Article – Liberating fossils from carbonates

Foraminifera recovered using the Lab system


A research team led by the Camborne School of Mines, part of the University of Exeter, has quantified the way in which electric pulse disaggregation can improve the liberation and recovery of foraminifera from well-cemented carbonate rocks.

Foraminifera, or forams, are the fossilised shells of single-celled marine organisms. They are important to research as the chemical composition of their shells can be analysed to determine the chemistry of the ocean at their time of formation – critical for our understanding of past climates, which can help to inform about possible future “warmer than present” scenarios. Further to this, forams can also be used to determine the age and sedimentary environment of marine strata, as well as to estimate thermal maturity of rocks (Sharma et al., 2018) – all of which are of use to the hydrocarbon and energy sector.

Charlotte Beasley, a PhD student at CSM, compared material disaggregated in a SELFRAG Lab with that obtained via disaggregation using state-of-the-art conventional methods. These other methods utilised acetic acid and Calgon. Subsequently, disaggregated samples were assessed in terms of quantity of forams recovered and quality of recovered materials (e.g., whether there was damage to the fossils).

 

Six images of forams liberated using EPF, acetic acid and Calgo. EPF treated show some attached material and fracturing, acetic acid showd siddolution, Calgon shows lots of material still attached.
Images of forams recovered after the various treatment methods, showing fractures (F) adherent material (S) or dissolution (D).

Some dissolution of forams occurred using acetic acid, while Calgon was mostly ineffective at breaking apart the heavily lithified rocks. With EPF some fracturing of forams occurred, but overall recoveries were good and the preservation of the forams was superior to those liberated using acetic acid, many of which were etched or partially dissolved.EPF treatment took minutes compared to multiple days required for the other methods – a clear inidcation that this method can be utilised by climate researchers to save time.

The full open access article can be found in vol. 39 (p. 169–181) of the Journal of Micropalaeontology.

 

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