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Late Palaeozoic Ultramafic Lavas in Yunnan, SW China, and their Geodynamic Significance 总被引:5,自引:0,他引:5
We report petrological and geochemical data on ultramafic pillowlavas from Late Palaeozoic marine sequences in Yunnan, SW China.These lavas have >26 wt % MgO, euhedral to subhedral olivinephenocrysts and acicular or quench clinopyroxene crystals withor without microlitic plagioclase in a devitrified and alteredglassy matrix. These ultramafic lavas are compositionally komatiitic(>18 wt % MgO), but we term them high-Mg picrites becausethey lack spinifex-textured olivine. Although olivines in thesepicrites are cumulate crystals, causing the high MgO contentsof the bulk rocks, the high forsterite content of these olivines,Fo = 0·902 ± 0·011, suggests that the primitivemagmas parental to the picrites would have had 相似文献
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