MAGNETOSTRATIGRAPHY AND BIOSTRATIGRAPHY OF CRETACEOUS-TERTIARY CONTINENTAL DEPOSITS, AGER-BASIN, PROVINCE-OF-LERIDA, SPAIN

At Fontllonga (Northeast Spain, Province of Lerida) a nearly continuou s outcrop covers the stratigraphic interval from the Maastrichtian to the Thanetian in continental deposits. Magnetostratigraphy of the sect ion was determined from 72 samples. The magnetic polarity sequence was satisfactorily correlated with chrons 32R to 26R (top of Lower Maastr ichtian to Lower Thanetian). Chron 29R, in which the K/T boundary occu rs, is unambiguously recognizable considering the biostratigraphic dat a (charophyte, ostracod, palynomorph). The K/T boundary occurs in the uppermost part of the Microchara cristata subzone, which includes Late Cretaceous and Early Palaeocene species. This subzone is interpreted as an interval of crisis, following the Late Maastrichtian extinctions and preceeding the Palaeocene radiation. No Ir-rich horizon has been yet found in this -section. The stratigraphic position of the last din osaur remains, found in the chron N-31 interval, leaves open the quest ion of a causal link between the extinction of Cretaceous reptiles and the K/T event.