2289 GA Kimberley Logistics Report

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Airborne Geophysical Survey

South Kimberley, Western Australia

Project 1149

Surveyed January - September 2008

Survey Operations and Logistics Report

Prepared for


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1 GENERAL SURVEY INFORMATION .......................................................................................................3

1.1 INTRODUCTION ....................................................................................................................................31.2 SURVEY SUMMARY ..............................................................................................................................31.3 SURVEY PERSONNEL ...........................................................................................................................5

2 SURVEY SPECIFICATIONS.....................................................................................................................6

2.1 SURVEY MAPS ....................................................................................................................................6

2.2 SURVEY SPECIFICATIONS...................................................................................................................10

3 EQUIPMENT SPECIFICATIONS ............................................................................................................12

3.1 SURVEY EQUIPMENT SUMMARY ..........................................................................................................123.2 DATA ACQUISITION EQUIPMENT..........................................................................................................133.3 MAGNETOMETER PROCESSOR ...........................................................................................................143.4 MAGNETOMETER SENSOR .................................................................................................................153.5 FLUXGATE MAGNETOMETER ..............................................................................................................153.6 SPECTROMETER ................................................................................................................................16

3.7 BAROMETRIC PRESSURE SENSOR ......................................................................................................163.8 RADAR ALTIMETER ............................................................................................................................163.9 DGPS RECEIVER ..............................................................................................................................173.10 BASE MAGNETOMETER ......................................................................................................................17

4 EQUIPMENT CALIBRATIONS AND DATA ACQUISITION CHECKS ..................................................21

4.1 DYNAMIC MAGNETOMETER COMPENSATION .......................................................................................214.2 HEADING ERROR CHECK ...................................................................................................................294.3 SYSTEM PARALLAX TESTS .................................................................................................................30

4 4 PRE SURVEY RADIOMETRIC CALIBRATION TESTS 31


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1 GENERAL SURVEY INFORMATION

1.1 INTRODUCTION

In January 2008, GPX Airborne commenced a fixed wing airborne magnetic andradiometric survey for Geoscience Australia in the Kimberley region, Western Australia.

The survey was flown using a Cessna 210 fixed wing aircraft with registration VH-KWW.This report summarises the procedures, details and equipment used by GPX Airborne inthe acquisition, verification and processing of the airborne geophysical data.

Client: Geoscience Australia

GPX Project Number: 2289

Survey Area: Kimberley SE and Kimberley SW, WA

Field Bases (WA, 2008):

Kimberley Hotel, Halls Creek 17th January 3rd April

Fitzroy River Lodge, Fitzroy Crossing 3rd April 14th May

Kimberley Hotel, Halls Creek 14th May 31st July

Fitzroy River Lodge, Fitzroy Crossing 31st July 2nd August


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compensation box flight and the first production flight was flown. The final flight was on 3rd

October 2008.

Data acquisition was monitored in the aircraft and preliminary data checks were performedafter each flight at the field bases. At the end of each days flying all data was sent back tothe offices of GPX Surveys for further processing and review. Throughout the survey

system stability and continuity had been monitored.

During the survey there were 17.5 days lost due to weather. There was an additional 51.0days down time during the survey due to scheduled and unscheduled aircraft andequipment maintenance. Thirty (30.0) of these days were for standard hundred and fiftyhurly maintenance. Between 24th August and 23rd September 2008 flying was suspendeddue to mustering in the survey area.

The aircraft was unable to fly over Ellendale mine due to regular blasting taking place. Thisaffected lines 300940 300991, 301130 301132 and 301150 301161.


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1.3 SURVEY PERSONNEL

The following personnel were involved on this project:

Airborne Operations Manager: Bob Blizzard

Project Manager: Don Copley

Liam Parry

Shane Hulme

Michael Pritchard

Operators: Raphael Fisher

Dean Reynolds

Donna Donavan-Hicks

Jeff Ibbotson

Tom McLeod

Phil Kitto

Ian Brown


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2 SURVEY SPECIFICATIONS

2.1 SURVEY MAPS

Overview Map

The following map provides an overview of the planned survey area.


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Detail Maps

Detailed maps of the planned survey areas are shown below.


