Insight in tectonic evolution of the Drmno Basin (SE Pannonian Superbasin)

Key words: seismic interpretation, asymmetric simple – shearing, core complex, flower structure, 
detachment

The Drmno Basin, local depression at the southeastern edge of the Pannonian Superbasin in Serbia,
represents a peri - Pannonian part of the Drmno - Zagajica – Plandište regional structure. Drmno 
Basin is formed by regional normal faulting during the Early Miocene extensional field in the Western 
Carpathian area, and is closely related with regional fault – Morava detachment, one of the prominent 
structures in this part of Serbo – Macedonian tectonic unit.
Although main tectonic regime of this part of the Pannonian Basin is already described in the earlier 
studies (Marović et al., 2007; Matenco and Radivojević, 2012), detailed observations of the tectonic 
conditions and deformations styles in the Drmno Basin are yet to be defined. In order to give more 
perspective to basin – scaled structures and their characteristics, we conducted detailed tectonic 
interpretation of available 2D and 3D seismic data, as well as geophysical logging and well core data
from the Drmno Basin. 
The sediments within the basin are deformed by a series of listric faults converging with Morava
detachment in the deeper parts of the basin. They usually have asymmetric simple shearing 
characteristics, with half – graben basin architecture and many synthetic, and few antithetic faults. 
On the northwestern part of the basin, metamorphic core complex Gaj has been uplifted by extension 
in the footwall block of the Morava detachment. At the younger part of basin fill strike slip structures 
can be recognized, pointing to basin deforming tectonic. The presence of negative flower structures 
can be connected with reactivation of predisposed fault surfaces as result of changed tectonic 
conditions, from extensional which created normal faults, to transtensional that created strike – slip 
movements.
Based on the fault tracking seismic attribute, that is utilized on 3D seismic cube of this area, main 
fault strike directions are recognized. The older, listric faults primarily have strike directions of east –
west and northeast – southwest. Younger, transtensional tectonic structures exhibit similar strike 
directions due to the reactivation of existing fault surfaces. 
All tectonic structures clearly indicate regional extensional field in the first tectonic phase, creating
accommodation space, which persisted during the basin thermal subsidence. The extensional phase 
is characterized by domination of listric faults created on the asymmetrical simple shearing model, 
as well as presence of core complex closely connected to detachment. Unlike other depressions in 
this part of the Pannonian Superbasin, the Early Miocene sediments in the Drmno Basin have 
significant thickness, indicating an earlier basin opening. The second, transtensional phase had 
influence on sediments in the upper part of the basin, creating negative flower structures.

References:
1. Marović, M., Toljić, M., Rundić, L. and Milivojević, J. 2007. Neoalpine Tectonic of Serbia. 
Serbian Geological Society, Belgrade.
2. Matenco, L. and Radivojević, D. 2012. On the formation ́ and evolution of the Pannonian 
Basin: constraints derived from the structure of the junction area between the Carpathians 
and Dinarides. Tectonics, 31, 2–31, https://doi.org/10.1029/2012TC003206