Paper No. 96-6
Presentation Time: 9:35 AM
RECOGNITION OF GLOBAL LOWER DEVONIAN EVENTS IN THE SPANISH CENTRAL PYRENEES; A CONODONT PERSPECTIVE
Six major Global Events are recognised in Lower Devonian strata worldwide; they are from oldest to youngest: the Silurian/Devonian Event (S/D), the sulcatus Event (=Lochkovian/Pragian Event, SE), the basal Zlíchovian Event (BZE), the upper Zlíchovian Event (UZE), the Daleje-Cancellata Event (DCE) and the Choteč Event (CE). Most of them have not a definitive, worldwide unique lithological expression such as the thin black/dark shales and limestone intercalations observed in younger Middle and Upper Devonian rocks. In the Spanish Central Pyrenees (SCP) four of them can be recognised on the basis of different criteria. The S/D Event is aligned with the Scyphocrinites lobolithes occurrence around the base of the Devonian in several sections; it is close to the lowest Pyrenean record of Icriodus woschmidti. Around the L/P Event a smooth lithological change is coupled with a conodont turnover and a marked reduction in number of taxa that seems to be common in European strata suggesting a Pragian conodont crisis. Besides, in two Pyrenean sections a sharp increase in Magnetic Susceptibility values has been measured. The LZE is alligned in the Baliera area with a sharp lithological change represented by the onset of platy limestone overlying a thick quartzitic succession. The UZE shows a remarkable change in the composition of the conodont record, affecting, at least, four relevant genera. In one section, Baliera 6, it is coupled by a marked lithological change represented by the onset of a dark micritic thin interval of limestone and shale. Neither the DCE nor the CE have been recognised yet in the Pyrenees.