ORE SYSTEMS ANALYSIS
Revolutionary strategies for the Explorer and Mine Geologist

 

THE PRESENTER

Dr Bill Laing has consulted on over 90 ore deposits in Australia, USA, Canada, South America, North Asia, Southeast Asia, and South Africa, for over 70 client companies. Dr Laing is Managing Director of Laing Exploration Pty Ltd, and Honorary Research Fellow and founding Academic Secretary of the Economic Geology Research Unit (EGRU) at James Cook University, Australia. He has personal entries in "Who's Who in the 21st Century" and in the official Australian Academy of Science "3500 Eminent Scientists and Technologists of Australia". He is a Fellow of the Society of Economic Geologists and the Australasian Institute of Mining and Metallurgy. Dr Laing's internationally acclaimed Course, with 59 presentations worldwide, has been attended by over 900 geologists.

THE COURSE

Dr Laing has developed a set of revolutionary strategies which go to the heart of ore systems more quickly, effectively, and rigorously. These are the techniques of ore systems analysis:

· niche modelling, niche analysis, and niche exploration models
· the bonsai strategy
· metasomatic compartments
· metal profiling
· niche-based tonnes/grade analysis
· shoot analysis
· vectorisation
· stockwork analysis
· rock fertility
· audit of company culture & thinking process, and culling of counterproductive terms

Instead of conventionally pigeonholing an ore deposit into a "type", ore systems analysis internally models the ore system. Internal modelling recognises the system as a set of process sites, termed ore niches. The niches are defined on observed structural and alteration elements in the rock. The niches are defined independently of their volume in the rock. This recognises the possibility that a volumetrically minor niche, in another area may expand to mine-creating size. It lays the foundation for the key question "How can I make a mine out of niche X?". The answer involves examination of all the factors involved in the generation of niche X. This leads to the proactive identification of the appropriate structural/ metasomatic regime which will generate sufficient tonnes and/or grade to make a mine out of niche X. In this way we develop an exploration model for each ore niche, even in a greenfield terrain. The niche exploration model begins with the first outcrop or drill chips.

This is the exciting breakthrough in Dr Laing's approach: we no longer have a conventional deposit model, we have a set of niche exploration models. These accept the possibility that somewhere else, an element of the ore-forming process may create a deposit quite different from the known one(s), but still in the same ore system. "Look-alikes" in ore deposit search are now of 2 kinds: empirical, and process look-alikes. The latter may look nothing like the known deposit, but are just as accurately and confidently targeted at commencement of the exploration program. Niche exploration models reflect a more fundamental level of knowledge than conventional deposit models, which are derivative, more complex entities. Niche models are far more robust and invariant than deposit models. The latter are also used however, as "external models" which are imported for comparative "value-adding", commonly at a later stage of knowledge accumulation. A proactive, visionary exploration program uses both internal and external models, and manages both in an informed, insighful way.

Ore systems analysis emphasises that 95% of our understanding comes from 5% of the rocks. The Course teaches explorationists to constantly ask the question "Which rocks/core/outcrop do I not need to spend time on?" The Course provides the tools for deciding which are the fertile rocks, and the tools for building a suite of niche exploration models from these.

A growing number of companies are making the change to niche exploration.

ORE SYSTEMS ANALYSIS
Revolutionary strategies for the Explorer and Mine Geologist

 

INTRODUCTION: THE PROCESS FUNDAMENTALS of ore systems
Structural/fluid interaction, strain partitioning, metasomatic partitioning, the real time nature of brittle deformation, replacement and infill as the only two ore-depositing mechanisms; and their different thermodynamic budgets

THE BONSAI APPROACH
What is a bonsai; the variable fertility of rocks; the 2 fundamental data types of geology, and why it is important to know the difference; which rocks do I not need to look at? and how do I decide?

