| Origin of PhosphoriteNodules of Lebedinsky Iron Deposit in Kursk Magnetic Anomaly （KMA） of the Russian Platform |
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| 作者姓名： | TourbaKamaye PhillipRomanovitch |
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| 作者单位： | Faculty of Earth Resources，China University of Geosciences，Wuhan 430074，China，Department of Mineral Resources，Moscow State Geological Prospecting Academy，Moscow 17873，Russia |
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| 摘 要： | INTRODUCTION TheKurskmagneticanomaly(KMA)coversnear ly120000km2andhasalengthof600kminSE NW direction,withawidthrangingfrom150kmto250 km.TheKMAbasinislimitedbytheDoneskPaleozoic massifinthesouthandthePrecambrianAzovsk podol skupliftinthesouth westanditsnorthernborderis markedbythecrystallinemassifupliftofVaronesh.0 c s TheLebedinskycomplexdepositislocatedinthecentral partoftheRussianplatformbetweenlatitude50°00′and50° 20′north,andlongitude34°00′and39°00′east,inthefron ti…
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| 关 键 词： | 团状磷灰石 库尔斯克 磁异常 俄罗斯地台 生物化学处理 |
Origin of Phosphorite Nodules of Lebedinsky Iron Deposit in Kursk Magnetic Anomaly (KMA) of the Russian Platform |
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| TourbaKamaye PhillipRomanovitch.Origin of Phosphorite Nodules of Lebedinsky Iron Deposit in Kursk Magnetic Anomaly (KMA) of the Russian Platform[J].Journal of China University of Geosciences,2005,16(2):170-177,182. |
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| Authors: | Tourba KAMAYE Phillip Romanovitch |
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| Abstract: | Phosphorite has become increasingly important as the raw material for phosphatic fertilizer. Phosphorite nodules are widespread in the Kursk complex deposit (Russian platform). Genesis of these nodules has long been a matter of debate, and this has hampered understanding of the mechanism and controls in the formation of the nodules. In this paper, we report the petrographical, mineralogical, and geochemical data of the Lebedinsky phosphorite nodules. Petrographic study reveals complex phosphatic cement resulting in the replacement of apatite minerals around quartz grains. The main mineral composition consists of quartz, phosphate minerals (apatite, francolite mainly), feldspar, iron hydroxides and carbonate minerals. These results, when combined with available data, are used to address the origin of the phosphorite nodules. The nodules are characterized by the universal presence of biogenic and chemical signatures which is phosphorus crown around crystal grains. The structure of the nodules is massive. Their texture is depicted by basaltic cement and concretion, which consists mainly of apatite and its varieties, with general formula: Ca10 (PO4, CO3) 6(F,OH,Cl). Variation of mineralogy appears dependent on geological setting. Microscopic observations of biogenic fossils in Lebedinsky phosphorite favor a chemical and biogenic origin of phosphorites. Weathering has been suggested to be capable of liberating as much as 20 %-35 % P2O5 from sedimentary rocks. Previous investigations demonstrate that weathering of the Proterozoic substratum was the main cause in the formation of Fe, Mo, Mn, Pb, Zn, and P in the Russian platform. We therefore suggest that both weathering and biochemical processes have been positive in the formation of the Lebedinsky phosporite nodules. However, whether continental weathering or oceanic bio-chemical processes are more relevant in the phosphorite accumulation remains undetermined. |
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| Keywords: | nodular phosphorite Kursk magnetic anomaly Russian platform weathering bio-chemical process |
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