Geonytt (ISSN 2703-8580) er et medlemsblad for Norsk Geologisk Forening sine medlemmer.
Medlemmer som ønsker å bidre med artikler, bilder, mitt favoritt geo-sted, morsomme geologiske anekdoter, sammendrag av PhD og MSc oppgaver, informasjon av arrangement som konferanser, møter, ekskursjoner, lokalavdelingsinformasjon, bokomtaler og osv. Eller har dere andre idèer på hva som kan være interessant å lese om, en artikkel som du har lyst å publisere, eller kjenner noen som kanskje kunne tenke seg å bidra med noe? Send inn forslag til Denne e-postadressen er beskyttet mot programmer som samler e-postadresser. Du må aktivere javaskript for å kunne se den. så vil redaksjonskomitèen, bestående av Hans Arne Nakrem (NHM) og Thorbjørn Kaland (HVL), se på innsendte forslag.
Medlemsbladet ble originalt sendt ut til alle medlemmer under navnet Geologinytt i perioden 1972–1988. I perioden 1988–1990 ble det utsendt under navnet Geonytt. Det ble fra 1990 istedet valgt å ha medlemssider i magasinet GEO. Nå har NGF returnert tilbake til Geonytt, som relanseres i digital form. I løpet av 2021 ble det laget fire utgivelser.
Torsdag 7. januar ble NGF sin generalforsamling for første gang holdt digitalt i forbindelse med VK21.
47 medlemmer var med via Teams.
Selv om det ikke ble et fysisk møte, så ble det mulig å diskutere både muntlig og via chat.
Illustrationes chapter 9.
Illustrations can be downloaded in the gallery further down.
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Chapter 09 - pp. 304-305 In Ebbadalen on Svalbard there are folded yellow and red sandstones, alternating with white evaporites and grey limestones from the Carboniferous and Permian. (Photo: A. Nøttvedt) |
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Chapter 09 - p. 308 Map illustrating the major structural elements on the Barents shelf during the Carboniferous and Permian. Elevated highs are shown in green. Subsidence was active in the Nordkapp Basin, which is shown in yellow. Other stippled areas indicate structures that developed later during the Jurassic and Cretaceous. |
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Chapter 09 - p. 309a Reconstruction of Early Carboniferous and Early Permian climate zones. In the Early Carboniferous (upper map), Norway was located in the humid tropical zone, while in the Early Permian (lower map), the climate was hot and arid. (Figures modified from C. Scotese) |
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Chapter 09 - p. 309b Diagram showing the continental drift of Svalbard Since the Carboniferous, Svalbard has drifted progressively northwards over a distance equivalent to about 90 degrees of latitude, or a quarter of the Earth's circumference. (Figure modified from R.J. Steel & D.Worsley) |
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Chapter 09 - p. 310a In the Early Carboniferous, the climate wad humid and characterised by large swamp forests, containing ferns, club mosses and Lepidodendron trees. (Illustration: B. Bocianowski) |
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Chapter 09 - p. 310b In the Late Carboniferous and Permian northern Europe was hot and dry, and reptiles ruled the scorched landmasses. (Illustration: B. Bocianowski) |
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Chapter 09 - p. 311a Stratigraphic dolumns showing Caroniferous and Permian successions on the Barents shelf and in Svalbard. In the Early Carboniferous, we find coal-bearing sandstones and mudstones, while the Late Carboniferous and Permian are dominated by limestines and evaporites. These successions reflect a progressive change from humid to arid climatic regimes. |
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Chapter 09 - p. 311b Diagram showing basin evolution in Central Spitsbergen during the Carboniferous and Permian. The map shows the position of the geological profile and the locations wherethe Carboniferous and Permian rocks crop out.Spitsbergen's evolution is typical of large parts of the Barents shelf. In the Early Carboniferous, sand and mud were deposited in broad basins, while in the Mid-Carboniferous, crustal movements resulted in the formation of narrow and more isolated rift basins. In the Late Carboniferous and Permian, the Barents Sea are developed into a gradualle subsiding, stable platform. BFZ = Billefjorden Fault Zone, LAFZ = Lomfjord–Agardhbukt Fault Zone. (Figure modified from A. Andresen) |
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Chapter 09 - p. 311c Diagram showing basin evolution in Central Spitsbergen during the Carboniferous and Permian. The map shows the position of the geological profile and the locations wherethe Carboniferous and Permian rocks crop out.Spitsbergen's evolution is typical of large parts of the Barents shelf. In the Early Carboniferous, sand and mud were deposited in broad basins, while in the Mid-Carboniferous, crustal movements resulted in the formation of narrow and more isolated rift basins. In the Late Carboniferous and Permian, the Barents Sea are developed into a gradualle subsiding, stable platform. BFZ = Billefjorden Fault Zone, LAFZ = Lomfjord–Agardhbukt Fault Zone. (Figure modified from A. Andresen) |
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Chapter 09 - p. 312a Diagram showing the paleogeography and most important sediment types in the northern areas during the Early Carboniferous. Elongated basins with alluvial plains were developed between Norway and Greenland, while a shallow sea occupied the present Barents shelf area. The locations of Norway, svalbard and Greenland are shown in relation to the Carboniferous plate reconstruction. (Figure modified from H. Brekke) |
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Chapter 09 - p. 312b Paleogeography and depositional environments in Svalbard in the Early Carboniferous. (Figure modified from R.J. Steel and D.Worsley) |
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Chapter 09 - p. 313a From Billefjorden in Svalbard. The photograph shows Lower Carboniferous coal-bearing mudstones and sandstones of the Hørbyebreen Formation. The yellow sandstone beds were deposited in and along the banks of river channels, while the geyish-black mudstone were deposited on flood plains between the channels. (Photo: A. Nøttvedt) |
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Chapter 09 - p. 313b Fossil stem of the club moss Stigmaria, from Billefjorden in Svalbard. (Photo: E.P. Johannessen) |
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Chapter 09 - p. 314a Geological map of Billefjorden on Spitsbergen, showing Carboniferous and Permian successions unconformably overlying Devonian strata. (Figure from NPI, W. Dallmann) |
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Chapter 09 - p. 314b Drill core from the Soldogg Formation in well 7128/4-1 on the Finnmark Platform, showing alluvial plain deposits - pale grey sandstones and dark grey mudstones, separated by a coal seam. (Photo: G.B. Larssen et al.) |
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Chapter 09 - p. 314c Diagram of a seismic profile from the Finnmark Platform. Billefjorden Group sequences exhibit a wedge-shaped geometry and were deposited in half-graben basins during the Early Carboniferous. The Gipsdalen Group also varies somewhat in thickness over large areas. These were deposited after crustal movements in the Barents Sea area had abated. (Figure from G.B. Larssen et al.) |
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Chapter 09 - p. 315 The remains of the mine railway on Bjørnøya. The wreckage is not the result of the passage of time, but of a shelling attack by the British Navy in 1940! (Archive photo) |
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Chapter 09 - p. 316 Paleogeography and the most important sediment types in the northern areas during the Mid-Carboniferous. Shallow marine environments in the Barents Sea area had now expanded to include an elongated gulf extending southwards across Sweden and Finland. The locations of Norway, Svalbard and Greenland are shown in relation to the Carboniferous plate reconstruction. (Figure modified from H. Brekke) |
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Chapter 09 - p. 317a The mountain Pyramiden in Billefjorden on Spitsbergen, with the Russian mining town Pyramiden in the foreground. The pipe-lines on the left lie approximately along the Billefjorden Fault Zone. Dark red Devonian rocks outcrop to the left of the fault. On the right, and closest to the fault, are the greyish-black, coalbearing Lower Carboniferous deposits of the Hørbyebreen Formatin, and these are overlain by alternating red and yellowish-grey Mid-Carboniferous beds of the Ebbadalen Formation. The grey beds at the top of the mountain belong to the Wordiekammen Formation of Late Carboniferous age. (Foto. A. Strøm) |
