Fur Formation Research Articles

An early Paleogene trogon (Aves: Trogoniformes) from the Fur Formation, Denmark

ABSTRACT Septentrogon madseni, gen. et sp. nov. is assigned to the family Trogonidae (Aves: Trogoniformes), based on a well-preserved neurocranium from the latest Paleocene–earliest Eocene Fur Formation in north-western Denmark. The taxonomic assignment to Trogonidae is based on an overall similarity and the diagnostic character state of the zygomatic processes, being mediolaterally flattened and rounded in circumference. The specimen is identified as a separate genus and species based on slight proportional differences of the frontals, braincase and zygomatic processes. This new fossil trogon exceeds the hitherto oldest known trogon (and only other known fossil trogon with cranial elements preserved), Primotrogon wintersteini Mayr (1999) by more than 20 Ma. The significant similarity between S. madseni and extant trogons implies that trogons as a taxonomic group morphologically has stayed nearly stationary through time. The palaeoenvironment and palaeoclimate of northern Europe in late Paleocene and early Eocene corresponds well with that in which extant trogons live, and trogons may have followed the movement of the (sub-)tropical climatic belt toward the equator through the Cenozoic rather than adapt to new climatic and environmental conditions.

Silky lacewings (Neuroptera: Psychopsidae) from the Eocene-Paleocene transition of Denmark with a review of the fossil record and comments on phylogeny and zoogeography

AbstractThirty-four fossil insect wings from the Fur Formation of Denmark (Eocene-Paleocene transition) are recognised as neuropteran forewings standing close to extant Psychopsidae (silky lacewings). This affinity is based primarily on their possession of a vena triplica in the forewing. A new genus, Palaeopsychops gen. n. and four new species, P. latifasciatus sp. n. (type species), P. abruptus sp. n., P. angustifasciatus sp. n. and P. maculatus sp. n. are described. Palaeopsychops is identified mainly by the shape of vena triplica and costal space and by the venation of radial space. The new genus appears most closely related to some fossil species of the North American Eocene, while it appears only remotely related to the psychopsid genus Propsychopsis Krüger described from Baltic amber (European Eocene). The different species of Palaeopsychops are separated on relatively minor differences in wing venation and pigmentation. The entire fossil record of psychopsid-like Neuroptera are reviewed and issues of phylogeny and zoogeography are discussed. A total of 5 extant and 21 fossil genera are recognised in the Psychopsidae lineage based on an extended vena triplica definition. The lineage goes back at least to the Upper Triassic. An attempt is made to gather the psychopsid genera into larger natural entities. Extant Psychopsidae are restricted to S. Africa, Australia and SE. Asia. It is suggested that the present relictual distribution is mainly caused by extinction events.

Fossil record of mass moth migration.

The fossil record of moths and butterflies is extremely poor in comparison with other winged-insect groups, with only an estimated 600–700 specimens of fossil Lepidoptera being known1. Here I report the discovery of huge numbers of lepidopteran fossils (about 1,700 specimens) in marine, diatomous sediments of the Fur Formation from the lowermost Tertiary of Denmark (55 million years old). The abundance of the most common species indicates that mass migrations occurred over the Palaeogene North Sea, so the scant fossil record of Lepidoptera reflects poor preservation and not a paucity of lepidopteran species or individuals during the Tertiary.

Lithornithid birds (Aves, Palaeognathae) from the Lower Palaeogene of Denmark

An incomplete sternum and imprints of a right part pelvis and an associated left femur from the uppermost Palaeocene/lowermost Eocene (Fur Formation) of Denmark are assigned to the extinct palaeognath bird order Lithornithiformes Houde 1988, and to the single described family thereof, the Lithornithidae. Morphological features indicate that both individuals were adult birds, smaller than Lithornis cf. nasi, which is represented by an incomplete humerus from the largely contemporaneous, marine Olst Formation in Denmark, and corresponding in size to the smallest known lithornithid, Lithornis hookeri. Lithornithiformes, common in the Palaeocene and Eocene of North America and Europe, were terrestrial birds capable of flight whose remains are often found in aquatic sediments. Both the depositional environment in which the Danish lithornithids were found, and the associated faunal components suggest that the birds were not transported by rivers. Some of the lithornithid species inhabiting NW Europe may have lived and foraged along the shores of the North Sea Basin.

