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Ministry of Energy Mines and Responsible for Core Review

The MapPlace - Quesnel Geophysics

(BCMEM OF 2004-9 / GSC OF 4615, 4616 & 4617; BCMEM OF 2004-10/ BCMEM OF 2005-16 / GSC OF 4619)

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Details: Quesnel Trough Geophysics covers four geophysical surveys: 1993 Quesnel and 2003 Horsefly surveys are represented in BCMEM Open File 2004-9, GSC OF 4615 and GSC OF 4616; 2003 Imperial Metals Corp. Mount Polley survey is represented in BCMEM Open File 2004-10 and GSC OF 4619; 2004 Tisdall Lake survey is represented in BCMEM Open File 2005-16. The files are also available for download in georeferenced TIF and PNG formats and GeoSoft gridded data (.grd) format.  The 2003 surveys, including the Toodoggone Geophysics, were posted to MapPlace March 26, 2004.  Bulletin 97 (PDF) describes the geology and mineral deposits of the Quesnel River - Horsefly Map Area, Central Quesnel Trough, British Columbia. The 2004 survey was posted to MapPlace April 8, 2005.

 

July 31, 2006: Additional surveys conducted in 2004-2005 resulted in new compilations shown on the 2005 Geophysical Surveys Map.

 

A 1:250 000 scale geophysical map of Quesnel Lake, compiled using survey data acquired between 1991 and 2005, is available as Geological Survey of Canada, Open File 5295; free Download from GEOSCAN.

 

View Quesnel Geophysics Map


 

Geophysics Map


How the Magnetic and Radiometric Maps Can be Used:

Multiparameter (gamma-ray, magnetic) geophysical surveys are useful in mineral exploration and bedrock mapping studies. In the Quesnel Trough, these surveys are particularly useful in exploring for alkalic porphyry Cu-Au porphyry deposits like Mt. Polley, or related deposits like QR. The potassium, potassium/thorium, magnetic total field and magnetic vertical gradient maps can be used to help identify potassic alteration and magnetite enrichment/depletion zones associated with copper-gold mineralization, and also help in mapping lithologies and structures.

Survey Summary:

The 1993 Mount Polley survey was flown with the GSC Sky-van fixed wing aircraft. Flight lines were flown in an east-west direction with a line-spacing averaging 500 m. The data was released in 1995 as GSC Open File 2802 by R.B.K. Shives et al.


HORSEFLY MULTISENSOR GEOPHYSICAL SURVEY
Open File 2004-9 / GSC OF 4615GSC OF4616
Helicopter-borne gamma ray spectrometric and magnetic total field geophysical survey, Horsefly Area, British Columbia
(Parts of NTS 93A/3,5,6,11)
Shives, R.B.K., Carson, J.M., Ford, K.L., Holman, P.B., Cathro, M.

In 2003 the Geological Survey of Canada conducted a multisensor (gamma-ray spectrometric, magnetic total field) helicopter-borne geophysical survey in the Horsefly area, British Columbia, Canada. Flight lines were oriented NE-SW, spaced at 500 m intervals. The survey was flown under contract, by Fugro Airborne Surveys. Results are combined with the previously flown 1993 Mount Polley Survey (93A/12). The survey was funded by the British Columbia and Yukon Chamber of Mines’ “Rocks to Riches” Program. This data was published as GSC OF 4615 & GSC OF 4616 in 2004 and to MapPlace as BCMEM Open File 2005-9 on March 26, 2004.

 

IMPERIAL METALS CORP. MOUNT POLLEY 2003 MULTISENSOR GEOPHYSICAL SURVEY
Open File 2004-10 / GSC OF 4619
Helicopter-borne gamma ray spectrometric and magnetic total field geophysical survey,
Imperial Metals Corporation’s Mount Polley Mine area, British Columbia
(Part of NTS 93A/12)

Shives, R.B.K., Carson, J.M., Ford, K.L., Holman, P.B., Cathro, M.

In 2003 Imperial Metals Corporation conducted a multisensor (gamma-ray spectrometric, magnetic total field) helicopter-borne geophysical survey over the Mount Polley Mine area, British Columbia, Canada. Flight lines were oriented east-west, spaced at 100 m intervals. The survey was flown under contract, by Fugro Airborne Surveys. The survey was funded by Imperial Metals Corporation and the British Columbia & Yukon Chamber of Mines "Rocks to Riches" Program.  This data was published as GSC OF 4619 in 2004 and to MapPlace as BCMEM Open File 2005-10 on March 26, 2004.

