PhD: Empty waters? Explaining the absence of macro-organisms in Avalonian late Ediacaran shallow-marine palaeoenvironments

The Department of Earth Sciences, University of Cambridge, is offering a funded PhD studentship in sedimentary geology and palaeontology, as part of the project “Establishing the environmental context for Earth’s first ‘mass extinction’”, funded by the Leverhulme Trust. The PhD studentship is funded for up to 3 and a half years, and the candidate would be expected to start in October 2021.

The wider project seeks to test the evidential basis for the hypothesis that the Ediacaran macrobiota suffered a late Ediacaran extinction event several million years before the Cambrian radiation of crown-group metazoan phyla. The successful candidate will work as part of an international team of palaeontologists and sedimentary geologists, and will use sedimentological approaches and facies characterization to establish why certain late Ediacaran palaeoenvironments in the UK and Newfoundland are seemingly devoid of early animal fossils. Candidates with Earth Sciences/Geoscience backgrounds and some field experience are preferred.

Importance of the area of research concerned:
Global compilations of Ediacaran species occurrence reveal a substantial latest Ediacaran decline in fossil diversity, but these compilations are biased towards fossil-bearing coarse-grained, siliciclastic, shallow marine sedimentary facies. Contemporaneous fine-grained siliciclastic successions from Canada, Norway, the Ural Mountains of Russia, and the U.K. exhibit markedly different fossil assemblages, and a depauperate biota across the supposed ‘extinction’ interval. The successful student will undertake detailed sedimentological and palaeobiological characterisation of neglected depositional environments in Newfoundland (Canada) and the UK to determine the original environments they represent, and why their faunal diversity differs so markedly from that seen in other regions at this time.

Project summary/what will the student do?:
This project will characterize the sedimentology, petrology and palaeobiology of Ediacaran shallow marine sedimentary successions of Newfoundland (Canada) and Shropshire (U.K.) to characterise their depositional environments, and to determine the link between specific facies and fossil taxa.
The student will produce detailed sedimentological logs through multiple sections through the Musgravetown, St. John’s and Signal Hill Groups (Avalon and Bonavista peninsulas, Newfoundland), and the Longmyndian Supergroup (Shropshire), characterising facies and documenting fossil occurrence within individual facies, to reconstruct depositional environments. Petrological study will investigate micro-scale variation in sedimentological structures, permitting refinement of environmental interpretation and sediment sources. The work undertaken by the student will directly contribute to a broader project to establish the true influence of environmental setting on fossil distribution and preservation in Ediacaran shallow marine settings. Findings will be measured against directly comparable datasets from other global localities of similar bathymetry and environmental setting, namely the Ediacara Member (South Australia), Vendian successions of the White Sea region (Russia), and Nama Group (Namibia), to investigate the causes of variation in fossil distributions and sedimentary facies within these globally significant localities. Compilation of information on fossil occurrence and sedimentology within a presence/absence matrix, and statistical analysis of covariance between these datasets, will resolve any links between environmental conditions and palaeocommunity composition.

Training to be provided:
The student will receive training in field based sedimentological data collection and interpretation, sedimentary petrology, palaeontological identification, and statistical methods.