[meteorite-list] Iron From Meteorites Helps Probe Early Solar Nebula

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:43:33 2004
Message-ID: <200107201908.MAA27634_at_zagami.jpl.nasa.gov>


Iron From Meteorites Helps Probe Early Solar Nebula
July 19, 2001

Scientists have made a big step towards understanding the chemical state of
the early solar nebula by studying the variation of iron isotopes in samples
from meteorites, Earth and Mars.

Using new state-of-the-art techniques developed in the Isotope Geochemistry
Laboratory at Oxford University's Department of Earth Sciences, they have
discovered that the early solar nebula appear to have been very well mixed
prior to the formation of asteroids and their components, chondrules.

Knowledge about the degree of chemical and isotopic homogeneity of the solar
nebula is a starting point in understanding the chemical evolution of the
early solar system.

This fundamental issue is, however, notoriously difficult to pin down,
because even the most primitive materials in the solar system today have
already undergone chemical evolution.

Scientists at Oxford have now launched a program to study the isotope
variations of transition metals.

Beginning with iron, a major component of solid materials in the solar
system which has four naturally occurring stable isotopes, they have
discovered that, although iron has been formed in different stars with
different proportions of isotopes, it has been very well-mixed prior to
planetary evolution.

This discovery challenges previous arguments about early solar heterogeneity
based on some ambiguous evidence.

Dr. Xiangkun Zhu, who led the research project, said, "This discovery is of
great significance in understanding the solar system evolution. We are now
expanding our study to isotopes of other metals, such as those of titanium
and zinc.

"All together, they are expected to provide significant new insights into
some important processes operating in the early solar nebula, such as
evaporation, condensation and metal-silicate fractionation."

(Reference: The paper "Isotope homogeneity of iron in the early solar
nebula" is published in Nature 19.07.01. The authors are X.K Zhu, Y Guo, R K
O'Nions, E D Young, R D Ash.)
Received on Fri 20 Jul 2001 03:08:49 PM PDT

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