Transcript Box - Online Geospatial Education Program Office

Multispectral and Surface Sampling
approach to
Gold Exploration in Marble Bar,
Australia
Kevin D. Box
Advisor: Dr. Jay Parish
GEOG 596A
Second Spring Semester
General Outline
• Project Objective
• Background
–
–
–
–
Criteria for economic success
Deposit Type
Deposit Deposition
Area of interest
• Methodology
– Data
– Work flow
– Ratios
• Potential Exploration Targets
• Moving Forward
Project Objective
• Utilize remote sensing techniques to identify potential
gold bearing conglomerates within the Marble Bar Basin.
• Actively explore targets, identified from remote sensing,
using field work and surface sampling to validate success
and failures of remote sensing in exploration.
Background
• Economic Gold Deposits
– Grade
• Must be high enough to warrant mining
– Tons
• Must have enough gold to warrant mining
– Geometry
• Deposit must be large enough to warrant cost of mill and
extraction methods
– Depth
• With excessive depth comes excessive waste and cost
The four combined factors create a formula that is the primary criteria for
whether a deposit can economically be mined at a profit. Many deposits
do not meet these criteria to be economically profitable.
Gold Deposits
• Disseminated
– Very fine grained gold dispersed through the rocks. Large
deposits and usually low grade but still economically feasible.
• Carlin, Nevada
• Cripple Creek, Colorado
• Homestake, South Dakota
• Vein (Lode)
– High grade concentration as a result of hydrothermal solutions
being forced through faults or fractures. Very high
concentrations within a tight space.
• Sleeper, Nevada
• Mother Lode, California
Gold Deposits
• Placer
– Gold deposition as a result of weathering and being moved by
water. These are usually formed with alluvial and beach
systems.
• California Gold Rush
• Klondike, Canada
• Nome, Alaska
• Paleoplacer
– “Old” placers. Old placers that have been fossilized into rock.
Deposited in a sheet and can be kilometers long. Gold can be
disseminated and crystalline.
• Witwatersrand, South Africa
– 1.5 billion ounces
– Over 4km deep
Paleoplacer Gold Origin
• Multiple Theories –
– Placer Model
• Occurred during orogenic formation
– Hydrothermal Model
• Sediments were deposited and fluids were hydrothermally
pumped into the sediment seams then compressed to
reform as rock
– Microbial Model
• BUGS!
– Gold concentrations in seawater during the time of deposition
could have ranged from 4 – 40 ppb (compared to today of 4ppt)
– Microbes play a role in exhaling gold from seawater and creating
pyrite in the process. Also could explain the formation of the high
grade carbon leaders in the Witwatersrand deposit
Basin Sediment Deposition
The three theories agree that paleoplacers are sediment deposited.
Trapped Sediments
Sediments Reworked in Streams
Shoreline Sediment Deposition
Sediment deposition
Gold Bearing Conglomerate(s)
Volcanic
Cover
Sediment Package
Basement Rocks
Examples of Gold Bearing Quartz Pebble Conglomerate from diamond drilling
at Nullagine, WA
Why Australia?
Pilbara Exploration
•
Marble Bar Basin
•
•
Nullagine Basin
Multiple basins identified in remote
regions of Western Australia that
contain potential economic
sediment hosted paleoplacer gold
systems similar to Witwatersrand,
South Africa
Nullagine – resource of 421k oz.
inferred gold defined in 2012 from
initial drilling by Novo Resources
Corp. in gold bearing conglomerates
Novo Resources Corp. exploration
identified a gold bearing
conglomerate on the opposite side
of the basin over 1km long with
grades in excess of 10 gpt up to 50
gpt at surface.
Marble Bar Basin
Question: Does the Marble Bar Basin
hold the same potential as seen at
Nullagine in 2012?
65 km
50 km
Historical
Mining
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
Over 175,000hectares (436,000 acres) of
land to explore.
• Historical mines (alluvial and hard
rock) in in the late 1930’s and early
1940’s on the south east flank of basin
— Tassie Queen
— Just in Time
— Comet
• Sporadic ground work within interior
and flanks shows that favorable
conditions exist from stream sediment
samples in areas of easy access.
Marble Bar Basin
Complications
50 km
•
•
65 km
•
Historical
Mining
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
•
Over 175,000hectares (436,000 acres)
of land to explore.
Much of the land is only accessible via
helicopter, ATV or foot resulting in
inadequate modern exploration.
