From oblique subduction to intra-continental transpression: Structures of the southern Kermadec-Hikurangi margin from multibeam bathymetry,side-scan sonar and seismic reflection |
| |
| Authors: | Jean-Yves Collot Jean Delteil Keith B Lewis Bryan Davy Geoffroy Lamarche Jean-Christophe Audru Phil Barnes Franck Chanier Eric Chaumillon Serge Lallemand Bernard Mercier de Lepinay Alan Orpin Bernard Pelletier Marc Sosson Bertrand Toussaint Chris Uruski |
| |
| Institution: | (1) ORSTOM, B. P. 48, 06230 Villefranche slmer, France;(2) Institut de Géodynamique, rue Albert Einstein 06560, Valbonne, Nice, France;(3) NIWA, Kilbirnie, P. O. Box 14901, Wellington, New Zealand;(4) IGNS, P. O. Box 1320, Wellington, New Zealand;(5) Laboratoire de Géologie Dynamique, Université des Sciences et Technologies de Lille 1, 59655 Villeneuve d'Asq, France;(6) Laboratoire de Géodynamique sous-marine, B. P. 48, 06230, Villefranche slmer, France;(7) Laboratoire de Géologie Structurale, Université de Montpellier II, Place Eugène Bataillon, 34095 Montpellier, France;(8) Department of Earth Sciences, James Cook University of North Queensland, Q 4811 Townsville, Australia;(9) ORSTOM, B. P. A5, Nouméa, Nouvelle-Calédonie, France |
| |
| Abstract: | The southern Kermadec-Hikurangi convergent margin, east of New Zealand, accommodates the oblique subduction of the oceanic Hikurangi Plateau at rates of 4–5 cm/yr. Swath bathymetry and sidescan data, together with seismic reflection and geopotential data obtained during the GEODYNZ-SUD cruise, showed major changes in tectonic style along the margin. The changes reflect the size and abundance of seamounts on the subducting plateau, the presence and thickness of trench-fill turbidites, and the change to increasing obliquity and intracontinental transpression towards the south. In this paper, we provide evidence that faulting with a significant strike-slip component is widespread along the entire 1000 km margin. Subduction of the northeastern scrap of the Hikurangi Plateau is marked by an offset in the Kermadec Trench and adjacent margin, and by a major NW-trending tear fault in the scarp. To the south, the southern Kermadec Trench is devoid of turbidite fill and the adjacent margin is characterized by an up to 1200 m high scarp that locally separates apparent clockwise rotated blocks on the upper slope from strike-slip faults and mass wasting on the lower slope. The northern Hikurangi Trough has at least 1 km of trench-fill but its adjacent margin is characterized by tectonic erosion. The toe of the margin is indented by 10–25 km for more than 200 km, and this is inferred to be the result of repeated impacts of the large seamounts that are abundant on the northern Hikurangi Plateau. The two most recent impacts have left major indentations in the margin. The central Hikurangi margin is characterized by development of a wide accretionary wedge on the lower slope, and by transpression of presubduction passive margin sediments on the upper slope. Shortening across the wedge together with a component of strike-slip motion on the upper slope supports an interpretation of some strain partitioning. The southern Hikurangi margin is a narrow, mainly compressive belt along a very oblique, apparently locked subduction zone. |
| |
| Keywords: | Oblique subduction strike-slip faults transpressive deformation tectonic erosion tectonic accretion seamount collision multibeam bathymetry |
| 本文献已被 SpringerLink 等数据库收录！ |
|