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1:250,000 Sheet Name

Lennard RiverLansdowneNoonKanbahMount RamsayCrossland

Mount BannermanCharnleyMount ElizabethYampiDerbyDixon RangeGordon DownsBilliluna


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2.2 SURVEY SPECIFICATIONS

Job Specifications

The following are the flying specifications, equipment sample rates and line specificationsfor the survey:

Flying Specifications

Minimum line length: 5000 metres

Nominal ground clearance: 60 m

Sample Rates

Magnetometer: 10 Hz

Altimeter: 1 Hz

Base magnetometer: 1 Hz

Spectrometer: 1 Hz

Li S ifi ti B th S A


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Boundary Coordinates

The following coordinates are in GDA94 MGA52 and define the survey areas:

South West

KimberleyPoint Easting Northing

1 20594 8114933

2 160297 8117678

3 136114 8105173

4 136488 8082615

5 164354 8082789

6 164210 8094661

7 180904 80949278 183203 7951862

9 130354 7950909

10 129293 8006312

11 76269 8005238

12 21922 8058049

S th E t


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3 EQUIPMENT SPECIFICATIONS

3.1 SURVEY EQUIPMENT SUMMARY

Aircraft installation was done in October 2007. System tests and calibrations wereconducted in October 2007 and January 2008. The following equipment was used in the

survey.

Survey Platform: Cessna 210 (VH-KWW)

Data Acquisition and Survey System: Pico Envirotec AGIS PC104

Magnetometer Processor: Pico Envirotec MMS-4

Magnetometer Sensor: Geometrics G-822A Cesium Vapour

Fluxgate Magnetometer: Billingsley Ultra Miniature TFM 100G2

Magnetic Base Stations: GEM GSM-19W Overhauser

Spectrometer: Exploranium GR820 (32 litre crystal)

Temperature and Humidity Sensor: Vaisala HMP233

Barometric Pressure Sensor: Vaisala PTB220

GPS d DGPS R i CSI DGPS M


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3.2 DATA ACQUISITION EQUIPMENT

The data acquisition console is a Pico Envirotec AGIS PC104. This is a versatile multi-function system that is capable of operation in many different configurations, depending onplatform type, navigation and system requirements. For this survey the AGIS PC104 wasused for navigation and flight control, data recording, real-time monitoring of magnetic dataand data retrieval.

Navigation and Flight Control

The AGIS PC104 is used to guide the aircraft on a pre-defined flight plan that can begenerated in UTM or Latitude/Longitude coordinates. The pre-defined flight plan can bedesigned to file prior to the start of the project, entered or altered in the AGIS system ordelineated on-the-fly e.g. while in the air flying the boundary and entering cornercoordinates. Co-ordinates can only be entered in the WGS84 datum system, this has beenimplemented to avoid confusion and eliminate possible conversion errors. Normal surveyaltitude and ground speed, with pre-set tolerances are also entered.

The pilot display consisted of a 2-line strip display or more comprehensive Pilot GuidanceUnit (PGU). The strip display is driven directly from the AGIS PC104 console; whereas thePGU is a self-contained computer system that is capable of more demanding navigationfunctions such as drape flying using a pre-programmed altitude grid.

Th d i d fli ht li i l t d f th t i t f hi h ill ith b


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Several other status indications are also provided which will either change state indicatinga major system malfunction, such as a magnetometer failure, or will change state duringnormal operation, indicating data being written to a file etc.

Figure 5: AGIS real-time data and status display.


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Specifications

Input: Coaxial - Larmour signal over DC Power

Supply

Resolution: 0.0002 nT (Gamma) = 0.2 picoTesla

Sampling rates: 5, 10, 20, 25, 50, 100 Hz

Dynamic range: 15,000 to 100,000nT

Synchronization: GPS PPS (Pulse Per Second)

3.4 MAGNETOMETER SENSOR

The magnetometer sensor is a Geometrics G-822A, which employs an optically pumpedcesium-vapour atomic magnetic resonance system that functions as the frequency controlelement in an oscillator circuit.

Specifications

Operating Range: 20,000 100,000 nT

Sensitivity: Typically 0.002 nT P-P at a 20Hz sample


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3.6 SPECTROMETER

The spectrometer is an Exploranium GR820 system. The unit comprises of 2 detectorcrystal packs which give a total volume for detection of 32 litres. The spectrometeremploys automatic gain stabilisation control to eliminate the need to heat the detectors.Signal processing automatically perform digital gain control to the individual crystal

spectra, ensuring the summed spectrum is stable.

Specifications

Sensitivity: 0 3.0 MeV

Maximum count rate: 100,000 counts/sec

Detector volume: 16.7 Litres (each)

Detector weight: 83.9 kgs (each)

3.7 BAROMETRIC PRESSURE SENSOR

The barometric pressure sensor is a Vaisala PTB220. The unit provides both a digitalRS232 output and Analogue voltage or current output directly proportional to themeasured Barometric Pressure. The unit is a Class A commercial grade device housedin a rugged aluminium enclosure.


