Sedimentary uranium deposits,

Rose, A.W. Wright, R.J. 1980. Geochemical exploration models for sedimentary uranium deposits geochemical exploration for uranium. Journal of Geochemical Exploration, 13, 153-179. 

An example of such a system is the sedimentary uranium deposit in Tono, Japan, studied by Nohara et al. The ground water moves through the area with a velocity of 0.001 to 1... 

Scott J. H. and Daniels J. J. Non-radiometric borehole geophysical detection of geochemical haloes surrounding sedimentary uranium deposits. Reference 5, 379-90. 

Langmuir D (1978) Uranium solution-mineral equilibria at low temperatures with applications to sedimentary ore deposits. Geochim Cosmochim Acta 42 547-569 Langmuir D, Herman JS (1980) The mobility of thorium in natural waters at low temperatures. Geochim Cosmochim Acta 44 1753-1766... 

Palaeoplacers are placer concentrations that have occurred in the geological past and which are preserved till the present by a cover of later sedimentary rocks. The Witwatersrand gold-uranium deposits (South Africa) and the uranium deposits at Blind River (Ontario, Canada) and Jacobina (Brazil) are the most important examples of palaeoplacers. 

Syn-sedimentary chemical deposits form by chemical and biochemical precipitation of valuable metal components carried in solution, concomitant with the formation of the enclosing sedimentary rock. The manner of such deposition depends on the concentration of the metal in the solvent, the solubility of the precipitating product, the solution chemistry, and the deposition environment. Iron, manganese, phosphorus, lead, zinc, sulfur and uranium are some of the elements that have formed economically valuable deposits by chemical precipitation during sedimentation. 

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. 

Most uranium deposits in sedimentary rocks are associated with geochemical provinces enriched in U and Th or with U-... 

FIolk, G.J., Kyser, T.K. Don Chipley, FIiatt, E.E., Marlatt, J. 2003. Mobile Pb-isotopes in Proterozoic sedimentary basins as guides for exploration of uranium deposits. Journal of Geochemical Exploration, 80, 297-320. 

Unconformity-type uranium deposits from the Athabasca Basin (Saskatchewan, Canada) represent the worid-richest uranium ores with the McArthur River deposit as a prime exampie. They are mainiy iocated ciose to the unconformity between a Paieo- to Meso-Proterozoic sedimentary basin, the Athabasca Basin, and an Archean to Paieoproterozoic metamorphic to piutonic basement. For severai years, a new type of uraniferous mineraiization, entireiy iocated in the basement, has been driiied in the South-Eastern part of the basin. Few data are avaiiabie for this type of deposit, iimiting the comparison of their characteristics and possibie genetic iinks with deposits iocated at the unconformity. 

Adams, S.S. Smith, R.B. 1988. Geology and recognition criteria for sandstone uranium deposits in mixed fluvial-shallow marine sedimentary sequences, South Texas. Bendix Field Engineering Corporation, Grand Junction, Colorado NURE Report GJBX-4(81), 146 p. 

Langmuir, D. "Uranium"Solution-Mineral Equilibria at Low Temperatures with Applications to Sedimentary Ore Deposits, Geochimica et Cosmochimica Acta 1982, 42, 547-569. 

Langmuir, D. Uranium solution-mineral equilibria at low temperatures with applications to sedimentary ore deposits. 

Nd. From the high isotope ratio " Nd/ " Nd and the low isotope ratio it must be concluded that chain reactions have occurred. The age of the Oklo deposits was found by Rb/ Sr analysis to be a 1.7 10 y. At that time the concentration of in natural uranium was 3%. The presence of water in the sedimentary ore deposits led to high values of the resonance escape probability p (eq. (11.1)) and to criticality of the systems ( eff > ) ... 

Sedimentary phosphate ores, such as those found in Florida and Morocco, tend to have high concentrations of uranium, whereas the opposite occurs with magmatic ores, such as apatite from Kola. Typical activity concentrations of U are 1500 Bq kg in sedimentary phosphate deposits and 70 Bq kg in apatite. U is generally found in radioactive equilibrium with its decay products. The activity concentrations of Th... 

Figure 10.7 Adsorption isotherm describing the adsorption of uranyl (UO +) species onto suspended amorphous ferric hydroxide at pH 7.23 and 25°C. The vertical line denoting saturation with respect to schoepite [U02(0H)2 H2OI has been computed from the pH and dissolved uranyl concentration. The enrichment factor, E.F., equals K,. Reprinted from Geochim. et Cosmochim. Acta, Vol. 53(6), D. Langmuir, Uranium solution-mineral equilibria at low temperatures with applications to sedimentary ore deposits, pp. 547-569,...

What geologic conditions lead to the formation of sedimentary uranium ore deposits and to their preservation for geologic times ... 

The Oklo anomaly, which was discovered as a result of isotopic assays of uranium from the Mounana mill, was first recognized as being the result of a natural fission reactor in 1972 (1,2). The Oklo uranium deposit, located in the southeast part of Gabon, occurs in one of the Francevillian series of sedimentary deposits. In the deposit the uranium concentration is... 

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