Earth's surface transformed by massive asteroids

Aug 05, 2005

A cluster of at least three asteroids between 20 and 50 kilometres across colliding with Earth over 3.2 billion years ago caused a massive change in the structure and composition of the earth’s surface, according to new research by ANU earth scientists.

According to Dr Andrew Glikson and Mr John Vickers from the Department of Earth and Marine Sciences at ANU, the impact of these asteroids triggered major earthquakes, faulting, volcanic eruption and deep-seated magmatic activity and interrupted the evolution of parts of the Earth’s crust.

The research extends the original discovery of extraterrestrial impact deposits, discovered in South Africa by two US scientists, D.R. Lowe and G.R. Byerly, identifying their effects in the Pilbara region in Western Australia.

“Our findings are further evidence that the seismic aftershocks of these massive impacts resulted in the abrupt termination of an over 300 million years-long evolutionary stage dominated by basaltic volcanic activity and protracted accretion of granitic plutons,” Dr Glikson said.

The identification of impact ejecta — materials ejected by the hitting asteroid — is based on unique minerals and chemical and isotopic compositions indicative of extraterrestrial origin, including iridium anomalies.

The impact ejecta from the Barberton region in the eastern Transvaal indicate the formation of impact craters several hundred kilometres in diameter in oceanic regions of the earth, analogous to the lunar maria basins (large dark impressions on the surface of the moon). The seismic effects of the impacts included vertical block movements, exposure of deep-seated granites and onset of continental conditions on parts of the earth surface.

In the Pilbara, the formation of fault escarpments and fault troughs is represented by collapse of blocks up to 250-metres wide and 150-metres high, buried canyons and a major volcanic episode 3240 million years ago.

“The precise coincidence of the faulting and igneous activity with the impact deposits, coupled with the sharp break between basaltic crust and continental formations, throws a new light on the role of asteroid impacts in terrestrial evolution,” Dr Glikson said.

Preliminary indications suggest that at about the same time the Moon was also affected by asteroid impacts and by resurgent volcanic activity.

Dr Glikson and Mr Vickers will continue to investigate the extent and effects of large asteroid impacts by studying early terrains in other parts of the world, including India and Canada.

Source: ANU

Explore further: We're not alone—but the universe may be less crowded than we think

Related Stories

Helping Europe prepare for asteroid risk

15 hours ago

Each year, astronomers worldwide discover over 1000 new asteroids or other space rocks that could strike our planet. And if one is spotted heading towards Earth, experts working in ESA and national emergency ...

Rosetta spacecraft sees sinkholes on comet

8 hours ago

The European Space Agency's Rosetta spacecraft first began orbiting comet 67P/Churyumov-Gerasimenko in August 2014. Almost immediately, scientists began to wonder about several surprisingly deep, almost perfectly ...

Early Titan was a cold, hostile place for life

Jun 30, 2015

Titan is a mysterious orange-socked moon of Saturn that is exciting to astrobiologists because it has some of the same kinds of chemicals that were precursors to life on Earth. It also has a hydrological ...

Scientists recruit public to help study "The Blob"

Jun 30, 2015

A huge mass of unusually warm water that scientists have dubbed "The Blob" has lurked off the West Coast for much of the past two years and speculation is growing that it may be connected in some way with the drought plaguing ...

Recommended for you

Observing the birth of a planet

10 hours ago

Astronomers at ETH Zurich have confirmed the existence of a young giant gas planet still embedded in the midst of the disk of gas and dust surrounding its parent star. For the first time, scientists are able ...

Me and my world: The human factor in space

11 hours ago

The world around us is defined by how we interact with it. But what if our world was out of this world? As part of NASA's One-Year Mission, researchers are studying how astronauts interact with the "world" ...

Radar guards against space debris

12 hours ago

Space debris poses a growing threat to satellites and other spacecraft, which could be damaged in the event of a collision. A new German space surveillance system, schedu- led to go into operation in 2018, will help to prevent ...

Why we need to keep adding leap seconds

14 hours ago

Today at precisely 10am Australian Eastern Standard time, something chronologically peculiar will take place: there'll be an extra second between 09:59:59 and 10:00:00.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.