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云南鸡街碱性超基性岩杂岩体的主体岩石为岩浆结晶分异作用的产物,形成顺序为霞霓钠辉岩→霓霞岩→磷霞岩。在杂岩体的霓霞岩中发现了1粒具分带现象的橄榄石,从中心到边缘,SiO2、MgO和NiO逐渐降低,而FeO和MnO逐渐升高。MgO与SiO2和NiO之间呈正相关关系,与FeO和MnO之间呈负相关关系,中心的Fo值(最高为86 91)略高于霞霓钠辉岩中斑晶橄榄石(Fo值:85 66～86 02),而边缘的Fo值(最低为73 82)与霓霞岩中无分带现象橄榄石(Fo值:72 18～74 72)相近。各种证据表明,发现的具分带现象橄榄石可能不是霓霞岩熔体结晶分异作用的产物,而可能是霓霞岩熔体捕获的Fo值相对较高(高于霓霞岩橄榄石的Fo值)的橄榄石晶体内部MgO和FeO等成分扩散作用的结果。
The main rocks of the alkaline ultrabasic rocks in Jijiao, Yunnan are the products of the differentiation of magma crystals, and the order of formation is Xia Ni sodium hypochlorite → niixia → phoshiaoyu. One olivine with zonation was found in the kerogen of the complex rock. From the center to the edge, the contents of SiO2, MgO and NiO gradually decreased while the contents of FeO and MnO gradually increased. MgO has a positive correlation with SiO2 and NiO, but has a negative correlation with FeO and MnO. The Fo value in the center (up to 86 91) is slightly higher than that of the plagioclase peridotite 86 02), while the Fo value at the margin (the lowest is 73 82) is similar to the oldenite (Fo value: 72 18-74 72) in the absence of zonation in the Ni-Xia rocks. Various evidences indicate that the olivine with zonation found may not be the product of the crystalline differentiation of the ni-ni melt, but probably the Fo value captured by the ni-ni melt is relatively high (higher than that of the ni-olivine olivine Fo value) of the olivine crystal MgO and FeO and other ingredients as a result of the diffusion effect.