Vanuatu ' much older ' after recent discovery

Transcript

A groundbreaking discovery in Vanuatu could prove the country is much older than current theories argue.

A student researcher from James Cook University, Janrich Buys, found a fragment of volcanic rock from the 'geological basement' of Vanuatu matching 3 billion-year-old material from Australia, suggesting Vanuatu formed part of the 'supercontinent' Gondwanaland.

The supervising Senior Lecturer, Dr Carl Spandler, told Alex Perrottet the find will change theories about the origins of Vanuatu.

DR CARL SPANDLER: The discovery was actually a bit of a surprise it was not at all what we were expecting. This particular research project started as a student project, with the aim of going to some, the islands of Vanuatu that are not currently volcanically active. They are a little bit older, they were volcanic islands sometime in the past and we wanted to see when they were active and how they developed. So that was really the aim and then to try and put that into some sort of context of the movement of tectonic plates on the earths surface and so really the finding the of the really old material in these rocks was actually completely a surprise. Something we found later when we returned back to Australia.

ALEX PERROTET: The term was given, geological basement of Vanuatu so what's the process in extracting something of that material?

DCS: Yea, so pretty much everywhere on the planet we only see a very small amount of the earth's crust, we are only seeing what is on the surface at the moment so places like Vanuatu the crust is about 30 kilometres thick. Places like New Zealand it would be more like maybe 40 kilometres thick, so the volcanoes that erupt at the surface you see the magma comes out but that's travel through that entire crustal column to get to the surface and as it does that it actually picks up bits and pieces of the material on its transit through the crust and that is actually one of the ways that we can find out what is actually present at depth in these places and a place like Vanuatu where you always assumed that it was always very young stuff that had developed maybe in the space of a few million years which geologically speaking is very young. But we didn't expect to get this very old material being pulled from depth and brought up in these volcanic rocks. And this finding is significant because if there is already old crust that is present at depth within these places then we may be overestimating how fast the earth can grow continental crust. I mean it goes back to when all of these pieces of the continents, where once part of Gondwana the super continent and this is just another piece of that. So this piece that is now beneath Vanuatu probably rifted of from the eastern Australian margin probably over a hundred million years ago. So this is long before their were any volcanoes in Vanuatu such as you see today.

AP: And finally the finding were made by an honors student is that right?

DCS: Yea, that's right so the honours student is a fourth year of a undergraduate degree its a research project that lasts for ten months and he collected the material did all of the lab work here and he was the first one to analyse this very old material and come up with these very old ages which really had our, had us scratching our heads for a little while but he was really the one who found that amazing result and wrote that up as his thesis.