Geologie na konci 20. století přešla od fixistických 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. konvekce th05_11 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 T40 CONVECT contvsocn288x157 Divergentní rozhraní Konvergentní rozhraní Litosferická deska Plastický plášť http://www.gly.fsu.edu/%7Esalters/GLY1000/Chapter5/Slide31.jpg Mantle plumes A mantle plume is asumed to exist where super-heated material forms at the core-mantle boundary and rises through the Earth's mantle. Independent of mantle convection. Orogens form at convergent plate boundaries. Accretionary orogens form at intraoceanic and continental margin convergent plate boundaries over a long period of time, and collisional orogens include those formed through continent continent collision. A special form of collisional orogens are intracratonic orogens which lie within a continent, away from an active plate margin. Accretionary and continent continent collisional orogens lie at plate margins and form through the subduction of oceanic lithosphere, with the former forming at sites of continuing subduction and the latter at the termination of subduction. Continent grow by orogenies Vytváření akrečních prizmat, kontinuální kolize s ostrovními oblouky, mikrokontinenty Fig. 3. Schematic cross-sections through (a) collisional, (b) accretionary and (c) intracratonic orogens. Vytváření akrečních prizmat, kontinuální kolize s ostrovními oblouky, mikrokontinenty Collisional and intracratonic orogens Collisional orogens form through continent continent collision. A special form of collisional orogens are intracratonic orogens which lie within a continent, away from an active plate margin Konvergentní rozhraní představují místa vrásnění, vulkanické činnosti, vzniku pohoří a kolize kontinentů nebo akreční orogeny FIGS8-2 S-XSECT EVEREST1 th05_12 con-con3 Fig. 14. Schematic cross-section across Tibet supposing a homogeneous thickening of 40% of the whole Qiangtang and Songpan-Ganze lithospheres (from (Goussin, 2019)). The age of the Ultra-K magmatism is mentioned above IYTS, Indus Yarlung Thrust system; BNS, Bangong suture; LSS, Longmucuo-Shuanghu suture; JS, Jinsha suture; KS, Kunlun suture, SQS, South Qilian suture. Collisiom of India with Tibet shortened Tibet core more than 1000km Cimmerides Paleozoic Asia margin It is the world's highest and largest plateau above sea level, with an area of 2,500,000 square kilometres (970,000 sq mi).[13] With an average elevation exceeding 4,500 metres Lateral Tibetan escape Intracratonic orogen The Tianshan is a type-example of ongoing lithospheric deformation in an intra-continental setting. It formed during the Paleozoic accretion and was rejuvenated in the Cenozoic, which might be a far-field response to the India-Asia collision. Fig. 11. Double-sided subduction pattern in the Pamir Hindu Kush of the western Himalayan syntaxis. (a) 3D model shows the spatial configuration of Pamir-Hindu Kush. The left-strike fault (red line) regulated the motion of two plates. (b) In Hindu Kush region, Indian plate subducted into Eurasian plate. (c) In Pamir region, Eurasian plate subducted into Indian plate. Cimmerian Hindikush, Pamir and VariscanTian Shan Accretionary orogens Deformation, metamorphism and crustal growth took place in an environment of on-going plate convergence. Accretionary orogens form at sites of subduction of oceanic lithosphere and consist of magmatic arcs systems along with material accreted from the downgoing plate and eroded from the upper plate. As subduction continues, island arcs, microcontinnets, continental fragments, arc-related basins, accretionary complexes, seamounts, continental fragments and ophiolites. and oceanic material may gradually accrete onto the continental margin. Outstanding examples of accretionary orogens is Central Asian Orogenic Belt. The Circum-Pacific region provides another outstanding examples of accretionary orogens during long lasting subduction of the ocean. The Central Asian Orogenic Belt (CAOB)is one of the world's largest Phanerozoic accretionary orogens which originated in Paleoasian ocean between the East European, Siberian m Karakum, Tarim and North China cratons Evolution of the Kazakh continent (orocline) The accretionary orogens of North and South American Cordillera are archetypical examples western_canada_terranes western_canada_terranes2 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. Figure 1: Terrane map of the western Canadian and Alaskan Cordillera including the Coast Mountains batholith. Jura-Cretaceous basinal assemblages are highlighted from southwestern BC into Alaska. Terrane in geology is defined as a fault-bounded block containing rocks that have a distinct geologic history compared with contiguous blocks, How Continents Grow How Continents Grow: Accretion of continental fragments Fig. 20.12a Fig. 9. Schematic section of accretionary prism showing sediment accretion through frontal accretion and basal accretion, and internal deformation of the wedge through contraction and extension (adapted from Kusky et al. 1997b). Particle paths are simplified net vectors and are drawn relative to backstop (see van Gool & Cawood 1994). Backstop is arc basement, and is composed of magmatic arc igneous rock or ophiolitic material. Fig. 20.12b How Continents Grow: Accretion of island arcs Mantle plumes Mantle plumes A mantle plume is asumed to exist where super-heated material forms at the core-mantle boundary and rises through the Earth's mantle. Independent of mantle convection. How Continents Grow: Accretion along transform faults Fig. 20.12c Figure 1 Distribution of the global Precambrian cratons. Modified from Sengor (1999), Wu et al. (2014). 422 pangea 372 Kaledonské vrásnění Variské vrásnění Prekambrium Vznik Pangei 545 Ma 245 Ma Časová škála Vrásnění Paleogeografie matte1986b_8 Hlavní etapy vrásnění v prvohorách - čtvrtohorách Mid_Jur Late_Cret Mio Kimerské vrásnění Alpinské vrásnění s. str. 245 Ma 65 Ma 1,8 Ma Časová škála Vrásnění Paleogeografie Čtvrtohory