Applications of micro-fossil in bio statigraphy
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This document provides an overview of biostratigraphy and microfossils. It defines biostratigraphy as using fossils to determine the relative age of rock strata. Microfossils, which are fossils less than 0.5mm in size, are commonly used for biostratigraphy. Various types of microfossils like foraminifera, radiolaria, and diatoms are described. Biostratigraphic units defined by fossil occurrences like zones, assemblage zones, and interval zones are also outlined. The document discusses uses of biostratigraphy in fields like stratigraphy, correlation, and sequence stratigraphy. Microfossils are concluded to be very useful for reconstructing past environments from deep sea sediments and in the
Applications of micro-fossil in bio statigraphy
- 2. Contents of Seminar INTRODUCTION MICRO FOSSILS BIOSTRATIGRAPHY BIOSTRATIGRAPHY UNITS USES OF MICRO FOSSILS CONCLUSIONS REFERENCES
- 3. Introduction Palaeontology- Is the study of fossils to determine the structure and evolution of extinct animals and plants and the age and conditions of deposition of the rock strata in which they are found. Fossils- A remnant or trace of an organism of a past geologic age, such as a skeleton or leaf imprint, embedded and preserved in the earth's crust. Types of fossils are- vertebrate fossil , invertebrate fossil , plant fossils , micro fossils , nonofossils. Microfossils-A microscopic fossil , generally less than 0.5 millimeter in size, such as a protozoan, bacterium, or pollen grain. A fossil so small that it can be studied and identified only with a microscope. The interpretation of the depositional environments of the strata. Types are:- Lithostratigraphy, Biostratigraphy, Magnetostratigraphy, Isotope stratigraphy, Chronostratigraphy. • Biostratigraphy-is the identification of fossils found within sedimentary rock strata as a method of determining the relative geologic age of the rock and the arrangement of fossils in rock strata. Distribution of Biota according to Stratigraphic levels
- 4. Microfossils: Microfossils- Microfossils size measures between 50 -500 µm. Example Acritarchs, Palynofossils, Chitinozoan, Conodonts, Foraminifera, Ostrachoda, Dinoflagellates, Fossil Algae, Phytoplanktons, Fungi, Scholecodonts, Radiolarians, Nanofossils, Calcareous nanofossils, Diatoms etc. Requires microscopes like phase contrast, binocular, sterobinocular microscopes, SEM, TEM etc.,
- 5. Foraminifera – wholly marine Sarcodine Protozoa that secrete both calcareous and organic-cemented tests. Lives in both benthonic and planktonic modes . Radiolaria – wholly marine Sarcodine Protozoa that secrete a siliceous test. Only planktonic mode of life. Calcareous nannofossils – marine planktonic algae that secrete calcareous plates. Includes coccoliths.
- 6. Diatoms – algae that secrete siliceous frustules. Can live in both freshwater and marine environments, in both benthonic and planktonic modes of life . Ostracods – crustaceans that secrete a bivalved calcareous carapace. Can live in both freshwater and marine environments, in both benthonic and planktonic modes of life . Dinoflagellates – calcareous or, more commonly, organic-walled marine algae. Planktonic, but has a benthonic resting stage.
- 7. Biostratigraphy- Biostratigraphy is the elements of stratigraphy that deals with the remains or evidences of former life in a strata and with the organization of stata into units based on their fossil content. strata are characterized by their fossil content organize into units based on fossil characteristics (assemblage, ranges etc.) not large fossils (which are rare) but microfossils Fossils are extremely common in marine sediments; in fact they are the main constituent in many cases. Organisms are sensitive to their environment – live where they are comfortable – We can use these relationships to determine something about the environment Biostratigraphy: based on appearances and disappearances of species This assumes that either, species appeared (evolved) or disappeared (became extinct) globally Or conditions changed locally causing species to migrate
- 8. Biostratigraphic units:- Primary data of biostratigraphy: presence or absence of a fossil taxon in a geologic horizon Biozone (often just "zone"): Rock unit characterized by one or more taxa that permit it to be distinguished from adjacent rocks. Consider the hypothetical data at right. As we explore these, note that the definition of most biozones requires some element of uncertainly or inferrence. Taxon Range Zone: Between global FAD & LAD of that taxon. - Requires some inferrence - Global correlation of horizons bearing the fossil taxon. Concurrent Range Zone: Intersection of the taxon range zones of two or more taxa. Interval Zone: Interval (global) between two successive FADs or two successive LADs Assemblage Zone: Characterized by 3 or more taxa in natural assemblage (fuzzy boundaries, as FADs and LADs aren't simultaneous.) Special Case: Oppel Zone: DEFINED by FAD or LAD of one taxon, but characterised by additional taxa. Named for Albert Oppel, the first to use non-arbitrarily defined biozones . Abundance Zone (also called Peak Zone, Acme Zone): Subset of teilzone where index species reaches some higher level of abundance: useful locally, but almost certainly environmental rather than time-related. That isn't to say that there is no time signal necessarily.
