Conclusions Basement units Introduction Kinematic indicators
Field relations
Afyon zone metamorphics
(marbles, calcschists) Ivriz villageWNW ESE
Bozkir unit
(Mesozoic limestone within mélange) Bozkir unit
(Mesozoic limestone within mélange)
Afyon zone
marbles
Eocene sediments
recent covercoarse conglomerate marls, sandstones
N
S
Field relations close to Karagöl, where the Bolkardağ marbles (Afyon zone) are unconcormably overlain by a coarse conglemerate (reworking ophioltic and Bolkardağ debris, inset), overlain by Lutetian (Eocene) marls and sandstones that record (synkinematic) outcrop-scale thrusting.
Field relations close to Ivriz village, the type locality of the Ivriz detachment.
Marbles and calcschists of the footwall are in faulted contact with the Bozkir unit that contains non-metamorphic limestones. The fault surface is marked by a clear north-dipping slope along the Bolkar mountains.
Tuzgölü Marmara sea
Konya
Eskişehir Kırıkkale
Ankara
Tavşanlı Bursa
Nevşehir Kırşehir
Niǧde
Akdaǧmadeni
~150 Ma
~ 90 Ma ~ 65-60 Ma
~ 80 Ma
Afyon zone
(HP-metamorphism) Tavşanlı zone
(HP-metamorphism) Ophiolites
Ophiolites
re lic fo
rear c re
gion
detachment observed detachment suspected
Subduction and accretion of crustal fragments during the closure of the Neotethys
since the Mesozoic formed the Anatolian fold-and-thrust belt. In latest Cretaceous–Paleocene
time, a passive continental margin of the so-called Tauride block subducted into an E-W trending segment of the Neotethys subduction zone and underwent blueschist-facies metamorphism.
At present, blueschist rocks, locally known as the Afyon zone, are found exhumed in the overriding plate of this subduction zone, behind a younger thin-skinned fold-thrust belt of non-metamorphic rocks of the Taurides. Afyon zone metamorphics were previ- ously dated by Ar/Ar yielding 65-60 Ma cooling ages (Pourteau et al., 2013). The structures responsible for exhumation of the Afyon zone, as well as their age remain undocumented. ~65 Ma cooling ages of the Afyon zone metamorphics coincide with/shortly post-date peak pressure metamorphism and provide a maximum age for the onset of exhumation.
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88538853
Black Sea
Mediterranean Sea Aegean
Sea Kırşehir
Massif ABB ÇDB
Menderes Massif
Ulukışla Basin Ulukışla
Basin ÇB
Bitlis P O N T I D E S
TA UR I
D E S Izmir-Ankara-Erzincan Sutu
re zone
A R A B I A Sivas Basin
ADB HB
TB
28°E 32°E 36°E E°04
36°N 40°N
?
?
North Anatolian Fault
East Anatolian Fault Afyon zone
Tavsanli zone
Hellenic Trench
Cyprus Trench
0 200 km
Rhodope units Istanbul zone Aegean units
Cycladic blueschist/Dilek nappe Tripolitza/Beydaglari zone Basal units (Cyclades/Menderes)
Sakarya zone Cretaceous ophiolites Bornova Flysch
Bitlis massif Tavsanli zone
Alanya/Antalya nappes
Ören/Afyon/Bolkardag Lycian nappes Kirsehir massif
East Anatolian Flysch belt Arabia
Sedimentary basins
- Linear E-W trending structure >120 km
- Sheared metamorphic rocks of the Afyon zone in the footwall are tectonically juxtaposed against an ophiolitic mélange unit or unconformably overlain by Eocene sediments
- Marble mylonites of the Ivriz structure are intruded by a granitoid, previously dated at 56 Ma. The mylonites are recrystallized and the granite is not sheared.
To the north of the Bolkar mountain range lies the Ulukışla basin. Its Uppermost Cretaceous sediments record synsedimentary N-S extension, in a similar direction as indicated by stretching lineations observed on the Ivriz structure.
Juxtaposition of metamorphic against non-metamorphic rock
Decrease in temperature of the latest deformation towards the contact
Structure is an extensional detachment that accommodated exhumation from at least lower greenschist facies conditions to the surface.
~65 Ma cooling ages of the metamorphics coincide with/shortly post-date peak pressure metamorphism and provide a maximum age for
the onset of exhumation. Simultaneous syn-sedimentary N-S extension in the Ulukışla basin shows that the forearc was already in extension at that time.
Sediments sealing the detachment demonstrate that the detachment was no longer active in Lutetian time (49-40 Ma). The 56 Ma intrusion of the Horoz granite into the marble mylonites and absence of post-intrusion mylonites show that by 56 Ma, the Afyon zone metamorphics were already at upper crustal, brittle levels.
The Ivriz detachment is a regionally important structure and potentially one of the largest extensional back-arcs in the Mediterranean region.
The temperature of the last defor- mation decreases towards the brit- tle cataclastic part of the fault.
Burç subbasin
Bolkardağ (Afyon zone) Niğde Massif
−4000
−2000 0 2000 4000 6000 [m]
0 5 10 15 20 25 30 35 40 45 50
Distance [km]
−4000
−2000 2000 0 4000 syn-rift (Upper Cretaceous-Paleocene)
syn-contraction (Eo-Oligocene) post-rift (Eocene)
Bolkardağ (Afyon zone) Niğde Massif
Aktoprak subbasin
Central Anatolian ophiolites
N S
In the west, the fault zone is dipping ~40-50 de-
grees N. Towards the east, the foliation becomes steeper to subvertical. The Ivriz structure be- comes incorporated in the steep limb of a major, km-scale north-verging fold of Eo-Oligocene age.
Kırşehir massif Afyon
Taurides
resulting lineationN-S extension
E-W extension
Neoteth
ys Oceanic
P
late system Anadolu P
late
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future Anatolia future Anatolia
92 Ma - L ate C
retaceo
