Batch fractionation model for the evolution of volcanic rocks in an island arc: an example from Central Japan
Batch fractionation model for the evolution of volcanic rocks in an island arc: an example from Central Japan
复制标题
岛弧火山岩演化的批量分馏模型：以日本中部为例
DOI：
10.1016/0012-821x(78)90095-x
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发表时间：
1978
影响因子：
5.3
通讯作者：
K. Ishizaka
中科院分区：
文献类型：
--
作者：
T. Yanagi;K. Ishizaka
对日本中部三座层状火山的51个岩石样本的分析表明，K和Rb的含量随火山的生长呈锯齿状变化。Rb（和K）呈锯齿状的峰谷变化模式先增大后逐渐收敛于恒定值。Rb/Sr比值也反映了这种变化趋势。峰值Rb/Sr趋同值（0.23-0.24）与最近大陆地壳平均值的估计一致。这些地球化学特征可以用间歇分馏模型很好地解释。在该模型中，位于地幔顶部的岩浆库周期性地提供一批母岩浆，而其中的岩浆不断结晶，堆积物在地幔的发散运动下不断被移走。该模型在岛弧壳幔结构的物理条件下工作，不仅解释了上述地球化学特征，而且对钙碱性岩系和大陆地壳的成因有重要意义。
Analyses of fifty-one rock samples from three stratovolcanoes in Central Japan revealed that K and Rb contents vary in a saw-toothed fashion with the growth of these volcanoes. Peaks and valleys of the saw-toothed variation pattern of Rb (and also K) increase at first and then gradually converge on constant values. This variation trend is also shown by the Rb/Sr ratio. The convergent Rb/Sr ratio (0.23–0.24) at the peaks coincides with recent estimates of the average value for continental crust. These geochemical features are well explained by the batch fractionation model. In this model, the magma reservoir lying at the top of the mantle is periodically supplied with a batch of parental magma, while the magma in it undergoes continuous crystallization and the cumulate is continuously removed by the divergent movement of the mantle. This model, working under physical conditions in the crust-mantle structure of an island arc, not only accounts for the above geochemical features, but also gives insight into the genesis of the calc-alkaline rock series and of the continental crust.