Paleostress field reconstruction and revised tectonic history of the Donbas fold and thrust belt (Ukraine and Russia)

Abstract

In the WNW‐ESE Donbas fold belt (DF), inversion of 3500 microtectonic data collected at 135 sites, in Proterozoic, Devonian, Carboniferous, and Cretaceous competent rocks allowed reconstruction of 123 local stress states. Accordingly, four successive paleostress fields reveal the tectonic evolution of the DF. At the numerous sites that have been affected by polyphase tectonics, the chronology between local paleostress states (also paleostress fields) was established using classical criteria (crosscutting striae, pre‐ or post‐folding stress states, stratigraphic control). The oldest event is an extensional stress field with NNE‐SSW σ3. It corresponds to the rifting phases that generated the basin in Devonian times and its early Visean reactivation. Later, the DF was affected by a transtension, with NW‐SE σ3 characterizing Early Permian tectonism, including the development of the “Main Anticline” of the DF and the pronounced uplift of its southern margin and Ukrainian Shield. Two paleostress fields characterize the Cretaceous/Paleocene inversion of the DF, which was accompanied by folding and thrusting. Both are compressional in type but differ by the trend of σ1, which was first NW‐SE and subsequently N‐S. The discrete paleostress history of the DF allows a revised interpretation of its tectonic evolution with significant implications for understanding the geodynamic evolution of the southern margin of the East European Craton.

Crustal-scale pop-up structure in cratonic lithosphere: DOBRE deep seismic reflection study of the Donbas fold belt, Ukraine

“…The original basin center is characterized by a single dominant fold, called the Main anticline, which is almost symmetric with steeply dipping limbs (to 60Њ-80Њ). The Main and Southern synclines are adjacent to the Main anticline (Popov, 1963;Saintot et al, 2003). A thrust fault zone that dips (approximately) southward is developed near the northwestern margin of the Donbas fold belt.…”

“…Significant uplift of the southeastern part of the DnieprDonets basin occurred during Early Permian time, contemporaneously with salt movements within a transtensional tectonic setting. However, the main phases of shortening in the Donbas fold belt occurred during Late Triassic time and latest Cretaceous-early Tertiary time (Stovba and Stephenson, 1999;Saintot et al, 2003).…”

Late Devonian and Triassic basalts from the southern continental margin of the East European Platform, tracers of a single heterogeneous lithospheric mantle source

“…As no trace of a Variscan event is detected, that would confirm that the Permian event was not related to plate collision but to crustal transtensional reactivation (Gaetani 2000;Saintot et al 2003, synchronous with widespread regional uplift affecting the southern margin of the Eastern European Platform (as the Priazov massif in Stovba and Stephenson 1999). This uplift brought to the surface the buried greenschist Paleozoic succession and was likely related to regional rifting as in the Donbas (Stovba and Stephenson 1999;Saintot et al 2003;Shymanovskyy et al 2004). In that case, the latest orogenic event of the Scythian Platform might have been the late Proterozoic Baikalian development of an accretionnary belt .…”

“…The tectonic inversion of the Donbas is Mesozoic (Latest Triassic and Latest Cretaceous) and not Permian (Stovba and Stephenson 1999;Saintot et al 2003) as classically described and presented as such in figure 1. The Permian tectonics of the Donbas is tensional leading to a rift reactivation associated with salt diapirism Stephenson 1999, 2003).…”

Thermotectonic evolution of the Ukrainian Donbas Foldbelt revisited: new constraints from zircon and apatite fission track data

“…The subsurface structure of the basin was investigated using seismic profiles and boreholes (Chekunov et al , 1993; Ilchenko, 1996; DOBREfraction'99 Working Group, 2003; Maystrenko et al , 2003). In addition, the structural, tectonic and thermal evolution, basin inversion, and timing of magmatic activity were investigated by means of structural data, numerical modelling, vitrinite reflectance (VR) and radiometric dating (Privalov, 1998; Sachsenhofer et al , 2002; Saintot et al , 2003a, b; Alexandre et al , 2004; Spiegel et al , 2004). Consequently, significant progress has been achieved in the understanding of the geodynamic evolution of the DF and several models have been proposed by different working groups.…”