Derya Gürer*, Douwe J.J. van Hinsbergen, Liviu Matenco, Fernando Corfu, Murat Özkaptan, Cor Langereis
Department of Earth Sciences, University of Utrecht, The Netherlands
Department of Geosciences & Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Norway Department of Geological Engineering, Middle East Technical University, Ankara, Turkey
*m.d.gurer@uu.nl
Introduction Structure and field kinematics Implications for Anatolian Tectonics
Subduction dynamics of Central and Eastern Anatolia since the Late Cretacous reconstructed from sedimentary basins in the Neotethyan suture zone
Neoteth
ys Oceanic
P
late system Anadolu P
late
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future Anatolia future Anatolia
92 Ma - L
ate Creta ce
ous
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88538853
Black Sea
Mediterranean Sea Aegean
Sea Kırşehir
Block Menderes
Massif
Ulukışla Basin Ulukışla
Basin ÇB
Bitlis P O N T I D E S
T A
U R I
D E S Izmir-Ankara-Erzincan Sutu
re zone
A R A B I A Sivas Basin
28°E 32°E 36°E E°04
36°N 40°N
?
?
North Anatolian Fault
East Anatolian Fault Afyon zone
Tavşanlı zone
Hellenic Trench
Cyprus Trench
0 200 km
Latest Cretaceous
N-S directed extension (present day orientation):
small offset normal faults with associated striae at southern margin close to contact with Bolkar Moun- tains (arrows)
Eocene-Oligocene
N-S directed compression (present day orientation):
reverse faults with associated striae (arrows) and fold hinges (dots) at the southern margin of the basin, close to the contact with the Bolkar Mountains. Deformation becomes less intense from south to north
Paleocene
E-W directed extension (present day orientation):
large offset normal faults
with associated striae (arrows) located close to the contact
with the Niğde Massif (north- ern margin of basin)
Çiftehan Fm
Alihoca ophiolite Aktaştepe Fm Halkapınar Fm
Ulukışla Fm Hasangazi Fm Bolbeztepe Fm
Kabaktepe Fm Aktoprak Fm
Burç Fm
continental deposits
Campanian - Maastrichtian Middle - Late Campanian Paleocene - Eocene Eocene Late Oligocene - Early Miocene Miocene - Pliocene Pliocene
Paleocene - Early Eocene (Late Maastrichtian - Late Paleocene) top of volcanics dated
at ~56.5 Ma
lower part of volcanics dated at ~59.5 Ma
gabbro dated at ~92 Ma
v v v
v v
500 m
−1000
0
1000 2000
Elevation [m]3000
Distance [km]
−1000 0 1000 2000 3000
0 5 10 15
SW NE
Anadolu Plate system
Eurasia fixed 70 Ma
V V V V
V V
VV
V
V
V
V
V
V V
V V
V
V
V
V V
V
Eurasia fixed 30 Ma
V
V
V
V V suture
V
V
V
V V
V V
V
suture
Anadolu Plate system
Africa
Eurasia fixed 30 Ma
V V
V
V
V
V
V V V V
V
V V V
V
V V V
V
Eurasia fixed 60 Ma
V
V V
V
V V
V
V V
V
V
V
V
V
Anadolu Plate system
Eurasia fixed 60 Ma
suture
207 235 207 235
0.00872 0.00876 0.00880 0.00884 0.00888 0.00892
0.01430 0.01434 0.01438 0.01442 0.01446 0.01450 0.01454 0.01458
0.00914 0.00918 0.00922 0.00926 0.00930 0.00934
0.00925 0.00927 0.00929 0.00931 0.00933 0.00935
0.055 0.057 0.059 0.061
0.093 0.095 0.097 0.099
0.059 0.060 0.061 0.062 0.0602 0.0610 0.0618
206 Pb/238 U
Pb/ U Pb/ U
206 Pb/238 U
Volcanics (top) Gabbro (ophiolitic basement)
Sample UK9.4 Sample UK94
Age = 92.2 ±0.3 Ma MSWD = 0.38 Probability = 0.54
Age = 59.6 ±0.3 Ma MSWD = 4.0 Probability = 0.044
Age = 59.7 ±0.4 Ma MSWD = 10.6 Probability = 0.001 56.0
56.0 56.2 56.2 56.4 56.4 56.6 56.6 56.8 56.8 57.0 57.0 57.2 57.2
92 92
93 93
59.0 59.0
59.4 59.4
59.8 59.8
59.8 59.8
Age of ocean floor formation above a spreading centre (SSZ-type signa- ture): 92 Ma
Base of volcanics offset by normal faults 59 Ma
Latest stage of extension is sealed by volcanics of 56 Ma
E-W extension prevails until 56 Ma
−1000 0 1000 2000 3000 Elevation [m]
−1000 0 1000 2000 3000 4000 5000
10
5 15
v
v v vv v v v
v v v v v v
vv v
vv
v v
+ + + ++ +
+ + +
+
+ +
+ +
−1000 0 1000 2000 3000 Elevation [m]
−1000 0 1000 2000 3000 4000 5000
0 5 10 15 20 25 30
4000 5000
59
UK9.4
UK94
UK5.1
UK14.28 UK1.1
Pozantı
Çamardı
Ulukışla
Halkapınar Ereğli
Postallı
Ardıçlı
Aktoprak
Alihoca Gümüş
Ovacık
Burç
BASIN UNITS
Burç Fm Miocene-Pliocene continental deposits Pliocene
Horoz/Elmalı/Gedelli Eocene INTRUSIONS
Aktoprak Fm Oligo-Miocene
Hasangazi Fm Middle - Late Eocene Bolbeztepe Fm Middle - Late Eocene Kabaktepe Fm Oligocene
Ulukışla Fm Early Paleocene- Middle Eocene Alihoca/Pozanti ophiolites Upper Cretaceous
Bolkardağ unit (Afyon Zone) Devonian - Upper Cretaceous
Bozkir unit (Afyon Zone) Upper Triassic - Upper Cretaceous
Aladağ (Taurides) Upper Devonian - Upper Cretaceous Niğde Massif (Kırşehir Block) Paleozoic - Mesozoic
Halkapınar Fm Paleocene - Early Eocene
Çamardı Fm Late Cretaceous - Late Paleocene Aktaştepe Fm Campanian-Maastrichtian
Çiftehan Fm Middle-Late Campanian
town village
83 42
thrust fault normal fault synclinal axis anticlinal axis bedding
(dip direction/dip)
dated sample
BASEMENT UNITS
Ecemiş fault zone
Bolkardağ Mts.
