Dr C Pearce, Dr M Clare, Dr S Bohaty, Prof Gavin Foster
No more applications being accepted
Funded PhD Project (Students Worldwide)
About the Project
Over geological timescales, the silicate weathering feedback process is thought to have kept Earth’s climate within habitable conditions by regulating atmospheric CO2 levels [1]. According to this hypothesis, enhanced continental weathering under warmer, wetter, conditions supplies more carbonate ions to the oceans, thereby increasing the rate of carbonate burial and atmospheric CO2 removal, while colder, drier, conditions reduce the rate of weathering and hence CO2 drawdown. Although the relationship between atmospheric CO2 and global temperature is well established, the weathering response to climatic perturbations is less well understood. Recent studies have even suggested that changes in continental uplift (i.e. global topography) may play a more significant role than climate in controlling the long-term rate of silicate weathering [2].
This project aims to characterise the links between global climate and silicate weathering by investigating geochemical and sedimentological changes through intervals of major climate change in the geological record. High-resolution and high-precision records of weathering-sensitive isotopic systems will be measured across warming and cooling events that occurred during the Paleogene interval between 66 and 23 million years ago. Such events include the Paleocene-Eocene Thermal Maximum, Middle Eocene Climatic Optimum, and Eocene-Oligocene Climate Transition, and together will enable the effectiveness and significance of the silicate weathering thermostat to be assessed.
Variations in the supply of dissolved and particulate material to the ocean are reflected in the composition of seawater and the sedimentary record respectively. Coupling high-resolution records of geochemical and sedimentological changes through past climatic events will therefore establish whether a relationship exists between global warming and continental weathering, as well as assess the extent to which this may have regulated the global carbon cycle. Characterisation the rate and nature of silicate weathering during past climatic events will be achieved using established proxies such as the radiogenic strontium (87Sr/86Sr) and stable lithium (d7Li) isotope systems [3]. These records will be compared to changes in sediment transportation and burial established via textural and grain-size analysis of sedimentary cores, with material and sites selected to cover a range of near-shore to distal basin depositional environments. Samples will be obtained from key intervals of Cenozoic climate change via the International Ocean Discovery Program (IODP), and will be supported by outcrop-based fieldwork in the Italian and Austrian Alps, visits to IODP core repositories, and the opportunity to join sampling cruises where appropriate.
The SPITFIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the National Oceanography Centre. Specific training will be provided in state of the art analytical and isotopic techniques that include Thermal Ionisation Mass Spectrometry (TIMS), Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS), major and trace element analysis, and grain-size analysis. The student will also receive training in the characterisation and preparation of sediments from deep-sea cores and outcrops, marine sedimentology, stratigraphy and foraminiferal taxonomy, and will gain a variety of skills that are in high demand for both academia and industry. As part of the NOCS Graduate School the student will join an internationally recognized team of postgraduates and researchers specialising in geochemistry and palaeoceanography.
Funding Notes
This SPITFIRE project is open to applicants who meet the SPITFIRE eligibility, alongside other exceptional applicants and will come with a fully funded studentship for UK students and EU students. To check your eligibility and find information on how to apply click this link: http://www.spitfire.ac.uk/how-apply
UK applicants and EU students who meet the RCUK eligibility criteria please apply to SPITFIRE using the apply feature.
This project is also open to applicants who DO NOT meet the SPITFIRE funding eligibility criteria via applying to GSNOCS: https://studentrecords.soton.ac.uk/BNNRPROD/bzsksrch.P_Login?pos=7184&majr=7184&term=201819
References
[1] Walker and Hays (1981). A negative feedback mechanism for the long-term stabilisation of Earth’s surface temperature. J. Geophys. Res. 86, 9776-9782.
[2] West et al. (2005). Tectonic and climatic controls on silicate weathering. Earth Planet. Sci. Lett. 235, 211-228.
[3] Pogge von Strandmann et al. (2013). Lithium isotope evidence for enhanced weathering during Oceanic Anoxic Event 2. Nat. Geosci. 6, 668-672.