Genesis of ferromanganese crusts in Jurassic pelagic limestones at Stankowa Skała, Pieniny Klippen Belt, Poland: sedimentological and petrological approach

Abstract

The ferromanganese crusts (FMC) and nodules at Stankowa Skała near Nowy Targ (Pieniny Klippen Belt, Poland) are developed in pelagic condensed limestones. The crusts appear on an uneven surface of limestones with thinshelled [i]Bositra [/i]bivalves dated to the (?)uppermost Bajocian -Callovian. The crusts are overlain by Oxfordian limestones rich in [i]Globuligerina[/i], containing Fe-Mn nodules and small fragments of calcite stromatolites rich in Mn, Fe, Ba oxyhydroxides. Petrological analyses of the FMC from Stankowa Skała indicate their hydrogenetic origin. Growth of the FMC was coeval with a period of a rapid oceanic floor spreading from the Bajocian to the Callovian, postulated for the Pieniny Klippen Belt in the Jurassic time on the basis of the palaeomagnetic studies.