Feeds

Early Earth’s ‘golden shower’

Shiny yellow stuff arrived on meteors

Application security programs and practises

Rocks from Isua in south-west Greenland have been hailed as providing evidence for what geologists believe is the source of complex and heavy elements on Earth: an asteroid shower that endowed our young planet with gold (as well as platinum, iridium, nickel and tungsten).

The research to be published in Nature suggests that the different makeup of rocks from Earth’s mantle of 4.8 billion years ago and 3.8 billion years ago suggests a protracted meteor bombardment sometime around 3.9 billion years ago laced the crust with billions of tons of dead-star residues that we now mine.

The researchers, led by Matthew Willbold of the University of Bristol, sampled rocks from the earliest crust – formed when Earth cooled enough to actually have a solid rather than a liquid surface – and compared these to newer rocks.

In particular, they have identified different concentrations of tungsten in the different ages of rock, which serve as markers of the heavy metal arriving in the long window from 4.8 to 3.8 billion years ago.

If the metals had arrived on a molten planet, they would not have survived to be distributed in the mantle, instead sinking to the core.

Discovery quotes Willbold as saying the rocks provide “a sort of time capsule that gave us the possibility to calculate how much material had to be added to the Earth to satisfy the tungsten isotopic composition that we find in the Earth today.”

Around one-half of one percent of today’s mantle arrived in the form of meteors, he said, which equals about 300 billion billion tons of material.

Damping the excitement with a contrary view, New Scientist notes that there appears to be too little precious metals for the hypothetical bombardment to be a complete explanation. ®

Build a business case: developing custom apps

More from The Register

next story
Asteroid's DINO KILLING SPREE just bad luck – boffins
Sauricide WASN'T inevitable, reckon scientists
BEST BATTERY EVER: All lithium, all the time, plus a dash of carbon nano-stuff
We have found the Holy Grail (of batteries) - boffins
Just TWO climate committee MPs contradict IPCC: The two with SCIENCE degrees
'Greenhouse effect is real, but as for the rest of it ...'
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
Famous 'Dish' radio telescope to be emptied in budget crisis: CSIRO
Radio astronomy suffering to protect Square Kilometre Array
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Securing Web Applications Made Simple and Scalable
Learn how automated security testing can provide a simple and scalable way to protect your web applications.