Lithosphere heterogeneity of the Dnieper-Donets basin and its geodynamical consequences. II part. Geodynamics interpretation
Journal Title: Геодинаміка - Year 2017, Vol 23, Issue 2
Abstract
Aim. Geodynamic interpretation of previously obtained 3D density and magnetic modeling results, and data on consolidated crust fault tectonics of the Dnieper part of Dnieper-Donets basin (DDB) in the light of its formation mechanism. Methodology. A detailed analysis of the structural relations of the sedimentary strata structure, crystalline crust block structure, and its fault kinematics in the Ukrainian shield (USH), Voronezh massif (VM) and their slopes during the late Proterozoic taking into account the seismotomography data for the deeper lithosphere horizons. Results. Features of the structure and the material composition of the consolidated crust DDB were formed as a "summary effect" of passive and active stages of rifting. Last and most likely, is the result of multi-phase linear elongated mantle diapirs (asthenolith). They correspond to the heterogeneity of modern subcrustal mantle and crust segmentation. Devonian DDB rift formed on the north-western suture zone separating the Precambrian basement domains of different composition and structure. The rift opening in the passive stage occurred along an ancient suture zone from the south-east to north-west with participation of dextral and rotational movements of the lithosphere blocks. The heterogeneity of the Precambrian crust and the right shears along inter-segment and latitudinal faults, in combination with rotational movements, caused the non-uniform stress fields and the formation of new inter-segment faults. Disappearance of the "granite" layer and partly decreasing thickness of "diorite" were the result of passive rift formation stage. The main factors of this active stage include the activation processes of the asthenosphere, crust reprocessing, bottom erosion, formation of velocity and density heterogeneities of the lithosphere, and its bottom relief. Crystalline crust of the DDB has a substantially greater basicity compared to surrounding structures. Its thickness increases from segment to segment from the North-West to the South-East, and is accompanied by a decreasing of the lithosphere thickness. The maximum contribution crust-mantle mixture to the basalt layer thickness is a sign of their activation. The asymmetric structure of the lower crust and mantle lithosphere indicate the presence of the inclined disruptions within the lithosphere, as part of the extension mechanism of the crust and mantle material penetration during the rifting. Formation of the sedimentary layer and its fault tectonics are caused by the structure of the crystalline crust. Originality. For the first time the heterogeneity of the lithosphere are considered as indicators of different stages of the rift formation (the initial passive and subsequent active). The role of shear deformations and rotational movements in the forming and development of the rift are shown. Practical significance. Established heterogeneity relations of the different layers of the lithosphere can be used to assess oil and gas prospects in the region.
Authors and Affiliations
V. I. Starostenko, I. K. Pashkevich, I. B. Makarenko, P. Ya. Kupriienko, A. S. Savchenko
Keywords
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- EP ID EP455773
- DOI 10.23939/jgd2017.02.083
- Views 79
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