New data on the tectonics of the Adych-Taryn fault zone (Eastern Yakutia)

Abstract

In the central part of the regional Adycha-Taryn fault (ATF) zone, separating the Adycha-Elginsky and Nersky anticlinoria (Verkhoyansk-Kolyma folded area), three stages of tectonic deformation in the Upper Triassic rocks have been established. In the first stage, thrusts and folds of the northwest strike formed. Deformations of the second stage are represented by folds with steep hinges and associated sinistral strike-slip faults. The third stage of deformation marked by the formation of dextral strike-slip faults is also presumed. It is established for the first time that the intensity of tectonic deformations varies both along and across the ATF. The intensity of deformations decreases from northwest to southeast on the southwest flank of the ATF zone. On its NE flank, the deformation intensity gradually increases in the same direction. The orientation of paleostress axes responsible for the formation of tectonic structures in the study area was determined for the first time. Folds and thrusts of the first deformation stage were formed under NE-directed subhorizontal compression. The formation of sinistral strike-slip faults and associated folds of the second stage was related to subhorizontal compression in sublatitudinal direction. Subsequent dextral strikeslip faults resulted from NW-directed subhorizontal compression and NEoriented subhorizontal extension.