Dehandschutter, B.,  Delvaux, D. & Boven, D. 1997. ‘The Teletsk tectonic depression (Altai): new kinematic data and chronological relations’. Mus. roy. Afr. centr. Tervuren (Belg.), Dept. Géol.-Min., Rapp. ann 1995-1996: 147-167.

Article in a scientific Journal / Article in a Journal

Lake Teletsk, situated at the northern end of the Central-Asian fold belt, in Altai, South Siberia, is a long, narrow and deep basin, surrounded by steep slopes which extend the basin up to 2800 meters. The lake is situated at the contact zone between two different geodynamic terrains. Analysis of the brittle structures, using remote sensing techniques together with field investigations, paleostress reconstructions and joint set analysis, revealed new indications on the tectonic nature of the Lake Teletsk graben. The collapse of the basin seems to be a very young process (less than 1 Ma). It appears that many of the recent structures evolved along pre-existing weakness zones, comprising a mylonitic shear zone and a suture zone. 40Ar/39Ar step-wise heating results on two biotite and one amphibole separate from mylonitized gneisses belonging to the shear zone, yield concordant apparent plateau cooling ages of 380 ± 5 Ma, suggesting rapid cooling. This timing corresponds to the emplacement of the granite-gneiss domes. Another sample of a mylonitized gneiss belonging to the same unit, however distinctly enriched in amphibole blasts, yields a discordant amphibole age spectrum with an average apparent plateau age of 260 ± 7 Ma. This age is thought to reflect a ductile shear event associated to the Permian thrust and strike-slip faulting, formerly described for the Teletsk region. Brittle reactivation appears to be limited to narrow zones and remains so far undated. Paleostress reconstructions allowed to differentiate three different stress states in the Teletsk Lake area. A first Paleozoic phase is post-ductile, while a last phase was active during the late Quaternary. The timing of the second tectonic phase remains uncertain, because of the limited amount of available constraining relations.