Publikacje

Abstract:

The Middle Ordovician (Dapingian) of the northern Holy Cross Mountains (central Poland) is represented by condensed limestones that make up the Pobroszyn Formation. They reveal a complex stratification reflecting alternating depostional conditions. The basal lime-stones were deposited in open-marine conditions during the early Middle Ordovician sea level rise (navis Zone) correlated with the Baltoscandian Gardlosa drowning. Periods of non-deposition associated with this transgression favoured precipitation of authigenic Fe Minerals close to the sediment-water interface. The upper part of this succession appears to represent a succeeding depostional phase associated with a second transgressive event, which probably involved reworking of the underlying lithlified substrate. High energy events were interrupted by periods of non-deposition favouring development of benthic microbial communities contributing to Fe authigenesis. The Pobroszyn Formation reveals features suggesting an early diagenetic alteration of the parent carbonate sediment in a shallow marine setting (e.g.. beach shoreface) or even was influenced by meteoric diagenesis, which probably took place during a sea level fall preceding the second transgressive event.

POWRÓT

Strona główna > Publikacje

Sedimentary and diagenetic environments of Middle Ordovician iron-rich limestones (Pobroszyn Formation) in the northern Holy Cross Mountains, Poland