Sebastiaan van de Velde^1,2, Pam Vervoort³, Robert Smith^4,5, Clifford Stephen Law² and Kim Irene Currie², (1)Department of Marine Science, University of Otago, Dunedin, New Zealand, (2)Earth Sciences New Zealand, Wellington, New Zealand, (3)University of Birmingham, School of Geography, Earth and Environmental Sciences, Edgbaston, United Kingdom, (4)University of Otago, Department of Marine Science, Dunedin, New Zealand, (5)University of Otago, Dunedin, New Zealand