- 11. 11 A B C D E Commonly used; lower and upper limits of zone are defined by lowest and highest occurrence of zonal name-bearer (taxon E) Time line-2 Time line -1
- 12. 12 A B C D E Most commonly used; boundaries defined on first or last occurrences of specified taxa FAD LAD
- 13. 13 A B C D E Commonly used: Zonal boundaries defined by the overlapping ranges of two or more specified taxa (D & E)
- 14. Basic biostratigraphy is concerned with the recognition of fossils and the relative position of their occurrences in space and time. Various fossil groups can be found in different sedimentary environments. The two main environments are land (terrestrial) and Sea (marine Aqautic). The use of basic biostratigraphy in different sediment types
- 15. Terrestrial sediments, spores and pollen In terrestrial sediments, spores and pollen are the fossil group to use.The limitation on the use of spore/pollen is the amount of oxidation experienced by the sediments after deposition. Oxygen will remove organic material (spores/pollen) from the sediments. Spores can be used in Devonian (approx. 400 myrs) to recent sediments, pollen in Upper Cretaceous (approx. 80 myrs) to recent sediments. Both can be found blown into marine environments in considerable amounts.
- 16. Palynomorphs Palynomorphs (dinoflagellates, acritarchs and tasmanites) can be used in Permian ( approx. 260 myrs) to recent sediments and in most sediments types. Since their preparation includes the dissolution of the surrounding sediments, their use is more expensive than nannofossils. The possible stratigraphic resolution can be high. Recently, the use of organic grain size and shape as environmental indicators has been developed and is apparently useful, especially in sub-recent sediments.
- 17. Foraminifera Foraminifera can be used in all marine sediments which have not be leached of calcareous material, i.e. from shallow marine to middle bathyal. Their stratigraphic resolution can be high and their association with certain depositional environments makes them good environmental (water depth) indicators. Foraminifera can be found in sediments of Carboniferous (approx. 360 myrs)to recent age. Their preparation cost is lower than that of palynomorphs, unless thin-sections have to be used.
- 18. Silica enriched sediments In silica enriched sediments, siliceous microfossils such as diatoms and radiolarians can be of use. The stratigraphic resolution can be high, especially in the Tertiary (approx. 65 myrs), but schemes are still under development for other time frames. Their preparation cost is similar to that of foraminifera. It is good practice to always analyse at least two of these fossil groups per sample to provide a cross check. This reduces the chance of unexpected sedimentary circumstances leading to erroneous age and environmental estimates. The age estimates can be numeric if the fossils encountered in a sample can be related to the global zonation schemes which exist today.
- 19. Biostratigraphy is the use of fossils to date sediments and reconstruct past environments, and enables ages to be applied to isolated samples. Any fossil has the potential of being used biostratigraphically, however, in deep-sea sediments retrieved using coring equipment, the best fossils to use are those that are small and abundant in the core samples. Microfossils are thus the most appropriate types of fossils to use when investigating DSDP (Deep Sea Drilling Project) and ODP (Ocean Drilling Program) material. Foraminifera are protozoans with a skeleton that is readily preserved in the fossil record. Both planktic (i.e., living in the water column) and benthic (i.e., living on the sea floor) species occur and have for decades been subject of extensive research. Their paramount importance for (paleo-) environmental studies is well-known in academy as well as in industry.
- 20. Applied Micropaleontology: unravelling the petroleum systems with foraminifera. Biostratigraphy and applied micropaleontology are essential tools in exploration activities for oil and gas industry. Microfossils, such as foraminifera, are of high importance since they occur in a variety of marine environments and through the geological time. TNO’s Geobiology team offers applied research in micropaleontology combining up-to-date academic research and practical expertise to assist the E&P industry. Some of the microfossils that can be derived from deep-sea sediments and used for biostratigraphical purposes are described. Microfossils are very useful in scientific ocean drilling and in the oil and gas industry because their tiny size and great abundance in marine sediments allows geo- scientists to reconstruct ancient environmental conditions, establish the relative age of the sedimentary layers (i.e., fossils found in lower or deeper strata are older than fossils found in higher or shallower strata; fossil occurrences can be used to identify the relative order of past events), and correlate the sedimentary layers with other localities around the world.
- 21. CONCLUSIONS Biostratigraphy-is the identification of fossils found within sedimentary rock strata as a method of determining the relative geologic age of the rock and the arrangement of fossils in rock strata. Fossils speaks about bioevents in the Past Continuation Discontinuation New appearance Disappearance Diversification Synthetic Biostratigraphy helps in understanding the past biological changes in the past Signifies Time and Rock concept.
- 22. REFERENCES 1976 , Hollis.D. Hedberg , Internatational sratigraphic guide , A Willy – Interscience Publication, New York , page no: 48-62. 1993 , T.N. & E.L. Taylor , The Biology and Evolution of Fossil Plants and Animals , Standard publication , page no: 54-56 http//www.microfossil.org www.wikipedia.org/wiki/application of fossils http//www.osti.gov/biostratigraphy/biostratigraphy application
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