北海道の超鹽基性岩にともなわれる尖晶石について

概要

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Two belts of spinel-bearing ultra-mafic rocks are known along the central mountain range of Hokkaido., On account of their geological environments and lithological properties, the ultra-mafic rocks in the western belt are named "Serpentinites in the Kamuikotan Zone", and the rocks of the eastern belt are called "Peridotites in the Hidaka Zone"., The spinels associated with the serpentinites in the Kamuikotan Zone are often euhedral and show usually reddish brown in thin section., In chemical composition the spinels are always rich in chromium, and they are never beyond the limits of chromite., The mode of occurrences and chemical components of the spinels associated with the peridotites in the Hidaka Zone are quite different from those of the Kamuikotan type., In general, the Hidaka Zone spinels show anhedral and brownish or greenish tenor in thin sections., The Cr_2O_3 contents are less than 50% while in the Kamuikotan Zone the Cr_2O_3 contents of the spinels are usually in excess of 55%., In several localities in the Kamuikotan Zone, peridotite scarcely serpentinized is found ; the spinels associated with such rocks show intermediate character between the spinels of the Hidaka type and those of the Kamuikotan type., Judging from the properties of the spinels, the peridotites in the Kamuikotan Zone may not be the relict of original rocks of the serpentinites.,
日本地質学会の論文
1953-04-25