ÇAĞRILI KONUŞMALAR / KEYNOTES Invited Speeches ... - TPJD

Sedimentary Facies and Depositional Environments of the Upper Triassic
Carbonate-Evaporite Succession of Denizli-Kızılyer (SW Anatolia, Turkey)
Hülya Alçiçek 1 Baki Varol 2 Anna Gandin 3
1 Pamukkale University, Department of Geological Engineering, Denizli
2 Ankara University, Department of Geological Engineering, Ankara
3 Siena University, Department of Earth Sciences, Siena, Italy
The Upper Triassic carbonate-evaporite Kızılyer unit, which outcrops mainly in southeastern
Denizli area (SW Turkey), occurs as a tectonic slice within the carbonate and ophiolithic
units of allochthonous Lycian nappes (Alçiçek et al, 2003; Gündoğan et al., 2008). It consists
of interbedded layers of sulphates (anhydrite/gypsum), dolostone and dolomitic limestones
represented by: Lithofacies-I: dark gray homogeneous dolostone, including three microfacies:
mudstone: dolomicrite, with rare ostracods and ghosts of foraminifers; wackestone-packestone:
dolobiomicrosparite, including peloids, foraminifers, rare ostracods and echinoderm plates
with syntaxial overgrowths; and bioclastic packstone: composed of ostracods, ossicles of
echinoderms/crinoids and peloids; and Lithofacies-II: light-dark grey dolomitic limestone with
fenestral fabrics, including two microfacies: cryptalgal boundstone composed of discontinuous
cryptalgal laminae which fragments are separated by dolosparitic or sulphate cements and
ostracod/peloidal packstone-grainstone: made up of alternating layers containing ostracods,
algal aggregates and traces of hyaline foraminifers. Sedimentological and micropalaeontological
evidences indicate that Kızılyer succession was deposited in protected environments of the
peritidal zone of a shallow inner ramp under a tropical/arid climate. Evaporite-associated
dolomites are generally interpreted to be related to brine-seepage-reflux in a broader sabkha
system. During transgressive phases, water exchange between the platform top and the open
sea is enhanced resulting in normal marine to slightly restricted lagoonal water masses and
carbonates precipitated in lagoon environment. With sea level falling, the water exchange with
the open ocean becomes more and more restricted, the salinity of the lagoonal water increases
by evaporation and then sulphates deposited in this environment. The Kızılyer carbonates display
a relatively wide range of δ18O (-8.93 to -5.38‰), whereas δ13C range from +1.76 to +3.26‰.
The low δ18O values, interpreted to be the result of isotopic fractionation due to a thermal
effect indicate the temperatures (40-72°C) of early diagenetic dolomitization. The relatively high
δ13C values suggest that the dolomites experienced alteration in a relatively closed system.
The lithofacies and microfacies of the Kızılyer succession are comparable to those of other
Alpine Upper Triassic successions (i.e. Crete, Apennines, Alps, Carpathians), deposited in similar
peritidal conditions. However, the Kızılyer facies indicate a more restricted position within the
intraplatform due because of the poorly diversified microfauna. It is difficult to interpret the early
diagenetic evolution of the dolostone in this sequence due to their late diagenetic alteration.
The comparison of facies with those from other Mediterranean coeval sequences allows us to
confine the Kızılyer’s sedimentation on the northern margin of the Tethys Ocean.
Keywords : Upper Triassic, Southwestern Turkey, Sedimentology, Evaporites, Peritidal
carbonates
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