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    			  Thomson Aviation Pty. Ltd.                     
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   			GEOPHYSICAL SURVEY DATA REPORT
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							Date : 2nd April 2012


   This readme file describes the equipment and specifications of a geophysical
   airborne survey conducted by Thomson Aviation Pty. Ltd. 
   The readme also summarises the data processing parameters and procedures used.

   
 
   
   CLIENT DETAILS 
   ---------------    
  Company Flown by :  Thomson Aviation Pty. Ltd.
  Company Processed:  Thomson Aviation Pty. Ltd.
  Client           :  Stella Resources
  Company Job      :  Thomson 12002
  
  Total Survey Dist:  302 Km
  

  AIRBORNE SURVEY EQUIPMENT:
  -------------------------
  
  Aircraft                         : JetRanger 
  Magnetometer                     : Geometrics G822A
  Magnetometer Resolution          : 0.001 nT
  Magnetometer Compensation        : Post Flight
  Magnetometer Sample Interval     : 10 Hz
  Data Acquisition                 : GeOZ Model 2010
  Spectrometer                     : 1 x Radiation Solutions RS 400
  Crystal Size                     : 16 lt downward array
  Spectrometer Sample Interval     : 1 Second 
  GPS Navigation System            : Novatel OEMV-1VBS GPS Receiver
  
  
  AIRBORNE SURVEY SPECIFICATIONS
  ------------------------------
 
  
  Area: SE of   Borroloola
 
  Flight Line Direction            :    97 - 277  degrees
  Flight Line Separation           :          25  metres
  Tie Line Direction   		   :     0 - 180  degrees
  Tie Line Separation              :         250  metres
  Terrain Clearance                :          35  metres (MTC)
  Survey flown                     :         Mar  2012

  DATUM and PROJECTION
  --------------------
  
  Datum 			   :  Geodetic Datum of Australia 94.  GDA94
  Projection			   :  Map Grid of Australia.  MGA
  Zone				   :  Zone 55
          
  
  RADIOMETRIC PROCESSING PARAMETERS:
  ----------------------------------------
   
                      Tot.Count    Potassium   Uranium     Thorium
  Arcft Bkg           238.50       23.25       11.56       2.78
  Cosmic Bkg          1.4769       0.0840      0.0765      0.0558
  Height Attn         0.007434     0.009432    0.008428    0.00751 
 
  CPS to equivalents  50.06        204.43      17.882      10.155  (at 40 meters ground clearance)
  
  
  RADIOMETRIC STRIPPING RATIOS:
  ------------------------------

    		Alpha = 0.276		a = 0.048  
		Beta = 0.418		b = 0.003 
		Gamma = 0.759		g = 0.001 


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				DATA PROCESSING   : MAGNETIC DATA
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   MAGNETIC PROCESSING FLOW
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The final magnetic data processing was performed using the following processing flow:
	-  Aircraft magnetic data QC
	-  Diurnal magnetic data QC
	-  System parallax removal
	-  Diurnal variation removal and addition of the mean diurnal base value
	-  IGRF removal and addition of mean IGRF value.
	-  levelling using polynomial Tie line levelling, 
	-  Micro levelling if required
	-  Reduction to the pole.
	-  Gridding using Minimum Curvature algorithm 


MAGNETIC QUALITY CONTROL
------------------------
The processing of the magnetic data firstly involved the routine quality control in the field 
of both the aeromagnetic and diurnal data during the acquisition phase.  Any data found not 
meeting the required specifications were reflown.  


MAGNETIC PARALLAX CORRECTION
----------------------------
The total magnetic intensity aircraft data was firstly corrected for the effects of system 
parallax.  The parallax parameters were determined and checked from the results of opposing 
test line flights.


MAGNETIC DIURNAL CORRECTION
---------------------------
The base station magnetometer data was edited and merged into the main database. The 
aeromagnetic data was corrected for diurnal variations by subtracting the observed magnetic 
base station deviations.  There were no magnetic storms recorded by the diurnal monitoring 
station during the survey. The mean value was then added back to the data.  


