Fieldwork Methods of the U.S. Antarctic Search for Meteorites Program - 35 Seasons of U.S. Antarctic Meteorites - page 23

2

Fieldwork Methods of the U.S. Antarctic Search
for Meteorites Program

Ralph P. Harvey, John Schutt, and Jim Karner

2.1. INTRODUCTION 1957 International Geophysical Year. The global and

developmental nature of that effort led to the high level
of scientific activity in Antarctica that continues today.
During those early years, three meteorites were discov-
ered during geological surveys: Lazarev, an iron recov-
ered in two fragments from the Humboldt Mountains in
January of 1961; Thiel Mountains, a pallasite recovered
in two fragments in December of the same year; and
Neptune Mountains, a single iron recovered from the
Pensacola Range in February of 1964. Both Lazarev
and Neptune Mountains were discovered on mountain
slopes during geological surveys and were not associated
with any obvious glacial processes [ Tolstikov , 1961;
Turner , 1962; Ravich and Revnov , 1963; Duke , 1965].
Thiel Mountains, on the other hand, was a harbinger of
the future; the two fragments were found on “hard, irreg-
ularly cupped glacier ice” to the northeast of Mount
Wrather, associated with morainal debris, as described
by Ford and Tabor [1971]. These authors also noted that
the association of the specimens with morainal debris
implied that the specimens had been transported from
their original fall site, and that the weathering state of
the specimens implied that abrasion in the cold, dry kata-
batic winds of the polar plateau was extremely effective
as a local mechanism of erosion. Their observations
proved prescient; the Thiel Mountains pallasite deserves
consideration as the first meteorite recovered from an
Antarctic meteorite concentration surface (as later recov-
eries from the region would confirm). Unfortunately, it
was the only meteorite located at that time, and thus the
concentration at Thiel Mountains would not be recog-
nized until 1982 [ Schutt , 1989].
There is little ambiguity as to the event that revealed
the existence of Antarctic meteorite concentrations. On
21 December 1969, Renji Naruse of the tenth Japanese

The U.S. Antarctic Search for Meteorites (ANSMET)
program has recovered more than 20,000 meteorite speci-
mens since fieldwork began in 1976. The methods
employed during fieldwork have evolved considerably over
that interval in response to demand, logistical support,
and an improved understanding of the links between
Antarctic meteorite concentrations and their geographical
and glaciological setting. This chapter describes how
ANSMET fieldwork has evolved over the years to pro-
duce the current meteorite recovery methods and discusses
how they relate to the complex phenomena of Antarctic
meteorite concentrations, both in theory and in practice.

2.2. ANSMET FIELD SEASONS YESTERDAY
AND TODAY

2.2.1. ANSMET's Place Among Modern Antarctic
Meteorite Recovery Efforts

Meteorites have played a role in Antarctic science since
the earliest years of the twentieth century. The first mete-
orite recovered from Antarctica, about 10 cm across and
fully fusion crusted, was found by one of Douglas
Mawson's field parties in 1912, lying on hard snow on the
Adelie Coast [ Mawson , 1915]. F. L. Stillwell, a geologist
in the field party, immediately recognized the rock as a
meteorite and studied it in detail after the expedition
returned to Australia [ Bayly and Stillwell , 1923]. Four
decades later cooperative international scientific explo-
ration of the Antarctic continent commenced with the

,