Microfossils And Their Application

Name- Sachin Yadav

Roll No.-163060014

Microfossils- What are they ?

• Mineral Walled microfossils study – Micropaleontology

• Organic walled microfossils study – Palynology

Why study Microfossils ?

• Size

• Much Diversity

• Abundance

• Specific Association

• Easy to extract

1. Foraminifera

• Size generally less than 0.5mm

• Test of having tectinous ,agglutinated or calcareous

• Inhabiting marine or brackish water environments

Planipiral involute

Elphidium

Planipiral evolute

Spirillina milioline

Quinqueloculina biserial

Heterohelix

trochospiral

Ammonia

2. Calcareous Nannofossils

• Size range is 5-60µm

• Shape is hollow sphere composed of calcareous plates, called coccoliths

• Habitat is particularly in zones of oceanic upwelling or pronounced vertical mixing region

• Useful for the statistically valid result

http://www.ucl.ac.uk/GeolSci/micropal/images/calc/caldiag05.gif

3. Diatoms

• Unicellular algae ;external skeleton (a frustule)

• Size range of frustules is 5 – 2000 µm

• Algae with siliceous wall

• Marine and fresh water ; many occur in polar ice caps to hot thermal springs

• Jurassic – Recent

http://www.ucl.ac.uk/GeolSci/micropal/diatom.html

4. Ostracode

• Calcareous or chitinous carapace • 0.5 mm to >5 mm. • Benthic and planktic • All aquatic environments and also moist soils • Ordovician – Recent • Good indicator of palaeoenvironment

http://www.ucl.ac.uk/GeolSci/micropal/ostracod.html

5. Palynomorphs

• Unicellular algae; organic wall. • 20 – 150 µ • Symbiotic, parasitic or as independent autotrophic planktons. • Marine, lagoonal and lacustrine. • Permian – Recent. • Good biostratigraphic potential

a. Acritarchs

b. Dinoflagellates

c. Spore and Pollen

http://lanwebs.lander.edu/faculty/rsfox/invertebrates/protozoa.html

Application of Microfossils Application of Microfossils

1. Petroleum Exploration 1. Petroleum Exploration

3. Development of Field

Core and SWC of Interested Interval Core and SWC of Interested Interval

2. Appraisal of Discoveries 2. Appraisal of Discoveries

Correlation between appraisal and Discovery well Correlation between appraisal and Discovery well Reservoir Distribution and Reserve Estimation Reservoir Distribution and Reserve Estimation

1. Exploration of prospect

Biozonation Biozonation Coring point selection Coring point selection Terminal depth decision Terminal depth decision Stratigraphic monitoring

while drilling Stratigraphic monitoring

while drilling

It’s worth of crore while Horizontal Drilling monitoring-

Source-Geological Survey of the Netherlands

Biostratigraphy

Graphic Correlation - Graphic Correlation -

• Line of correlation

• Rate of rock accumulation

• Hiatus and hiatal intervals

https://www.geol.umd.edu/~tholtz/G331/lectures/331biostrat2.html

Environment Interpretation on the basis of Assemblage :-

(modified after Tewari , 2010)

Fig.-Map is showing the two sampling stations in the Arabian Sea and the Bay of Bengal

Estimation Of Carbon Export Flux to Deep ocean

• Microfossils give the refinement of geological time scale specially in Cenozoic

• They are very sensitive to environment even a degree temp. difference will cause

assemblage differences

• Very good Index fossil ( Short Life span , Wide geographic distribution)

• Isotopic study of microfossils test gives clue about paleo-temperature

• Global Sea Level Curve using Phytoplankton

• Precise Age determination of geological formation

• Well Correlation during petroleum exploration

• Use in Basin modelling

• Use as maturity index of the oil prone source rock (Spore and Pollen)

• More Diverse the benthic microfossils than the planktic and vise-versa for abundance

Conclusion

1. LOEBLICH, A. R., Jr. and TAPPAN, H., 1987. Foraminiferal genera and their classification.

New York: Van Nostrand Reinhold Company, 2 vol.

2. JAUHRI, A. K., 1994. Carbonate buildup in the Lakadong Formation of the South Shillong

Plateau, NE India: A micropaleontological perspective.

3. Armstrong Howard , Brasier Martin 2004 ;Microfossils, 2nd Edition

4. Internet references

http://www.ucl.ac.uk/GeolSci/micropal/

https://www.geol.umd.edu/~tholtz/G331/lectures/331biostrat2.html

http://www.wiley.com/legacy/wileychi/stjohn/supp/Chapter_3_Marine_Microfossils_and_Biost

ratigraphy.pdf

Reference:

Thank

You !!!