Open Session - SWISS GEOSCIENCE MEETINGs

8
Symposium 1: Structural Geology, Tectonics and Geodynamics
The material was very hard to deform at lower temperatures (700-750°C) with a higher strain rate (≈3x10 -3 s -1 ). At temperatures
700-777°C and strain rate 3x10 -4 s -1 , the aggregate did not react to produce K-feldspar and aluminosilicate up to a very high
shear strain (γ = 15). The deformed product is characterized by generation of significant amount of melt and solid residue of
quartz and muscovite. On the other hand, at 800°C and strain rate 3x10 -3 s -1 , the disequilibrium reaction started and produced
K-feldapar and oriented fibers of Sillimanite at a finite shear strain of γ = 2.
1.3
The Triassic detrital units in southern Turkey: synrift or syncollisional
series?
Moix Patrice*, Champod Eric* & Stampfli Gérard M.*
* Institut de Géologie et de Paléontologie, Anthropole, Université de Lausanne, CH-1015 Lausanne (Patrice.Moix@unil.ch)
Turkey is composed of several terranes separated by complex suture zones. The present day juxtaposition results of large
lateral displacements and north/south shortening from the Variscan to the Alpine cycles (Moix et al., 2008). The first amalgamation
was realised during the Late Carboniferous Variscan orogeny (closure of the Rheic Ocean and opening of the
Paleotethys). At this time, several terranes were detached from Gondwana and collided with the southern margin of Eurasia,
e.g. Pelagonia, Anatolian Terrane, Sakarya. Then, the second amalgamation took place during the Late Triassic with the closure
of the Paleotethys and the concomitant opening of the Neotethys along the Gondwana northern margin. Meanwhile,
the southward retreat of the Paleotethyan slab caused the collapse of the Variscan Cordillera and the opening of back-arc
basins along the southern margin of Eurasia (e.g. Maliac, Pindos oceans). The closure of the Paleotethys (Cimmerian Event)
between the Taurus and the Anatolian terranes produced at places large flysch-molasse deposits often sealed by Liassic platforms.
Finally, the last amalgamation corresponds to the Alpine cycle and is marked by a quasi-synchronous obduction of
SSZ-type ophiolites during the Late Cretaceous.
For a long time, the idea of a Dinarides-Hellenides-Taurides-Zagrides continuum has been discussed. The Southern Aegean
Islands in Greece form an important landmark between the Hellenic-Dinaric system to the west, and the Anatolian-Tauric
one to the east. The most external parts of the Hellenides-Taurides system present striking similarities (e.g. Bernoulli et al.,
1974). In particular, the platform development of the Beydağları/Susuz Dağ para-autochthonous sequence in Turkey correlates
well with the pre-Apulian units of the Paxos-Zanthe-Kastellórizo zone in Greece. The study of ophiolites related to these
units and their associated mélanges is a key point for any correlations (e.g. Koepke et al., 2002). K-Ar dating of SSZ-ophiolitic
remnants found in Rhodes and Karpathos yielded an early Late Cretaceous age around 90 Ma. These ophiolites show more
similarities with the south Turkish ophiolites than with the Hellenic-Dinaric ones (Vardar-type ophiolites). On the contrary,
the ophiolites of Crete were dated around 160 Ma and can be therefore correlated with the Hellenic-Dinaric system. The
analysis of the Triassic detritic units in southern Turkey can provide new clues to decipher the complex geodynamic history
of the East-Mediterranean realm. The sandstones, breccias and conglomerates usually range from the Anisian (Scythian?) to
the Late Triassic (sometimes Liassic) and are especially well-developed during the Upper Triassic interval. They are found both
in para-autochthonous, i.e. Gondwana-derived Taurus terrane and in allochthonous positions, i.e. Anatolian-derived nappes.
(1) The detritic units belonging to the para-autochthonous series are often interstratified in platform-type developments
ranging locally from the Cambrian to the Tertiary. Elements from these flysch-molasse deposits have yielded Upper
Carboniferous-Lower Permian pelagic radiolarian cherts, Upper Pennsylvanian Ural-type Fusulinids, Permian pelagic conodonts,
Lower, Middle and Upper Permian Fusulinids, Permian and Triassic smaller foraminifers, Lower Triassic pelagic conodonts
plus various granites, gneiss, micaschists, quartzites and sandstones. These detritic units may be correlated with the
Shemshak Formation in the Alborz in Iran and with the base of the Tripolitza Unit known as the Ravdoucha-Tyros beds in
Greece. The latter consist of conglomerates, sandstones and violet slates. The elements are polygenic and composed of limestones,
sandstones and lydites ranging from Carboniferous to Norian. All these sequences are interpreted as the Eocimmerian
flysch-molasse sediments, probably deposited in a foreland basin during a syn- to post-collisional stage between Gondwanan
and Eurasian-derived terranes.
(2) The detritic units belonging to the allochthonous series are often associated with volcanism. They are generally situated
at the base of sequences showing shallow-water sedimentation passing up to pelagic conditions and finishing with flysch/
wildflysch deposits. The Köyceğiz series in the Lycian Nappes presents a typical succession of the Pindos Unit (Upper Triassic-
Liassic Gereme platform, Liassic-Cenomanian Çal Dağ pelagic limestone, Turonian Çamova flysch and Late Cretaceous
Karabörtlen wildflysch). To the west, these series have their equivalent in Rhodes, Tilos, and Karpathos. In the External