Bioerosional structures and pseudoborings from Late Jurassic and Late Cretaceous-Paleocene shallow-water carbonates (Northern Calcareous Alps, Austria and SE France) with special reference to cryptobiotic foraminifera

Examples of bioerosional processes (boringpatterns) are described from shallow-water limestones of the Late Jurassic Plassen Carbonate Platform (PCP) and theLate Cretaceous to Paleocene Gosau Group of the NorthernCalcareous Alps, Austria. Some micro-/macro-borings canbe related to distinct ichnotaxa, others are classied in opennomenclature. In the Alpine Late Jurassic, bioerosional structures recorded from clasts in mass-fows allow palaeo-geographical conclusions concerning the source areas. Inparticular, these are borings of the Trypanites-ichnofaciesdetected from clasts (Barmstein limestones) of the PCP orspecial type of bored ooids of unknown source areas orrestricted autochthonous occurrences. In the Lower Gosau Subgroup, Gastrochaenolites macroborings occur in mobile carbonate clast substrates of shore zone deposits(“Untersberg Marmor”). Different types of borings arerecorded from rudist shells and coral skeleton, some of which are referable to the ichnotaxon Entobia produced byendolithic sponges. In the present study, special attention ispaid to the occurrences of the cryptobiotic foraminifera Troglotella incrustans Wernli and Fookes in the Late Jurassic and Tauchella endolithica Cherchi and Schroeder in theLate Cretaceous. The latter is so far only known to be fromthe Early Cenomanian of France and is reported here for the first time from the Late Turonian-Early Coniacian strati-graphic interval where it was found in turbulent carbonatedeposits within borings penetrating bivalve shells or coral-line algae. The records of cryptobiotic foraminifera fromthe Northern Calcareous Alps are supplemented by a single finding from the Middle Cenomanian of SE France. A palaeoenvironmental interpretation of the occurrences of the cryptobiotic foraminifera is provided.