Buildups from the lower Cambrian Hawker Group, Arrowie Basin: construction, facies and geochemistry

The lower Cambrian carbonates of the Flinders Ranges are richly fossiliferous and contain a highly diverse assemblage of archaeocyaths. Lower Cambrian buildups formed by the aggregation of archaeocyaths, cemented together by calcified microbes, occurred on shallow carbonate platforms in low latitudes. The development of these buildups provides an early example of ecosystem engineering by archaeocyaths. The rigidity of these buildups created topographic relief, while the heterogeneity produced internal cavities that enhanced habitat complexity within benthic ecospace. In this study, buildup architecture is mapped to reveal the heterogeneity, structure and proportional relationship between archaeocyaths and calcified microbes. This centimetre-scale foundation provides contextual framework for deciphering the buildup architecture at millimetre- to micrometre-scale. This scale focuses on the biological composition of archaeocyaths, calcified microbes and associated faunas within the buildup. Additionally, this scale reveals the interaction between individual archaeocyaths and the calcified microbial support, with relevance to bioconstruction rigidity and the development of syndepositional cavities.