 

TISDALL LAKE 2004 MULTISENSOR GEOPHYSICAL SURVEY
Open File 2005-16
Helicopter-borne gamma ray spectrometric and magnetic total field geophysical survey, Tisdall Lake area, British Columbia
(Parts of NTS 92P/15; 93A/2, 3,6,7)
Shives, R.B.K., Carson, J.M., Dumont, R., Holman, P.B., Yeager, D., Geological Survey of Canada

In 2004 the Geological Survey of Canada conducted a multisensor (gamma-ray spectrometric, magnetic total field) helicopter-borne geophysical survey in the Tisdall Lake Area, southeast of Mount Polley, British Columbia, Canada. Flight lines were oriented NE-SW, spaced at 250 m intervals. The survey was flown under contract by Fugro Airborne Surveys. Funding was provided by Amarc Resources Ltd.  Support for the Geological Survey of Canada’s Radiation Geophysics Section, acting as the Scientific Authority for the survey, was provided under Natural Resources Canada – Earth Sciences Sector’s Northern Resources Development Program.

 

This data was published to MapPlace as BCMEM Open File 2005-16 on April 8, 2005. A full product release (in late spring 2005) will be made by the Geological Survey of Canada as a series of Open Files, including printed colour maps, images of the printed maps in PDF format, and digital line and grid data.

 

Analogue and digital products include data for eight radiometric and two magnetic parameters:

MapPlace Layer Themes Horsefly
OF 2004-9
PDF Themes Files
see Note 1
Imperial Mount Polley
OF 2004-10
PDF Themes Files
Tisdall Lake OF 2005-16
PDF Themes Files
MTF - Magnetic total field (nT) H_mtf.pdf (2.3MB)    
CVG - Calculated magnetic vertical gradient (computed, nT/m) H_cvg.pdf (2.7MB)    
POT - Potassium (K, %) H_pot.pdf (2.6MB)    
URA - equivalent Uranium (eU, ppm) H_ura.pdf (2.8MB)    
THO - equivalent Thorium (eTh, ppm) H_tho.pdf (2.7MB)    
ADRN - Natural air absorbed dose rate (ADRN, nGy/h) H_adrn.pdf (2.6MB)    
RUT - equivalent Uranium/equivalent Thorium (eU/eTh) H_rut.pdf
(2.7MB)
   
RUK - equivalent Uranium/Potassium (eU/K, ppm/%) H_ruk.pdf (2.7MB)    
RTK - equivalent Thorium/Potassium (eTh/K, ppm/%) H_rtk.pdf
(2.6MB)
   
TER - Ternary radioelement map (K, eU, eTh) H_ter.pdf
(2.4MB)
   
1:250K Scale Geology, Mineral Occurrences & Titles H_geology.pdf (1.0MB)    
All Themes in one file (11 by 17 images) H_geophysics.pdf (9.8MB) I_geophysics.pdf (5.1MB)  
GSC Open Files 4617 Final Product Release Final Product Release Final Product Release
Plot sized PDF 1:50K, 1:250K 1:20K  
File Downloads Zip Files Zip Files Zip Files
Georeferenced TIFF files (UTM Zone 10 NAD 83) H_tif_Z10.zip (2.1MB) I_tif_Z10.zip (2.0MB) Tis_tif_Z10.zip (2.0MB)
Georeferenced TIFF files (Albers NAD 83) H_tif_AL.zip (1.9MB) T_tif_AL.zip (1.9MB) Tis_tif_AL.zip (2.0MB)
Georeferenced PNG files (UTM Zone 10 NAD 83) H_png_Z10.zip (1.1MB) I_png_Z10.zip (1.0MB) Tis_png_Z10.zip (1.3MB)
Georeferenced PNG files (Albers NAD 83) H_png_AL.zip (2.3MB) I_png_AL.zip (1.0MB) Tis_png_AL.zip (1.3MB)
Original GSC SurView data files for viewing and printing only (.gri & .grx) H_gri.zip (3.9MB) I_gri.zip (3.8MB)  
Original GSC Geosoft gridded data format (.grd), see Note 2 H_grid.zip  (4.3MB) I_grid.zip (3.9MB) Tis_grid.zip (5.8MB)
Original GSC Ternary data (.bil), see Note 3 H_ternary.zip (1.0MB) I_ternary.zip (1.0MB)  
1993 Quesnel PNG files (Albers NAD 83) Q geophysics.zip(7.7MB)    

Note 1: The PDF maps were created from MapPlace using the Rasterize print job option to eliminate the black background. The TIF and PNG download images include the geophysical information without topographic base information.