Aladağ Mts. Niğde massif
a.
c. d.
b.
b.
E W
W E W E
N S
A
A’
B
B’
C
C’
AR 2 Late Cretaceous - south
BU 1 & 2 & YK 4 Late Paleocene - north
HP 1&
3&6 Paleocene - south EM 3
?Early Eocene - centre
CP 3 Late Miocene - north CP 2
?Middle Miocene - north
TT 1 Late Eocene - centre
?Eocene - south HP 3
?Eocene - south
AT 2 &
3&4 Oligocene - south
Rotations Around 30 degress counter-clockwise rotation throught the basin
= correcting for this rotation would result in a more WNW-ESE-oriented basin geometry
Subduction and accretion of crustal fragments during the closure of the Neotethys since the Mesozoic formed the Anatolian fold-and-thrust belt. Sedimentary basins overlying key locations between accreted domains of different metamorphic grade may help to quantitatively kinematically restore subduction evo- lution, and to identify timing, directions and amounts of post-accretionary extension, shortening and strike-slip faulting.
The Ulukışla basin straddles and is sandwiched between the HT-LP Kırşehir Block (KB) to its north, and the HP-LT Bolkardağ/Afyon zone (BD) to its south and lies on ophiolitic basement. At its southern margin a series of small-offset faults consistent with an early phase of (late Cretaceous-Paleocene) N-S extension, may have been associated with extensional exhumation of BD. Close to the contact with KB, a series of large-offset listric normal faults compatible with E-W extension offsets sediments and the base of newly dated Paleocene volcanics, showing that E-W extension prevailed until beyond 56 Ma. This is likely geneti- cally linked to regional extension in the KB and overlying basins. Subsequently, N-S directed contraction led to E-W striking folds and thrusts, to back-thrusting of the BD over the basin, probably in Oligocene time, and coeval left lateral strike-slip motion along the Ecemiş fault (EF) at the eastern basin margin.
At 70 Ma, we go from 2 parallel north-dipping subduction zones to 1. The remaining southern one has a kinked geometry with N-S and E-W segments. Deformation focuses on the central segment, causing rotations in the Kırşehir Block.
Eastward migration of triple junction through time.
At 65 Ma, the volcanic arc in western Anatolia shuts down, the Kırşehir Block collides with the Pontides, leading to oroclinal bending.
Peak metamorphism in the of the passive margin of the Taurides at 70-65 Ma.
At the same time the Ulukışla fore-arc basin forms north of the Taurides segment accommodated by N-S extension.
60-56 Ma extension in tlinked to the Kırşehir segment.
At 30 Ma onset of regional N-S shortnening, folding and thrusting, and development of angular unconformities in the Ulukışla bbasin. Deposition of the Aktoprak molasse basin.
Onset of sinistral movement along the Ecemiş Fault zone (total displacement >65 km). Transpressional deformation along the fault zone leads to reburial of the southern tip of the Kırşehir block (Niğde massif) and associated structures in the basin.
Conclusions
Africa Eurasia
TN TS
> 65 Ma (Late Cretaceous) extension
TN , M TN , M TN , M
compression extension
, M
~ 50-40 Ma (Eocene) tectonic quiescence
~ 40-20 Ma (Eocene-Oligocene) shortening
<20 Ma (Miocene) strike-slip Stage 1
TS
TS TS
TS Stage 2
Stage 3 Stage 4
M
N S
Eurasia
and M = mantle
fixed Anadolu
1) Coeval N-S and E-W extension in the latest Cretaceous to Paleocene created ac- commodation space on the overriding plate.
2) Extensional structures were reactivated during N-S directed thrusting and ultimately lead to continental subduction and accre- tion of material from downgoing to overrid- ing plate.
3) The geology of the region is the surface expression of two roughly parallel subduc- tion zones, one below the Pontides, and a single intra-oceanic subduction within the Neotethyan domain to its south.
4) We name the oceanic plate system in be- tween the two trenches “Anadolu”, after the Turkish word for Anatolia.
We provide kinematic and geochronological data from a relic forearc region in the Anatolian domain. It overlies an intra-oceanic subduction zone that initiated around 100 Ma. In the forearc sediments we find multidirectional exten- sion that results from N-S and E-W striking segments of an initially kinked subduction zone that resulted from ridge and transform inversion, respectively.
N S
N
S
