Visiting a subduction zone in New Zealand

September 29th, 2010

CHRISTCHURCH, NEW ZEALAND–Wooster geology student Andrew Collins has once again visited a fascinating geological locality in New Zealand. He is certainly getting his semester’s worth of adventures, from earthquakes to glaciers. Please visit his blog and see additional photos and descriptions of his trips.

Kaikoura Canyon and associated peninsula and mountains. From: http://www.janesoceania.com/newzealand_kaikoura/index.htm

This time Andrew came about as close to the trench of a subduction zone as is possible without getting wet. He journeyed to Kaikoura on the South Island north of his university base at Christchurch. This town is at the base of a peninsula and squeezed between mountains and the coast. Just a few hundred meters offshore is a deep trough (Kaikoura Canyon) marking a trench where part of the Pacific Plate is being subducted beneath New Zealand, producing volcanoes. The trough also forms an oceanic upwelling system that nourishes phytoplankton which in turn are the primary producers for a diverse and abundant community of organisms culminating with seals and whales. Geologists love to visit active places like this — but we don’t buy real estate there!

Andrew noted the uplifted limestones along the peninsula. These are Late Cretaceous in age, adding to the Cretaceous theme in this year’s blog entries. (Click “Cretaceous” in the tag cloud to the right and see.)

Upifted Upper Cretaceous limestones along the Kaikoura coast, New Zealand. Photo by Andrew Collins.

Tectonic fabric exposed in Upper Cretaceous limestones along the Kaikoura coast, New Zealand. Photo by Andrew Collins.

The Southern Alps, surf and a gravelly beach near Kaikoura, New Zealand. Note the low beach ridges formed by storm waves. Photo by Andrew Collins.

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