Note 2: Example from Gary Lustig on using the Imperial gridded download files to produce these Sample Magnetic Images (PDF 2.1MB). Download the magnetic grid files and created Geotiffs in Geosoft's Oasis Montaj. This free version creates very good colour and grey scale shadow plots using the default illumination (045 azm and +45 deg).  But to get a good colour shadow plot, combine the two images either in ArcGIS, MapInfo or in an image program, making the top colour layer partially transparent.  The contours were generated using Geosoft Target, an add-in to ArcGIS. The Geotiffs can be any resolution you want - the Sample Images are very low resolution compared to the Geotiffs which are ~20Mb each.

Note 3: To display the Ternary images using Geosoft's Oasis Montaj the following instructions will yield the best results.

bullet In Oasis, select the grid pulldown menu.
bullet select Display grid as Ternary image
bullet Colour model must = RGB
bullet Colouring method must = Linear
bullet The three colour component files must be opened as Files of Type BIL with *.hdr header.
bullet Red-Cyan = TERURA_C.BIL
bullet Green-Magenta - TERPOT_M.BIL
bullet Blue-Yellow = TERTHO_Y.BIL
bullet Shading grid = nothing
bullet Shading grid colouring method = Linear
bullet To display the triangular Ternary Legend select Display grid - Ternary Legend
bullet Colour model must = CMY

If these instructions are not followed, the resulting image will be a three colour image but not the intended GSC style image. These ternary images should not be treated as data. The derivation of the colours involves multiple histogram equalizations.

Legend:

K - potassium, i.e. K40 (units: %)
eU - equivalent uranium concentration by weight (the spectrometer directly measures Bi214, that is an indirect measure of uranium) (units: ppm)
eTh - equivalent thorium concentration by weight (the spectrometer directly measures Tl208, that is an indirect measure of thorium) (units: ppm)
Total Count - all counts from 400 to 3000 keV. (units: cps or uR/h)
Natural Exposure - computed from K (%), eU (ppm), eTh (ppm) concentrations:
Exposure = 1.505 K + 0.625 eU + 0.31 eTh (uR/h)
(Grasty et al, 1984) 'Exposure' is different from the traditional 'Total Count', in that it excludes radiation from man-made contaminants.
Natural Air Absorbed Dose Rate - computed from K (%), eU (ppm), eTh (ppm) concentrations:
Absorbed Dose Rate = 13.08 K + 5.43 eU + 2.69 eTh (nGy/h) 'Natural Air Absorbed Dose Rate' is different from the traditional 'Total Count', in that it excludes radiation from man-made contaminants.
eU/eTh, eU/K, eTh/K - ratios of K, eU, eTh that are useful for interpretation

Units:

nT - unit of magnetic total field (nano Tesla)
ppm - unit of concentration by weight (part per million), used for eU (uranium) and eTh (thorium)
% - for potassium (K40): unit of concentration by weight
Ur - unit of radioelement concentration by weight
(1 Ur is defined as the total count rate from 1 ppm uranium in equilibrium)
µR/h - unit of Exposure (micro Roentgen/hour)
nGy/h - unit of Natural Air Absorbed Dose Rate (nano Gray/hour)

For information contact

BC Geological Survey
Telephone: (250) 952-0372 Fax: (250) 952-0381
Website: http://www.empr.gov.bc.ca/MINING/GEOSCIENCE/Pages/default.aspx* * * FINAL PRODUCT RELEASE * * *

The Geological Survey of Canada and the BC Ministry of Energy and Mines has made the multisensor geophysical survey data for the Horsefly-Mount Polley and Imperial Mount Polley surveys available in a variety of digital and printed formats.  The Tisdall Lake survey will be available in late spring of 2005:

