Advanced spectrometric analysis of biomineralization mechanism of Neoproterozoic eukaryotic microfossils and early animals (Bocaina Formation, Corumbá Group, Brazil)

Abstract

The Bocaina Formation crops out in the state of Mato Grosso do Sul, SW Brazil, beneath the black limestones and shales of the Tamengo Formation where the important biomineralizers Corumbella and Cloudina are found (> 542 Ma). Zircons from interbedded tuffs from the upper part of the Bocaina Formation were dated at 555.18 ± 0.30 Ma (ID-TIMS U-Pb). Both formations are part of the Ediacaran Corumbá Group. The Bocaina Formation consists essentially of stromatolitic dolostones, with phosphatized microbialites intercalations that yielded the fossils described here. The assemblage includes two categories: (i) microfossils and (ii) tubular shelled organisms. All the above examples took benefit from high definition 2D or 3D images. This proposal aims to apply advanced spectroscopic characterization, including electron microprobe (EPMA); micro-Raman, Laser Ablation ICP-MS and nanotomography to investigate morphology, taphonomy, composition, supramolecular organization, texture and biogeochemical nature of early life, to answer questions regarding the roots of biomineralization process in Neoproterozoic unicellular and multicellular organisms. Synchrotron techniques such as XRF, XRD and microXAS will be applied at the beamline microXAS of the Swiss Light Source, Paul Schrerrer Institute, Villigen, Switzerland. (AU)