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3.9 DGPS RECEIVER

The DGPS receiver is a CSI DGPS MAX, which is a 12-channel combined GPS/DGPSunit. The DGPS MAX is able to use differential corrections received through an internalWAAS demodulator, VLF beacon receiver, or the OmniSTAR DGPS Service. The DGPSposition data was used for aircraft navigation and for processing the aeromagnetic data.

SpecificationsGPS Position update rate: 5Hz

GPS Input frequency: L1

DGPS Update rate: Typically every 6 seconds

DGPS Solution Used: OmniSTAR VBS

Antenna: Fugro L1/Differential Wideband

3.10 BASE MAGNETOMETER

Diurnal activity was monitored using portable GEM GSM-19W Overhauser magnetometersand sampled at 1 Hz. The unit has a built-in GPS receiver.

Specifications


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Base Station Location

Halls CreekThe primary base station at Halls Creek was located near the air strip.

Location

Coordinates: 018.2333584S 127.6669168E

Datum: WGS84


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Fitzroy CrossingThe primary base station at Fitzroy Crossing was located near the air strip.

Location

Coordinates: 018.1781782S 125.5627280E

Datum: WGS84


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DerbyThe primary base station at Derby was located near the air strip.

Location

Coordinates: 017.3656406S 123.6697823E

Datum: WGS84


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4 EQUIPMENT CALIBRATIONS AND DATA ACQUISITION CHECKS

4.1 DYNAMIC MAGNETOMETER COMPENSATION

Aircraft compensation tests were flown at high altitude on the 4 survey line headings andalso at +/-15 to the line headings (to accommodate for cross wind flying conditions). The

data for each heading consists of a series of aircraft manoeuvres with large angularexcursions: specifically pitches, rolls and yaws. This is done to artificially create the worstpossible attitudes and rates of attitudinal change likely to be encountered while on line andcompensate for any magnetic noise created by the aircraft's motion within the earth'smagnetic field. This data is processed to obtain the REAL TIME COMPENSATION termsof which the aircraft used the standard 17 term model. These terms include permanent,induced and eddy values. These coefficients may be applied in real time or during postprocessing. Note that this form of compensation will only remove those noise effects

modelled in the manoeuvres test flight. External noise sources and random motions of thestinger with respect to the aircraft airframe generally establish the noise floor for this typeof installation. The surveyor's goal is to achieve a 4th difference noise level on the order of0.01 nT RMS during normal surveying conditions. In general, this noise level was routinelyachieved or bettered as a matter of course.

The following is a list of dates in which a compensation test had been flown and the flights

th d


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Magnetic compensation flight path

The images below are of the compensation flight paths.


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Diurnal activity during compensation flight

The diurnal collected during the compensation flight was relatively quiet as shown in thefollowing figure.


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Compensation results (24th January 2008)


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Compensation results (30th January 2008)

Figure 17: East bound compensation line (30th

January 2008).


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Figure 19: North bound compensation line (30th

January 2008).


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4.2 HEADING ERROR CHECK

Historically, heading error checks have been an essential part of the aeromagnetic dataacquisition procedure but their importance now has diminished. GPX Surveys nowcorrects for these effects using the dynamic aircraft magnetic compensation system andspecially developed software. In the past, repeatable heading errors of less than onenanotesla (1.0 nT) were considered good. Dynamic compensation typically yields heading

errors in the order of 0.1 to 0.3 nT, which are effectively eliminated by modern datalevelling techniques.

Below are the results of the heading error check of VH-KWW at commencement of survey.

Line Heading Minimum Maximum Mean HeadingStdDev

#readings

L95101005:0 East 50653.46 50656.08 50654.81 0.55 0.79 33

L95201005:0 North 50654.34 50656.24 50655.29 0.07 0.59 30L95301005:0 West 50654.08 50656.60 50655.37 -0.01 0.76 33L95401005:0 South 50655.18 50657.14 50656.14 -0.78 0.59 26

ALL 50653.46 50657.14 50655.36 0.83


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Pi = Instrument parallax

Results of parallax test

A summary of the parallax corrections to the different data types is shown below:

Data Parallax applied (seconds)

