I also agree with Kim about the bulk of the IP response coming form the propylitic zone. However, I would like to see a few more examples of frequency domain IP done over some porphyry systems. I like the thought of being able to discern grainsize and/or mineral species.
Cheers Barry From: SEGMIN <[email protected]> On Behalf Of Kim Frankcombe via SEGMIN Sent: Sunday, 24 January 2021 9:46 AM To: [email protected] Cc: Kim Frankcombe <[email protected]> Subject: Re: [SEGMIN] Question for porphyry explorers Sergio It also depends on the integration window you use for chargeability, the frequency of your Tx or more correctly the length of the on time and a bunch of other geology factors. I don't stress too much about absolute values although I know plenty who do. If they want to walk away from an anomaly that is >2 times background it just leaves more for the rest of us to find. Having said all that typical anomalies are usually in the 2 - 4 x background level but I still wouldn't walk from something bigger, particularly if you can make a geologically cohearent story around it. The survey obviously has to be big enough to know what background is and for porphyries too many surveys never get out of alteration. The bulk of the IP response is coming from the propylitic zone not the primary mineralisation which while often chargeable is usually drowned out by the propylitic response. i.e you are looking for alteration more so than the ore. Cheers Kim On 24/1/21 4:49 am, S E Geoscience and Exploration via SEGMIN wrote: Dear all, Question for all those porphyry explorers: What chargeability value would you consider to be already anomalous for primary mineralization? Of course this value does not only depend on Sulphide-%, but also on its type of occurrence. Thank you in advance for the discussion, Regards -- Sergio Espinosa, Ph.D., P.Geo Director, Geophysics S E Geoscience & Exploration ----------------------- SEGMIN community mailing list service ([email protected] <mailto:[email protected]> ). Change your personal options here: https://lists.geosoft.com/mailman/options/segmin/kim%40exploregeo.com.au Colleagues can join here: https://lists.geosoft.com/mailman/listinfo/segmin Archives: https://lists.geosoft.com/mailman/private/segmin/ NOTE that <Reply> will reply to all members of the list. -- Kim Frankcombe Senior Consulting Geophysicist ExploreGeo PO Box 1191, Wangara, WA 6947 AUSTRALIA Unit 6,10 O’Connor Way, Wangara, WA 6065, Australia Phone +61 (0)8 62017719 - if your call goes to voice mail, leave a message. It converts to an email which I'll get where ever I am! Email [email protected] <mailto:[email protected]>
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