Sporadic ground work has been
limited to easy access areas. Very
little is known about the vast majority
of the basin.
Work in this region is expensive for
lodging, food, and salaries
Marble Bar Geology
• Area covered in volcanic
basalt with sediment
lenses that have the
potential to host gold
• Marble Bar Basin is part
of the Fortescue Group
consisting primarily of
Archean rocks with little
overlying Tertiary rocks
Volcanic
Cover
Sediment Package
Basement Rocks
1:100k geology map from GSWA (Geological Survey of Western Australia)
Marble Bar Geology
Characteristics of the target conglomerates
• Quartz pebbles and boulders
• Matrix is a mixture of silica with clays such as sericite, illite, and
smectite
— Note: matrix mixture includes kaolinite. However, kaolinite is a common clay remobilized from
weathering elements such as wind and water
• Low mafic content
• Low epidote, chlorite, and amphibole
• Low carbonates
Remote Sensing
Why choose remote sensing?
• Proven successful in identifying certain rock types where rocks are
exposed
— Marble Bar sits in barren dry climate ideal for remote sensing
• Inexpensive when using ASTER (Advanced Spaceborne Thermal
Emission and Reflection Radiometer) multispectral data
— Covers large areas – single tile 60 km²
— Contains 14 bands that cover VNIR (Visable Near Infrared), SWIR
(Shortwave Infrared) and TIR (Thermal Infrared) spectral ranges.
— Spectral bands of SWIR and TIR are useful in identifying clays and silica
material
— Bands can be combined into ratios based on certain mineral signatures
ASTER Spectral Ratios and
Minerals
Key spectral signatures of the Marble Bar Basin
• SWIR – 6 bands (channels)
— Carbonates, Clay, and Mafic
• TIR – 5 bands (channels)
— Carbonates, Mafic, and Silica/Quartz
ASTER Spectral Ratios and
Minerals
Spectral Example – Quartz – SiO2
• Quartz Rich Rock – B14/B12
(Kalinowski, A., & Oliver, S. , 2004)
• Silica Rich Rock – B13/B10
(Kalinowski, A., & Oliver, S. , 2004)
TIR
TIR
Band 10 Band 11
TIR
Band 12
TIR
Band 13
TIR
Band 14
Issues with ASTER
• Broad paint brush complicates supervised
classification and choosing regions of interest (ROI)
— 30m pixel resolution in SWIR
— 90m pixel resolution in TIR
• Line striping or smearing of image
— Most common in TIR bands
• Mineral spectrums can overlap and cause
misidentification
— Spectral profile comparisons are complicated
• Poor imagery
— Cloud cover
— Fire within imagery
Aster Imagery Workflow
Identify
Area
of Interest
Acquire
Imagery
Layer Stack Tiles
Mosaic Tiles
Review
Ratio Results
Band Math
Unsupervised
Classification
Experiment
Phase
Create
Individual Ratios
Re-work Ratios
Analyze Results
Map Results
Plan
Exploration
Program
Software Used
ENVI – ASTER Processing
ArcGIS - Mapping
Aster Ratios – Quartz Rich Rock
Ratio = b14/b12
(Kalinowski, A., & Oliver, S. , 2004)
Highlights areas with
quartz rich rocks. This
can include sandstones,
quartz pebble
conglomerates, veins, etc.
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Aster Ratios – Silica
Ratio = B13/B10
(Kalinowski, A., & Oliver, S. , 2004)
Highlights areas with
silica rich rocks and sands.
This can include
crystalline silica found in
the matrix of sandstones,
quartz pebble
conglomerates, veins, etc.
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Aster Ratios – Sericite, Muscovite,
Illite, and Smectite
Ratio = (b5+b7)/b6
(Kalinowski, A., & Oliver, S. , 2004)
Burn Area
Highlights clays or soils
rich in sericite, muscovite,
illite, or smectite.
**Burn areas show in SWIR bands.
When analyzing you must be aware
of this.
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Aster Ratios – Mafic Rocks
Ratio = b12/b13
(Kalinowski, A., & Oliver, S. , 2004)
Highlights mafic rocks
such as basalt, dolerite,
and gabbro. These are all
extrusive or intrusive
igneous rocks.
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Aster Ratios – Epidote, Chlorite, and
Amphibole
Ratio = (b6+b9)/(b7+b8)
Highlights areas with
minerals that are
associated with igneous
rocks at Marble Bar.
