ELECTRICAL CONDUCTIVITY AND PRECAMBRIAN TECTONICS

BOERNER, David E., Geological Survey of Canada, 615 Booth St,
Ottawa, ON, Canada, K1A 0E9, boerner@cg.NRCan.gc.ca;
BAILEY, R.C., Department of Physics, University of Toronto,
Toronto, ON, Canada, M5S 1A7;
CRAVEN, J.A., JONES, A.G., and KURTZ, R.D.,
Geological Survey of Canada, 615 Booth St,
Ottawa, ON, Canada, K1A 0E9;
FERGUSON, I.J., Department of Geological Sciences, University 
of Manitoba, Winnipeg, MB, Canada R3T 2N2;
MCNEICE, G.W., Phoenix Geophysics Ltd., 3781-#3 Victoria Park Ave.,
Scarborough, ON, Canada, M1W 3K5;
JONES, F.W., Department of Physics, University of Alberta
Edmonton, AB, Canada, T6G 2J1;
WRIGHT, J.A., Department of Physics, Memorial University of
Newfoundland, St. John's NF, A1B 3X5.


Enhanced electrical conductivity, when genetically linked to a
particular geological process, can be a sensitive indicator 
of the conditions defining ancient orogenesis. At orogen scale,
concentration of conductive minerals within one particular
region is admitted by only a few distinct geological events.  
One important mechanism for generating conductive formations is the 
metamorphism of euxinic sediments, such as those deposited in 
foreland basin environments. That foreland basins have remained 
conductive since the Precambrian implies an initially high carbon 
productivity (or low consumption) and low energy sedimentation  
with subsequent metamorphism exceeding greenschist grade. Details 
of the  orogenic development are apparent in maps of the 
conductivity distribution. mostly in the form of consequent 
sediment dispersal patterns. Depth information, on the other hand, 
mostly indicates the style and extent of deformation suffered by the 
basin. However, to exploit the tectonic constraints hidden within 
models of electrical conductivity distribution requires a thorough 
understanding of the tectonic setting. Electrical conductivity data 
from different geological eras represented by the LITHOPROBE transects 
thus provide important information about the evolving chemistry of 
the ancient oceans and atmosphere, basin formation mechanisms, 
marine transgressions and margin destruction during orogenesis.