Abstract: Determining the Origin of Soil
Magnetic Susceptibility
Anomalies in Hydrocarbon Environments
COGOINI, MONIKA, University of Oklahoma, School of Geology & Geophysics, Norman, OK
Soil
magnetic susceptibility anomalies caused by magnetic mineral
authigenesis have been reported from hydrocarbon environments. The mechanisms
that could be responsible for the formation of the new magnetic phases
(e.g., magnetite) in such environments have only been described in theory.
For example, several types of microorganisms, including magnetotactic,
iron-reducing, and sulfate-reducing bacteria are capable of producing magnetic
minerals. It has not been investigated, however, whether those bacteria
could be responsible for the anomalous magnetic susceptibilities. The purpose
of this study is to test for a biogenic origin of authigenic magnetic minerals
above two oil fields, in the cap
soil
of a
landfill, and in laboratory experiments. Magnetic susceptibility will
be measured above and away from the oil fields. Samples will be analyzed
for their magnetic mineralogy, magnetic characteristics, and for the presence
of microorganisms that could cause the magnetic mineral formation. Furthermore,
the
soil
of a capped landfill which has locally elevated magnetic susceptibilities
will be microbiologically analyzed. In addition
soil
samples from control
areas will be exposed to: hydrocarbons in the laboratory and magnetic susceptibilities
and microbial content will be monitored over time Understanding the processes
that cause anomalous magnetic susceptibilities as detected by a rapid,
nearly noninvasive, and inexpensive method in hydrocarbon environments
is important for hydrocarbon exploration and seepage detection in the environmental
field.
AAPG Search and Discovery Article #90931©1998 AAPG Foundation Grants-in-Aid