RECENT UNDERTHRUSTS OF TIANSHAN AND POSSIBLE MECHANISM OF THEIR ORIGIN

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RECENT UNDERTHRUSTS OF TIANSHAN AND POSSIBLE MECHANISM OF THEIR ORIGIN

The most wide spreadings In Tianshan have the ruptures of up thrust-over thrust type,which fall according to the"Leuks's rule" under the range and which have in their section the form of peak In connection with gravitation tearing of up throw side(allochthon).But beside them, there are existing ruptures falling to the peripheral of the range, which have low part of the slope hitched up.Every such rupture may be treated as normal(straight) up thrust.But how can we explain kinematics of upthrusts of the low parts of stope to the upper onesThe author adduces data testifying for the benefit of two staged formation of such rupturesAt the background of the depressions increase into the first stage there have been formed normal faults with falling down up throw sides(Fig.1-E-1) that was caused by the stretched efforts in connection with the presence of compact mantle under Tianshan. The second stage is while broadening the uplift zones(ranges)at the background of significant submeridinal tangential compression which was caused by the movement to the north of Indian lithosphere plate due to the early laying ruptures, there have been occurred the moving upof central uplift zones,broadening under slope segments(Fig.1-E-2).Such rupture, are qualified by the author as underthrusts, which are able to form the reversed fun bundles of block folds(Fig.2-B),in nature we can meet them very rare. In those places, where the main marginal faults zones presented by the underthrusts magnitudes of the earthquakes arelower then they are at the sections,which presented by the upthrusts-overthrusts. The author explaines this appropriateness by large zones division of underthusts formation wherethe sign of tectonic movements was changed at the recent stage.