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

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 2 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) Compare 2-D and 3-D Inversion results (improve understanding)

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 3 Titan 24 DCIP & MT Overview

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 4 Titan-24 System History First commercial 24 bit A/D, MT & DCIP Distributed Acquisition System (DAS) – by Quantec Geoscience Ltd in Modeled after Mount Isa Mines (MIM) Exploration MIM-DAS System, conceived in 1994 (Sheard, ASEG-1998, Hobart, AU). First Titan-24 Survey Commissioned by Barrick in 2000, along Carlin Trend, SW US. First Titan Surveys Undertaken in Canada in 2001 by Noranda Exploration in Bathurst Camp, NB. First Titan Surveys Undertaken in Athabasca Basin in 2005 (Legault, SEG-2006, New Orleans, LA). Wheeler River Survey Undertaken in April-July, 2007 on behalf of Denison Mines in JV Cameco and JCU

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 5 TITAN-24 Interpretation  2D-3D DCIP & MT Inversion Capability  Unconstrained (No Geologic Reference)  Constrained (Geologic Reference)  Commercial code (UBC & Loke 2d & 3d DC/IP)  Proprietary code (PW 2d MT & MTDC2D 2d Joint MT+DCIP) Distributed Acquisition System (>50 channels)  High resolution 24 bit A/D sampling  Multi-Parameter Measurements  DC Resistivity & Induced Polarization  Tensor Audiomagnetotelluric Resistivity Digital Signal Processing  Full waveform data (DCIP)  Smart Stacking (DCIP)  Spectral Decay Curve Fitting (DCIP)  Telluric Cancellation (DCIP)  Remote-referencing (MT) Titan-24 System Main Components

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES Processing and Interpretation Flow DAS = Time series DSP = High Quality Data Interpretation = 2-D & 3-D Inversion Models

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 7 2 Channel AM Battery Typical Station Set-up Titan-24 Distributed Acquisition System Titan - 24 Distributed Acquisition System LAN Link to Logging Truck 50m 100m infinity current electrode (fixed) >5-10 km DAY TIME = DC/IP SURVEY B x B y Remote Magnetometer site >20 km x B y Base magnetometer Site NIGHT TIME = MT SURVEY

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

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 9 Standard Titan spread N=0.5 to 23.5, a= 100m (552 data points) Line Length 2.4 km Current Injections inside Rx Array N=0.5 N=23.5 Extended Titan spread (adding current extensions beyond end of receiver array) N= , a=100m (approx points) Line Length approx. 4.4 km Current Injections inside & outside Rx Array N=0.5 N=23.5 N=10.5 N=33.5 Titan-24 Pole-Dipole-Dipole Pseudosections TITAN DCIP ARRAY CONFIGURATIONS Note: Combines pldp & dppl data

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

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 11 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 Wheeler River mineralization occurs in 400m 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. Titan Survey Objectives 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).

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

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

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 14 WHEELER M-ZONE – AIRBORNE TOTAL FIELD MAGNETICS 0 200m Road M-ZONE Powerline Drillholes Granitic Gneiss in Basement Pelitic Metasediments in Basement L100S

ZM-06 ZM-10 ZM-11 VR Ground Surface Overburden ( Manitou Falls C -> Sandstone (80-90m thick) Manitou Falls B -> Sandstone ( m thick) Manitou Falls A -> Sandstone (70-100m thick) Manitou Falls D -> (10-20m thick) - Unconformity m WHEELER M-ZONE – GEOLOGIC SECTION ACROSS L100S Basement Rocks -> Arkose-Anatexite (blues) Pegmatite-Granite (pink) Pelite-Graphites (grey-black) Uranium Mineralized Zone 0 50m View Looking NE GEOLOGIC NOTES L 100S BL 0E M-ZONE DRILLING 0 200m Plan View  M-zone consists of DDH Intersections along Graphitic Conductor and Elevation Change in Basement Topography.  Basement Dips Uncertain – possibly Steep Southeast  Known Geology is based on drilling Along a Narrow Corridor, with Little Known Outside that line.

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

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

300m m - UBC 2d Synthetic Forward Model Data 2d Reference Model Note: 1500m (n=10) Current extensions C) Extended Titan Pole-dipole Array a=150m / n= km Total array length 150m A-spacing 10-10k ohm-metres 0 500m 300m m - UBC 2d Synthetic Forward Model Data 2d Reference Model B) Extended Titan Pole-dipole Array a=100m / n= Note: 600m (n=6) Current extensions 3.7 km Total array length 100m A-spacing 10-10k ohm-metres 0 500m 3000 ohm-m 300m m - UBC 2d Synthetic Forward Model Data 2d Reference Model Note: 500m (n=10) Current extensions A) Extended Titan Pole-dipole Array a=50m / n= km Total array length 50m A-spacing 10-10k ohm-metres 0 500m 1000 ohm-m 3000 ohm-m 5 ohm-m 100m 1000 ohm-m 3000 ohm-m 5 ohm-m 100m 1000 ohm-m 5 ohm-m 100m 3000 ohm-m Titan Multi-Array DC Survey 2D DC Forward Models Note: Gp response only at base of pseudosection, i.e., 50m a-spacing likely provides insufficient penetration Note: Gp response in middle, i.e., 100m a-spacing likely provides sufficient penetration and focus within Sandstone and Gp Note: Gp response in upper 1/3, i.e., 150m a-spacing possibly exceeds required penetration lacks and focus within Sandstone

