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Spatial Patterns of Mineral Deposits in the Broken Hill Region

New South Wales, Australia

All images and text are Copyright © 2005 by Larry Robinson

PowerPoint 6-6

Prepared as part of:

The Spatial and Temporal Distribution of theMetal Mineralisation in Eastern Australia

and the Relationship of the Observed Patternsto Giant Ore Deposits

byLarry Robinson

A thesis submitted for the degree of

PhD

2006

New South Wales Topography1

The High Temperature Type Deposits

The Broken Hill TypePredominantly stratiform disseminations or pods of galena-sphalerite quartz gahnite lode.

The Giant Broken Hill Deposits

The three giant ore deposits beneath and immediately south of the city contained"over 200 million tonnes of high gradelead-silver-zinc ore".

Barnes (1980)2

The Minor Broken Hill Deposits

The production from the 525 minor deposits was "only a few thousand tonnes of ore"from each deposit.

Barnes (1980)2

The Giant and Minor Broken Hill Deposits

Pattern Recognition by Clustering theBroken Hill Type Deposits

The AUTOCLUST AlgorithmThe approach automatically extracts boundaries based on Voronoi modellingand Delaunay Diagrams.

Parameters are not specified by users in the automatic clustering.

All clustering operations takes place on the Delaunay Diagram where data points become vertices and edges connect pairs of points to model spatial proximity.

Estivill-Castro & Lee (2000)3

Area Clustered

Delaunay Diagram, m = 0.8, noise = 0%

Voronoi Tesselation (without deposits)

Voronoi Tesselation and Clusters

Voronoi Tesselation and Boundaries

Voronoi Tesselation and Polygonization

Polygonization

Polygonization with Giant Deposits

Polygonization with Radial Trends

The Lower Temperature Type Deposits

Thackaringa Type*Mount Robe Type*Gold Vein Type*Iron Duke Pyrite TypeEttlewood TypeSilver King TypeWaukeroo TypeVein Pyrite TypeGreat Eastern TypeVein Cu Type

*These reveal the pattern adequately.

New South Wales mineral exploration data package, 2004New South Wales Department of Mineral Resources, CD-ROM

Thackaringa Type Deposits

Narrow veins or shoots and pods in veins in fault zones of argentiferous galena bearing siderite quartz veins.

Thackaringa Type and Giant Broken Hill Type Deposits

Mount Robe Type Deposits

Narrow long tabular bodies of galena-sphalerite-chalcopyrite-(gold) bearing quartz fluorite veinswhere the veins transgress layering in host.

Mt Robe and Giant Broken Hill Type Deposits

Gold Vein Type Deposits

Pyritic or cupriferous quartz vein with gold.

Gold Vein Type and Giant Broken Hill Type Deposits

The High Temperature Giant Broken Hill Type and the Three Lower Temperature Type Deposits

Giant High Temperature and Lower Temperature Type Deposits

The following image shows the probable thermal gradient in the Broken Hill Region when the giant deposits were forming.

The Paleothermal Thermometer

The HOT ZONE is delineated by the Lower Temperature Deposits.

The HOT ZONE in the Broken Hill Region

The majority of the Broken Hill Type Deposits occur in the HOT ZONE.

The HOT ZONE and Polygonization of Broken Hill Type Deposits

The ellipticity of the HOT ZONE indicates that compressional forces, in an E-W direction, distorted the original spatial distribution of the deposits.

The HOT ZONE with compression arrows (blue)

The Complex Geology in the Broken Hill Region

A prime example of the small-scale complexity in the crust and the large-scale simplicity in the underlying mantle.

From 1969 to about 1972, the impact of the geological ideas stemming from plate tectonics was muted by the characteristic geological aversion to bold, rational solutions to geological problems: small-scale complexity commonly retards and obscures our understanding of larger-scale simplicity. (p. 237)

John F. DeweyPlate Tectonics and Geology, 1965 to Today

(Oreskes, 2001)

Thank You

The End

References

1. NewSouthWales_MineralExplorationDataPackage, 2004, New South Wales mineral exploration data package: Sydney, New South Wales Department of Mineral Resources, p. 1 CD-ROM

2. Barnes, R. G., 1980, Types of mineralization in the Broken Hill Block and their relationship to stratigraphy, in Stevens, B. P. J., ed., A Guide to the Stratigraphy and Mineralization of the Broken Hill Block, New South Wales - Record 20, Geological Survey of New South Wales, p. 33-70

3. V. Estivill-Castro and I. Lee. AUTOCLUST: Automatic Clustering via Boundary Extraction for Massive Point-data Sets. In Proceedings of the 5th International Conference onGeocomputation, 2000. to appear. Extended version is available at http://www.cs.newcastle.edu.au/Dept/techrep.html as a technical report.

4. * http://users.indigo.net.au/don/ore/executive.html

5. Oreskes, N., and Le Grand, H., 2001, Plate tectonics : an insider's history of the modern theory of the Earth, Boulder, Colo., Westview Press, xxiv, 424 p.