Biostratinomy of insects from the Fur Formation of Denmark (Moler, Upper Paleocene / Lower Eocene)

The different agents influencing the preservation of fossil insects are revised. The mode of preservation of one species of Heteroptera, of Saltatoria, Hymenoptera, Trichoptera and Lepidoptera from the Fur Formation is described and interpreted. All groups have specific modes of preservation depending particularly on the flying behaviour of the living insects, their morphology, floating time, and the activity of algal, fungi or bacterial mats growing on the surface of the bodies. As the example of a bug shows, it is possible to determine, if extensive material is available for comparison, the systematic position of fragments of insects that are difficult to interpret otherwise. Zur Taphonomie fossiler Insekten liegen bislang nur sehr wenige Untersuchungen vor. Es werden daher einleitend verschiedene Einflusse auf die Erhaltung von fossilen Insekten vorgestellt. Auf der Basis umfangreicher Insektenfunde aus der Fur-Formation werden die Erhaltungsmuster eines Vertreters der Heteroptera sowie verschiedener Saltatoria, Hymenoptera, Trichoptera und Lepidoptera beschrieben und ihre Ursachen gedeutet. Fur alle Gruppen zeichnen sich spezifische Erhaltungsmuster ab, die vor allem von der Morphologie, der Driftzeit, dem Flugverhalten der lebenden Tiere und der Bildung von Pilz-, Algenoder Bakterienrasen beeinflust worden sind. Am Beispiel einer Wanze wird gezeigt, das mit Hilfe groser Vergleichsserien auch schwer interpretierbare fragmentierte Individuen systematisch zugeordnet werden konnen.

The calcareous concretions (cementsten) in the Fur Formation (Paleogene, Denmark): isotopic evidence of early diagenetic growth

The Paleogene Fur Formation in northwestem Denmark is a c. 60 m thick clayey diatomite that comprises calcite concretions, the so-called cementsten. The diatomite is interbedded with 179 isochronous and recognizable layers of volcanic ash, which demonstrate that the concretions occur at six stratigraphic levels throughout the Fur Formation. The concretions formed through precipitation of calcite in the pore space within the diatomite or the ash layers. Carbon and oxygen isotope compositions were determined on the concretionary calcite. 613C values around -20%0 to -16%0 indicate that most (bi)carbonate was of bacterial ongin, formed through metabolization of organic matter by sulphate reduction. 6180 values of -1%0 to -3%0 indicate that calcite precipitated at temperatures corresponding to those measured in contemporaneous marine shell materiai. It is speculated that rare blooms of phytoplankton made the six stratigraphic levels the preferred sites of nucleation of the concretions.

Iridium geochemistry of volcanic ash layers from the early Eocene rifting of the northeastern North Atlantic and some other Phanerozoic events

This study shows that some types of explosive volcanism can result in significant Ir anomalies (up to 750 ppt); however, these are readily discerned from impact-related, extraterrestrial Ir anomalies by other chemical and mineralogical criteria. Iridium and major and trace elements were analyzed in 34 of the >180 volcanic ash layers in the Fur Formation of early Eocene age in Denmark. These ashes originate from explosive volcanism during rifting of the Greenland-Eurasia continent and subsequent sea-floor spreading in the young northeastern North Atlantic. In addition, 15 older Phanerozoic ashes, associated with other dramatic global events, have been analyzed for Ir. The Fur Formation ashes are unusually well preserved and have a wide compositional range–for example, rhyolitic, dacitic, tholeiitic and alkaline basaltic, mafic alkaline, and different salic alkaline ashes, and ashes with intermediate or unknown magma origin. The original magma compositions have been determined by immobile-element plots (Nb/Y-Zr/Ti) and other criteria. Iridium shows a bimodal distribution, where all types of salic (alkaline as well as subalkaline) ashes have very low Ir concentrations ( Analyses of 15 of the

Progressive glaciotectonic deformation in Weichselian and Palaeogene deposits at Feggeklit, northern Denmark

