Small-scale cyclic sedimentation in the Early Givetian of the Góry Świętokrzyskie Mountains: comparison with the Ardene sequence

Alain Preat, Grzegorz Racki

Abstract


Małoskalowa cykliczna sedymentacja we wczesnym żywecie Gór Świętokrzyskich: porównanie z sekwencją Ardenów

In the section of the Lower Givetian limestones exposed in the Jurkowice-Budy quarry (eastern Góry Świętokrzyskie) 6 shallowing-upward small-scale cycles (thickness ranging from 0.5 to 3.3 nr, average 1.5 in) are identified. Each cycle consists of a subtidal to lower-intertidal muddy unit overlain by an upper-intertidal to supratidal unit with extensive dia- genetic overprint, recording progradation processes. Non-erosive discontinuities separate successive conformable cycles. Distinguishing autocyclic from allocyclic processes is ambiguous in the lagoonal-peritidal sequence. Likely, the sedimentation was primarily controlled by local subsidence, pulses of which were counterbalanced by algal production. Climatically induced (in the frame of the Milankovitch cycles), very low-amplitude sea-level oscillations (less than 2 meters?) and short lag times (between 1000 yr and 5000 yr?) during deepening at the base of each cycle might also contributed to the sedimentary record.

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