Submarine hydrothermal venting on the southern Kermadec volcanic arc front (offshore New Zealand): location and extent of particle plume signatures
E. T. Baker, R. A. Feely, C. E. J. De Ronde, G. J. Massoth, I. C. Wright, 2003. "Submarine hydrothermal venting on the southern Kermadec volcanic arc front (offshore New Zealand): location and extent of particle plume signatures", Intra-Oceanic Subduction Systems: Tectonic and Magmatic Processes, R. D. Larter, P. T. Leat
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Hydrothermal activity on submarine volcanic arcs in the western Pacific Ocean is known but mostly unexplored. In March 1999, the New Zealand American PLUme Mapping Expedition (NZAPLUME) cruise conducted the first systematic exploration of hydrothermal venting along a sizeable section of an intra-oceanic arc, visiting 13 volcanoes along 260 km of the southern Kermadec arc, just northeast of New Zealand. Conclusive evidence of hydrothermal plumes exists for seven of the 13 volcanoes; at two other volcanoes plume indications were weak and uncertain. The hydrothermal origin of the particle plumes was confirmed by positive anomalies in the ratios of sulphur, iron and copper to titanium relative to non-plume particles, in mass concentrations similar to particles collected from hydrothermal plumes over mid-ocean ridges. The spatial density of active sites along the southern Kermadec arc is at least 2.7 per 100 km (2.7/100 km), probably not significantly different from the weakly constrained value of c. 1/100 km on slow- and intermediate-rate mid-ocean ridges. An analysis of the number of hydrothermal fields produced for the magma delivery rate in each of these environments suggests that the southern Kermadec arc presently has relatively abundant hydrothermal activity. While this result cannot yet be generalized to other Pacific arcs, submarine volcanoes may contribute significantly to the global hydrothermal budget.
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Intra-Oceanic Subduction Systems: Tectonic and Magmatic Processes
Recycling of oceanic plate back into the Earth’s interior at subduction zones is one of the key processes in Earth evolution. Volcanic arcs, which form above subduction zones, are the most visible manifestations of plate tectonics, the convection mechanism by which the Earth loses excess heat They are probably also the main location where new continental crust is formed, the so-called ‘subduction factory’. About 40% modern subduction zones on Earth are intra-oceanic. These subduction systems are generally simpler than those at continental margins as they commonly have a shorter history of subduction and their magmas are not contaminated by ancient sialic crust. They are therefore the optimum locations for studies of mantle processes and magmatic addition to the crust in subduction zones.
This volume contains a collection of papers that exploit the relative simplicity of intra-oceanic subduction systems to provide insights into the tectonic, magmatic and hydrothermal processes associated with subduction.