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Curnamona Province

Geobotany

Each of the regolith landforms described supports a distinctive vegetation community. Some of the more common species within each regolith landform are described here.

Within the bedrock- dominated areas, vegetation communities typically consist of an open woodland of mulga (Acacia aneura) and dead ¿QLVK Acacia tetragonophylla) over small-leaved hop bush (Dodonaea lobulata) and rock sida (Sida petrophila), with black bluebush (Maireana pyramidata) in some areas. Figure 5 'UDLQDJH GHSUHVVLRQ FRQWDLQLQJ FRDUVH VDQGV and locally derived boulders, Bimbowrie Station. (Photo 404914) the bedrock-dominated areas (SS units, Fig. 2) generally consist of coarse quartz, feldspar and lithic fragments derived from the local geology. The major alluvial channels (ACar, Fig. 2) associated with WKH QRUWKHUO\ ÀRZLQJ %LPERZULH &UHHN LQ the NW of the station, contain dominantly quartzose sediments; however, most still contain medium sand to boulder-sized lithic fragments derived from distal bedrock sources indicative of major physical dispersion along drainage lines during large rainfall events. Alluvial plain and fan sediments are generally clay rich with quartzose sands and sand-sized lithic fragments. The vegetation within colluvial landforms consists of widespread black bluebush and limestone copperburr (Scleroleana obliquicuspis), with rosewood (Alectryon oliefolius) and bladder saltbush (Atriplex vesicaria) in some areas. However, within the VKHHWÀRZ VDQGSODLQV &+SV WKH vegetation community closely resembles that of the aeolian sandplains with an open shrubland of hopbush (Dodonaea viscosa), turpentine bush (Eremophila sturtii), black bluebush and spiny saltbush (Rhagodia spinescens), with occasional bladder saltbush, and prickly wattle (Acacia victoriae). Aeolian sediments

Aeolian sediments are commonly encountered at Bimbowrie as a thin cover of silts and quartzose sands that are present throughout the landscape and as WKLFNHU VDQG VKHHWV FRPPRQO\ ÀDQNLQJ major alluvial channels. In the north and west of the station there are a number of aeolian sandplains (ISps units, Fig. 2) WKDW FRQVLVW RI VLOWV FOD\V DQG YHU\ ¿QH WR coarse-grained, sub-rounded to rounded quartzose sands mainly derived from local alluvial channels.

Vegetation communities within the alluvial landforms include an open woodland of river red gums (Eucalyptus camaldulensis) along drainage depressions (Aed units, Fig. 2) within bedrock highs (SS units, Fig. 2) and most alluvial channels (ACar units, Fig. 2). Within alluvial plains and fans, and some channels, an open shrubland of prickly wattle, black bluebush, small-leaved bluebush (Maireana brevifolia) and EODGGHU VDOWEXVK W\SL¿HV WKH YHJHWDWLRQ

Within the aeolian sandplains, vegetation communities consist of an open shrubland of hopbush, turpentine bush, black bluebush and spiny saltbush, with occasional bladder saltbush and prickly wattle.

Table 1 highlights the plants that have been used in biogeochemical studies.

Biogeochemical sampling media

Biogeochemical exploration has been used successfully in the Northern Hemisphere since the early 1900s: especially in Russia, Canada and the United States of America. Plants have a number of potential advantages when compared to soil sampling (Hill and Hill, 2003), including:

x widespread cover across the landscape x ease of sampling

x ability to penetrate regolith or to provide an amalgamated chemical signature for an enlarged sampling area

x ability to selectively extract and concentrate some elements

x minimal site disturbance and remediation associated with sampling

x a proven selection of species for targeting a wide range of elements, mineralisation styles and regolith landform settings at regional and local scales.

0DQ\ SODQWV LGHQWL¿HG ZLWKLQ WKH broad regolith landform settings described above have been shown to be effective biogeochemical sampling media. Table 1 summarises the proven biogeochemical sampling media, and their regolith– landscape associations at Bimbowrie, and provides references for further information. Biochemical sampling is illustrated in Figure 6.

Table 1 3URYHQ ELRJHRFKHPLFDO VDPSOLQJ PHGLD DQG WKHLU UHJROLWK±ODQGVFDSH DVVRFLDWLRQV DW %LPERZULH

Plant

Regolith–landform association Weathered bedrock

Sampling scale Regional/local

Mulga (Acacia aneura)

Black bluebush

Weathered bedrock; alluvial sediments; colluvial sediments; aeolian sediments

Local

(Maireana pyramidata)

River red gums (Eucalyptus camaldulensis)

Alluvial sediments

Regional

Prickly wattle (Acacia victoriae)

Alluvial sediments; colluvial sediments; aeolian sediments

Local

Bladder saltbush (Atriplex vesicaria)

Alluvial sediments; colluvial sediments; aeolian sediments

Local

32

MESA Journal 41

April 2006

Reference

Thomas et al. (2002), Hill et al. (2003); Hill and Hill (2003)

Hill and Hill (2003)

Hill and Hill (2003), Hulme and Hill (2005)

Thomas et al. (2002), Hill et al. (2003)

Brown and Hill (2003, 2005), Hill and Hill (2003)

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