[meteorite-list] Melting Asteroids and the Building Blocks of Early Earth

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Aug 24 12:28:48 2005
Message-ID: <200508241611.j7OGBSv05174_at_zagami.jpl.nasa.gov>

Media Relations Office
Communications Group
The Open University
Milton Keynes, U.K.

Media contact:
Louis De La For?t, +(44) 1908 653256

Academic contact:
Dr Richard Greenwood, +(44) 1908 654107
Dr Ian Franchi, +(44) 1908 655173

EMBARGO 1800 BST 15 June 2005

Melting asteroids and the building blocks of early Earth

Important new research documenting how the Earth formed from melted
asteroids 4.5 billion years ago is published in the 16 June issue of
Nature. The paper was written by Dr Richard Greenwood and Dr Ian Franchi
of the Open University's Planetary and Space Sciences Research Institute
(PSSRI).

"This research is important, Dr Greenwood says, "because it demonstrates
that events and processes on asteroids during the birth of the Solar
System determined the present-day composition of our Earth."

Immediately following the formation of our Solar System 4.5 billion years
ago, small planetary bodies formed, with some melting to produce volcanic
and related rocks. The OU researchers analysed meteorites to see how
processes on asteroids may have contributed to the formation of Earth.

In their paper "Widespread magma oceans on asteroidal bodies in the early
Solar System" Drs Greenwood and Franchi show that some asteroids
experienced large-scale melting, with the formation of deep magma oceans.
Such melted asteroids would have become layered with lighter rock forming
near the surface, while denser rocks were deeper in the interior. Since
large bodies, such as Earth, grew by incorporation of many such smaller
bodies these important results shed new light on the processes involved in
building planets.

The researchers suggest that in the chaotic, impact-rich environment of
the early Solar System, significant amounts of the outer layers of these
melted asteroids would have been removed prior to becoming part of the
growing Earth. This process is a better explanation for the composition of
the Earth than earlier theories which called for large amounts of light
elements in the Earth's dense core, or unknown precursor materials. The
Open University researchers point to recent astronomical observations
which show that these processes are also important in other planetary
systems, such as that around the star Beta Pictoris.

Resources

* http://www.nature.com/nature/journal/v435/n7043/index.html
* http://cepsar.open.ac.uk/index.htm
Received on Wed 24 Aug 2005 12:11:23 PM PDT