Skały wapienne i wapniste we fliszu polskich Karpat zewnętrznych

Stanisław Leszczyński, Kazimiera Malik

Abstrakt


CARBONATES IN FLYSCH OF THE POLISH OUTER CARPATHIANS

Summary
The Outer Carpathian flysch sequence (U. Tithonian-L. Miocene) consists of deep-water mainly siliciclastic sediments. Carbonates are volumetrically and stratigraphically subordinate. Their abundance is different in particular nappes (Fig. 1) and displays rapid lateral and vertical changes. In all nappes, the Turonian-Paleocene, and uppermost Eocene-L. Miocene sequences are distinctively enriched in calcareous material. An additional carbonate enriched division i.e., the Tithonian-Barremian is recorded in the Silesian nappe sequence comprising sediments of the entire U. Tithonian-L. Miocene time-span. The content of calcareous material in vertical sections displays sometimes distinctive fluctuations at a scale of several decimeters (Fig. 2E) up to several tens of meters. The bulk of calcareous material occurs in calcilutites, marlstones and calcareous mudstones to claystones. These are chiefly resediments (turbidites, debrites etc.), although, pelagites also are represented. Particles of older carbonates (Fig. 2B, D) concentrate in coarse-grained, thick-bedded deposits where the carbonate material is usually subordinate. The amount of synsedimentary particles is inversely proportional to the quantity of the coarse siliciclastic material. The calcareous resediments form very thin to very thick beds (Fig. 2C). Distribution of carbonate material in sequences of the Outer Carpathian flysch was chiefly controlled by tectonic activity of the area, eustasy, climate and biocoenosis. To some extent it was also shaped by basin geometry and autocyclic processes. Tectonic activity that highly varied in time and space together with very irregular basin geometry andautocyclic processes are considered to be responsible paricularly for the lateral facies changes. Influences of eustasy appear to be reflected in some correlation of the carbonate enriched sequences with the global cycle chart, especially of the long term cyclicity. Enhanced sedimentation of calcareous material occurred during the early regressive phase of the sea-level (Fig. 3)~ Eustatsy also influenced carbonate sedimentation through the CCD. This parameter controlled pelagic carbonate sedimentation dependingon the depth of particular basin. Global deepening of the CCD together with rising movements in the Carpathian area, andhigh carbonate productivity resulted in gradual increase of pelagic carbonate material over the Upper Eocene sequence in all nappes (Globigerina Marls = margle globigerynowe). Moreover, episodes of intensive pelagic sedimentation of calcareous nannoplankton occurred in the Late Oligocene (Jasło Limestone = wapienie jasielskie). The smaller vertical fluctuations in carbonate content appear to result from a climate change due to Milankovitch orbital perturbations of the Earth movements (precession and eccentricity).

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