Paleogene-early miocene deformations of Bukulja-Vencac crystalline (Vardar zone, Serbia)

Abstract

Low-grade metamorphic rocks of the crystalline of Mts. Bukulja and Vencac, which are integral parts of the Vardar Zone, are of Late Cretaceous age. From the Middle Paleogene to the beginning of the Miocene, they were subjected to three phases of intensive deformations. In the first phase, during the Middle Paleogene, these rocks were subjected to intense shortening (approximately in the E-W direction), regional metamorphism and deformations in the ductile and brittle domains, when first-generation folds with NNE-SSW striking fold hinges were formed. In the second phase, during the Late Oligocene and up to the Early Miocene, extensional unroofing and exhumation of the crystalline occurred, which was followed by intrusion of the granitoid of Bukulja and refolding of the previously formed folds in a simple brachial form of Bukulja and Vencac with an ESE-WNW striking B-axis. The third phase was expressed in the Early lowermost Miocene (before the Ottnanghian), under conditions of NE-SW compression and NW-SE tension. It was characterized by wrench-tectonic activity, particularly by dextral movements along NNW-SSE striking faults.

The balance between orogenic building and subsequent extension during the Tertiary evolution of the NE Dinarides: Constraints from low-temperature thermochronology

“…Further westwards, the dominant metamorphic conditions decrease to a greenschists to sub-greenschists facies that is typical for the main part of the Jadar block (see also Filipović et al, 2003;Marović et al, 2007aMarović et al, , 2007b.…”

“…4, Cvetković et al, 2007). Generally interpreted as Palaeozoic in age, these metamorphic rocks (the Bukulja-Venčac crystalline of Marović et al, 2007aMarović et al, , 2007b or the Birač formation of Trivić et al, 2010) display a composition that is significantly different when compared with the normal Palaeozoic protoliths that can be studied elsewhere in the Jadar block. Our field observations along the eastern flank indicate a Mesozoic metamorphosed sequence overlying the normal phyllites, sericitic schists and retromorphosed gneises that can be found on the western flank of Bukulja pluton.…”

“…Structurally, the mountains have an overall large-scale open antiformal geometry, created during the Pliocene-Quaternary inversion of the Pannonian basin that overprinted earlier Miocene normal faults dipping away from the mountains (Fig. 2, Marović et al, 2007aMarović et al, , 2007b.…”

“…A renewed phase of contraction is recorded by tilting of the Neogene deposits on the flanks of Fruška Gora, generally interpreted as being related to the Pliocene-Quaternary inversion of the Pannonian basin (e.g. Bada et al, 2007;Marović et al, 2007aMarović et al, , 2007b and references therein).…”

“…However, the effects of this inversion into the NE part of the Dinarides and its relationships with the predating extension in terms of exhumation are still a matter of debate (e.g. Marović et al, 2002Marović et al, , 2007aMarović et al, , 2007b. The research of this study aims to constrain the exhumation of the NE Dinarides by means of low-temperature thermochronology, analysing three key orogenic areas, i.e.…”