State of the Environment

2001

Marine Disturbance in Parts of the Australian Exclusive Economic Zone

Australia: State of the Environment Second Technical Paper Series (Coasts and Oceans), Series 2
David Barratt, John Garvey and Jean Chesson
Bureau of Resource Sciences, Australia
Department of the Environment and Heritage, 2001
ISBN 0 6425 4745 9

Appendix IV - Review of Exploration and Mining for Minerals

Indicators of Marine Disturbance
Offshore Minerals

Ronald G Sait
Senior Mining Engineer
Australian Geological Survey Organisation

Introduction

The Commonwealth Offshore Minerals Act 1994 regulates exploration for and mining of minerals, other than petroleum, over the continental shelf three nautical miles beyond the territorial baseline (generally the low water mark) of the States and Territories. Separate Mining Acts regulate exploration and mining in State and Territory waters.

The relevant data available for Commonwealth waters includes licence approval and renewal information, archived licence information, annual reports, seismic data and interpretations, drilling data and samples, geological interpretations and environmental data. Most of this information is unavailable to the public due to confidentiality provisions of the Act and the licence holder holds most of the information until the licence is relinquished. For State and Territory waters similar information should be available but again there would be restrictions.

The Bureau of Rural Sciences and Environment Australia agreed that the indicators for offshore minerals would include:

It was further agreed that dredging and navigation would not be covered, and that no maps would be provided.

This review summarises known offshore mineral occurrences and provides relevant information on current exploration and mining licences.

Offshore Mineral Occurrences

Most interest to date for marine sand and aggregate has been focused offshore around Sydney. Marine sand has been used for beach replenishment, for example, Hallett Cove sand was used for beach replenishment at Brighton (Adelaide).

Placer diamond exploration has been undertaken in the Joseph Bonaparte Gulf in the north west of Australia. Diamonds were discovered in Western Australian State waters in 1988 at the mouth of the Berkeley River and in 1993 at the mouth of the Ord River. No diamonds have been discovered in Commonwealth waters and to date no diamond resources have been identified. In the Gulf of Carpentaria there are two areas of potential for offshore diamonds. The first area is off the mouth of the McArthur River and the other area is the Limmen Bight. Potential for offshore diamondiferous placer deposits exist near Kangaroo Island and in the Spencer and St Vincents Gulfs in South Australia.

Minor amounts of gold are known offshore from Wynyard, Tasmania, and the potential for gold exists in Nickol Bay in Western Australia and seaward from the Mitchell River in northern Queensland.

Offshore mineral sands are known to occur off the New South Wales and Queensland coasts between The Entrance in New South Wales and Rockhampton in Queensland. Mineral sands are also known to occur off King Island, Tasmania, and there is some interest in offshore mineral sands in Western Australia, including the King Sound in the north west of the State.

Tin deposits have been identified in Ringarooma Bay, Tasmania and there is potential for tin off Cape Barren Island and King Island in Tasmania and around Bynoe Harbour in the Northern Territory.

Marine surveys by the Australian Geological Survey Organisation (AGSO) within the Australian Exclusive Economic Zone have resulted in the discovery of manganese nodules and crusts in deep waters around Australia particularly off south west Western Australia, the South Tasman Rise and Christmas Island (Indian Ocean).

Phosphorites occur off the coast of New South Wales on the continental shelf margins and seamounts.

There are a number of examples of onshore mineralisation extending seaward, including:

Exploration - Exploration Licences (as at 31 December 1998)

In Commonwealth waters a total of 64 offshore mineral exploration licence applications have been received since February 1990. Currently there are eight active licences (see Table A1). Seven of these licences are in the Joseph Bonaparte Gulf in the north west of Australia. Table A2 lists the active exploration licences in State and Territory waters.

Mining - Offshore Mining Activity

Currently there is only one offshore mining operation in State and Territory waters. Approximately 1.7 million tonnes per annum of shell sands for the manufacture of quick lime is being dredged from Success Bank, Owen Anchorage near Fremantle, Western Australia. The operation currently affects about 20 hectares of seabed a year, much of it without seagrass cover.

Dredging of calcareous sediments (coral sands) in Moreton Bay, near Brisbane, for the manufacture of cement has ceased.

There is no offshore mining activity in Commonwealth waters.

