Cenozoic tectonics of Macedonia and its relation to the South Balkan extensional regime

Abstract

From Paleogene to Recent time, Macedonia was part of the South Balkan extensional region, the northern part of the Aegean extensional regime. Extension began in the middle to late Eocene in eastern Macedonia with the formation of a NNWtrending east-tilted half graben lying east of a forearc basin in central Macedonia. Following a short-lived period of localized shortening in late Oligocene to early Miocene time, a second period of Neogene extension began that continued to the present. Five cycles of Neogene extension are recognized, and associated sedimentation occurred in extensional basins of complex origins: (1) true graben, (2) tilted half graben, (3) pull-apart basins along strike-slip faults, (4) faulted silled basins filling topographic lows, and (5) complexly faulted basins of mixed fault origin. Neogene faulting and basin formation show a pattern that begins with both NNW-and EW-trending faults in mainly northern and eastern Macedonia progressing to younger times by dominantly NNW-to N-trending faults migrating into western Macedonia and E-W-and NW-trending faults dominant in eastern Macedonia. The origin of the Paleogene basins is interpreted to be related to trench rollback along the northern Hellenic trench and lateral spreading of thick hot crust within an arc. The short period of early Neogene shortening is related to the arrival of the small continental Kruja fragment at the subduction zone in Albania. The younger Neogene extension and westward migration of extensional faulting and basins is related to progressive rollback of the subducted slab in the northern Hellenic trench. The north-south extension in eastern Macedonia is related to the propagation of the North Anatolian fault in the northern Aegean Sea ca. 6 Ma and subsequent movement southward of south Balkan lithosphere north of the fault caused by the rapid SSW movement of the Aegean crust related to trench rollback along the southern Hellenic trench. The amount of southward extension within the Southern Balkan extensional region is much less than that in the Aegean south of the North Anatolian fault.

GPS results for Macedonia and its importance for the tectonics of the Southern Balkan extensional regime

“…for the great local relief along grabens, some of which contain lakes. Faults in northwestern Macedonia curve from their N-S strike to more E-W strike and are strongly influenced by the structural anisotropy of the crust in this region which shows the same change in strike (Dumurdzanov et al, 2005). In this part of Macedonia, the active Skopje graben trends E-W and is the locus of active faults of similar trend.…”

“…By early or middle Miocene time, extension within the Balkans was part of an evolving extensional system that is clearly part of the Aegean realm. During late Cenozoic time the pattern of extension within the Balkans continuously evolved and can be related to complex events in the roll back of the Hellenic subducted slab both to the south and to the west (Dumurdzanov et al, 2005). Nowhere is this more clear than in Macedonia where late Cenozoic E-W extension shows a progressive migration toward the west where roll back of the northern Hellenic trench occurred from Paleogene to recent time.…”

“…Our GPS studies in Bulgaria Nakov, et al, 2001;Kotzev et al, 2006-this volume) and Macedonia (this paper) have been an attempt to characterize present-day crustal movements and to relate these movements to studies of active faulting (Kotzev et al, 2006-this volume;Dumurdzanov et al, 2005). For Macedonia we used data from a 25-station GPS network surveyed twice, in 1996 by the State Department for Geodetic Survey, Republic of Macedonia, and the Bundesamt fur Kartographie und Geodasie (BKG) (Altiner et al, 1998), and in 2000 by the State Department for Geodetic Survey and MIT.…”

“…1; Burchfiel et al, 2000;Dumurdzanov et al, 2004Dumurdzanov et al, , 2005. Extensional tectonism has been the dominant mode of deformation within the southern Balkan region since early Cenozoic time, perhaps as early as Early or Middle Eocene time (Burchfiel et al, 2003;Kounov et al, 2004).…”

Cenozoic granitoids in the Dinarides of southern Serbia: age of intrusion, isotope geochemistry, exhumation history and significance for the geodynamic evolution of the Balkan Peninsula

“…9), volcanics and volcaniclastic basins, and additionally, non-volcanic sedimentary basins (e.g. Burchfiel et al 2000Burchfiel et al , 2008Dumurdzanov et al 2005). Some of the basins are clearly associated with normal faulting and they date the onset of Aegean extension during Middle to Late Eocene times (e.g.…”