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Chapter 09 - p. 317b Mid-Carboniferous palaeogeography and depositional environments in Svalbard. (Figure modified from R.J. Steel og D.Worsley) |
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Chapter 09 - p. 317c Detail of Mid-Caroniferous beds from the Odellfjellet Member of the Ebbadalen Formation at Pyramiden. |
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Chapter 09 - p. 318a The mountain Trikolorfjellet at the mout of Austfjorden in Svalbard. The photograph shows interbedded red and yellow sandstones, white evaporites, and greyish-black dolomits from the Trikolorfjel Member, Ebbadalen Formationen. (Photo: A. Strøm) |
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Chapter 09 - p. 318b Schematic section through the Billefjorden Trough on Spitsbergen. Note the marked wedge-shaped geometry of the Ebbadalen Formation deposits. These beds are termed "sync-rift" deposits because they were laid down while subsidence of the trough was ongoing. (Figure from E.P. Johannessen) |
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Chapter 09 - p. 318c Diagram of seismic profile from the Loppa High, extended northwards towards the Bjarmeland Platform. The Gipsdalen Group exhibits a wedge-like geometry and was deposited in half-grabens, as in Svalbard. Note that the faults do not penetrate the Bjarmeland and Tempelfjorden Group units, which were deposited after crustal movements in the Barents shelf area had abated. (Figure from G. B. Larssen et al.) |
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Chapter 09 - p. 319a White gypsum and anhydrite from the Minkinfjellet Formation in Billefjorden on Spitsbergen. The gypsum is formed mainly at the surface by the hydration of anhydrite. (Photo: A.Nøttvedt) |
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Chapter 09 - p. 319b Chicken-wire anhydrite formed on vast sabkhas during the Late Carboniferous. Picture is 15 centimetres wide. (Photo: A.Nøttvedt) |
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Chapter 09 - p. 320 Palaeogeography and the most important sediment types in the northern areas during the Early Permian. (Figure modified from H. Brekke) |
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Chapter 09 - p. 321a From the area between Austfjorden and Billefjorden in Svalbard. Yellowish-grey limestones of the Upper Carboniferous Wordiekammen Formation directly overlie greyish-black basement rocks of the Hecla Hoek Group. Inset: Geologists examine fine-grained limestones within the Wordiekammen Formation. (Photos: A. Nøttvedt) |
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Chapter 09 - p. 321b Thin section from the Ørn Formation in well 7128/6-1. The photograph shows a coarse-grained, bioclastic limestone containing the remains of planktonic foraminifera. (Photo: G. B. Larssen et al.) |
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Chapter 09 - p. 322 Fossils from the Late Carboniferous and Early Permian in Svalbard and Bjørnøya. |
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Chapter 09 - p. 323a Life on the sea floor in the Early Permian. A rich benthic faune inhabited the warm seas, including corals, bryozoans (moss animals), crinoids (sea-lilies), and sponges. From the exhibition ”Life through the ages”, University of Michigan. (Photo: www.palaeos.com/Timescale) |
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Chapter 09 - p. 323b Fossil reef structures from the Wordiekammen Formation near Skansen on Spitsbergen. Inset: The reefs were formed by a single organism, Palaeoaplysina - a plate-like animal resembling the sponges. (Photos: A. Nøttvedt) |
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Chapter 09 - p. 324a The mountain Skansen in Billefjorden on Spitsbergen. The lowermost slope is made up of beds of white and grey gypsum, anhydrite and dolomite of the Gipshuken Formation. The steep uppermost liffs comprise chert beds of the Kapp Starostin Formation. (Photo: A. Nøttvedt) |
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Chapter 09 - p. 324b Seismic relief display from the Loppa High showing polygonal carbonate reef patterns in the Permian sequence. (Figure from D. Hunt) |
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Chapter 09 - p. 324c Seismic line from the Loppa High showing well-defined reef structures within dipping Permian sequences. (Figure from D. Hunt) |
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Chapter 09 - p. 325a Thin section showing Late Permian bryozoans and fusulinids from shallow borehole 7129/10-U-2 on the Finnmark Platform. (Photo: H.A. Nakrem) |
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Chapter 09 - p. 325b Diagram of seismic profile from the Nordkapp Basin showing Late Carboniferous salt penetrating overlying Mesozoic and Cenozoic sequences and reaching the sea floor. During it ascent the salt has carried with it a large block of Permo-Carboniferous limestone. The Mesozoic sequences have been forced upwards and, at the present day, Triassic sandstone beds that have been truncated by the salt diapir form traps for oil and gas. Well 7228/7- 1A is shown penetrating the "Dumbo" prospect. (Figure from K. Sollid) |
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Chapter 09 - p. 325c Von Buch's drawing of Spirifer keilhavii. The permian brachiopod Spirifer keilhavii was described by Professor Keilhau when he visited Bjørnøya in 1827. |
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Chapter 09 - p. 326 Palaeogeography and the most important sediment types in northern areas during the Late Permian. Shallow marine conditions persisted in the Barent Sea area, but mud now became the dominant sediment type in preference to carbonate. The locations of Norway, Svalbard and Greenland are shown in relation to the Permian plate reconstruction. (Figure modified from H. Brekke) |
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Chapter 09 - p. 327a Akseløya in Bellsund on Spitsbergen. Akseløya is composed of vertically-bedded cherts of the Kapp Starostin Formation, and forms a prominent ridge almost blockin the entrance to van Mijenfjorden. The chert beds are very hard, and because of this the glaciers that carved out van Mijenfjorden failed to erode these strata to the same degree as the surrounding rocks. (Photo: A. Nøttvedt) |
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Chapter 09 - p. 327b Drill core from well 7128/6-1 on the Finnmark Platform, showing the transition from greyish-blue limestones of the Isbjørn Formation to greyish-black, silica-bearing mudstones of the Røye Formation. (Photo: G.B. Larsen et al.) |
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Chapter 09 - p. 327c Thin section showing a spiculite unit from the Kapp Starostin Formation. The photograph shows sponge spicules mixed with clay. (Photo: T. Hellem) |
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Chapter 09 - p. 328a Thin section from well 7128/4-1 on Finnmark Platform, showing a spiculite unit from the Røye Formation. The blue colour is an epoxy resin that is used to highlight zones of high porosity within the rock. (Photo: G. B. Larssen et al.) |
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Chapter 09 - p. 328b Late Permian fossils from Spitsbergen, Bjørnøya and the Barents Sea. |
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Chapter 09 - p. 329 Modelled average annual temperature of the Earth's surface during the Late Permian mass extinction. The calculations assume an average annual sea surface temperature of 30-35 degrees at the equator, and 5-10 degrees near the Poles. The model i based on a simulation conductet at the National Center for Climatic Research, Boulder. (Figure from J. Kiehl, www.ucar.edu/news/releases/2005/permian) |
Dette året har vært spesielt for alle, også for oss som jobber med Geologiens Dag. Til tross for uforutsigbare tider så klarte mange å gjennomføre planlagte arrangement. Det skal sies at de største arrangørene meldte avbud, forståelig nok, da mange av dem bruker å ha flere hundre besøkende på sine arrangement. Med utgangspunkt i årets tema som var «klima og geologi gjennom tidene», ble det laget 54 arrangement rundt i hele Norge. Veldig mange av disse arrangementene ble holdt utendørs.
