Norsk Geologisk Forening - Making of a Land

Making of a Land - Chapter 6

Illustraiones chapter 6.

Illustrations can be downloaded in the gallery further down.

		Chapter 06 - pp. 178-179 Lhotse, Nepal (Photo: P. Zycki, CAMC, Polen)
		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.
		Chapter 06 - p. 183a Reconstructions of plate movements when lapetus was closing. (Illustration: T.H. Torsvik)
		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)
		Chapter 06 - p. 184 Ophiolite
		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)
		Chapter 06 - p. 185b Distribution of ophiolite complexes in the Scandinavian Caledonides. The most important ophiolite localities are named.
		Chapter 06 - p. 186 Sulpide ore formation. (Block diagram below from T. Grenne)
		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)
		Chapter 06 - s. 187b Illustration: H. Fossen og R.-B. Pedersen
		Chapter 06 - p. 187c Island-arc rocks (quartz diorite with granite dykes) in the Sunnhordland batholith. (Photo: H. Fossen)
		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)
		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)
		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)
		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)
		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)
		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)
		Chapter 06 - p. 193 The rock problem. (Illustration: H. Fossen, modified after E. Erdtmann, 1896)
		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.
		Chapter 06 - p. 195 Anorthosite quarry at Sirevåg, Rogaland. (Photo: T. Heldal)
		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)
		Chapter 06 - p. 197 Eclogite from Nordfjord. (Photo: H. Fossen)
		Chapter 06 - p. 198 The basement along Sognefjorden has been kneaded like dough during the Caledonian orogeny. (Photo: H. Fossen)
		Chapter 06 - p. 199a Flattening of the basement during the collision: Flattened version of Migmatic gneiss wiht Precambrian structures. (Photo: H. Fossen)
		Chapter 06 - p. 199b Flattening of the basement during the collision: Migmatic gneiss wiht Precambrian structures. (Photo: H. Fossen)
		Chapter 06 - p. 200a The tectonostratigraphy of the Norwegian Caledonides. (Illustration: H. Fossen, based on maps from NGU)
		Chapter 06 - p. 200a Mylonitic augen gneiss. (Photo: H. Fossen)
		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)
		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.
		Chapter 06 - p. 202a Lineation directions and nappe transport. (Modified from A. Kvale)
		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.
		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)
		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)
		Chapter 06 - p. 205a The nappe pile in Finnmark andTroms. (Illustration: H. Fossen and S. Bergh)
		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)
		Chapter 06 - p. 206a A prelude to the orogeny. (Photo: H. Fossen)
		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)
		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)
		Chapter 06 - p. 208a Windows revealing the substrate of the orogenic belt
		Chapter 06 - p. 208b Granite slab in Tysfjord. (Photo: E. Rykkelid)
		Chapter 06 - p. 210 The Balsfjord conglomerate in Troms, flattened and foldedt. (Photo: S. Bergh)
		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)
		Chapter 06 - p. 212 On the summit of Tromsdalstind is eclogite which originated at a depth of 80 km. (Photo: S. Bergh)
		Chapter 06 - p. 213 Tectonostratigraphical map of the allochtons in Nordland and central Norway. (Based on maps from NGU)
		Chapter 06 - p. 214 Fauske marble. (Photo: H. Fossen)
		Chapter 06 - p. 215 Granite rocks in the Rombak window. (Photo: S. Bergh)
		Chapter 06 - p. 216 Caledonian nappes in Nordland. (Photo: H. Fossen)
		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)
		Chapter 06 - p. 217b Chalcopyrite and iron pyrites from Sulitjelma, Nordland. (Photo: H. Fossen)
		Chapter 06 - p. 218 Flagstone - a useful result of the orogeny. (Photo: H. Fossen) Illustration: Locations based on maps from)
		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).
		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)
		Chapter 06 - p. 221b Tectonostratigraphical map of the allochtons in outhern Norway.
		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)
		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)
		Chapter 06 - p. 224a Quartz. (Foto: H. Fossen)
		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)
		Chapter 06 - p. 225 Anorthosite - a useful rock (Photo: I. Bryhni)
		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)
		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)
		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)
		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)
		Chapter 06 - p. 228 Bedrock map of Svalbard
		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.
		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)
		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.
		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)