VTEM Case Study – Comparison with SkyyTEM: The Greenland ...geotech.ca/documents/greenland...
Transcript of VTEM Case Study – Comparison with SkyyTEM: The Greenland ...geotech.ca/documents/greenland...
IntroThis cgion’s
The Mprise of thea 15 kFinne
In 199with tby Skcover
The rin Figtigatiocondu
FiguresurveyVTEM
The rsedimstable
Figureof lakefiles fo
VTEM oduction case-study cons Greenland No
Maniitsoq area about 10% of t
e nickel discovekm wide by 75
efjeld Gneiss C
95 Cominco Lthe GeoTEM fix
kyTEM Surveysring some parts
results showed gure 1, due to Von. The tests auctors.
e 1: A) SkyTEM y area; B) corres
M & SkyTEM syst
reliability of the ments has beene and repeatab
e 2: A) SkyTEM es; B) correspondor VTEM & SkyT
24Pho
Case Stu
ncerns a direct orite Belt (GNB
is underlain prthe area and coered to date is km long “J”-shomplex.
d, in conjunctioxed wing, airbs ApS of Denms of the SkyTE
that the VTEMVTEM’s low nolso showed tha
helicopter EM syponding VTEM s
tem over a coinc
early time EMn chosen for suble between tim
helicopter EM syding VTEM systeEM system over
45 Industrial Pone: +1(905)8
udy – Com
survey compaB), in western G
redominantly byonsist mainly oassociated with
haped belt, refe
on with the Geoborne EM systemark took placeM block, was c
M system, by coise levels, highat, in contrast t
ystem vertical sesystem vertical cicent line shown
response can uch a comparisme gates, as we
ystem vertical seem early channer a coincident line
Parkway Nort841-5004, Fa
mparison
rison between Greenland.
y highly deformof amphibolite (h younger, underred to as the
ological Surveyem. Relatively fe in mid-Septemcompleted in Ju
omparison, deth dipole momeno SkyTEM, VT
econdary field placomponent of EM
in Figure 1A & 1
be checked ovon. As shown
ell as correspon
econdary field plal vertical compon
e from Figure 2A
h, Aurora, Onax: +1(905)84
n with Sky
the VTEM and
med and metam(metamorphosedeformed noriteGreenland Nor
y of Denmark afew EM anomamber to early Oune, 2012.
ected many mont, optimized w
TEM data provid
an view results (dM field time-consB (courtesy Nort
ver some shalloin Figure 2 andnding perfectly
an view results (dnent dBz/dt data
A & 2B (courtesy
ntario L4G 4C41-0611, www
yTEM: Th
d SkyTEM helic
morphosed Arced and deforme intrusions tharite Belt (GNB)
and Greenland alies were detecOctober of 2011
ore highly condwaveform, broadded more reliab
dBz/dt ch7 high-mstant over same arth American Nick
ow conductive d Figure 3, beloy to the lakes –
dBz/dt 0.031mseover same areaNorth American
C4, Canada w.geotech.ca
he Green
copter EM syst
chean gneissesed volcano-sed
at are concentr), which rims a
(GEUS), flew acted. Helicopte1. Later, a VTE
ductive targetsd bandwidth anble information
moment) over bearea; C) dBz/dt mkel Inc.).
sediments. Anow, the VTEM unlike SkyTEM
ec low-moment) oa as Fig. A; C) dB
Nickel Inc.).
nland Proj
ems over the M
s. Supracrustal dimentary sequrated in (but nolarge, complex
a large portioner EM surveyinEM survey (Geo
than did SkyTnd significant dn about weak a
edrock targets fromulti-channel EM
n area of GNB wearly times areM in most case
over GNB regionBz/dt multi-chann
ject
Maniitsoq re-
rocks com-uences). Most
ot restricted to) x known as the
of the GNB g of the GNB otech Ltd.),
TEM, as shown depth of inves-and shallow
om part of GNB M decay profiles f
with lake-bottoe more reliablees.
n showing outlinenel EM decay pro
e
for
m ,
e o-
FiguremomeRDI re
VTEMA higscale18-20
Figurehigh m
ConcThe cSkyT
1
2
3
4
5
6
7
e 3: A) SkyTEM ent and low momesistivity section
M-SkyTEM Nhly resistive pas (units conver
0 times noisier
e 4 - VTEM-Skymoment channel,
clusion current direct sEM systems:
1) The estimaSkyTEM sy
2) The VTEM
3) VTEM systclass of co
4) SkyTEM la
5) SkyTEM ea
6) Over the sata.
7) In marked for modelin
24Pho
survey grid and ent dBz/dt profilefor SkyTEM line
Noise-Level Cart of a line warted to pV/(A*min early times,
yTEM noise level shown at identic
survey compari
ated depth of ystem is not ab
M system’s resis
tem provides renductors.
ate time noise is
arly time noise
ame 140 sq. km
contrast, only ng.
45 Industrial Pone: +1(905)8
location of coinces (below) over loverlap (courtes
Comparison s chosen for th
m^4). The differas compared t
comparison ovecal vertical scale
ison in the GN
investigation (ble to detect hig
stivity resolutio
eliable respons
s greater than
is greater than
m area, as man
7-8 targets we
Parkway Nort841-5004, Fa
cident VTEM survine-segment ove
sy North America
he noise comparences are cleato VTEM, as sh
er resistive bedro, and B) early-ch
B area of Gree
(DOI) of the Vghly conductive
n, conductivity
ses from weak
VTEM late time
n VTEM early t
ny as 25-28 tar
ere obtained fr
h, Aurora, Onax: +1(905)84
vey line (L7020); erlapping VTEM an Nickel Inc.).
arison betweenarly obvious, whown in Figure
ock region at GNBhannel at 0.09ms
enland has hig
VTEM system ee targets below
range and sen
and shallow co
e noise by a fa
ime noise by a
rgets, sufficient
rom SkyTEM d
ntario L4G 4C41-0611, www
B) SkyTEM resisurvey ; C) VTE
n the VTEM anith the SkyTEM4, below:
B: A) late-channsec for VTEM vs.
ghlighted the fo
exceeds the Sw depths of 100
nsitivity are mu
onductors whe
actor of 20-25 ti
a factor of 18-20
tly reliable for m
data, including
C4, Canada w.geotech.ca
istivity section (aM dBz/dt multi-c
nd SkyTEM sysM being 20-25 t
el dBz/dt profile . SkyTEM low-m
ollowing differe
SkyTEM DOI b0-150 metres.
uch higher in co
ereas SkyTEM
imes.
0 times.
modeling, were
3-4 that were
above) and correhannel EM deca
stems, shown times noisier in
at 7msec for VToment channel d
ences between
by a factor of
omparison with
system is not
e obtained from
only conditiona
sponding high ay profiles and
using the samn late-times and
EM vs. SkyTEMdata.
the VTEM and
4-5 times. Th
SkyTEM.
sensitive to thi
m the VTEM da
ally appropriate
e d
d
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s
a-
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