LITHOSPHERE, 2002, No. 16, p. 81

A new interpretation of the evolution of extensive linear zones free of thick enough (hundreds of metres) Famennian sequences is based on the listric nature of step-forming faults in the Pripyat Trough. Across the listric fault zones the sequence changes in completeness, thickness and in the lithofacies of the intersalt Zadonsk-Petrikov and uppersalt Lebedian-Oressa deposits. This suggests that at the active phase of rifting with high general rates of downwarping and sedimentation the frontal parts of steps experienced ascending movements. Submarine tectonic scarps and chains of islands, where sediments did not deposited and/or were washed out had formed in the basin bottom relief.

A mechanism of relative upwarping and destruction of the frontal parts of steps was due to a listric character of the step-forming faults in the Pripyat Trough. The crustal block (step) sinking along a concave path resulted in its surface rotation about an axis parallel with the fault strike. The step warped down along the fault downthrown wall with simultaneous upwarping of its frontal part in the uplifted wall. The faulting process was accompanied by stage-by-stage discrete splitting of the frontal part of the step, and a series of intermediate blocks formed in the listric fault zone. The edge of the fault uplifted wall changed and migrated, and, subsequently, the bottom relief and sedimentation conditions in the fault-line zone changed too. A belt of destructed or not deposited sediments in the frontal part of the step increased simultaneously in width.

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