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Aster Ratios – Carbonates
Ratio = B13/B14
Areas that have a high
carbonate signature.
Most likely remobilized
calcite or calcrete.
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Aster Ratios – Final Results
Band Math = (R1+R2+R3)(R4+R5+R6)
R1-Quartz Rich Rock
R2- Silica
R3 – Sericite, Muscovite,
Illite, and Smectite
R4 – Mafic Rocks
R5 – Epidote, Chlorite, and
Amphibole
R6- Carbonates
Highlights show potential Au
bearing rocks worthy of
follow ups.
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Aster Ratios – Final Results with
Historic Stream Sediment Data
• Historic stream sediment
samples collected by
multiple parties from 2005
through 2009.
– Positives
• Anomalous grades or better
confirm areas for potential
conglomerates
– Issues:
• Sampling methods unknown
• Stream sediment data not
distributed evenly
• Currently do not have elevation
data to perform adequate
stream flow analysis
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Aster Ratios – Final Results with
Stream Sediment Data and Geology
•
•
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Geology conforms closely with
results
Three distinct areas that are part
of the Hardy Sandstone unit have
different signatures.
Aster Ratios - Targets
• Areas Identified from Aster
data that show potential
conglomerates
– Numerous areas are showing
linear type features that
could be exposed
conglomerates
– Most importantly ASTER is
telling us where not to go
© Harris Corp, Earthstar Geographics LLC © 2013 Microsoft Corporation
©METI and NASA 2001
Additional Items or Work
• Acquire DEM better than 30m resolution
– Stream flow analysis to get a better understanding of the
sources for the stream sediment samples
• Continue to work with ASTER data throughout project
– Ground work will reveal better information on modifying
ASTER ratios
• Acquire aerial multispectral data for additional analysis
– Collect training sites during field work
– Better resolution allowing for detailed spectral signature work
Time Line of Project
January
Project proposal
February
Refined Project proposal
March – April
Acquired Imagery
Analyzed Data
Research Subjects
Late April - Early May
Met with team and began field planning
Class presentation
Mid May – July
Field work
ASTER changes and refinements
Mid July – August
Surface samples return
Evaluate results of remote
sensing work
Plan Drill Program
October 29-30
Present results of field work at Geological Society of America Annual Meeting, Denver Colorado
Acknowledgements
• Dr. Jay Parish
– Penn State Advisor
• Dr. Quinton Hennigh
• Novo Resources Corp.
– Funding and use of data
References
The ASTER L1B data was purchased through the online Data Pool at the Earth Remote Sensing Data Analysis Center
(ERSDAC), (https://ims.aster.ersdac.jspacesystems.or.jp/ims/html/MaiMenu/MainMenu.html).
Department of Resources, Energy, and Tourism. (2013) Aster Spectral Bands. Retrieved 29 April 2013 from ASTER Advanced Spaceborne Thermal Emission and Reflection Radiometer http://www.ga.gov.au/earth-observation/satellitesand-sensors/aster-radiometer.html
Hennigh, Dr. Quinton. (2013, April 30). Personal Interview Regarding Paleoplacer Deposits and the Witswatersrand
Deposit. (K. Box, Interviewer)
Kalinowski, A., & Oliver, S. (2004, October). ASTER Mineral Index Processing Manual. Retrieved February 26, 2013, from
Australian Government Geoscience Australia: http://www.ga.gov.au/image_cache/GA7833.pdf
Rajesh, H. M. (2004, June 28). Application of remote sensing and GIS in mineral resource mapping - An overview.
Retrieved February 26, 2013, from J-STAGE - Japan Science and Technology Information Aggregator, Electronic:
https://www.jstage.jst.go.jp/article/jmps/99/3/99_3_83/_pdf
van der Meer, F. D., van der Werff, H. M., van Ruitenbeek, F. J., Hecker, C. A., Bakker, W. H., Noomen, M. F., et al. (2011,
August 10). Multi- and Hyperspectral geologic remote sensing: A review. Retrieved March 27, 2013, from University of
OULU Dashboard: https://wiki.oulu.fi/download/attachments/26687239/van-der-Meer-et-al-2012IJAEOG.pdf?version=1&modificationDate=1352876317000
Agar, B. (n.d.). ASTER Alteration and Mineral Mapping; Las Pampas, Cajamarca, Peru. Retrieved February 26, 2013, from
ASTER Altera: http://www.bygmining.com/pdf/ASTER%20Mineral%20Mapping.pdf
Questions?