Micropaleontological analysis of different fossil groups in sedimentary rocks provides information on geological and paleoclimatic phenomena, through biostratigraphy and paleoecology. Biostratigraphy uses signals related to the evolution of organisms (appearance, disappearance and acme), whereas paleoecology is based on analysing those organisms that more sensitive to environmental parameters. The occurrence of indicative species as proxies of temperature, salinity, depth, concentration of nutrients, etc., allows for determining the characteristics of the environment in which the organisms lived and where the rock sedimented.
The IGG’s Micropaleontology Laboratories carry out studies on radiolarians, calcareous nannofossils and ostracods. The radiolarians are planktonic protozoans, that live both at the surface and in deep ocean waters. Their dimensions can range from 30µm to 2 mm in diameter and their skeletons, after the transformation from opal to quartz, can be found in different types of sedimentary rocks and siliceous carbonates. The time interval over which radiolarians are found ranges from the Cambrian to the present. Calcareous nannofossils are the skeletal remains of marine planktonic unicellular algae, living in the photic zone, ranging in size from 2 to 65 μm. Calcareous nannofossils can be found in marls and limestones, but also in marly sandstones and silts, which haven’t been subject to metamorphism, strong diagenesis and/or meteoric alteration. The time interval for calcareous nannofossils ranges from the upper Trias to the present. Ostracods are mainly benthic organisms found in both marine sediments and continental deposits. The average size for adult specimens is less than 1 mm. Thanks to the presence of a calcified bivalve carapace that can easily fossilize, ostracods are stored in sediments ranging from Cambrian to the present.