The pre-lecture dinner (5:30 pm in GeoCorner Room 320-109) requires reservation no later than 11/03/06, and is $30 regular, $5 for students; however no-shows owe full price.
Abstract
The title of this talk is also the title of a paper by Nobel Laureate
Harold Urey, published in the Astrophysical Journal 50 years ago. Most
meteorites last solidified from melt about 4.5 billion years ago, making
them the oldest objects available for study. The major motivation for the
study of meteorites is to use the evidence in meteorites to test models of
the early history of the solar system. For Urey, the fact that diamonds
were found in some meteorites implied that these meteorites must have once
been deep within a larger body, at least as big as the moon, at pressures
within the stability field of diamond. His model was undone by SRI
experiments showing that diamonds could be made by shock wave compression
and by the one-to-one correlation between presence of diamond and
metallurgical evidence for high shock pressures in individual meteorite
fragments.
The study of meteorites is truly interdisciplinary: Geochemists analyze and
date individual mineral grains, Metallurgists study diffusion profiles and
shock wave metamorphic effects to interpret thermal histories of
iron-nickel meteorites, Mineralogists and Shock Wave Physicists team to
interpret the shock pressure-temperature histories of deformational
features of stony meteorites.
This talk will give a broad overwiew of the current state of meteorite
research, with emphasis on the speaker's interests in shock wave effects
such as formation of high-pressure phases. Effects of large impacts,
including dinosaur extinction, the "big whack" model for formation of the
Moon, and delivery of Martian meteorites to the Earth, will be briefly
touched upon.
About the Speaker
http://www.diggles.com/pgs/2006/Paul06.jpg (photo of Paul)
Paul S De Carli is a Senior Scientist Emeritus at SRI International and an
Honorary Research Fellow in Earth Sciences at the University College
London. He writes: "I was drafted to give a talk at the Sept. meeting of
the American Society for Materials. After going to the work of preparing
that talk, I'd be happy to give it again to the PGS. I'd modify the talk
slightly, with more emphasis on high-pressure mineralogy and less emphasis
on metallurgy. One of our PGS regulars, Bob Wallace, was at the ASM meeting
and thought the talk would be appropriate for the PGS."
There is another page or two of interesting information about Paul's long
career at http://www.diggles.com/pgs/2006/PGS06-11.html
