CRC LEME
Open File Report 2
ABSTRACT
Classification and atlas of regolith-landform mapping units -
exploration perspectives for the Yilgarn Craton
Anand, R.R., Churchward, H.M., Smith, R.E., Smith, K., Gozzard,
J.R., Craig, M.A. and Munday, T.J.
For geochemical exploration, regolith units form the dominant sampling
media in the initial stages of most programs. However, the regolith
evolves in a complex fashion which results in a wide variety of
regolith types at any particular site. Some of these are more appropriate
for sampling than others. It is therefore important to have an understanding
of the regolith in the region of interest in order to be able to
devise effective sampling strategies and to interpret the geochemical
data sensibly.
The classification scheme and atlas which is described in this
report has been constructed with the explorationists in mind. The
scheme and atlas should assist in the mapping of regolith-landform
associations and subsequent selection of the sampling media. It
also provides a standardized mode of description and classification
of the diverse range of regolith-landform associations on the Yilgarn
Craton. Such a standardized mode of description should allow mapping
units from one region of the Yilgarn Craton to be compared with
those from another region. These comparisons are particularly relevant
when considering geochemical thresholds for different areas and
in establishing the significance of geochemical anomalies.
The proposed classification and atlas is based on the examination
of regolith-landform settings in a series of orientation districts
across the Yilgarn Craton. The scheme is expandable, hierarchical
and mnemonic. The results presented here form the basis of continuing
work and are presented in a loose-leaf format so that findings from
other areas can be incorporated.
The classification tables contain information on regolith-landform
regimes, landforms and regolith materials. The latter are arranged
vertically in order of regolith stratigraphy. Hierarchical mnemonic
alpha-numeric codes are provided for all the designated regolith-landform
mapping units. A system of map symbols for regolith-landform mapping
units is proposed. Examples of coded maps from several orientation
districts are presented.
Representative photographs of regolith materials and their positions
in the landscape with accompanying descriptions (including geochemical
data where available) are given in the atlas. The photos and data
are arranged in the same order as those of classification tables.
The codes provide link between the classification tables, and the
photographs and their descriptions. The atlas should help exploration
geologists, geochemists and geophysicists in recognising the nature
of the regolith materials being mapped or sampled.
Future collaboration between Commonwealth Scientific and Industrial
Research Organisation (CSIRO), Australian Geological Survey Organisation
(AGSO), Geological Survey of Western Australia (GSWA), and Curtin
University will link this atlas and its incorporated concepts, with
regolith-landform mapping units for other regions of Australia.
Keywords:
Mapping methods, regolith stratigraphy, genetic regolith maps,
regolith-landform models, classification tables, atlas, Lawlers,
Mt Gibson, Mt McClure, landform, lateritic family, lag, soil, weathering
profile, substrate, transported overburden, Bottle Creek, Wombola,
lateritic nodule, lateritic pisolith, Bardoc, Lady Evelyn, Madoonga,
lateritic duricrust, ferruginous saprolite, mottled saprolite, Fe-rich
duricrust, Cawse Find, iron segregation, ferruginous granule, pisolith,
sandy clay, lateritic residuum, calcareous soil, alluvium, , Mt
Hope, mega-mottle, Black Flag, saprolite, ferruginous bedrock, glossary,
dune, erosional regime, ferruginous granule, hardened mottle. Mottled
zone, pediment, colluvium, playa, regolith unit, residual regime,
stripped slope.
Last updated: Friday, December 24, 1999 10:43 AM
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