Antarctic climate history at the onset of glaciation: Was there ice in the greenhouse?

Programme website: http://inspire-dtp.ac.uk

Project Rationale:
During the extremely warm global ’greenhouse’ period ~50 million years ago, Antarctica was mostly ice free and hosted temperate forests. Subsequent cooling over many millions of years resulted in a steady deterioration of Antarctic climate at the end of the Eocene Epoch, eventually culminating in widespread glaciation at the beginning of the Oligocene Epoch (~34 million years ago). Both climate variability prior to ice-sheet development and possible existence of glaciers, or even small ice sheets, during greenhouse intervals are debated. Recent studies support glacial activity in the lead up to major glaciation (Scher et al., 2014; Passchier et al., 2016; Carter et al., 2017), but, controversially, more substantial ice cover in East Antarctica during earlier (and warmer) time intervals of the Eocene has also been interpreted (Gulick et al., 2017).

Fundamental questions need to be answered about both long- and short-term Antarctic climate variability and the timing of ice-sheet development through the greenhouse to icehouse transition. Importantly, were there phases of cooling and extensive ice accumulation in Antarctica during presumed greenhouse periods? Extensive ice-sheet cover today, however, limits rock exposures on Antarctica. Most information on Antarctic greenhouse climate history is instead derived from marine sediment cores, but it is challenging both to obtain drillcores from the Antarctic margin and to extract palaeoclimate signals from those cores.

Methodology:
This project will gain new insight into the early climate history of Antarctica through application of established sedimentological, mineralogical, and geochemical methods, along with development and application of novel proxy and core imaging methods for reconstructing Antarctic palaeoclimates and variations through time. The project will focus on the investigation of new drillcore sequences to be recovered on upcoming International Ocean Discovery Program (IODP) Expedition 379 to the Amundsen Sea, West Antarctica (scheduled Jan-Mar 2019), combined with study of existing drillcores distributed around the Antarctic margin from past scientific drilling projects.

The methodological approach for the project will specifically focus on: (i) identification and characterization of sand- and pebble-sized ice-rafted debris through core imaging and grain size analysis, (ii) geochemical analysis of the silt fraction, and (iii) mineralogical and stable isotope analysis of clay minerals through X-ray diffraction (XRD) and elemental analyser–isotope ratio mass spectrometry (EA-IRMS). This combined multi-proxy approach to investigate detrital weathering and erosional products shed from terrestrial environments on Antarctica will provide information on changes in weathering states, climatic variations, and glacial activity.

Training:
The INSPIRE DTP program 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 in Ocean and Earth Science at the National Oceanography Centre. Regular collaborative visits will be made to British Antarctic Survey (BAS). Specific training will include:

● Dating and stratigraphy of Antarctic margin sediments
● Sedimentological, geochemical, and core imaging studies
● XRD clay mineral analysis
● Compositional and grain-size analysis of the terrigenous sediment fraction
● Oxygen and hydrogen isotope analysis of clay minerals using EA-IRMS (SEAPORT Stable Isotope Labs, Univ. Southampton)
● Sediment fabric analysis using microtomography (µ-Vis facility, Univ. Southampton)
● Correlation, integration, and interpretation of multi-proxy datasets for palaeoclimatic reconstructions

Beyond the training opportunities and exchanges associated with the INSPIRE DTP, there will be opportunities to travel to drillcore repositories in Bremen, Germany, and Texas, USA, for sample collection. Travel to international scientific meetings to present project results will also be encouraged and supported.