K/Na Variation in Phlogopite and Amphibole of Upper Mantle Peridotites Due to Fractionation of the Metasomatizing Fluids
K/Na Variation in Phlogopite and Amphibole of Upper Mantle Peridotites Due to Fractionation of the Metasomatizing Fluids
复制标题
交代流体分馏导致上地幔橄榄岩金云母和角闪石的 K/Na 变化
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发表时间：
1986
期刊：
影响因子：
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通讯作者：
S. Arai
中科院分区：
文献类型：
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作者：
S. Arai
上地幔源区交代辉云母和角闪洞的K/Na比值在石榴石橄榄岩中较高，在尖晶石或斜长石橄榄岩中较低。结合观察到榴石橄榄岩中辉云母/角闪孔体积比高，尖晶石或斜长石橄榄岩中辉云母/角闪孔体积比低，认为交代部分的体积K/Na比在上地幔中向上减小。这种K/Na比值的垂直变化可能是由于交代流体中辉云母和角闪孔的分馏结晶所致。大块交代矿物的K/Na比值向上降低，至少是造成上地幔K/Na比值呈层状结构的部分原因。
K/Na ratios of metasomatic phlogopite and amphibole of the upper mantle origin are high in garnet peridotites and low in spinel or plagioclase peridotites. Combined with the observation that the phlogopite/ amphibole volume ratio is high in garnet peridotites and low in spinel or plagioclase peridotites, it is concluded that the bulk K/Na ratio of the metasomatized part decreases upwards in the upper mantle. This vertical variation of the K/Na ratio may be due to the fractional crystallization of phlogopite and amphibole from the metasomatizing fluids. The upward decrease of the K/Na ratio of the bulk metasomatic minerals is, at least partly, responsible for the layered structure of the upper mantle in terms of the K/Na ratio.