The aeromagnetic data presented here are one data set collected as a
National Science Foundation (NSF) project entitled, "Lithospheric
controls on the behavior of the West Antarctic ice sheet." This is
a multi-institutional project that includes the Institute for
Geophysics of the University of Texas (UTIG) at Austin, the
Lamont-Doherty Earth Observatory (LDEO), and the U. S. Geological
Survey (USGS). The scientific objective of this program is to
understand the lithospheric framework across the West Antarctic rift
system in order to determine the geological controls on the dynamics
of the West Antarctic ice sheet. The Support Office for Aerogeophysical
Research (SOAR) collected the data.
These data show variations in the Earth's magnetic field caused
primarily by the uneven distribution of the mineral magnetite in the
rocks that make up the upper part of the Earth's crust. The
features and patterns of the maps reveal details of subsurface
geology including the locations of buried faults and
magnetite-bearing rocks, which include Cenozoic magmatic rocks, and
non-magnetic sedimentary and granitic rocks.
The aeromagnetic data were collected in 5 separate field seasons
covering 4 geographic regions (IRE, BSB, WAZ, TKD). Each survey
made simultaneous measurements of radar ice soundings, laser
altimetry, gravity (Bell and others, 1999), and magnetics. The
transects flown in all regions were separated by 5.3 kilometers
in both the flight-line and orthogonal tie-line directions. The
magnetic field observations are accurate to one nT.
High-resolution horizontal and vertical positions were obtained
from differential positioning techniques based on Global
Positioning System (GPS) satellites. When GPS satellite
positioning was unavailable, the laser altimetry was corrected
using attitude information from an inertial navigation system,
and a digital pressure transducer was used to recover vertical
positions and accelerations. The latitudes of the final composite
map ranged from approximately -77.8 to -84.5 degrees; the
longitudes from approximately -103.9 to -153.3 degrees. A data index plot gives an overview of the
names and locations of the geographic regions. A data table summarizes the survey
specifications, including dates flown and original flight
elevations. A list of data processing
steps details the procedures used to produce the final maps.
HPGL plot files can be downloaded for plotting
at a 1:1,000,000 scale for the composite IRE/BSB, WAZ/TKD, and
IRE/BSB/WAZ/TKD maps, and at a 1:750,000 scale for the individual
WAZ and TKD maps. GIF and page-sized color postscript plot files can be downloaded for all maps. All
maps are also available for screen
viewing.
This project was supported by National Science Foundation Grant
OPP-9319877 and by the Mineral Resources Team, the Global Change and
Climate History Team, and the Coastal and Marine Geology Team, all
of the USGS. The authors wish to thank our USGS colleagues Richard
Saltus and Kim Oshetski for their assistance in preparing this
report, and Robert Arko of LDEO for his assistance with the data
processing.