Cyclostratigraphy of the Middle to Upper Ordovician successions of the Armorican Massif (western France) using portable X-ray fluorescence

To expand traditional cyclostratigraphic numerical methods beyond their common technical limitations and apply them to truly deep-time archives we need to reflect on the development of new approaches to sedimentary archives that traditionally are not targeted for cyclostratigraphic analysis, but that frequently occur in the impoverished deep-time record. Siliciclastic storm-dominated shelf environments are a good example of such records. Our case study focusses on the Middle to Upper Ordovician siliciclastic successions of the Armorican Massif (western France), which are well-studied in terms of sedimentology and sequence stratigraphy. In addition, these sections are protected geological heritage due to the extraordinary quality of the outcrops. We therefore tested the performance of non-destructive high-resolution (cm-scale) portable X-ray fluorescence and natural gamma-ray analyses on outcrop to obtain major and trace element compositions. Despite the challenging outcrop conditions in the tidal beach zone, our geochemical analyses provide useful information regarding general lithology and several specific sedimentary features such as the detection of paleoplacers, or the discrimination between different types of diagenetic concretions such as nodules. Secondly, these new high-resolution data are used to experiment the application of commonly used numerical cyclostratigraphic techniques on this siliciclastic storm-dominated shelf environment, a non-traditional sedimentological setting for cyclostratigraphic analysis. In the lithological relatively homogenous parts of the section spectral power analyses and bandpass filtering hint towards a potential astronomical imprint of some sedimentary cycles, but this needs further confirmation in the absence of more robust independent age constraints.

Molecular Paleobiology of the Echinoderm Skeleton

Molecular paleobiology provides a promising avenue to merge data from deep time, molecular biology and genomics, gaining insights into the evolutionary process at multiple levels. The echinoderm skeleton is a model for molecular paleobioloogical studies. I begin with an overview of the skeletogenic process in echinoderms, as well as a discussion of what gene regulatory networks are, and why they are of interest to paleobiologists. I then highlight recent advances in the evolution of the echinoderm skeleton from both paleobiological and molecular/functional genomic perspectives, highlighting examples where diverse approaches provide complementary insight and discussing potential of this field of research.

Country Calls: A Creative Practice of Deep Time Walking in Darug Country

This article presents my personal story, as a non-Indigenous settler woman, of walking along a ridge close to my home at the foot of the Blue Mountains west of Sydney, after the fires of 2019 to 2020. In this article, I want to invite the reader into my love of this country through sharing my record of this walking over a 12-month seasonal cycle. Every walk presented me with new understandings of this Country where I live, which I already knew as Darug Country, having explored the nature of this country in collaboration with my Darug friends Jacinta and Leanne Tobin.