ANGARA-SELENGA IMBRICATE FAN THRUST SYSTEM
a:2:{s:4:"TEXT";s:135:"N.I. Akulov1, A.I. Mel’nikov1, V.V. Akulova1,2, M.N. Rubtsova1, S.I. Shtel’makh1";s:4:"TYPE";s:4:"html";}
a:2:{s:4:"TEXT";s:220:"1Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
2Irkutsk State University, ul. K. Marks 1, Irkutsk, 664003, Russia";s:4:"TYPE";s:4:"html";}
Keywords: Thrust, Jurassic sediments, Khamar-Daban terrane, Siberian craton
Abstract
We study Late Jurassic thrusting of the Archean craton basement over Jurassic sediments in Siberia, with the Khamar-Daban terrane as a rigid indenter. The study focuses on deformation and secondary mineralization in Archean and Mesozoic rocks along the thrusting front and the large-scale paleotectonic thrust structure. The pioneering results include the inference that the Angara, Posol’skaya, and Tataurovo thrusts are elements of the Angara-Selenga imbricate fan thrust system and a 3D model of its Angara branch. The history of the Angara-Selenga thrust system consists of three main stages: (I) detachment and folding of the basement under the Jurassic basin and low-angle synclinal and anticlinal folding in the sediments in a setting of weak compression; (II) brecciation and mylonization under increasing shear stress that split the Sharyzhalgai basement inlier into several blocks moving in different directions; formation of an imbricate fan system of thrust sheets that shaped up the thrusting front geometry, with a greater amount of thrusting in the front because of the counter-clockwise rotation of the Sharyzhalgai uplift; (III) strike-slip and normal faulting associated with the origin and evolution of the Baikal rift system, which complicated the morphology of the thrust system.
DOI: 10.15372/RGG2019125
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