Regolith

Shacklette H.T., Boemgen J.G. Element concentrations in soils and other surficial materials of the conterminous United States an account of the concentrations of 50 chemical elements in samples of soils and other regoliths. Washington, 1984. 

Kauranne, K., Salminen, R., Eriksson, K., (eds) 1992. Regolith exploration geochemistry in arctic and temperate terrains. Handbook of Exploration Geochemistry, 5, Elsevier. 

Fig. 1. Dissolved Mo distribution at the Baxter deposit in Western Australia has a much greater and consistent anomaly compared to dissolved Au (not shown). The results are superimposed on maximum Au contents in the regolith to show the extent of mineralisation.

Wang, X., Wen, X., Ye, R., LiuZ., Sun, B., Zhao, S., Shi, S., Wei, H. 2007. Vertical variation and dispersion of elements in arid desert regolith a case study from the Jinwozi gold deposit, northwestern China. Geochemistry Exploration, Environment, Analysis, 7, 163-171. 

Fig. 1. Distribution of whole rock geochemical data in Australia (plus signs) extracted from the OZCHEM national database as at June 2006, overlain on bedrock (pink) and regolith (green) coverages.

Lech, M. Caritat, P. de 2007. Regional geochemical study paves way for national survey - Geochemistry of near-surface regolith points to new resources. AusGeo News, 86. 

Morris, P.A. Verren, A.L. 2001. Geochemical mapping of the Byro 1 250 000 sheet. Western Australia Geological Survey, 1 250 000 Regolith Geochemistry Series Explanatory Notes, 53 p. 

Gawler Craton, located on the edge of the Great Victoria Desert (GVD). In this part of the GVD, regolith landforms are comprised of scarce hills of weathered bedrock outcrops surrounded by sand spreads, dunes and colluvial materials the hills act as windows to the otherwise covered weathered bedrock. The outcrops themselves have been silicified and, more recently, have been overprinted with calcrete. Calcrete sampling is relatively easy on the exposed outcrops and is preferentially sampled by mineral explorers due to its near-surface location (<10-20 cm depth). However, calcrete on the colluvial slopes and in the swales is not as easily located because of concealment by GVD sand and colluvium. 

Regolith samples were collected from 68 sites along a transect extending from the CTSS in the SW of the island (near napa tou Pcjpiou), across Troodos and into the CTSS and fanglomates on the NE side of Troodos (near AsuKioaia). ICP-MS trace elements concentrations were determined following two conventional (sequential) leaches on the <2mm fraction of the upper (0-25 cm) and lower (50-75 cm) parts of the profile 1M ammonium acetate in pH 5 acetic acid and 1M hydroxylamine.HCI in pH 1 HCI. 

Figure 2.1. The relationship between soil horizons, the regolith, and the underlying rock.

Stoops G, Vepraskas MJ. Guidelines for Analysis and Description of Soil and Regolith Thin Sections. Madison, WI Soil Science Society of America 2003. 

Based on the following assumptions 50 cm of saturated regolith (mantle rock), 0.5 nr g 1 surface... 

Immature soil samples have S Te values that are indistinguishable from lunar rocks, whereas submature and mature soils have 5 Fe values that are greater than those of lunar rocks, and S Te values are positively correlated with Ig/FeO values (Fig. 12). Lunar regolith samples in general tend to have heavy isotopic compositions as compared to lunar rock samples, as demonstrated by isotopic analyses of O, Si, S, Mg, K, Ca, and Cd (Epstein and Taylor 1971 Clayton et al. 1974 Russell et al. 1977 Esat and Taylor 1992 Humayun and Clayton 1995 Sands et al. 2001 Thode 1976). The origin of isotopic compositions that are enriched in the heavy isotopes has been presumed to reflect sputtering by solar wind and vaporization, where preferential loss of the lighter isotope to space occurs. In contrast to previous isotopic studies, the Fe isotope compositions measured in the Lunar Soil Characterization Consortium samples can be related to a specific phase based on the positive correlation in Ig/FeO and 5 Fe values (Fig. 12). 

Figure 12. Plot of I/FeO versus 5 Fe values of lunar regolith samples from the Lunar Soil Characterization Consortium. The sub-scripted numbers after the sample numbers are the I,/FeO values measured for the <250 pm sized fraction. All analyses are for bulk samples of the different sized fractions error bars are 2a as calculated from 2 or more complete Fe isotope analyses. Modified from Wiesli et al. (2003a).

Clayton DD (1999) Radiogenic iron. Meteor Planet Sci 34 A145-A160 Clayton RN (1993) Oxygen isotopes in meteorites. Ann Rev Earth Planet Sci 21 115-149 Clayton RN, Mayeda TK, Hurd JM (1974) Loss of oxygen, silicon, sulfur, and potassiimi from flie limar regolith. Proc Lunar Sci Conf 5 1801-1809... 

Wiesli RA, Beard BL, Taylor LA, Johnson CM (2003a) Space weathering processes on airless bodies Fe isotope fractionation in the lunar regolith. Earth Planet Sci Lett 216 457-465... 

Exploration for deeply buried gold deposits in the Bendigo region, Victoria, Australia regolith geochemistry of the Lockington area... 

Anand, R.R. 2009. Predictive geochemistry in areas of transported overburden AMIRA P778 Predictive Geochemistry in Areas of Transported Overburden. lAGS abstract. Butt, C.R.M, Robertson, I.D.M, Scott, K.M., Cornelius, M. (eds) 2005. Regolith expression of Australian ore systems. 

The results show that Au is distributed throughout the specimens and ionic Au is partly associated with a root void and possibly filaments (rootlets) within the specimen. This is the first direct evidence for ionic Au in any regolith material and is consistent with Au mobilisation within the rhizosphere. Natural ionic Au species in... 

Chan, R.A., Greene, R.S.B., Hicks, M., Le Gleuher, M., McQueen, K.G., Scott, K.M., Tate, S.E. 2004. Regolith architecture and geochemistry of the Byrock area, Girlambone region, north-western NSW. CRC LEME Open File Report 159. 71 p. 

Weathering-related rare earth element patterns in the regolith of the Cobar region, western New South Wales... 

Most of the samples for this study were collected by air-core drilling through the regolith. Samples were 1 kg splits taken with a sample spear from larger bulk... 

The very prolonged weathering of the Cobar terrain under a wide range of climatic conditions has destroyed most of the key lithogeochemical features in the resulting regolith. However, indications are variably provided by molar K/AI ratios and preserved relative enrichment in some trace elements (Sb, Tl, Ag, and patchy Pb). 

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