Geologie na konci 20. století přešla od fíxistických statických interpretací k dynamickému pojetí vývoje Zemč. Dnes dominující paradigma geologie - tektonika litosferických desek - zdůrazňuje výrazné horizontální přesuny kontinentálních bloků. Za jejich hnací motor je považována tepelná konvekce v plášti Země, která je určována tepelnou výměnou mezi žhavotekutým jádrem Země a poměrně chladným povrchem. Teorie litosferických desek předpokládá, že konvekční tepelné proudy v plastické části zemského pláště vedou v místech vzestupných tepelných proudů ke vzniku divergentních rozhraní a v místech sestupných tepelných proudů ke vzniku konvergentních rozhraní litosferických desek Konvergentní rozhraní představují místa vrásnění, vulkanické činnosti, vzniku pohoří a kolize kontinentů Thompson aidTiirk: Earth Science and the Environment, 2fe Figuře 5.12 Spreading -sŕ ofcsff* center 3ubduction Ocean X4&&z£------------y> — zone tTMich ^"""^Z-^tl----- EURASIAN PLATE \ \ \7 3FH LANKA 39 million '"T \ ,,J,.U ""--■—r, j years ago /* V fnujTim A-" I---------J"""^--------»- r.^ million YMnogo / "INDIA" ,J Lpndmm ,' '^SRILAMKA ' J be=cr: Tip of Indian plate I MRI 1N PI dTF VsrV i>l ň ŕflŕk, J ta 7 I.ií hil inn Tŕtmrf n -rl Ftfftrcnicc point AFTER ^, —:"öv ^cCSľ^^ / HtgŤengnnp nnnt INDIAN PLATE y ö Hi mal av s* REbJ n g Tib tt an PI it taj ■^,^~ ""*—\-—~-—"rr^"""-^ ■► J*Wi pLAT£ Hlavní etapy vrásnění v prvohorách - čtvrtohorách Časová škála 245 Ma 545 Ma >c/3 c3 O > U CM >c/3 -i—> C/3 = o .a -i = o > -o *6« o -o o s "C .Q -i Vrásnění Variské vrásnění Kaledonské vrásnění Vznik Pangei Paleogeografie PANGEA WŕTŕíii i.iTiQ ____,__________LU____ Časová škála Vrásnění Paleogeografie Čtvrtohory 1,8 Ma fi ŕ V0Í W) o o 0> >'- o H 'S Plh 65 Ma 53 í^ :- o X o « b X ď ^ 0 :- Q iZ3 .s H 245 Mí L — Alpinské vrásnění Kimerské vrásnění The Western Collage Cordillera an collage of microplates and arcs - accreted during the Paleozoic and Mesozoic - terrains have different rock types and fossil assemblages that cannot be correlated - suspect terrains—fault-bounded regions thatSUSPECTTERRAN be correlated MmCJv MsmeoJc ■JĽfi-dii ■:■ i Air. inlJtan Uf;::c:r PmIkmIc andinasolr EŠ3 Mi^MvP^IgOZOIC »Ttlhyai Tjuullnlr hnin The Canadian Cordillera west of the Rockies is largely composed of displaced terranes, as are the easternmost sections of Siberia. Origins of these terranes are best Determined by the biogeographic affinities of the fossils in their sedimentary rocks. Cache Creek tropical faunas or Alexander subtropical to warm temperate faunas East edge North Cascades South Tethyan bryozoan faunas Gondwana 7)'v)Ava1on Peninsula Original craton (now told-and-thrust belt) laconic dements Blocks of deep-sea floor emplaced on continental crust during the Taconic orogeny Accreted in Early to Middle Ordövician time and deformed in Taconic orogeny Acadian elements Avalonian and related terranes Carolina terratie Terranes accreted in late Pateozoiq time Occurrence of Paradoxtdes trilobites / jA;)\Cape Hatteras ? Kilometers 40° Miles 200 \y~ / Area enlarged ) above Displaced terranes are island arcs or continent fragments that have been moved from one part of the world to another. The continental margins of E, W North America are largely composed of displaced terranes. Avalon Peninsula is part of a displaced terrane called Avalonia. Paradoxites and other Manuels River trilobites are European in their biogeographic affinities. "Viking Funeral Ship" paleobioaeoaraphic pattern________ Accretion of a buoyant fragment to a continent TIMET A buoyant oceanic or continental Fragment fragment is carried into a plate collision zone. Accreted terra ne TIME 2 The fragment is more buoyant than the subducting lithosphere, and is not subducted. TIME 5 The fragment becomes welded to the overriding plate. How Continents Grow: Accretion of continental fragments Fig. 20.12a Accretion of an island arc to a continent Continental crust TIME1 A plate carrying a continent subducts beneath an oceanic island arc. siand arc TIME 2 The continental crust is more buoyant than the subducting lithosphere and is not subducted with it. TIME 3 The island arc crust becomes welded to the island continent. Accreted terrane How Continents Grow: Accretion of island arcs Fig. 20.12b Accretion along a transform fault Transform fault Two plates slide past each other along a transform fault. ^.^, ^Terrane f Jt^w^^ >^ fragment TIME 2 A terrane fragment on plate B is carried along the margin of plate A. Terrane fragment Accreted terrane TIME 3 When the fault becomes inactive, the fragment becomes welded to plate A in a position distant from its original position. How Continents Grow: Accretion along transform faults Fig. 20.12c Accretion by continental collision and rifting Continental plate A TIME1 A plate carrying a continent subducts beneath another continental plate. 5ä TIME 2 The continent is not subducted, so two continents are welded together along a set of thrust faults. How Continents Grow: Thrust faults Accretion by continental collision/ rifting Accreted terra ne TIME 3 Later, rifting and seafloor spreading carry the continental plates apart, leaving a fragment of one continent welded to the other. Fig. 20.12d The Wilson Cycle Fig. 20.18 Composition Rock types 100 Felsic Intermediate (Granitic) (Andesitic) Granite/Rhyolite Diorite/Andesite Mafic (Basaltic) Ultramafic Gabbro/Basalt Peridotite/Komatiite Percent by volume \r 75% Increasing silica (SÍO2) \r Increasing potassium and sodium Increasing iron, magnesium and calcium 700°C Temperature at which melting begins Copyright © 2005 Pearson Prentice Hall, Inc. 40% 1200°C World Tectonic Provinces Tectonic provinces 180° 120° 60° 0° 60° 120° 180° 60S I___■___'___'___'___'___'___'___'___'___■___■___'___■___'___'___'___'___'___'___'___l Fig. 20.8a