Asteroid and comet impacts led to primitive life

April 19, 2006

Australian National University scientists have observed a link between asteroid and comet bombardment of the Earth and the emergence of primitive bacterial life forms in the ancient oceans billions of years ago.

Studying ancient iron-rich sediments in Western Australia and South Africa, Dr Andrew Glikson and colleague Mr John Vickers, from the Department of Earth and Marine Sciences at ANU discovered that the formation of banded iron formations, jasper and iron-rich shale coincided closely with asteroid and comet impacts.

The impacts of the asteroids and comets caused volcanic and hydrothermal activity including eruption of iron-rich basalt, according to Dr Glickson. This created an environment which suited primitive bacteria that lived on the floor of the early oceans, and which derived their energy by oxidising water-soluble (ferrous) iron into insoluble (ferric) iron.

This bacterial activity is thought to have precipitated iron and silica-rich sediments, known as banded iron formations, in areas such as the Pilbara in Western Australia. These banded iron formations host the huge Hamersley and Yarrie iron ore deposits of the Pilbara region.

Dr Glikson made the link when studying whether extraterrestrial impacts could be one of the underlying factors in the appearance of these banded iron formations, spanning ages of 3.5 to 2.4 billion years, which extend over distances of hundreds of kilometres in Western Australia, South Africa, Brazil and Canada.

He found that deposition of iron-rich sediments closely followed massive collisions between asteroids and the Earth at several points in Earth history, including at 3.47, 3.26, 3.24 and 2.63 billion years ago.

“In the majority of cases, the ejected materials left behind from the impact of the asteroids and comets are directly overlain by iron-rich sediments, suggesting a possible cause and effect link between the large impacts, iron-rich volcanic activity and microbial oxidation of iron,” Dr Glikson said.

“It is likely that the asteroid impacts could have triggered faulting, uplift and erosion of iron-rich submarine volcanics.

“The oldest known banded iron formations occur in south-western Greenland, where they are dated as 3.85 billion years old. The age of these banded iron formations coincides with a period of heavy asteroid bombardment on the moon and on Earth, thus marking the earliest known impacts, volcanism and the emergence of microbial colonies at the sea floor,” Dr Glikson said.

To test the significance of these relationships, the scientists are searching for further evidence of asteroid impact units beneath banded iron formations in the Pilbara region of Western Australia.

Source: Australian National University

3.9 /5 (29 votes)  

Rank 3.9 /5 (29 votes)
Tags

Relevant PhysicsForums posts

More news stories

Europe stakes billion-dollar bet on new rocket

A pencil-slim rocket is scheduled to lift into space from South America on Monday, carrying a billion-dollar bet that Europe can grab a juicy slice of the market to place satellites in low orbit.

Space & Earth / Space Exploration

created 18 hours ago | popularity 3.5 / 5 (2) | comments 0

Political leaders play key role in how worried Americans are by climate change: study

More than extreme weather events and the work of scientists, it is national political leaders who influence how much Americans worry about the threat of climate change, new research finds.

Space & Earth / Environment

created Feb 06, 2012 | popularity 5 / 5 (6) | comments 72

NASA budget will axe Mars deal with Europe: scientists

US President Barack Obama's budget proposal to be submitted next week for 2013 will cut NASA's budget by 20 percent and eliminate a major partnership with Europe on Mars exploration, scientists said Thursday.

Space & Earth / Space Exploration

created Feb 10, 2012 | popularity 5 / 5 (3) | comments 48

Humans may have helped the decline of African rainforests 3000 years ago

(PhysOrg.com) -- Large areas of rainforests in Central Africa mysteriously disappeared over three thousand years ago, to be replaced by savannas. The prevailing theory has been that the cause was a change ...

Space & Earth / Environment

created Feb 10, 2012 | popularity 4.1 / 5 (14) | comments 20 | with audio podcast report

High planetary tilt lowers odds for life?

Highly-tilted worlds would have extreme seasons, subjecting life to alternating periods of scorching and subzero temperatures. This could make the development of all but hardiest, simplest creatures a long ...

Space & Earth / Space Exploration

created Feb 06, 2012 | popularity 4.8 / 5 (12) | comments 14 | with audio podcast


Walney offshore wind farm is world's biggest (for now)

(PhysOrg.com) -- The Walney wind farm on the Irish Sea--characterized by high tides, waves and windy weather--officially opened this week. The farm is treated in the press as a very big deal as the Walney ...

GPS court ruling leaves US phone tracking unclear

A US Supreme Court decision requiring a warrant to place a GPS device on the car of a criminal suspect leaves unresolved the bigger issue of police tracking using mobile phones, legal experts say.

Europeans protest controversial Internet pact

Tens of thousands of people marched in protests in more than a dozen European cities Saturday against a controversial anti-online piracy pact that critics say could curtail Internet freedom.

Study finds that anti-diabetic medication can prevent the long-term effects of maternal obesity

In a study to be presented today at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting, in Dallas, Texas, researchers will report findings that show that short therapy with the anti-diabetic medication ...

Netflix settlement trims 14 pct off 4Q earnings

(AP) -- Netflix pressed the rewind button on its fourth-quarter earnings after settling allegations that the video subscription service violated a consumer-privacy law.

Navy to begin tests on electromagnetic railgun prototype launcher

The Office of Naval Research (ONR)'s Electromagnetic (EM) Railgun program will take an important step forward in the coming weeks when the first industry railgun prototype launcher is tested at a facility ...