CENOMANIAN-TURONIAN PLATFORM TO BASIN INTEGRATED STRATIGRAPHY IN THE SOUTH PYRENEES (SPAIN)

The deposits registering the geological events that took place in the South Central Pyrenees during Late Cenomanian and Early Turonian times reflect oceanic changes by the modification of their facies and fossil assemblages. In the basin, where pelagic sedimentation was continuous, the Cenomanian-Turonian boundary is characterized by laminated sediments, rich in 13C and lacking keeled planktonic Foraminifera. Only opportunistic species such as whiteinellids, hedbergellids and heterohelicids survived and reflect high biological productivity in the surface waters. On the inner platform, the shallow marine carbonate sedimentation with abundant large benthic Foraminifera, rudists, and other molluscs producing well defined facies tracts during the Cenomanian is brutally interrupted, and covered by earliest Turonian sediments containing only abundant echinoid debris and calcisphaerids. Interruption of carbonate platform sedimentation and subsequent deposition of echinoids recall the impact of artificial eutrophication in modern coral reef environments. © 1993 Academic Press Limited.