Nature and origins of granitic regolith in bauxite mine floors in the Darling Range, Western Australia

Kew, Geoffrey; Gilkes, Robert; Mathison, Charter

doi:10.1080/08120090801888602

Cited by 4 publications

(1 citation statement)

References 17 publications

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“…The different zones reflect different parent materials and/or differences in the extent and type of alteration (Eggleton 2001). An interpretation of how the highly diverse granitic rocks influence regolith genesis and properties at scales of metres to tens of metres has been published by Kew et al (2007). The use of the term 'zone' has been adopted in this paper to describe those mine floor materials which are natural and not constructed soil horizons.…”

Section: Bauxite Mine Floor Regolithmentioning

confidence: 99%

Properties of regolith beneath lateritic bauxite in the Darling Range of south Western Australia

Kew

Gilkes

2007

Soil Res.

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A morphological key has been developed for regolith that is exposed during mining of lateritic bauxite in the Darling Range of south Western Australia. The key distinguishes materials with different mineralogical and chemical properties. Iron oxide cemented (Zh) regolith has a gibbsitic matrix, quartz-rich (Zm) regolith has a gibbsite and kaolin matrix, and clay-rich (Zp) regolith has a kaolin matrix. An Si affinity element map (Si, Hf, Th) and a K affinity element group (K, Ba, Rb) are associated with granitic quartz-rich regolith and an Al/Fe element affinity group (Al, Fe, Ti, P, Ni, Co, Cu, Mn, Zn, Ga, Cr, V) is associated with clay and iron rich regolith. Doleritic regolith is generally associated with the Al/Fe affinity group. Although granite and granitic regolith exhibit similar element affinity groups, the abundance of elements within each is highly variable, which reflects the diversity in composition of granite within the region. The degree of euhedral character of clay-size platy crystals (kaolinite/gibbsite) does not differ for materials distinguished by the key, as both quartz-rich (Zm) and clay-rich (Zp) regolith and both granitic and doleritic saprolite contain subhedral kaolin crystals. The crystal size of platy kaolin (approximately 0.5 µm) is similar for different mine pits and for different regolith materials (Zm and Zp) within mine pits. There is a difference in halloysite tube length (0.52-1.18 µm) between mine pits, which may be related to the presence of weathered mica or to the alteration of halloysite in gibbsite-rich regolith. The internal and external diameters of halloysite tubes (about 0.11 and 0.24 µm) are similar for different mine pits and different regolith types within mine pits. The resin used during thin section preparation contains chlorine, so that determination of chlorine by EMPA provides a measure of the porosity of regolith material. A systematic negative relationship exists between chlorine concentration and total oxide weight % of porous regolith matrix determined by EMPA; both measurements provide an indication of the porosity of the clay matrix in regolith.

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Section: Bauxite Mine Floor Regolithmentioning

confidence: 99%

Properties of regolith beneath lateritic bauxite in the Darling Range of south Western Australia

Kew

Gilkes

2007

Soil Res.

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Soils of the humid and sub-humid tropics

Stahr

Herrmann

2023

Encyclopedia of Soils in the Environment

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Relationships between fabric, water retention, and strength of hard subsoils in the south of Western Australia

Kew

Gilkes

Evans³

2010

Soil Res.

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Crop yield in the sandy soils of the Western Australian wheatbelt is influenced strongly by the plant-available water (PAW) and strength of subsoils. The fabric of hard subsoils of fluvial and aeolian origin has been compared with that of in situ saprolite materials that also occur as subsoils in Western Australia. A fabric classification was developed and relationships between, fabric, water retention, and strength were examined. The clay matrix of hard subsoils is denser and is less porous than in saprolite. Hard subsoils contain rounded quartz grains and transported, rounded aggregates of clay (spherites), while saprolite contains angular quartz grains in a more porous isotropic kaolin clay matrix developed by in situ weathering. At all matric potentials there were large differences in water retention between hard subsoils and saprolite. The dry and wet strengths of subsoils are lower than for saprolite but the strength of both materials is similarly affected by changes in water content and matric potential. A variety of factors including the size, shape, degree of sorting of quartz grains, distribution of dense clay matrix, and cementing by iron oxides or amorphous silica affect the strength of subsoils. The fabric classification is predictive of water retention and strength.

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Nature and origins of granitic regolith in bauxite mine floors in the Darling Range, Western Australia

Cited by 4 publications

References 17 publications

Properties of regolith beneath lateritic bauxite in the Darling Range of south Western Australia

Properties of regolith beneath lateritic bauxite in the Darling Range of south Western Australia

Soils of the humid and sub-humid tropics

Relationships between fabric, water retention, and strength of hard subsoils in the south of Western Australia

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