NGF i Trondheim, med leder Trond Svånå Harstad, laget en familievennlig geologisk rebus i Trondheim sentrum. Det var fem forskjellige poster basert på ulike geologiske tidsperioder. På posten for prekambrium fikk man oppleve magnetismen i en bundet jernformasjon. Jakt på kambro-silur fossiler og funn av ortoceras-blekkspruter engasjerte både voksne og barn i post to, før vulkanisme i perm var tema i post tre. De lokale Kaledonske bergartene som vi ser i veggen på erkebispegården var tema for post fire. Etter siste istid var nesten hele Trondheim under vann, noe som ble tema i post fem. Interesserte foreldre og barn kom tilbake til start for å heve premien sin, og uttrykte samtidig glede og undring over alt man kan se i geologien.
I Stavanger ble det arrangert en geologisk sykkelekskursjon, og i Tromsø ble det arrangert tur til Tromsdalstinden og familieaktiviteter på Tromsøya. På turen opp til "Tinden" ble det stopp ved fem geologiske lokaliteter. På Tromsøya fikk besøkende lære om sedimentkjerner som kan brukes til å forstå fortidens klimaendringer og havstrømmer. De fikk kjenne på kvikkleire og lære om geofarer, se ulike mineraler og prøve gullvasking. Stipendiat ved Universitetet i Tromsø, Sofia Kjellman, ble i tillegg intervjuet av NRK Troms om Geologiens Dag.
NGFs avdeling i Oslo arrangerte to turer. Nicola Møller og Morten Bergan var guider på tur langs Lysakerfjorden. Gråhvite kalksteiner og gråsvarte skifre ligger der i rekkefølge langsmed stranda. Det ble fortalt hvordan de ble til og hvorfor de ligger akkurat der. Det ble en reise nesten 450 millioner år tilbake i tid, med sedimenter avsatt i et hav som ikke lenger er der. Man kan se rester etter den voldsomme påvirkningen fra Den kaledonske fjellkjedefoldingen - da dette havet lukket seg og høye fjell bygget seg opp i vest. Det ble også fortalt om riftingen og vulkanismen i permtiden og dannelsen av et nytt hav.Hans Arne Nakrem inviterte til en geologisk rusletur rundt Malmøya, en av øyene i indre Oslofjord, som har en helt spesiell flott geologi. Kyststrekningen som ble besøkt er fredet som geologisk naturminne, noe som forteller litt om områdets unike status. Fossiler og bergarter ble studert, til stor interesse for deltakerne. Foruten disse arrangementene ble det altså laget mange lærerike arrangement rundt i hele landet. Motgangstider tvinger oss til å tenke nytt, og det kommer ofte noe spennende ut av det. Så også for Geologiens Dag.
Illustrations chapter 7.
Illustrations can be downloaded in the gallery further down.
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Chapter 07 - pp. 232-233 The continent of Laurussia, which was formed when Greenland collided with Scandinavian in Silurian to Early Devonian time. The collision zone is marked by the large Caledonian mountain chain. (Small illustration: R. Blakey) |
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Chapter 07 - p. 235 The mountain Litjehesten in the outer part of Sognefjorden. The boundary between the Devonian conglomerates in the Solund Basin and their substrate follows the edge of the shadow. (Phto: T.B. Andersen) |
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Chapter 07 - p. 236a After the basement was forced deep down into the crust during the Caledonian collision (a), and the collision forces died away, it was exhumed again and drawn back towards the east (b). By degrees, the crust was stretched out because new extensional shear zones formed (c) |
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Chapter 07 - p. 236b Such folds are common in large parts of the Caledonian nappe pile in southern Norway. They formed when the mylonites, which were produced during the inward thrusting of the nappes, were deformed whn the nappe pile slid back in the earliest Devonian. Bergsdalen Nappe, West Norway. (Photo: H. Fossen) |
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Chapter 07 - p. 237a The backward sliding of the nappes created structures that reflect the movement direction. The arrows show the directions in southern Norway. They swing from northwesternly in the central mountains to more westerly around the Devonian basins. Broken line mark Devonian extensional shear zones formed by segmantation of the crust after the backward sliding took place. |
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Chapter 07 - p. 237b This photograph shows an approximately 400 million-year-old microdiamond from the Møre coast. (Photo: IKU) |
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Chapter 07 - p. 238 Examples of structures that serve to determine shearing movements in deformed rocks - tools for determining movement directions. |
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Chapter 07 - p. 239a Brurestakken on Atløy, west of Askwoll, is a distinct expression of the strong folding experienced by the Caledonian strata after the Caledonian collision had ceased and Devonian extension had begun. The light-coloured beds are quartzite, which is compacted, lithified and metamorphosed sand from the pre-Caledonian continental shelf. (Foto: H. Fossen) |
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Chapter 07 - p. 239b Devonian basement mylonites in the foreground demonstrate westward movement in the Nordfjord-Sogn Detachment. Lihesten, sculpted in Devonian conglomerates, towers in the north. A low-angle fault separates the Devonian rocks from their Cambro-Ordovician substrate. (Photo: H. Fossen) |
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Chapter 07 - p. 240 Devonian extensional shear zones as they are mapped today. More will probably show up as mapping of such structures continues. |
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Chapter 07 - p. 241a Warm colours on geomagnetic maps indicate especially magnetic bedrock. The continuation of the Hardangerfjorden Shear Zone south-westwards along the Ling Depression is most distinct. The zone thus affected the Permian to Jurassic development of this part of the North Sea. HSZ - Hardangerfjorden Shear Zone. |
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Chapter 09 - p. 241b The Hardangerfjorden has been excavated along one of the longest shear zones or faults in the mountain chain. Basement rocks crop out high on the south side, whereas on the north side nappe rocks rest in what has been referred to as the fold depression. |
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Chapter 07 - p. 242 Simplified block diagram depicting where the extensional shear zones occur in Trøndelag and Nordland, and how they are connected with basement windows. |
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Chapter 07 - p. 243 Photograph of a brittle fault in Øygarden, west Norway. The fault is probably Devonian, and the shiny surface has a coating of finely crushed, green epidote. (Photo: H. Fossen) |
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Chapter 07 - p. 244 The Devonian deposits in west Norway (yellow), together with Caledonian nappe rocks (violet and brown) have been separated from the basement by the Nordfjord-Sogn Detachment. |
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Chapter 07 - p. 245 Death Valley in California is a basin formed between high mountains and faults. Avalanche fans originating at the faults line the foot of the mountains. This landscape probably resembles the original Devonian landscape in Norway. (Photo: H. Fossen) |
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Chapter 07 - p. 246a The first map of the entire Kvamshesten Basin, published by C.F. Kolderup in 1921. The mai aspects are correct, but the contact between the Devonian and its substrate was looked upon as a major thrust fault. |
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Chapter 07 - p. 246b Devonian conglomerate (breccia) in the Håsteinen Basin. Angular boulders imply short transport, perhaps as scree deposits. (Photo: V.V. Vetti) |
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Chapter 07 - p. 247 Fish and plant life. (Photo fosil: H. Fossen) |
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Chapter 07 - p. 248 A drwaing by Hans Reuschs of the unconformity between folded nappe rocks and Devonian conglomeratesn at Bulandet (Sogn & Fjordane). This unconfomrity is beautifully exposed in many places along the coas of western Norway. |
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Chapter 07 - p. 249 Mountains composed of Devonian sandstones and conglomerates viewed from the west towards Kvamshesten.(Photo: P.T. Osmundsen) |
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Chapter 07 - p. 250a Rhythmic rock (Figure modified from R. Steel) |
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Chapter 07 - p. 250b A naked, barren "Devonian landscape" in the mountains near Ålfoten. (Photo: P.T. Osmundsen) |
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Chapter 07 - p. 251a The rhythmic bedding is distinct on the mountainsides near Haukå, east of Florø. (Photo: I. Bryhni) |
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Chapter 07 - p. 251b Simplified model of how enormous thicknesses of Devonian deposits in the Hornelen Basin are envisaged to have been formed. Owing to the curvature of the fault plane, the beds were gradually rotated as they slid down the fault, and new beds were deposited above them. |
