Evidence for Seismicity of the Southeastern Altai Region during the Quaternary

摘要

The present-day morphology of the Altai orogen, its southeastern segment included, started forming in the early Neogene. The main orogenic phase began in the Late Pliocene. It is clear that mountain forming processes particularly during the Quaternary should have been accompanied by high seismicity. Until recently, its consequences were evident only from Holocene seis-mogenic macrodislocations: landslides, rock falls, scarps, extended troughs. Older intervals of the Quaternary section remain uninformative in this respect. Only discovery of seismites representing peculiar deformation structures reflected in sedimentary sequences of the southeastern Altai region [1] offered the opportunity for defining consequences of pre-Holocene seismic events. The main purpose of this study is to reveal a correlation between seismites and stratigraphic succession of Quaternary sediments in the region for determining periods of its paleoseismicity. In addition, morphological features and formation mechanisms of seismites are considered.