REPLACEMENT VERSUS INFILL
Why they are critical to our understanding, and what they look like in rocks

METASOMATIC COMPARTMENTALISATION
Why veins, shears and corridors change in "unexplained" ways along their length; asymmetric selvedge and its fundamental role in creating ore deposits

STOCKWORK ANALYSIS
The new holistic definition of stockwork; why 2 veins have 8 possible overprinting relationships (not 3); why veins and breccias are ultimately identical; 1D, 2D and 3D stockworks and how to use their dimensionality to identify the causative tectonic regime

NICHE ANALYSIS AND NICHE EXPLORATION
Internal modelling of ore deposits into a set of process niches; each niche has its own exploration model; dreaming your way to new ore styles; when to use - and when not to use - conventional ore deposit models; "look-alikes" in exploration, and how a look-alike can look nothing like its parent

FAULT ANALYSIS
Shortcuts to efficient fault analysis; a new way of analysing displacement from marker units; why fault analysis works particularly well in drillcore

BRECCIA ANALYSIS
Understanding breccias via their associated veins; breccia classification based on their dynamic evolution

SHOOT ANALYSIS
Is your shoot type a grade shoot, a thickness shoot, or a grade/thickness shoot? Why is it vital for your Board of Directors to know? What does the shoot type tell us about the ore-forming process?

A NEW DUCTILE/BRITTLE ORE-DEPOSIT MODEL
Can a shear zone switch movement sense along its length? the yin and yang of ductile/brittle systems and their inherent channel/trap behaviour; specially applicable to Archaean greenstone belts

STRUCTURAL GEOLOGY IN DRILLCORE
Why structural geology is easier in drillcore than in outcrop; using drillcore fertility to optimise your drillcore understanding, from core tray layout to design of drilling programs; the difference between drillcore fertility and drillhole fertility, and why you need to know; why, and how to, convince my boss that I want to drill a diamond hole as the 2nd hole in my 20 hole program

SMART MAPPING
What is the fundamental difference between smart and conventional mapping? Why do lazy people make the best mappers? Exercises in smart mapping

THINKING STRAIGHT TO OREBODIES
Do the terms we use drive our thinking, or drive out thinking? What is an exploration program? Where does our ego fit in? When does ego work for us, and when does it get in the way?

 

ORE SYSTEMS ANALYSIS

INTRODUCTION

UNIVERSAL PRINCIPLES OF ORE SYSTEMS

FUNDAMENTALS OF ORE SYSTEMS ANALYSIS
What is an ore system?
What is an ore deposit?
Ore systems analysis
Definitions
Principles of effective ore search
Mapping mineralised systems
Strategy for probing an ore system
What I want to see in my first look at an ore system
Exploration philosophies: Modelling ore deposits
Using ore deposit models
Our choice of exploration mindsets
Deposit "Look-alikes"
What is an exploration program?
Ore targeting
Ore controls
There is no such thing as structural control of an ore deposit.........
Ore controls - zoned magmatic system
Knowledge versus understanding - which do we want?
The logic of our work
Why good geologists agree about an argument
Do some terms drive out thinking?
Stop!
Interpretation in your exploration program
Understanding via smart presentation
The computer in exploration: what it can, and cannot, do
What geology does the resource estimator need?
What geology does the metallurgist need?
MAPPING STRATEGIES
Exploration mapping - master hit list
Exploration mapping - veins
Exploration mapping - faults
Exploration mapping - breccias
Exploration mapping - stockwork
Exploration mapping - selvedge
Exploration mapping - concordant mineralisation
Optimising the mapping learning curve
Getting our geometry right from the start
Approaches to outcrop
Learning curves: Mapping
Level plan analysis
Learning curves: Mine mapping
Learning curves: Drill logging
Learning curves: Diamond drill logging
Mapping with aeromagnetics
CHANNELS AND TRAPS
Channels
Evolution of plumbing from basin to metamorphic terrane
Regional channel characteristics
Traps
Plumbing diagram
Features of an ore deposit as a trap
Channels and traps: an example
Fluid:rock ratio: a dynamic entity
Geochemical study of ore deposits
The relationship between structure and chemistry in ore formation
THE BONSAI APPROACH
The bonsai principle
The bonsai approach: scale switching
Fractal behaviour: general
Fractal behaviour of faults
Using fracture patterns
Bonsai mapping: examples
ORE NICHES
Ore niches
Ore niches: example
Predicting ore niches
What is an ore niche?
Niche versus conventional ore descriptions
Niche tables
Niche analysis: pictorial log
Niches - examples
Niche exploration modelling
What is grade?
Niche assaying
Grade statistics as a guide to niche pattern
Niche versus conventional view of an orebody
Niche audit of a mining resource
Niche resource audit
Niche-based sensitivity analysis
The power of niche analysis
Spatial variability of niche grade
Ore niches: two levels
ARCHITECTURAL TEMPLATES
Templates
Architectural templates: why we need them
Architectural templates: fundamental types
The most global rock template
Getting the architectural template right
Examples
Correlation of faulted bedded units - the template
Templates: proactive and retrospective
Stope templates
Lode versus resource templates
Resource architecture
Templates: Deposit architecture - the Yilgarn
The architecture of rocks stopping
OREBODY TOPOLOGY
SHOOT ANALYSIS

