About the Project
From a UK perspective the TOAE and associated extinctions and recovery has been extensively researched in the Cleveland Basin, but much less is known about the event in the rest of the UK. This is because whilst there is a narrow band of Toarcian outcrop in England from Yorkshire through the Midlands to the South-West, the rocks are poorly exposed. Toarcian rocks do crop out on the Dorset coast, but here they are present as a highly condensed, carbonate facies, quite unlike the expanded shales of the Yorkshire coast. However, there exists at the British Geological Survey (BGS) an unparalleled archive of rock cores from deep boreholes passing through the Lower Jurassic across the UK. The cores have been described sedimentologically and were split to recover macrofossils, which are now in the Registered Specimens collections in the BGS. For the Lower Jurassic time period tens of thousands of Registered Specimens exist in the collections, most of which have never been looked at since the original descriptions of the rock cores. Further, within the past few years there have been two excavations of Toarcian rocks from inland sites in Somerset: Strawberry Bank and near Seavington St Michael. Here the Toarcian is much more expanded than at the Dorset coast, but as limestone-marl carbonate rather than mainly limestone or shale facies. Both of these excavations have yielded considerable numbers of macro and microfossils, and bulk samples for processing.
The primary aim of this project is to investigate regional patterns of benthic macrofossil extinction and recovery through the Toarcian hyperthermal event, by integrating existing data from the Yorkshire coast, with new data from rock cores in the BGS and excavated specimens from SW England. This will involve the student spending considerable amount of time at the BGS working through the Registered Specimen collections from the relevant cores from the Pliensbachian (the stage before the Toarcian) through the Toarcian times. Benthic macrofossils will be identified, and species range charts will be constructed and plotted against the established stratigraphy. Collections from the Somerset excavations are also available will be similarly dealt with, and bulk samples will be processed for additional fossils. All the benthic macrofossils in the study will be assigned to trophic guilds via an inferential modelling approach where key palaeoecological traits define the likelihood of predator-prey interactions and consumption. Meta-communities will then be analysed using trophic network modelling, so to investigate changes in ecosystem structure and function across the extinction and recovery intervals. The student will also analyse biogeographical recovery in the aftermath of the extinction event by incorporating data from Pliensbachian-Toarcian sections outside the UK, derived from the Paleobiology Database.
Remírez, M.N., and Algeo, T.J. (2020) Carbon-cycle changes during the Toarcian (Early Jurassic) and implications for regional versus global drivers of the Toarcian oceanic anoxic event. Earth-Science Reviews 209: 103283. https://doi.org/10.1016/j.earscirev.2020.103283
Wignall, P.B., Newton, R.J. and Little, C.T.S. (2005) The timing of paleoenvironmental change and cause-and-effect relationships during the early Jurassic mass extinction in Europe. Am. J. Sci. 305: 1014-1032.
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