Complex movement of tectonic plates decoded at the submarine Havre Trough north of New Zealand

The waters of the Pacific are calm on this photo taken from a research vessel, but volcanoes are active at the seafloor of the research area. Photo: Christian Timm, Geomar

Scientists from New Zealand and Germany gather insights into the southwest Pacific submarine volcanism which is part of the ocean’s Ring of Fire

It’s boiling on the southwest Pacific seafloor. The geologically active zone that formed the central portion of the North Island of New Zealand continues for thousands of kilometers offshore to the north. One volcano joins another. This chain is part of a so-called subduction zone, where the westward-moving Pacific Plate dives beneath the Australian Plate. The processes occurring here are complex, because the movement is very slow. For many years scientists have been trying to resolve the geological history of this region. A team of scientists from New Zealand and Germany with participation of the Geomar Helmholtz Centre for Ocean Research Kielnow published their results in a study that appeared in Nature Geoscience.

Schematic diagram of the tectonic processes in three phases: a) up to 5 My, b) between 5 and 2.5 My and c) in the most recent period. Graphics from Tontine et al.

„We investigated the submarine Havre Trough, located between the Colville and Kermadec Ridges north of New Zealand” explains Christian Timm from Geomar, co-author of the study. „In this region, new seafloor began to form 5 Million years ago via subduction of the Pacific Plate at the Kermadec Trench”.

„We know for decades that the Taupō-Volcanic Zone stretches at a rate of few millimeters per year says Dr. Caratori Tontini, main author of the study. „We also know that the Havre Trough is stretching similarly, but failed to understand why the outer boundaries of the Taupo Volcanic Zone did not align with the offshore Colville- and Kermadec Ridges”, continues Tontini.

„Our studies demonstrate that the Havre Trough consists of two separate parts: a now quiet western half and much more active eastern zone, that represent two stages of seafloor formation” explains Dr. Cornel de Ronde from GNS Science, co-author of the study and presently guest scientist at German Geomar institute. „The older western region formed very rapidly similar to how seafloor is generated at the mid-Atlantic ridge. On the contrary, the younger eastern part of the Havre Trough formed much slower allowing the emplacement of the active volcanoes of the Kermadec arc and the Taupō-Volcanic Zone, as we know it today” continuous de Ronde.

The study led by GNS Science in New Zealand used comprehensive geophysical datasets collected with ships, satellites, and planes over 15 years in close collaboration with institutes like Geomar.

Map of the research area north of New Zealand. After Tontine et al.

„With this research, we now understand much better how the unique landscape of New Zealand was shaped and can better predict how this dynamic region this planet will evolve in the future” concludes Dr. Caratori Tontini.

Tontini, F.C., D, Bassett, C.E.J. de Ronde, C. Timm, and R. Wysoczanski, 2019. Early evolution of a young back-arc basin in the Havre Trough. Nature Geoscience,

Source: Geomar

(02.10.2019, USA: 10.02.2019)