Sumário do projecto (Project abstract):

 

The micropaleontological study of Calcareous nannofossils is developed as a proxy for palaeoenvironmental interpretations, during the Neogene and Quaternary (last 20 Ma), in both (1) oceanic and (2) costal (oceanic island, continental neritic and transitional-lagoonal) domains.

 

In the first case, Global Change timing and nature are addressed through the study of the major changes in the composition of Neogene Calcareous nannofossil assemblages and in the morphometric properties of cocolith morphological parameters of certain species (e.g. Coccolithus pelagicus). The study is based on selected ODP cores retrieved from the North Atlantic Ocean (Site 552A, SU 90/08 and MD 2087), South Atlantic Ocean (Site 704A, ODP Leg 177), Western Indian Ocean (Site 709B), Western Pacific Ocean (Site 806B) and South Pacific Ocean (PALEOPAC 1,3 e 4) carried out in connection with seven other European institutions under the funded EU program Training and Mobility of Researchers (Coccolithophorid Evolutionary Biodiversity and Ecology Network - CODENET; EC TMR - ERB-4061-PL- 97-0764) as well as within the collaboration protocol with the Department of Geology of the University of Salamanca.

 

In the second case, the taphonomical interpretation of Neogene carbonate facies, generally dominated by rich and diversified invertebrate fossil assemblages, as well as Quaternary siliciclastic facies (e.g. gravity cores CD110 W90, PE 109-13) allows the study of noisy shallow sedimentary records of nannoliths, strongly influenced by coastal mechanisms of transport and sedimentation, which may retain certain Global Change signals expressed by changes in local paleoproductivity. These records include sedimentary sequences, sometimes generated by storms and/or tsunamis, on reef, open beach, estuaries and lagoon (palaeo)environments. Due to its multidisciplinary nature, this project incorporates national specialists on malacology, sedimentology, coastal evolution and vulcanology and is also supported by international specialists on Calcareous nannoplankton biostratigraphy and paleoecology and on present day reef environments, as scientific advisors of the project. This project is closely integrated with several other national and international projects in progress (PRAXIS/PCNA/P/CTE/12/96; PRAXIS/PCNA/C/CTE/9/96; DGXII EU - ENV IV CT 96 0297) to which contributes with pertinent information concerning the importance of Calcareous nannofossils in palaeoenvironmental analysis.

 

The peculiar nature of the sedimentary post-mortem processes acting on nannoliths allows addressing them in palaeoenvironmental analysis as a marine tracer, an innovative way that will be tested and complemented by ecological and macropaleontological (taphonomical) studies. Calcareous nannoplankton is also used as a biostratigraphic marker for dating Neogene sedimentary sequences. This last approach will result, in the presentation, for the first time, of volcano-sedimentary fossiliferous sequences of the Atlantic Islands of Madeira (Porto Santo) in the same Neogene’s biostratigraphical framework of the marine sedimentary basins of the lusitanian ocidental (Tagus Basin) and meridional (Algarve Basin) margins of the Iberian Peninsula.