The etched landsurfaces of southwestern Australia

Regolith geology of the Yilgarn Craton, Western Australia: Implications for exploration

“…Woodall (1993) and Smith (1996) noted that since 1980 much of the research relating to regolith has been driven by mineral exploration. Some studies have emphasised the weathering and mineralogy of profiles (Grubb 1966, 1971; Gilkes et al 1973, 1986; Sadleir & Gilkes 1976; Smith 1977; Davy 1979; Gilkes & Suddhiprakarn 1979; Butt 1981; Butt & Nickel 1981; Elias et al 1981; Thornber 1982; Anand & Gilkes 1984a, b, c, 1987a; Anand et al 1985; Davy & El‐Ansary 1986; Ball & Gilkes 1987; McCrea et al 1990; Lawrance 1991, 1996; Singh & Gilkes 1991; Monti & Fazakerley 1996); others have placed the regolith in a wider context (Teakle 1938; Mabbutt 1961; Bettenay 1962; Mabbutt et al 1963; Bettenay & Hingston 1964; Prider 1966; Mulcahy 1967; Bettenay & Mulcahy 1972; Finkl & Churchward 1973; Playford et al 1975; Churchward 1977; Finkl & Fairbridge 1979; Butt 1981; Glassford 1987; Brimhall et al 1988; Ollier et al 1988; Wyrwoll & Glover 1988; Chan et al 1992; Anand & Smith 1993; Kern & Commander 1993; Clarke 1994a, b; Pringle 1994; Glassford & Semeniuk 1995; Anand 1997, 2000; Jones & Lidbury 1998; Krcmarov et al 2000; Wildman & Compston 2000). Many have focused on the distribution and genesis of soils in the southern part of the Yilgarn Craton (Mulcahy 1960, 1967, 1973; Bettenay 1962; Bettenay & Hingston 1964; Finkl & Churchward 1973); others concentrated on specific materials such as Wiluna Hardpan (Teakle 1936; Bettenay & Churchward 1974), silcretes (Butt 1985), calcretes (Sanders 1974; Butt et al 1977; Carlisle 1978; Mann & Horwitz 1979; Anand et...…”

“…The etchplain concept (Wayland 1933) emphasises the formation of a deeply weathered mantle and its subsequent differential stripping. It was used by Thomas (1965) to classify weathered terrain in Africa and was applied to the southwestern region of Western Australia by Finkl and Churchward (1973). At the heart of this concept is the presumption that a continuous weathering profile covered the entire area now classed as etchplain.…”

Sandur, sandr

“…A moderate degree of stripping exposes the mottled zone, imparting a reddish-brown color to the contemporary soilscape. More extensive erosion that strips away the upper parts of the laterite profile typically exposes pallid zone materials (Finkl and Churchward, 1973;Smith, 1977;Finkl, 1979;Cornelius et al, 2001). These strongly eroded landscapes are characterized by light-colored soils derived from the pale white to gray-colored kaolinitic clays of the lower laterite profile.…”

“…Epeirocratic-rhexistatic phases on the Yilgarn Block (West Australian craton) have, for example, resulted in the stripping of regolith materials form the craton surface to produce a series of etchplains that represent degrees of soil removal (Finkl and Churchward, 1973;Finkl, 1979). The least amount of stripping is associated with incipient etchplains, which occur on the seaward-most margins of the craton, along the North-South trending Indian Ocean coastal boundary and along the East-West trending Southern Ocean coastal fringe.…”

Variety, age and origin of zircons in the mid‐Cenozoic Westonia Formation, southwestern Yilgarn Craton, Western Australia

“…A complex regolith composed principally of in situ weathered Precambrian bedrock locally overlain by variably weathered Phanerozoic detrital sediments dominates the surficial geology of the southwestern Yilgarn Craton (Finkl & Churchward 1973; Sadlier & Gilkes 1976; Finkl & Fairbridge 1979; Anand & Paine 2002; de Broekert 2003). Owing to close similarities in texture and composition between the detrital sediments and weathered bedrock, the poor preservation of fossils and primary sedimentary structures, and the masking effect of near‐surface alteration, unconformable contacts between the two major regolith types can readily escape detection.…”