MAGNETIC IGRF CORRECTION
------------------------
The data was corrected for the regional gradient of the International Geomagnetic Reference 
Field (IGRF).      The IGRF was calculated for every point along the lines with respect to
GPS height using the IGRF Model for 2010 with secular variation applied.      The mean IGRF 
value was then added back to the data.


MAGNETIC PROFILE LEVELLING
--------------------------
The magnetic traverse line data was then statistically levelled from the tie line data using 
Intrepid polynomial levelling.   The steps involved in the tie line levelling were as 
follows:  

	-    A primary tie line was chosen as a reference tie.
	-    All other ties were levelled to this tie line using 1st degree polynomial adjustment.
	-    lines were adjusted individually to minimize crossover differences, using 2nd degree   
     	     polynomial adjustments.

Any residual flight line effects were removed using Intrepid micro levelling techniques and 
the resultant line data saved as a separate field.


MAGNETIC GRIDDING
-----------------
The data was gridded to a cell size of 20% of line spacing using Minimum Curvature with 5m cell size.



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			DATA PROCESSING   : RADIOMETRIC DATA
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    RADIOMETRIC PROCESSING FLOW 
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Radiometric data processing consists of the following processing flow:


	Full spectrum 256 channel Overview:


	- Noise Adjusted Singular Value Deconvolution (NASVD) noise reduction 
	  (First 8 Principal Components)
	- Dead Time correction 
	- Energy  calibration  
	- Cosmic and Aircraft background Removal.
	- Radon background Removal 
	- Extraction of IAEA Window data


	Windowed data processing Overview:

	- Compton Stripping correction.
	- Height Attenuation correction using IAEA coefficients. 
	- Gridding

The specific processing steps are described below:


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       256 CHANNEL PROCESSING
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NASVD Noise Reduction:
---------------------
Noise-Adjusted Singular Value Decomposition (NASVD) Smoothing.   Correction of the radiometric 
data involved the reduction of the 256 channels of raw gamma spectrometer data using Noise-Adjusted
Singular Value Decomposition (NASVD) noise reduction method.  The signal to noise ratio of the 
multi channel spectra can be substantially enhanced using Noise-Adjusted Singular Value 
Decomposition (NASVD) as described by Hovgaard and Grasty (1997), Schneider (1998) and Minty (1998).  
This method involves a general linear transformation of groups of spectra (a whole line or flight), 
using NASVD to compute the different spectral shapes that make up the measured multi-channel 
spectra.  New multi-channel spectra are created by recombining the statistically significant 
spectral components.  Each spectral component contributes an unequal amount to the features 
observed in the measured multi-channel spectrum, until a point is reached where the spectral 
components represent only noise.

The 1st spectral component is the spectral shape that represents most of the features in the 
measured multi-channel spectra.  The 2nd spectral component represents those features not 
described by the 1st spectral component, etc.  By excluding from the recombination those spectral 
components that do not represent significant features in the measured multi-channel spectra, the 
resulting reconstructed multi-channel spectra have a much larger signal to noise ratio than the 
measured multi-channel spectra.
 

Dead Time Corrections:
----------------------
The raw 256 channel spectra were corrected for spectrometer dead time using the recorded live time 
and the standard formula.
			
		N = n / (1 - t) 
	
	N	=    	corrected counts in each second;
	n	=	all counts processed in each second by the ADC; and
	t	=	the recorded dead time

Where the live time (L) is recorded, the dead time t is replaced by (1 - L).


Energy Calibration:
-------------------
Energy calibration was undertaken line by line using a maximum of 3 calibration peaks; and a 
minimum of 2 calibration peaks dependent upon their clear identification in the spectra.  The 3 
calibration peaks used were Bi 214 at 0.609 Mev, K-40 at 1.46 Mev and Tl-208 at 2.615 Mev


Cosmic and Aircraft Background Correction: 
------------------------------------------
Cosmic and aircraft background removal utilised the data recorded from a series of calibration flights 
over water.  These flight produce a normalised cosmic spectra for the system installation, together with
a 256ch spectra for the aircraft background.
The combined correction is calculated using:

	N	=	a + bC,
where:
	N	=	the combined cosmic and aircraft background in each spectral window;
	a	=	the aircraft background in the window 
	C	=	the cosmic channel count; and
	b	=	the cosmic stripping factor for the window.

