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Faye Nelson standing at cryogenic magnetometer.Training and technical support for Otago Paleomagnetic Research Facility

Email faye.nelson@otago.ac.nz

PhD title
Paleomagnetic  record of the last million years of climate and oceanographic change in  the New Zealand sector of the South Pacific. (PhD 2011)

Current research

  • Rocks for Tots: engaging  young learners in participatory geoscience research (Curious Minds funded)
  • To better identify magnetic assemblages in the NZ geologic record using first-order reversal curve (FORC) measurements
  • Paleomagnetism and environmental magnetism of piston cores from south western coast of New Zealand

Research interests

My research interests lie in the geological record of  Quaternary climate change and the application  of paleomagnetic methods to dating and correlation and as proxies for  environmental change.
Specifically,

  • Marine records of early Pleistocene terrestrial glaciation.
    • Are Southern Alps events synchronous with Northern Hemisphere (N.H.) glaciations?
    • Is there a hemispheric lead/lag in the onset or termination of glaciations?
    • What is the role of insolation forcing?
  • Last Glacial Maximum (LGM) and deglacial signals in the marine record.
    • Oceanographic or atmospheric linkages between NZ and Antarctica?
    • Is the timing of abrupt climate events synchronous or asynchronous with N.H. events?
  • Developments of techniques that better remove the environmental signal from relative paleointensity records.
  • Hydrodynamic sorting of magnetic minerals; implications for current speed and near-shore paleobathymetry.
  • Magnetic grain-size; comparison of magnetic and other methods of determination, relationship between magnetic grain-size and mean sortable silt/whole sediment distribution.

PhD research

New Zealand and its continental  shelf are situated in a unique position to track changes in the global ocean  and climate system. New Zealand spans the subtropical and subantarctic currents  and intercepts and deflects both westerly winds and the westerly Antarctic Circumpolar  Current (ACC). The ACC influences global ocean circulation and is considered to  be a major climate driver. Furthermore, the New Zealand landmass presently  contributes almost two percent of the global ocean sediment load per year. Rain  and wind erosion (heightened by New Zealand's position as a barrier in the  South Pacific) and tectonics (e.g., uplift caused by collision of the Pacific  and Australian plates) contribute to New Zealand's high sedimentation rates. As  a result, ocean sediment in the New Zealand sector of the South Pacific have  the potential to record very high resolution records of both terrigenous and  marine input that forms a globally relevant, Southern Hemisphere paleoclimate  record.

Long sediment cores were collected  from the banks of submarine Hokitika Canyon off New Zealand's West Coast during  the MD152 MATACORE research cruise (Figures 1 & 2). Three cores (30-45m  long) from the MATACORE cruise form a transect along Hokitika Canyon at various  depths (1000->3000m) and record up to one million years of earth's  geological and climatic history (Figure 3). In addition, shorter cores were  collected during NIWA's West Coast Canyons II cruise. The paleomagnetic  laboratory at Otago is equipped with a high-sensitivity, high-resolution  cryogenic magnetometer suitable for long core samples. During the cruises, I  assisted in collecting u-channel samples from the cores for a range of  paleomagnetic and environmental magnetic analyses, including automated closely  spaced measurements of natural remanent magnetism, alternating field  demagnetisation, anhysteretic remanent magnetism and magnetic susceptibility.  Remanent magnetism can provide a high-resolution (sub-millennial) chronology  for the climate records through the determination of secular variation and  paleointensity changes as well as the application of the more traditional  magnetic polarity reversal stratigraphy.

Magnetic susceptibility (the  magnetisability of a substance) can indicate changing types and concentrations  of magnetic minerals, which in turn indicates the source of the minerals and/or  the type of weathering the minerals underwent. Glacial conditions in the  Southern Alps contributed non-oxidized, physically weathered minerals. Fieldwork  in the Southern Alps aided in identifying the signatures of  terrestrially-derived minerals in the cores.

New Zealand's offshore sediment  record is an ideal matrix for environmental magnetic proxy indicators of  paleoclimate. Magnetic properties of sediment cores can be used to better  understand the dynamics of New Zealand's continental margin (e.g., catchment  and canyon evolution through time) and its record of climate change. Hokitika  Canyon provides an opportunity to understand the continuum of processes that  affect paleomagnetism and environmental magnetism off New Zealand's South  Island West Coast on sub-millennial timescales.

Figure 1: R/V Marion-Dufresne II about to embark on the MD 152/MATACORE -Tectonic and climatic controls on sediment budget- cruise (Hobart, Tasmania – Auckland, NZ) (January 24-February 6, 2006).Figure 1: R/V Marion-Dufresne II about to embark on the MD 152/MATACORE "Tectonic and climatic controls on sediment budget" cruise (Hobart, Tasmania – Auckland, NZ) (January 24-February 6, 2006).

Figure 2: Calypso piston coring system. The lead weight (up to 10 tonnes) drives the core pipe into marine sediment. The longest core recovered on this cruise was over 39 m long (MD06-2987).Figure 2: Calypso piston coring system. The lead weight (up to 10 tonnes) drives the core pipe into marine sediment. The longest core recovered on this cruise was over 39 m long (MD06-2987).

core locationsCore locations

Publications

Ruz Ginouves, J. A., White, J. D. L., Fierstein, J., Ohneiser, C., & Nelson, F. (2023). Heating temperatures of muddy country rock during dike emplacement. In G. E. Frontin-Rollett & S. D. Nodder (Eds.), Geoscience Society of New Zealand Miscellaneous Publication. 164A, (pp. 214). Wellington, New Zealand: Geoscience Society of New Zealand. [Abstract] Conference Contribution - Published proceedings: Abstract

Nelson, F., & Briggs, S. (2023). Tools and techniques for extending geoscience outreach into Early Childhood Education settings. In G. E. Frontin-Rollett & S. D. Nodder (Eds.), Geoscience Society of New Zealand Miscellaneous Publication. 164A, (pp. 172). Wellington, New Zealand: Geoscience Society of New Zealand. [Abstract] Conference Contribution - Published proceedings: Abstract

Briggs, S., & Nelson, F. (2023). Engaging preschool children with geoscience: Challenges and opportunities. In G. E. Frontin-Rollett & S. D. Nodder (Eds.), Geoscience Society of New Zealand Miscellaneous Publication. 164A, (pp. 34). Wellington, New Zealand: Geoscience Society of New Zealand. [Abstract] Conference Contribution - Published proceedings: Abstract

Lurcock, P., Nelson, F., Florindo, F., & Wilson, G. (2019). Enviromagnetism and palaeomagnetism of Holocene sediments from Lake Ohau, New Zealand. Geophysical Research Abstracts, 21, EGU2019-9674. [Abstract] Conference Contribution - Published proceedings: Abstract

Ward, B., Jackson, L., Barendregt, R. W., Huscroft, C., & Nelson, F. (2018). Glacier-volcano interactions provide insight on glacial history and geomorphic evolution, Ft. Selkirk, Yukon Territory, Canada. Geophysical Research Abstracts, 20, EGU2018-18849-2. [Abstract] Conference Contribution - Published proceedings: Abstract

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