0800h
AN: GP21A-0119
TI: Frequency Dependent Susceptibility
Analysis of Magnetic Carriers: Application to Fe-Oxides on Mars surface
AU: * Adachi, T
EM: tomoko.adachi@gsfc.nasa.gov
AF: Department of Physics, Catholic
University of America, 200 Hannan Hall, 620 Michigan Ave
NE, Washington, DC 20064, United States
AU: * Adachi, T
EM: tomoko.adachi@gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Code
691, Division of Solar System Exploration,
Greenbelt, 20771, United States
AU: Kletetschka, G
EM: kletetschka@nasa.gov
AF: Department of Physics, Catholic
University of America, 200 Hannan Hall, 620 Michigan Ave
NE, Washington, DC 20064, United States
AU: Kletetschka, G
EM: kletetschka@nasa.gov
AF: NASA Goddard Space Flight Center, Code
691, Division of Solar System Exploration,
Greenbelt, 20771, United States
AU: Kletetschka, G
EM: kletetschka@nasa.gov
AF: Institute of Geology, Academy of Science
of the Czech Republic, Rozvojová 135, Prague,
165 02, Czech Republic
AU: Mikula, V
EM: mikula.vilem@ssedmail.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Code
691, Division of Solar System Exploration,
Greenbelt, 20771, United States
AB:
On Mars, Fe-oxides mineral phases (inferred/detected) are mainly
magnetite, pyrrhotite, and hematite.
Kletetschka et al., 2005 suggested that the grain size dependent
potential may contribute to the Mars surface
magnetic anomaly. Grain size of Fe-oxides may play a role for the
magnetic signature and anomaly on Mars.
According to Kletetschka et al., 2005, the larger the grain size, the
larger the magnetization (in this case
hematite's TRM). Weather they are magnetite, pyrrhotite or hematite,
nano-phase or superparamagnetic grains
may contribute to the absence of remanent magnetization on the surface
of Mars. In this contribution we tackle how to resolve grain size
variations by frequency dependent susceptibility
measured on terrestrial hematite samples such as hemo-ilmenite from
Allard Lake, Canada, Mars analogue
concretions from Utah and Czech Republic, and hematite aggregates from
Hawaii. The magnetic characteristics
of hematite-goethite mineralogies of Utah and Czech concretions
suggested (Adachi et al., 2007) that they
contain super paramagnetic (SP) to single domain (SD) magnetic states.
Coercivity spectra analysis from
acquisition of isothermal remanent magnetization (IRM) data showed the
distinct behaviors of hematite, goethite,
and mixed composition of both. The estimated magnetic states are
analyzed with the frequency-dependent
susceptibility instrument (500-250,000 Hertz). The frequency- and
size-dependent susceptibility for hematite,
goethite, and magnetite are calibrated using the known size powdered
(commercial) samples.
UR: http://lep694.gsfc.nasa.gov/gunther/gunther/publications.html
DE: 1517 Magnetic anomalies: modeling and
interpretation
DE: 1518 Magnetic fabrics and anisotropy
DE: 1540 Rock and mineral magnetism
DE: 1595 Planetary magnetism: all frequencies
and wavelengths
DE: 1599 General or miscellaneous
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting