THE CENOMANIAN-TURONIAN TRANSGRESSION IN THE IBERIAN RANGES (SPAIN) - DEPOSITIONAL SEQUENCES AND THE LOCATION OF THE CENOMANIAN-TURONIAN BOUNDARY

In the central Iberian Ranges the Cenomanian-Turonian boundary is located within a 3rd-order depositional sequence. Sedimentation began following an Atlantic transgression which flooded the Iberian plate from its northern margin. Facies are deepest, mainly hemipelagic, in the north (marls and nodular limestones with ammonites, echinids and pelecypods) and shallower, shelf and coastal, in the south (dolostones, detrital limestones, rudist-bearing limestones, etc.). The main feature of the sequence was a northwards propagation of the neritic over the hemipelagic facies. The succession is composed of five 4th-order parasequences. The lower two are interpreted as Transgressive Systems Tracts, whereas the others are interpreted as Highstand Systems Tracts. The age of the sequence is Late Cenomanian (parasequence 1) and Early Turonian (2 to 5). The Cenomanian-Turonian boundary then is not coincident with the limit of a major depositional sequence. © 1993 Academic Press. All rights reserved.