GEOCHEMICAL APPROACH (CARBON ISOTOPES AND IRIDIUM) OF THE CRETACEOUS PALAEOCENE BOUNDARY IN THE OMAN MOUNTAINS - A CATASTROPHIC EVENT IN A GEOCHEMICAL SUCCESSION OF EVENTS FROM THE MAASTRICHTIAN TO THE DANIAN/

In Oman, the sedimentary basins located along the edges of the Oman Mo untain chain show continuous sedimentation at the K/T boundary. Two di stinct sedimentary palaeoenvironments have been analysed. In the north western flank of the Oman Mountains (near Buraymi), the K/T boundary o ccurs within hemipelagic deposits; whereas in the Abet basin (southeas tern flank), it occurs within confined carbonate platform facies. The negative partial derivative(13)C shift and the positive iridium anomal y, which characterize the global geochemical events of the K/T boundar y in marine sections, have been detected in Oman. Moreover this isotop ic signature is nor the only event recorded in these sections. Some ot her important shifts have been recognized in the Upper Maastrichtian a nd Lower Danian sediments. These shifts are related to some palaeogeog raphical events such as platform flexuration which correspond to some regional tectonic reajustments.