Abstract

Studying with precision methods the mineral composition of bauxites in the Kursk Magnetic Anomaly (KMA) made it possible to reevaluate the conditions of their formation. Occurring among Early Proterozoic jaspilites in the Belgorod ore region, they are confined to the upper part of the Early Carboniferous lateritic weathering profile on the biotite–muscovite schists. The northern part of the region is dominated by the pseudopisolitic gibbsite ores; the southern part, by the boehmite varieties with an inherited layered structure of parent rocks. Along with aluminum hydroxides, berthierine is a rock-forming (major) mineral in these bauxites. Previously, berthierine was attributed to the subsequent transformation of bauxites. Our data suggest the existence of two berthierine generations. The first generation represents a natural intermediate mineral related to the formation of bauxites during Fe concentration in the weathered rocks. Therefore, we can substantiate a certain stage in the evolution of bauxite formation in the Earth’s history leading to the formation of Paleozoic deposits.

中文翻译：

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库尔斯克磁异常（KMA）中富含Berthierine的铝土矿

摘要

用精密的方法研究库尔斯克磁异常（KMA）中铝土矿的矿物成分，可以重新评估其形成条件。发生在别尔哥罗德州矿石区的元古代早青石中，它们被限制在黑云母-白云母片岩上的早期石炭纪红土风化剖面的上部。该地区的北部主要是假蛇绿质菱铁矿。南部，由勃姆石变种，具有继承的母岩层状结构。黄连素与氢氧化铝一样，是这些铝土矿中的一种岩石形成（主要）矿物。以前，黄连素归因于铝土矿的后续转化。我们的数据表明存在两个berthierine代。第一代代表一种天然的中间矿物，与风化岩石中的铁浓缩过程中的铝土矿形成有关。因此，我们可以证实地球历史上铝土矿形成演化的某个阶段，从而导致古生代沉积物的形成。