Microfossil distribution patterns and high-resolution δ13C and δ18O curves, calibrated
against planktonic foraminiferal and calcareous nannofossil data, are provided for the Aptian pelagic
Coppitella section of the Gargano Promontory (southern Italy). The succession consists of cyclically
arranged couplets of bioturbated grey marlstones and off-white marly limestones, referable to the
Marne a Fucoidi. In the lower portion of the section, two thin black shales were recognized. The high-resolution
δ13C curve presented here correlates with those of other Alpine–Tethyan sections, albeit with
lower absolute values. The onset of deposition of organic-rich sediments falls at the top of the interval
of unchanging carbon-isotope values, whereas the upper black shale is documented from the interval of
the main Aptian positive δ13C excursion. According to our biostratigraphic data, the deposition of
organic matter in the Gargano Promontory persisted through Early/Late Aptian boundary time. Using
a chemostratigraphic definition, only the lower black shale is referred to the Selli Level. As far as the
biotic response is concerned, the onset of the ‘nannoconid crisis’ is recorded considerably below the
lower black shale, whereas the ‘Globigerinelloides eclipse’ is recorded below and within the upper
black shale. The distribution of meso-eutrophic indices (Zygodiscus spp., radiolaria) vs. moderate-fertility
indices (Rhagodiscus asper and Lithraphidites carniolensis) testifies to a modest increase of surface-water
fertility only throughout the stratigraphically higher black shale. The occurrence of a benthic
foraminiferal fauna, albeit impoverished, in both the basal and upper black horizons clearly documents
dysaerobic rather than completely anoxic conditions on the sea floor. Relative sea-level rise at the time
of the Selli Event in the Gargano Promontory is documented by drowning and foundering of the
Apulia platform margin, situated adjacent to the basin in which the Marne a Fucoidi accumulated.