Bored and encrusted clasts in the Lower Kimmeridgian carbonates at Sobków (SW margin of the Holy Cross Mts., Poland)

Abstract

Drążenia i inkrustacje klastów w węglanowych osadach dolnego kimerydu w sobkowie (SW obrzeżenie Gór Świętokrzyskich) A layer of biomicrite 30 - 40 cm thick with bored and encrusted carbonate clasts occurs in a sequence of shallow marine, carbonate, Lower Kimmeridgian sediments exposed in the quarry Sobków, SW margin of the Holy Cross Mts. The clasts display several generations of borings (by pelecypods and polychetes) and encrustations (by serpulids and oysters). The clasts were subject to repeated phases of burial, exhumation and overturning accompanied by succesive colonization by boring and encrusting organisms. The described clasts are examples of early lithification of carbonates in a shallow epicontinental sea, with temporarily lowered accumulation rate, but without a stratigraphic condensation.