2013 BAS PhD Studentship - Identification of glacial-time sources for Antarctic deep- and bottom-water masses by geochemical fingerprinting of marine sediments
Supervisors:
Dr. Claus-Dieter Hillenbrand (BAS), Dr. Claire Allen (BAS)
Dr. Alexander Piotrowski (Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge)
The Southern Ocean connects the Atlantic, Indian and Pacific oceans and is a key region linking ice sheets, ocean circulation and global climate. Today, Antarctic Bottom Water (AABW), which is mainly formed on the continental shelves of the Weddell and Ross seas, ventilates much of the world’s deep ocean. Proxy data from marine sediment cores recovered north of the Antarctic Polar Front (APF) suggest that during Late Quaternary glacial periods changes in the bottom- and deep-water circulation of the Southern Ocean enlarged the carbon reservoir of the world ocean, thereby lowering atmospheric carbon dioxide concentrations. The ‘switch back’ to a circulation pattern similar to today at the end of glacial periods may have triggered ice-age terminations. However, direct evidence for glacial deep- and bottom -water circulation south of the APF is lacking. Therefore, it is unclear whether stable carbon isotope (δ13C) records on benthic foraminifera from north of the APF indicate either (i) different glacial-time AABW sources on the Antarctic shelf, (ii) reduced air-sea gas exchange, or (iii) increased biological productivity in the glacial Southern Ocean.
This project will reconstruct the deep- and bottom water circulation south of the APF in various sectors of the Southern Ocean and evaluate its impact on global carbon cycling and climate during the Late Quaternary. It will take advantage of unique sedimentary sequences bearing calcareous foraminifera, which were recovered in the Weddell, Ross and Amundsen seas by BAS and collaborating institutes in Germany and the U.S.A. The project will utilise the distinct chemical signal of neodymium (Nd) isotopes as a water-mass proxy together with benthic foraminiferal δ13C data to:
• Reconstruct regional and Southern Ocean wide circulation changes of deep and bottom water masses during glacial-interglacial cycles of the Late Quaternary.
• Identify possible changes in the source areas and processes of AABW formation during glacial periods, thereby focussing on implications for the glacial extent of grounded ice on the continental shelves in the Weddell, Ross and Amundsen seas.
• Test the hypothesis that during past glacial and interglacial periods the propagation of deep waters from the Atlantic into the Pacific sector of the Southern Ocean was similar to today.
• Decipher whether foraminiferal δ13C records from the deep ocean basins north of the APF were controlled by changes in deep ocean carbon storage and/or ocean circulation.
The successful student will be registered with the University of Cambridge, working jointly at BAS and the Godwin Laboratory for Palaeoclimate Research. She/he will receive training in work on marine sediment cores and the analysis of Nd-isotopes on authigenic coatings of foraminifera and bulk sediments. The student will develop expertise in Antarctic marine geology, isotope geochemistry and palaeoceanography. Applicants should have a good first degree in geology, Earth science, or an equivalent subject, a Masters degree or relevant postgraduate experience and preferably a track record in palaeoceanography or marine/isotope geochemistry.
The NERC PhD Studentship is linked to the British Antarctic Survey Polar Science for Planet Earth programmes Ice Sheets and Chemistry and Past Climate (http://www.antarctica.ac.uk/bas_research/our_research/current/programmes/index.php).
Duration: This NERC funded studentship is expected to last 3.5 years from October 2013.
Salary: Stipend for 2012/2013 was £13,590 p.a. For eligibility go to http://www.nerc.ac.uk/funding/available/postgrad/eligibility.asp
Applications for this studentship should be addressed to Dr Claus-Dieter Hillenbrand, include a covering letter, CV and the e-mail addresses of two referees and sent to basstudentoffice@bas.ac.uk Please quote reference number BASDTG/hill/1
Closing date for applications is 31st January 2013.
For further details about the British Antarctic Survey please see: http://www.antarctica.ac.uk
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