Geology Reference
In-Depth Information
10
A Statistical Look at the U.S. Antarctic Meteorite Collection
Catherine M. Corrigan
1
, Linda C. Welzenbach
1
, Kevin Righter
2
, Kathleen M. McBride
2
,
Timothy J. McCoy
1
, Ralph P. Harvey
3
, and Cecilia E. Satterwhite
2
10.1. INTRODUCTION
scientists, teachers, writers, and even a few astronauts,
have returned more meteorites in ~35 years than were col-
lected by scientific institutions around the world in the
past few hundred years.
In this chapter, we examine the U.S. Antarctic mete-
orite collection from a statistical perspective, comparing
data from individual field sites, seasons, and other
meteorites collected in terms of types of meteorites
and the collection as a whole. One of the prime early
drivers for consistent and methodical characteriza-
tion of the entire U.S. Antarctic collection was to allow
such statistical comparisons. Early statistical assess-
ments of the U.S. Antarctic collection include
Harvey
and Cassidy
[1989],
Score and Lindstrom
[1990], and
Cassidy and Harvey
[1991], which together examined
mass distributions and the relative frequency of mete-
orite types for the collection as well as comparisons to a
defined set of modern falls.
More recent studies have looked at these statistics in
more detail. Principal component analysis was used by
Lipschutz and colleagues [
Wolf and Lipschutz
, 1995a,
1995b,
Michlovich et al
., 1995] to analyze labile trace
element data for H chondrites and argue that the flux of
H chondrites changed with time between the Antarctic
meteorites and modern falls.
Harvey
[1995] used model
size distributions to deconstruct the contribution of wind
movement, meteorite supply, and search losses to the
Antarctic collection. The mass-based statistics of the col-
lection were updated by
Cassidy
[2003], while size distri-
bution comparisons were similarly reexamined by
Harvey
[2003] and
Cassidy
[2003]. More recently, a series of
abstracts by
McBride and Righter
[2010] and
Welzenbach
and McCoy.
[2006] have examined various aspects of
statistics from the Antarctic collection, including
comparison with modern falls and Saharan meteorites.
Over the last century, the Antarctic ice has been an
amazing source for the collection of meteoritic material.
Meteorite recoveries in Antarctica prior to 1969 were
largely incidental and accidental to exploration or investi-
gation of the continent. As early as 1912, an Australian
expedition led by Douglas Mawson found an L5 chon-
dritic meteorite [
Mawson
, 1915]. In 1961, an iron was
recovered from the Humboldt Mountains in Adelie Land
by Russian geologists and a pallasite in the Thiel Mountains
by the United States Geological Survey (USGS). A fourth
(another iron meteorite) was found in 1964 in the Neptune
Mountains, also by the USGS [
Cassidy
, 2003].
The earliest systematic collection of meteorites by a
U.S. team in Antarctica began in 1976, when Dr. William
Cassidy (University of Pittsburgh) established the
ANSMET program. Initially done in collaboration with
Japanese colleagues [
Yoshida
, 2010], the U.S. program
quickly evolved into a sophisticated field and curatorial
program with the Smithsonian Institution, NASA, and
NSF (National Science Foundation) as partners. The
average number of meteorites collected during ANSMET
expeditions has steadily increased for a number of reasons
that include longer field seasons, better identification of
blue icefields, multiple teams (including those dedicated
to reconnaissance), and the use of a variety of aerial vehi-
cles to access more remote field sites [
Harvey et al
., 2014
(this volume)]. The field teams, composed of volunteer
1
Department of Mineral Sciences, National Museum of
Natural History, Smithsonian Institution
2
Jacobs Technology, NASA Johnson Space Center
3
Case Western Reserve University, Department of Earth
Environmental and Planetary Sciences
