Hi Mining Geophysical Dudes,
Neat Mining GP listserver -- thanx to Geosoft and Witherly for this little
forum. Here's a recent kimb study from the Crebs-files:
Mwenifumbo, C.J., Killeen, P.G., and Elliott, B.E., 1995. Borehole
Geophysical signatures of kimberlites in Canada. Minerals and Geotechnical
Logging Society Symposium--Santa Fe, New Mexico, USA--October,1995.
Summary:
GSC-types conducted multi-parameter borehole geophysical logs on the Fort �
la Corne kimberlite of Saskatchewan (uneconomic) and four pipes in the
Kirkland Lake Kimb Field of Ontario (also uneconomic).
Induced Polarization logs were run with magnetic susceptibility,
resistivity/conductivity, spectral gamma-ray (density and heavy element
indicator), temperature, 3-component magnetics, and P-wave seismic (sonic)
velocity logs.
Induced Polarization contrasts were apparently nill/uninteresting, as the
authors only mention IP was measured but IP values were not described or
tabulated!! However, diatreme and hypabyssal facies at the C14 kimb pipe
(Kirkland Lake) apparently showed distinct geophysical signatures--whereas
the diatreme facies kimberlites are characterized by lower density,
resistivity, gamma-ray, and magnetic susceptibility than the hyperbyssal
facies. In Saskatchewan, the density, mag-susc, and P-wave logs indicated
higher values in the reworked and altered crater facies of the Fort � la
Corne Pipe compared to the overlying sediments.
These GSC-dudes note that geophysical parameters vary considerable within
individual kimberlite pipes and between different pipes, primarily due to
different facies and source material of kimberlite intrusions.
Dudes (and dudettes), if you find a kimb with distinct anomalous IP, please
publish.
Regards,
Terry J. Crebs
Lakewood, Colorado
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