Micropaleontology and foraminifera
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- 2. Micropaleontology and Foraminifera Exploration in World Prepared by: Amna Qurban 2
- 3. Contents: Introduction Micropaleontology Areas of Study Foraminifera History Morphology Cell structure and Composition Paleoecology and it’s significance Geological Distribution Scope of Foraminifera Conclusion 3
- 4. Introduction: Micropaleontology is concerned with microfossils and Nano fossils (the latter being smaller than 50 µm), the study of which must, of necessity, be carried out using the light or electron microscope. Such microfossils are :- 1 The remains of unicellular and multicellular micro-organisms. 2 The dissociated elements and skeletal fragments of macro-organisms. • They consist of these types: Foraminifera, Ostracods, Coccolithophora, Diatoms, Radiolaria and Dinoflagellates. • Among this, the Foraminifera, ("Hole Bearers") or forams for short, are single-celled protists with shells which can have either one or multiple chambers, some becoming quite elaborate in structure. • Depending on the species, the shell may be made of organic compounds, sand grains and other particles cemented together, or crystalline calcite. • Foraminifera are found in all marine environments, they may be planktic or benthic in mode of life. • Because of their diversity, abundance, and complex morphology, fossil foraminiferal assemblages are useful for biostratigraphy, and can accurately give relative dates to rocks, in petroleum exploration, paleoclimatology etc. 4
- 5. Micropaleontology: Micropaleontology is the branch of paleontology that studies microfossils, or fossils that require the use of a microscope to see the organism, its morphology and its characteristic details. Microfossils are fossils that are generally between 0.001mm and 1 mm in size. Microfossils are a common feature of the geological record, from the Precambrian to the Holocene. They are most common in deposits of marine environments, but also occur in brackish water, fresh water and terrestrial sedimentary deposits. 5
- 6. Areas of Study: Micropaleontology can be roughly divided into four areas of study on the basis of microfossil composition: 1. Calcareous microfossils: include coccoliths, foraminifera, calcareous dinoflagellate cysts, and ostracods (seed shrimp). 2. Phosphatic microfossils: include conodonts (tiny oral structures of an extinct chordate group), some scolecodonts ("worm" jaws), Shark spines and teeth, and other Fish remains (collectively called "ichthyoliths"). 3. Siliceous microfossils: include diatoms, radiolarians, silicoflagellates, ebridians, phytoliths, some scolecodonts ("worm" jaws), and sponge spicules. 4. Organic microfossils: The study of organic microfossils is called palynology. Organic microfossils include pollen, spores, chitinozoans (thought to be the egg cases of marine invertebrates), scolecodonts ("worm" jaws), acritarchs, dinoflagellate cysts, and fungal remains. 6
- 7. Foraminifera: History: The name Foraminiferida is derived from the foramen, the connecting hole through the wall (septa) between each chamber. The studyof Foraminifera has a long history, their first recorded “mention" is in Herodotus (fifth century BC) who noted that the limestone of the Egyptian pyramids contained the large benthic foraminifer Nummulites. In 1835 Dujardin recognized foraminifera a protozoa and shortly afterwards D'Orbigny produced the first classification The famous 1872 HMS Challenger cruise , the first scientific oceanographic research expedition to sample the ocean floor collected so many samples that several scientists, including foraminiferologists such as H.B. Brady were still working on the material well in to the 1880's. Work on Foraminifera continued throughout the 20th century, workers such as Cushman in the U.S.A and Subbotina in the Soviet Union developed the use of foraminifera as biostratigraphic tools. Later in the 20th century Loeblich and Tappan and Bolli carried out much pioneering work. 7 Kingdom : Protista Phylum : Protozoa Subphylum: Sarcodina Class : Rhizopoda Order : Foraminiferida
- 8. Morphology: Foraminifera are single-celled animals protected by hard shells of different types of materials (chitinous, calcareous, agglutinated, and siliceous). They are microscopic in size, and generally range from 0.1 to 1 mm. (approximately the size of a grain of sand or smaller) and some are more than that. Cell (Soft parts of foraminifera) has: Protoplasm (surrounded by membrane) Protoplasm within the shell (test) = endoplasm (dark and granulous) contains: - 1 or more nuclei - systems for cell-secretion (Golgi) - systems for gas-exchange (Mitochondria) - systems for protein-synthesis (Ribosomes) - fluid or gas filled ‘ droplets’ (Vacuoles) Protoplasm outside the test = ectoplasm (transparent) forms pseudopodia Pseudopodia Long strings of ectoplasm (2-3 to 20 times test diameter) Can branch very often, shaping web-like appearance around the test. Surrounded by rather fluid layer. 8
- 9. Diagram showing live benthic foraminiferal style (Brasier, 1980) 9
- 10. Movement of Foraminifera on Slide under Microscope 10
- 11. Cell Structure and Composition: The test of Foraminifera are composed of two different kinds of material :- a) one kind is secreted by the organism b) the other consist of foreign particles gathered from bottom sediments and cemented together to form agglutinated test Some of them are as follows :- Chitinous wall: Composed of chitin, thin and transparent, present in fresh- water benthic foraminifera. e.g. Chitiodendron fronconianom. Agglutinated wall: Only feature for benthic----foraminifer builds its test wall by cementing together exogenous grains (e.g. sand grains, oolites, fine grains of calcite or sponge spicule) by carbonate mineralization. Wall is a simple layer that grades from fine grains inside to coarse grains outside. e.g. Rhabdammina. Calcareous (Ca CO3) wall: Present for both benthic and planktonic foraminifera: (hyaline or porcelaneous). e.g. Globugerina. Hyaline/glassy wall: Transparent, perforate, crystals are radial, with lamellae (laminations) that separated by organic layers. e.g. Rotalina. Porcelaneous wall: Shiny, smooth, crystals randomly arranged. e.g. Miliolina. 11