Ore shoots
Making mines out of shoots
Shoot architecture as a key into the plumbing system
Shoot controls: shape versus position
Geometry of ore shoots
Relationship between lodes and shear direction in a shear zone
Recognising shoots
Grade-thickness correlation graphs
Lode profiling
Lode grade-thickness profile: examples
Bench assay contouring: example
Multiple ore controls
BIF shoot architecture
The edge of an orebody
Structure contour analysis
The rules of contouring
Structure contouring: example
Vein contouring (Conolly diagrams)
OTHER USEFUL ANALYTICAL TOOLS
Tonnes/grade analysis
PARTITIONING IN ROCKS
Fundamental domaining of rocks
Multiple stocklworks in a partitioned ore deposit

DUCTILE ORE SYSTEMS
DUCTILE STRAIN PARTITIONING

Ductile strain partitioning
Heterogeneous strain and ore plumbing
Compartmentalisation: general principles
Compartmentalisation controlled by heterogeneous strain
Compartmentalisation controlled by rock competency differences
Compartment-controlled replacement: a common scenario
Compartment-controlled ladder-veining: a common scenario
Anastomosing strain partitioning: regional examples
Strain partitioning around a fold
Strain partitioning around an ore deposit
DUCTILE STRUCTURAL GEOLOGY
Ductile structural geology
Deformation and tectonites
New cleavage from old: the sequence
THE TWO FUNDAMENTAL TYPES OF LINEATION
Folds and lineations
Relationship between folds and sequence
Vergence
Using your hands for planes and lines
Field recipe for structural analysis
FOLD BELTS AND THEIR ORE DEPOSITS
Fold (slate) belts
Fold belt ore systems: the principal types
Fold axis vs elongation lineation: relationships
Fold axis vs elongation lineation: examples in ore deposits
CONCORDANT ORE DEPOSITS
Tackling stratiform/stratabound ore deposits
What is orebody remobilisation?
The fundamental issue in remobilisation
"Folded" ore - what does it mean?
Startiform base metal deposits - determining their origin
SHEAR ZONES AND THEIR ORE DEPOSITS
Fault/shear zone systems: an overview
FSZ ore systems: their principal subtypes
Shear/fault-related ore deposits
Structural relationships between lineations in a shear zone
Why are ore shoots parallel to the shear direction in a shear zone?
High strain (shear) zones
Architecture of shear zones
Boudinage within a shear zone
Boudins: shape changes during progressive strain
Rolls versus anastomosing fabric
Dilation around indenters
Foliation-discontinuity faults
Veins in shear zones
Whay are veins parallel to cleavage?
Mapping in structural terranes


