Maximising the value of NVCL HyLogger data: Understanding … · 2016-04-14 · NORTHERN TERRITORY...

NORTHERN TERRITORY GEOLOGICAL SURVEY

Maximising the value of NVCL HyLogger

data: Understanding automated

mineralogical interpretations

Belinda Smith, Mark Berman, Ralph Bottrill, Tania Dhu, Suraj Gopalakrishnan,

Georgina Gordon, David Green, Jon Huntington, Alan Mauger


Introduction

• Aims– Understanding what the HyLogging NVCL is

– New to HyLogging – understanding what it is and what it is

telling you

– HyLogger User – understanding the different levels of

processing

– Increase understanding of the methods and processes

behind the mineral outputs from TSG.


• AuScope NVCL initiative – started

in 2007

– Australia-wide drillcore

database comprising high-

resolution imagery and

mineralogical data from

spectroscopic scanning

– facilitate geoscience research

– data available to the public via

a web-based delivery system

National Virtual Core Library (NVCL)

Access Infrastructure

MaterialInfrastructure

Infrastructure

Technology Infrastructure

Human

2

1

3

4


AuScope Portalhttp://portal.auscope.org/portal/gmap.html


HyLogging basics• Produces images of the

core

• Produces reflectance

spectra (matched to

minerals)

• Improves objectivity of

core logging

• Enhances geological

understanding

• Sampling every 8mm x

8mm width for whole

length of core

• Wallara 1 (1668m / 349

core trays) = 218,125

spectra

Multiple data streams

integrated in TSG software


• Voluminous data with 100,000s spectra in a single drillhole

• Hundreds of drillholes; thousands of metres nationwide

• Automate the mineral matching with;– TSA (The Spectral Assistant). Refine with;

– Restricting minerals in TSA (uTSA)

– Creating domains in TSA (dTSA)

– Using CLS with domains

Automated Mineralogical Interpretation


Mineralogical Interpretation of HyLogger Data

The Spectral Assistant (TSA) – System MatchesAlgorithm matching to whole spectral library

TSA – User Matches (uTSA)

Manual restriction of unlikely mineralsMinerals match across whole hole

sTSA

ALL DATASETS

Domaining (dTSA)

CLS

Constrained Least

Squares

External

Validation

Creating and using scalars

(XRD, petrography, SEM)

uTSA +/- scalars

Good for basement / seds drillholes

Recommended for TIR spectra

processing (non-unique spectra) Steps are not sequential


TSA mineral matching• ‘Unmixes’ spectral response into mineral

mixes of 2 (SWIR) or 3 (TIR) using an

algorithm

• Only matches to minerals in the library

• If a mineral isn’t active in that wavelength

range, you won’t see it

• If there’s more than 2 - 3 (SWIR) or 3 -4

(TIR) minerals per spectrometer you won’t

see them

• It is NOT an assay! You get a indication of

minerals present, NOT an absolute

quantifiable modal value.

• Nonetheless valuable as nothing else is as

fast.


• Automated process which can handle (simple) mineral

mixtures very quickly

• Detailed: mineral match output for each spectrum

(8mm*18mm)

• Results returned as mineral names (rather than wavelengths)

so outputs easily understood by geoscientists

• Summary overviews can show bulk mineral changes in the

entire drilled length

Strengths of TSA Mineral Outputs


Detailed TSA outputs


TSA results…. sTSA Summary

Black shales, dolomitic quartz sandstones metamorphosed basementdolostones

epidote

talc

SYSTEM TSA

has

‘unsupervised/

unedited’

watermark.

Mathematical

fit; no geology

used.


TSA results…. uTSA Summary

quartz

calcite

calcitedolomite

chlorite

amphibole

USER (uTSA) –

has been

refined to

exclude unlikely

minerals when

spectral

matching.

