1887
Volume 20, Issue 1-2
  • ISSN: 0812-3985
  • E-ISSN: 1834-7533

Abstract

Late Cenozoic deformation along the Australian/Pacific plate boundary is seen in onshore New Zealand as zones characterised by extension- or transcurrent- or contraction-related structures. High-resolution multichannel seismic reflection data were acquired in several of these tectonic zones and successfully reveal the shallow structures within them.

Thirty kilometres of dynamite reflection data in the Rangitaiki Plains, eastern Bay of Plenty, define a series of NE-trending normal faults within this extensional back-arc volcanic region. The data cross surface ruptures activated during the 1987 Edgecumbe earthquake.

In the southern North Island, a 20 km Mini-SosieTM seismic profile details the Quaternary sedimentation history and reveals the structure of the active strike-slip and thrust fault systems that form the western and eastern edges of the Wairarapa basin, respectively. This basin is considered to sit astride the boundary between a zone of distributed strike-slip faults and an active accretionary prism.

In the Nelson area, northwestern South Island, previously unrecognised low-angle thrust faults of Neogene or Quaternary age are seen from Mini-Sosie data to occur at very shallow depths. Crustal shortening here was previously thought to arise from movement on high-angle reverse faults, and the identification of these low-angle faults has prompted a reassessment of that model.

A grid of 18 km of Mini-Sosie seismic data from the central eastern South Island delineates Neogene or Quaternary thrust faults in Cenozoic sediments. The thrusts are interpreted as reactivated Early Eocene normal faults, and the thrust fault geometry is dominated by these older structures.

© 1989 ASEG
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1989-03-01
2026-01-14

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References

  1. Barbier, M. G., Bondon, P., Meilinger, R. and.Viallix, J. R., (1976), ‘Mini-Sosie for Land Seismology’, Geophysical Prospecting, Vol. 24, No. 3, p. 518-527.
  2. Berryman, K., (1984), ‘Late Quaternary Tectonics in New Zealand’, in An Introduction to the Recent Crustal Movements of New Zealand, R. I. Walcott, compiler, The Royal Society of New Zealand Miscellaneous Series No. 7, 108 p.
  3. Cape, C. D., in prep, ‘Geophysical Studies of the Wairarapa Basin, New Zealand’, Research Report, Geophysics Division, DSIR, Wellington, New Zealand.
  4. Cape, C. D., Lamb, S. H., Vella, P., Wells, P. E., and Woodward, D. J., in review, ‘Geological Structure of Wairarapa Valley, New Zealand, from Seismic Reflection Profiling’, submitted to Journal of the Royal Society of New Zealand.
  5. Grapes R. and Wellman, H., (1988), ‘The Wairarapa Fault’, Research School of Earth Sciences, Victoria University of Wellington, Geology Board of Studies Publication No. 4, 55 p.
  6. O’Connor, R. M., in prep., ‘Structure of the Matahina Ignimbrite in the Southern Rangitaiki Plains from Seismic Reflection Profiling’ Research Report, Geophysics Division, DSIR, Wellington, New Zealand.
  7. Ravens, J. M., in review, ‘Seismic Reflection Surveys in the Takaka Valley, Northwest Nelson’, submitted to New Zealand Journal of Geology and Geophysics.
  8. Staff, New Zealand Department of Scientific and Industrial Research, (1987), ‘The March 2,1987, Earthquake Near Edgecumbe, North Island, New Zealand’, Eos, Vol. 68, No. 44, p. 1162-1171.
  9. Stern, T. A., (1986), ‘Geophysical Studies of the Upper Crust Within the Central Volcanic Region, New Zealand’, in. Late Cenozoic Volcanism in New Zealand, I.E.M. Smith, (ed.), Royal Society of New Zealand Bulletin No. 23, p. 92-111.
  10. Stern, T. A., (1987), ‘Asymmetric Back-arc Spreading, Heat Flux and Structure Associated with the Central Volcanic Region of New Zealand’, Earth and Planetary Science Letters Vol. 85, p. 265-276.
  11. Walcott, R. I., (1984), ‘Reconstructions of the New Zealand Region for the Neogene’, Palaeogeography, Palaeoclimatology, Palaeoecology, Vol. 46, p. 217-231.
  12. Wells, P. E., in prep., ‘Late Neogene Vertical Tectonic Movements in Western Wairarapa, New Zealand’, Ph.D. thesis, Victoria University.
  13. Woodward, D. J., (1988), ‘Seismic Reflection Survey of the Rangitaiki Plains, Eastern Bay of Plenty’, Research Report No. 218, Geophysics Division, DSIR, Wellington, New Zealand, 22 p.
  14. Woodward, D. J. (1989), ‘Note: Geological Structure of the Rangitaiki Plains near Edgecumbe, New Zealand, from Seismic Data’ New Zealand Journal of Geology and Geophysics, Vol. 32, p. 15-16.
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  • Article Type: Research Article
Keyword(s): active shallow structures; high-resolution seismic reflection data; mini-Sosle; New Zealand

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