Palynology is a scientific discipline concerned with the study of plant pollen, spores, dinoflagellates, acritarchs, chitinozoa and certain organic-bodied microscopic planktonic organisms, in both living and fossil form.
The term Palynology is derived from the “study of dust” (from Greek: παλύνω palunō, “strew, sprinkle” and -logy) or “particles that are strewn”. Often defined as “the study of microscopic objects of macromolecular organic composition (i.e., compounds of carbon, hydrogen, nitrogen and oxygen), not capable of dissolution in hydrochloric or hydrofluoric acids”.
Plants produced numerous spores and pollen for reproduction. The first fossilised spores date back to the Middle Ordovician. These diverse fossils may be dispersed by wind as well as water, and are deposited in many sedimentological environments and are also present in marine environments. Due to their robust nature, they are a valuable tool for understanding past ecosystems (both terrestrial and marine).
Dinoflagellates are a group of mainly marine phytoplankton, although freshwater members of the group are also known. They are highly sensitive to sea surface temperature, salinity and depth. Dinoflagellates produce resting cysts during periods of dormancy, and these resistant capsules (dinocysts) are common components of marine palynological assemblages. The first fossil evidence for dinoflagellates (as dinocysts) occurs during the Late-Triassic.
Acritarchs and Chitinozoans are some of the oldest know palynomorphs, both having proven utility for dating early Palaeozoic rocks long before the origin of the other palynomorph groups. Both of these ancient groups are enigmatic, and their true biological affinities are not certain; over the decades they have been attributed to algae, plants, fungi or animals. Chitinozoans are important stratigraphic markers in the Ordovician, Silurian and Devonian. Acritarchs are the main biostratigraphic fossils used for the early Palaeozoic.
Stratigraphic palynology is a branch of micropalaeontology and palaeobotany, and is the study of fossil palynomorphs from the Pre-Cambrian to the Holocene. Their often-rapid evolution through time makes them useful for oil and gas exploration and exploitation. The robust composition of these organic fossils means they are easily preserved in a variety of environments, providing biostratigraphic ages to a wide range of depositional facies.
The pollen and spore assemblage can be used to determine onshore palaeoenvironments if their ecological affinity in known. Dinocysts can also be used to indicate certain environmental niches along the continental shelf. Palynofacies studies can also provide further palaeoenvironmental information. Palynofacies is the study of the complete organic assemblage, including both palynomorphs and kerogen. Kerogens represent the non-palynomorph component of the organic residue, including vitrinite (wood) and AOM (amorphous organic matter, from algae and plant resins). The proportion of terrestrial and marine indicators are counted in each sample, producing a graphical representation of paleoenvironmental changes throughout a well or section.
Palynomorph colour can be used as a proxy for thermal maturity; progressive darkening of the fossil occurs with increasing thermal maturity. A palynology and palynofacies study can be used to assess the source rock potential for generating oil and gas