Geomorphic criterion significance for deep-seated faults revelation at «covered» platformian regions (the case of Near-Caspian Depression)

Abstract

Taking the Near-Caspian Depression as a case study the author argues that 85 per cent of regional linear morphostructures (identified by means of structural geomorphological analysis) are reflected in geophysical fields and correspond to deep-seated faults, active during the neotectonic stage. In the region under consideration (as well as in other platformian areas) main geomorphic features connected with such faults are as follows: linear oriented river valleys, regional scarps and steep slopes, breaks in geomorphic levels of the same age, chains of landforms with similar orientation, distinct geomorphic boundaries. In the Caspian area oblique faults prevail, mostly SE strike (50%), the faults are very ancient, they cross the whole depression and continue further, out of its limits, About 20% of the faults are arcuate, they are found mostly at the East of the region and reflect Uralian tectonic structures. Structural geomorphic analysis of platformian regions with deep basement essentially increases the precision of deep faults tracing, allows estimating their neotectonic activity and aids in more objective evaluation of regional tectonics.