite complex which was crystallising throughout the latter part of the Gardar period. The inferred sub-surface complex is taken to be closely comparable to the Gardar complexes exposed at Nunarssuit and Kungnât, and to have differentiated by process of crystal fractionation. By analogy with the Kungnât complex the parental magma of the underlying magma chamber(s) is believed to have passed through a larvikitic stage. The perthosite stock which forms the latest major intrusion on Tugtutoq is thought to indicate a slight divergence from the general larvikite-nordmarkite-alkali granite differentiation sequence. The magmas of this main differentiation sequence changed in composition along a "thermal valley" dose to that of the synthetic system Or-Ab-SiO2-H2O.
The petrology of a camptonite sill in South Greenland
Authors: Upton B.G.J
Published: June 2021

A number of small camptonite intrusions were emplaced as dykes and sills at a late stage in the magmatic history of the south Greenland alkaline province in the vicinity of Narssaq and Tugtutôq. Crystal fractionation in one 3 m thick sill lead to the production of a water- and carbon dioxide-rich residuum in the central part of the intrusion. In this central part the concentration and form of ocelli carrying analcite, calcite and zeolites suggests the separation of a vapour phase towards the completion of crystallisation. It is thought that the initial intrusion was of the regional alkali basalt magma modified by an addition of water, carbon dioxide, alkalics and calcium. Kimberlitic or carbonatitic magmas, or alternatively, syenite magma residuals are regarded as possible sources for this volatile-rich increment.
Geomorphological observations on Sermersôq. A contribution to the geomorphology of S. Greenland
Authors: Soen O.I
Published: June 2021

On the island of Sermersôq four erosion surfaces have been recognized, which are of regional importance in S Greenland. Their development is related to three cycles of erosion, interrupted by two glacial stages. The high-level erosion surface at altitudes above 1000 m is the remnant of an old peneplane, which was formed during the oldest erosion cycle and uplifted in late Cretaceous or early Tertiary times. This uplift initiated a second erosion cycle in the course of which a main glacial stage intervened. In this glacial stage the icelevel in the main valleys (the present fjords) acted as the effective base level of erosion and this resulted in the formation of stretches of an intermediate-level erosion surface, which now occur along the main fjords at altitudes between 400 m and 650 m. An important lowering of effective base level of erosion occurred when in the subsequent interglacial stage the sea-level resumed its role as the effective base level of erosion. This event initiated a third erosion cycle in the course of which the low-level erosion surface, between 100 m and 250 m altitude, and the strandflat, a coastal platform below 50 m, were formed. The third erosion cycle was interrupted by a second glacial stage, which on Sermersôq has the localized character of a mountain glaciation; it is during this second glacial stage that the present day fretted upland morphology of central Sermersôq originated. Post-glacial vertical movements causing the emergence of the strandflat induced a rejuvenation of erosion and consequently the incision of this coastal platform and valley floors by recent rivers.
Precambrian organisms and the isotopic composition of organic remains in the Ketilidian of South-West Greenland
Authors: Bondesen E , Pedersen K.R , Jørgensen O
Published: June 2021

The geological setting of organic remnants from well preserved Ketilidian rocks of SW Greenland is presented. The absolute age (2000? m. y.) of the rocks is discussed and compared to that of other regions. Many types of organic remnants have been found in these low-metamorphic rocks. Most of the organic remnants are microscopic globules and fragments with cell-like structures. The type which is best preserved is a complex globular structure on about 1/2mm in diameter. This structure is established as a new monotypic form genus Vallenia erlingi (Raunsgaard Pedersen) n. gen. et sp. Stromatolithes and other macro-structures of possible organic origin are also found. A coal-graphite layer indicates that large-scale accumulation of organic matter has taken place. The organic remnants are so well preserved that it has been possible to extract small amounts of paraffines (n-C11 to n-C31 with maximum about n-C18 to n-C20) and other organic compounds. The carbon-isotope composition from carbonaceous matter and carbonates from a number of samples has been determined. The analytical procedure is described. The result of this investigation shows δ C13-values which indicate that the carbonaceous material is probably of organic origin.
Petrography of a group of alkali-trachytic dyke rocks from the Julianehaab District, South Greenland
Authors: Bondam J
Published: June 2021

The present paper is a result of observations made during the geological mapping of the area around Tunugdliarfik fiord, Julianehaab district, South Greenland, in the summer of 1951.
On the mineralogy of pyrochlore from the IlÍmaussaq alkaline intrusion, South Greenland
Authors: Semenov E.I , Sørensen H , Katajeva Z.T
Published: June 2021

