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==An Entry from the AAPG [[2021 Middle East Wiki Write Off]]!==

|Author=Sultan Alghufaily, Ali Alwaheed, and Ali Halal

by Sultan Alghufaily, Ali Alwaheed, and Ali Halal, Saudi Aramco

 

|Competition=[[2021 Middle East Wiki Write Off]]

 

 

Biostratigraphy is the study of the temporal and spatial distribution of fossil organisms throughout the geological time scale. This science is based on the concept of evolution and extinction ([[:file:AlghufailyetalFigure1.jpg|Figure 1]]) of species at specific times where the process is not repeatable. The most important fossils for biostratigraphy are known as index fossils, which are abundant, widely distributed, easy to recognize, and occur only during a narrow time span. Preservation of fossils vary significantly, an entire organism or just a part of it. This is dependent on the nature of the fossilized organism, mechanism of preservation, and diagenesis of the rock unit. Fossils can be subdivided based on their size in three main groups: macrofossils (large enough to be visible without a microscope), microfossils (between 0.001mm and 1 mm in size) (figure 2) and nannofossils (between 5–60 μm in size). Biostratigraphy is used to identify rock formations which can occur at outcrop and/or in the subsurface and correlate time-equivalent units over large distances irrespective of lithology that can be variable due to change in environment and basinal configuration. Biostratigraphy plays an important role in petroleum exploration and production as it allows a number of cost-effective, quick and logistically simple ways to determine the ages of sedimentation, reservoir characterization, correlation and well site operation where field specific bioevents are determined and tested for consistency. Other applications include determining palaeoenvironment, paleobathymetry, assessing thermal maturity and highlight the possibility of having self-generating source rock strata.

 

[[file:AlghufailyetalFigure1.jpg|thumb|300px|{{figure number|1}}Examples of the marine and continental organism evolution ad extinction throughout the Paleozoic and Mesozoic.<ref name=Cascalesminanaetal_2016>Cascales-Miñana, B., Diez, J.B., Gerrienne, P. and Cleal, C.J., 2016. A palaeobotanical perspective on the great end-Permian biotic crisis, Hist. Biol., 28, 1066–1074.</ref>]]

[[file:AlghufailyetalFigure1.jpg|thumb|300px|{{figure number|1}}Examples of the marine and continental organism evolution ad extinction throughout the Paleozoic and Mesozoic.<ref name=Cascalesminanaetal_2016>Cascales-Miñana, B., Diez, J.B., Gerrienne, P. and Cleal, C.J., 2016. A palaeobotanical perspective on the great end-Permian biotic crisis, Hist. Biol., 28, 1066–1074.</ref>]]

[[file:AlghufailyetalFigure2.jpg|thumb|300px|{{figure number|2}}Main microfossils disciplines that are used in the oil industry and/or paleoenvironmental use (Avada Oil and Gas Course).]]

[[file:AlghufailyetalFigure2.jpg|thumb|300px|{{figure number|2}}Main microfossils disciplines that are used in the oil industry and/or paleoenvironmental use (Avada Oil and Gas Course).]]