GPS Position 2.5Magnetic Data 1.6Radiometric data 0.0Radar Altimeter 1.5Barometric Altimeter 1.5GPS derived DEM 1.0Barometric derived DEM 1.0

Temperature 1.5Pressure 1.5Humidity 1.5GPS Altimeter 1.0Fluxgates 0.0

4.4 PRE-SURVEY RADIOMETRIC CALIBRATION TESTS


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U 0.008227Th 0.006851

Dose 29.9564K 95.99U 9.69

Air/Ground @50m 4 Jan 2008

Th 6.15

Dose 27.87K 88.14U 8.82

Air/Ground @60m 4 Jan 2008

Th 5.82

4.5 DAILY RADIOMETRIC SYSTEM TESTS

Daily tests were performed on the radiometric system to monitor system sensitivity and

stability. These tests are as generally described by Grasty and Minty (1995) and theInternational Atomic Energy Agency (2003).

A system stability test was performed at the start and end of each day. This was doneusing a thorium source placed a least 40cm from the centre of each detector. Theaverage deadtime and background corrected thorium window was calculated and checkedto be within 3 percent from the average of all other calibrations.


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Low Level Test Line Location

Figure 23: Low level test lines flown from Fitzroy and Derby air bases.


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GPS Height Data Checks

The aircrafts height above mean sea level was determined by data from the post-processed GPS data. The GPS height of the aircraft is checked for data masking andequipment reliability. The aircraft GPS recorded the data in the WGS84 datum.

Flight Path Checks

The flight path was plotted against the flight plan and checked for deviations. Anysignificant deviations were queried with the pilot and flagged. The section was thenchecked against contract specifications and if it was out of specification the section waschecked against SRTM data and compared to terrain information in Google Earth. If noneof these revealed a valid reason for being out of specification the section was re-flown.The aircraft GPS recorded the data in the WGS84 datum.

Digital Terrain Data

After radar and GPS height data verification the radar altimeter height was subtracted fromthe GPS height to give the elevation of the terrain above mean sea level. The digitalterrain data and was gridded to check for inconsistencies and errors.

Radiometric Data

The 256-channel radiometric data was viewed to confirm that the spectra peaks arecorrectly calibrated. The following peak locations were checked daily:


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6 FINAL PROCESSING

All final checks, verification and data processing were performed in the offices of GPXSurveys. The raw field data was transferred to the GPX Surveys ftp site at the end ofeach flight. The final processing of the data follows the same quality control checks thatare made in the field however the final data has additional processes performed. No field-

processed data was used in the making of the final data.

All data used in the final processing was within contract specifications.

The following software was used in the final verification and data processing:

GPX proprietary software

ChrisDBF Geosoft Oasis Montaj

6.1 FINAL MAGNETIC DATA PROCESSING

Initial checks on the field data were performed as described in section 5.1.


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IGRF Correction to the Magnetic Data

The diurnally corrected magnetic data has been corrected for the regional gradient bysubtracting the calculated IGRF (2005 model) computed continuously over the whole area.The calculation of these corrections used the GPS flying height. An IGRF base value of50620 nT was added to the data.

Tie Line Levelling

A crossover program was used to compute the magnetic difference between each tie lineand the traverse line intersection. These differences were then applied to level thetraverse lines to the tie lines.

Micro Levelling

Finally the data was micro-levelled using a proprietary program that more subtly levels the

data. Micro levelling was used to remove residual differences with a long wavelengthalong line and short wavelength across line. Application of the micro-levelling processremoved the streaks that were sometimes visible when using various grid enhancements.The process used a window width of 12 grid cells and a tolerance of 3 nanoTesla.

Gridding and Inspection

The magnetic data was gridded and grid image enhancements were computed anddisplayed on screen. These were also viewed with the aid of crossline sun angles and


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The height data was corrected to standard temperature and pressure and then

corrected to a nominal survey height using height attenuation coefficients.

If necessary the data was levelled using tie line levelling and/or micro levelling

techniques.

The data was converted to elemental concentrations.

Noise Adjusted Singular Value Decomposition (NASVD)

The two most common processing methods for 256 channel noise reduction are:

1. Noise Adjusted Singular Value Decomposition (NASVD). This was developedspecifically for radiometric processing.

2. Maximum Noise Fraction (MNF). This was developed for removing noise fromsatellite images and subsequently used in radiometric processing.

Both methods use Principal Component Analysis (PCA) with the only difference being inthe estimation of noise in the raw spectra and subsequent scaling before PCA.