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Chapter 07 - p. 252 Folded beds at Grøndalen, at he southern boundary of the Hornelen Basin. The beds that are most resistant to erosion stand out as stripes in the hillside. The light-coloured patches left of centre are the tips of gravel fans stacked on top of one another and derived from the basin margin to the right of the massif. (Photo: H. Fossen) |
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Chapter 07 - p. 251 Devonian sandstones near the Ålfotbreen glacier. (Photo: I. Bryhni) |
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Chapter 07 - p. 254 The beds forming the transition between the Austfjorden Member (yellow, calcareous sandstone) and the Dicksonfjorden member (red sandstone) in the Wood Bay Formation, here beside the Orsabreen glacier, north of Ekmanfjorden, James I Land. (Phto: W. Dallmann) |
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Chapter 07 - p. 255 Feeder pipe to the Quaternary vulcano in the Wood Bay Formation. The locality is near the Breibogen Fault. (Photo: W. Dallmann) |
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Chapter 07 - p. 256a Geological map of part of Svalbard where Devonian deposits are preserved. |
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Chapter 07 - p. 256b A generalised E-W profile across the above map. |
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Chapter 07 - p. 257a Sedimentary facies associations in the Wood Bay Formation. |
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Chapter 07 - p. 257b Sedimentary facies associations in the Wood Bay Formation. |
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Chapter 07 - p. 257c Sedimentary facies associations in the Wood Bay Formation. |
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Chapter 07 - s. 257d Part of the head of a Devonian armoured fish (Arctolepis sp.). Its eye cavity is visible at the upper right. A reconstruction of the fish is seen above. (Illustration: H. Fossen, Photo: Norsk Polarinstitutt) |
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Chapter 07 - p. 258 Folding av Devonian beds belonging to the Grey Hoek Formation. These westward-facing folds belong to the Gråhuken Fold Zone at Bråvallafjella, Vårfluesjøen. (Photo: W. Dallmann) |
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Chapter 07 - p. 259 Quartz vein along one of the faults in the Billefjorden Fault Zonewest of Austfjorden, Dicksons Land. Baryte is found locally in this vein. (Photo: W. Dallmann) |
Illustraiones chapter 6.
Illustrations can be downloaded in the gallery further down.
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Chapter 06 - pp. 178-179 Lhotse, Nepal (Photo: P. Zycki, CAMC, Polen) |
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Chapter 06 - p. 182 This is how Hans Reusch, one of the pioneers in Norwegian geology, imagined that the Caldeonian mountain chain was formed. The crust was pressed together by folding, but the enormous sheets of rock, or nappes, which we now know were detached, are missing. |
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Chapter 06 - p. 183a Reconstructions of plate movements when lapetus was closing. (Illustration: T.H. Torsvik) |
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Chapter 06 - p. 183b Pillow lava from Leka, Nord-Trøndelag. Pillow structures are formed when basaltic lava erupts into water. Note the fine-grained rim around the pillows and the gas vesicles further in. (Photo: R.-B. Pedersen) |
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Chapter 06 - p. 184 Ophiolite |
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Chapter 06 - p. 185a Periodite on Leka. This is what the very lowest part of the iron-rich oceanic crust looks like after it has been on land for more than 100 million years - thoroughly rusty and weathered. (Photo: R.-B. Pedersen) |
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Chapter 06 - p. 185b Distribution of ophiolite complexes in the Scandinavian Caledonides. The most important ophiolite localities are named. |
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Chapter 06 - p. 186 Sulpide ore formation. (Block diagram below from T. Grenne) |
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Chapter 06 - p. 187a Gold is also found in ophiolite complexes in Noway. The largest find has been made on Bømlo, where 137 kg of pure gold were extracted in 1882-1898. Gold can still be found at the site. (Photo: H. Fossen) |
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Chapter 06 - s. 187b Illustration: H. Fossen og R.-B. Pedersen |
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Chapter 06 - p. 187c Island-arc rocks (quartz diorite with granite dykes) in the Sunnhordland batholith. (Photo: H. Fossen) |
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Chapter 06 - p. 188 The Cambro-Silurian rocks of oceanic derivation (Upper Allochthon) range from acid granites that are resistant to weathering to phyllites an other "rotten" rocks. This gives great contrasts in soil and vegetation, as here at Huglo in Sunnhordland where acidic rhyolite forms naked ridges between lush areas of calcareous phyllite. (Photo: H. Sunde) |
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Chapter 06 - p. 189 Granite is one of the commonest rocks in Norway. It largely consists of white to reddish feldspar, quartz and a little mica. Many of the granites in the orogenic belt were formed in island-arc complexes or batholiths prior to the main collision between Norway and Greenland. Trondhjemite (lowermost) was firmed first and more ordinary granites (uppermost) later. (Photo: H. Fossen) |
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Chapter 06 - p. 190a Possible evolution of the Caledonian orogenic belt from just after the plates began to converge in the Late Cambrian until the ocean closed and the actual mountain chain really began to rise around the transition from Silurian to Devonian. (Illustration H. Fossen) |
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Chapter 06 - p. 190b Possible evolution of the Caledonian orogenic belt from just after the plates began to converge in the Late Cambrian until the ocean closed and the actual mountain chain really began to rise around the transition from Silurian to Devonian. (Illustration H. Fossen) |
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Chapter 06 - p. 191 The granites and associated plutonic rocks in Nordland are remnants of island arcs in the lapetus Ocean. Heilhornet, near the border with Nord-Trøndelag (Photo: H. Fossen) |
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Chapter 06 - p. 192 Silurian quartzite conglomerate uppermost in the sedimentary sequence deposited unconformably on the Gullfjellet ophiolite in the Bergen Arcs. (Photo: H. Fossen) |
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Chapter 06 - p. 193 The rock problem. (Illustration: H. Fossen, modified after E. Erdtmann, 1896) |
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Chapter 06 - p. 194 The simplified stratigraphy on the island of Atløy in Sogn og Fjordane. The Høyvik Group corresponds to the sparagmitic rocks further east, and the Särv rocks in Sweden. It was folded and tilted before the deposition of the Silurian Herland Group which, in turn, was overriden by the Solund-Stavfjord ophiolite when the lapetus Ocean closed late in the Silurian. |
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Chapter 06 - p. 195 Anorthosite quarry at Sirevåg, Rogaland. (Photo: T. Heldal) |
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Chapter 06 - p. 196 The Caledonian nappes were piled up in a wedge-shaped stack of nappes in front of the Laurentian "bulldozer". (Illustration: H. Fossen) |
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Chapter 06 - p. 197 Eclogite from Nordfjord. (Photo: H. Fossen) |
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Chapter 06 - p. 198 The basement along Sognefjorden has been kneaded like dough during the Caledonian orogeny. (Photo: H. Fossen) |
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Chapter 06 - p. 199a Flattening of the basement during the collision: Flattened version of Migmatic gneiss wiht Precambrian structures. (Photo: H. Fossen) |
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Chapter 06 - p. 199b Flattening of the basement during the collision: Migmatic gneiss wiht Precambrian structures. (Photo: H. Fossen) |
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Chapter 06 - p. 200a The tectonostratigraphy of the Norwegian Caledonides. (Illustration: H. Fossen, based on maps from NGU) |
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Chapter 06 - p. 200a Mylonitic augen gneiss. (Photo: H. Fossen) |
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Chapter 06 - p. 201a The Jotun Nappe, sparagmitic deposits and phyllitic rocks now lie piled on top of one another (uppermost). If they are drawn out and placed afther one another, the Jotun Nappe proves to have originally been at least 300 km west of its present position, as the lowermost (split) profile shows. (See next page for location) |