Niobium-bearing minerals such as pyrochlore, igdloite (= lueshite) and epistolite are of widespread occurrence in the Ilímaussaq Intrusion, South Greenland. Furthermore, rock-forming minerals such as eudialyte and rinkite contain one percent or more of Nb2O5. Pyrochlore occurs mainly in rocks of supposed hydrothermal origin and is associated with analcime, natrolite, polylithionite, sphalerite, and a number of other minerals. Four types of pyrochlore are described:1. Brown pyrochlore which is associated with analcime in aggregates several centimetres across. ao = 10.39 Å, n = 2.02 ± 0.01, sp. gr. = 4.12. Nb2O5 = 60.85, Ta2O5 = 0.09, TiO2 = 0.69, SiO2 = 2.00, TR2O3 = 13.03, CaO = 6.30, Na2O = 2.97, U3O8 = 0.35 weight percent, etc.2. Grey pyrochlore forming irregular areas. ao = 10.35 Å, Nb2O5 = 42.06, Ta2O3. = 3.63, TiO2 = 4.09, SiO2 = 14.14, TR2O3 = 6.14, CaO = 9.23, Na2O = 5.34 weight percent, etc. (impure material). 3. White earthy pyrochlore which probably forms pseudomorphs after epistolite.4. Yellow siliceous pyrochlore associated with analcime and neptunite. ao = 10.39 Å, sp. gr. = 3.69, Nb2O5 = 59,91, Ta2O5 = 0.11, TiO2 = 2.66, SiO2 = 10.26, TR2O3 = 2.45, CaO = 8.31, Na2O = 7.46, U2O8 = 0.20 weight percent, etc. It has not been possible to decide whether the silica content is due to mechanical admixture or to isomorphic substitution. As long as this problem is not solved the Ilímaussaq pyrochlore should most properly be termed siliceous pyrochlore.
A study of radioactive veins containing rare-earth minerals in the area surrounding the Ilímaussaq alkaline intrusion in South Greenland
Authors: Hansen J
Published: June 2021

Radioactive veins containing the rare-earth minerals monazite and bastnaesite are found in tension joints in Precambrian sandstone, granite, lavas and dykes on the eastern side of the alkaline Ilímaussaq intrusion in South Greenland. The veins were formed in several phases. First, small cracks were mineralized with hematite, fluorite, quartz and radioactive material. This was followed by emplacement of brown albititic veins in which albite and opaque material predominate, green veins with a high content of ægirine, white albititic veins, carbonate veins and finally quartz veins. All the vein minerals may be coated by a late iron-manganese oxide. Most often the veins are separate, but they may also occur composite. The veins are from a few millimetres to about three metres wide; most commonly they are one to ten centimetres wide. The radioactivity is mostly due to thorium, but a few veins have a uranium content higher than that of thorium. The thorium content ranges from 60 to 4500 ppm, the uranium from 17 to 1500 ppm. The ratio thorium/uranium ranges from 0.1 to 57.2. The radioactivity is predominantly connected with pigmentary material, thorite, thorianite, monazite and bastnäsite. Other minerals identified in the vein are ægirine, acmite, albite, arfvedsonite, apatite, biotite, calcite, chlorite, eudialyte, fluorite, hematite, lithium mica, mesodialyte, microcline, neptunite, pyrite, quartz and sphalerite. The following constants were calculated from X-ray powder diagrams made with a Guinier-Hagg camera.Bastnäsite: a0 = 7.120 ± 7 x 10-3 Å; C0 = 9.77 ± 2 x 10-2 Å; c0/a0 = 1.372; V0 = 428.96 Å3. Monazite: a0 = 6.780 ± 5 x 10-3 Å; b0 = 7.025 ± 4 x 10-3 Å; C
A tetragonal natrolite
Authors: Andersen E.K , Danø M , Petersen O.V , Mouritzen M
Published: June 2021

Tetragonal natrolite has been found as white or, less frequently as, dull pink micro-crystalline aggregates in hydrothermal veins in naujaite, at two separate localities in Ilímaussaq. The aggregates are built up of sheaf-like groups of prismatic crystals, the greatest dimension of which is about 0.01 mm. The single crystals are bounded by a single prism and either a basal pinacoid or a bipyramid. The density is 2.210 ± 0.002. The mineral is uniaxial, optically positive. nε = 1.4093 ± 0.001, nα = 1.4080 ± 0.001. DTA and TOA curves of both ordinary natrolite and tetragonal natrolite are presented; tetragonal natrolite dehydrates at a slightly lower temperature than ordinary natrolite. The mineral is tetragonal, space group probably 142d. The unit cell dimensions are: a0 = 13.0403 ± 0.001 Å, C0 = 6.619 ± 0.001 Å, and Vol. = 2252 Å3. The chemical composition of the mineral falls within the range of composition of natrolites as reported in the literature.
The Mesozoic sediments of Qeqertarssuaq, Umanaq District, West Greenland
Authors: Ødum H , Koch E
Published: June 2021

