Earth's surface transformed by massive asteroids

August 5, 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: 'Bathtub rings' suggest Titan's dynamic seas

Related Stories

'Bathtub rings' suggest Titan's dynamic seas

July 28, 2015

Saturn's moon, Titan, is the only object in the Solar System other than Earth known to have liquid on its surface. While most of the lakes are found around the poles, the dry regions near the equator contain signs of evaporated ...

High-resolution mapping produces ecological data

July 24, 2015

Beyond simple topographic data, high-resolution digital elevation models can provide estimates for a diverse range of ecological variables. But as shown in a recent study, higher resolution models do not always provide more ...

Mounting threat to Galapagos from 'El Nino'

July 23, 2015

The Galapagos Islands, celebrated for their breathtaking biodiversity, could face a major threat from "El Nino," the weather system known to wreak havoc every few years.

Vesta's potassium-to-thorium ratio reveals hot origins

July 23, 2015

Studies of materials on the surface of Vesta offer new evidence that the giant asteroid is the source of howardite, eucrite and diogenite (HED) basaltic meteorites, supporting current models of solar system evolution and ...

Recommended for you

Short wavelength plasmons observed in nanotubes

July 28, 2015

The term "plasmons" might sound like something from the soon-to-be-released new Star Wars movie, but the effects of plasmons have been known about for centuries. Plasmons are collective oscillations of conduction electrons ...

'Expansion entropy': A new litmus test for chaos?

July 28, 2015

Can the flap of a butterfly's wings in Brazil set off a tornado in Texas? This intriguing hypothetical scenario, commonly called "the butterfly effect," has come to embody the popular conception of a chaotic system, in which ...

New chemistry makes strong bonds weak

July 28, 2015

Researchers at Princeton have developed a new chemical reaction that breaks the strongest bond in a molecule instead of the weakest, completely reversing the norm for reactions in which bonds are evenly split to form reactive ...

0 comments

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.