Overview

Project Highlights

  • Builds on current NERC-funded research at University of Birmingham to reconstruct Pliocene palaeo-temperature of the North Atlantic surrounding Iceland.
  • Develops a new terrestrial palaeo-temperature calibration using novel organic geochemical analysis.
  • Integrations new Cenozoic palaeo-temperature record with a wide range of solid earth and climate records to study link between Icelandic Plume, ocean circulation and climate.

The Icelandic Plume is the most vigorous mantle convection cell currently within Earth’s mantle. The Greenland-Scotland Ridge (GSR) is the hotspot track of the Icelandic Plume and forms one of the most important gateways in the global circulation system. Relatively small (c. 100 m) changes in GSR elevation have a strong influence on oceanic circulation. Pulsing behaviour of the Icelandic Plume has driven 100 m-scale changes in GSR elevation on a million-year timeframe throughout Cenozoic time, resulting in variations in oceanic circulation. North Atlantic palaeo-temperature records are required to ask how these circulation changes influence climate. Surprisingly, there is relatively little high quality palaeo-temperature information in the vicinity of the GSR itself.

The few available North Atlantic palaeo-temperature reconstructions are predominantly based on marine sedimentary archives, for which temperature proxies are well established. Recent advances in organic geochemistry have developed the use of branched glycerol dialkyl glycerol tetraethers (br-GDGTs) in organic-rich terrestrial sediments as a proxy for air temperature. Such new tools open the possibility of significantly increasing the number of North Atlantic Cenozoic palaeo-temperature records by analysing lignite-bearing sedimentary packages.

A pilot study of the thick, Pliocene, lignite-bearing Tjörnes sedimentary succession of northern Iceland shows that original palaeo-temperature information is overprinted, but not destroyed, by burial. Several geographically localised palaeo-temperature calibrations currently exist for br-GDGTs. This project aims to produce a single, widely applicable calibration that accounts for a range of burial conditions by combining lab-based experiments and fieldwork. The new Icelandic Pliocene palaeo-temperature record will then be extended back to the Oligocene using lignites from Northern Ireland, Norway and Greenland, with access aided by project partners.

The new Cenozoic palaeotemperature record will be interpreted in the light of an ongoing Birmingham-based General Circulation Model (GCM) study of the effect of GSR elevation on oceanic circulation. This analysis will work alongside and benefit from anticipated IODP drilling in the North Atlantic south of Iceland. Building a more complete understanding of climate change through the Cenozoic will help better predict how anthropogenic climate change might affect the world in the next century.

Residual depth map of the North Atlantic, showing the large topographic swell centred on Iceland supported by the Icelandic mantle plume (Jones et al., 2014).  Arrows mark the Greenland-Scotland Ridge oceanic gateway. Stars mark lignite palaeo-temperature archives at various distances from the plume centre that will be analysed by this project.

Methodology

Generation of the new palaeo-temperature record will follow procedures developed during our pilot study of the Pliocene. Sediment samples will be obtained from fieldwork and visits to our collaborators in Stockholm, Belfast and Munster. Organic extractions from the sediment samples will be done in the Birmingham Molecular Climatology laboratory. The polar fraction, containing the br-GDGTs, will be analysed by HPLC/MS at the NERC Life Sciences Mass Spectrometry Facility. Thermal histories in response to burial and contact heating will be modelled at the University of Birmingham. We will combine this information with lab-based studies of thermal degradation of organic biomarkers and develop a method to extract the true climatic signal and associated uncertainty envelopes from the lignite biomarker data.

Training and Skills

The student will undergo training in organic extractions at Birmingham and will have the opportunity to visit Bristol to learn mass spectrometry techniques. They will explore fieldwork options to sample Cenozoic lignites across the North Atlantic. Collaboration with the GSNI and museum-based collaborators will allow access to and training for study of existing lignite samples. Applications to participate in forthcoming relevant IODP expeditions in the North Atlantic will be encouraged (e.g. IODP, 2017). The student will be encouraged and supported to participate in ongoing tectonic modelling of GSR elevation, and GCM modelling of its effect on oceanic circulation.

Timeline

Year 1: Literature review. Review lignite field/core localities. Visit GSNI to sample N Ireland core material; lab analysis of latter. Write and submit LSMSF grant for HPLC/MS analysis. Devise Iceland field programme in collaboration with Stockholm Museum; carry out field programme summer, end Year 1. Apply to sail with IODP on North Atlantic expedition.

Year 2: Lab analysis of Icelandic material. Thermal history modelling of sedimentary successions.   Generate first version of new palaeo-temperature calibration, leading to new palaeo-temperature record, leading to paper. Plan and carry out second Iceland field season to carry out end Year 2. Potential IODP expedition. Conferences.

Year 3+: Lab analysis of Icelandic material. Update palaeo-temperature record. Integrate palaeo-temperature record with GSR elevation modelling and GCM ocean circulation modelling, leading to paper. PhD dissertation. Conferences.

Partners and collaboration (including CASE)

Dr Rob Raine (Geological Survey of Northern Ireland) will provide access to core through Oligocene lignites and core analysis facilities.

Dr Thomas Denk (Naturhistoriska Riskmuseet, Stockholme) edited the state-of-the-art volume on Icelandic plant-derived sedimentary record and will provide access to samples.

Dr. Christian Pott (Landschaftsverband Westfalen-Lippe, Munster) will provide access to Strauch’s comprehensive sample collection, newly curated in Munster.

Dr Steve Jones (Birmingham) led the pilot study of the Tjörnes succession and is on the lead writing group of IODP-892 "Mantle Dynamics, Paleoceanography and Climate Evolution in the North Atlantic Ocean".

Dr James Bendle heads the Birmingham Molecular Climatology laboratory.

Further Details

Contact Dr Stephen Jones (s.jones.4@bham.ac.uk) for project-specific information. See CENTA web page for information on how to apply and general information (http://www.birmingham.ac.uk/generic/centa).