The values of a and b for each window are determined from the calibration flights over the sea.  
Cosmic coefficients and aircraft background coefficients were derived using INTREPID CAL256 program. 


Atmospheric Radon: 
------------------
The influence of atmospheric radon has been minimised using the spectral ratio method described by 
Minty (1992).   However the effect of radon in the Uranium channel can be considerable; and some 
effects of the radon are visable in the character of the final processed data.   
 

Extraction of Four Standard Windows:
------------------------------------
The fully processed 256 channel spectra were reduced to the four IAEA (1991) standard windows or 
Regions of Interest (ROI):  As given by the following Energy windows and channel numbers:

	Total Count	0.41 to	2.81 Mev (channels  33 to 238)
	Potassium	1.37 to	1.57 Mev (channels 116 to 133)
	Uranium   	1.66 to	1.86 Mev (channels 140 to 158)
	Thorium   	2.41 to	2.81 Mev (channels 205 to 238)


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	WINDOW PROCESSING
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Spectral Stripping of Standard Window Data:
-------------------------------------------

Corrections for Compton stripping and height attenuation were applied to the windowed 
data using constants supplied by Radiation Solutions Inc. 
Due to scattering of gamma rays in the air, the three principle stripping ratios 
( Alpha, Beta  and  Gamma) increase with altitude above the ground:

Stripping Ratio	Increase at STP per metre
 	 Alpha   0.00049
 	 Beta    0.00065
 	 Gamma   0.00069

Following adjustment of the stripping ratios for altitude, the technique for producing the corrected 
(stripped) count rates in the potassium, uranium and thorium channels (NKC, NUC and NThC) are given 
by Grasty and Minty (1995)

The Compton coefficients for the system are given above: 
	
	
 
Height Corrections
-------------------
The stripped count rates vary exponentially with aircraft altitude.  Adjustments for variation 
in altitude were made using the formula:

	Nc	= No e^ -u(H-h)

Where 	No	= uncorrected counts,
	Nc	= count rate normalised to height H,
	h	= measured height above the ground,
	H	= nominal flight height,
	u	= attenuation coefficient for the channel being corrected.


Calculation of Effective Height
-------------------------------
The Effective Height, which is the aircraft terrain clearance corrected to Standard Temperature 
and Pressure was determined as follows:

	- Filtering of the temperature field was applied to remove spikes and smooth out the 
	  instrument noise.
	- Filtering of the barometric pressure field was applied to remove spikes and to smooth 
	  out the instrument noise.
	- Filtering of the radar altimeter was applied to remove spikes, spurious reflections from
 	  groups of tree and very narrow gullies and to smooth out the instrument noise.
	- The formula option in the spread sheet editor was used to combine the terrain clearance,
 	  pressure and temperature.

			h x P x 273
	E_height =  _____________________
			1013 x (T + 273)
	Where:

	E_height=	the effective height;
	h	=	the observed radar altitude in metres;
	T	=	the measured air temperature in degrees C;
	P	=	the barometric pressure in millibars.

Reduction to Ground Concentrations:
-----------------------------------

The fully corrected window data is then converted to effective ground concentrations by dividing 
by the conversion coefficient to produce the following equivalent concentrations for each element.
 
	Total Count	: Dose Rate
	Potassium	: Percent
	Uranium	    	: PPM
	Thorium  	: PPM


Radiometric gridding
---------------------
The data was gridded to a cell size of 20% of line spacing using Minimum Curvature with 5m cell size.


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For further information on the data processing please contact Thomson Aviation Pty. Ltd. directly.
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