Tag Archives: curtin

Measuring change

Using a combination of satellite data and ground observations, spatial scientists are able to measure water use, land changes and climate variability with greater accuracy than ever before. Professor of Geodesy Will Featherstone at Curtin is measuring the rate at which land in Perth is sinking due to water drawn from the city’s underground aquifers.

“As the water gets pulled out, the weight of the rocks on top causes the land to subside,” he says. “We’re using satellite techniques, GPS, plus a radar technique called InSAR, where we take a radar picture of Perth every 11 days. We stack all these images together to deduce the subsidence.”

The study is also being used to correct records of sea level rise in Perth, which have been exaggerated in some places because of the sinking land. The team is also working further afield, using precision satellite measurement techniques to stave off conflict over water distribution in Northeast Africa.

Using data from the Gravity Recovery and Climate Experiment (GRACE) satellites, spatial scientist Associate Professor Joseph Awange has been able to show that between 2002 and 2011, Egypt over-extracted water from the Nile Basin for irrigation purposes.

The satellite data also showed a sharp drop in rainfall across the region in November and December 2010 and a decline in rainfall over the 10-year study period in the Ethopian Highlands.

Awange says measuring water use in the Nile Basin can determine if countries are abiding by the 1929 Nile Water Agreement to share the world’s longest river.

Analysing satellite data could show which countries are over-extracting water from the Nile. “If the upstream countries use a lot of the water, then the chance is that the downstream countries such as Egypt will not have enough to sustain them,” says Awange.

“Egypt has threatened several times that they’re ready to go to war if the upstream countries extract more than is necessary,” he says.

Michelle Wheeler

Molecular detective studies mass extinction events

When the Earth warmed and the oceans turned toxic with hydrogen sulfide about 250 million years ago, up to 95% of marine life and 70% of terrestrial species were wiped out – the largest of five mass extinction events in Earth’s history. Much of what we know about these is thanks to research by John Curtin Distinguished Professor Kliti Grice – organic and isotope geochemist and founder of Curtin’s WA-Organic and Isotope Geochemistry Centre within the Institute for Geoscience Research and the John De Laeter Centre for Isotope Research. Grice studies the molecular signatures of chemicals that have been made by micro-organisms, plants and animals, and deposited in lakes and oceans, thousands or even hundreds of millions of years ago.

Her work requires a deep knowledge of biochemical pathways, geology, chemistry, ecology, stable isotopes within organic molecules, and cutting edge analytical techniques in order to interpret clues left behind in rocks and determine which organisms lived in certain aquatic regions and when.

“I look at everything from about 2.3 billion years ago, through to the present day, including recovery after the mass extinction events,” she says. “Most people know about the dinosaur mass extinction, which was unique because it was due to a meteorite impact,” she says. But the other mass extinctions were caused by changes in the atmosphere and oceans.

Grice is working on the Triassic-Jurassic extinction, which occurred about 200 million years ago when supercontinent Pangaea began to break up. “There was a lot of carbon dioxide and flood basalts from volcanic eruptions. We established that the same conditions existed in the oceans then as they did in the largest mass extinction event 50 million years earlier,” she says. These events were biochemically driven, with environmental events leading to high carbon dioxide and hydrogen sulfide in bodies of water.

Grice’s research is also relevant to petroleum and mineral exploration, as well as to modern day climate and environmental changes. “We work with people across disciplines including geologists, engineers, mathematicians, biologists and geographers,” she says.

Grice is passionate about working with PhD students and early and mid-career scientists and helping them develop. “I like sharing my enthusiasm and ideas – seeing young scientists grow, helping them with their research and providing opportunities, including visits to different parts of the globe.”

Michelle Wheeler

Out of this world

The secrets of Earth, the Moon and Mars are being uncovered by detailed studies of zircon crystals in ancient rocks.

John Curtin Distinguished Professor Simon Wilde and Associate Professor Alexander Nemchin, with colleagues from Curtin’s Department of Applied Geology, undertake in situ isotopic analyses of zircons and other chemically complex materials.

To do this they use Curtin’s two Sensitive High Resolution Ion Micro Probes (SHRIMPs) in the John De Laeter Centre for Isotope Research.

“The oldest zircons on Earth, the Moon and Mars – which are all close to 4.4 billion years old – have been dated using the Curtin SHRIMPs,” says SHRIMP Manager Dr Allen Kennedy.

While Wilde primarily focuses on terrestrial zircons, Nemchin – who divides his time between Curtin and the Swedish Museum of Natural History in Stockholm – has analysed zircons from the Moon and Mars.

“Previous research in the seventies discovered abundant zircon in many lunar samples delivered by the Apollo missions,” Nemchin says. “So we used zircon samples from the Moon to gain a better understanding of how to interpret our terrestrial zircon data.”

The results were illuminating: “We found the currently oldest known zircon on the Moon with an age of 4.417 billion years
– which provides the youngest limit to the formation of the lunar magma ocean.” This vast ‘ocean’ of partially melted rock
is thought to have swamped the Moon shortly after it formed.

In addition, Nemchin and his international collaborators, including NASA, identified a series of features in zircon grains that allow major lunar impact events to be dated.

They have also developed novel methods of analysing phosphates from the Moon with a precision close to a few million years. “Together, this resulted in our questioning of the terminal lunar cataclysm hypothesis.”

Out of this world embed 300
Zircon research by a team at the John De Laeter Centre for Isotope Research found that dramatic changes on Mars 1.7 billion years ago resulted in its barren landscape today.

Also known as the Late Heavy Bombardment, the lunar cataclysm concept was put forward in the 1970s. It suggests that asteroids barraged the Moon for a short time approximately 3.9 billion
years ago, causing much of the cratering seen today on the lunar surface and having geological consequences for Earth.

Nemchin’s results instead suggest multiple cataclysmic spikes of impacts occurred throughout the history of the Solar System, separated by relatively quiet periods.

The team also dated zircon found in an ancient Martian meteorite known as Black Beauty, which was discovered in the Sahara Desert in 2011 by Bedouin tribesmen.

After they determined that the meteorite’s zircon crystals were 4.43 billion years old, the team took precise measurements that provided additional ideas about how the Martian atmosphere has changed through time.

They found that water on Mars was more abundant when the crystals formed, but something dramatically changed prior to 1.7 billion years ago, leaving the barren Martian desert that persists to this day.

– Ben Skuse