Organic carbon accumulation events in the mid-Cretaceous rocks of the Pieniny Klippen Belt (Polish Carpathians) -- a petrological and geochemical approach

Patrycja Wójcik-Tabol

Abstract


New petrological and geochemical data lead to a consistent depositional model of the Corg.-rich sedimentation within the Pieniny Basin during the mid-Cretaceous. Considerable terrestrial runoff into the Pieniny Basin occurred during the late Albian. Detrital macerals accumulated under aerobic conditions on the shelf and continental slope. Fertilization of surface water induced primary productivity; aerobic degradation of organic matter led to the development of an oxygen-minimum zone within mid-water. The oxygen-minimum zone spread over almost all of the Pieniny Basin (Albian/Cenomanian). At the same time, a stagnant pool developed in the Grajcarek Basin. During the mid-Cenomanian the O2 minimum zone retracted and covered only the shelf and upper/middle slope. Stagnant pools might have formed in the depressions. Turbidity currents flowed down the slope and deposited calciturbiditic sequences with organic detritus in the Branisko and Pieniny basins. At the end of the Cenomanian, isolated anoxic or even H2S-bearing basins existed on the shelf. The slope was still occupied by the oxygen-minimum zone. In the deepest part of the sea-floor a stagnant basin formed.

Keywords


Pieniny Klippen Belt; mid-Cretaceous; oceanic anoxic events; black shales; geochemical indicators

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