Previously Unrecognized Now-Inactive Strand of the North
Anatolian Fault
in the Thrace Basin
Dogan Perincek
The North Anatolian fault
is a major 1,200 km-long transform
fault
bounding
the Anatolian plate to the north. It formed in late middle Miocene time as a
broad shear zone with a number of strands splaying westward in a horsetail
fashion. Later, movement became localized along the stem, and the southerly and
northerly splays became inactive. One such right-lateral, now-inactive splay is
the west-northwest-striking Thrace strike-slip
fault
system, consisting of three
subparallel strike-slip faults. From north to south these are the Kirklareli,
Luleburgaz, and Babaeski
fault
zones, extending ±130 km along the strike. The
Thrace
fault
zone probably connected with the presently active northern strand
of the North Anatolian
fault
in the Sea of Marmara in the southeast and m y have
joined the Plovdiv graben zone in Bulgaria in the northwest.
The Thrace basin in which the Thrace fault
system is located, is Cenozoic
with a sedimentary basin fill from middle Eocene to Pliocene. The Thrace
fault
system formed in pre-Pliocene time and had become inactive by the Pliocene.
Strike-slip
fault
zones with normal and reverse separation are detected by
seismic reflection profiles and subsurface data. Releasing bend extensional
structures (e.g., near the town of Luleburgaz) and restraining bend
compressional structures (near Vakiflar-1 well) are abundant on the
fault
zones.
Umurca and Hamitabad fields are en echelon structures on the Luleburgaz
fault
zone.
The Thrace strike-slip fault
system has itself a horsetail shape, the various
strands of which become younger southward. The entire system died before the
Pliocene, and motion on the North Anatolian
fault
zone began to be accommodated
in the Sea of Marmara region. Thus the Thrace
fault
system represents the oldest
strand of the North Anatolian
fault
in the west.
AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.