Decoding the Icelandic sedimentary record of northern hemisphere glaciation

Project highlights

• Builds on significant investment by Birmingham and the Natural Environment Research Council to exploit sedimentary archives of North Atlantic palaeoenvironmental change.
• Complete our new radiometric + magnetographic + biostratigraphic age model for the Tjörnes sequence, the thickest sedimentary succession in Iceland.
• Re-assess timing, causes and consequences of Bering Strait oceanic gateway opening and intensification of the Northern Hemisphere Glaciation.

Project overview

The Tjörnes sequence is the thickest sedimentary succession exposed onshore Iceland (c. 875 m).  Its high sedimentation rate, fossil and biomarker content, accessibility and position in the North Atlantic near the Arctic Polar Front make it an internationally important record of the global cooling since late Miocene time that led to the modern bi-polar glaciation.  Among the important environmental changes recorded by the Tjörnes sequence are: the faunal exchange event that marks initial opening of the Bering Strait, which established a Pacific-Arctic-Atlantic oceanic connection; the mid Piacenzian Warm Period, a potential analogue for our future climate; and the onset of Icelandic lowland glaciation that signals intensification of the Northern Hemisphere Glaciation (iNHG).  Since 2018 we have been working to update the age model for the Tjörnes sequence and integrate it with nearby marine core-based records.  Our partially revised age model already has significant outcomes (Hall et al., 2022): we supported the hypothesis that the mid-Piacenzian Warm Period is not recorded in the lower part of the Tjörnes sequence; we disproved the hypothesis that Atlantic-to-Pacific faunal exchange occurred 2 million years before Pacific-to-Atlantic faunal exchange after the Bering Strait oceanic gateway opened; and we disproved the hypothesis that establishment of Pacific-Arctic-Atlantic connection directly caused the iNHG.

In this CENTA project, we aim to re-date the upper part of the Tjörnes sequence that contains the record of glaciation.  During the late Miocene, Iceland had only small upland glaciers.  The iNHG caused the sudden expansion of ice to cover the lowland and coastal regions including Tjörnes.  This onset of lowland glaciation in Iceland is clearly recorded within the Tjörnes sequence as the boundary between the Höskuldsvík Group (cycles of basaltic lavas intercalated with sub-aerial, non-glacial sediments) and the Breiðavík Group (cycles of lavas intercalated with glacial diamictites).  The intercalated lavas and sediments offer an excellent opportunity for combined radiometric and magnetostratigraphic dating of the onset of lowland glaciation and the subsequent periodicity of glacial/interglacial cycles.  We also aim to revise the biostratigraphy of the entire Tjörnes sequence, with special reference to the dozens of bivalve mollusc shell beds that document onset of Pacific-Arctic-Atlantic oceanic connection.

Methodology

This is a multidisciplinary project that will build on and add new dimensions to our work on the Tjörnes succession since 2018.  New radiometric ages form backbone of the revised age model.  These will be integrated with existing magnetostratigraphy to refine the age model.  Paleontological samples from our own fieldwork and from museum-based collaborators will be processed and interpreted.  A composite stratigraphic section will be built from detailed sedimentary logging and field mapping by us and collaborators.  All of this information will be integrated within the context of our unique virtual outcrop of the entire Tjörnes succession, built from several years of drone-based mapping (Allison et al., 2022).  We also plan to use the virtual outcrop as an outreach tool to display the museum material and new scientific results.

Training and skills

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training.  One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.

This project would suit a student with a background in any Earth Science field including (but not limited to) Palaeontology, Physical Geography or Geology.  Through the course of the project we will provide training in skills including fieldwork, labwork for radiometric dating and palaeontological sample preparation, museum skills, virtual outcrop development, composite stratigraphic column development, scientific writing and presenting.  There are also opportunities to develop skills in science communication, public engagement and community organising, including getting involved with other projects in the supervisors’ research groups.

Partners and collaboration

Jon Todd (Natural History Museum) offers specialist knowledge in mollusc systematics and collections, and their use in oceanic gateway reconstructions.  Christian Pott (Westphalian Museum of Natural History, Germany) and Thomas Denk (Swedish Museum of Natural History) offer access to collections from the Tjörnes sequence.  Dan Barfod (Scottish Environmental Research Centre) is facilitating the radiometric dating.  Áslaug Geirstóttir is expert in the Icelandic record of glaciation.  Steve Jones currently leads three other international projects researching the relationship between tectonics, volcanism and environmental change in the North Atlantic surrounding Iceland.  These partnerships offer a range of participation possibilities, including marine research expeditions.

Possible timeline

Year 1

Process samples for Ar-Ar dating.  Organise and carry out fieldwork in Iceland.  Processing of palaeontological samples.  Visit museum collaborators to work on Tjörnes collections.

Year 2

Integration of Ar-Ar dating results with existing magnetostratigraphy to complete Tjörnes age model.  Integration of new palaeontological data.

Year 3

Integration of all new datasets within our Tjörnes virtual outcrop model.  Submission of scientific results for publication.  Work with Icelandic collaborators on related outreach projects.

How to apply

Details about how to apply for this project can be found here. We suggest you also read our helpful document about applying for a PhD.

For more information on the CENTA DTP, including eligibility, please visit the CENTA website.