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Overview

Project Highlights:

  • Builds on current NERC-funded research at University of Birmingham to reconstruct Pliocene palaeo-temperature of the North Atlantic surrounding Iceland
  • Uses novel organic geochemical analyses of multiple terrestrial sedimentary successions to extend our palaeo-temperature record back to Oligocene time
  • Integrates 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.

Overview:

The Icelandic Plume is the most vigorous mantle convection cell within Earth’s mantle at present. 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 Cenozoic 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 (GDGTs) in organic-rich terrestrial sediments as a proxy for air temperature. Such new tools open up the possibility of significantly increasing the number of North Atlantic Cenozoic palaeo-temperature records by analyzing lignite-bearing sedimentary packages.

The centrepiece of this project is to obtain new palaeo-temperature records from Miocene-Recent lignites exposed onshore Iceland. The new Icelandic palaeo-temperature record will be extended back to the Oligocene using lignites from Northern Ireland, close to the south-eastern end of the GSR. There are several other opportunities to work on Cenozoic lignites from Norway and Greenland.  

The second principal project aim is to build a more comprehensive understanding of the relationship between mantle convection, ocean circulation and climate in the North Atlantic. Elevation changes at the GSR will be modelled based on our existing Cenozoic mantle temperature records. The resulting predictions of ocean circulation changes will be compared with the new North Atlantic palaeo-temperature record. This analysis will work alongside and benefit from IODP drilling in the North Atlantic south of Iceland planned for 2021. Building a more complete understanding of climate change through the Cenozoic has the potential to help better predict how anthropogenic climate change might affect world in the coming century.

Left.  Residual depth map of the North Atlantic, showing the large mantle convectively supported swell centred on Iceland.  Yellow stars mark potential lignite sample locations.  Right.  Example of a Pliocene Icelandic lignitite-bearing sedimentary succession already sampled during our pilot work: Skiefá waterfall, Tjörnes Peninsula.

Methodology

Generation of the new palaeo-temperature record will follow procedures developed during our current study of the Pliocene. Sediment samples will be obtained from fieldwork to Iceland and visits to our collaborators in Stockholm and Belfast. 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. Modelling of GSR elevation will be based on two decades of work by Jones and collaborators on pulsing plume head processes that underpinned the development of drilling proposal IODP-892 (Parnell Turner et al., 2015; IODP, 2017).

Training and Skills

The student will work within an experienced team to arrange access to existing sediment samples, and to plan and carry out two field campaigns in Iceland. Training for organic geochemical preparation work will be provided, as well as opportunity to visit Bristol to learn mass spectrometry techniques. Training in computational techniques to model GSR elevation will be provided, in collaboration with the IODP-892 writing group. Subject to IODP scheduling, the student will apply to sail with IODP-892 in 2021-22, leading to synergy with this international programme to study mantle dynamic, paleoceanography and climate evolution in the North Atlantic.

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. Generate first version of new palaeo-temperature record, leading to paper. Modelling Oligocene-Miocene elevation history of GSR. 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 and GSR elevation modelling, leading to paper. PhD dissertation. Conferences.

Partners and collaboration (including CASE)

Dr Thomas Denk (Naturhistoriska Riskmuseet, Stockholme) edited summary volume on Icelandic plant-derived sedimentary record. He will provide access to samples in Stockholm, advise on fieldwork in Iceland, and contribute to data interpretation.

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

Dr Steve Jones (PI) is on the lead science writing group of IODP-892 "Mantle Dynamics, Paleoceanography and Climate Evolution in the North Atlantic Ocean"; project results will be written up in collaboration with this team, based primarily at Cambridge, Southampton and Scripps (USA).

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).