Yenisey Fold Belt

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Coordinates: 59°N 94°E / 59°N 94°E / 59; 94 The Yenisey Fold Belt is a fold belt in Russia that divides the Siberian craton from the West Siberian basin, extending about 700 kilometres (430 mi),[1] with NW-SE strike. This belt is divided into northern and southern regions by the Angara fault which has left slip.[2] Much of the rock was formed by Neoproterozoic accretion.[1]

North of the fault, the area is made up of thrust sheets[2] divided into three primarily Neoproterozoic terranes, the East Angara, Central Angara and the Isakov.[1] The Isakov Terrane is a series of imbricated volcanic and sedimentary units containing ophiolite, which is underlain be volcanics, metamorphics and sedimentary rock. Unconformably overlying it is the Vorogovka group, a series of basins which were thrust over the Isakov.[3] This terrane overlies the Central Angara terrane, having been thrust eastward over it.[2] The Central Angara Terrane is intruded by alkaline granites with NNW trend in the elongated bodies. The Eastern Terrane lacks signs of magmatism,[4] instead it is made up of overriding late Neoproterozoic deposits above older groups, most of which are intruded by granites.[3]

South of the Angara fault, there are two allochthonous units. One is the Angara-Kan micro-craton, which is sometimes considered separate from the fold belt.[4] This terrane is formed of Paleoproterozoic granulite amphibolite facies,[2] and the other is the Predivinsk terrane which is mostly Neoproterozoic island-arc accretion.[1] The Angara-Kan terrane also includes two pyroxene plagioclase and one garnet-biotite-sillimanite-cordierite gneisses.[2]

The late Riphean strata of the Sukhopit, Tungusik, and Oslyan series formed on along a continental margin of open ocean followed by a back-arc basin from 1050-1150 million years ago.[5] From around 860-880 MA until 700-630 MA, the collision of many of the terranes occurred during the Baikal orogeny, which was the period of much of the accretion, thrusting, and metamorphism.[6] This period is also when granitic intrusions occurred.

References[edit]

  1. ^ a b c d Vernikovsky, Valery; Vernikovsky; Kotov; Sal'nikova; Kovach (2003). "Neoproterozoic accertionary and collisional events on the western margin of the Siberian craton". Tectonophysics 375: 147–168. Bibcode:2003Tectp.375..147V. doi:10.1016/S0040-1951(03)00337-8. Retrieved 28 Oct 2012. 
  2. ^ a b c d e Vernikovsky, V.A.; Vernikovskaya, A.E.; Pease, V.L.; Gee, D.G. (2004). "Neoproterozoic Orogeny along the margins of Siberia". The Neoproterozoic Timanide Orogen of Eastern Baltica (30): 233–248. 
  3. ^ a b Linnemann, Ulf (2007). The Evolution of the Rheic Ocean. GSA. Retrieved 10 Feb 2013. 
  4. ^ a b Khiltova; Pleskach (1997). "Yenisey fold belt". In Rundqvist; Gillen. Precambrian Ore Deposits of the East European and Siberian Cratons. Elsevier Science. Retrieved 10 Feb 2013. 
  5. ^ Ulmishek, Gregory (2001). "Petroleum Geology and Resources of the Baykit High Province, East Siberia, Russia". USGS. Retrieved 27 Oct 2012. 
  6. ^ Gertner, Igor; Tishin, Platon; Vrublevskii, Vassily; Sazonov, Anatoly; Zvyagina, Elena; Kolmakov, Yuriy (Oct 2011). "Neoproterozoic Alkaline Igneous Rocks, Carbonatites and Gold Deposits of the Yenisei Ridge, Central Siberia". Resource Geology 61 (4): 316–343. doi:10.1111/j.1751-3928.2011.00170.x. Retrieved 28 Oct 2012.