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Evaluating U-Pb and Sr isotopic compositions of late Ediacaran carbonate rock from drill cores to asses preservation of geochemical signatures

Marine carbonates are potential archives of geochemical proxies, such as U-Pb and Sr isotopes, which can be utilized in the reconstruction of past climate conditions and ancient seawater composition. The ability to confidently reconstruct environmental conditions in the past times is of great importance since they are linked with changes in the biosphere. For example, the Ediacaran-Cambrian transition was a period of time where significant evolutionary change modified the biosphere. An intact, continuous record of environmental conditions will help to understand better the timing, nature and sequence of events that preceded or accompanied such changes in biodiversity. However, carbonate rocks are susceptible to numerous post-depositional processes (such as: oxidative weathering, diagenesis, burial, lithification, deformation, dissolution and reprecipitation), which may alter the geochemical record. Additionally, detrital components may increase the complexity of the geochemical signature and the carbonate composition.

Thus, we have to understand and identify the presence or absence of such processes, before extracting meaningful geological information from these archives. Laser Ablation – Inductively Coupled Plasma – Mass Spectrometry (LA-ICP-MS), is a tool that offers spatial resolution when performing geochemical analyses, which may help to interpret the geochemical data. Here, we combine observations from U-Pb and Sr isotopic systematics supported by trace element abundances to identify domains that are indicative of post-depositional processes, over protracted time and variable in their extent.

Details

Author
André Navin Paul1, Axel Gerdes1, Marjorie Cantine2, Maria Ovtcharova3
Institutionen
1Goethe Universität Frankfurt, Germany; 2University of Washington, USA; 3Université de Genève, Italy
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/gpmy-be61