BUT sediments

show epidote,

phlogopite

(can’t exclude

because they’re

in basement).

talc

gone

epidote still present

phlogopite


TSA results…. uTSA Summary DOMAINED

quartz

calcite

calcite dolomite chlorite

amphibole

Results have

been

DOMAINED; no

phlogopite,

epidote in

sediments but

is in basement. epidote gone

talc, phlogopite removed

epidote still here


TSG SOFTWARE – mineral matching (TSA)

Well-crystalline kaolinite 100%SRSS = 146

Petermann Sandstone; from LA05DD01Quartz 100%Does not see kaolinite feature Appears to be a well-sorted sandstone

TSA SWIR response of wx kaolinite only

TSA TIR response of quartz only

SWIR can’t ‘see’ quartz

CLS has quartz AND kaolinite

SWIR & TIR results

93% quartz, 6% kaolinite

black = spectrumblue = modelled spectrum

black = spectrumblue = modelled spectrum

black = spectrumgreen = modelled spectrum

SWIR TSA says..

• FeMg Chlorite

• Phengitic mica

TIR Spectra Mixing

non-uniquenessTIR TSA

Result

Slide courtesy Andy Green, OTBC Pty Ltd


• TSA can’t effectively look at as many mixtures in the TIR

(n=3). CLS can return 6 – 7 mixtures

• TSA has difficulty with non-unique spectra

• TSA concentrates on getting the best fit over the whole

spectrum and may miss small features (think kaolinite in

Petermann Sandstone)

• CLS has to use a manually selected Restricted Mineral

Set (optional in TSA)

CLS vs. TSA in the TIR


• HyLogger returns voluminous whole-of-drillhole measurements vs. individual point sampling done with hand-held devices

• HyLog FIRST, destructive sampling SECOND (when wanting to compare mineral results from two techniques)

• HyLogger weakness is quantifiable mineralogy

• Mineralogy validation ongoing; many Surveys have in-house XRD facilities

HyLogging vs. other mineralogy outputs: XRD / EDAX / Petrography


• Relatively semi-quantitative– May depend on absorption co-efficient

– Linear surface measurement (not whole core)

– Does not deal well with complex mixtures

– Proportions are RELATIVE…. If a dominant mineral is inactive in that wavelength range, then it won’t be returned as a mineral match from that spectrometer

– If a mineral is < 15% of the mineral mix, it won’t be listed (default)

TSA Mineral Mix Proportions


• Core quality (look at imagery)

• Complexity of mineral

assemblage

• Degree of processing

• Incorporating scalars into the

processing workflow

• Domaining

• External validation

Factors influencing confidence levels of automated mineral modelling

The Spectral Assistant (TSA) – System Matches

Algorithm matching to whole spectral library


Manual restriction of unlikely minerals

Domaining (dTSA)

CLS

Combined Least

Squares

External

Validation



• Good for voluminous whole-of-drillhole

data

• Good for mineral matches of 2 – 3

minerals

• Good for stratigraphic

boundaries/correlations; alteration haloes

• Increased level of processing (restricted

mineral matching of algorithm using

context and common sense) gives

increased confidence in the results

• Need to learn to recognise what is likely,

what is real; what needs validation with

external techniques

HyLogger Data – ‘fit for purpose’?

The Spectral Assistant (TSA) – System Matches

Algorithm matching to whole spectral library


Manual restriction of unlikely minerals

Minerals match across whole hole

Domaining (dTSA)

CLS

Combined Least

Squares

External

Validation



• Use of scalars• Look at the imagery (core quality)• Look at the spectral fit to the algorithm• Validate using complementary

techniques (XRD, petrography, etc)• Use your geological knowledge:

– ‘am I likely to see that mineral in that geological environment?’

– is that mineral responsive in that wavelength range? (think quartz/ feldspars not showing in SWIR)

– is that mineral in the TSA library?

