Synthetic Model Testing and Titan-24 DC Resistivity Results

Synthetic Model Testing and Titan-24 DC Resistivity Results at Wheeler River An Athabasca-type Unconformity Uranium Target in Northwestern Saskatchewan, Canada KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES By: Jean M. Legault*, Quantec Geoscience Ltd. , Toronto, ON Don Carriere, Carriere Process Management Ltd. , Mississauga, ON Larry Petrie, Denison Mines Corporation, Saskatoon, SK 1

Wheeler River Case History • Survey design based on initial synthetic model testing (best approach) • Comparison of several array configurations (modeling and field application) • Presence of major powerline impacts geophysics (choice of methods) KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES • Compare 2 -D and 3 -D Inversion results (improve understanding) 2

Titan 24 DCIP & MT Overview KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 3

Common DCIP Electrode Arrays KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES Titan Pldpdp Combines Pldp-left + Pldp-right 8

TITAN DCIP ARRAY CONFIGURATIONS Titan-24 Pole-Dipole Pseudosections N=0. 5 Standard Titan spread N=0. 5 to 23. 5, a= 100 m (552 data points) Line Length 2. 4 km Current Injections inside Rx Array Note: Combines pldp & dppl data N=23. 5 N=0. 5 Line Length approx. 4. 4 km Current Injections inside & outside Rx Array KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES Extended Titan spread (adding current extensions beyond end of receiver array) N=0. 5 -33. 5, a=100 m (approx. 1032 points) N=10. 5 N=23. 5 Note: Combines pldp & dppl data N=33. 5 9

Case History: M-zone at Wheeler River KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES Commissioned by Denison Mines Corporation in JV with Cameco Corporation and Japan-Canada Uranium Ltd. April-May, 2007 10

Titan Survey Objectives • • Define DC (+/- IP) signatures associated with: a) Uranium-bearing graphitic conductor at M-Zone b) Granitic gneiss to the south-east of M-Zone c) Alteration chimney in sandstones above M-Zone • KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES Wheeler River mineralization occurs in 400 m thick Athabasca Sandstone along the Unconformity, below alteration zone that is associated with underlying basement Graphitic metapelites known as the M-Zone conductive trend. Test Titan multi-parameter capability, with emphasis on Galvanic DC Resistivity (possibly also IP) using Pole-Dipole Array, in direct comparison with Dipole-Dipole and more widely used Pole-Pole Array. • Field Surveys were preceded by 2 -D synthetic modeling study that tested for optimal array parameters (dipole size) and configurations (Pldp vs Plpl vs Dpdp array). 11

Wheeler River Location: Introduction HISTORIC NOTES § 35 km NE of Key Lake & 10 km W of Moore Lake. Wheeler River Project Moore Lake Key Lake § Originally discovered in 1980’s (UTEM followup of Airborne) but remained unexplored until recently. § Since 1980’s, major powerline through property (along BL) – impacts EM follow-up. KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 12

BASEMENT AND UNCONFORMITY HOSTED URANIUM DEPOSIT STYLES § Mineralization occurs: a) at unconformity, b) above graphite, c) with basement elevation change. M-Zone Deposit Style: ALTERATION ASSOCIATED WITH UNCONFORMITY-HOSTED URANIUM DEPOSITS Possible Targets: 1) Alteration Zone 2) Unconformity 3) Basement Graphite KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES Silicification Clay-Alteration 13

e WHEELER M-ZONE – AIRBORNE TOTAL FIELD MAGNETICS e w Po s s L 1 00 m i ed s ta t e M en ic em lit as Pe B in S t en M - ZO N E D ri e ol M R 0 200 m E N O -Z d oa llh ss ei n G nt ic e it em n s ra Ba G in KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES in rl L 1 00 S 14

BL 0 E WHEELER M-ZONE – GEOLOGIC SECTION ACROSS L 100 S M-ZONE DRILLING Overburden (<10 m) -> Manitou Falls D -> VR-205 ZM-10 ZM-11 ZM-06 0 - Ground Surface § Known Geology is based on drilling Along a Narrow Corridor, with Little Known Outside that line. Sandstone (80 -90 m thick) 380 -400 m Manitou Falls B -> Sandstone (100 -120 m thick) (70 -100 m thick) Basement Rocks -> Arkose-Anatexite (blues) Pegmatite-Granite (pink) Pelite-Graphites (grey-black) 10 0 GEOLOGIC NOTES Manitou Falls C -> Sandstone L S (10 -20 m thick) Manitou Falls A -> Plan View 200 m Uranium Minerali zed Zone - Un mity nfor co § Basement Dips Uncertain – possibly Steep Southeast § M-zone consists of DDH Intersections along Graphitic Conductor and Elevation Change in Basement Topography. 0 50 m View Looking NE 15

Case History: Wheeler River 2 -D Synthetic Modeling KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 16