Structural analysis of the glaciotectonic deformations at Feggeklit, Mors, Denmark, provide a unique record of succesive deformation phases in a progressive glaciotectonic deformation. The Feggeklit profile displays glaciotectonically folded, thrust-faulted and sheared Palaeogene diatomite with thin volcanic ash layers, the Fur Formation, overlain by a glacigene succession. The combination of stratigraphical and structural analysis shows that the Feggeklit was affected by three glaciodynamic events. The first event is of Saalian age and is represented by the deposition of a till and the formation of a para-authochthonous glacitectonite in the top of the Fur Formation deposits. The second event is only represented by the deposition of a till, probably of Saalian age. The third event is of Late Weichselian age. It includes: 1) deposition of proglacial glaciolacustrine and -fluvial sediments, 2) the formation of a glaciotectonic unit (the Feggeklit deformation complex) and 3) deposition of a till resting on a tectonic uncon-formity formed subglacially. A detailed structural analysis of the glaciotectonic unit provides a subdivision into five succesive deformation phases. The first four phases are related to the proglacial deformation and comprise 1) anastamosing jointing, 2) conjugate faulting, 3) buckle folding and listric thrust faulting, and 4) large scale ramp thrusting. The final phase (5) is related to subglacial shear deformation and loading which produced an allochthonous diatomiteglacitectonite at the sole of the overlying lodgement till. The formation of the structural complex at Feggeklit was caused by two glaciotectonic mechanisms: 1) a proglacial gravity spreading deformation, and 2) a subglacial cataclastic shearing. The balanced cross-section of the fold structures related to the first deformation mechanism indicates that the detachment of the dislocation is situated below the base of the diatomite formation in the plastic clay at a depth of 80-100 m below the surface. Based on the glaciodynamic analysis and considerations on the dating of regional glacigenic setting the velocity of the advancing ice is estimated at 10 m per year. This advance created the gravity spreading deformation reflected in the glaciotectonic structures preserved in the Feggeklit.

Palaeoenvironments in the North Sea Basin around the Paleocene-Eocene boundary: evidence from diatoms and other siliceous microfossils

Abstract Assemblages of siliceous microfossils (diatoms, silicoflagellates, radiolaria, and ebridians) have been examined from calcareous concretions (cementstones) in the Fur Formation, an ash-bearing diatomite which crops out around the Limfjorden region of Jutland, northern Denmark. Although microfossil assemblages (particularly diatoms) change character through the deposit, only one major turnover occurs that is reflected by all of the microfossil groups examined. This biotic event indicates a marked increase in marine influence, and probably climatic warming. It appears to mark the beginning of the early Eocene transgressive phase that affected the whole of the North Sea Basin and eventually re-established this isolated basin’s links with the North Atlantic and Tethys. Other diatom assemblages examined from offshore samples towards the centre of the basin show strong similarities with those from the Fur Formation and confirm that the lower part of this deposit correlates to the Sele Formation, whilst the upper part correlates to the Balder Formation. The lowest occurrence of the widely occurring diatom Fenestrella antiqua is suggested as a practical marker for the base of the Eocene in both offshore and onshore sediments in the North Sea Basin. Restricted circulation processes involving seasonal, monsoon-driven upwelling leading to sporadic basin eutrophication and water-column stratification, are considered to account for the widespread proliferation of siliceous microfossils in the North Sea Basin during the late Paleocene to early Eocene.

CYLINDROSPIRA, A NEW DIATOM GENUS FROM THE PALAEOGENE OF DENMARK WITH PALAEOECOLOGICAL SIGNIFICANCE

A new diatom genus, Cylindrospira is described from the Fur Formation, an Upper Palaeocene to Lowermost Eocene ash-bearing diatomite from North Denmark long renowned for its rich and diverse fossil flora. Two forms have been found, the largest of which, Cylindrospira simsi is designated here as the type species. SEM observations reveal that the structure of this and the smaller forma, homàrmi, have broad similarities with the Cretaceous genus Gladius, the Mid Eocene-Oligocene genus Pyxilla, the Late Eocene—Recent genera Aidacoseira and Melosira, and the Cretaceous-Recent genus Hemiaulus, but have sufficient dissimilarities from these to warrant the erection of a new genus. Associated palynological and sedimentological evidence suggest a brackish, probably lagoonal palaeoenvironment. To date, only fully marine diatoms have been recorded from the Palaeocene.