- 12. Fig:-Examples of wall structures in foraminifera (Brasier, 1980) 12
- 13. Foraminifera, Ramirez beach, Montevideo, Uruguay 13
- 14. Orbulina universa feeding on larva of Brine Shrimp 14
- 15. Paleoecology and it’s Significance: It has been estimated that more than 80,000 species of Foraminifera are described in the literature. Foraminifera are adapted to all aquatic habitats, most in marine waters, but some can exist in salt or brackish water and the member of one family (Allogromidae) live in fresh water. Most are typically slow moving bottom dwellers and some are pealgic. Foraminifera are usually extremely sensitive to environmental condition such as temperature, salinity, bathymetry etc. and therefore their study is significant to understand the palaeoecological condition of the time of their living. The benthonic forms are indicative of the temperature, salinity, depth and bottom conditions while the temperature, bathymetry and paleocurrent patterns are indicated by planktonic forms. 15
- 16. Geological Distribution: Foraminifera are thought to have been present in the Pre- Cambrian seas, but as yet no undented fossils of this order have been described from rocks older than the Cambrian. The Foraminifera found in the sediments are of all the ages ranging from Cambrian to Recent. 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. Again during Triassic they become less abundant, but during Jurassic and Cretaceous they are represented by large numbers, they reached the maximum developed during Tertiary and Recent. 16
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- 18. Scope of Foraminiferal studies: The reason why Foraminifera are important - in oil exploration and - other subsurface work as index fossils (indicators of a particular geological age) lies not only in their abundance but equally in their range of size. This is generally between 0.10 mm and 1.00 mm in diameter and averages about 0.33 mm, equal to the fine sand grade of sediments. Although some are macroscopic and exceed 5.00 mm in diameter, "Larger Foraminifera", and some are smaller than 0.10 mm, "Micro foraminifera". 18
- 19. The reasons for the particular value of foraminifera in stratigraphy: 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. Calcareous fossil Foraminifera are formed from elements found in the ancient seas they lived in. Thus they are very useful in Paleoclimatology and Paleoceanography. They can be used to reconstruct past climate by examining the stable isotope ratios of oxygen, and the history of the carbon cycle and oceanic productivity by examining the stable isotope ratios of carbon. Foraminifera can also be utilized in Archaeology in the provenancing of some stone raw material types. Some stone types, such as limestone, are commonly found to contain fossilized Foraminifera. 19
- 20. Continued….. Stratigraphic markers "tops" based on the first appearance of species and assemblages in ditch cuttings can be applied in correlation which can be carried out without expensive coring. It has existed in abundance since the Cambrian, showing well-marked evolutionary changes useful in stratigraphy. Different families mark the Eras and major time Periods. Many species are planktonic and of worldwide occurrence. When this wide geographical range is combined with a short vertical time range they make excellent index fossils. Many species are restricted in their habit and confined to a particular ecological niche. They are thus particularly useful in interpreting the character of ancient environments. Foram-limestones (larger foraminifera) are well developed in the Upper Paleozoic, The Upper Cretaceous and in the Cenozoic. 20
- 21. Conclusion: Foraminifera are abundant in most marine environments so only small sediment samples (a few grams) are needed to obtain statistically significant numbers of microfossils to perform environmental analysis. They are sensitive to environmental change and their mineralized shells normally get preserved in the sediment after the death of the organism. The quantitative importance of Foraminifera is large and they may constitute a major portion of the Biomass in many marine ecosystems. They must therefore be considered as one of the most significant organism groups living today. Some recent studies indicate that Foraminifera are not only a group of great ecological importance as food organisms for fish and invertebrates, but also play an important role in the turnover of nutrients and energy in the sea. They are extremely useful in Applied Geology, such as in history of Climate, Stratigraphy and in Oil Prospecting. Foraminiferal analyses of dated sediment cores represent a quick and cost efficient way to evaluate possible environmental differences between present and pre-impact (reference) conditions without previous knowledge of the area being examined 21
- 22. References: Books 2008 Dr. P. Jain and Dr. M.S. Anantharaman “PALAEONTOLOGY” Vishal Publishing co. Jalangdhar- Delhi, Pp (58-69). 2008 P. K Mukherjee “ A TEXTBOOK OF GEOLOGY” World Press Private Limited, Pp (307 to 309) 1998 Dr. P. K. Kathal “MICROFOSSIL AND THEIR APPLICATION” CBS Publishers and Distributers, Pp (50-71). 1970 Rhona M. Black “ THE ELEMENTS OF PALAEONTOLOGY” Syndics of the Cambridge University Press, Pp (234-239). Websites en.wikipedia.org/wiki/Foraminifera www.ucl.ac.uk/GeolSci/micropal/foram.html www.mans.edu.eg/FacSciM/english/courses/ 22
- 23. Interesting Fact: You know that sand comes in colors of yellow, white, or gray. Sometimes, if it's volcanic, also black. But what about a pink sand beach? Foraminifera caused such a rare phenomenon in Harbor Island (Bahamas). The pale pink sand beaches, some over 3 miles (5 km) long and 50 to 100 feet (15 to 30 m) wide, are some of the very best beaches in the archipelago. The beach is located 50 mi (80 km) east of Nassau (the capital of the Bahamas) and it is sheltered by a coral reef. The unusual sand is a mix of bits of coral, broken mollusk shells, minute rocks and pink or red shells of Foraminifera, made of calcium carbonate. When Foraminifera die, they are washed up on shore due to the action of the waves, but the shells can reach the shore also as the fish knock them loose when they feed on the fleshy part of the animals. 23