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众所周知,在岩浆作用中控制岩浆演化的主要是岩浆熔体中常量元素的变化。总体上K_2O、Ma_2O、StO_2渐增高,MgO、CaO、FeO则渐降低,因此,出现K_2O/CaO、Na_2O/CaO、SiO_2/MgO比值相对增高。山于FeO减少不及MgO快,故FeO/HgO比值逐渐增高。对于Fe_2O_2/FeO比值则通常出现增高趋势。各主要深成岩中上述比值是不相同的。在相应的火山岩中类似的变化特征,仅因地表条件低铁氧化,故提高了Fe_2O_3/FeO比值。应用上述各比值时,应注意岩浆侵入产状及围岩成分、时代和演化、岩浆成因与其分异、分熔条件和构造环境条件变化等因素的影响。
It is well known that the magmatic evolution in magmatism is dominated by the variation of major elements in the magma melt. In general, K 2 O, Ma 2 O and StO 2 increased gradually while MgO, CaO and FeO decreased gradually. Therefore, the ratios of K 2 O / CaO, Na 2 O / CaO and SiO 2 / MgO increased relatively. Mountain FeO less than MgO faster, so the ratio of FeO / HgO gradually increased. For Fe 2 O 2 / FeO ratio is generally increased trend. The above major plutonic rocks in the ratio is not the same. Similar variations in the corresponding volcanic rocks increase the Fe_2O_3 / FeO ratio because of low iron oxidation at surface conditions. When applying these ratios, attention should be paid to the influence of magma intrusive occurrence, composition of surrounding rock, age and evolution, genesis and differentiation of magma, melting conditions and tectonic setting.