Steve/all:
On the BHP web site at:
http://www.bhp.com/default.asp?page=951#
a profile over a pipe is shown comparing Falcon data with ground data. The
lateral resolution for Falcon (as shown) is certainly better than 250m
(maybe some good old predictive filtering?).
I don't see any 'flowering effect' in this example; the anomaly is wider
than the pipe but simply fits the width of the lake, the other major
(primary?) source of the observed density anomaly in these lake-pipe duet's
that are so common in the NWT.
In the text at the top of the same page, there is also discussion regarding
not seeing a pipe of dimensions 140m by 100m, so there is seems to be a gray
area as to what can be resolved.
Ken
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Stephen Reford
Sent: Tuesday, January 09, 2001 11:42 AM
To: [EMAIL PROTECTED]
Subject: Re: [SEGMIN]: But what can it do?
Terry,
Apparently, kimberlite pipes result in a "flower"-type response in the
parameters derived from the Falcon data that have a much larger dimension
than the pipes themselves. I understand that BHP detected one pipe with a
60 m diameter.
Cheers! Stephen
On Tue, 9 Jan 2001 [EMAIL PROTECTED] wrote:
>
> In a message dated 1/9/01 6:36:58 AM, [EMAIL PROTECTED] writes:
>
> << Based on information that has appeared elsewhere, BHP states as
acquisition
>
> cost for Falcon of ~US$60 lkm (or $15/station since they as well state
they
>
> measure data at about a 250 sample interval). This is about airborne EM
>
> comes in at, so is not out of line. However, BHP's right to a 51% interest
>
> certainly looks like you've invited the proverbial 800 lb gorilla to
>
> dinner >>
>
> Sheesh, Ken, I think 250-meter gravity-gradient-sampling is downright
> terrible for kimberlite exploration.
>
> Very few economic pipes on the planet, if I remember right, have surface
> dimensions in excess of 250 meters. The giants like Mwadi, Orapa, Jwaneng
> (with grades less than 1 carat/tonne) probably would be nicely imaged with
> 250-meter gradient-stations. BUT, smaller (less than 20-million-tonne) but
> high-grade pipes (>4 carats/tonne) like Mir, International, and even
> Lac-De-Gras' Misery and A-154-South pipes could be trouble for any
> 250-meter-station technique. Even with the averaging/smearing inherent in
> airborne geophysical sampling--I'd be worried about "missing" the
high-grade
> but smaller kimb target.
>
> Comparing line-kilometer costs between HEM and Falcon is similar, but the
> high (<10-metre) sampling-rate of HEM probably still make it the superior
> airborne method for my kimberlite exploration programs. I believe Falcon
> probably has greater exploration potential in oil/gas exploration where
basin
> targets/structures are large and shallow density-contrasts are better
known
> thanx to 3D-seismic-static-corrections.
>
> Thanks for posting the BHP-Falcon promotional stuff, it is always
> interesting.
>
> Best Regards,
> Terry J. Crebs
> California Registered Geophysicist
> Lakewood, CO USA
>
>
>
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