In 1947, during the work of the Geological Survey of Greenland in the Umanak District of West Greenland, Hilmar Ødum and Eske Koch, under the leadership of A. Rosenkrantz, investigated a small sedimentary area on the west side of Qeqertarssuaq in Karrats Fjord, about 4 kilometers north of the settlement Naujåt (ref. fig. 1). The existence of sediments here was established in 1929 by Lauge Koch (1929, page 259), who, however, was not in a position to undertake a closer examination.
The chemistry and origin of some basement amphibolites between Ivigtut and Frederikshåb, South-West Greenland
Authors: Kalsbeek F , Leake B.E
Published: June 2021

Chemical and modal analyses of 54 amphibolites, 5 biotite gneisses and 5 hornblende-biotite gneisses, into which the amphibolites grade, confirm the field and petrographic evidence that the amphibolites were probably basic tuffs and lavas which, when mixed with varying amounts of quartzo-feldspathic sediment, gave rise to the hornblende-biotite gneisses on metamorphism. Plotted in an alkali-silica diagram 34 samples fall in the field of tholeiite basalt and 20 in the field of alkali basalt while traces of normative nepheline, never exceeding 4 %, occur in only 10 samples. It is shown that the sporadic occurrence of garnet and diopside and the occurrence of up to 15 % quartz are primarily controlled by the original composition of the samples. Garnet is entirely found in amphibolites with low Niggli mg values (0.36-0.45), diopside in samples with relatively high CaO, while modal quartz increases as mg falls. It is therefore possible that the more quartzose and garnetiferous amphibolites formed from late differentiates of the original basaltic magma, but the possibility cannot be excluded that contamination with sedimentary material has played a role, especially in increasing the modal quartz.
The geology of two small layered hornblende peridotite (picrite) plutons in South Greenland
Authors: Berrange J.P
Published: June 2021

Two ultramafic dykes, which pinch and swell both vertically and horizontally and have a form similar to some kimberlite bodies, were intruded 1700 to 1335 m.y. ago during the 2nd episode of Ketilidian plutonism. Contact metamorphism of the adjacent granite was slight -albite-epidote hornfels facies. Petrological, mineralogical and chemical evidence indicates that the parent magma was picritic in composition, that it underwent flowage differentiation as a result of rapid intrusion, and then magmatic differentiation with gravity settling. The internal picritic (chemical classification) layered group crystallised first and includes hornblende peridotites, hornblende-hypersthene peridotites and rare harzburgite. The border group which crystallised later is formed of hypersthene-olivine hornblendites that chemically are picrites, and mica hornblendites that chemically are monzonites with affinities to kentallenite. Hornblende gabbro is a minor late differentiate. Steeply dipping banding cuts the earlier rhythmic layering and is thought to have formed by diffusion of material into cooling cracks developed prior to complete solidification. There are local concentrations of sulphides and platinoids. Three complete silicate analyses and a number of analyses for the platinoids, Au, Cr, Co, Cu, Ni, Ag, Pb and Zn are presented.
Paleocene ostracoda from Nûgssuaq, West Greenland
Authors: Szczechura J
Published: June 2021

This paper is the first description of post-Palaeozoic ostracods from Greenland. The material was collected from the Paleocene (Danian) Agatdal Formation on Nûgssuaq, West Greenland, a formation which has yielded a huge fauna – over 600 species, mostly gastropods and pelecypods. The ostracod assemblage described comprises 96 specimens belonging to 39 species of 24 genera belonging to the suborders Cladocopina, Platycopina and Podocopina. The genera represented have very varied age ranges; some are known from Paleocene to Recent, others range from Jurassic or Cretaceous up to Recent time. One genus, Sclerochilus, has not previously been found in deposits earlier than Miocene, while another, Orthonotacythere, ranges from Jurassic to Paleocene. None of the species could be assigned with certainty to any hitherto described species and therefore the assemblage is considered to be endemic and consequently does not throw new light on the age of the Agatdal Formation. In the case of four species the material is sufficiently well preserved and plentiful to allow the description of the new species Bairdia agatdalensis, Cushmanidea rosenkrantzi, Hazelina nova and Loxoconcha groenlandica.
Kaledonische metamorphose der praekambrischen Charcot Land Serie, Scoresby Sund, Ost-Grönland
Authors: Steck A
Published: June 2021

