Details of the abstract
Title of paper | Donbas geoelectrical structure |
List of authors | Rokityansky, I.I., Tereshyn, A.V. |
Affiliation(s) | Subbotin Institute of Geophysics of the National Academy of Sciences of Ukraine, Kiev, Ukraine |
Summary | Donbas was formed by Late Devonian rifting of the East European Craton. Then subsidence and sedimentation formed 15-km thick Carboniferous deposits. The next long event was folding. Then inversion lifted the folded Donbas and subsequent erosion exposed the Carboniferous coal-bearing strata. Dominated strike of the Donbas structures is WNW-ESE. Deep electrical conductivity was studied by the methods of magnetic variation profiling (MVP) and magnetotelluric sounding (MTS). The MVP data at long (5-180 min) periods reveal the intense Donbas electrical conductivity anomaly (DECA) which runs along the main anticline of the folded Donbas and continues in DDB and Karpinsky swell (Figure 1). Interpretation conducted according to ideas described in (Rokityansky 1982). DECA parameters obtained by MVP: Profile graphs of the anomalous field give an estimate of the maximum possible depth of the anomalous currents center h=18±2 km. Frequency response maximum Тo≈3600 s yields the total longitudinal conductance G = (8±2)×10^8 S×m. Mapping the anomaly axis (Figure 1) and effective width L=36 km estimation also reliably made by MVP. 70 MTS at periods 0.1-3000 s yield: the upper ≈0.5 km thick layer have, as a rule, resistivity in the range of 5—50 Ohm·m. Deeper low resistivity objects are located in two conductive stripes, which upper edge varies from 0.3 to 5 km. The stripes are parallel to the DECA axis and considered as part of DECA. A very large value of G leads to assumption that the anomalous body extends to considerable depth (Figure 2). DECA axis spatially coincides with intense (up to 90 mW/m^2) deep heat flow anomaly. This fact suggests that the nature of the DECA lower part can be a partial melting. Geoelectric results support the idea of the modern tectonic activation in Donbas developed by V.V. Gordienko. |
Session Keyword | 3.0 Exploration, Monitoring and Hazards |
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