2d DC Resistivity Pole-pole Array Range 10 to 10k ohm-metres 500m m - 0m - C) 0 500m 1500m - Loke 2d Inversions using Res2dInv (Loke and Barker, 1996) 2d DC Resistivity Dipole-dipole Array 500m m - Range 10 to 10k ohm-metres 0m - A) -300m Unconformity 2d DC Resistivity Pole-dipole Array 500m m - 0m - B) Range 10k to 10 ohm-metres Multi-Array Survey 2D Synthetic DC Inversions -300m Unconformity Note: Dpdp provides high resolution but possibly lacks depth penetration Note: Pldp provides good balance between resolution and depth penetration Note: Pldp provides best depth penetration but possibly lacks deep resolution

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 20 Case History: Wheeler River DC/IP Field Tests along L100S

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 21 ROAD M-ZONE 0 1km POWERLINE L100S

Range 10 to 10k ohm-metres Pole-Pole Array Pole-pole Array Range 0 to 30 milliradians (a=100m / n= / 0.73A avg)(a=100m / n= / 0.73A avg) N= N=17.5 Range 10 to 10k ohm-metres Pole-dipole Array Range 0 to 30 milliradians (a=100m / n= / 0.51A avg) (a=100m / n= / 0.51A avg) N= N=19.5 Line 100S Titan DC Survey 2D DC/IP Pseudosections 0 500m 1160 of 1166 total pts (>99%) retained for Inversion 785 of 1166 total pts (68%) retained for Inversion 1089 of 1150 total pts (95%) retained for Inversion 571 of 1150 total pts (50%) retained for Inversion Apparent Resistivity Pseudosections (Max 10% Vp error shown) IP Phase Pseudosections (Max 3mrad error shown) Dipole-dipole Array (a=100m / n= / 0.55A avg) (a=100m / n= / 0.55A avg) Range 10 to 10k ohm-metres Range 0 to 30 milliradians N= N= of 1091 total pts (81%) retained for Inversion 431 of 1091 total pts (40%) retained for Inversion ? ? Note: Coincident DC Low + IP High over Gp Note: Weaker DC Low and No IP high over GP Note: Strong but Wide DC Low + No IP high over GP

2d DC Resistivity Pole-dipole Array 500m m - 0m - B) Range 10k to 10 ohm-metres -400m Unconformity 2d DC Resistivity Dipole-dipole Array 500m m - Range 10 to 10k ohm-metres 0m - A) 2d DC Resistivity Pole-pole Array Range 10 to 10k ohm-metres 500m m - 0m - Loke 2d Inversions using Res2dInv (Loke and Barker, 1996) C) -400m Unconformity 0 500m Line 100S Titan DC Survey 2D DC Inversions Note: Dpdp provides high resolution but lacks depth penetration Note: Pldp provides best balance between resolution and penetration Note: Plpl provides most depth penetration but possibly lacks resolution

Range 10 to 10k ohm-metres 2d DC Resistivity 500m m - 0m - Range 0 to 50 milliradians 2d IP Chargeability 500m m - 0m - 2d PW MT TM-TE Resistivity Range 10 to 10k ohm-metres 500m m - 0m m - Quantec PW2dia Inversions based on algorithm by de Lugao and Wannamaker (1996) Loke 2d Inversions using Res2dInv (Loke and Barker, 1996a) Line 100S DC, IP & MT 2D & 3D Inversions 0 500m Alteration Zone Graphite Alteration Zone? -400m Unconformity Graphite? Granite-Metasediment Contact? Granite Contact? 3d DC Resistivity 3d IP Chargeability Loke 3d Inversions using Res2dInv (Loke and Barker, 1996b) Alteration Zone Graphite Alteration Zone? 500m m - 0m - 500m m - 0m - Graphite Granite Contact? Note: 2d DC suggests W-dip for M-zone Note: M-zone poorly resolved Note: M-zone alteration appears well resolved but conductor dip and contrast differs w DC Note: 3d DC indicates steeper dip Note: 3d IP resolves M-zone

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 25 A) Z=100m B) Z=250m C) Z=380m E) Z=750m D) Z=500m F) Z=1km 0 1km 10-10k ohm-m 0 1km 10-10k ohm-m 0 1km 10-10k ohm-m 0 1km 10-10k ohm-m 0 1km 10-10k ohm-m 0 1km 10-10k ohm-m PL M-zone

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

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

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

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

KEGS- EXPLORATION 07 SYMPOSIUM GEOPHYSICAL CONTRIBUTIONS TO NEW DISCOVERIES 30 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. MT data quality excellent – not hindered by ground contacts or Powerline effects – confirms all season capability. DC resistivity data quality and survey productivity greatly improved current injections (>0.5A avg), thanks to more powerful GDD Tx – suggests >2-3 season capability for DC/IP. Multi-parameter DC-IP-MT results show remarkable similarities and contrasting behaviour (i.e., DC vs MT; 2D vs 3D). DC resistivity results do not appear to be significantly hindered by powerline effects, but IP significantly more affected (acceptable). Coincident DC+MT resistivity low and IP high confirmed over graphite > additional tool for geologic mapping & discrimination. 3-D inversions simplify, improve understanding of responses.

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