OLIGOCENE SEQUENCE STRATIGRAPHY AND BASIN DEVELOPMENT IN THE DANISH NORTH-SEA SECTOR BASED ON LOG INTERPRETATIONS

Five sequences are defined in the Oligocene succession of the Danish N orth Sea sector. Two of the sequences, 4.1a and 4.3, have been identif ied onshore Denmark. Two types of prograding lowstand deposits are rec ognized. Sand-dominated deposits occur proximally, comprising sharp-ba sed forced regressive deposits covered with prograding lowstand deposi ts. Clay-dominated prograding lowstand deposits occur distally in the sequences. The highstand deposits are proximally represented by thick prograding sandy deposits and distally by thin and condensed intervals . The main sediment input direction was from the north and the northea st. A succession of lithofacies, from shallow marine facies dominated by sand to outer shelf facies dominated by clay, is mapped in each of the sequences. An overall southward progradation of the shoreline took place during the Oligocene, interrupted only by minor shoreline retre ats. (C) 1998 Elsevier Science Ltd. AII rights reserved.