I have done a resistivity and induced polarization (IP) in a granitic area of generally S-type, tin bearing. The resistivity method detected a massive anomaly of >3,000 ohm.m which represent the granites of at least 40m depth.
But within the anomaly itself, a range of chargeability (17- 800 msec) did also appear.
What does contribute the chargeability values like that?
Could there any clayey minerals exist within the granites? Or is it related to any mineralization i.e greisen or sulfide in the hard rock?
Without more information on your surface geology, this is a guess, but granites gnerally weather along joints formed as the overlying cover is eroded. In areas of deep weathering, clay could form along joints. It is also possible that a mafic dike of some variety could be causing this phenomenon. Sulfide mineralization is also a possiblity.
I agree with horizontal jointing. In Finland we have also ca 1830 ma posttectonic granites intruded along gently dipping 'collapsing' structures (i.e. 'shear'). Possibly also MoS2, if I remember, it could be conductive.
Well looking at the high chargeability which is related closely to clayey minerals, It is possible that the abundant K-Feldspar minerals in Granite are undergoing weathering. And at that depth, it might be there are fractures that are providing the conduits for fluid transport for chemical weathering. I suspect fluids through certain structures. Any identifiable fractures? Please let me know your thought.
Thanks
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