The metamorphism of the Charcot Land sequence, a succession of sediments, extrusives, tuffs and gabbro and granite intrusions, is described. These rocks, of Precambrian age, rest on a gneissic basement, and are exposed in a tectonic window beneath a Caledonian thrust sheet. One principal metamorphic phase is distinguished, succeeded by a very weak retrograde phase. Locally around the gabbro intrusions traces of contact metamorphism are recorded. The metamorphic assemblages in the tuffs and gabbros, the siliceous dolomites, and the quartzites and mica schists are described and illustrated separately. A progressive northerly increase in metamorphic grade is revealed, the isograds occurring in roughly concentric arcs around a centre in the northern part of the area. Recrystallisation took place under temperature and pressure conditions of Barrovian type, and is probably Caledonian in age.
Further contributions to the knowledge of the Palaeozoic of Slagelse no. 1, Western Sealand
Authors: Poulsen Chr.
Published: June 2021

The material described and discussed in the present paper originates from a deep borehole near Slagelse on western Sealand. The lowermost strata have been referred to the Lower Cambrian (Sorgenfrei & Buch 1964 and C. Poulsen 1969). The present paper deals with the succession of strata between the Lower Cambrian and the Upper Permian evaporite series. The sediments in question are: Alum shale (lowermost part possibly Middle Cambrian and uppermost part possibly basal Ordovician), shales and siltstones with Lower Silurian graptolites (Table 2, p. 11), red, silty claystone (Rotliegendes?), and finally grey dolomite and dark grey, thinly laminated shale with Upper Permian gymnosperm pollen and numerous remains of a vigorous vegetation of hepatics.The description and discussion of the Silurian fossils embrace trace fossils, brachiopods, eurypterids, asteroids, graptolites (e.g. two new species of Dictyonema and a new species of Monograptus), and finally a few vertebrate scales. A study of numerous Silurian specimens of framboidal pyrite resulted in several new observations; the framboids may be explained as primitive pyritized algae.The Upper Permian microflora contains a very predominant new species of Lueckisporites; the macroflora consists exclusively of new species of hepatics referable to Jungermannites and Gessella n.g.The Palaeozoic palaeogeography and geological development of the Slagelse region is discussed in connection with a comparison with sections of some other localities.
Undersøgelse over Nogle danske Sandsorters tekniske Anvendelighed
Authors: Steeoberg N , Harder Poul
Published: June 2021

I Foraaret 1903 henvendte et dansk Ingeniørfirma, d'Hrr. Nyeboe & Nissen sig til Den Polytekniske Læreanstalts Kemiske Laboratorium med Forespørgsel om, hvorvidt det var Laboratoriet bekendt, om der i Danmark fandtes Sandsorter, der var saa lidet jernholdige, at de kunde bruges som Raastof til almindeligt Rudeglas. Laboratoriet henviste Firmaet til at søge Oplysning hos "Danmarks Geologiske Undersøgelse" om Opledningen og Fremskaffelsen af Sandprøver, som Laboratoriet saa lovede at underkaste de fornødne kemiske Analyser og lade foretage de fornødne Smelteprøver med. Efter nærmere Forhandling med Statsgeolog, Dr. Victor Madsen blev det overdraget Assistent ved "Danmarks Geologiske Undersøgelse" cand. polyt. Poul Harder under sine Rejser at udsøge Sandprøver, og Laboratoriet fik oversendt 9 saadanne Prøver.
Eem-Zonerne. Studier over Cyprinaleret og andre Eem-Aflejringer i Danmark, Nord-Tyskland og Holland. Tekstbind
Authors: Madsen Victor , Nordmann V , Hartz N
Published: June 2021

Som det fremgaar af de Undersøgelser, der skal gøres Rede for i den foreliggende Afhandling, findes der bland l de danske, marine Kvartær-Aflejringer Lag, som ere blevne dannede samtidig med de saakaldte Eem-Ariejringer i Holland. Disse Lag have længe været kendte under Navnet Cyprinaleret. Dette blev opdaget af Forchhammer paa en Rejse i Juli 1841. Efter Optegnelserne fra denne at dømme, som findes i hans Manuskriptprotokol II (Mineralogisk Museums Arkiv), synes Formaalet med den at have været at foretage Stentællinger rundt omkring i Landet, en Opgave, som Forchhammer gennem en Aarrække med betydelig Energi arbejdede paa. Forchhammers Rejse er vistnok gaaet over Korsør og Svendborg til Rudkjøbing. Paa Langeland synes han at have gjort Ekskursioner dels over Skrøbelev til Snøde og Frankeklint, dels til Longelse og dels til Ristinge Klint; paa disse Steder har han nemlig gjort Stentællinger, som ere indførte i den omtalte Manuskriptprotokol. Opdagelsen af Cyprinaleret i Ristinge Klint synes at være sket tilfældig; intet tyder paa, at Forchhammer har faaet Underretning om, at der i Ristinge Klint fandtes ejendommelige, skalførende Lerlag, og at han er rejst derhen særlig for at undersøge disse. Han tillagde aabenbart heller ikke straks sin Opdagelse videre Betydning.