This section is based on information provided in the draft EIS.
3.1 The Region
The mine is located in the headwaters of Mount Bundey Creek, within the Mary River catchment, in a secluded location approximately 15 kilometres south of the Arnhem Highway. In this area, the main activities are pastoral, tourism and recreation, in particular recreational fishing. Mining, quarrying, horticulture and defence force activities are also carried out in the general area.
The area is sparsely populated. The closest community of any size is Humpty Doo, on the Arnhem Highway, about 60 kilometres west of the mine.
3.2 Biogeography
The area where the mine is located forms the divide between the catchments of the Adelaide River and the Mary River, although the mine is in the Mary River catchment. Topographically, the project area is characterised by low, flat-topped hills with moderate to gentle slopes. Relief in the immediate vicinity is approximately 40 metres but it ranges from 30 metres to 190 metres Australian Height Datum (AHD) in the region. The vegetation of the hills is low, open and largely deciduous. The dominant vegetation of the plateaus comprises taller and for the most part evergreen trees. Creek lines in the hills have a minimum of alluvium with the vegetation indistinguishable from the adjoining slopes. The lowermost basins and creek lines have varying degrees of silty alluvium and support a distinctive tree and grass flora.
Three plant communities with distinctive soil types have been identified:
- Eucalyptus dichromoploia-E.tintinnans Low Woodland with skeletal and gravelly yellow lithosols;
- E.miniata-E.tetrodonta Open Forest with shallow lithosols and deep red earths; and
- E.polycarpa Low Open Woodland/Grassland with alluvium.
The project area lies on the northern flank of the Pine Creek Inlier within the transgressive marine sequence dominated by folded shallow marine sediments of the Early Proterozoic South Alligator Group. In general, the Pine Creek Inlier consists of an extensive, but poorly exposed sequence of Early Proterozoic sediments of low to medium metamorphic grade, which were deposited in a shallow intra-cratonic geosyncline. Cratonic basements consists of Late Archaean granites. The sediments were intruded and overlain by late Early Proterozoic volcanism and by later platform sequences of Middle Proterozoic age.
Gold mineralisation at Rustler's Roost is related to varying forms of silification occurring within a structurally prepared environment. The gold is hosted by weakly sulphitic (pyrite-arsenopyrite) banded chert mudstone sequences with varying quantities of thin quartz veining.
The climate is tropical monsoonal with two distinct seasons, and transitional periods between the two seasons. The wet season, December to March, is characterised by high rainfalls and north to north westerly winds. The dry season, May to September, has almost no rainfall with predominantly south easterly winds. Temperatures are generally high with a daily maximum temperature range of 32-37°C and a minimum range of 18-24°C. Annual average rainfall in the area is of the order of 1200 mm.
3.3 Areas of Conservation Significance
There are a number of conservation reserves managed by the Parks and Wildlife Commission in the area. The closest is the Mary River Crossing Reserve on the Arnhem Highway about 15 km to the north east of the mine. The western boundary of Kakadu National Park is 60 km to the east.