The giant quaternary Ballik travertine system in the Denizli basin (SW Turkey): a palaeoenvironmental analysis

Abstract

This research forms the basis for the applicability of the Dunham (1962) classification of carbonated rock lithofacies to the analysis of the giant Ballik travertine architecture, while reconstructing lateral and vertical environmental changes. This study provides an analogue for spring-related deposits encountered offshore Brazil and Angola by linking macroscopically travertine lithofacies distribution to depositional environments. The analysis is based on rock-building constituents such as gastropods, charophytes, intraclasts, phytoclasts, coated grains, dendrites etc., forming micro-sedimentary fabrics with different structures such as packstone, grainstone, wackestone and boundstone, these latter closely associated with crust of dendrites and phytoherm of reeds and bryophytes. Our findings indicate that the Ballik travertine area consists of a “Lower” and an “Upper Domain” reflecting different depositional environments. More specifically, the “Lower Domain” consists from west to east of a laterally complex amalgamation of extended pool, marsh pool and flood plain environments that formed from a mixture of spring and ground waters. The extended pond environment characterised by a boundstone facies of stromatolites in the west evolves eastward into a marsh pool and flood plain. This is because CO2 degassing and water temperature decreased as the water depth of the Lower Domain reduced towards the east. The marsh pool environment includes packstone to grainstone lithofacies and abundant wackestone lithofacies made of phytoclasts, whose crusts exhibit pustular fabrics. Moreover, the flood plains along with the marsh pool consist dominantly of packstone to grainstone lithofacies with many gastropods and intraclasts, interfingered with wackestone lithofacies made of phytoclasts. Irregular clotted fabrics, along with coated grains with radial fibres, high lime mud content with bioturbation are also present. The “Upper Domain” displays a laterally less heterogeneous palaeoenvironmental distribution with flooded slope and flood plain deposits. The eastern part of the “Upper Domain” is characterized by a systematic alternation of these environments, with intercalations of wackstone lithofacies made of phytoclasts, packstone to grainstone lithofacies made of intraclasts and lime muds as well as coated grains. The flood plain has coated grains having peloidal nuclei and coatings of sparry laminations and clotted fabric of peloids representing intraclasts, whereas, the flooded slope possesses coated grains with coatings of dendrites and nuclei of peloids, boundstone of stromatolites which have flat‑laminated and columnar-laminated fabrics indicating a laminar discharge away from the spring(s). Alluvial fan and palustrine deposits with abundant bryophytes and reeds frequently interfinger with marsh pool environment in the “Lower Domain”, and with the flood plain and flooded slope environments in the “Upper Domain”. The results illustrate well how environmental changes identified in the two different domains have induced heterogeneity in reservoir‑based depositional architecture.