High-resolution mapping and correlation of the syntectonic Sant Lloreng del Munt alluvial fan and fandelta deposits show that proximal alluvial fan sequences, d efined on the basis of sediment supply changes linked to tectonic and/or geomorphic processes acting in the alluvial fan catchment area, are not directly correlationable with the similar magnitude and frequency, transgressive-regressive sequences recognizable in the fan-delta deposits. This fact clearly points to a clear basinward variation in the factors con trolling the sequential arrengement of alluvial accum ulations attached to an active foreland basin margin and advises againts the current abuse in the use of the classical sequence stratigraphy methodology in order to analyse the Paleogene syntectonic deposits of the South Pyrenean foreland basin