Reconstruction of unbalanced cross-section of Flysch Carpathians
DOI:
https://doi.org/10.26565/2410-7360-2026-64-04Keywords:
folds belts, palinspastic reconstructions, unbalansed crossection, fold-and-thrust deformations, buckling, uncoaxial flow, numerical modeling, stressed state, Flysch CarpathiansAbstract
The purpose. Making up on an example of Flysch Carpathians numerical experiments in sphere of palinspastic restoration of fold-and-thrust orogens without entering any essential changes into initial geological cross-section or structure scheme, that first of all concerns folds.
Method. Investigations are based on application of most general, conceptually neutral mechanisms of folding: bending and uncoaxial flow. Cross-section reconstruction is executed by means of consecutive removal of the specified deformations, and indemnifications of thrust movings. The decision of a direct problem of reconstruction is based on numerical modelling of folding in a sedimentary cover; faults displacements were artificially entered as independent components of the general process of viscous-plastic deformations.
The results. Full restoration of Ukrainian Flysch Carpathians for the central cross-section of Krosno and partly Skiba zones is made, the size of the general 4-times orogenic horizontal reduction is obtained, the approximate configuration of initial basin profile is restored. No contradictions are finding by comparison of the received results with the data of reconstruction by the balansed profiles, but addition to them is possibility to tracking evolution of presented folded structures. In the direct problem series of numerical experiments on reproduction typical asymmetric flexural folds, fold-thrust paragenesis, and also the vertical symmetric folds are maid conditioned by horizontal reduction of a cover. It is shown that for their formation presence of a competent layer and the set conditions of sliding at a base is necessary. On the basis of the received experimental data approximate restoration of process of formation typical tructural forms for the central crossing of Krosno zone has been made.
Scientific novelty. It is shown, that for palinspastic reconstruction of folded belt structural profiles can be used in that kind in what they are presented by authors, without preliminary processing by balancing. The offered program of reconstruction is the antithesis to methodology of the balanced cross-sections which can be followed by the synthesis, she itself is attempt to balance modern structural-tectonic approaches. Folds numerical modelling gives a full spectrum of characteristics of deformation process: angles and sizes of the main stresses, sizes of deformations of compression and shear, etc., that allows to spend effective comparison of experimental conclusions with data of natural objects studying. The informal maintenance of constructions on the basis of unbalanced profiles consists in possibilities to attracting various mechanisms of deformation of a sediments and free selection of geodynamic models. Except dominating for today accretion model connected with subduction of a basins crust, ideas about realisation of gravitational instability and collisional compression, and also their combination may to be applied; consideration of folding in all variety of forms gives the grounds to attraction of these conditions to interpretation of a tectonic structure of Carpathians.
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