4.
Results
4.1
Summary of the existing regional environment
4.1.1 Bioregion and subregion The study area is located within the Mount Morgan Ranges subregion of the Brigalow Belt bioregion. The Brigalow Belt bioregion covers ~36,400,000 ha of area and is named after the brigalow tree ( Acacia harpophylla ) which forms forests and woodland on clay soils within the region (Sattler & Williams, 1999). The Brigalow Belt receives ~500 - 750 mm per annum of rainfall and is a major agricultural and pastoral area (Sattler & Williams, 1999). Sattler & Williams (1999) describe the Mount Morgan Ranges as a rugged to hilly province formed on the Palaeozoic rocks of the coastal ranges from inland of Rockhampton extending southern to the Eidsvold area. The Dominant rocks are volcanics with areas of igneous rocks and small areas of folded meta-sediments. The steeper areas are dominated by narrow-leaved ironbark (E ucalyptus crebra ) woodlands with red bloodwood ( Corymbia erythrophloia) spotted gum ( C. citriodora ) and rosewood (Acacia rhodoxylon ). Silver-leaved ironbark (Eucalyptus melanophloia ) forms a woodland on erosional lower slopes and gum-topped box (E. moluccana ) forms a woodland on colluvial slopes. Forest red gum ( E. tereticornis ) and Moreton Bay ash ( C. tessellaris ) occur on alluvial soils. Bioregions and subregions are necessary for determining the REs within the project area. 4.1.1.1 Land zones Land zones represent significant differences in geology and the associated landforms, soils and physical processes and generally correspond to broad geological and geomorphological categories. They are necessarily for determine REs within the project area. Two land zones (Table 4.1) are mapped from the project area and are consistent with the surface geology mapping (see Section 4.1.2).
Table 4.1
Land zones and associated geologies occurring in the project area
Land zone
Description
10 Medium to coarse grained sedimentary rocks, with little or no deformation, forming plateaus, benches and scarps. Includes siliceous (quartzose) sandstones, conglomerates and minor interbedded volcanics, and springs associated with these rocks. Excludes overlying Cainozoic sand deposits (land zone 5). Soils are predominantly shallow Rudosols and Tenosols of low fertility, but include sandy surfaced Kandosols, Kurosols, Sodosols and Chromosols. 12 Mesozoic to Proterozoic igneous rocks, forming ranges, hills and lowlands. Acid, intermediate and basic intrusive and volcanic rocks such as granites, granodiorites, gabbros, dolerites, andesites and rhyolites, as well as minor areas of associated interbedded sediments. Excludes serpentinites (land zone 11) and younger igneous rocks (land zone 8). Soils are mainly Tenosols on steeper slopes with Chromosols and Sodosols on lower slopes and gently undulating areas. Soils are typically of low to moderate fertility. 4.1.2 Geology and Geomorphology Geology mapping covering the project area indicates that three distinct surface geologies occur.Table 4.2). Minor areas of alluvium may occur along watercourses and low-lying areas.
Table 4.2
Major surface geologies occurring in the project area
Rock unit name Precipice sandstone
Dominant rock
Lithological summary
Age
White to brown, poorly sorted, thick-bedded, cross-bedded, fine to very coarse-grained, pebbly quartzose sandstone; minor white to yellowish brown, laminated siltstone (in upper part), carbonaceous shale, lithic sublabile sandstone, granule conglomerate
Arenite
Early Jurassic
GHD | Heritage Minerals Pty Ltd | 12626510 | Heritage Minerals Mount Morgan 14 This document is in form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this document.
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