DEPOSITIONAL ENVIRONMENTS, FACIES AND DIAGENESIS OF THE UPPER JURASSIC–LOWER CRETACEOUS CARBONATE DEPOSITS OF THE BUILA-VNTURARIA MASSIF, SOUTHERN CARPATHIANS (ROMANIA)

摘要

The Buila-Vanturaria Massif consists of massive Upper Jurassic reef limestones (Kimmeridgian–Tithonian) and Lower Cretaceous (Berriasian–Valanginian, and Barremian–Lower Aptian) deposits. Besides corals and stromatoporoids, a wide range of micro-encrusters and microbialites has contributed to their development. In this study, the authors describe briefly and interpret the main facies associations and present the microfossil assemblages that are important for age determination. The distribution of facies associations, corroborated with the micropalaeontological content and early diagenetic features, indicate different depositional environments. The carbonate successions show the evolution of the Late Jurassic–Early Cretaceous depositional environments from slope and reef-front to internal-platform sedimentary settings, including peritidal environments in the lowermost Cretaceous. Early diagenesis, represented by synsedimentary cementation in the form of micritization (including cement crusts in the reef microframework), followed by dissolution, cementation and dolomitization in a meteoric regime, and void-filling late cementation during the burial stage.