mikrofosszilis

Mikrofossilis, or microfossils, are tiny fossilized remains or parts of organisms, typically less than one millimeter in size. They are found in sedimentary rocks and sediments worldwide, especially in marine environments. Their small size makes them visible mainly under light or electron microscopes, and they are often concentrated in a specific microfossil fraction after sample preparation.

Microfossils can be calcareous, siliceous, or organic-walled. Major groups include foraminifera and coccolithophores (calcareous), diatoms and radiolarians (siliceous), ostracods and conodont elements, as well as pollen and spores (palynomorphs). Acritarchs and other organic-walled forms are also important. Preservation varies with mineralogy and diagenesis, but these tiny remains can survive long geological timescales.

Applications include biostratigraphy for dating and correlating sedimentary units, paleoenvironmental and paleoclimatic reconstructions, and petroleum geology, where microfossil assemblages help identify stratigraphic boundaries and reservoir intervals. Isotopic analyses of certain calcareous microfossils provide past temperature and ocean-chemistry records.

Methods involve collecting core or outcrop samples, concentrating the microfossil fraction, and examining specimens under light microscopy or scanning electron microscopy. Preparation may use acid dissolution to remove carbonate, oxidation to break down organics, and sieving. The field of study is micropaleontology, with palynology focusing on pollen, spores, and related organic-walled forms.