Sandstone types

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

Sandstone-type (tabular, roll front and tectonic lithologic)... 

U/ U ratios in sandstone-type uranium ores are greater than magmatic uranium ores by 1 %o, but no explanation for this difference was proposed other than a reflection of different redox conditions. 

Geochemical detection of uranium deposits in sandstone-type deposits depends on the geochemical behavior of U and pathfinder elements (Rose Wright 1980). Uranium is dispersed under oxidizing conditions but is immobile under reducing conditions. Adsorption on freshly precipitated Fe-oxides and certain types of organic matter also limits dispersion unless high concentrations of or... 

Deep-penetrating geochemical exploration for hidden sandstone-type uranium deposits in the Turpan-Hami basin, northwestern China... 

Keywords deep-penetration, geochemistry, expioration, sandstone-type, uranium deposits... 

Traditional exploration for sandstone-type uranium deposits has centered on genetic models and radiometric methods (Morse 1969 Harshman 1970 Rubin 1970). However, these methods have become prohibitive for sandstone-type uranium deposits hidden at a depth of hundreds of metres (Riese et al. 1978). Radioactivity detectors are ineffective in regions where there is a relatively thin inactive overburden (Bowie etal. 1970). 

Conventional regional soil geochemical surveys based on coarse fractions of soils (>20 mesh) to avoid windblown sand dilution for elemental contents failed to delineate uranium geochemical anomalies for blind sandstone-type uranium deposits in desert basin terrains in China. 

The authors have set out to attempt to use deep-penetrating geochemical methods, based on fine-grained fraction sampling and selective leaching in exploration for hidden sandstone-type... 

Miocene sandstone overlying Jurassic sedimentary rocks occur in the Turpan-Hami Basin. Sandstone-type uranium... 

Three geochemical provinces of U and Mo were delineated in the Turpan-Hami Basin (Fig. 3). The westernmost one contains the Shihongtan large sandstone-type uranium deposit. Sandstone-type uranium deposits are characteristic by coexisting U and Mo anomalies. The east one at Hami area is was selected for follow-up exploration and a big deposit was found by drilling program. 

Sandstone-type uranium deposits are characteristic by coexisting uranium and molybdenum anomalies. 

Fig.1. Bar graphs showing the concentrations of various elements in different size fractions of soil over the Shihongtan sandstone-type uranium deposit.

Riese, W. C., Lee, M. J, Brookins, D, G, and Della Valle, R. 1978. Application of trace element geochemistry to prospecting for sandstone-type uranium deposits. In Watterson, J.R. and Theobald, R K. (ed.). Geochemical Exploration 1978, Proceedings of the Seventh International Geochemical Exploration Symposium. The Association of Exploration Geochemists, Rexdale, Ontario, Canada, 47-64. 

Two types of deposits, where the internal S-isotope variations fit the expected scheme of bacterial reduction, but where the biogenic nature was already known from other geological observations, are the sandstone-type uranium mineralization in the Colorado Plateau (Warren 1972) and the Kupferschiefer in Central Europe (Marowsky 1969), although thermal sulfate reduction may have occurred at the base of the Kupferschiefer (Bechtel et al. 2001). 

Cowart J. B. and Osmond J. K. (1977) Uranium isotopes in groundwater their use in prospecting for sandstone-type uranium deposits. J. Geochem. Explor. 8, 365-379. 

Hostetler, P.B. and Garrels, R.M., Transportation and precipitation of uranium and vanadium at low temperatures with special reference to sandstone-type uranium deposits. Econ. Geol. 57 (1962) 137-167. 

Chatham, J. R., R. B. Wanty, and D. Langmuir. 1981. Groundwater prospecting for sandstone-type uranium deposits The merits of mineral-solution equilibria versus single element tracer methods. U.S. Dept, of Energy, Report GJO79-360-E. 197. 

CH Channel + levee Trough cross-bedded sand (St) planar laminated sand (Sp) low angle cross-bedded sand (SI) horizontally laminated sand (Sh) ripple cross-laminated sand (Sr) massive sand (Sm) massive, crudely bedded silts and muds (Fm) finely laminated to rippled silts and muds (FI) laminated silt, sand, and clay (Fsc) Tabular to lenticular 0.2-3 m thick 10 m to >2 km in lateral extent Fine to coarse, moderately sorted sand/sandstone Type 1 and type 3 (phreatic) tabular units... 

The difference between sandstone-type minerals and high-temperature minerals is considered to be significant. It is attributed probably to isotopic fractionation that occurred when uranium initially deposited at high temperatures from magmas was dissolved by water at lower temperature and reprecipitated in sandstones. The difference between non-U.S. and U.S. samples is explained in the same way, as most non-U.S. samples were of magmatic origin and most U.S. samples were of the sandstone type. 

Arkose. A rock of the sandstone type but containing 10% or more of feldspar it is formed by decomposition of granite. 

Q ROLL FRONT SUBTYPE Fig. 3 Sandstone-type uranium deposits... 

Granger H. C. al. Sandstone-type uranium deposits at Ambrosia Lake, New Mexico—an interim report. Econ. Geo/., 56, 1961, 1179-210. 

Hoeve J. et al. Athabasca basin unconformity-type uranium deposits a special class of sandstone-type deposits Reference 17, 575-94. 

Langmuir D. and Applin K. Refinement of the thermodynamic properties of uranium minerals and dissolved species, with application to the chemistry of groundwaters in sandstone-type uranium deposits. Circ. U.S. geol. Surv. 753, 1977, 57-60. 

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