
TY  - JOUR
A1  - Lilley, F.E.M. 
T1  - On the spatial pattern of magnetic fluctuations in the Cobar area, NSW
JF  - Exploration Geophysics
JO  - Explor. Geophys.
Y1  - 1984
VL  - 15
IS  - 2
SP  - 79
EP  - 83
KW  - 
UR  - https://doi.org/10.1071/EG984079 
N2  - Five recording magnetometers have been established in the Cobar area of NSW to examine the spatial uniformity (or otherwise) of natural fluctuations with time of the geo- magnetic field. The Cobar area is a particularly suitable test area for such a study because of its history in the development and use of magnetic survey methods in the search for base metal ore deposits, and because magnetic fluctuations are now a limiting factor in the production of accurate aeromagnetic survey maps. The magnetic fluctuations in the Cobar area are found to be not uniform, but appear affected by a current concentration in the vicinity of the east side of the Cobar basin. Thus changes as great as 25% in magnetic fluctuation amplitude are observed over distances of order 30 km (and may occur over even shorter distances). Some differences are also observed in the amplitude of the east-west component of the magnetic daily variation. The phenomena are interpreted to indicate a geologic unit of good electrical conductivity (possibly the Cobar slate member of the Cobar Trough group) which runs along the eastern edge of the basin, and carries a concentration of the natural electric current flow induced in the earth. 
ER  -

