Annales Societatis Geologorum Poloniae (2005), vol. 75: 155-169. FACIES AND SEDIMENTARY ENVIRONMENTS OF THE UPPER SCYTHIAN-CARNIAN SUCCESSION FROM THE BELANSKE TATRY MTS., SLOVAKIA Tomasz RYCHLIŃSKI & Joachim SZULC Institute o f Geological Sciences, Jagiellonian University, Oleandry 2a, 30-063 Krakow, Poland; e-mail: [email protected], [email protected] Rychliński, T. & Szulc, J., 2005. Facies and sedimentary environments of the Upper Scythian-Camian succession from the Belanske Tatry Mts., Slovakia. Annales Societatis Geologorum Poloniae, 155-169. Abstract: The Triassic Fatricum basin studied in the Belanske Tatry Mts. (Slovakia) was a relatively stable and restricted platform area influenced by eustatic and climatic fluctuations. During the early Triassic the platform was influenced by continental clastic sedimentation intermittent with shallow marine transgressions when carbonate sediments formed. Common occurrence of carbonized plat debris suggests relatively humid climatic conditions dominating during this interval (Werfenian facies). Significant climate aridisation was concurrent with the beginning of the Middle Triassic transgression as indicated by evaporitic fabrics common within the entire Middle Triassic carbonate succession. The Middle Triassic has been divided into several lithofacies complexes reflecting the interplays between the eustatic and climatic fluctuations. The lower Middle Triassic complex (lower-middle Anisian?) displays dominance of calcareous sediments indicating free communication with the open ocean. The subsequent intervals are rather uniform facies assemblage composed by dolomites and evaporites formed in a restricted and stagnant basin. The basin has been strongly influenced by subtropical storms, particularly common in the late Anisian. Transgression pulse in the early Ladinian involved growth of microbial colonies building thrombolitic biostromes. Final shallowing by the end of Ladinian led to replacement of carbonate sediments by continental clastics of the Carpathian Keuper. These sediments, mostly of alluvial nature, comprise plant debris what suggests climate pluvialisation in Carnian times. Key words: facies, paleoenvironments, late Scythian-Carnian, Belanske Tatry Mts. Manuscript received 27 July 2004, accepted 30 June 2005 INTRODUCTION the upper Lower Triassic to lower Upper Triassic (“Carpa­ thian Keuper”). This succession corresponds approximately The Triassic rocks of the Belanske Tatry Mts. (Slova­ to the late Scythian-Carnian interval. The inferring recon­ kia; Fig.1), represent sediments formed within the Fatricum struction of the basin evolution should give rise for future basin. These sediments are recently incorporated into the refining of chronostratigraphic resolution by means of se­ Krfzna Nappe (Fig. 2). Triassic sedimentary facies, evolu­ quence stratigraphy. tion of the basin and its controls are poorly recognized as­ pects of the basin history. The only exception is the Rhae- tian where detailed paleontological and facies studies have GOALS AND METHODS been done (Gaździcki, 1974; Gaździcki et al., 1979). The section of the Belanske Tatry Mts. comprises some 100 m A composite measured section has been done for the thick profile of the late Scythian and less than 400 m thick study area. Particular sedimentological field works (Rych­ succession of the Middle Triassic. Definite thickness of the liński, 2001) encompassed southern slopes of the Hlupy Carnian succession is uncertain but exceeds 50 m. (Szalony Wierch; Fig. 3) and Zdiarska Vidla Mt. (Płaczliwa Scarcity of index fossils hinders precise stratigraphic Skała), belonging to the Havran unit. The sedimentological division of the succession. The only attempt of stratigraphi- study have been supplemented by the microfacies and stable cal division was done by Kotański (1958) who divided the isotopes examination. The values of S13C and S18O were Middle Triassic into the Anisian stage that comprises dado- measured with the mass spectrometre SUMY, at the Insti­ crinids and the Ladinian stage with Encrinus sp. tute of Geological Sciences, National Academy of Sciences The present paper focuses on sedimentological charac­ of Belarus at Minsk. The samples were treated with 100% teristics and facies analysis of the Triassic succession from orthophosphoric acid, next carbon dioxide was collected in 156 T. RYCHLIŃSKI & J. SZULC Wierchowa unit (so called autochthonous series) lying di­ rectly on the crystalline basement, built of Paleozoic igne­ ous and metamorphic rocks. The second one is composed of several nappes, which represent Tethys palinspastic units (Haas et al., 1995; Rakus et al., 1998) and cover the auto­ chthonous series. In the Tatra Mts. have been distinguished: the lowermost - KriZna Nappe which represents