|
G410 / G510 Meteorites
Fall Term 2003
MWF 9:00 - 10:05 am, CH 69
A. Ruzicka (+ iron meteorites + muffin)
e-mail: ruzickaa@pdx.edu
Images of two very different meteorites, the Murchison (CM2) chondrite
at left, and the Henbury (IIIAB) iron at right.
Murchison was derived from an asteroid that never melted,
and which was rich in water and organic
materials. These organic materials provide evidence for pre-biotic
synthesis of organic molecules,
which appear to have formed originally in the interstellar medium.
Bright spots in the meteorite are chondrules and refractory inclusions;
fusion crust is the
brown coating at left.
In contrast, Henbury was derived from the core of a melted
asteroid.
The core cooled very slowly (roughly 1 degree C per million years!)
owing to its deep burial in the
parent body. This slow cooling enabled the low-nickel metal
alloy mineral kamacite to exsolve from the
high-nickel metal alloy mineral taenite, producing the intergrowth
pattern (Widmanstatten texture) obvious
in the image.
Course information
-
Reading list.
This is the list for the whole term. See the "Glossary and concepts"
and "Homework assignments" sections for more details on sections of the
readings to skim.
-
10-17-03
Change to schedule. As mentioned in class, I am tweaking the
schedule a bit to make some more time to focus on the main papers and to
allow time for review. The mid-term will occur on the same day as
originally planned, but will include topics covered only through
Oct. 27.
Glossary and concepts
-
Clayton
(1993), "Oxygen isotopes in meteorites" This paper assumes a
high level of background knowledge. Don't worry if you don't understand
all of it. The link leads to a good primer on oxygen isotopes that
you may find useful before looking at the Clayton paper.
-
Wadwha
& Russell (2000) and Lugmair & Shukolyukov (2001). There
is considerable overlap between these two papers on the Mn-Cr system, and
I think the latter article presents a clearer description of this, whereas
the former is a better overview of other systems. You might want
to take this into account as you allocate time for the readings.
For the Wadwha & Russell paper, do a rapid read of section IIB.
For the Lugmair & Shukolyukov paper, skim much of the "Age of the Solar
System" section, except pay closer attention to Fig. 5 and the last ("Some
constraints...") portion.
-
Wasson
(1985), "Iron meteorites: Evidence for and against core origins".
In addition to reading this paper, you should take another look at the
last part (pp. 227-234) of the Dodd (1981) reading, our second one of the
term. Dodd discusses various chemical processes that affected iron
meteorites, whereas Wasson focusses almost exclusively on fractional crystallization.
Other reference materials
-
Introduction to meteorites.
Click here
to open a Powerpoint file (6.7 Mb). The video clip may not work on
your system.
-
Asteroids. Click here
to
open a Powerpoint file (6.9 Mb). This presentation covers many of
the topics we have read about (orbits, spectra & albedo, space weathering)
and also shows images of asteroids.
-
Young stellar objects. Click
here
to open a Powerpoint file (1.8 Mb). This presentation is about newly-forming
and newly-formed stars that have protoplanetary disks. There's even
an image that provides support for the nebular shock (clumpy accretion)
model of chondrule formation.
-
Meteorite
image gallery. This page contains images retrieved from the web.
It will be periodically updated. [Last update: 11-14-03.]
Homework assignments
Score distributions and answer
keys
Last Updated: 12-14-03
|