| 攀西层状基性超基性岩体岩浆类型及成因 |
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| 引用本文：.1987.Magmatic Types And Geneses Of The Layered Intrusions In Palnzhihua-Xichang Area[J].Mineral Deposits,6(2):1~15 |
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| 中文摘要:攀西层状岩体有两种类型。基性岩型和基性-超基性岩型。岩体韵律结构发育，具多旋回特征。其岩浆是直接来源于上地幔低度熔融的过渡型碱性橄榄玄武岩浆。岩浆演化具有周期性和铁钛早期富集的特点，与铁晚期富集的斯凯尔加德趋势明显不同。在上部岩浆房中，压力差别控制着岩浆演化途径，使岩浆结晶出不同类型的岩石组合。当压力超过5×108Pa时，形成红格型基性一超基性岩体，当压力小于5×108Pa时，形成攀枝花型基性岩体。 |
| 中文关键词:基性-超基性岩体 过渡型碱性橄榄玄武岩浆；韵律旋回铁钛早期富集；岩浆演化分离结晶作用 |
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| Magmatic Types And Geneses Of The Layered Intrusions In Palnzhihua-Xichang Area |
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| Abstract:The layered intrusions in Panxi area might be grouped into two types: basic rock masses represented by the Parizhihua rock body and basic-ultrabasic rock masses represented by the Hongge rock body. Their major difference is that the former has poorly developed ultramafic facies while the latter is characterized by most developed mafic facies and ultramafic facies. There exists apparent rhythmic stratification in the rock masses, which can be basically divided into four grades with superimposed relationship and multicycle characters present among different grades of rhythms. In the rhythm of Grade II, the basicity of rocks decreases from bottom to top, and ore beds are concentrated in the lower part. Both direct evidence and indirect evidence imply that the magma of layered intrusions :in this area should be a transitional kind of alkaline olivine basalt magma derived directly from partial melting of the upper mantle. In rhythmic cycles of various grades, the magmatic evolution is characterized obviously by periodicity and early enrichment of Fe and Ti, which is evidently different from the evolution of the Skaergaard magma in which Fe and Ti are enriched at late stage. The FCA diagram might be used to illustrate the specific evolutionary trend of magma iii this area. It is demonstrated in this diagram that the enrichment of Fe and Ti is consistent with the rising basicity. In the upper magmatic chamber, the evolutionary trend of magma is conditioned by the difference in pressure, and this enables magma to form different types of rock association. In the Fo-Di-An system, when the pressure exceeds 5×108Pa, forsterite is incompatible with anorthite, and the lithofacies sequence of Hongge type might form3when the pressure is lower than 5 X 108Pa, forsterite can coexist with anorthite, and the lithofacies sequence of Parzhihua type is likely to form if the magma is relatively rich in Mg and Fe components. |
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