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Kimmeridgian - Tithonian of the pelagic Fatric succession in the Western Tatra (Central West Carpathians, Poland): Integrated bio-, magneto- and chemostratigraphy of the Dolina Lejowa section
Jacek Grabowski, Jolanta Iwanczuk, Renata Jach, Daniela Reháková, Andrzej Chmielewski

Building: Muséum d'Histoire Naturelle de Genève
Room: Lobby /Hall/
Date: 2018-12-05 12:00 PM – 12:03 PM
Last modified: 2018-11-29

Abstract


Kimmeridgian – Tithonian pelagic succession in the  Fatric (Krizna) unit of Western Tatra Mts, ca. 47 m in thickness, comprise uppermost part of radiolarian limestones (Czajakowa Radiolarite Formation), red platy and nodular limestones of Ammonitico rosso type (Czorsztyn Limestone Formation)  and grey marly limestones of the Jasenina Formation. Integrated dating of the Lejowa section (in progress) is based on calcareous dinocysts, calpionellids and magnetic stratigraphy. The interval studied spreads from the Upper Kimmeridgian (Moluccana Zone) to Upper Tithonian (Crassicollaria Zone). According to preliminary magnetostratigraphic interpretation it corresponds to polarity zones from M24r to lower part of M19n.  The Kimmeridgian/Tithonian boundary (Borzai/Pulla zonal boundary) falls in the lower part of the Czorsztyn Limestone Formation. The sedimentation of red nodular limestone terminates in the Malmica or Semiradiata Zone of Lower Tithonian.

Bositra, radiolarian-Bositra and Bositra-radiolarian-spiculite microfacies dominate in the radiolarian limestones of Czajakowa Formation. Variegated microfacies with Saccoccoma (Saccoccoma-radiolarian, Saccoccoma-Globochaete, radiolarian-Saccoccoma-Globochaete and Saccoccoma wackeston/packstone) appear as the most important component of  microfacies in the Czorsztyn Formation. Saccocoma microfacies continue higher up into the lower part of Jasenina Formation. In the upper part of this formation  the calpionellids start to occur and they  stepwise dominate over the the saccocomids. The Saccocoma microfacies finally disappear in the polarity chron M19r and combinations of calpionellid – Globochaete – radiolarian microfacies is the most common. The described succession of microfacies is typical for the Tethys ocean and was described from the Carpathian – Balkan area by numerous authors (e.g., Pszczółkowski, 1996; Lakova & Petrova, 2013; Reháková et al., 2011), minor differences are the result of paleogeography.

The carbon isotopic ratio (δ13C) reveals a smooth decrease from ca. 2.5 ‰ in the Upper Kimmeridgian to ca. 1 ‰ in the Upper Tithonian.  The major decrease between 2.5 ‰ and 1.5 ‰ occurs just in the Kimmeridgian/Tithonian boundary interval. Magnetic susceptibility (MS) in the grey coloured Jasenina Formation correlates very well with lithogenic elements and might be regarded as reliable proxy of terrigenous input.  The correlation is not as evident in reddish Czajakowa and Czorsztyn formations due to more complex rock magnetic properties and mineralogical source of MS (co-occurrence of magnetite and hematite). The detailed chemostratigraphic survey has been performed with handheld Olympus XRF device. The data were verified by data obtained in geochemical laboratory. The amount of terrigenous elements is apparently lower in the Upper Kimmeridgian/Lower Tithonian than in the Upper Tithonian.  Large increase of terrigenous input is observed in the polarity zone M20n (Chitinoidella Zone, Jasenina Fm), which might be compared with so called Hlboč event (Reháková, 2000; Grabowski et al., 2013).