8th International Nannoplankton Association Conference
Alessandra Negri, S. Giunta, C. Morigi, L. Capotondi, K.C. Emeis:
A very detailed record of the last deglaciation of the Holocene has been derived from a high sedimentation rate core collected in the S Adriatic Sea (Core Ad 91-17). The core spans the last 14ky, including the sapropel S1 and two volcanic levels. We performed both geochemical (alkenone unsaturation indexes, organic carbon concentrations and stable isotope, delta18O and delta13C) and palaeontological analyses (calcareous nannofossil, planktonic and benthic foraminifera). Chronology is assessed by 14C AMS and by correlation to the ecostratigraphic scheme proposed by Capotondi et al. Our study records fluctuations in both microfauna and nannoflora related to different climatic phases. From the bottom, we recognise a first warming phase, testified to by both the planktonic microfauna and delta18O record. An increasing sea-surface temperature (SST), testified to by both delta18O and alkenone unsaturation indices, characterises the Sapropel S1 interval. Furthermore, Sapropel S1 was interrupted, as testified to by a rapid repopulation by benthic foraminifera. This interruption is also documented by the planktonic microfauna that records a superficial water cooling. Finally, in the sapropel interval, both calcareous nannofossils and foraminifera assemblages show frequency fluctuations of different species (e.g. R. claviger, H. carteri, B. bigelowii, G. ruber, N. pachyderma, G. inflata) that suggest different depositional phases.
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