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Australian East Coast Heavy Minerals - Forster-Tuncurry, Swan Bay-Tomago, Stradbroke, Moreton Island

Australia

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The east coast of Australia, from the New South Wales - Vicorian border in the south to the southern margin of the Great Barrier Reef to the north in Queensland has been a major province of heavy mineral beach placers producing large tonnages of detrital rutile, zircon, ilmenite and minor monazite.   Deposits have been commercially exploited at more than 200 localities distributed over nearly 60% of this 1500 km interval.

Mineralisation is found as strand lines and disseminated masses on beaches, in dunes and as high stand barriers of Quaternary age along the present coast line.   While individual mineral grains are terriginous, the deposits are not linked to specific source rocks in the hinterland.   They arise from wave action during the building of coastal barriers.   The heavy minerals are sourced from older consolidated sediments derived in turn through several generations of erosion and deposition from widely dispersed original igneous sources.

There are four main types of deposit as follows:

Type A - Lag Deposits which occur along erosional discontinuities in leaky embayments or between barriers of different ages where repeated storm reworking has produced beach face concentration on drift aligned sectors of coast by "littoral bypassing fractionation".
Type B - Transgressive Deposits found in back-barrier washover facies (and sometimes as condensed sections) at the rear of swash-aligned barriers in coastal embayments, produced by a process of transgressive barrier fractionation that reworked heavy minerals from shelves undergoing erosion during marine transgressions.
Type C - Regressive Deposits in prograded barriers representing episodic influxes of remobilised heavy mineral rich sand that originated elsewhere through the previously detailed fractionation mechanisms.
Type D - Aeolian Deposits which occur as relatively low grade, disseminated deposits in transgressive dunes downwind from heavy mineral rich beach sand accumulations.

The environmental conditions required include: a). low rates of new clastic sediment supply and long periods of erosion and abrasion to produce a mature heavy mineral suite, b). an energetic swell wave climate driving large sand fluxes onshore and alongshore, c). changing sea levels (particularly marine transgression) that will move heavy minerals from the shelf to the coast line.

Individual deposits may be from a few tens to hundreds of metres in width, 2 to 20 km in length, 3 to 5 m in thickness and are found in the upper part of thick barrier sand bodies around 10 m above bedrock.   They generally parallel the current coast line and range in age from 200 Ka to the present.   Ore grades from representative deposits on the NSW coast worked in the 1980s and 1990s varied from 0.4 to 1.5% HM, with the HM fraction comprising around 15% rutile, 35% zircon and 40% ilmenite at one and 37% rutile, 37% zircon, 22% ilmenite and 0.4% monazite at another site.

Production from 1941-1987 in Queensland totalled 2.183 Mt of rutile, 1.848 Mt of zircon, 1.095 Mt of ilmenite and 2830 t of monazite.   Between 1934 and 1987 New South Wales produced 4.242 Mt of rutile, 4.324 Mt of zircon, 0.499 Mt of ilmenite and 22 000 t of monazite.   The demonstrated resources on the eastern Australian coastline in 1987 were 6.3 Mt of rutile, 6.2 Mt of zircon and 13.4 Mt of ilmenite

For more detail consult the reference(s) listed below.

The most recent source geological information used to prepare this summary was dated: 2000.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.


  References & Additional Information
   Selected References:
Roy P S  1999 - Heavy mineral beach placers in southeastern Australia: their nature and genesis: in    Econ. Geol.   v94 pp 567-588
Wallis D S, Oakes G M  1990 - Heavy mineral sands in eastern Australia: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne   Mono 14, v2 pp 1599-1608


Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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