Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: thedoc on 08/09/2011 17:39:29

Title: How did Earth get its gold?
Post by: thedoc on 08/09/2011 17:39:29

Gold, platinum and many other precious metals are more common in the Earth's crust than models of the planet's formation would predict, causing some to question the current theory. But now it looks like the planet's surface was re-endowed with "bling" by a late meteor shower...

Read the whole story on our  website by clicking here (http://www.thenakedscientists.com/HTML/content/news-archive/news/2372/)

  

Title: How did Earth get its gold?
Post by: CliffordK on 08/09/2011 20:44:57

Has there been a significant amount of gold found in regolith or moon rock?

Meteorites, of course, get concentrated with heavy metals due to their shedding the lighter materials in the upper atmosphere, which presumably comes down much more diffusely.

Gold is often found in veins from igneous processes, and wouldn't seem to require delivery by asteroids, but rather requires volcanic and seismic activity to bring it to the surface.

Is this early asteroid bombardment a late extension of the planet formation?

Title: How did Earth get its gold?
Post by: Mazurka on 09/09/2011 11:58:07

This theory has been around since the 70's - logic dictates that heavy elements present such as gold when the earth accreted would have ended up in the core. 

The various processes whereby gold gets concentrated into veins etc are not thought to go as deep as the core.

The late heavy bombardment event occurred when the development of the core/ mantle was nearly (if not totally) complete.

The isotopic geochemistry of tungstun (gold inconvieniently lacking isotopes) shows a difference between before and after the late heavy bombardment.

Title: How did Earth get its gold?
Post by: Don_1 on 04/10/2011 13:34:49

I hope Gordon Brown doesn't read this! He'll flog it on www.ebay.mars for a couple of dollars an ounce.