The first find of biogenic nanosiderite in oxidized ferrous quartzite of the Lebedinsk deposit, Kursk Magnetic Anomaly

Resumo

The first data on biogenic nanosiderite originally discovered in oxidized Fe-quartzites from the Lebedinsk deposit of the Kursk Magnetic Anomaly (KMA) are reported. Two generations of siderite with radically different morphology and crystal-chemical and physical properties were identified. The biogenic origin is substantiated for the late generation (nanosized siderite particles). We suggest that the early ores were transformed as a result of the evolution of the atmosphere and biosphere in the area of the KMA in the Phanerozoic. Such significant differences in the properties of biogenic nanosiderite and early rhombohedral siderite may provide evidence for their different origins. The early generation of siderite was most likely formed during an abiogenic process.