Features of the formation of the SE Dnieper-Donetsk basin (data of a direct and inverse 2-D tectonic modeling)
© Stovba S.N., Maistrenko Y.P.
Forward and reverse modelling of structure and stratigraphy have been used to investigate the syn-rift (Late Devonian) and early post-rift (Carboniferous) evolution of the SE Dniepr - Donets basin. Modelling was made with and without taking in consideration the withdraw of the Devonian salt on the surface during the salt stock formations. The huge thickness of Carboniferous deposits can be explained by actions of three processes superimposed on each other: post - rift thermal subsidence, withdraw of the Devonian salt from the mother layer during phases of salt diapir activity, and regional subsidence of the East - European platform. The action of other tectonic and nontectonic process is not necessary to explain it. The forward syn-rift modelling using the flexural cantilever model of sedimentary basin formation has allowed us to predict the total syn-rift extension across the DDB of approximately 65 km with a maximum b stretching factor of 2,4. The modeled syn-rift Moho elevation is 15 km. The present - day one is predicted to decrease to 4-6 km due to thermal subsidence and basin fill. In the axial zone of the southeastern part of the DDB the thickness of the Devonian syn-rift sequence could reach 7,5 km at the end of the rift stage. It is by 3-3,5 km more than the present - day one. Decreasing of the sequence thickness happened due to the loss of the Devonian salt that outflowed on the surface during post-rift phases of salt diapir activities in early Visean, in the middle of Serpukhovian and in the Early Permian. The withdraw of salt from the mother layer caused an addional accommodation space which resulted in the formation of to 1,5-1,7 km of the total thickness of the lower carboniferous sediments.