GEOPHYSICAL PROPERTY MODEL for ATHABASCA-TYPE URANIUM DEPOSITS Water 100 – 2 000 m Overburden 10 - 100 k m Fault Sandstone 2 000 – 5 000 m Lake seds 100 - 500 m Contact UC Unconformity Psammitic (Felsic) Gneiss 5 - 100 k m Granite 10 - 100 k m KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES Graphitic Metapelite <1 -50 m Alteration 50 -20 000 m Metapelite 50 -1 000 m (from Witherly, 2005) 17

Titan Multi-Array DC Survey 2 D DC Forward Models 10 -10 k ohm-metres Note: 500 m (n=10) Current extensions A) Extended Titan Pole-dipole Array a=50 m / n=0. 5 -33. 5 0 500 m 50 m A-spacing UBC 2 d Synthetic Forward Model Data 3000 ohm-m 300 m - 100 m 5 ohm-m 1000 m - 2. 2 km Total array length 3000 ohm-m 2 d Reference Note: Gp response only Model at base of pseudosection, i. e. , 50 m a-spacing likely provides insufficient penetration 10 -10 k ohm-metres Note: 600 m (n=6) Current extensions B) Extended Titan Pole-dipole Array a=100 m / n=0. 5 -29. 5 0 500 m 100 m A-spacing 3000 ohm-m 1000 ohm-m 5 ohm-m 300 m - 1000 m - Note: Gp response in upper 1/3, i. e. , 150 m a-spacing possibly 300 m exceeds required penetration lacks and focus within Sandstone 2 d Reference Model Note: Gp response in middle, i. e. , 100 m a-spacing likely provides sufficient penetration and focus within Sandstone and Gp 3. 7 km Total array length 10 -10 k ohm-metres Note: 1500 m (n=10) Current extensions C) Extended Titan Pole-dipole Array a=150 m / n=0. 5 -33. 5 UBC 2 d Synthetic Forward Model Data 0 500 m 150 m A-spacing 1000 ohm-m 3000 ohm-m 100 m 5 ohm-m 6. 75 km Total array length 2 d Reference Model 18

Multi-Array Survey A) 2 D Synthetic DC Inversions Range 10 to 10 k ohm-metres 0 m - 2 d DC Resistivity Dipole-dipole Array -300 m Unconformity 500 m - Note: Dpdp provides high resolution but possibly lacks depth penetration 1000 m - B) 2 d DC Resistivity Pole-dipole Array Range 10 k to 10 ohm-metres -300 m Unconformity 0 m - 500 m - Note: Pldp provides good balance between resolution and depth penetration 1000 m - C) Range 10 to 10 k ohm-metres 0 m - 2 d DC Resistivity Pole-pole Array -300 m Unconformity 500 m - 1000 m 0 1500 m - Loke 2 d Inversions using Res 2 d. Inv (Loke and Barker, 1996) Note: Pldp provides best depth penetration but possibly lacks deep resolution 500 m 19

Case History: Wheeler River DC/IP Field Tests along L 100 S KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 20

L 1 O 00 S M L 1 00 S E N O -Z KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES E N O -Z R D A M N LI ER PO W E 0 1 km 21

Line 100 S Titan DC Survey 2 D DC/IP Pseudosections IP Phase Pseudosections Apparent Resistivity Pseudosections (Max 3 mrad error shown) (Max 10% Vp error shown) Range 10 to 10 k ohm-metres Note: Weaker DC Low and No IP high over GP N=28. 5 - ? 431 of 1091 total pts (40%) retained for Inversion 887 of 1091 total pts (81%) retained for Inversion Dipole-dipole Array (a=100 m / n=0. 5 -17. 5 / 0. 55 A avg) (a=100 m / n=0. 5 -28. 5 / 0. 55 A avg) Range 10 to 10 k ohm-metres - N=17. 5 Range 0 to 30 milliradians Note: Coincident DC Low + IP High over Gp N=33. 5 - Range 0 to 30 milliradians - N=19. 5 785 of 1166 total pts (68%) retained for Inversion 1160 of 1166 total pts (>99%) retained for Inversion Pole-dipole Array (a=100 m / n=0. 5 -33. 5 / 0. 51 A avg) (a=100 m / n=0. 5 -19. 5 / 0. 51 A avg) Range 10 to 10 k ohm-metres Note: Strong but Wide DC Low + No IP high over GP N=27. 5 - 1089 of 1150 total pts (95%) retained for Inversion Pole-Pole Array (a=100 m / n=0. 5 -27. 5 / 0. 73 A avg) 0 500 m Range 0 to 30 milliradians ? - N=17. 5 571 of 1150 total pts (50%) retained for Inversion Pole-pole Array (a=100 m / n=0. 5 -17. 5 / 0. 73 A avg) 22

Line 100 S Titan DC Survey 2 D DC Inversions A) Range 10 to 10 k ohm-metres 0 m - -400 m Unconformity 2 d DC Resistivity 500 m Dipole-dipole Array Note: Dpdp provides high resolution but lacks depth penetration 1000 m - B) 2 d DC Resistivity Pole-dipole Array Range 10 k to 10 ohm-metres 0 m - -400 m Unconformity 500 m - Note: Pldp provides best balance between resolution and penetration 1000 m - C) 2 d DC Resistivity Pole-pole Array Note: Plpl provides most depth penetration but possibly lacks resolution Range 10 to 10 k ohm-metres 0 m - -400 m Unconformity 500 m - 1000 m 0 Loke 2 d Inversions using Res 2 d. Inv (Loke and Barker, 1996) 500 m 23