Validate the mineral response


• HyLogging is a valuable technique

• Automated mineralogical interpretation methods are essential to deal with the volume of data

• Understanding the methods and processes behind the mineral outputs will assist geoscientists in applying NVCL HyLogger data to their specific problems with confidence

• Next speakers can show examples of applying HyLoggerdata

Conclusions


• Andy Green (OTBC Pty Ltd) has contributed to much of this work, particularly CLS and TSA modelling work.

Acknowledgements

Validation ML48 (2012)ID TSAT Min1 TSAT Min2 TSAT Min3 TSAS Min1 TSAS Min2 XRD Comments

19301 186.28 Hedenbergite-1 57% Augite-1 43% Aspectral Clinopyroxene, ? , Pyrrhotite, Mica,

Plagioclase, Chlorite, Amphibole, Quartz

Clinopyroxene matches Na-Esseneite,

Plagioclase matches Na-Anorthite, unknown may

be sulphide

15530 158.34 Hedenbergite-1 53% Diopside-1 47% Aspectral Clinopyroxene, Pyrrhotite, Amphibole,

Plagioclase, Mica, ? , Chlorite

Clinopyroxene matches Na-Esseneite, unknown

probably Pyrite or Hematite

10915 124.62 Augite-3 59% Diopside-2 23% Grossular 1

8

%

Riebeckite 100% Clinopyroxene, Amphibole, Mica, ? ,

Chlorite


may be Garnet, Amphibole probably not

Riebeckite

39495 332.79 Albite-1 64% Quartz LH 36% Paragonite 100% K-Feldspar (35%-50%), Quartz (25%-

35%), Plagioclase (15%-25%), Mica (2%-

5%), Chlorite (2%-5%)

K-Feldspar probably Orthoclase, Plagioclase

probably Albite, Mica probably Biotite (definitely

not Paragonite)

39381 331.96 Quartz LH 58% Anorthoclase-2 42% Muscovite 100% Quartz (35%-50%), K-Feldspar (25%-

35%), Plagioclase (15%-25%), Chlorite

(5%-10%), Mica (2%-5%)


probably Albite, no Anorthoclase, Mica probably

Biotite

16893 168.37 Ankerite 81% Quartz LH 19% Siderite 100% Calcite, Clinopyroxene, Plagioclase, ? ,

Quartz


a minor constituent

16680 166.80 Siderite-1 58% Grossular-1 42% Calcite 100% Calcite, Garnet, Vesuvianite,

Clinopyroxene

Garnet probably Grossular

28913 256.01 Hedenbergite-2 56% Muscovite dbl 44% Muscovite 100% Clinopyroxene, Plagioclase, Mica,

Chlorite, Amphibole, Pyrite

Clinopyroxene probably Hedenbergite, Mica

probably Muscovite

36610 311.93 Microcline-3 69% Albite-1 31% Muscovite 51% Fe-Chlorite 46% Quartz (35%-50%), K-Feldspar (25%-


(5%-10%), Mica (<2%)


probably Albite

38343 324.56 Quartz LH 67% Anorthoclase-2 33% Muscovite 100% Quartz (35%-50%), K-Feldspar (25%-


(5%-10%), Mica (<2%)


probably Albite

38860 328.03 Quartz LH 63% Microcline-1 37% Muscovite 100% K-Feldspar (25%-35%), Quartz (25%-


(5%-10%), Mica (<2%)

K-Feldspar probably Orthoclase (definitely not

Microcline), Plagioclase probably Albite

Correct mineral Correct group Wrong group


Sample ID: PU11BRS001

Hole ID: MURD001 Index: 19470XRD response: Quartz (>80%), K-Feldspar (?microcline) (2%-5%), Dickite

(2%-5%), Mica (2%-5%), Chlorite(<2%), Jarosite13 (<2%). Mica is possibly illite.