DUCTILE-BRITTLE ORE SYSTEMS
TENSION VEIN ARRAYS

TVA types in the three strain ellipsoids
TVA architecture
Sense of shear from a TVA
The information in a TVA
En echelon ore controls: shear zones without tension vein arrays
Examples: shear zones with tension vein arrays without cleavage
Examples: shear zones with tension vein arrays with/without cleavage
Examples: ore bodies controlled by tension vein arrays
Examples: ore deposits
Tension veins or shears?
Drill-testing for shoots in sigmoidal veins
The evolution of a TVA
Determining shear sense via the stereonet
Stereonet determination of shear direction from a TVA
The scale-invariance of a TVA
Permeability of a TVA
Analysing en echelon ore shoots
Shoot types - fault/TVA system
Logging and mapping a TVA
SADDLE REEF (ANTIFORM HINGE ZONE) ORE DEPOSITS
Antiform hinge zone (AHZ) deposits
Tectonic setting of AHZ deposits
Regional plumbing model
Ductile structures
Brittle stockwork - overview
Saddle deposit styles
Two phase evolution of saddle architecture
Sulphide ore niches in late deformation
Two types of saddle reef: dilational and replacive
Replacement in AHZ deposits
Shoot development
Ore potential: deposit scale
Ore potential: regional scale
Exploration for saddles

BRITTLE ORE SYSTEMS
READING BRITTLE ORE SYSTEMS

The dynamics of rock breaking and ore formation
Faults - kinematic analysis
Guidelines to brittle ore systems
ALTERATION
Alteration
All ore deposits are formed by infill or replacement
Vein dynamics: infill vs replacement
Metasomatic facies
Metasomatic facies - in veins
Metasomatic facies - in saddle veins
Replacement
Replacement: textural criteria
Managing selvedge - wood from the trees
Buck quartz - a mine of information
The replacive component in ore systems
Geometry of replacive selvedges
Aspect ratio of replacive selvedges
The architecture of replacement
Recognition of replacement architecture
Degree of replacement in an orebody
Selective replacement: manto example
Aspect ratio of manto deposits
Replacement: the Mount Isa example
Asymmetric replacement
Metasomatic compartments
Wallrock induced compartments
Recognising metasomatic compartments
Metasomatic compartments: examples
Replacement, infill and grade
The grade arithmetic of selvedge
Replacement, infill and grade: exercise
STOCKWORKS
What is a stockwork?
The architecture of stockworks
Dimensionality of stockworks
Stockwork analysis
Stockwork analysis: what to record
Stockwork analysis: example
Drill-testing stockworks: general
Drill-testing stockworks: complexities
Stockwork regimes
Stockwork regimes: examples
VEINS
Vein/vein relationships: principles
Vein/vein relationships: individual veins
Vein/vein relationships: vein sets
Vein analysis
Vein analysis logging sheet
The power of vein analysis
FAULTS: DYNAMIC ANALYSIS
Anastomosing geometry of faults
Fault geometries: bends
Fault geometries: dilational jogs
Architecture of dilational jogs type I
Architecture of dilational jogs type II
Fault geometries: dilational jogs: examples
Fault architecture: hard- and soft-linked fault systems
Fault architecture: variable displacement faults
Mineral fibre growth in faults
Faults and metasomatism: exercise
FAULTS: KINEMATIC ANALYSIS
Where do we see faults?
Kinematic interpretation of faults
Fault analysis from maps - new perspectives
Map-based regional fault analysis: how to, and how not to
Why regional fault analysis in the office commonly gives wrong answers
The relationship between fault displacement and separation
Staged fault interpretation of maps
Interpretation rules for fault displacement using marker units
Marker offset analysis: multiple markers
Mapping faults for displacement
The most effective marker units
Wrench fault analysis
Fault kinematic analysis: exercises I to IX
BRECCIAS
Breccia analysis
Breccia classification
Polygonisation preceding breccia pipes: example
From breccias to tectonic model