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

e

s

a-

e