Qingzhu Yin talks with
ScienceWatch.com and answers a few questions about
this month's New Hot Paper in the field of Geosciences.
Article Title: Al-26-Mg-26 and Pb-207-Pb-206
systematics of Allende CAIs: Canonical solar initial
Al-26/Al-27 ratio reinstated
Authors: Jacobsen, B;Yin, QZ;Moynier,
F;Amelin, Y;Krot, AN;Nagashima, K;Hutcheon, ID;Palme, H
Journal: EARTH PLANET SCI LETT, Volume: 272, Issue: 1-2, Page:
353-364, Year: JUL 30 2008
* Univ Calif Davis, Dept Geol, Davis, CA 95616 USA.
* Univ Calif Davis, Dept Geol, Davis, CA 95616 USA.
* Geol Survey Canada, Ottawa, ON K1A 0E8, Canada. (addresses have been
truncated.)
Why do you think your paper is highly
cited?
The existence of the short-lived radioactive nuclide 26Al
(half-life 0.73 million years, Myr) at the beginning of the solar system
4.567 billion years (Gyr) ago, has been known since the mid-1970s.
Recently, the amount of radioactive 26Al relative to the stable
27Al in the early solar system was revised upwards by about 10%
or more, as described in papers that appeared in the prominent journals
like Science (2005) and Nature (2004, 2005),
respectively. Our paper shows that this upward revision is not warranted.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
"I consider isotopes to be the "DNA" of physical
science. Natural abundance variation of isotopes will
continue to serve us well, as these are the most important
tracers of physicochemical processes which exist in
nature."
Our paper described the most detailed investigation, using modern
technology, of the initial inventory of 26Al in the oldest
object in the solar system, a solid material called Ca-Al-rich inclusions
in the "Allende" meteorite, one of the most primitive meteorites known as
carbonaceous chondrites ever found on Earth.
These carbonaceous chondrites are cosmic sediments, which witnessed the
birth of our solar system. They remained intact in the cold storage of
asteroid belts for the past 4.567 Gyr, and then were delivered to Earth by
natural forces in 1969 to Allende, Mexico, in a "free sample return" as
meteorites, in the same year when the Apollo program astronauts returned to
Earth with the first lunar samples.
Would you summarize the significance of your paper
in layman's terms?
A precise knowledge of the initial inventory of radioactive nuclides, such
as 26Al, at the beginning of the solar system provides crucial
pieces of information for the time zero age-anchor and the initial heat
budgets from radioactivities for early planetary differentiation and
evolution.
It also provides important information about the environment in which our
solar system was born 4.567 Gyr ago. The paper describes the very first
solid object in our solar system, which was precisely dated with an
uncertainty of 20 Kyr. On a human scale, this is equivalent to uncovering a
memory of the first 1.7 hours of birth for a 45-year-old person.
How did you become involved in this research, and
were there any problems along the way?
Like many discoveries in science, I got involved in this research
serendipitously. I gave my student (the first author Benjamin Jacobsen) a
project to develop Mg chemical separation procedures for other
applications.
Purely as a way of self-consistency to check whether the protocols
developed by us work properly or not, I gave the meteoritic materials to
the student to reproduce the literature value, as outlined in the most
recent Science and Nature results. To our surprise, the
more we worked on the material, the more we became convinced that there was
nothing wrong with our own procedures.
Where do you see your research leading in the
future?
I consider isotopes to be the "DNA" of physical science. Natural abundance
variation of isotopes will continue to serve us well, as these are the most
important tracers of physicochemical processes which exist in nature.
Qing-zhu Yin, Ph.D.
Professor
Department of Geology
University of California, Davis
Davis, CA Web
KEYWORDS: EARLY SOLAR SYSTEM CHRONOLOGY; SHORT-LIVED RADIOACTIVITY; ALLENDE
METEORITE; CA-AL RICH INCLUSIONS; U-PB AGE; AL-26/AL-27 RATIO; REFRACTORY
INCLUSIONS; ISOTOPE FRACTIONATION; PLANET FORMATION; AL-26; METEORITES;
CHONDRULES; URANIUM; ORIGIN; LEAD; MG.