Middle-Upper Jurassic and Lower Cretaceous biostratigraphy and sedimentology of the sub-tatric succession in the Tatra Mts (Western Carpathians)

Abstract

The Middle-Upper Jurassic and Lower Cretaceoos deep-see sequence of the sub-tatric succession of the Tara Mts consists of Toarcian-Aalenian nodular limestones, Bajocian Bathonian radiolarites, Callovian nodular limestones, Oxfordian radiolarites, Kimmeridgian noduaar limestones, Tithonian-Berriesian siliceous limestones (Biancone), and Valanginian-Barremian (Lower Aptian?) marlstones. Two maximal depth phases were observed namely the Middle Jurassic and Qxfordian ones. The carbo-silite sequence of the Upper Jurassic is characterized by distinct vertical symmetry in the distribution of noduIar limestone and radiolaritic facies.
The Middle Jurassic and Oxfordian (the latter in particular) depth phases were of universal character in the Tethyan troughs of the Carpathians and probably of the Alps as well. The dopocenter of these sediments was probably a slope of trough. The deposition depth is considered in relation to calcite and aragonite compensation depths end based on microfacial anaIysis (selective solution). A sequence of calcareous avalanche turbidites (the Murań limestone) of Hauterivian-Barremian age is analysed and its conditions of sedimentation considered. Its origin was due to avalanche and turbidite current transport from distal and possibly also proximal Urgonian reef-detrital zones. On the basis of facial analysis of these redeposited sediments a direct connection of some of the sub-tatric units (Eastern Tatra Mts) with the most southerly situated Klippen Belt succession (Haligovce) is suggested. An Upper Tithonian ammonite fauna was found in the sub-tatric succession. 9 Upper Tithonian ammonite species and genera are described and 8 of them illustrated. The Lower Cretaceous ammonite fauna comprises Valanginian, Hauterivian and Barremia forms, out of which 14 are described and 7 illustrated.