palinspas­ tic Fatricum unit, the middle - Choc Nappe that corresponds to the Hronicum, and the uppermost - StraZov Nappe (as suggest Kotański, 1979) that corresponds to the Silicicum. The described section belongs to the KriZna Nappe. The basic geological and tectonic outline of the Belanske Tatra Mts. has been presented by Andrusov (1936, 1959) and by Sokołowski (1948). Their tectonic observations has been re­ Fig. 1. The location of the studied section cently completed by Lefeld (1999). According to Lefeld (1999) the KriZna unit in the Belanske Tatry Mts. has been divided into three tectonic units. The lower one, Subtatric a trap with liquid nitrogen and purified in vacuum. An error partial nappe, corresponds to the Suchy Wierch unit of the of measurement was about ±0.2%o . In the paper all the stable Zakopane Subtatric area and is better exposed in the western isotopes ratios in carbonate samples are presented with ref­ part of the Belanske Tatry Mts. The middle one - the erence to the PDB standard. Havran partial nappe (Sokołowski, 1948) - builds the south­ Because of the poor knowledge about sedimentary en­ ern slopes and main ridge of the Belanske Tatry Mts., vironments of the middle Triassic from the Havran unit the whereas the higher one - the Bujaci (Bujaczy) partial nappe main goal of our paper is reconstruction of the sedimentary - builds the northern slopes. The petrographical study of the environments and basin conditions as well as theirs influ­ Belanske Tatry Mts. done by Borza (1958, 1959) concerned ences on the facies development during late Scythian-Car­ mainly the continental clastics of the Lower and Upper Tri- nian times. Finally we compare the Fatricum basin with assic and younger sediments. Some microfacies data for the other Triassic basins from the Western Tethys domain. Triassic carbonates of the Havran partial nappe have been discussed by Misik (1972). We use the stratigraphical nomenclature for Triassic of GEOLOGICAL SETTING the Belanske Tatry Mts introduced by Mello and Wieczorek AND STRATIGRAPHICAL UNITS (1993a) and Michalik (1997a). The oldest Triassic sedi­ ments of the studied area are quartzite sandstones, which Sedimentary series in the Tatra Mts. represent generally have been defined as LuZna Formation. According to two different types of tectonic components. The first one - Sokołowski (1948) and Kotański (1958) it belongs to Sei- Fig. 2. Geological sketch of the study area (after Michalik et al., 1997, simplified) UPPER SCYTHIAN-CARNIAN SUCCESSION, TATRA MTS. 157 Fig. 3. View of the Middle Triassic section of the Hlupy Mt. Arrow indicates karst site presented in Fig. 12A, B sian of the Havran Unit, but it may be a part of the lower­ tion the pseudomorphs disappear and the carbonates be­ most tectonical units as proposed by Lefeld (1999). How­ come coarser-grained. Kotański (1958) called these sedi­ ever the latter suggested also, that within the Havran - Jah- ments as “Myophoria beds” and ascribed them to the naci (Jagnięcy) elevation only the Havran unit is more or Campilian, that is to the late Scythian. Thickness of the less preserved (cf. Fig. 2). The overlying mixed clastic- Lower Triassic series reaches ca. 80 m. carbonates sediments with rauhwackes belong to Sunava Formation. In the Polish Tatra Mts. the rauhwacke carbon­ Middle Triassic ates have been described as informal Myophoria beds (Ko- tański, 1963). The Middle Triassic carbonates have been di­ Scarcity of fossils, in particular the index ones, makes vided into Gutenstein Formation (including dolomites and the stratigraphic resolution of the Middle Triassic very limestones of Anisian age) and Ramsau Formation that in­ vague. The only fossils of stratigraphic significance are rare cludes light grey dolomites of the Upper Anisian-Ladinian crinoids reported by Kotański (1958). Considering however (and Carnian?) age (Plasienka et al., 1997). The Upper Tri- modern taxonomy of crinoids, this determination seems to assic of the study area called Carpathian Keuper (Carnian be uncertain. The above discussed, recently introduced for­ and Norian) is dominated by shales and sandstones with in­ mal units (Mello & Wieczorek, 1993a; Michalik, 1997a) are tercalations of dolomites. The uppermost Triassic (Fatra lacking precisely defined boundaries. Therefore we have Formation - Michalik & Jendrejakova, 1978) is built mainly tentatively divided the Middle Triassic succession into sedi­ of limestones with benthic fauna (Gaździcki, 1971, 1974). mentary complexes after their outstanding sedimentary fea­ tures, which reflect most pronounced changes in sedimen­ tary environments during the Middle Triassic. The supposed DESCRIPTION OF THE SECTION age is ascribed after the mentioned crinoids and by way of comparing of the section