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Subject: search.filters.subject.Geobotanical prospecting

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    The feasibility of biogeochemical and geobotanical prospecting at Spargoville, Western Australia : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University
    (Massey University, 1972) Nielsen, Jeppe Søndergaard
    Several plant species together with their associated soils from Spargoville, Western Australia, were analysed for chromium, copper, cobalt, manganese, nickel and zinc by atonic absorption spectrophotometry. Particular reference was given to nickel and copper to evaluate the usefulness of plant analysis for biogeochemical prospecting. The nickel content in the soils gave plateaus of high values over ultrabasic rock types whereas the copper levels in the soils gave peaks over areas of mineralization at ultrabasic contacts. Consideration of the plant data showed that each species accumulated different amounts of the above elements, and that they distributed these trace elements in different ways between their leaves and twigs, or between their bark and wood. Relationships between nickel and copper concentrations in the plants and in the soils were evaluated by computing correlation coefficients; promising statistical results were checked graphically. The nickel and copper concentrations in the bark of Eucalyptus lesouefii most accurately depicted the concentrations of these metals in the soils. It was also found that the barks of Eucalyptus lesouefli, Eucalyptus longicornis and Eucalyptus torquata could be used together for prospecting purposes. In the cases where the soil-plant relationship was either very good or very poor, it seemed to make no difference whether parametric or non-parametrie correlation coefficients were used. When the relationship was intermediate between these extremes, however, the non-parametric statistic was superior. A geobotanical study was also carried out tn determine whether the distributions of the plant species was related to the geolory. Dodonaea lobulata. Pittosporum phillyraeoides and Trymaliun ledifolium were found to grow only on ultrabasic rook types, and the outer, black bark of E. lesouefii growing in mineralized ground was observed to grow to a greater height on the trunk than occurred when this species grew in non-raineralized soils. when discriminant analysis was applied to plant mapping data, the different rock types could be effectively discriminated using the relative abundances of as few as one-third of the species present. These results were markedly superior to those obtained when discriminant analysis was applied to some biogeochemical data.
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    Botanical methods for mineral exploration in Western Australia : a thesis in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Massey University
    (Massey University, 1972) Severne, Barry Charles
    The application of vegetation to mineral exploration was investigated in the semi-desert mulga zone of Western Australia. Acacia aneura (mulga) dominated the vegetation and was employed in several biogeochemical surveys to locate subsurface copper and nickel mineralisation after successful orientation surveys over outcropping areas. Copper concentrations in A. aneura leaf were adequate for locating cupriferous zones in the Murchison Region. In the Kurrajong Region, A. aneura was employed to locate nickel sulphide mineralisation in a terrain of serpentinised and lateritised ultrabasics, characterised by high and variable nickel levels. It was possible to distinguish sulphide mineralisation from lateritic areas by consideration of coincident nickel and manganese biogeochemical anomalies. A nickel-accumulating variety of the shrub, Hybanthus floribundus, was discovered in the Kurrajong Region. Other Hybanthus varieties were also found to accumulate nickel, in more southern parts of Western Australia. Plant chemistry studies indicated thst nickel was concentrated in the leaf epidermis as a small, water-soluble positively-charged complex. The value of these nickel-accumulating shrubs in locating nickeliferous areas was demonstrated. Preliminary attempts to detect this shrub, from the air, using colour infrared photography were unsuccessful, although the potential of colour film to take advantage of the anomalous yellow colour during the summer season was realised. Three tree species, Acacia coolgardiensis, A. resinomarginea, and A. burkittii, exhibited pronounced geobotanical relationships. The first two species were restricted to metabasalt and metagabbro ridges, whilst A. burkittii characterised calcareous serpentinised pyroxenites. It was found that a usable colour infrared image could not be obtained by vertical aerial photography because of the infundibular growth-form exhibited by this xerophytic vegetation. However the application of this film to photogeology was confirmed. The possibility of using selenium as a path finder for sulphide mineralisation was investigated. A suitably-rapid instrumental method for the determination of selenium and tellurium was developed and a selenium accumulating tree, Acacia oswaldii, was subsequently discovered. A known toxic shrub, Swainsona canescens, also accumulated selenium, and the potential of this selenifereus flora in locating sulphides has yet to be demonstrated. It was concluded that the research embodied in this thesis has indicated the application of botanical methods to mineral exploration in the Eremean Province of Western Australia, and has outlined promising avenues for further investigations.