Geological & Geophysical Interpretation of ZTEM EM and Magnetic Survey Kemess Project, BC for AuRico Metals Inc. September, 2016 Nicole Pendrigh SUMMARY REPORT
Regional setting Located in North central British Colombia Regional geology The project area lies in the western margin Intermontane Belt of the Canadian Cordillera a succession of volcanic arcs and accretionary complexes formed by subduction of oceanic plates under the North American plate and subsequent collisional tectonics. The Intermontane Belt hosts porphyry type deposits, and includes the volcanic, sedimentary and plutonic Stikinia Terrane. The Mesozoic Toodoggone District of the Stikinia Terrane hosts Au Cu Mo porphyry deposits and Au Ag epithermal systems. Mineralization dates from approximately 200 Ma in the Kemess project area. The main directions of the structures are northwest to N S and are offset by northeast structures. Most faults are steeply dipping normal faults, strike slip and thrust faults are less common.
Project and deposit setting Deposit Geology The Toodoggone District is comprised of 4 Groups: Early Permian Asitka marine sedimentary and volcanic rocks Mid Triassic Takla basalt Late Triassic to Early Jurassic Hazelton volcanic and volcaniclastic rocks Cretaceous Sustut conglomerates and interlayered mudstones, sandstones and ash tuff Upper Triassic to Lower Jurassic mineralization associated with plutonism Black Lake calc alkaline plutons and dykes intrude the Asitka, Takla, and Hazelton Groups North Kemess and South Kemess Au Cu porphyry deposits intrude into the Takla basalt
Primary geophysical datasets ZTEM EM and Magnetics Condor undertook the assessment of the ZTEM survey in light of the known geology. This assessment involved analysis of the EM and magnetic data sets and an examination of the outcomes as grids as well as 3D products. In addition to the ZTEM data, Condor was provided with the following from AuRico: Historic airborne surveys, including a 2002 DIGHEM survey Geology map for the Kemess project area Location of deposits in the project area
Primary geophysical datasets ZTEM EM and Magnetics Condor undertook the assessment of the ZTEM survey in light of the known geology. This assessment involved analysis of the EM and magnetic data sets and an examination of the outcomes as grids as well as 3D products. In addition to the ZTEM data, Condor was provided with the following from AuRico: Historic airborne surveys, including a 2002 DIGHEM survey Geology map for the Kemess project area Location of deposits in the project area
Magnetic Results Reduced to Pole (RTP) Kemess North is associated with a strong magnetic high Kemess South is associated with a strong magnetic low (remanent magnetization?) Analytic Signal (AS)?? Sensitive to the edges of magnetic bodies High AS represent probable intrusions, and are independent of magnetization direction
Magnetic Results Tilt Angle The ratio of the vertical and horizontal derivatives (limited to ±90 degrees) and is used to define the edges of magnetic sources Sensitive to the edges of magnetic bodies and magnetic lows/highs The zero angle provides a good approximation of source edges, while minima ( 67.5 to 90 degrees) are used to delineate structure and fabric The interpretive process involves the manual delineation and digitization in ArcGIS of discrete magnetic domains, followed by a geologicallyintuitive interpretation to define geological units and faults.
Outcome Outputs include a series of Tilt Angle polygons which can be resampled to assign value statistics according to the original data This output provides the base for a geophysical domain classification and litho structural (solid geology) interpretation
Outcome Outputs include a series of Tilt Angle polygons which can be resampled to assign value statistics according to the original data This output provides the base for a geophysical domain classification and litho structural (solid geology) interpretation
Outcome Result is best presented as a geophysical domain classification and structural interpretation map, with overlay of published geology Magnetic domains, classified by their geophysical attributes, represent main variations in magnetic character, assumed to reflect major rock units *Magnetic data reflects both shallow and deeper sources, thus interpretation commonly differs from surface geology *Problem is enhanced by cover and sub horizontal, magnetically active volcanic stratigraphy
ZTEM Results A suite of grid products are generated from the ZTEM survey and include Apparent Conductivity (AppCon), Total Derivative (DT), and Total Phase Rotation (TPR) at 30/45/90/180/360/720 Hz As is often the case, no one product or frequency captures all the features of interest. All grids were examined to produce an overall assessment of the results For this summary, the 180 HZ AppCon, DT and TPR are displayed for the analysis
EM Interpretation High conductivities generally correspond to contacts and structure, as well as mineralized dioritic deposits, and possible correlation with Hazelton Gp andesites High conductive ridge at Kemess North corresponds to a magnetic high domain, and a magnetic low domain at Kemess South Low conductivities (resistive) may represent non mineralized, non sulphidic diorites: The Sovereign and Duncan Plutons generally correlate to EM low areas. Published geology lends no insight to the large EM low west of Kemess South (also a magnetic low).
3D Analysis A 3D perspective view of EM 3D model Sections extracted from 3D voxel showing modelled conductivity Isosurface (green) = 0.0001 S/m
3D Analysis D A 3D modeled conductivity Sections A (W E) and D (S N) A *Horizontal grid is 500 m depth slice, with GeoInterpreted faults D
Data Integration Other Data sets Radiometrics from 2002 DIGHEM High K corresponds to: Duncan Hazelton Gp Sovereign Black Lake Intrusives Maple Leaf Potential Alteration Low K correlates with marine shales and basaltic rocks
Data Integration Other Data sets Radiometrics from 2002 DIGHEM 1992 IP Survey Chargeability Coherent Sulphide System 1992 IP survey Chargeability
Data Integration
Summary Conductive linears interpreted to be contacts or faults. These generally correlate well with magnetic structure. Low conductivities (resistive) may represent nonmineralized, non sulphidic diorites. High conductive ridge at Kemess North corresponds to a RTP magnetic high domain, and a magnetic low domain at Kemess South. The Analytic Signal of the RTP shows highs over both deposits, indicating the intrusive response at Kemess South is masked by remanence. Two other possible remanence masked intrusions are recognized between Kemess South and Kemess North. High K values, generally indicating potassic alteration, correlate with dioritic intrusives. A high chargeability zone, indicating a sulphide system, is correlateable to the K. A linear feature apparent in the K data, is also prominent in the ZTEM data, and correlates to a delineated contact in the published geology.