Bored surfaces in Middle Jurassic limestones in northeastern France indicate syn-sedimentary lithification. The sedimentary structures and textures, and age relationships between the bored carbonates and the argillaceous sediments above them suggest that the lithification has occurred in both submarine and intertidal environments. The diagenetic fabrics which have resulted from this early marine lithification include three types of calcite druse, echinoderm overgrowths, and microcrystalline cements. Most of these cements are comparable with those forming today in inter- and subtidal environments of the Persian Gulf.
The localization of bored surfaces (“hard grounds”) at the tops of regressive carbonate sequences is interpreted as being the result of slow carbonate sedimentation and lithification of the Jurassic sea-floor prior to the onset of argillaceous colder, or deeper-water sedimentation.