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Middle/Upper Devonian brachiopod shell concentrations from the intra-shelf basinal carbonates of the Holy Cross Mountains (central Poland)

Skompski S., Baliński A., Szulczewski M., Zawadzka I.

Acta Geologica Polonica

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2018

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Vol. 68, no. 4

607--633

EN

A huge isolated accumulation, more than 3 m thick and 10 m wide, of densely packed, uncrushed brachiopods has been found in Józefka Quarry within the Middle/Upper Devonian Szydłówek Beds deposited in a relatively deep environment of an intrashelf basin (Kostomłoty facies zone, western Holy Cross Mountains, Poland). The low-diversity assemblage is strongly dominated by the atrypide Desquamatia globosa jozefkae Baliński subsp. nov. and, to a lesser degree, by the rhynchonellide Coeloterorhynchus dillanus (Schmidt, 1941), which constitute 72.8% and 22.1% of the fauna, respectively. Less frequent are specimens representing the genera Hypothyridina, Schizophoria and Phlogoiderynchus. According to the conodont fauna found within the coquina bed, the stratigraphic position of the shell accumulation is close to the Givetian/ Frasnian boundary. The brachiopods are associated with numerous crinoids and less frequent bryozoans, receptaculitids (Palaeozoic problematica), sponges and solitary corals. Although it is difficult to entirely exclude the autochthonous nature of the brachiopod coquina member, its allochthonous origin and redeposition of the brachiopod shells to the deep basin by gravity flows is much more probable. Such conclusion is supported by the following facts: (1) the position of the complex in a succession of deep-marine basinal facies impoverished in oxygen; (2) its lateral thinning-out and composite internal stratification; (3) the lensshaped geometry of the coquina bed in the section perpendicular to the bedding dip; (4) high variability of the sediments preserved within the shells; and (5) the preferred orientation of the shells. The brachiopods mixed with crinoidal debris were probably transported by low-velocity, high-density, gravity-induced debris flows. Lack of fossils typical of the Middle Devonian shallows, such as massive stromatoporoids, amphiporoids and tabulates, indicates that the source area of the bioclastic material was not located in the shallowest part of the shelf, but most probably on a submarine sea-mount to the north of present-day Józefka, as suggested by earlier investigators. The triggering mechanism of the allochthonous deposition was an earthquake rather than storm activity. The enormous thickness of the brachiopod complex is probably caused by the sinking of bioclastic material, transported in succeeding depositional multi-events, in a soft, muddy bottom, typical of the Szydłówek Beds deposition.

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Two hundred years of geological sciences at the University of Warsaw

Szulczewski M.

Acta Geologica Polonica

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2016

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Vol. 66, no. 3

257--260

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Refleksje krytyczne nad austro-węgierskimi reliktami w stratygrafii dolnego triasu w Tatrach

Szulczewski M.

Przegląd Geologiczny

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2010

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Vol. 58, nr 11

1070-1078

EN

The stratigraphic subdivision of the Lower Triassic in the Polish Tatra Mountains is composed solely of units of Alpine origin set in variable configurations. Unification of the stratigraphic classification over a vast area situated between the Dolomites and the Tatra Mountains is partly an effect of its long lasting integration in one state and within the domain of German-speaking geologists. This subdivision has never been soundly applied to the Lower Triassic of the Tatra Mts. on either palaeontological or any other satisfying basis. It has also lost its ground in its type areas, where other stages of extra-European origin has since long been adopted. Hence, the Werfenian, Seisian, Campilian, as well as the Scythian and the Myophoria Beds need to be definitely removed from the stratigraphic nomenclature and replaced with lithostratigraphic subdivision. The lithostratigraphic units should be implemented within their natural limits, therefore the units that have so far been created in the Slovakian part of the Carpathians should be adopted as it is possible.

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Lofer-type cyclothems in the Upper Devonian of the Holy Cross Mts. (central Poland)

Skompski S., Szulczewski M.

Acta Geologica Polonica

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2000

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Vol. 50, no. 4

393-406

EN

Numerous horizons of carbonates changed by karstic and soil-forming processes have been recognised in upper part of the Frasnian carbonate succession in southern part of the Holy Cross Mts. These layers are included in peritidal cyclothems, characterised by mostly deepening upward pattern, similarly to the typical Triassic Lofer cyclothems. The irregular cyclothemic intervals are restricted to an interior part of the isolated, reef- and shoalrimmed Dyminy carbonate platform. The Lofer-type cyclicity correlates with syndepositional block-faulting and associated seismic shock induced features, recognised in marginal parts of the platform. The most appropriate explanation of cyclicity is differentiated, tectonically controlled subsidence of Dyminy platform, according to the stick-slip faulting model proposed by CISNE (1986) for explanation of deepening-upward cyclicity in Dachstein Formation