Climatic controls on sedimentary environments in the Triassic of the Transdanubian Range (Western Hungary)

During the Triassic the Transdanubian Range was a segment of the western Neotethys margin where the climate was mostly determined by a strong global monsoonal system. As a consequence of the global climatic conditions and its geographic setting, warm to hot temperature prevailed in this area. However, there were significant changes in the precipitation pattern from dry to wet conditions in connection with the intensity of the monsoon system and the actual setting of this area within the monsoon system. The aim of our research was to interpret the palaeoclimatic conditions and their changes for the Triassic succession of the Transdanubian Range on the base of geochemical, mineralogical, sedimentological and palaeontological data, with special regard to the climate indicator facies (e.g. different types of dolomites; clay mineral assemblages). Nine evolutionary stages were distinguished. During the Early Triassic mixed siliciclastic–carbonate ramp sedimentation took place under arid climate that was interrupted by a humid pulse (Campil Pluvial Event). In the early Anisian a shallow carbonate ramp was developed under arid to semi-arid climate. The predominatly dry conditions prolonged during the middle Anisian,. The latest Anisian and the Ladinian carbonate platforms were developed under mostly semi-arid climate. The semi-humid climate of the earliest Carnian was followed by a definitely wet interval (Carnian Pluvial Event) that was characterised by an intense terrigenous input into the Julian intraplatform basins. Arid and humid conditions alternated during the final stage of basin upfilling from the latest Julian to early Tuvalian. Then a marked climatic change took place in the latest Carnian when the humid climate was changed to semi-arid conditions. From the middle to late Norian a gradual increase of humidity may have taken place that resulted in a decreasing intensity of the early dolomitisation of the carbonate sediments of the broad internal platform. At the very end of the Norian there was a marked climate change leading to enhanced humidity but with a definite seasonality. Humid climatic conditions prevailed during the Rhaetian (Kössen Event). tion of the similarities and differences of the palaeoclimatic conditions for the Transdanubian Range and some selected areas in the western Neotethys (Dolomites, Northern Calcareous Alps, Mecsek), and the Peri-Tethyan Germanic Basin is also presented.