Faunal dynamics of bivalves and scaphopods in the Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn, Kraków-Silesia Homocline, Poland

Andrzej Kaim, Przemysław Sztajner


The environment at the Gnaszyn section – as deduced from bivalve and scaphopod dynamics – was controlled by the substrate consistency and possibly oxygen deficiency near the sediment-water interface and/or oxygen content fluctuations. The middle part of the section dominated by nuculoid and corbulid bivalves and Laevidentalium-type scaphopods probably reflects a soupy substrate and possibly oxygen deficiency in the sediment. Slightly coarser and better-oxygenated silts in the upper and lower parts of the section offered a less soupy substrate consistency, allowing the development of communities dominated by astartids, byssate bivalves, and Dentalium- and Plagioglypta-type scaphopods.


Poland; Gnaszyn; Ore-bearing clays; Jurassic; Bathonian; Palaeoecology; Bivalves; Scaphopods.

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