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Channel iron deposits (CID) are iron-rich fluvial sedimentary deposits of possible Miocene age occupying meandering palaeochannels in the Early to Mid-Cenozoic Hamerlsey palaeosurface of Western Australia. Examples are also known from Kazakhstan. The deposits are anomalously high in iron for deterital material, and exclude detrital iron deposits typified by scree of hematitic banded iron formations and accumulations of currently-forming maghemite pisolite alluvials. CIDs are a major source of cheap, high grade iron ore exploited primarily in the Pilbara and Murchison regions of Western Australia. == Morphology == Channel iron deposits are typically partly eroded and currently are from between <1m to 100m thick, with preserved channel widths of between 100m and >5 km. Mineralised channels are up to 150 kilometres in length, but not all of the preserved length of the CID is of ore grade. Channel iron systems typically form within a depression on the Cenozoic ‘Hamersley Surface’, and form several pods downstream on the palaeodrainage. The channels show typical fluvial sedimentary morphology, with channel scours truncating or incising the channel iron deposits, and rare examples of graded bedding, and so on. Individual ore deposits are subsets of a larger sub-economic mineralized system, which varies laterally and along the palaeodrainage. The deposits form lensoidal accumulations with interbeds of clays, gravels and siliceous detrital materials. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Channel-iron deposits」の詳細全文を読む スポンサード リンク
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