Patterns and Processes of Ancient Reef Crises

Abstract

Reef crises need to be separated from mass extinctions because they are manifested in reductions of reefal carbonate production rather than elevated extinction rates. The volume of preserved fossil reefs per unit time is perhaps the best accessible metric to assess reefal carbonate production rates in the geologic record. Although this metric is prone to biases introduced by weathering, burial, and sampling, it offers the possibility to analyze general connections between reef crises and mass extinctions. The biases can be partially corrected by looking at short-term variations and by utilizing independent proxies of sampling. Using a comprehensive database of ancient reefs and considering the generally high volatility in reefal carbonate production, we can identify five significant metazoan reef crises in the post-Cambrian Phanerozoic, only three of which correspond to traditional mass extinctions. Ancient reefs crises appear to be due to episodes of rapid CO2release and warming, rather than cooling or meteorite impacts.