Calcareous microfossils by Rathinavel
- 1. CALCAREOUS MICROFOSSILS Presented by Rathinavel K I st M.Sc appplied geology University of madras (Guindy campus) Chennai – 25.
- 2. Contents Microfossil Types of microfossil Calcareous microfossil Foraminifera Morphology Applications
- 3. What is Microfossils ? Microfossils are very small remains of organisms 0.001mm (1 micron ) to 1mm , that require for magnification for study . They are abundant can be recovered from small smples . Providing the main evidence for organic evolution through the time .
- 4. Based on wall , Classified into 2 groups: Organic walled Acritarchs Dinoflagellates Spores Pollen Grains Inorganic walled Diatoms Silicoflagellates Ostracods Conodonts Foraminifera
- 5. Based on the content of species we divided some types they are, Calcareous Microfossils include coccoliths, foraminifera, calcareous dinoflagellate cysts, and ostracods (seed shrimp) Phosphatic Microfossils include conodonts (tiny oral structures of an extinct chordate group), some scolecodonts. Types Of Microfossils:
- 6. Siliceous Microfossils Include diatoms, radiolarians, silicoflagellates, ebridians, phytoliths, some scolecodonts and sponge spicules Organic Microfossils The study of organic microfossils is called palynology. Organic microfossils include pollen, spores, chitinozoans.
- 8. (Calcareous microfossils seen in Electron microscope.)
- 9. Shells composed of calcite(CaCO3) or aragonite. Present in most marine and some non- marine environment. Lives at great oceanic depths characterized by low temperature and high hydrostatic pressure. Calcareous remains are largely or completely dissolved. CALCAREOUS MICROFOSSILS
- 10. There are three principal types of Calcareous Microfossils: i). Calcareous foraminifera ii). Ostracods, and iii). Calcareous nannofossils
- 12. Kingdom : Protista Phylum : Protozoa Subphylum : Sarcodina Class : Rhizopoda Order : Foraminifera The name Foraminifera derived from the foramen a hole through the wall (septa) between each chamber. Calcareous foraminifera are the single celled animals protected by hard shells of calcareous matter. Microscopic in size, range from 0.1 to 1 mm.
- 13. Each chamber interconnected by an opening (foramen) or several openings (foramina) Known from Early Cambrian to recent times and has reached its peak during Cenozoic period. More than 80,000 species of foraminifera are found Most abundant can be studied with low power microscope. Live either on the sea floor or in marine plankton. Their shells called tests which is consists of a single or multiple chambers.
- 14. Morphology Shell morphology and mineralogy form ate the prime basis for identification of species and higher categories of foraminifera. For the classification of Tests, Calcareous foraminifer subdivided into three sub-groups i). Microgranular consists of tight packed, similar size of grains of crystalline calcite. ii). Porecellaneous tests are formed ofsmal,oriented crystals of high Mg calcite.
- 15. iii). Hyaline tests are formed of larger crystals of low Magnesium Calcite & have a glassy appearance, this test can be radial or granular.
- 17. Aperture
- 19. Geological distribution Foraminifera are thought to have been present in present in the Pre-Cambrian seas, but as yet no undepted fossils of this order have been described from rocks older than the Cambrian. They made their first appearance in Cambrian and comparatively rare till carboniferous, but they became prominent and of great geological importance during upper carboniferous and Permian. So, therefore Foramainifera ranging from Cambrian To Recent.
- 20. Applications : Calcareous fossil foraminifer are formed from elements found in the ancient seas they lived in. Thus they are very useful in Palaeoclimatology and Palaeoceanography. They can be used to reconstruct past climate by examining stable isotope ratios of oxygen , and the history of the carbon cycle and oceanic productivity by examining the stable isotope ratios of carbon.
- 21. Foraminifera can also used be utilised in archaeology in the provenacing of some stone raw material types. Some stone types such as limestone, are commonly found to contain fossilised foraminifera. Because of their diversity, abundance, and complex morphology, fossil foraminiferal assemblages are useful for biostratigraphy, and can accurately give relative dates to rocks. The oil industry relies heavily on microfossils such as forams to find potential oil deposits.