Line 100 S DC, IP & MT 2 D & 3 D Inversions 3 d 2 d DC Resistivity 500 m - 1000 m - Alteration Zone G Grra ap h p hitte ie 0 m 0 m - Range 10 to 10 k ohm-metres -400 m Unconformity G Gra ran niit te C e Co on ntta act ct? ? Loke 2 d Inversions using Res 2 d. Inv (Loke and Barker, 1996 a) Loke 3 d Inversions using Res 2 d. Inv (Loke and Barker, 1996 b) Range 0 to 50 milliradians 0 m 0 m Alteration Zone? 500 m - 1000 m - G Gra ran niit te e Gr Ga rap phh itiee t? 3 d IP Chargeability 2 d Note: 2 d DC 3 d indicates suggests W-dip steeper dip for M-zone -400 m Unconformity Note: 3 d IP Note: M-zone resolves M-zone poorly resolved C Co on ntta act ct? ? Loke 2 d Inversions using Res 2 d. Inv (Loke and Barker, 1996 a) 3 d 1996 b) Range 10 to 10 k ohm-metres 0 m - e hit 1000 m - -400 m Unconformity G 500 m - Gr ap 2 d PW MT TM-TE Resistivity Alteration Zone ra ni Note: M-zone alteration appears well resolved but conductor dip and contrast differs w DC te -M et as ed im en 1500 m - t. C on ta ct ? Quantec PW 2 dia Inversions based on algorithm by de Lugao and Wannamaker (1996) 0 500 m

WHEELER M-ZONE – 3 -D VOLUME of 2 -D SMOOTH DC RESISTIVITY A) Z=20 m Z=1300 m Z=1250 m Z=1200 m Z=1150 m Z=1100 m Z=1050 m Z=1000 m Z=700 m Z=650 m Z=600 m Z=550 m Z=500 m Z=450 m Z=400 m Z=350 m Z=300 m Z=250 m Z=200 m Z=150 m Z=100 m Z=950 m Z=900 m Z=850 m Z=800 m Z=750 m Z=50 m Note: Powerline Visible in Near Surface Note: Migration of Graphite Note: Alteration Visible Conductive Zone to NW in Basement 100 m above UC KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 26

WHEELER M-ZONE – 3 -D VOLUME of 2 -D SMOOTH CHARGEABILITY Z=1400 m Z=900 m Z=500 m Z=100 m Z=20 m Z=1100 m Z=300 m Z=700 m Note: PL+Road+Noise Visible in Near Surface Note: Alteration in IP Graphite IP High? Note: Graphite IP High? low above High? Note: Graphite IPUC? Note: Graphite IP High? KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 27

WHEELER M-ZONE – 3 -D VOLUME of 3 -D SMOOTH RESISTIVITY Z=500 m Z=1300 m Z=900 m Z=1400 m Z=300 m Z=100 m Z=20 m Note: Graphite well Note focused DC NW Absence of resistivity resolved in basement Note: Powerline of NW Note: in Gp signature migration Absence correlates low 100 m above UC migration insurface DC low with near Gp signature KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 28

WHEELER M-ZONE – 3 -D VOLUME of 3 -D SMOOTH CHARGEABILITY Z=200 m Z=1400 m Z=900 m Z=1300 m Z=500 m Z=300 m Z=100 m Note: Well defined Note Well Note: Layer-like IP-High Note: widespread IP presence of. DC high along defined low Note: Well DC IP high along. IP low zoneon sandstone? in north defined (except in sandstone lines) layer IP high along DC low (also on north lines) KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 29

Study Findings • Field surveys corroborated our initial 2 -D DC synthetic modeling studies, i. e. , Dpdp offered best resolution but poorest penetration; Plpl had greatest penetration but poorer resolution; Pldp had better combination of resolution, penetration and economy. • DC resistivity data quality and survey productivity greatly improved current injections (>0. 5 A avg), thanks to more powerful GDD Tx – suggests >2 -3 season capability for DC/IP. • • KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES DC resistivity results do not appear to be significantly hindered by powerline effects, but IP significantly more affected (acceptable). MT data quality excellent – not hindered by ground contacts or Powerline effects – confirms all season capability. Multi-parameter DC-IP-MT results show remarkable similarities and contrasting behaviour (i. e. , DC vs MT; 2 D vs 3 D). • • • 3 -D inversions simplify, improve understanding of responses. Coincident DC+MT resistivity low and IP high confirmed over graphite > additional tool for geologic mapping & discrimination. 30

Titan-24 DC Resistivity Results at Wheeler River Thank You DENISON MINES Corporation Toronto, ON KEGSEXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES CAMECO Corporation Saskatoon, SK Japan-Canada Uranium Tokyo, Japan Toronto, ON 31