 

1. Available from GSC offices in Vancouver & Ottawa on demand

bullet 1:50 000 scale colour interval, hardcopy maps (1:20 000-scale for the Imperial Metals Corp Mt Polley 2003 survey).
bullet 1:250 000 scale colour interval hardcopy maps

2. Available from GSC Offices in Vancouver and Ottawa or download from MapPlace:

bullet Plot sized digital images of colour interval maps on CD-ROM in Portable Document Format (PDF).
Horsefly GSC Open File
4615 and 4616

Read Me

1:50K 1:250K
MTF - Magnetic total field (nT) 4615_09.pdf (6.3MB) 4616_09.pdf (2.0MB)
CVG - Calculated magnetic vertical gradient (computed, nT/m) 4615_10.pdf (8.5MB) 4616_10.pdf (2.5MB)
POT - Potassium (K, %) 4615_02.pdf (7.6MB) 4616_02.pdf (2.4MB)
URA - equivalent Uranium (eU, ppm) 4615_03.pdf (8.2MB) 4616_03.pdf (2.6MB)
THO - equivalent Thorium (eTh, ppm) 4615_04.pdf (7.7MB) 4616_04.pdf (2.5MB)
ADRN - Natural air absorbed dose rate (ADRN, nGy/h) 4615_01.pdf (7.6MB) 4616_01.pdf (2.4MB)
RUT - equivalent Uranium/equivalent Thorium (eU/eTh) 4615_05.pdf (8.4MB) 4616_05.pdf (2.5MB)
RUK - equivalent Uranium/Potassium (eU/K, ppm/%) 4615_06.pdf (8.0MB) 4616_06.pdf (2.4MB)
RTK - equivalent Thorium/Potassium (eTh/K, ppm/%) 4615_07.pdf (7.6MB) 4616_07.pdf (2.4MB)
TER - Ternary radioelement map (K, eU, eTh)  4615_08.pdf (7.6MB) 4616_08.pdf (2.3MB)
**Also see Analogue and Digital Products for MapPlace layer themes and file downloads.
Imperial Mt. Polley GSC Open File 4619 

Read Me

1:20K  
MTF - Magnetic total field (nT) 4619_09.pdf (2.8MB)  
CVG - Calculated magnetic vertical gradient (computed, nT/m) 4619_10.pdf (4.6MB)  
POT - Potassium (K, %) 4619_02.pdf (3.2MB)  
URA - equivalent Uranium (eU, ppm) 4619_03.pdf (4.6MB)  
THO - equivalent Thorium (eTh, ppm) 4619_04.pdf (4.3MB)  
ADRN - Natural air absorbed dose rate (ADRN, nGy/h) 4619_01.pdf (3.2MB)  
RUT - equivalent Uranium/equivalent Thorium (eU/eTh) 4619_05.pdf (5.0MB)  
RUK - equivalent Uranium/Potassium (eU/K, ppm/%) 4619_06.pdf (4.4MB)  
RTK - equivalent Thorium/Potassium (eTh/K, ppm/%) 4619_07.pdf (4.0MB)  
TER - Ternary radioelement map (K, eU, eTh) 4619_08.pdf (3.7MB)  
**Also see Analogue and Digital Products for MapPlace layer themes and file downloads.
Tisdall Lake GSC Open File pending

 

Spring 2005  
MTF - Magnetic total field (nT)    
CVG - Calculated magnetic vertical gradient (computed, nT/m)    
POT - Potassium (K, %)    
URA - equivalent Uranium (eU, ppm)    
THO - equivalent Thorium (eTh, ppm)    
ADRN - Natural air absorbed dose rate (ADRN, nGy/h)    
RUT - equivalent Uranium/equivalent Thorium (eU/eTh)    
RUK - equivalent Uranium/Potassium (eU/K, ppm/%)    
RTK - equivalent Thorium/Potassium (eTh/K, ppm/%)    
TER - Ternary radioelement map (K, eU, eTh)    
**Also see Analogue and Digital Products for MapPlace layer themes and file downloads.


3. Available only from the Radiation Geophysics Section in Ottawa, on demand
.

bullet Customized geophysical survey digital data on CD-ROM in a user-compatible format.