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EN
Middle-Upper Jurassic pelagic carbonates and radiolarites were studied in the Krížna Nappe of the Tatra Mountains (Central Western Carpathians, southern Poland and northern Slovakia). A carbon isotope stra- tigraphy of these deposits was combined with biostratigraphy, based on radiolarians, calcareous dinoflagellates and calpionellids. In the High Tatra and Belianske Tatra Mountains, the Bajocian and part of the Bathonian are represented by a thick succession of spotted limestones and grey nodular limestones, while in the Western Tatra Mountains by relatively thin Bositra-crinoidal limestones. These deposits are referable to a deeper basin and a pelagic carbonate platform, respectively. The various carbonate facies are followed by deep-water biosiliceous facies, namely radiolarites and radiolarian-bearing limestones of Late Bathonian-early Late Kimmeridgian age. These facies pass into Upper Kimmeridgian-Lower Tithonian pelagic carbonates with abundant Saccocoma sp. The bulk-carbonate isotope composition of the carbonate-siliceous deposits shows positive and negative S C excursions and shifts in the Early Bajocian, Late Bajocian, Early Bathonian, Late Bathonian, Late Callovian, Middle Oxfordian and Late Kimmeridgian. Additionally, the S13C curves studied show a pronounced increasing trend in the Callovian and a steadily decreasing trend in the Oxfordian-Early Tithonian. These correlate with the trends known from the Tethyan region. The onset of Late Bathonian radiolarite sedimenlalion is marked by a decreasing trend in S13C. Increased S13C values in the Late Callovian, Middle Oxfordian and Late Kimmeridgian (Moluccana Zone) correspond with enhanced radiolarian production. A significant increase in CaCO3 content is recorded just above the Late Callovian S13C excursion, which coincides with a transition from green to variegated radiolarites.
EN
The "Nad Moreną" section (Triassic–Jurassic boundary interval) in the Tatra Mts. was previously ascribed to the Choč Nappe (Hronicum domain) or to the Križna Nappe (Fatricum domain). Microfacies analysis of the Rhaetian limestones proves that they belong to the Fatra Formation, particularly because of the fossil biota assemblages. This study definitely proves the Križna (Fatricum) provenance of the "Nad Moreną" section and corrects stratigraphy of the Choč Nappe (Hronicum domain) in the Tatra Mts.
PL
Po raz pierwszy opisano enigmatyczną rudę żelaza, która była wydobywana na południowo--zachodnich zboczach Bobrowca w Tatrach Zachodnich w pierwszej połowie XIX wieku. Jej składnikami są hematyt, goethyt i lepidokrokit, występujące w formie spoiwa drobnoziarnistych piaskowców i mułowców dolnego triasu oraz drobnych żył przecinających te skały. Ruda żelaza ma cechy utworu wtórnego. Tworzy ona czapę wietrzenia i żyłki powstałe wskutek tektonicznej remobilizacji w strefie nasunięcia jednostki kriżniańskiej na autochton wierchowy. Pierwotna ruda występowała prawdopodobnie w formie soczewki siarczków żelaza w osadzie mułowcowo-ilastym źle przewietrzanego basenu. Zawartość żelaza w rudzie utlenionej wynosi około 30%. Praca rzuca nowe światło na genezę rud żelaza i warunki facjalne w serii osadowej dolnego triasu Tatr
EN
An enigmatic iron ore which was exploited on the southwest slopes of Bobrowiec in the Western Tatra Mountains at the early XIX century, was described for the first time. It consists mainly ot hematite, goethite, and lepidocrokite cementing fine grained Lower Triassic sandstones and mudstones or forming secondary veinlets. The iron hydroxides and oxide appear as secondary minerals. They form gossan and tectonically remobilization veinlets, resulting from thrusting Kriżna unit against High Tatric autochthon. Primarily iron was probably deposited in the form of thin sulphide lens along with silty-clay sediments in an isolated euxinic basin. The ore contains roughly 30% Fe. New light on the genesis of iron ores and facies within sedimentary series of Lower Triassic in the Tatra is thrown
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