We have implemented and extensively used both methods but prefer NASVD because it is


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significant terrain variation where aircraft attitude movements will allow ground signal to berecorded by the upward looking crystals.

It is clearly evident that any effective radon correction method should use the downwardlooking crystals only.

For this reason we prefer to use the spectral ratio method for radon removal. This method

uses the 352 keV uranium peak as a substitute for upward crystals. The only time upwardcrystals may be needed is where cesium contamination affects the use of the 352 keVuranium peak. The use of the low energy uranium peak at 352 keV instead of the 609 keVuranium peak should make even this use of upward crystals redundant. The 352 keVuranium peak is an extremely good detector of radon gas because very little radiation fromthe ground will reach the aircraft at this low energy. Also the thorium peak close to the 352keV peak has much less intensity than the thorium peak close to the 609 keV uranium

peak.

Stripping Corrections

The radiometric spectra of potassium (K), uranium (U) and thorium (Th) series overlap. Toevaluate of any one spectral window, which is designed to detect one radioelement,requires removal of the spectral overlap. This process of removal of the spectral overlap isknown as stripping. The stripping procedure uses spectral stripping ratios determinedexperimentally using concrete calibration pads of known K, U and Th concentration. The


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Figure 25: Histogram analysis of difference between the final GPX DEM grid and the 9 second DEM of


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8 MAP IMAGES

8.1 FLIGHT PATH


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8.5 RADIOMETRIC TERNARY CMY COLOURS

Figure 30: Radiometric ternary CMY colours image.


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9 CONTRACTOR INFORMATION

GPX Surveys Pty Ltd ABN 48 110 619 602

Address: 4 Hehir Street, T +61 8 9477 5111Belmont W A 6104 Australia F +61 8 9477 5211

Postal: PO Box 808, [email protected] WA 6985 www.gpxsurveys.com.au


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APPENDIX A: LOCATED DATA FORMAT AND PROCESSINGSPECIFICATIONS

Magnetic and Radiometric Data Description File

Project GEOSCIENCE AUSTRALIA MAG/SPEC SURVEY

Survey area KIMBERLEYSLocated data type 0.1 Second FINAL MAGNETIC Data

Surveyed by GPX AIRBORNE PTY LTD.

Job number 2289

Processed by GPX AIRBORNE PTY LTD.

Creation date October 2008

SURVEY SPECIFICATIONS

Survey flown January - October 2008Traverse line spacing 400 metres

Traverse line direction 000-180 degrees

Tie line spacing 4000 metres

Tie line direction 090-270 degrees

Survey height 60 metres

LOCATED DATA FORMAT

Variable Units Undefined From To Format


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the GPS height.

Diurnal magnetic variations have been removed.

System parallax of 1.6 fiducial has been removed.

Tie-line levelling has been applied.

Microlevelling has been applied.

A base value of 50730 nT has been added to the data.

Radiometric Channel Data Description File

Project GEOSCIENCE AUSTRALIA MAG/SPEC SURVEY

Survey area KIMBERLEYS

Located data type 1 Second FINAL RADIOEMTRIC Data

Surveyed by GPX AIRBORNE PTY LTD.

Job number 2289

Processed by GPX AIRBORNE PTY LTD.

Creation date October 2008

SURVEY SPECIFICATIONS

Survey flown January - October 2008

Traverse line spacing 400 metres

Traverse line direction 000-180 degrees

Tie line spacing 4000 metres

Tie line direction 090-270 degrees

Survey height 60 metres


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the area boundary.

The local projection is a UTM projection based on the

GDA94 spheroid with a central meridian of 129 East degrees.


RADIOMETRIC DATA

Raw channel data provided has been energy calibrated

NASVD has been applied to channel data prior to windowing


Height attenuated to 60m AGL

Airborne radon has been removed

AIRCRAFT BACKGROUND UNITS

Total Count 124.61 cps

Potassium 23.96 cps

Uranium 3.33 cps

Thorium 1.26 cps

COSMIC STRIPPING RATIOS

Total Count 0.790752Potassium 0.046416

Uranium 0.036223

Thorium 0.043527

COMPTON STRIPPING RATIOS

alpha 0.2448

beta 0.4241

gamma 0.7580

a 0.0589

HEIGHT ATTENUATION COEFFICIENT


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Project 2289, Geoscience Australia, Airborne Magnetic and Radiometric Survey, South Kimberley, WAPage 54 of 87

APPENDIX B: WEEKLY PRODUCTION SUMMARY


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2289 GA Kimberley Logistics Report

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