Chlorite peaks overlap with dickite. Jarosite only detectable in fine fraction

Conclusion: XRD confirmed dickite response.Allowing an extra mixture in TSA did not identify chlorite

Validating dickite

MURD001 has a mixed dickite / muscovite TSA

response. The dickite response is quite strong

(approximately 70% dickite; 30% muscovite here;

SRSS is around 75) but is this really dickite?

Checked with XRD.

Which wavelength region is best?


Previous presentation at 2010 AESC (Huntington et al)

– Palygorskite (Lighthouse Gully Qld)

found to be zeolite (EDAX and XRD)

which was not then in TSA library

Since 2010, ongoing XRD validation carried out by Surveys to add confidence in HyLogger results

Mineralogical Validation of the NVCL via

external techniques

Sample HyLogger mineralogy XRD mineralogy

C110564 FeChlorite (60%), Kaolinite PX (40%) Muscovite (65%), Chlorite (35%)

C110565 Muscovite (80%), Kaolinite PX (20%) Muscovite (65%), Kaolinite (30%), Chlorite (5%), Goethite

C110566A FeMgChlorite (80%), Muscovite (20%) Chlorite (60%), Muscovite (40%)

C110566B Kaolinite PX (70%), Muscovite (30%) Halloysite (50%), Muscovite (35%), Chlorite (15%)

C110567 FeMgChlorite Chlorite (85%), Muscovite (15%)

C110568 Biotite (60%), Muscovite (40%) Muscovite/Biotite (70%), Chlorite (25%), Siderite (5%)

C110570 Biotite (60%), Muscovite (40%) Muscovite/Biotite (55%), Chlorite (40%), Siderite (5%)

C110571 Kaolinite WX (60%), NH Alunite (40%) Siderite (60%), Kaolinite (25%), Mica (5%), Chlorite (10%)

C110573 Dolomite Dolomite

C110574 Kaolinite (60%), FeMgChlorite (40%) Mica (40%), Kaolinite (40%), Chlorite (20%), Siderite, Ankerite

C110575 FeChlorite Chlorite (50%), Muscovite (50%), Calcite

C110576 Muscovite (50%), FeMgChlorite (50%) Muscovite (55%), Chlorite (40%), Calcite (5%)

C110577 Phengite (80%), Gypsum (20%) Chlorite, Mica, Rozenite, Gypsum/Melanterite

C110578 Muscovite (60%), Gypsum (40%) Muscovite (60%), Kaolinite (30%), Siderite (10%), Chlorite

C110579 Kaolinite WX Muscovite (60%), Kaolinite (30%), Siderite (10%)

C110580 Dolomite Dolomite (65%), Mica (25%), Kaolinite (10%), Siderite

C110581 Calcite Calcite (75%), Mica (20%), Chlorite (5%), Siderite, Mg-Kutnohorite

C110582 NH Alunite Mica (60%), Chlorite (40%), Siderite

C110583 Dolomite Mg-Kutnohorite

C110584 FeMgChlorite (80%), NH Alunite (20%) Chlorite (70%), Calcite (30%)

C110586 Calcite Calcite (80%), Chlorite

C110587 Dolomite (55%), Muscovite (45%) Mg-Kutnohorite (40%), Chlorite (25%), Mica (15%), Siderite (10%), Calcite (10%)

Validation RUL01 Alberton– MRT


uTSA compared with XRD – mineral proportionsuTSAS give 66% dolomite, 34% gypsum with SRSS of 74.

Enabling an extra mixing level gives:

49% dolomite, 30% gypsum, 21% talc with SRSS of 34.

uTSAT gives 65% gypsum, 35% quartz

XRD: anhydrite 65 – 80%; dolomite 15 – 25%; gypsum, quartz, talc (2-5%); chlorite <2%

Maximising the value of NVCL HyLogger data: Understanding … · 2016-04-14 · NORTHERN TERRITORY...

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Transcript of Maximising the value of NVCL HyLogger data: Understanding … · 2016-04-14 · NORTHERN TERRITORY...