The Hanklit Gaciotectonic Thrust Fault Complex, Mors, Denmark

The Hanklit cliff section is a classical glaciotectonic locality where an excellent cross-section through a thrust fault complex is exposed. The thrust imbrications were thrust from north to the south during a Late Weichselian glacier advance. Three thrust sheets with thickness of more than 50 m are involved in the thrust fault complex. The deposits exposed in the cliff-section comprise ca. 39 m diatomite with ash layers of Paleocene-Eocene age (the Fur Formation), overlain by up to 27 m of Quaternary glacigenic sediments. Common structural features related to compressional thrust fault helts, are recognizable in the glaciotectonic complex, which shows a lateral shortening of more than 40%. Structures created by soft sedimentary deformation due to high water pressure occur in relation to the thrust fault zones. The structural framework is described with the terminology of thin-skinned tectonics and flats, ramps and hanging-wall anticlines are identified in the cliff-section. A balanced cross section has been constructed. Based on this construction the structural model is verified and the glaciotectonic development is interpreted. A geoelectrical investigation has been made to support the construction of the 3-dimensional framework of the thrust complex. This demonstrates that the impressive Hanklit thrust sheet extends for more than 1 km along the strike and is displaced more than 200 m to the south. Superimposed extentional structures, situated above the sole of the Hanklit Thrust Sheet, are interpreted to be related to Tertiary subsidence tectonics.

Eine Chironomiden-Larve (Insecta: Diptera) aus der Fur-Formation (Paleozän, ? Unter-Eozän; NW-Dänemark)

From the Upper Paleocene/Lowermost Eocene Fur Formation (Moler) of NW Jutland, Denmark, a dipteran larva (fourth instar) is described. On grounds of its morphology and dimensions the specimen can be assigned to the family Chironomidae (non-biting midges). Owing to the mode of development of this family in aquatic habitats, a transport of the larva by wind or active flight to its place of burial can be excluded. Instead, the larva could have been a leftover of a fish meal or transported by currents. The specimen is the first representative of chironomids in the Fur Formation and, additionally, the first wingless stage described from these deposits.

Insekten aus der Fur-Formation von Dänemark (Moler, ob. Paleozän / unt. Eozän?) 8. Zwei neue Vertreter der Chrysopidae (Neuroptera)

Insekten aus der Fur-Formation von Dänemark (Moler, ob. Paleozän / unt. Eozän?) 8. Zwei neue Vertreter der Chrysopidae (Neuroptera)

Geochemistry of basaltic ash beds from the Fur Formation, Island of Fur, Denmark

The major, trace, rare earth and strontium isotopic compositions of five ash layers of Early Eocene age from Knudeklint, Fur (Denmark) have been determined in order to establish the geochemical nature of the magmas and, particularly, to provide geochemical constraints on the source. The sample set includes some layers reported to show systematic local grain size and thickness variations ( +51 and+ 114) as well as layers that apparently lack such variations ( + 1, +35 and +60). Despite these differences, the five layers have remarkably similar compositions, apart from showing a limited degree of fractionation, and are therefore believed to have a common source. The magmas sourcing the eruptions were of continental tholeiite type, comparable to the early Tertiary basalts of the Faeroes-East Greenland province. Var­iations in initial 87Sri86Sr ratio appear to correlate with SiO2, suggesting that small amounts of continental crustal material may have assimilated by the tholeiitic magma prior to eruption.

The Fur Formation, a late Paleocene ash-bearing diatomite from northern Denmark

The Fur Formation (new) is here erected as a formal lithostratigraphical unit. It is a marine diatomite with numerous layers of volcanic ash, and has previously been referred to as "Moler" or the "Mo-clay Forma­tion". The formation is of late Paleocene age and the Paleocene-Eocene boundary is located within a hiatus between the Fur Formation and the overlying Knudshoved Member of the R0snres Clay. The Fur Formation is subdivided into a lower Knudeklint Member and an upper Silstrup Member. The sedimen­tary facies, ichnocoenoses and areal distribution of the formation are described as the basis for an interpretation of the depositional environment.