Early and Mid-Cretaceous Buildups
Published:January 01, 2002
Early Cretaceous carbonate platforms were widespread and thick, and complex biotic associations formed reefs that contributed significant amounts of carbonate sediment. An analysis of three time slices, late Tithonian to early Valanginian, late Valanginian to early Aptian, and late Aptian to mid-Cenomanian, shows that although carbonate platform development increased throughout this span, it was stressed during the mid-Valanginian, the mid-Aptian, and the latest Cenomanian. These stress periods were also times when shallow-water rudists and calcareous algae experienced significant decline in abundance and diversity. These times of extinction were followed by diversification of new forms. The drivers of these stress events were a complex chain of events from increased rates of ocean-floor spreading, oceanic volcanism, increased and/or expanded anoxia within the ocean water column, increased nutrients and marine plankton productivity, and deposition of organic matter.
During the Early Cretaceous, carbonate platform ecosystems comprised a deeper-water association of mainly siliceous sponges, stromatolites, and some types of scleractinians and a shallow-water association of corals and rudists that built reefs and other structures. During the Aptian-Albian, intraplatform basins developed and their ramp margins generally were occupied by rudist-dominated associations of increasing biotic diversity.
Figures & Tables
Phanerozoic Reef Patterns
Detecting patterns and processes of ecosystem evolution is among the main challenges of an integrated earth system science in the 21st century. The evolution of reefs reflects changes triggered by evolutionary innovations and variations in global and regional controls at different scales. The prime fossil record of Phanerozoic reefs offers the opportunity to trace these patterns through space and time. Phanerozoic Reef Patterns presents a comprehensive and up-to-date review on the history of reef building in the last 540 million years. A selection of internationally respected reef specialists presents a database on ancient reefs that is hardly available for any other ecosystem. The thoroughly documented patterns are analyzed with respect to global change, whose impact on living reefs is intensely discussed today. Phanerozoic Reef Patterns stands out from recent reviews on reef evolution by its careful qualitative and quantitative approach based on a comprehensive and multifaceted databank, by the strong focus on data, by a complete and unified coverage of the Phanerozoic from the Early Cambrian to the late Neogene, by emphasizing paleogeographic reef distributions presented on 32 newly developed color maps, and by a detailed index that makes the book a valuable research tool.