Lead supervisor: Nicholas J. Butterfield, Earth Sciences
Co-supervisor: Maarten van Hardenbroek, Physical Geography, Newcastle University
Brief summary:
Diverse, abundant and exceptionally preserved fossils in the mid-Miocene Clarkia Formation offer one of the most complete views a a palaeo-lacustrine ecosystem on record
Importance of the area of research concerned:
Lakes host one of the planet’s major biomes, with constituent organisms providing a diagnostic account of local to regional ecology, environment and climate. The fossil record promises similar insights into ancient systems, but is deeply compromised by post-mortem processing. But there are exceptions. Palaeo-lake Clarkia from the mid-Miocene of northern Idaho is famous for its exceptionally preserved leaves, but there is an equally extraordinary biota of aquatic crustaceans, arachnids and insects that has been entirely overlooked. What's more, the succession includes ~840 richly fossiliferous annual varves, with a potential for tracking ecological dynamics on scales from seasons to centuries. In concert with the accompanying records of phytoplankton, fungi and terrestrial vegetation - and geochemical signatures for methane cycling - the Clarkia offers a uniquely resolved view of a mid-latitude lacustrine ecosystem during the Mid-Miocene Climatic Optimum. Significantly, the MMCO is considered the best available analogue for how the modern Earth system will respond to ~5 degrees of global warming.
Project summary :
The project will focus on the extraction and biological reconstruction of individual fossils in the first instance (predominately crustaceans, larval insects and mites), but with an eye to recovering the ecological and environmental dynamics of the whole Clarkia system. The abundance and variety of carbonaceous remains means that taxon-specific isotopic signatures (C, N, O, H) can be incorporated into the analysis, offering unique insights into trophic structure, methane cycling, and overall lake function. Recent documentation of ~900 annual varves offers a unique opportunity to track these dynamics on scales from seasons to centuries.
What will the student do?:
The student will conduct at least one season of field work in Idaho in order to document the stratigraphic and palaeoenvironmental context of fossiliferous horizons, and to assemble a corresponding set of field samples. Laboratory work will focus on the gentle extraction/isolation of carbonaceous fossils, followed by anatomical reconstruction and taxonomic analysis. Trophic interactions and larger scale community dynamics will be reconstructed by integrating these palaeontological data with taxon-specific isotopic analyses (C, N, O, H) - with a particular focus on the role of methane. The overall structure (holomictic vs. meromictic) and metabolic status (net autotrophic vs. heterotrophic) of the palaeolake will be addressed in the context of the Mid-Miocene Climatic Optimum.
References - references should provide further reading about the project:
Höfig, D., Zhang, Y.G., Giosan, L., Leng, Q., Liang, J., Wu, M., Miller, B. & Yang, H. 2021. Annually resolved sediments in the classic Clarkia lacustrine deposits (Idaho, USA) during the middle Miocene Climate Optimum. Geology 49, 916–920.
Butterfield, N.J., & Harvey, T.H.P. 2012. Small carbonaceous fossils (SCFs): a new measure of Paleozoic palaeobiology. Geology 40:71–74.
van Hardenbroek, M., et al. 2018. The stable isotope composition of organic and inorganic fossils in lake sediment records: Current understanding, challenges, and future directions. Quaternary Science Reviews 196, 154–176.
Applying
You can find out about applying for this project on the Department of Earth Sciences page.