1980 Volume 30 Issue 163 Pages 289-297
More than five hundred data of nickel and cobalt contents in igneous rocks have been collected from the literatures, and the data are plotted on three diagrams of SiO2-log Ni, SiO2-log Co, and log Ni-log Co. Ni content of igneous rocks is higher in continental regions as compared with oceanic regions.The groups, continental and oceanic, can be discriminated on SiO2-log Ni and log Ni-log Co plots. The boundary between them passes through the points; SiO2 40%, Ni 900 ppm, and SiO2 70%, Ni 9 ppm on SiO2-log Ni diagram, or it has ratio of Co/Ni=0.16. Some data from the continental region are plotted in the area of the oceanic group. There is indication that their actual formative environment may be oceanic rather than continental. The data of the submarine volcanics associated with stratabound ore deposits in Japan, such as Kieslager and Kuroko, show the oceanic feature. It is concluded that the nickel content of igenous rock is a convenient tool for discrinimating the regional geological environment in which the magmatism has occurred.