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Chapter 06 - p. 201b The main Caledonian lineation directions (arrows) suggest predominantly east-southeasterly transport of rock onto the continent, with additional movement in the longitudinal direction of the orogenic belt in the westernmost nappes. |
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Chapter 06 - p. 202a Lineation directions and nappe transport. (Modified from A. Kvale) |
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Chapter 06 - p. 202b Schematic illustration of where the various main units in the nappes may have been located prior to the collision. Profile line A-B refers to the recontrstructed profile on the previous page. |
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Chapter 06 - p. 203 Stretched out conglomerate clasts are examples of lineations that may help us to calculate oth the transport direction and the deformation intensity. Rundemanen Formation near Bergen. (Photo: H. Fossen) |
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Chapter 06 - p. 204 The sandstones in the Gaissa Nappe here at Austertana in east Finnmark are distinctly folded. One of the worlds's largest quartzite quarries (operated by Elkem Tana) dominates the landscape to the right. (Photo: S. Bergh) |
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Chapter 06 - p. 205a The nappe pile in Finnmark andTroms. (Illustration: H. Fossen and S. Bergh) |
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Chapter 06 - p. 205b Kalak Nappe rocks. The light-couloured quartzitic rock derives from the pre-collision Norwegian continental margin. The dark lenses (boudins) and bands are metamorphosed dolerite dykes which were partialle dismembered during the caledonian orogeny. Porsanger, Finnmark. (Photo: S. Bergh) |
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Chapter 06 - p. 206a A prelude to the orogeny. (Photo: H. Fossen) |
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Chapter 06 - p. 206b The Alta flagstone is metamorphosed Late Precambrian sediment that was foliated during the Caledonian orogeny. It has been quarried for use both indoors and outdoors for around 100 years. (Photo: T. Heldal) |
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Chapter 06 - p. 207 Zircons from the island of Seiland are not just beautiful and sought after by mineral collectors, they are ideal for age determinations using the uranium-lead method. They are just over 550 million years old, that is, from the very latest Precambrian. (Photo: H. Fossen) |
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Chapter 06 - p. 208a Windows revealing the substrate of the orogenic belt |
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Chapter 06 - p. 208b Granite slab in Tysfjord. (Photo: E. Rykkelid) |
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Chapter 06 - p. 210 The Balsfjord conglomerate in Troms, flattened and foldedt. (Photo: S. Bergh) |
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Chapter 06 - p. 211 The Lyngen alps consist mainly of gabbro from the ancient lapetus Ocean between Norway and Greenland. The layering formed when the gabbro magma crystallised, and is an alternation of layers rich in plagioclase and pyroxene and amphibole, respectively. (Photo: S. Bergh) |
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Chapter 06 - p. 212 On the summit of Tromsdalstind is eclogite which originated at a depth of 80 km. (Photo: S. Bergh) |
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Chapter 06 - p. 213 Tectonostratigraphical map of the allochtons in Nordland and central Norway. (Based on maps from NGU) |
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Chapter 06 - p. 214 Fauske marble. (Photo: H. Fossen) |
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Chapter 06 - p. 215 Granite rocks in the Rombak window. (Photo: S. Bergh) |
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Chapter 06 - p. 216 Caledonian nappes in Nordland. (Photo: H. Fossen) |
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Chapter 06 - p. 217a The largest deposits of metalimestone in Norway are in the central part of the Caledonides. The map shows localitites where quarrying is taking place for building stone or industrial use.(Based on maps from NGU) |
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Chapter 06 - p. 217b Chalcopyrite and iron pyrites from Sulitjelma, Nordland. (Photo: H. Fossen) |
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Chapter 06 - p. 218 Flagstone - a useful result of the orogeny. (Photo: H. Fossen) Illustration: Locations based on maps from) |
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Chapter 06 - p. 220 Thrust fault and folds in Ordovician strata near Fornebu, Oslo, formed when the Caledoian nappes were transported from the northwest. (Photo: B.T. Larsen). |
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Chapter 06 - p. 221a The phyllites in the sole thrust between the nappe pile and the basement here inn Voss testify to the intense deformation which they underwent. (Foto: H.Fossen)
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Chapter 06 - p. 221b Tectonostratigraphical map of the allochtons in outhern Norway. |
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Chapter 06 - p. 222 Riplle marks preserved in the arkose overlying the sub-Cambrian peneplain, or basement surface, near Finse. The Caledonian nappes at the Hardangerjøkulen ica cap are seen in the background. (Photo: H. Fossen) |
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Chapter 06 - p. 223 The Jotun Nappe includes anorthosite, which is typically white as here in Nærøydalen, on the boundary between Hordaland and Sogn & Fjordane. (Photo: I. Bryhni) |
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Chapter 06 - p. 224a Quartz. (Foto: H. Fossen) |
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Chapter 06 - p. 224b A bird's-eye view of the Bergen Arcs. The arcs stand out as both topographical and lithological features. (Illustration: H. Fossen) |
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Chapter 06 - p. 225 Anorthosite - a useful rock (Photo: I. Bryhni) |
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Chapter 06 - p. 226a An offshoot of the Olaberget trondhjemite pluton cutting through deformed mafic and felsic volcanites of the Hersjø Formation, Meråker Nappe. From the quarry at Olaberget, 7 km north-northeast of Vingelen, Hedmark county. The trondhjemite is the Early Silurian age, dated isotopically to 43 Ma. (Photo: D.Roberst) |
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Chapter 06 - p. 226b The eastern thrust contact of the Meråker Nappe, Trondheim Nappe Complex, just below Steinfjellet (909 m a.s.l.) about 1 km west of the Swedish border, close to Storlien; looking southwest. A thin slice of Seve Nappe rocks below the cliff, mostly covered by scree, overlies rhyolites and quartzites of the Lower Allochton. (Photo: D. Roberts) |
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Chapter 06 - p. 227a A map of the Løkken mine produced in 1718 looking towards the north. Only the whallow part of the deposit, dominated by copper-rich sulphide stockwork ore, was mined. Subsezuent extraction of the main, massive pyritic ore body continued alont the westward extension to a depth of more than 1,000 m below the surface. (Illustration: Orkla Industrimueseum) |
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Chapter 06 - p. 227b Massiv pyritic ore in contact with jasper bed, Løkken. The deposition of both the ore and jasper was related to hydrothermal ventng at the sea floor. (Photo: T.Grenne) |
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Chapter 06 - p. 228 Bedrock map of Svalbard |
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Chapter 06 - p. 229 The three terranes of Caledonian-deformed rocks in Svalbard. The division is based on differences and similarities in both rock type and structural development. |
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Chapter 06 - p. 229b Marbel, mica schist and amphibolite, recombently folded during the Caledonian orogeny; Sigurdfjellet, northern Spitsbergen. Red Devonian sandstones in the background are separated from the basement by a major fault (the Breibogen Fault). (Photo: NPI, W. Dallmann) |
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Chapter 06 - p. 230 The terrane model for Svalbard proposed by Brian Harland, where enormous lateral movements explain geological differences across substantial lineaments. This map shows the three terranes schematically replaced in their positions at the beginning of the Silurian, as Harland envisaged. |
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Chapter 06 - p. 231 Folded and disrupted layers in a marble-gneiss unit at Liefdefjorden, Svalbard. The severe deformation is Caledonian and the strata belong to the Proterozoic Generalfjella Formation. (Photo: NPI, W.Dallmann) |
Illustraiones chapter 5.
