Quaternary Sedimentation on the Hikurangi Oblique-Subduction and Transform Margin, New Zealand
- Peter F. Ballance and
- Harold G. Reading
Published Online: 20 APR 2009
Copyright © 1980 The International Association of Sedimentologists
Sedimentation in Oblique-Slip Mobile Zones
How to Cite
Lewis, K. B. (1980) Quaternary Sedimentation on the Hikurangi Oblique-Subduction and Transform Margin, New Zealand, in Sedimentation in Oblique-Slip Mobile Zones (eds P. F. Ballance and H. G. Reading), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303735.ch10
- Published Online: 20 APR 2009
- Published Print: 11 SEP 1980
Print ISBN: 9780632006076
Online ISBN: 9781444303735
- quaternary sedimentation on Hikurangi obliquesubduction and transform margin;
- Hikurangi Margin/Trough system of New Zealand, extension of Tonga-Kermadec Arc/Trench subduction system;
- Tonga-Kermadec subduction system, intersecting subcontinental Hikurangi system;
- Rapid sedimentation, affecting Hikurangi Margin;
- oblique-slip plate boundary, traversing Hikurangi Trough
The Hikurangi Margin/Trough system on the northeastern side of New Zealand is mainly an extension of the Tonga–Kermadec Arc/Trench subduction system into a continental environment. Structural elements become progressively more elevated and subduction progressively more oblique towards the south until the whole system is truncated at a strike-slip, transform boundary that extends along the southwestern part of the Hikurangi Trough and the Hope Fault to the Alpine Fault.
Subduction, combined with rapid detrital sedimentation, has led to the development of a 150 km wide, imbricate-thrust controlled, accretionary borderland of seaward-faulted, anticlinal ridges and landward-tilting basins. The basins are generally 5–30 km wide, 10–60 km long and contain fill 200–2000 m thick. The borderland continues on land where the highest accretionary ridges (normally at mid-bathyal depths) form a line of coastal hills in front of a line of strike-slip faulted, highest accretionary basins and volcano-backed, frontal ranges.
Turbidites, hemipelagic muds and volcanic ash layers fill the tilting slope basins with wedge-shaped layers, at rates ranging from about 0·1 m/1000 years in lower slope basins to about 0·3 m/1000 years in upper slope basins. Prisms of sandy mud build the shelf upwards at maximum rates of 3·0 m/1000 years during interglacial periods of high sea level, and the upper slope upwards and outwards at similar rates during glacially lowered sea level.
On the upper slope, sheets of sediment more than 10 km in length but only a few tens of metres thick have slumped on slopes of as little as 1°, probably after dewatering of surface mud has trapped excess pore water in underlying coarse silty layers.
Along the steep, southwestern transform margin much of the influx of muddy sediment is fed direct to the Hikurangi Trough along canyons.