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A postgraduate research opportunity at the University of Otago.


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Dr Christina Riesselman, Dr Georgia Grant (GNS Science)


The Southern Ocean is a prime driver of Earth's climate cycles, and understanding how this system responded to past intervals of rapid change will be essential to addressing society's future climate challenges. However, the vigorous circulation of the Antarctic Circumpolar Current means that sedimentation is variable and hiatuses are common in Neogene sequences. Our ability to evaluate the timing of past change in the Southern Ocean is therefore limited by a lack of chronostratigraphic reference sections where continuous sedimentation and excellent paleomagnetic signals allow biostratigraphic datums to be definitively calibrated.

This project will take advantage of three exceptional new sediment cores drilled by IODP Expedition 383 in 2019 in the central and eastern South Pacific ocean to develop the first chronostratigraphic reference section for the Southern Ocean. All three cores are continuous with no evidence of hiatuses. Basal ages range from 4.2 to 8.2 Ma. Each has an excellent shipboard magnetostratigraphy, and the upper portion is additionally tuned to the global benthic delta18 O stack. The project will develop a detailed diatom biostratigraphy from at least two of these cores, resolving the position of first and last occurrence datums relative to paleomagnetic tie points to refine the age ranges of key taxa that are currently subject to significant uncertainties. Refined datums will then be integrated with existing global data using constrained optimization modeling, producing a global Southern Ocean chronostratigraphic reference sequence.

This project is ideally suited to a student who's interested in (micro)paleontology and biostratigraphy and enjoys microscope work. Selection is contingent on receiving a competitive University of Otago Doctoral Scholarship.


Christina Riesselan

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