Illustrations can be downloaded in the gallery further down.
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Chapter 05 - p. 148-149 Limestone boulder from Langøya, off Holmestrand, showing a rich variety of Silurian fossils, including corals, brachiopods and bryozoans. (Photo: H.A. Nakrem) |
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Chapter 05 - p.153a Folding of the Cambro-Silurian strata is a result of the collision between Baltica and the American Plate, Laurentia, when the Caledonides were formed in the west. This deformation was quite strong in places, as here in Ordovidian shales at Bygdøy in Oslo. (Photo: D. Worlsey) |
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Chapter 05 - p. 153b Simplified geological map of the Oslo region showing the distribution of Cambro-Silurian sedimentary rocks and Permo-Carboniferous magmatic rocks, as well as the most importen faults. |
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Chapter 05 - p. 154a Life in the Cambrian. Trilobites which crawled on the bottom and swam in the sea are typical representatives of organisms in the Early Cambrian marine environment on Baltica. In other parts of the world, reefs dominated by sponges (in the foreground) have been found, but no such reefs are known in Norway. (Reproduced by permission of the Natural History Muesum, University of Oslo. Illustration: B. Bocianowski) |
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Chapter 05 - p. 154b Trilobites were among the first organisms to evolve a hard shell (exoskeloton) |
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Chapter 05 - p. 155-1 Holmia kjerulfi, a trilobite from the Lower Cambrian (Holmlia shale), Ringsaker (2 cm long). (Photo: H.A. Nakrem) |
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Chapter 05 - p. 155-2 Fossils from Cambrian deposits in the Oslo region |
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Chapter 05 - p. 155a The mikrofossil Torellella, Hadeland (Photo: H.A. Nakrem) |
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Chapter 05 - p. 155b The mikrofossil Lapworthellide, Hadeland. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 155c The mikrofossil Lapworthellide, Hadeland (Photo: H.A. Nakrem) |
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Chapter 05 - p. 155d The trilobite Ptychagnostus gibbus, Slemmestad. (Photo D: M. Høyberget/ D.L. Bruton) |
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Chapter 05 - p. 156a Life in the Ordovician was characterised by cephalopods and graptolites in the water masses and sea lilies, trilobites and corals on the sebaed. (Reproduced by permission of the Natural History Muesum, University of Oslo. Illustration: B. Bocianowski) |
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Chapter 05 - p. 156b Asaphus expansus, the trilobite which W.C. Brøgger illustrated in his work: "Die silurischen Etagen 2 und 3" from 1882. From the Hukf Formation, Tøyen, Oslo. 8 cm long. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 157 Fossils from Ordovician deposits in the Oslo region |
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Chapter 05 - p. 157a The graptolite Rhabdinopora, Tøyen Formation, Tøyen (Oslo) (Photo: H.A. Nakrem) |
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Chapter 05 - p. 157b The graptolite Phyllograptus, Tøyen Formation, Slemmestad (Photo: H.A. Nakrem) |
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Chapter 05 - p. 157c The starfish Cnemidactis osloensis, Elnesformasjonen, Djuptrekkodden (Asker), ca. 4 cm in diameter (Foto C: D.L. Bruton / T. Hansen) |
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Chapter 05 - p. 157d The trilobite Pseudomegalaspis, Elnes Formation, Fiskum (Photo: H.A. Nakrem) |
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Chapter 05 - p. 157e The cephalopod Endoceras (upside down on the bedding plane), Hukformasjonen, Krekling i Buskerud, 4 cm in diameter. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 157f The cephalopod Discoceras, Bønsnes Formation (Upper Ordovician), Stavnestangen (Ringerike), 12 cm in diameter. (Photo: H.A. Nakrem) |
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Chapter. 05 - p. 158 A. Crinoids (1.5 m in diameter) curled on a bedding plane, Vik Formation, Malmøya. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 158a Crinoids (1.5 m in diameter) curled on a bedding plane, Vik Formation, Malmøya. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 158b Crinoid, holdfast ("root"), ca. 20 cm i diameter, Rytteråker Formation, Malmøya. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 158c Favosites, honeycomb coral (arrow) in cross section (field of view is 25 cm wide), Vik Formation, Malmøya. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 158d Bedding plane with several corals, Steinsfjorden Formation, Langøya near Holmestrand. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 158e Monograptus, a graptolite, Skinnerbukt Formation, Malmøya. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 158f Bedding plane with various brachiopods, including Eoplectodonta, Isorthis and Coolina, Solvik Formation, Malmøya. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 159 The graptolite Didymograptus from the Tøyen Formation, Lower Ordovician, Slemmestad, 4 cm long. This type of graptolite is very common in Ordovcian lihologies over large areas, and is therefore a valuable zone fossil. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 160 Thalassinoides, burrows probably excavated by a crustacean or similar articulated animal living in the sea bottom. (Illustration: G. Pemberton) |
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Chapter 05 - p. 161a A landscape from the end of the Silurian, when the first plants began to grow on land. Sea scorpions soon began to creep out of the sea too, and land scorpions, millipedes and mites settled on land, where the plants gave food and protection from the sun. (Reproduced by permission of the Natural History Muesum, University of Oslo. Illustration: B. Bocianowski) |
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Chapter 05 - p. 161b Pharyngolepis, one of the jawless fish found as a fossil in Ringerike. (Illustrasjon: NHM, UiO) |
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Chapter 05 - p. 162 One of the finest fossils found in Norway, the 75 cm long sea scorpion, Mixopterus kiaeri, found in red sandstone near Kroksund, Ringerike. When Johan A. Kiær described the discovery in 1924 he wrote: "I'll never forget the moment when we found this new scorpion. My assistants had just turned over a large flat stone when we saw the big creature with its outstretched flippers. It looked so natural we almost expected it to get up from the spot where it had been resting for so many millions of years and creep down to the lake below us.". (Foto: P. Aas, NHM, UiO) |
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Chapter 05 - p. 163 Nodules and trace fossils |
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Chapter 05 - p. 163a Calcareous nodules in dark shale from Hovedøya (Skogerholmen Formation, Ordovicioan). (Photo: H.A.Nakrem) |
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Chapter 05 - p. 163b Cross section of nodules and some fossil fragments, a coral and some crinoid stems in and around the nodules (Rytteråker Formation, Silurian, Malmøya), field of view is 30 cm (Photo: H.A.Nakrem) |
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Chapter 05 - p. 163c Nodules in the form of burrows (Rytteråker Formation, Silurian, Malmøya), the burrows are 10–20 mm in diameter. (Photo: H.A.Nakrem) |
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Chapter 05 - p. 163d Cambrian cannonballs (Alum Shale Formation, Slemmestad). (Photo: H.A.Nakrem) |
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Chapter 05 - p. 163e Bedding plane with fine grazing burrows (Chondrites type) (Solvik Formation, Sillurian, Malmøya), the burrows are about 2 mm in diameter. (Photo: H.A.Nakrem) |
