Kredowa powierzchnia niedepozycji w okolicach Krakowa (Mydlniki, Zabierzów): rycia, drążenia, stromatolity

Marek Jasionowski


A Cretaceous non-depositional surface in the Kraków Upland (Mydlniki, Zabierzów): burrows, borings, stromatolites

The discontinuity surface between the Santonian and Turonian (or, in places, Jurassic) strata in the Kraków region is of non-depositional submarine origin. This surface provides broad evidence of extensive burrowing followed by glauconitisation and encrustation with phosphatic stromatolites. Evidence for penecontemporaneous submarine exposure of the Jurassic limestones is provided by borings developed on the topmost limestone surface. Stromatolites exhibit a mixed carbonate-apatitic mineralogy idicative on an interplay of two different processes during their formation: 1) trapping and binding of fine detrital material by microbial mats, and 2) precipitation of probably amorphous calcium phosphate within the mat environment. The non-depositional surface originated under pelagic conditions on a submarine rise as a result of sediment winnowing and (or) bypass due to bottom currents or wave action.

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