Vegetation studies in the eastern goldfields of Western Australia with particular reference to their role in geological reconnaissance and mineral exploration

Abstract

Within the Eastern Goldfields vegetation studies have revealed that distinct associations characterise the different geological units. The relationship may be constant within a given field area but species differences may occur on similar rock types in different areas of the region. The physical and chemical environments are both influential in the establishment of geobotanical relationships; a vegetation association developed over an outcropping rock unit may vary from that growing on the similar unit when soil covered. Similarly, any marked changes occurring in the chemistry of the soil over differing rock types may be revealed by modifications in the plant assemblage. Thus, an increase in the soil metal content over the normal background content may affect the vegetation supported. Soil geochemical anomalies over areas of mineralisation of nickel, copper and arsenic (gold) are not always characterised by recognisable geobotanical relations: where possible relationships are observable, as over part of the Jimberlana Dyke at Norseman, and over a limited area at Kambalda, further work is necessary in similar localities of the region to substantiate them. Biogeochemical analyses may usefully indicate areas where the concentration of metals in the soils becomes anomalous, thus indicating the location of potential mineralisation. The application of the bio-geochemical method may be limited by the non-availability of elements for plant absorption.