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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS011 Poster presentation 2133
Disjunctive-plicative lateral structures of Tien-Shan;their delineation and
role in pre-mesozoic geology of the region
Prof. Oleg Mordvintsev
Regional tematic Uzbekgeophysic IASPEI
In Central Asia, systems of breaking dislocation of various directions are widely developed, among them
are north-west, sub-latitude, to less degree sub-meridianal and north-east, as well as some other
directions. The structures of north-east strike have not been specially studied till present time. Analysis
of the material on subsurface geology of Uzbekistan, with some degree of confidence, let us assert that
they are not only one of the earliest disjunctive plicative structures in the region (age of start of
formation is Pre-Paleozoic), but even most of long-living active even till present. Nine such zones were
delineated within Western Uzbekistan, which divide the territory into the blocks essentially distinguished
by the character of magnetic field and gravity field, in some cases, differences in blocks minerageny
were established. In the north, they strike right up to Bolshoy Karatau ridge (Kazakhstan), in the west,
they come to Kopetdag (Turkmenistan). Materials on depth CDP showed their clear fixing on seismic
sections, besides, which is very important, from the beginning of entry (0.2 s) and till its end (4.5 s). In
order to define time of start of formation of these structures, their reflection in relief of crystalline
basement surface was followed, where they mostly show as flexure-fracturing zone (FFZ). The divided
zones have their own specific character of structural surface morphology. Upper to the section,
amplitude of movement on FFZ is leveling, and on Pre-Jurassic surface their tracing was conducted on
the zones of morphostructures contacts, as well as on distribution of magmatic magnetoactive objects
and differences in substance content of basement and intermediate structural stage. One of the most
important factors of depth of penetration of breaking dislocations into the Earth crust can serve the
character of distribution of average density of the Earth crust. Correlation of FFZ position with the
scheme of distribution of average density of the Earth crust showed presence of certain dependencies
(timing of local anomaly, passing through the areas of anomalies sign change). This emphasizes the
early age of start of formation of FFZ, that influences basement development in the period of its
becoming. Their show in Hercynian basement of Southern Tien-Shan and Bukhara Khiva region
sedimentary cover deposits demonstrates that they had kept their activity even in later periods.
Keywords: structures, disjunctive, field