Chronology of Christmas Island's volcanic history unearthed

May 27, 2014 by Kerry Faulkner
Researchers established the age of the various rocks on Christmas Island at the time they were erupted, and established the position of the island through time. Credit: Peter McKiernan

Geological samples from Christmas Island have been analysed by a West Australian scientist, giving valuable insight into its unique volcanic history.

Curtin University geochronologist Dr Fred Jourdan says while continents are often the subject of geological investigation, ocean geology is less studied and the results of the Christmas Island study adds important information to the field.

The report he co-authored has been published in Gondwana Research.

It describes the Christmas Island area as an extensive zone of volcanism in the north-east Indian Ocean, consisting of numerous submerged seamounts and flat topped guyots.

It explains the island has experienced multiple episodes of volcanism that are exposed sporadically along its coastline.

It is the only island in the region to show intraplate volcanism in the form of basaltic rocks that are exposed above sea level.

Dr Jourdan says the project was a collaboration with Macquarie University. Samples were collected by a student from Macquarie University and tested at Curtin University using 40Ar/39Ar geochronology and paleomagnetism.

Dr Jourdan says this is where the 'real science' of finding their origin began.

"What we did was two things; we established the age of the various rocks on the island at the time they were erupted, and we established the position of the island through time," he says.

"We needed to look at where it was before, to understand why there is activity at all—is it random or related to something in particular?

"We measured two different ages but we know, comparing it to other seamounts, there are in fact three periods of volcanic activity.

Three stages of Christmas Island volcanic activity

"The oldest happened when Australia and India separated and the rock left behind melted to create a seamount—that was the first , although we didn't sample this and at this time, the island was much further south than it is now.

"The second, happened between 43 and 37 million years ago—it happened when the continent moved north above a hot zone in the mantle.

"Nothing happened for 30 million years until, in its northward movement toward the European-Asian plate; the plate cracked five million years ago and the magma could easily rise through the cracks."

Dr Jourdan says similar low volume intraplate volcanism had previously been observed at similar tectonic settings to the Japan and Tonga trench.

"…We put forward the Indo Australian plate subduction setting as a likely candidate for this phase of introceanic volcanism."

Explore further: Shattering past of the 'island of glass'

More information: Rajat Taneja, Craig O'Neill, Mark Lackie, Tracy Rushmer, Phil Schmidt, Fred Jourdan, "40Ar/39Ar geochronology and the paleoposition of Christmas Island (Australia), Northeast Indian Ocean," Gondwana Research, Available online 27 April 2014, ISSN 1342-937X, dx.doi.org/10.1016/j.gr.2014.04.004.

add to favorites email to friend print save as pdf

Related Stories

Studying ancient Earth's geochemistry

Jan 18, 2013

Researchers still have much to learn about the volcanism that shaped our planet's early history. New evidence from a team led by Carnegie's Frances Jenner demonstrates that some of the tectonic processes driving volcanic ...

Shattering past of the 'island of glass'

May 21, 2014

A tiny Mediterranean island visited by the likes of Madonna, Sting, Julia Roberts and Sharon Stone is now the focus of a ground-breaking study by University of Leicester geologists.

Seismic activity felt on Spanish volcanic island

Dec 23, 2013

Spain's National Geographical Institute says the Canary Island of El Hierro has been rocked by more than 50 tremors in 24 hours, two years after a new volcano began to appear off its southern coast.

Recommended for you

Asian monsoon much older than previously thought

11 hours ago

The Asian monsoon already existed 40 million years ago during a period of high atmospheric carbon dioxide and warmer temperatures, reports an international research team led by a University of Arizona geoscientist.

Rules of thumb for climate change turned upside down

11 hours ago

With a new analysis of land regions, ETH climate researcher are challenging the general climate change paradigm that dry regions are getting drier and wet regions are getting wetter. In some regions they ...

Tropical Storm Odile taken on by two NASA satellites

Sep 12, 2014

As Tropical Storm Odile continues to affect Mexico's west coast and stir up dangerous surf, NASA's TRMM and Aqua satellites provided forecasters information on clouds and rainfall in the coast-hugging storm. ...

User comments : 0