“Time-Specific Facies” and biological crises — The Kellwasser Event interval near the Frasnian/Famennian boundary (Late Devonian)

Features which may be called “Time-Specific Facies” (TSF) can be linked to global bioevents — or better biological crises. The Late Devonian Kellwasser (KW) Event is a classic example of such a crisis. This geologically short-lived “event” shows recurring patterns within the critical time interval, including patterns that are often minute. Not only do the well-known Lower and Upper KW Horizons yield specific features, but also the adjacent sedimentary rocks show characteristic markers. Such observations were first made in facies settings of submarine rises with preferably carbonate rocks (mainly cephalopod limestones), but these features can now also be traced into basinal sections characterized by fine-grained pelitic rocks. These beds and markers are crossing traditional facies borders at exactly the same time, making them perfect examples of TSF.