the continuity problem - srk continuity problem ... srk accepts no responsibility for any liability...

The Continuity Problem…

CIM Conference Montreal 2017Dr. Wayne Barnett

The Interpretation!

Great geological continuity?Huge potential?

CIM Conference – Montreal 2017

The Reality

Not what it might seem...Not what it might seem...


Presentation ObjectiveThe objective of the presentation is to highlight the

importance of understanding geological continuity and to describe techniques for getting better constraint on continuity, for resource and engineering reasons.

Geological continuity is a fundamental characteristic of any geological interpretation.

The difference between actual and interpreted continuity directly impacts the risk to any decision based on the interpretation, often with huge financial implications.

Unfortunately continuity is the characteristic of a sub-surface 3-D geological model that is typically the hardest to interpret with certainty.


Structures and Mineralization Continuity

Structural geology may directly control the style and continuity of mineralization.

Intersection pattern, kinematics and fluid permeability (fault zone properties)


Blast hole gold assays

Modelling Continuity

How far?

Interpreted continuity has large impact on resource and mine stability.

Requires understanding of patterns from mapping and tectonic environment.

How well does it line up?

Segmented?


Modelling Structural Continuity

Resource GeologistGeotechnical Engineer

How did I justify this interpretation?

What are the data constraints?

Where is the model confident?


Investor

CIM Conference – Montreal 2017West Claims Mine, Ortlepp ,1997

Geological systems are complex with variable properties.

How do you communicate this pattern and continuity?

Geology is not straight lines

Resource Continuity

From CIM DEFINITION STANDARDS, 2014

…evidence is sufficient to imply but not verify geological and grade or quality continuity.

…evidence is sufficient to assume geological and grade or quality continuity between points of observation.

…evidence is sufficient to confirm geological and grade or quality continuity between points of observation.


Structural Constraints on Geotechnics

From Sullivan, 2013

Fault zone orientation and continuity can constrain the slope angle

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The Continuity Problem

How can we try constrain continuity?


(1) Identify and Describe the PatternsStructural geology is recognition and understanding of patterns…

Patterns help define the possible continuity.

Map the Patterns!!!

Pattern Recognition

213 / 27

Motion tablet


Small scale

Large scale

Realistic Patterns and ContinuityUnderstand real patterns.Look for relationships between different scale structures, as well as cross-

cutting relationships.

Not realistic

Realistic


Kim et al (2004)

Brittle Deformation Patterns Impact Continuity

What is the spacing of faults and typical displacement?

Faulting can significantly reduce local continuity of the resource, increasing capital and operational costs


< 200 kaorogenic belt

• Relative timing?• When does

mineralization occur?

Ductile Deformation Patterns Impact Continuity


2.1 Ga orogenic belt

(2) Surface Traces of ContinuityAerial photographs Aeromagnetic images Surface mapping

Orthophotographs Lidar topography lineaments


(3) Continuity Evidence from Drillholesclay

RQD % shell in Leapfrog

Structural Codes – Flt, Bx, etc

North

Fracture Frequency

Clay or alteration

BH / DH assays


Oriented?!

(4) Lithological Pattern ChangesLithological offsets and thickness changes

Interpreted fault trace along offset


(5) Form Line Interpretation Pattern Changes

19

0 500

From Geoff Owen, SRK


(6) LiDAR Data Continuity TracesSurface or pit LiDAR, photogrammetry and other remote sensing data can help trace continuity.

Mapped Faults

Fracture Pattern


Photogrammetry Continuity Traces

Faults

The full trace of a discontinuity is very rarely observed!


(7) Geostatistical


Geostatistical analysis of sampled rock properties, e.g. assays, can be used to mathematical explore continuity within a geological domain.

Variography used to define estimation search ellipse continuity

Grade Estimation

(8) Integrated Geological Interpretation

Final interpretation of pattern and continuity is built based on all evidence, integrated in 3D.


Geological Foundation

• “The single most important factor in Resource/Reserve estimation is an understanding of the geology of the deposit

• This cannot be emphasized too strongly. Without a sound geological understanding, and a sensible application of that understanding, an estimation exercise becomes merely a mathematical treatment of sample results with no practical value

• Commonly the potential errors associated with an incorrect or inappropriate geological interpretation are orders of magnitude larger than the potential errors associated with grade estimation. Changes in the fundamental understanding of the geological controls on mineralization can dramatically alter an assessment of tonnage”

(Stephenson and Vann, 2001)


Example – Red Lake

Red Lake Geology

Phoenix Project Geology, 2013 TR

Northern Miner, January 13, 2016


D1-D2 Relationships,

F2 deposit, 2013 TR

Examples – Red LakeEvolution of the Litho-structural model, Phoenix Project, 2016 TR

Gold mineralization examples, Phoenix Project, 2016 TR

“The nature of these uncharacterized faults and their timing relative to gold mineralization is not understood.”

Rubicon Phoenix 2013 Technical Report

The 2016 model benefited from and extra 94,575 m of infilled drilling and 10 km of underground development.


Conclusions

Continuity is important.

One of the best tools for understanding continuity is structural geology, which constrains possible interpretations and often brings realistic expectations back into a geological model.

Modern 3-D modelling tools and the ability to integrate multiple old and new technologies into one decision making environment also helps improve interpretation of continuity….IF founded on Sound Geological Understanding


Thank you

Wayne Barnett, PhD, PrSciNat.

[email protected]

This presentation is protected by copyright vested in SRK Consulting (Canada) Inc. Neither the entire presentation or any part therein, including any images, graphs or tables, may be reproduced or transmitted in any form or by any means whatsoever to any personwithout the written permission of the copyright holder. This presentation is for informational purposes only and is not the provision of a professional service. SRK accepts no responsibility for any liability which may arise from reliance upon the contents of this presentation.


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