Oblique rifting along the central and southern Kermadec Arc front (30°–36°S), SW Pacific

Campbell, M. Ellen, Rowland, Julie V., Wright, Ian C. and Smith, Ian E. M. (2007) Oblique rifting along the central and southern Kermadec Arc front (30°–36°S), SW Pacific. Geochemistry, Geophysics, Geosystems, 8 (1), Q01007. (doi:10.1029/2006GC001504).

Abstract

We present a series of eleven structural maps of the central Kermadec arc front between 30°S and 35°50S interpreted from multibeam bathymetric data. These maps show the structural morphology of eighteen submarine arc volcanoes proximal to the Havre backarc, providing a critical window into the tectonomagmatic processes that operate at divergent arcs transitional to seafloor spreading. Each arc volcano, unaffected by subaerial processes, shows the structural imprint of oblique backarc rifting, providing an exceptional opportunity to evaluate tectonic influences on edifice construction and destruction. Mapped seafloor structures include faults, volcanic ridges, aligned vents and cones, cones aligned with faults, elongate calderas, and structurally controlled sector collapse. In addition to the structural maps, we present the results of quantitative analyses of fault orientation and growth behaviors. We demonstrate that >50% of identified faults strike NE-SW between 030° and 060°, with a modal value of 047°, evidence in support of an extension axis dextrally oblique to the NNE trend of the rift. Further to this, minimum and maximum values for the extension axis are calculated as 137° and 150°, perpendicular to the modal strikes for all identified faults and for faults within the most oblique surveyed backarc rift domain, respectively. These values confirm moderate obliquity of opening along the Havre rift, with the SHT opening slightly less obliquely than the NHT, consistent with accommodation of a lesser partitioned component of dextral Pacific-Australian plate convergence.

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