Key Facts
- The study of marine planktonic and benthonic microfossils.
- Wide stratigraphic distribution from Cambrian to Recent
- Superabundant, can make up >90% of biomass in marine, lacustrine and terrestrial environments, therefore a readily available, cost-effective tool in geological investigations
- Reconstruct palaeobathymetry via morphogroup analysis
- Provides accurate biostratigraphy with high-resolution robust biozonation scheme
- Rapid sample analysis offshore providing key stratigraphic information at decision points in real time
- Paleoenvironmental analysis facilitates understanding of sediment supply, basin fill and depositional setting (geological evolution of a basin)
Why choose micropalaeontolgy?
- Versatility. Utilising multiple fossil groups including foraminifera, radiolaria, ostracods, diatoms with each providing stratigraphic value and key events to provide accurate stratigraphic framework of subsurface. Lithological observations also can be made
- With their rapid evolutionary rates and widespread global distribution Zonal Markers are a powerful tool providing high-resolution chronostratigraphic breakdowns at global and regional scale. Reliable zonal events to help identify and confirm formation tops and bases leading to confident decision-making.
- Fast results & cost effective. Quick and inexpensive samples processing for routine and wellsite projects
- World-leading expertise in-house. Largest group of micropalaeontologist within the industry sharing open plan office, leads to consistent biostratigraphy across wells.
- Widley applicable, broad stratigraphic distribution from Cambrian to Recent. Found in marine, lacustrine and terrestrial environments and a wide range of sediments such as calcareous muds, clays, silts and chalk etc
- Applicable to different real-time drilling scenarios from fast-paced horizontal sections (bio-steering), to picking casing points and assisting with TD, monitoring HPHT wells and high-resolution data acquisition during exploration wells.
Introduction to Micropalaeontology
Micropalaeontology is a discipline of palaeontology mainly concerned with fossils (generally >63 microns) that require microscopes for study including foraminifera, ostracoda, radiolaria and diatoms.
Associated identification of key minerals, fragments of small invertebrates, evidence for bioturbation and drilling artefacts (i.e. mud additive) are also important during analysis. Microfossils have great utility in accurately interpreting the stratigraphic age and environment of deposition.
Diatoms
Are a major group of unicellular algae, producing silica skeletons, and living as solitary organisms or as part of colonies. They are photosynthetic, generating around 20% of the oxygen produced on our plant annually. They take a variety of shapes, including; zig-zags, ribbons, fans or stars. Fossil evidence indicates this group originated in the Early Jurassic, and inhabit both marine and non-marine environments. They have undergone rapid evolution making them useful biostratigraphically, especially from high latitudes, found in marine and non-marine environments.
Foraminifera
Foraminifera inhabit most marine-marginal marine environments and are often very abundant, accounting for over 90% of deep sea biomass. They are single-celled protists with an external shell/test composed of calcium carbonate, aragonite or cemented agglutinated grains. They are a principal microfossil group used to age-date and correlate marine sedimentary rocks of Late Palaeozoic, Mesozoic and Cenozoic age. Moreover, planktonic foraminifera which are geographically widespread and have rapidly evolving lineages and some smaller benthonic foraminifera are widely used for regional stratigraphy.
Ostracods
Ostracods are a class of Crustacea, sometimes informally known as “seed shrimp”. These tiny crustaceans have bivalve-like shells protecting their inner bodies; these shells are chitinous or calcareous, and their preserved remains date back to the early Ordovician. In marine environments, they inhabit the upper layers of the ocean floor sediments. They can also be found in freshwater environments, as well as in humid forest soils in the terrestrial realm. They can be used for biostratigraphic delineation and are also very useful for palaeoenvironmental interpretation, indicator of palaeoshorelines and plate distribution. Very useful when integrated with other groups.
Radiolaria
Radiolaria single-celled microplankton that produce intricate mineral skeletons usually composed of silica. They are found throughout the ocean systems of the world, and their skeletal remains rain down onto the ocean bed as a siliceous ooze. This group has been present since the Cambrian, and their rapid evolution throughout geological time makes them an excellent biostratigraphic tool. Global distribution and biostratigraphically important when calcareous fossils have been dissolved.
Cambrian to Holocene Biostratigraphic Tool
Micropalaeontology has proven to be a reliable biostratigraphic tool for rocks dating ranging from Cambrian to Holocene (modern day).
Palaeoenvironments and Paleaobathymetry
Microfossils are highly sensitive to environmental changes and can be present from the terrestrial (ostracods and diatoms) to the deep marine (foraminifera, radiolaria, ostracods, diatoms). Therefore, relative changes in a microfossil assemblage composition throughout a section can be a versatile tool to interpret the environment of deposition and distance from palaeo-shoreline.
Principally this is achieved by investigating:
- The causal association between microfaunal distribution (abundance and diversity) and sea levels.
- Particular benthonic foraminifera genera and species proliferate in specific environments which can be characterised based on their Morphogroup characteristics.
- Distribution of planktonic microfossils (foraminifera, radiolaria, diatoms) in the pelagic regime reflects distance from shore and the degree of open marine connectivity which can be distinguished into key zones.