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Chapter 05 - p. 163f Weathered bedding plane which shows a maze of coarse burrows (Vik Formation, Silurian, Malmøya), the burrows are 10–20 mm in diameter. (Photo: H.A.Nakrem) |
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Chapter 05 - p. 164 Generalised stratigraphical table showing the division of the Cambro-Silurian succession and characteristic aspects in the central part of the Oslo region (Oslo-Asker) |
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Chapter 05 - p. 165 Black Middle Cambrian shales lie directly on Precambrian basement and are overlain by a horizontal intrusive sill og light maenaite at Slemmstad, in the centre of the Oslo region. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 166 Large Lower Ordovician carbonate "cannonballs" are exposed in the Alum Shale at Nærsnes, Near Slemmestad. (Photo: B.T. Larsen) |
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Chapter 05 - p. 167a Schematic block diagrams showing the Cambrian and Ordovician depositional development of the Oslo region |
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Chapter 05 - p. 167b Schematic block diagrams showing the Cambrian and Ordovician depositional development of the Oslo region |
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Chapter 05 - p. 167c Schematic block diagrams showing the Cambrian and Ordovician depositional development of the Oslo region |
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Chapter 05 - p. 167d Schematic block diagrams showing the Cambrian and Ordovician depositional development of the Oslo region |
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Chapter 06 - p. 169 A greenish, readily weatering layer of bentonite (fossil volcanic ash), approximately 1 m thick, is found withhin dark Odovician shales of the Arnestad Formation in Asker. (Photo: H.A. Nakrem) |
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Chapter 05 - P. 170 Tidal channel filled with boulders of calcareous sandstone uppermost in the Ordovician (the Langøyene Formation) on Kalvøya. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 171a The Ordovician Tromsdal limestone is quarried in Verdal, Nord- Trøndelag. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 171b The cliff of Tsjebysjovfjellet on the south side of Hornsund, Svalbard. The rocks are almost unmetamorphosed carbonates in Nørdstetind Formation, which is part of the Ordovician Sørkapp Land Group. The recumbent isoclinal fold is of Caledonian age and is probably a folded nappe. (Photo:W. Dallmann) |
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Chapter 05 - p. 171c Distribution of Cambro-Silurian rocks (black) in Norway and adjacent part of western Sweden. (From: H. Fossen)
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Chapter 05 - p. 172 Cambro-Silurian fossils from localities outside the Oslo region |
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Chapter 05 - p. 172a Rhabdinopora, an Ordovician graptolite, Digermul Peninsula, Finnmark (field of view is 6 mm wide). (Photo: H.A. Nakrem) |
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Chapter 05 - p. 172b Syringophyllum, a coral in metamorphosed and deformed Silurian limestone (marble), Bergen (the coral is 3 mm in diameter). (Photo: H.A. Nakrem) |
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Chapter 05 - p. 172c Peltocare compactum, an Ordovician trilobite, Digermul Peninsula, Finnmark (ca. 12 mm long). (Photo: H.A. Nakrem) |
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Chapter 05 - p. 172d Drill core showing brachiopods and corals, from the Farsund Basin (Lower Silurian), Skagerrak (the core is 5 cm in diameter). (Photo: H.A. Nakrem) |
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Chapter 05 - p. 172e Deformed trilobite Calymene, Silurian, Bergen (Reusch's original specimen), (the trilobite is 1 cm across). (Photo: H.A. Nakrem) |
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Chapter 05 - p. 172f Solidary corals ("Cyathophyllum") in metamorphosed and deformed Silurian limestone (marble), Bergen (The corals are 1 cm in diameter). (Photo: H.A. Nakrem) |
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Chapter 05 - p. 172g Colonial corals ("Syringophyllum") in metamorphosed and deformed Silurian limestone (marble), Bergen (The coral is 3 mm in diameter). (Photo: H.A. Nakrem) |
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Chapter 05 - p. 172h Gonioceras, a cephalopod from the Ordovician on Bjørnøya (25 cm long) (Photo: H.A. Nakrem) |
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Chapter 05 - p. 173a Schematic block diagrams showing the Silurian depositional development of the Oslo region. |
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Chapter 05 - p. 173b Schematic block diagrams showing the Silurian depositional development of the Oslo region. |
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Chapter 05 - p. 173c Schematic block diagrams showing the Silurian depositional development of the Oslo region. |
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Chapter 05 - p. 173d Schematic block diagrams showing the Silurian depositional development of the Oslo region. |
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Chapter 05 - p. 174 A. Relatively flat reef structure (1 m thick) in the upper part of the Rytteråker Formation at Limovnstangen, Ringerike. The yellow broken line denote the reef surface, the red one its base and the blue one the reef flank. |
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Chapter 05 - p. 174b Reef-building coral: Halysites (chain coral) (Photo: H.A. Nakrem) |
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Chapter 05 - p. 174c Reef-building coral: Favosites (honeycomb coral) (Photo: H.A. Nakrem) |
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Chapter 05 - p. 175 Sediments and reconstructed depositional environment from the end of the Silurian period |
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Chapter 05 - p. 175a The shift from green, coastal sandstone to red, continental sandstone in Ringerike, with wave ripples in the red beds, probably formed in a lake or lagoon with fresh or brackish water. Kroksund, Ringerike. (Photo: H.A. Nakrem) |
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Chapter 05 - p. 175b A river channel has cut down into more fine-grained fluvial sediment. Ringerike Sandstone, Sundvollen, Ringerike. (Photo: D. Worsley) |
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Chapter 05 - p. 175c Model of the sea scorpion, Mixopterus kiaeri, in its natural habitat in these lakes. (Natural History Museum, University of Oslo. Foto: H.A. Nakrem) |
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Chapter. 05 - p. 175d Model of the primitive fish, Aceraspis, which lived with the sea scorpions. (Natural History Museum, University of Oslo. Photo: H.A. Nakrem) |
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Chapter. 05 - p. 176 Paleogeographical map of Baltica at the transition from Early to Late Silurian: the Caledonides were rising in the north and west, while the southern margin of Baltica formed a deep foreland basin towards the Palaeotethys Ocean. (Illustration: T. Torsvik)
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Chapter 05 - p. 177a Life in a fossil reef reconstructed and modellen on the basis of the reef at Limovnstangen, Ringerike. The reef was primarily built up of corals (B,D,I,K,L) and calcareous sponges (stromatoporoids) (A), but brachiopods (F), bryozoans (G), gastropods (C), algae and sea lillies (H) were all important components in this environment. Trilobites crawled among the sedentary organisms, while cephalopods (J) swam in the sea surronding the reef. (NHM, UiO. foto H.A. Nakrem) |
Illustrations chapter 4.
Illustrations can be downloaded in the gallery further down.
