QUANTITATIVE PALYNOLOGY - A TOOL FOR THE RECOGNITION OF GENETIC DEPOSITIONAL SEQUENCES - APPLICATION TO THE BRENT-GROUP

Palynological data were made available from core samples of sediments of the Brent Group which were penetrated by an exploration well. Quant ification of the numerous samples supplied frequencies oi palynofacies components and microfossil amounts. The existence of both microfossil -rich and microfossil-poor samples reflects the high heterogeneity of the sediments. Factor analysis and automatic clustering of the palynof acies components show gradations from continental to marine settings a nd from low to high energy depositional environments. Each sample is s uccessively analysed, processed and plotted at its driller depth on a summary sheet. The sheet shows trends, i.e. ''palynological sequences' ' which can be compared to the genetic sequences interpreted from the sedimentological study. More reliable microfossil-rich samples are use d for other multidimensional analyses. They further constrain the prel iminary results and supply complementary results on microfloristic ass emblages and a few other trends (sediment transport for instance). In high energy settings, the poor preservation of the biological material often precludes the identification of palynological sequences, in con trast with the low to medium energy depositional environments in which palynological sequences often match the genetic sequences defined by the sedimentological analysis. In most cases, the rare discrepancies a re erased by constructive discussions between palynologists and sedime ntologists.