Tevelev, Al. V., Tevelev, Arc. V., Kosheleva, I. A.

The Telbessian and Sudetic orogeny in Eastern Urals and Central Kazakhstan: case of comparative study.

The Telbessian and Sudetic tectonic events are well studied in Central Kazakhstan, and bellow they are comparing with firstly distinguished counterparts from Eastern Urals region. We examine the Zhaman-Sarysu Synclinorium (ZSS) in Central Kazakhstan and the Tarutino-Novonikolaevka Zone in Eastern Urals as typical areas of the Telbessian orogeny. In both, pre-orogenic formations are presented by the middle Ordovician to lower Llandoverian oceanic silicites and basalts of 1.5 to 2 km in thickness, overlaid continuously by the Silurian several km thick flysch. The sequence is more complete and complex in ZSS; it continues up to lower Givetian and includes the upper Silurian olistostrome. In both regions we mapped extremely intricate accretionary structure included piles of pre-folding nappes combined with syn-folding thrusts. Arc-shaped ZSS is thrusted overall outward; linear subvertical fabrics are more characteristic for Eastern Urals. Although the Late Telbessian orogenic molasse occurs only in Central Kazakhstan, the post-Telbessian evolution of both regions was rather similar. It started with the Famennian rifting indicated by the lump limestone of some hundred meters in thickness that overlies unconformably the Telbessian basement. The Sudetic orogeny occurs overall in both Central Kazakhstan (aside from the Late Hercynian areas) and Eastern Urals; it is expressed in unconformity occurring at the base of the Upper Visean. One of the most important type of the Sudetic basins include the rift-related dips, which have been turned during orogeny into the narrow fan-shaped or synform thrust-fold buildings. In both regions, the Sudetic phase was accompanied by tonalite plutons intrusion. Simultaneity of the early Hercynian tectonic events through Central Kazakhstan and Eastern Urals evidences more sufficient unity of the Mongolo-Ural folded belt then it was suggested earlier.

  The work is supported by RFFI, grants 96-05-65519, 96-05-65521.