Microencruster-microbial-cement framework of the Upper Jurassic reef developed on the slope of the intra-Tethyan carbonate platform (Bulgaria)

摘要: Abstract The carbonate succession in the Lyalintsi section of western Moesian Platform (western Bulgaria) displays a shallowing-upward trend. Growth Tithonian–Valanginian coral biostromes and low-relief bioherms was preceded by Oxfordian–Kimmeridgian sedimentation fine-grained peloidal-bioclastic limestones Saccocoma-bearing on homoclinal ramp platform slope. In late Kimmeridgian, boundstones with very rare corals, but easily recognisable biohermal morphology, were developed. main components this reef are encrusting microorganisms, microbial crusts synsedimentary cements. Microencrusters Labes atramentosa, Crescentiella morronensis, Perturbatacrusta leini Radiomura cautica, as well thin calcified sponges (sclerosponges), biotic components. Corals (almost exclusively microsolenids) sparse, whereas photophilic microencrusters (e.g., “Lithocodium–Bacinella”), absent, although they common overlying shallow-water part sequence. Microbialites cements provided additional support for framework. framework, especially components, reefal facies position within sedimentary succession, implies that high-energy upper slope depositional setting microencruster-microbial-cement studied. Encrusting except C. morronensis sponges, only known from intra-Tethyan platforms. This study supports conclusion studies coeval Alpine reefs presence framework provides insight into palaeobathymetry, palaeogeography tectonic configuration