Table A1. Active offshore exploration licences in Commonwealth waters (at 31 Dec 98)
Licence Date Granted State Location Commodity Area (km²) Exploration Method
WA-1-MEL 29-Jul-90 WA 100km N of Wyndham Diamonds 358 Seismic
WA-4-MEL 22-Jun-92 WA 120km NE of Wyndham Diamonds 639 Seismic/drilling
WA-7-MEL 10-May-94 WA 140km NNW of Wyndham Diamonds 96 Seismic/drilling
NT-1-MEL 17-Jan-92 NT 170km NE of Wyndham Diamonds 1235 Seismic
NT-2-MEL 17-Jan-92 NT 140km NE of Wyndham Diamonds 1242 Seismic
NT-3-MEL 16-Apr-95 NT 300km NE of Wyndham Diamonds 1242 Seismic
NT-4-MEL 16-Apr-95 NT 200km NE of Wyndham Diamonds 778 Seismic
T-2-MEL 30-Mar-98 TAS Ringarooma Bay Tin 50 Drilling
Table A2. Active offshore exploration licences in State/Territory waters (at 31 Dec 98)
Licence Date Granted State Location Commodity Area (km²) Exploration Method
None N/A QLD     Nil None
None N/A VIC     Nil None
EL19/93 10-Apr-97 TAS Ringarooma Bay Tin 52 Drilling
EL22/95 7-Oct-96 TAS Sea Elephant Bay, King Is Mineral Sands 18 Drilling
EL18/97 17-Feb-98 TAS Sea Elephant Bay, King Is Mineral Sands 47 Drilling
EL7/97 23-Jun-97 TAS Nine Mile Beach, King Is Tin 49 Drilling
RL9802 23-Dec-98 TAS Grassy, King Island Scheelite 8 Retention Licence
EL2199 20-Sep-96 SA Port Broughton, Spencer Gulf Cu-Au 697 Survey/drilling
EL2522 16-Jun-96 SA Wallaroo, Spencer Gulf Cu-Au 198 Survey/drilling
EL3217 15-Nov-88 NSW 17km SE of Dapto Aggregate ~70 no activity
EL3218 15-Nov-88 NSW 24km ENE of Nowra Aggregate ~50 no activity
EL3219 15-Nov-88 NSW 15km ENE of Helensburgh Aggregate ~24 no activity
EL3220 15-Nov-88 NSW 17km E of Wyee Aggregate ~150 no activity
EL3221 15-Nov-88 NSW 16km SSE of Sydney Aggregate ~30 no activity
EL8166 12-May-93 NT 140km NE of Wyndham Diamonds ~50 Seismic Survey
EL8118 12-May-93 NT 140km ENE of Wyndham Diamonds ~240 Seismic Survey
EL8119 12-May-93 NT 140km ENE of Wyndham Diamonds ~220 Seismic Survey
M80/00422-437 15-Apr-96 WA 100km N of Wyndham N/A 147 Sampling/drilling
M89/00377-381 1-Nov-95 WA 80km N of Wyndham N/A 44 Seismic/drilling/sampling
E80/01541 23-Dec-93 WA 180km NW of Wyndham N/A 2 N/A
E80/01581 23-Dec-93 WA 160km N of Wyndham N/A 45 Seismic
E80/02001 1-Nov-95 WA 120km N of Wyndham N/A 22 None to date
E70/01122 15-Feb-95 WA W off Fremantle N/A 186 Sampling
E70/01136 12-Dec-95 WA Gage Roads N/A 14 None to date
E70/01141 12-Dec-95 WA Jervoise Bay N/A 13 None to date
E70/01142 12-Dec-95 WA Cockburn Sound N/A 18 None to date
E70/01197 12-Dec-95 WA S off Fremantle N/A 8 None to date
E70/01198 12-Dec-95 WA 10km SE of Fremantle N/A 8 None to date
E70/01247 24-Dec-92 WA 8km E of Fremantle N/A 36 Drilling
E70/01298 12-Dec-95 WA Carnac Island N/A 64 Drilling
E70/01300 12-Dec-95 WA 25km E of Fremantle N/A 31 Drilling
E08/00698 23-Jun-94 WA 50km SW of Dampier N/A 100 None to date