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9.7 Mining and the Australian Environment: 1. Where to search for ore
| Syllabus reference (October 2002 version) | ||
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| 1. The relationship between minerals and geological formations indicates where to search for ore | Students learn to:
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Student: |
Extract from Earth and Environmental Science Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW.
[Edit 28 July 09]
Background: Australia’s mineral resources are an important part of our economy but there are increasing concerns about the impact of mining on the environment in the long-term.
identify the main geological features of two Australian mineral provinces including:
- a base/precious metal- producing locality in an island arc terrane, and
- one selected from an iron ore- producing locality in an ancient continental area or an area of sedimentary ore formation
A base/precious metal-producing locality in an island arc terrane.
- When one plate subducts under another at a plate margin,
magmatic heat concentrates massive sulfide deposits of metals such as copper,
iron, zinc and silver, in the ocean crust. These are called hydrothermal deposits
and they form from hot circulating water-rich fluids. Copper ore (chalcopyrite+pyrrhotite)
from Cobar was most likely deposited in this way.
- Volcanic or extrusive deposits are also associated
with volcanic processes but are only found within the volcanic rocks themselves.
Important deposits of gold, mercury, antimony, copper and base metals are
of this type. These have formed on the ocean floor by circulating hydrothermal
fluids emanating from a volcanic vent which leach metals from the surrounding
volcanic rocks. They are currently forming on the sea floor and these are
commonly referred to as black smokers.
For
more information on minerals formed under the ocean 
Nova, Science in the News, Looking for clues to our mineral wealth, Australian Academy of Science, 1998
Another web site that may be useful Department of Primary Industry, Minerals and Petroleum
One selected from an iron ore- producing locality in an ancient continental area or an area of sedimentary ore formation
- Iron ore producing localities are found in ancient
continental areas. Most iron ore is produced from Precambrian sedimentary
deposits known as Banded Iron Formations.
A link for banded Iron Formations is Hydrothermal origin for the 2 billion year old Mount Tom Price giant iron ore deposit, Hamersley Province, Western Australia
by M. E. Barley, A. L. Pickard, S. G. Hagemann and S. L. Folkert in the Mineralium Deposita journal, November 1999
- The rocks of the Hammersley Basin outcrop over 127
000 square kilometres.
- There are three thick Banded Iron Formation units. These contain high grade ore bodies such as Mount Tom Price.
solve problems, identify data sources, gather and analyse information from secondary sources to identify the geological settings and main features of the chosen mineral provinces
- Before you can identify data sources
you need to solve the problem of which example of a base/precious
metal- producing locality in an island arc terrane you will use and which
iron ore-producing locality in an ancient continental area or an area of
sedimentary ore formation. You may decide to use the hydrothermal sulphide
ore and the Hamersley Basin iron ore outcrop or you may decide to research
different examples.
- A good data source is the NSW Department
of Agriculture, Mineral Resources. Look on their website or if you have
no success there phone them and ask to speak to their Education Officer.
Alternately you could go directly to the area, eg use a search engine and
put in words such as Hamersley, Iron ore, geology.
- Gather the information you have obtained
from the various sources including scientific journals and discard any information
that is of no use to you. You may find information on satellite images,
existing geological maps and aerial photographs of some help. Exploration
records may also be useful.
- Analyse the information you have gathered to clearly state the geological settings and main features of each of the provinces.
discuss models of mineral genesis, related to sedimentary and tectonic processes, responsible for the mineralisation in the two mineral provinces selected above.
- Jets of hot water (called plumes) on the sea floor
contain fine copper, iron and zinc sulfides.
- Ore deposits which form from these plumes are called
stratiform sulfide deposits.
- It has been found that these deposits date from
over 3000 million years ago to the present.
- These ore bodies present as lenses, ranging from
a few metres in length to over 6 kilometres and in thickness from less than
a metre to hundreds of metres.
- Leaching out of the silicates during the Tertiary has enriched some of the ore bodies in the basin.
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