Abstract The ultra-alkaline rocks have exotic features that frustrated many attempts to group them in a single classification diagram. A consistent classification would be very useful to define a possible consanguinity, an argument that feed a living debate. This paper investigates the petrologic characteristics of the Cenozoic Italian ultra-alkaline rock-suite using -Rank Entropy Anentropy (RHA) and Principal Component Analysis (PCA)-. The RHA formula is the succession of component’s symbols arranged according to the diminishing of their elemental content in the analysis (whole rock composition). Other two parameters considered are an expression of the anentropy and entropy of the system. The PCA allows the definition of new latent variables based on geochemical compositions through linear combinations of the major oxides. Using both statistical methods was possible to create discrete groups of rock-types, associated by genetic relationship. The groups plotted in the Mg-Ca-Al ternary diagram depicts two main evolutionary arrays. We interpret the chemical variance in term of a general magmatic processes based on immiscibility and crystal fractionation. A comparison with similar association worldwide give a more general prospective to the magmato-tectonic assignment of these rocks, which is highly controversial in Italy.

中文翻译：

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意大利碱性火成岩地球化学系统学的一种新统计方法

摘要 超碱性岩石具有奇异的特征，这使许多将它们分组到单一分类图中的尝试受挫。一致的分类对于定义可能的血缘关系非常有用，这是一种引发生动辩论的论点。本文采用-Rank熵与熵权(RHA)和主成分分析(PCA)-研究了新生代意大利超碱性岩石组的岩石学特征。RHA 公式是根据分析中元素含量的减少（整个岩石成分）排列的成分符号的连续性。考虑的其他两个参数是系统的熵和熵的表达式。PCA 允许基于地球化学成分通过主要氧化物的线性组合定义新的潜在变量。使用这两种统计方法可以创建由遗传关系关联的离散岩石类型组。绘制在 Mg-Ca-Al 三元图中的组描绘了两个主要的演化阵列。我们根据基于不混溶性和晶体分馏的一般岩浆过程来解释化学变化。与世界范围内的类似协会进行比较，为这些岩石的岩浆构造分配提供了更广泛的前景，这在意大利极具争议。