New Zealand Journal of Geology & Geophysics abstracts

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Olistostromes marking tectonic events, East Coast, New Zealand

J. Delteil¹
B. Mercier de Lepinay¹
H. E. G. Morgans²
B. D. Field^2*

¹Geosciences Azur
UMR 6526
Universite de Nice - Sophia Antipolis
250 Rue Albert Einstein, Sophia Antipolis
F-06560 Valbonne, France

²GNS Science
PO Box 30368
Lower Hutt 5040, New Zealand

^*Corresponding author: brad.field@gns.cri.nz

Abstract   Three discrete, successive tectonic events are marked by olistostromes in the East Coast, North Island. An Eocene Mataikona event is characterised by in situ dismembered beds. A second, Owahanga event is Otaian and preceded wrench faulting coeval with the start of oblique subduction at the East Coast margin. This second event is characterised by extended emplacement of exotic material followed by gliding, gravity-driven nappes that are probably related to obduction along the north coast of the North Island. The third olistostrome is attributed to an early Miocene Mara event synchronous with incipient strike-slip faulting during Altonian times and the commencement of oblique convergence at the Hikurangi margin. From the ages and paleoenvironments of the olistostromes, we propose the Eocene and earliest Miocene syn-sedimentary structures were dragged along the deforming backstop of the Hikurangi prism.

Keywords   melanges; olistostromes; Cenozoic; oblique convergence; deforming backstop

 
G06013; Online publication date 4 December 2006; Received 12 June 2006; accepted 28 November 2006

New Zealand Journal of Geology & Geophysics, 2006, Vol. 49: 517–531
0028–8306/06/4904–0517    © The Royal Society of New Zealand 2006

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