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Chapter 04 - p. 120-121 Giemašfjellet, on the east side of Tanafjorden, consists of folded sandstones of Neoproterozoic age. The pure quartz rocks are quarried at Austertana to use the quartz for industrial purposes. The successions from the last part of the Precambrian are very well exposed and thoroughly studied in the Tanafjord–Varangerfjorden region. (Photo: A. Siedlecka) |
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Chapter 04 - p. 122 Simplified map of the Baltica continent as it may have looked when it separated from the supercontinent, Rodinia. The north-eastern and north-western margins, the Timanian and Baltoscandian margins, respectively, delimited the "Norwegian" part of the continent. |
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Chapter 04 - p. 123 Map of the north-western part of Baltica showing the present distribution of Neoproterozoic sedimentary rocks (yellow) in Norway and along the Caledonian thrust front. The Neoproterozoic Gardnos Crater and the Fen volcano are situated at Gardnos and Fen, respectively. Other Caledonian rocks are indicated with pale grey colour. |
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Chapter 04 - p. 124 Geological map of Finnmark showing the most important divisions of the bedrock. Compiled from various sources. |
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Chapter 04 - p. 125 The Neoproterozoic to Cambrian successions in the Tanafjorden – Varangerfjorden and Barents Sea regions. (Adapted from several works by A. Siedlecka) |
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Chapter 04 - p. 126a Podolina minuta, a star-shaped acritarch, a microfossil, just a few micromillimeter in size, from the lower part of the Vadsø Group beside Varangerfjorden, on av the oldest fossils in Norway, found, prepared and photographed by Gonzalo Vidal. |
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Chapter 04 - p. 126b Shallow-water marine sandstone beds in the Dakkovarre Formation of the Tanafjorden group at Skallnes on the south coast of the Varanger Peninsula. (Photo: A. Siedlecka) |
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Chapter 04 - p. 126c Dark-red mudstone and light-red sandstone in the Fugleberget Formation on the south side of the island of Vadsø. The beds were deposited as sandbanks in rivers. One sand bed was folded by the force of strongly flowing water during a flood. (Photo: A. Siedlecka) |
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Chapter 04 - p. 127 Examples of columnar and branching stromatolites in the Porsanger dolomite on the west side of Porsangen, near Trollsundet. (Photo: A. Siedlecka) |
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Chapter 04 - p. 128 The Bigganjarga tillite at Oibacšanjarga in Varangerbotn, is fossilised moraine from the approximately 600 million-year-old Varangerian Ice Age. This world-famous deposit is protected. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 129a Thick, grey, turbiditic sandstones of the Kongsfjord Formation beside the Barents Sea in Kongsøyfjorden, Varanger Peninsula. The beds were deposited as huge submarine sand fans more than 700 million years ago. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 129b Multicoloured beds of shales, sandstones and dolomites in the upper part of the Båtsfjord Formation in the Barents Sea Group in inner Persjorden, Varanger Peninsula. (Photo: A. Siedlecka) |
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Chapter 04 - p. 130 Ediacaran fossils from the Stáhpogieddi Formation at the Precambrian-Cambrian boundary on the south coast of the Digermulen Peninsula. The imprints are of round, jellyfish-like organisms, a few centimetres in diameter. (Photo: A. Siedlecka) |
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Chapter 04 - p. 131 The geological development of the Tanafjorden-Farangerfjorden region southwest of the Trollfjorden-Komagelva Fault Zone (TKFZ) and the Barents Sea region northeast of the fault zone. a) Deep-water and, later, shallow -water marine sediments were deposited in a basin northwest of the Varanger Peninsula. b) and c) Sediments were deposited on fluvial plains and in shallow sea in the Tanafjord-Varangerfjord region. d) The successions of the Barents Sea Group and the Løkvikfjellet Group slide from northest to southeast along the TKFZ and form the Barents Sea region on the northeast side of the Varanger Peninsula. |
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Chapter 04 - p.132 Chalk-white Porsanger dolomite in 30 °C and a heat haze near Børselv in Porsangen casts our minds back to the hot areas in southern latitudes where this carbonate deposit was formed some 650 million years ago. The snow on the mountains in the background reminds us of the great climatic changes in the i Neoproterozoic. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 133 Sparagmite, feldspar-rich sandstone (arkose), sometimes containing large, angular clasts, was named by Jens Esmark in 1829. (Photo: I. Bryhni) |
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Chapter 04 - p. 134 Igneous rocks in the Seiland Province, Reinfjorden, on the Øksfjord Peninsula. Gneiss on the lower slope of the mountainside is intruded by layered igneous rocks which occupy the upper part of the cliff. Black ultramafic rocks occur in two series separated by an older, light-grey gabbro. The nearly 600 m high mountainside provides a section thourgh a huge magma chamber. (Photo: B. Robins) |
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Chapter 04 - p. 135 Light-coloured metasandstone in the Kalak Nappe Complex cut by dolerite dykes metamorphosed to amphibolite. The rocks probably derive from a basin on the outer side of Baltica and were moved several hundred kilometers during the Caledonian orogeny. Road cut south of Hammerfest on Kvaløya. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 136 The Sparagmite Region in south Norway. |
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Chapter 04 - p. 137 The Rondane Mountains consist of hard, Late Precambrian metasanstones that are approximately 650-750 million years old. During the Caledonian orogeny, these sandstones were thrust several hundred kilometres eastwards from basins along the Baltoscandian margin of Baltica. (Photo: C. Harbitz) |
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Chapter 04 - p. 138 The succession in the Hedmark Basin, the Hedmark Group; the western part to the left and the eastern to the right. |
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Chapter 04 - p. 139a Rendalssølen (1754 m) is a landmark in the sparagmite region of eastern Norway. The mountain is composed of the Rendalen Formation, sandstones deposited by rivers in the eastern part of the Hedmark Basin 700–750 million years ago. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 139b Cross-bedded sandstone from an infilled river channel in the Rendalen Formation on the summit of Rendalssølen. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 139c Limestone breccia in the Biri Formation in a road cut on E6 at Kremmerodden, Biri. Up to 50 cm long fragments of the limestone were broken up by tidal currents or powerful waves. (Photo: J.P. Nystuen) |
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Chapter 04 - P. 140a The Brøttum Formation in Maihaugvegen, Lillehammer. Beds of turbiditic sandstones and shales were deposited on the floor of hte Hedmark Basin and raised into a vertical position during the orogenic movements at the end of the Silurian. The shaley beds contain acritarchs, the oldest fossils found in southern Norway. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 140b Beds of conglomerate and sandstone in the Biskopåsen Formation in a road cut near Havik on the east side of Lake Mjøsa. The beds are vertical due to thrusting during the Silurian-Devonian Caledonian orogeny.. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 141 Evolution of the Hedmark Basin through six phases from its initial formation by rifting until Baltica was covered by the sea at the beginning of the Cambrian 542 million years ago. |
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Chapter 04 - p. 141a- b a) 750 mill. yrs |
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Chapter 04 - p. 141c-d c) 680-650 mill. yrs |
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Chapter 04 - p. 141e-f e) 570-550 mill.yrs - Ediacaran time |
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Chapter 04 - p. 142a Papillomembrana compta, the first Precambrian fossil found in Norway. The fossil, of unknown affinity and just over 1 mm long, was found by Nils Spjeldnæs i 1959 in a phosphorite clast in the Biskopåsen Formation near Havik, beside Mjøsa. (Photo: N. Spjelndæs) |
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Chapter 04 - p. 142b A rock core (4 cm in diameter) from Østre Æra, between Rena and Ossjøen in Østerdalen. Basalt lava (dark) flowed over unconsolidated sand (light coloured), some of which was rolled into the base of the lava. The lava extrusions took place during an active rifting phase in the Hedmark Basin. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 143a Moelv tillite from the approximately 600 million-year old Varangerian Ice Age exposed as ice-polished rock from the last Ice Age, about 10 000 years ago. The tillite has large and small clasts of basement rocks and limestone. Bruvollhagan, Moelv. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 143b The Ringsake quartzite from the very base of the Cambrian, the youngest part of the Hedmark Group, Steinsodden on the east side of Mjøsa in Ringsaker. Looking northwards towards Mjøsa Bridge. Lundehøgda and Biskopåsen in the background are also in the type are for the Hedmark Group. (Photo: J.P. Nystuen) |
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Chapter 04 - p. 143c The Ringsaker quartzite, with vertical burrows excavated by a lugworm-like mollusc. Langodden, on the east bank of Lake Mjøsa. (Foto: J.P. Nystuen) |
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Chapter 04 - p. 144 Old source rock for oil: black shale in the Brøttum Formation in Maihaugvegen in Lillehammer. Black shale with a high content of organic carbon (black) is overlain by a thin layer of silt with light-coloured quartz grains. The silt has sunk into the clay, forming the boot-shaped structure. (Foto: M.K.M. Skaten) |
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Chapter 04 - p. 145a The Gardnos Crater. |
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Chapter 04 - p. 145b The Gardnos Crater. Cross section through the Gardnos Crater. |
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Chapter 04 - p. 145c The Gardnos Crater. Core from Branden. |
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Chapter 04 - p 146 Geological map of the Fen area. The rocks were formed by many different magmatic processes far below the summit of the Fen volcano. (Modified after E. Sæther) |
