Structure and dynamics of a submarine continent: tectonic-magmatic evolution of the Campbell Plateau (New Zealand) - Report of the RV SONNE cruise SO-169, Projekt CAMP, 17 January to 24 February 2003


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kgohl [ at ] awi-bremerhaven.de

Abstract

The RV Sonne cruise SO-169 of project CAMP took place from 17 Jan. to 24 Feb. 2003 with a geophysical-geological survey and sampling program of the Campbell Plateau and Bounty Trough of the Southern Pacific, southeast of New Zealand. The Campbell Plateau off New Zealand, as part of the greater New Zealand continent called Zealandia, is one of the world's largest submarine plateaus. The relation between magmatic events and tectonic and structural evolution of the Campbell Plateau is one of the significant remaining questions in the framework of reconstructing the evolution of Zealandia and the southwest Pacific region.The leg consisted of the following main work programs:(1) Analysis of the tectonic structure and geodynamic evolution of the Campbell Plateau by means of a deep seismic traverse from the South Island to the centre of the plateau. In addition to acquiring seismic reflection multi-channel data, ocean-bottom seismographs (OBS) were deployed and provided detailed wavefield information about the seismic velocity distribution and physical properties of the crust and upper mantle. By integrating the seismic data with simultaneously recorded gravity and magnetic records and with petrological information from basaltic dredge samples, a structural-dynamic model of the plateaus evolution will be developed.(2) Understanding the break-up process of Campbell Plateau from Marie Byrd Land, West Antarctica: A seismic refraction OBS profile and reflection profiling across two segments of the Bounty Trough provide evidence for the structural characteristics of the trough and the influence of magmatic phases on the extensional and break-up processes along the plateau margin. A first analysis of the data indicates that initial rifting between New Zealand and Antarctica occurred along the Bounty Trough.(3) Volcanological, geochemical and geochronological studies of magmatic rocks dredged from the Campbell Plateau will contribute to an improved understanding of the geodynamic processes during the break-up of the continents. The sample analyses will contribute to the question whether the Cenozoic volcanism of the plateau results from an asthenospheric upwelling or a swarm of episodic plumes. They also might reveal the existence of a fossil plume head underneath the New Zealand micro-continent.In total, 1284 km of seismic reflection data, 818 km of seismic refraction data (with 45 OBS and 7 land stations), and about 10,000 km of gravity, magnetic, swath-bathymetric and sub-bottom profiler data were collected during this leg. In addition, 16 successful petrological dredge operations were undertaken.



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Eprint ID
9050
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Gohl, K. (2003): Structure and dynamics of a submarine continent: tectonic-magmatic evolution of the Campbell Plateau (New Zealand) - Report of the RV SONNE cruise SO-169, Projekt CAMP, 17 January to 24 February 2003 , Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschungpp. (Berichte zur Polar- und Meeresforschung ; 457), 88 .


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