Garnet/high-silica rhyolite trace element partition coefficients measured by ion microprobe
Garnet/high-silica rhyolite trace element partition coefficients measured by ion microprobe
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DOI：
10.1016/0016-7037(91)90129-s
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发表时间：
1991-06
影响因子：
5
通讯作者：
T. Sisson;C. Bacon
中科院分区：
文献类型：
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作者：
T. Sisson;C. Bacon
用离子探针测定了高硅流纹岩中辉石-液体微量元素的分配系数。报道了La、Ce、Nd、Sm、Dy、Er、Yb、Sc、Ti、V、Cr、Sr、Y和Zr的分配系数。这些环境分析避免了在传统的块状斑晶玻璃分配研究中遇到的富含微量元素的副矿物包裹体对辉石相的污染问题。已分析的辉石和玻璃是世界范围内典型的高硅流纹岩。所分析的样品是加利福尼亚州的Bishop Tuff(辉石，超辉石)，墨西哥的Sierra La Primavera(铁辉石)，以及怀俄明州哈克贝里山脉凝灰岩(铁辉石)的两个样品。稀土元素(REE)分配系数模式是凸起向上的，类似于较少硅质主体成分确定的模式。稀土元素锶、锆、铬的分配系数与单斜辉石的镁含量相关，表明晶体组成影响配分模式的精细结构。样品间配分模式的总体相似性表明，本研究确定的配分系数可普遍应用于高硅流纹岩的地球化学模拟。
Pyroxene-liquid trace element partition coefficients have been measuredin situby ion microprobe in high silica rhyolites. Partition coefficients are reported for La, Ce, Nd, Sm, Dy, Er, Yb, Sc, Ti, V, Cr, Sr, Y, and Zr. Thein situanalyses avoid the problem of contamination of the pyroxene phase by trace element-rich accessory mineral inclusions encountered in traditional bulk phenocryst-glass partitioning studies. Pyroxenes and glasses which have been analyzed are typical of high silica rhyolites worldwide. The samples analyzed are Bishop Tuff, California (augite, hypersthene); Sierra La Primavera, Mexico (ferrohedenbergite); and two samples of the Huckleberry Ridge Tuff, Wyoming (ferroaugite).Rare earth element (REE) partition coefficient patterns are convex-upward and resemble patterns determined in less silicic bulk compositions. Partition coefficients for the REEs Sr, Zr, and Cr show correlations with the Mg# of clinopyroxene, suggesting that crystal composition influences the fine structure of partitioning patterns. The overall similarity of partitioning patterns between samples indicates that the partition coefficients determined in this study can be generally applied in the geochemical modeling of high silica rhyolites.