Sedimentary facies and depositional environments of the Upper Triassic carbonate-evaporite succession in the Honaz Mountain Range (SW Anatolia, Turkey)

The Upper Triassic carbonate-evaporite-bearing succession in the Honaz Mountain Range (HMR) in SW Anatolia (Turkey), exists as a tectonic slice within the carbonate and ophiolithic units of allochthonous Lycian Nappe stacks. It comprises interbedded layers of sulphates (gypsum) and limestones or dolostones. Sedimentological and palynofacies analyses suggest that the Honaz succession was deposited in the more protected areas of the peritidal zone of a shallow inner ramp under a tropical/arid climate. Three main subenvironments are identified based on facies and microfacies associations: (i) Sabkha, exhibiting two distinct microfacies-gypsum and peloidal packstone/grainstone, (ii) Tidal flat, consisting of six microfacies-cryptalgal boundstone, fenestral bindstone, laminated peloidal mudstone, laminated algal/microbial boundstone, pisolite rudstone, and carbonate breccias, (iii) Lagoon, featuring five microfacies-laminated peloidal packstone/grainstone, crinoidal wackestone/packstone, mudstone, bioclastic packstone, and ostracodal/peloidal packstone to grainstone. The succession is characterized by meter/submeter-scale cyclic facies alternations, similar to Lofer cycles, Dolomia Principale/Hauptdolomit Formation, and Dachstein Formation of European basins.

Facies and petrographic analyses, along with Sr isotope ratios of dolomites, indicate early dolomitization from evaporated seawater in this environment (shallow seepage reflux or evaporative-drawdown). However, the depletion in δ¹⁸O (-11.53 to -5.46 ‰, mean -8.29 ‰), and slightly radiogenic Sr isotope values of dolomites are attributed to a recrystallization process, occurring at high temperatures during burial diagenesis. The relatively high δ¹³C values (+0.76 to +3.60 ‰, mean +2.42 ‰) suggest dolomite alteration in a relatively closed system. The microfacies of the Honaz succession are comparable to those in other Upper Triassic successions (e.g., western Carpathians, Italian Apennines, Spain, northern Calcareous and southern Alps, external Dinarides and Hellenides, southwestern Germanic Basin, Morocco, Israel, Albany) deposited under similar environmental conditions. Comparing facies with those from other coeval sequences allows us to delineate such carbonate-evaporite shallow water platforms on the northern margin of the Neotethys Ocean. This study was supported by the Pamukkale University BAP Research Project (2022ÜBBİD001).