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– 634 . Daliran , F. 2002 : Kiruna-type iron oxide-apatite ores and apatitites of Bafq district, Iran, with an emphasis on the REE geochemistry of their

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. Wu , C. 2008 : Bayan Obo controversy: carbonatites versus iron oxide-Cu-Au-(REE-U) . – Resource Geology 58/4 , pp. 348 – 354 .

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Knowledge of the distribution and sorption characteristics of trace metals in soils is essential because of their importance both from agricultural and environmental point of view. In this paper, an overview will be provided on the relationship between the behavior and sorption properties of Cu and Pb as well as major soil characteristics, based on the results obtained by several independent research projects carried out on this field at the Institute for Geological and Geochemical Research over the last 15 years. These projects were accomplished using methods with different approaches, e.g. studying metal characteristics by total metal content, selective chemical extractions and batch sorption experiments.Our results show that both metals can be found in soils, primarily in the form of phases highly resistant to weathering. However, if they are mobilized, they are easily and strongly immobilized by soils rich in organic matter, with higher affinity for Cu than for Pb. In acid soils, on the other hand, the leaching of Cu is expected to be higher from such horizons when compared to Pb, especially when iron oxides, which immobilize Pb preferentially, are also present in these horizons. In mineral horizons the close association of Pb and iron oxides can be still expected, whereas Cu prefers to be bound both by clay minerals and iron oxides. In alkaline soils, however, precipitation of both metals as carbonates is a general feature. Our results obtained through different approaches presented in this paper were found to be effectively complementary to each other, providing a much deeper insight into soil-metal interaction than when they are used independently.

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Abstract

The Ab Ask mineral springs are located 85 km northeast of Tehran, in the southern range of the Damavand volcano. Deposits of these calcareous springs are mainly precipitated as travertine. Petrographical, mineralogical, and stable isotope studies were conducted on different types of travertine to determine their genesis and factors that govern carbonate precipitation. Based on sedimentation consequence and lithofacies these travertines are categorized as first type (fresh travertine), second type (fissure-ridge, dam, and cascade), and third type (laminated) travertines, illustrating a specific condition of formation, deposition and diagenesis. Combined XRD and microscopic investigations show that the Ab Ask travertines are is composed of about 95 % calcite and a minor amount of quartz along with iron oxide impurities. The origin and transport of springs water from which travertine was precipitated are elucidated by 13C and 18O isotopic studies of the travertines. δ18O and δ13C values of travertines increase (from −13.0 to −6.3% VPDB and from 6 to 9.8% VPDB, respectively) with increasing distance from the spring orifice. This significant increase is attributed to temperature decrease, rapid degassing of CO2, and biological activities. It seems that CO2 content of these fluids may have originated from limestone decarbonation. Based on the integrated petrographic and stable isotope study, the Ab Ask travertines can could be thermogenic in origin.

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Schwertmann, U., R.M. Taylor 1989: Iron oxides. - In: Dixon, J.B., S.B. Weed (Eds): Minerals in soil environment. 2nd edition. Soil Science Society of America Book Series no. 1, Madison, Wisconsin, pp. 379--438. Iron

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.C. Pessôa da Cruz, J.C. Casagrande 2004: Nickel adsorption by soils in relation to pH, organic matter, and iron oxides. - Scientia Agricola (Piracicaba, Braz.), 61, pp. 190–195. Casagrande J

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. R.H. Sillitoe 2003 Iron oxide-copper-gold deposits: an Andean view Mineralium Deposita 38 787 812

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216 . H.A. Nowlan 1976 Concretionary manganese-iron oxides in streams and their usefulness as a sample medium for geochemical prospectin

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Central European Geology
Authors: Ildikó Gyollai, Ákos Kereszturi, and Elias Chatzitheodoridis

whitlockite), and sulfides (pyrrhotite and pyrite) are identified as major magmatic minerals, iron oxides (goethite or hematite) as secondary alteration products; the alteration products could also have been terrestrial origin. The Zagami meteorite is observed

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