GENERAL GEOLOGY

Detailed explanation-1: -Biostratigraphy is the branch of stratigraphy that uses fossils to establish relative ages of rock and correlate successions of sedimentary rocks within and between depositional basins. A biozone is an interval of geologic strata characterised by certain fossil taxa.

Detailed explanation-2: -Biostratigraphic units (biozones) are bodies of strata that are defined or characterized on the basis of their contained fossils. Biostratigraphic units exist only where the particular diagnostic feature or attribute on which they are based has been identified.

Detailed explanation-3: -To work well, the fossils used must be widespread geographically, so that they can be found in many different places. They must also be short-lived as a species, so that the period of time during which they could be incorporated in the sediment is relatively narrow.

Detailed explanation-4: -Ammonites, graptolites and trilobites are index fossils that are widely used in biostratigraphy. Microfossils such as acritarchs, chitinozoans, conodonts, dinoflagellate cysts, pollen, spores and foraminiferans are also frequently used.

Detailed explanation-5: -Biostratigraphic correlation uses index fossils to determine strata ages. Index fossils represent assemblages or groups of organisms that were uniquely present during specific intervals of geologic time. Assemblages refer a group of fossils.