Isotopic signatures in crystalline carbonates: the role of amorphous precursors

Past environmental conditions (e.g., temperature) cannot be directly measured.

However, they are recorded in a measurable way in paleoclimate proxies, which are physical, chemical and biological materials preserved within the geological record in paleoenvironmental archives, and that can be analyzed and correlated with environmental parameters.

Carbonates are one of the most important paleoenvironmental archives as they record the formation environmental conditions in their chemical and isotopic composition.

However, to use them as paleoenvironmental proxies is essential that the original signatures are preserved.It has been reported that the formation of many carbonates from different geological settings involves the precipitation of amorphous precursors (non-classical nucleation pathways) and their subsequent transformation into crystalline phases.

This formation pathway could modify the original signatures restricting the use of carbonates as paleoenvironmental proxies.

Yet, the effects on the isotopic composition of carbonate minerals due to phase transitions from amorphous precursors have been largely overlooked compared to the modifications due to diagenetic or depositional processes.

Then, the main goal of the project is understanding how different pathways and transformation mechanisms of amorphous precursors control the isotopic composition of the final crystallinepolymorph.

This aim will be tackled under two approaches abiotic and biogenic conditions and combining mineralogical, microbiological and geochemical tools. The results could generate new guidelines for optimizing paleoclimate reconstructions using ancient carbonate minerals.

This project, its impact and outcome, as well as the training in cutting-edge techniques I will get in the host and secondment host laboratories, complementary to my expertise and transferable skills, will transform me in an independent, highly competitive researcher helping me to obtain a stable scientific position.