Marine sediment cores: archive of the Mediterranean Basin. A tool for Holocene climatic and environmental studies

The NextData project has been proposed to develop an infrastructure to retrieve, store and share climatic data from land and marine areas of the Mediterranean Basin. The analysis of marine data infrastructures, which manage data of in situ and remote observations of the seas (GeoSeas, 2014; ICSU World Data, 2014; NOAA, 2014), highlighted that the online data of marine sediment cores are mainly descriptive information rather than quantitative analysis results (e.g. stable isotope data, planktonic foraminifera quantitative data, etc.) and only few of them are typified by references of scientific works. The goal of the NextData archive is to list the type of useful proxies which record the Holocene climatic changes and share them with scientific community. At this aim a conceptual and logical model was defined in order to publish the metadata on SHARE Geonetwork (http://geonetwork-evk2cnr.org/webapp/, last connection: December 2013) and the quantitative data on WDB-Paleo (https://github.com/wdb/wdb, last connection: January 2014). The study area encompasses about 6,000 marine sediment cores, of which 600 were discussed in papers dealing with paleoclimate issues of the Holocene. The highest percentage of these papers concern the planktonic foraminifera (33%) and stable isotopic data (28%), followed by benthonic foraminifera, calcareous nannoplankton, dinoflagellates and AMS14 C proxies, which are discussed in the 15% of these papers. Furthermore, the analysis performed with the algorithms of spatial analysis implemented in a Geographic Information System environment, made it possible to assess the geographical distribution of paleoproxies and to draw maps, which can represent a tool to support paleoclimatic and paleoenvironmental studies. Planktonic foraminifera, stable isotope and AMS 14 C datasets cover the whole Mediterranean Basin; they display a density higher along the coastline of the Italian peninsula than in other Mediterranean zones. The calcareous nannoplankton and pollen data show a higher density in the Eastern Mediterranean Basin. Moreover, we illustrate the role of the geographical distribution of tephra layers or AMS 14C data as proxies that supply constraints for age modelling of marine sequences (Lowe et al., 2007), mostly aimed at evaluating the synchrony/diachrony of the climatic changes in the Mediterranean area (Lowe, 2011).